Ca2+ handling alterations and vascular dysfunction in diabetes

Accepted Manuscript Title: Ca2+ handling alterations and vascular dysfunction in diabetes Author: Mar´ıa Fern´andez-Velasco Gema Ruiz-Hurtado Ana M. G´omez Ang´elica Rueda PII: DOI: Reference:

S0143-4160(14)00124-9 http://dx.doi.org/doi:10.1016/j.ceca.2014.08.007 YCECA 1593

To appear in:

Cell Calcium

Received date: Revised date: Accepted date:

17-6-2014 30-7-2014 7-8-2014

Please cite this article as: M. Fern´andez-Velasco, G. Ruiz-Hurtado, A.M. G´omez, A. Rueda, Ca2+ handling alterations and vascular dysfunction in diabetes, Cell Calcium (2014), http://dx.doi.org/10.1016/j.ceca.2014.08.007 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

HIGHLIGHTS:

1) We review alterations of vascular Ca2+ signaling proteins associated with the diabetic condition.

ip t

2) We emphasize alterations of Ca2+ signaling proteins in diabetic vascular smooth muscle.

cr

3) We report gender differences of functional STOC/spark coupling in the diabetic condition.

Ac ce p

te

d

M

an

us

 

1   

Page 1 of 38

Running head: Altered Ca2+ handling in diabetic vasculopathy

ip t

Ca2+ handling alterations and vascular dysfunction in diabetes

cr

María Fernández-Velascoa,1 Gema Ruiz-Hurtadob,c,1 Ana M. Gómezd and Angélica Ruedae,*. a

Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid, Spain. Unidad de Hipertensión, Instituto de Investigación imas12, Hospital 12 de Octubre, Madrid, Spain. c Instituto Pluridisciplinar, Facultad de Farmacia, Universidad Complutense de Madrid, Spain d Inserm, UMR S769; Faculté de Pharmacie, Université Paris Sud; Labex LERMIT; DHU TORINO; Châtenay-Malabry, France. e Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN. México City, México.

M

an

us

b

1

Ac ce p

te

d

*Corresponding author: Angélica Rueda Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, Avenida IPN 2508, Col. San Pedro Zacatenco, CP 07360 México City México Phone: (+52) 55-5747-3953 Fax: (+52) 55-5747-3391 e-mail: [email protected] both authors contributed equally to this work.

2   

Page 2 of 38

Abstract More than 65% of patients with diabetes mellitus die from cardiovascular disease or

ip t

stroke. Hyperglycemia, due to either reduced insulin secretion or reduced insulin sensitivity, is the hallmark feature of diabetes mellitus. Vascular dysfunction is a distinctive phenotype found

cr

in both types of diabetes and could be responsible for the high incidence of stroke, heart attack, and organ damage in diabetic patients. In addition to well-documented endothelial dysfunction,

us

Ca2+ handling alterations in vascular smooth muscle cells (VSMCs) play a key role in the

an

development and progression of vascular complications in diabetes. VSMCs provide not only structural integrity to the vessels but also control myogenic arterial tone and systemic blood

M

pressure through global and local Ca2+ signaling. The Ca2+ signalosome of VSMCs is integrated by an extensive number of Ca2+ handling proteins (i.e. channels, pumps, exchangers) and related

d

signal transduction components, whose function is modulated by endothelial effectors. This

te

review summarizes recent findings concerning alterations in endothelium and VSMC Ca2+

Ac ce p

signaling proteins that may contribute to the vascular dysfunction found in the diabetic condition.

Keywords: Vascular smooth muscle cells, endothelium, calcium signaling, calcium sparks, diabetes.

3   

Page 3 of 38

1.

Introduction

Hyperglycemia is the hallmark feature of diabetes mellitus (DM), due to either reduced

ip t

insulin secretion (T1DM) or reduced insulin sensitivity (T2DM). Vascular dysfunction is a distinctive phenotype found in both types of diabetes and likely contributes to the high incidence

cr

of stroke and heart attack, not to mention organ damage, such as retinopathy and nephropathy,

us

that is observed in diabetic patients. The latter complications are related to changes in the regulation of blood flow to the organ systems, mainly due to atherosclerosis and vascular

an

calcification, though additional molecular alterations are involved. The mechanisms by which vascular dysfunction appears in diabetes are complex, multifactorial, and include dramatic

M

alterations of the Ca2+ signaling pathways in both endothelial and vascular smooth muscle cell

d

(VSMC) layers.

te

Vascular endothelial dysfunction associated with the diabetic condition has been well characterized in the literature and summarized in excellent reviews [1, 2], including one article

Ac ce p

featured in this special issue of Cell Calcium. In addition, Ca2+ handling alterations in VSMCs contribute to blood vessel dysfunction associated with diabetes. VSMCs provide not only structural integrity to the vessels but also actively regulate arterial tone and local blood pressure via diverse Ca2+ signaling pathways [3]. Several groups of researchers have made available enough evidence to support the hypothesis that diabetes alters vascular function not only at the endothelial level but also at active smooth muscle layers [4-8]. Thus, this review focuses mainly on diabetes-related Ca2+ signaling alterations in endothelium and VSMCs that contribute to the development and progression of vascular dysfunction in diabetes.

4   

Page 4 of 38

2.

Ca2+ homeostasis in arterial cells

Arterial blood vessels have a well-established structure, comprising the tunica intima, tunica

ip t

media, and tunica adventitia. The tunica intima includes a monolayer of endothelial cells, which rests on a thin layer of connective tissue. Endothelial cells cover the internal surface of blood

cr

vessels, creating a barrier between circulating blood and VSMCs of the vessel wall. The tunica

us

media consists of a VSMC layer, which gives the vessel its mechanical and contractile strength, and therefore its tone. The spindle-shaped VSMCs are arranged in a circle surrounded by an

an

extracellular matrix consisting of elastin and collagen, which give the vessel its passive elasticity and distensibility. The tunica adventitia is made up of connective tissue, whose purpose is to

M

secure the blood vessel in place, and the nerve supply to the vessel [9]. VSMCs and endothelial cells are connected through gap junctions that allow the passage of intracellular second

d

messengers and local metabolites that modulate several functions, such as, flow-mediated

te

vasodilatation, mitogenic activity, platelet aggregation and neutrophil adhesion [10]. In resting

Ac ce p

conditions VSCMs are partially constricted and have intracellular Ca2+ concentrations ([Ca2+]i) around 100-300 nM [3]. However, different types of Ca2+ signals control excitation-contraction and relaxation mechanisms in these cells. Whereas the global rise in [Ca2+]i triggers contraction through activation of Ca2+/calmodulin-dependent myosin light chain kinase (MLCK), discretely localized Ca2+ release events via the intracellular Ca2+ channel/ryanodine receptor (RyR), or Ca2+ sparks, initiate vaso-relaxation [11]. In vivo, the augmentation of intraluminal pressure inside blood vessels causes Ca2+ influx in VSMCs, leading to contraction. Ca2+ influx in VSMCs is driven by several mechanisms: 1) activation of L-type voltage-dependent Ca2+ channels (VDCCs) after membrane depolarization, which triggers vascular contraction [12]; 2) the storeoperated Ca2+ entry (SOCE) mechanism [13], in which the reduction of SR Ca2+ load triggers the 5   

Page 5 of 38

movement of the SR Ca2+ sensor, stromal interaction molecule 1 (STIM1), towards the plasma membrane, where it activates Ca2+ influx via Orai1 Ca2+ channels [14]; and 3) activation of transient receptor potential ion channels (TRPs) associated with cell-surface receptors (ROCs),

ip t

or via STIM1-Orai1 protein interactions [15]. All of these are capable of inducing a momentary increase of Ca2+ in the vicinity of intracellular Ca2+ channels/ryanodine receptors (RyRs), so that

cr

more release would be expected if the classical Ca2+-induced Ca2+ release (CICR) process were

us

activated. However, Ca2+ entry via VDCCs is generally not further amplified by RyRs [16], it instead indirectly regulates RyR activity by reloading sarcoplasmic reticulum (SR) Ca2+ stores

an

through SR Ca2+ ATPase (SERCA pump) action [17].

M

In contrast to the well-established participation of RyR in cardiac and skeletal muscle contraction, the function of RyRs in smooth muscle physiology is not distinctively recognized.

d

While few studies have shown that vascular RyRs are involved in smooth muscle contraction

te

through the amplification of Ca2+ signals originated by VDCCs or inositol 1,4,5-trisphosphate

Ac ce p

receptor (IP3Rs) via CICR [18, 19], an increasing number of publications have demonstrated the participation of RyRs in vascular relaxation through the generation of local non-propagating Ca2+ signals [17]. Under physiological conditions, spontaneous and local increases of intracellular Ca2+ due to the opening of RyR clusters, visualized as Ca2+ sparks, activate nearby big conductance Ca2+ sensitive K+ channels (BK channels) that generate spontaneous transient outward currents (STOCs) [11, 17]. STOCs have a key role in the control of arterial tone by shifting cell membrane potential towards less positive values, which, in turn, limits Ca2+ influx through VDCCs, diminishes cytosolic [Ca2+]i, and opposes vasoconstriction. Therefore, Ca2+ sparks and STOCs are a functional coupled unit that regulates arterial tone. The most efficacious Ca2+ spark trigger mechanism in VSMCs appears to be luminal SR Ca2+ content, which is slowly 6   

Page 6 of 38

loaded via the SERCA pump [17]. In addition, several accessory proteins, such as FK 506 Binding Proteins (FKBPs), sorcin, and calmodulin, which bind to RyRs, forming a macromolecular complex, could be responsible for the early termination of Ca2+ release during a

ip t

Ca2+ spark. These proteins may also prevent additional Ca2+ release from adjacent release sites, restraining the regenerative behavior of CICR. Thus, Ca2+ has the ability to signal both

cr

contraction and relaxation; the fine tuning of these signals is a key feature of VSMCs.

us

Additionally, the activation of G-protein coupled receptors (GPCRs) induces contraction via the release of Ca2+ from the internal Ca2+ stores through IP3Rs. RyRs and IP3Rs are the two main

an

intracellular Ca2+ channels mediating SR Ca2+ release in VSMCs, but additional intracellular Ca2+-mobilizing channels have emerged in recent years, such as TRP-ML channels in lysosomes

M

[20]. During vascular relaxation, cytosolic Ca2+ is pumped back into stores located mainly at the SR by the activity of SERCA pump, and is extruded to the extracellular medium by the action of

te

d

the plasma membrane Ca2+ ATPase (PMCA) and the Na+/Ca2+ exchanger (NCX). Interestingly, an increasing number of reports have analyzed the contribution of altered Ca2+

Ac ce p

homeostasis in VSMCs to diabetes-related vascular disease. We will first analyze the contribution of endothelium to the overall vascular dysfunction observed in DM. 3. Endothelial dysfunction and vascular Ca2+ signaling in diabetes Endothelial cells regulate VSMCs and arterial tone by producing autocrine, paracrine, and endocrine signals that are modulated by Ca2+ [10, 21, 22]. Despite increasing evidence of a link between altered Ca2+ signaling and endothelial dysfunction in diabetes, the molecular mechanisms involved are not completely understood [10]. What we know for certain is that the endothelium of diabetic patients is affected by hyperglycemia, increased serum free fatty acids,

7   

Page 7 of 38

and insulin resistance through pathways that involve decreased nitric oxide (NO) production associated with augmented oxidative stress, apoptosis and endoplasmic reticulum stress [10, 22, 23]. Very recently, Sheikh et al. reported that T1DM results in significantly altered cardiac

ip t

endothelial [Ca2+]i due to reduced activity of SERCA pump and NCX [24], the former could participate in inducing endoplasmic reticulum stress [23]. It is worth noting that all these signals

us

cr

influence Ca2+ homeostasis in VSMCs [25-27].

3.1. Endothelial nitric oxide synthase and diabetes. Nitric oxide (NO) is a gas synthesized

an

by three mammalian isoforms of nitric oxide synthase: endothelial (eNOS), inducible (iNOS), and neuronal (nNOS) enzymes, with L-Arginine being the substrate for the enzymatic reaction.

M

eNOS is a Ca2+-dependent enzyme essential for regulating vascular tone and function. NO induces arterial vasodilation by increasing cGMP levels, which stimulates SERCA-mediated SR

d

Ca2+ uptake and induces VSMC hyperpolarization [28]. Endothelial dysfunction due to

te

impairment of NO-mediated relaxation, which has been described in both experimental models

Ac ce p

and in patients with DM [6, 29-31], compromises the regulation of vascular tone and promotes vascular inflammation and atherosclerosis [32, 33]. The molecular mechanisms by which high glucose levels impair NO synthesis in endothelial cells involve increasing reactive oxygen species (ROS) generation, augmented SOCE, and apoptosis [26, 27]. Since endothelial cells do not express VDCCs, Ca2+ influx relies on nonvoltage-dependent mechanisms, such as receptor-operated cation channels (ROCs), or those activated by store depletion, which are responsible for SOCE [34]. An increase in SOCE activates calpain, decreasing eNOS activation and availability [35]. Due to the fact that eNOS activity can be modulated by hyperglycemia, endothelial dysfunction in DM has been mainly

8   

Page 8 of 38

linked to changes in eNOS expression, but there are some discrepancies. On one side, eNOS downregulation has been found in human endothelial cells incubated with high glucose levels and in mammary arteries of diabetic patients [36, 37]. But other authors have found either an

ip t

increase or no change of eNOS expression in cultured endothelial cells exposed to high glucose

cr

levels and in a mouse model of T2DM [26, 38].

In VSMCs, NO promotes S-glutathiolation of the reactive cysteine 674 of the SERCA pump,

us

increasing its activity, and reducing Ca2+ influx and cell migration. Under hyperglycemic

an

conditions and impaired NO production, cysteine 674 is oxidized and VSMC migration is promoted [39]. iNOS, which is mainly expressed in VSMCs under conditions of inflammation

M

and septic shock, could also contribute to vascular damage in diabetes. In support of this idea, Di Prieto et al. have recently demonstrated that [Ca2+]i and iNOS protein levels are increased in

d

diabetic VSMCs after lipopolysaccharide challenge and that post-translational regulation of

te

iNOS activity under diabetic condition involves the CaMKIIδ2 signaling pathway [40].

Ac ce p

3.2 Inflammation, NF-κB, and NFAT. The reduced production of NO associated with diabetes promotes an increase of pro-inflammatory factors via the translocation of nuclear factor κ-B (NF-κB), which enhances the expression of leukocyte adhesion molecules, as well as the formation of chemokines and cytokines in endothelial cells [41]. All of these factors participate in the initial steps of atherosclerosis development [42]. Tumor necrosis factor (TNF-α) and NFκB are canonical mediators of vascular inflammation in atherosclerosis and play an important role in diabetic complications [42]. In fact, hyperglycemia alone is sufficient to promote the expression of pro-inflammatory mediators: for instance, interleukins 6 (IL-6) and 8 (IL-8), vascular cell adhesion molecule 1 (VCAM-1), and chemotactic protein 1 (MCP-1) all decrease

9   

Page 9 of 38

NO availability, leading to defective endothelium-dependent relaxation [43, 44]. VSMCs react to high glucose levels by increasing proliferation and migration rates. Cultured cells and intact aortas from mice exposed to hyperglycemia showed elevated levels of cytokines, such as TNF-α,

ip t

IL-1β and IL-6, adhesion molecules, and MCP-1[45, 46]. Another well-known pro-inflammatory

cr

enzyme is cyclooxygenase-2 (COX-2), which is upregulated in cultured human endothelial cells exposed to high glucose levels, and may promote an increase in arterial tone and blood pressure

us

in T2DM mice [47, 48].

an

Hyperglycemic effects are also mediated at the transcriptional level by nuclear factor of activated T cells (NFAT), which is well known to respond to high glucose levels [49]. For

M

instance, it has been observed that the exposure of cerebral artery VSMCs to high glucose induces an elevation in [Ca2+]i that activates calcineurin, which, in turn, dephosphorylates and

d

activates NFAT [49]. Also, the augmented Ca2+ influx reported in VSMCs of both Angiotensin II

te

(Ang II)-induced hypertension and T2DM models could induce calcineurin-mediated NFAT

Ac ce p

activation [50, 51] Upon activation, NFAT translocates into the nucleus, where it promotes gene expression of proteins related to cell proliferation and hypertrophy. In addition, nuclear accumulation of NFAT is associated with IP3R-mediated Ca2+ release and augmented Ca2+influx via VDCCs [52]. Therefore, targeting NFAT signaling may be a novel and attractive approach for the treatment of macrovascular complications, since its inhibition reduces atherosclerosis in experimental models of diabetes [53].

3.3 Reactive oxygen species in diabetes. An increase in reactive oxygen species (ROS) production is a hallmark of DM [32]. Indeed, hyperglycemia alone induces ROS overproduction [54, 55], which may oxidize cysteine 674 of SERCA pump, thereby impairing cytosolic Ca2+ 10   

Page 10 of 38

uptake [39]. Mitochondrial superoxide anion (O2-) production by NADPH oxidases is increased when vasculature is exposed to high glucose levels [55]. In coronary arterioles, O2- reacts rapidly with endothelium-derived NO, resulting in harmful peroxynitrite (ONOO-) formation and

ip t

decreased flow-induced dilation [56]. Hydrogen peroxide (H2O2) is a non-radical form of ROS highly present in VSMCs of T2DM mice. Elevated H2O2 levels contribute to increased

cr

production of constriction-promoting prostaglandins and enhanced tone of diabetic arterioles [57,

us

58].

an

3.4 Advanced glycation end products and diabetes. Advanced glycation end products (AGEs) also exacerbate vascular dysfunction in diabetes [55]. AGEs are the products resulting

M

from non-enzymatic protein and lipid glycation after being in contact with high glucose levels [59, 60]. The degree of hyperglycemia is a key factor in the AGE formation process; therefore,

d

during the progression of diabetes the generation of these compounds is significantly augmented

te

[61, 62]. Some of the adverse effects associated with AGE are mediated by receptors (RAGEs).

Ac ce p

RAGE activation stimulates the pro-inflammatory response. In endothelial and VSMCs, RAGE signaling results in the activation of mitogen-activated protein kinases (MAPK), ERK1/2, and Ras, mainly by the stimulation of nuclear factor-κB (NF-kB) [63-66]. Some researchers have analyzed the effect of AGEs on Ca2+ handling in endothelial and VSMCs. David et al. have demonstrated that incubation of porcine coronary VSMCs with glycated albumin (an AGE) prolonged the duration of sphingosine-1-phosphate (S1P)-induced [Ca2+]i increase, thereby activating calcineurin and NFAT [67].

4. Role of altered Ca2+ influx in diabetes

11   

Page 11 of 38

4.1 Voltage-dependent Ca2+ channels. L-type VDCCs play a key role in mediating Ca2+ entry into VSMCs; thus alterations in their expression and/or activity may strongly affect [Ca2+]i and consequently vascular function. Indeed, it has been shown that high glucose levels increase

ip t

basal [Ca2+]i in cultured A7r5 cell line [68], cultured rat tail artery VSMCs [69], aorta [70], and cerebral artery myocytes, in part due to a PKA-mediated increase in L-type Ca2+ currents [51]. In

cr

vascular cells, membrane depolarization achieved by high K+ in the bathing solution induces

us

activation of VDCC and contractile response. Blood vessels from diabetic animal models have shown an increase in the contractile response to extracellular K+, suggesting abnormalities in

an

VDCC function [71, 72]. Wang et al. were the first to study the biophysical properties of L-type VDCC current (ICa) in VSMCs from tail artery of STZ-induced diabetic rats (T1DM). The

M

authors observed that ICa density was significantly reduced in VSMCs, and that this reduction

d

progressed with time. The reduced ICa density could be attributed to a depression of the VDCC

te

PKA-dependent phosphorylation state, since ICa from DM cells was more sensitive to cAMP [71]. Similar data were collected in cultured VSMCs exposed to high levels of extracellular

Ac ce p

glucose for 24 h [71].

However, there are some disparities in how diabetic condition affects VDCC activity; these discrepancies could be due to the vascular bed of study or the diabetic condition (T1DM versus T2DM). In fact, more recent studies have pointed to an increase, instead of a decrease, in Ca2+ influx through VDCCs [72], according to the high vascular tone observed in diabetic patients [37, 73] and animal models [74-77]. Pinho et al. found an important vasoconstriction response in aortic rings from STZ-induced diabetic mice that was associated with higher density of ICa in isolated VSMCs through a pathway that involved phosphatidylinositol 3-kinase-δ (PI3Kδ; [72]). These authors have established that the upregulation of PI3Kδ signaling participates in the

12   

Page 12 of 38

vasoconstriction observed in diabetes; thus, the specific inhibition or the specific knock-down of PI3Kδ expression normalized ICa in VSMCs from diabetic mice to the level observed in control myocytes [72]. Likewise, Navedo et al. observed a significant increase in local Ca2+ influx

ip t

(named Ca2+sparklets) of diabetic db/db VSMCs from cerebral arteries, which was not the result of a broad activation of VDCCs but, rather, was due to a more local VDCC cluster activation

cr

[51]. The authors observed an elevation in the low but persistent activity of Ca2+ sparklet sites

us

during acute hyperglycemia or diabetes, and this effect was dependent on protein kinase A (PKA) activation (via the scaffolding protein A-kinase anchoring protein or AKAP) and

an

independent of protein kinase C (PKC) [51]. Unlikely, previous results obtained by the same group (although the study was done in mesenteric arteries of hypertensive animals), have shown

M

that in the case of Ang II-mediated hypertension the increase in [Ca2+]i was associated with augmented Ca2+ sparklet activity through activation of a PKC-dependent pathway [50]. In either

te

d

case, the persistent Ca2+ sparklet activity has an important physiological role in hypertrophy and proliferation of VSMC during diabetes, via the activation of NFAT [49, 50].

Ac ce p

4.2 Store-operated Ca2+ influx. It is well known that hyperglycemia is a key factor in the development of diabetic retinopathy, causing a significant increase in retinal vascular deterioration that leads to the appearance of blindness in many cases. Changes in retinal VSMCs [Ca2+]i may directly affect the arterial diameter [78]. In good agreement with this notion, Curtis et al. have demonstrated the contribution of Ca2+ handling alterations to the vascular deterioration found in diabetes. The authors observed that SOCE was significantly reduced in retinal microvessel preparations from STZ-induced diabetic rats through a mechanism that includes PKCβ upregulation [79]. However, in recent years more evidence supports the hypothesis that there is a switch from predominantly voltage- to predominantly non-voltage ion

13   

Page 13 of 38

channels (SOCs, ROCs and TRPs) in VSMCs during the development of diabetes-associated vascular diseases [80]. Indeed, Evans et al. observed that in VSMCs from Goto-Kakizaki (GK) rats, an experimental model of T2DM, AngII-induced Ca2+ influx was significantly enhanced

ip t

due to augmented TRPC activity (probably through the 1/4/5 isoforms of TRPC proteins; [81]). T2DM is often linked to obesity; thus some of the Ca2+ handling alterations in DM may be

cr

related to obesity. In support of this idea, it has been demonstrated that resistin, an adipocyte-

us

secreted cytokine that is significantly increased in several models of obesity [82], plays an important role in ET-1-mediated Ca2+ fluxes of VSMCs. Resistin is able to increase ET-1-

an

mediated Ca2+ signaling through the enhancement ERK-dependent SOCE mechanism. Moreover, STIM-1 has been demonstrated to directly participate in this effect, since silencing STIM-1 with

d

M

siRNA treatment abolished the resistin-dependent activation of SOCE in cultured VSMCs [83].

te

5. Role of altered GPCRs signaling in diabetes

Ac ce p

GPCRs and their physiological ligands are important players in the vascular dysfunction observed in diabetes. Indeed, researchers have observed a significant increase in the expression levels of the heterotrimeric Gαq/11 proteins and phospholipase C-β (60% and 30%, respectively) in aortic VSMCs exposed to high glucose levels or isolated from STZ-induced diabetic rats. This effect was attributed to the activation of AngII type 1 and ET-1 receptors (AT1Rs and ETA/ETBRs, respectively) [84]. AT1R was the first GPCR discovered to be involved in the vascular mechanosensitive response [85, 86]. In VSMCs, AT1Rs are coupled to several intracellular transduction pathways: for instance, the activation of Ca2+ influx and Ca2 release is coupled to PLC, PKC, and mitogen-activated protein (MAP) kinase pathways, among others [87]. There are a considerable number of studies that have demonstrated enhanced AngII14   

Page 14 of 38

induced vessel contractility in animal models of T1DM and T2DM [81, 88, 89]. By contrast, Sharma et al. reported a significant decrease in the AngII-induced cytosolic Ca2+ mobilization in aortic VSMCs from STZ-induced rats [90]. This observation correlated well with a diminished

ip t

AngII-induced aortic ring contraction in diabetic rats; both effects involved production of

cr

transforming growth factor beta (TGF-β).

us

On the other hand, an interesting study carried out by Bagi et al. demonstrated that the sustained Ang-II-induced vasoconstriction observed in diabetic arteries is due to an impairment

an

of the normal desensitization and consequent internalization of AT1Rs, usually observed under repeated AngII administration in control conditions (a process named tachyphylaxis) [91]. The

M

authors also observed that high-glucose conditions help to maintain a sustained surface presence

d

of AT1Rs after repeated AngII stimulation. Moreover, the Rho-kinase-dependent pathway has

te

been implicated in this effect, since the surface level of AT1Rs are reduced by Rho-kinase inhibition in VSMCs exposed to high glucose concentration [91]. In addition, the Rho-kinase-

Ac ce p

dependent pathway is also involved in vasoconstriction and proliferation effects of the GPCR urotensin II (UII) receptor in diabetic VSMCs [92]. Interestingly, it was recently shown that activation of SOCE though STIM1, Orai1, and TRPC1 is required for vascular proliferative actions of UII in primary cultures of aortic VSMCs [93]. Another bioactive sphingolipid metabolite that exerts its effects through five different types of GPCRs is sphingosine-1-phosphate (S1P acting through S1P receptors 1-5; [94]). It is known that sphingolipid metabolism is altered in vascular diseases associated with diabetes and obesity. However, few studies have examined the role of S1P in this field. It is known that plasma levels of S1P are increased in animal models of T1DM [95]. In fact, deficient type-2-S1PR mice

15   

Page 15 of 38

displayed greater survival rates compared with wild type mice when treated with STZ to induce diabetes. This finding was attributed to an attenuation of STZ-induced apoptosis in the S1PR2-/mice [94, 96]. Interestingly, S1PR2 modulates intracellular Ca2+ signaling in VSMCs and

ip t

contributes to S1P-induced vasoconstriction [97, 98].

GPCRs are known to act synergistically with TRPCs, named GPCR-dependent TRPC

cr

activation in the case of DAG-sensitive TRPC3/6/7 channels [86, 99]. In this regard, SP1 triggers

us

STIM1 puncta formation and activates SOCE through an IP3R-dependent pathway, which is increased in proliferative VSMCs. This synergic activation could be relevant for the vascular

an

dysfunction associated with diabetes [100]. These results are important because it is known that SOCE activation is involved in the phosphorylation of cAMP response element-binding (CREB)

d

M

protein and in the upregulation of proliferative genes [100, 101].

te

6. Modifications in intracellular Ca2+ cycling and extrusion mechanisms in diabetes. Thus, on one hand, the enhanced arterial tone and diminished vaso-relaxation responses in

Ac ce p

arteries of DM patients and animal models could be explained, in part, by an augmented Ca2+ influx via VDCCs or other non-dependent voltage channels, which induces a rise in the basal [Ca2+]i, with the concomitant tonic activation of the contraction machinery. But on the other hand, the functional impairment of the mechanisms that counterbalance this Ca2+ influx, for instance, Ca2+ spark/STOC coupling and Ca2+ extrusion mechanisms (pumps and exchangers) could also participate in the DM vascular dysfunction. 6.1. Ryanodine Receptors. The RyR is a tetrameric protein located at the SR membrane of VSMCs. The three mammalian isoforms (RyR1-3) are expressed in VSMCs with relative levels of each determined by the type of vascular bed [102]. Interestingly, it has been shown that RyR

16   

Page 16 of 38

subtypes distribute differentially among subcellular compartments [103]. In this regard, it was shown that the subcellular distribution of RyR was modified when A7r5 cells were exposed to high glucose levels. RyR moved from SR locations toward perinuclear regions, leading to

ip t

inappropriate BK channel activation with a concomitant decline of vaso-relaxation [68]. Pioneering work using tail artery VSMCs of STZ-induced diabetic rats convincingly

cr

demonstrated that RyRs participate in diabetes-enhanced Ca2+ oscillations induced by

us

norepinephrine treatment [104]. Unsurprisingly, reduced expression of RyR has been found in several experimental models of DM, regardless of the type of diabetes [105, 106]. Along with

an

lower RyR expression, we demonstrated a concomitant diminution of Ca2+ spark parameters (for instance, mean amplitude, duration, size and rate-of-rise) in freshly isolated cerebral artery

M

VSMCs of male db/db mice, though Ca2+ spark frequency remained similar [106]. However, STOCS frequency was greatly depressed, perhaps due to a depression on BK channel expression

te

d

and/or the decrease in the amount of Ca2+ released in each Ca2+ spark [106]. By contrast, the expression of RyRs has been shown to be higher than controls in the aortas of STZ-treated rats

Ac ce p

and DR-BB diabetic animals; the same finding was reproduced in cultured A7r5 cells grown in high glucose concentrations [68]. Accordingly, Ca2+ spark frequency has been found to be either unaltered [107], or increased [108] in DM1 experimental models. An important consideration in experimental models is the gender of the animal of study, which in most cases are males. In fact, although diabetes has similar effects in men and women, it has been shown that microvascular alterations occur preferentially in men [109]. With this in mind, we repeated our experiments (cited above, [106]) in female db/db mice. In contrast to the results found in males, the amplitude of spontaneous Ca2+ sparks recorded in VSMCs from female db/db mice remained unchanged, while the frequency showed only a slight, but non17   

Page 17 of 38

significant reduction in comparison with female control cells (Fig. 1A and B). Non-diabetic controls (+/+) showed a noticeable difference in Ca2+ spark amplitude between males and females. VSMCs from female mice presented weaker Ca2+ sparks amplitudes than that of males;

ip t

while mean spark frequency was higher in female cells (Fig. 1A and B). These data clearly show gender differences in the regulation of vascular RyR activity that are independent of the diabetic

cr

condition.

us

6.2. BK channels. As mentioned earlier, Ca2+ sparks activate BK channels, which play a

an

critical role in controlling vascular myogenic tone [11, 17]. Vascular BK channels are composed of four pore-forming α-subunits and four accessory β-subunits, β1 being the predominant

M

isoform expressed in VSMCs. The α-subunit contains the pore forming region, while the β1subunit enhances the sensitivity of BK channels to Ca2+-dependent activation [110].

d

Downregulation or genetic disruption of β1 subunit has been implicated in the pathogenesis of

te

arterial hypertension [111]. In experimental models of T1DM and T2DM, the activity of BK

Ac ce p

channels has been found to be depressed, mainly due to a reduction in β1 subunit expression leading to vasoconstriction [106-108, 112, 113]. In cerebral artery VSMCs from diabetic male mice, we found a significant reduction of STOC frequency across all voltages tested [106]. Particularly, STOC frequency recorded at -40 mV, a voltage near the resting membrane potential, was significantly reduced in diabetic males but not in female myocytes (Fig. 1C). Intriguingly, STOC amplitude was not modified by the diabetic condition, though STOC amplitude was found to be higher in myocytes from females (Fig. 1D), arguing in favor of estrogen regulation of BK Ca2+ sensitivity. When we estimated STOC/Ca2+ spark frequency ratio (Fig. 1E) by dividing the frequency of STOCs in each cell at near resting membrane potential by the mean frequency of Ca2+ sparks in quiescent cells, we found a significant reduction only in 18   

Page 18 of 38

diabetic male cells. The same approach was used to estimate STOC/Ca2+ spark amplitude ratio, which was significantly enhanced in female VSMCs regardless of the diabetic condition (Fig. 1F), pointing to enhanced Ca+ sensitivity of BK channel in female cells, which were able to fire

ip t

bigger STOCs with sparks of reduced amplitude.

Many factors, including oxidative stress, could be involved in the downregulation of BK

cr

channels observed under diabetic conditions. For instance, high glucose levels activate

us

calcineurin and NFAT in VSMCs during hypertension [49], but this mechanism might also downregulate BK channels [50]. High glucose levels may also induce a decrease in the activity

an

of voltage-gated K+ channels (Kv) expressed in VSMCs via oxidative stress, promoting arterial vasoconstriction [114]. Also, ONOO- and ROS may inhibit vascular BK channel activity, though

M

O2- has no effect [115, 116]. H2O2 may either inhibit or activate BK channels through direct

d

effects or through cGMP- and cAMP-dependent signaling pathways [117-119]. More recently,

te

Lu et al. demonstrated that ROS overproduction detected in aorta of T1DM mice blocked Aktmediated FOXO-3a phosphorylation, accelerating BK-β1 degradation, and worsening coronary

Ac ce p

vasodilation [120]. But it is important to note that downregulation of BK channels could be considered a late maladaptive response: in metabolic syndrome, a condition considered to be prediabetic, BK channel subunit expression is augmented even in the presence of depressed BK channel function [121].

6.3. Inositol 1,4,5-trisphosphate receptors. A significant downregulation of the type I of IP3Rs has been observed in diabetic aortic and renal tissues from STZ-treated rats, mediated by TGF-β production [90, 122]. The same experimental model was used to demonstrate a significant decrease in both IP3- and RyR-sensitive Ca2+ release, accompanied by a reduction in

19   

Page 19 of 38

the expression levels of both channels [105]. Similar results have been found in aortic VSMCs from STZ-treated rats and autoimmune T1DM-resistant bio-breeding (DR-BB) animals [68]. A significant decrease in IP3R expression levels was also found in cultured VSMCs that were

ip t

chronically exposed to hyperglycemia [68]. On the other hand, IP3R activity is modulated by protein-protein interactions; for instance, with the anti-apoptotic proteins Bcl-2 and Bcl-xL which

cr

modulate IP3R-dependent intracellular Ca2+ signaling in diabetes [123-125]. In the recent

us

contribution of Velmurugan et al., it was demonstrated that IP3-induced [Ca2+]i transients were significantly larger in VSMCs from diabetic db/db mice (T2DM); this response was not

an

explained by augmentation of either the SR Ca2+ store or the expression levels of IP3Rs isoforms [125]. However, these effects might be attributable to enhanced IP3R excitability via Bcl-xL-IP3R

M

protein interactions [126]. These results potentially have important physiological consequences for cellular processes such as apoptosis and proliferation in diabetes. It is worth mentioning that

te

d

animals that survive partial IP3R1 depletion (IP3R1+/- mice) show augmented susceptibility to

Ac ce p

glucose intolerance, insulin resistance, and diet-induced diabetes [127, 128].

6.4 SERCA pump and additional Ca2+ removal mechanisms. Elevated basal [Ca2+]i has been reported in diabetic VSMC of rodent models, suggesting an impairment of cytosolic Ca2+ extrusion mechanisms; however, some other publications report no change, or even a significant reduction in resting [Ca2+]i levels [68, 106]. The nature of these disparities has not been determined, but might be due to differences associated with the vascular beds, recording conditions, and cell isolation procedures. In fact, it was previously established that decreasing SR Ca2+ load could account for the diminished Ca2+ spark properties in vascular myocytes. With regard to diabetes, cytokines (i.e. interleukin-1 and c-interferon), which are increased in db/db

20   

Page 20 of 38

mice, reportedly depress SERCA function [129]. Accordingly, the amounts of SERCA pump isoforms 2 and 3 were significantly reduced in aorta and femoral arteries of two different models of T1DM. Both isoforms also showed altered distribution towards nuclear/perinuclear regions in

ip t

diabetes [68]. Accordingly, the activities of SERCA and NCX were found to be blunted in coronary VSMCs of diabetic swine [130]. Because NCX protects cells against Ca2+ overload and

cr

participates in improving endothelium-dependent vascular relaxation, it follows that alterations

us

in its function are associated with DM vasculopathy.

an

7. Vascular Ca2+ handling proteins as therapeutic targets in diabetes Our current understanding of the most relevant findings in the alteration of Ca2+ signaling

M

proteins related to the diabetic condition is summarized in Table 1 and Fig 2 of this review. The

d

vast majority of therapeutic strategies to ameliorate the deteriorated vascular function in diabetes

te

are mainly administered to 1) improve endothelium-dependent NO production by increasing NO bioactivity or inducing eNOS expression [2]; 2) reduce oxidative stress damage by using ROS

Ac ce p

scavengers and antioxidants [26, 39]; 3) reduce inflammatory responses by inhibiting COX2 activity; and 4) reverse or prevent DM-induced vascular dysfunction by subjecting DM patients or experimental DM animal models to a program of exercise training [130, 131]. Though these strategies indeed improve the function of VSMCs, few of those have been directly designed to recover dysfunctional VSMCs. Clinical studies have demonstrated that antagonists of AT1Rs are effective in the prevention of vascular dysfunction associated with diabetes [132], probably by reducing Ca2+ influx in VSMCs. In a study of mesenteric arteries isolated from GK rats, treatment with losartan, an anti-hypertensive drug, was found to increase BK channel activity [133]; however, the molecular mechanism has not been completely elucidated. Further, 5-week

21   

Page 21 of 38

treatment of diabetic mice with rotenone, a mitochondrial electron transport chain uncoupler, partially recovers BK currents in cerebral artery VSMCs by reducing the production of ROS [134]. Finally, the recently described S1P/SOCE pathway could be an important therapeutic

ip t

target in diabetic vascular diseases, as specific S1PR2 blockage attenuated apoptosis of pancreatic beta-cells, decreasing the risk of vascular diabetic complications in animal models

cr

[96]. Future treatments should consider targeting key Ca2+ handling proteins of VSMCs, such as

us

RyRs, IP3R, BK channels, and SERCA pump, to improve their function and ameliorate the

Ac ce p

te

d

M

an

deterioration of blood vessels in diabetes.

22   

Page 22 of 38

Conflict of interest: None. Acknowledgements. Authors would like to thank Dr. Michelle Capes for excellent comments

ip t

and helpful reading of the manuscript. Funding: SEP-CONACYT-ANUIES-ECOS Nord (M13S01) to AR and AMG; ANR-13-BSV1-0023-01 to AMG; Fundación Mutua Madrileña and

cr

Fundación Eugenio Rodriguez Pascual to GRH. In addition, GRH was funded by the Ministerio

Ac ce p

te

d

M

an

us

de Economía y Competitividad from Spain (Juan de la Cierva Postdoctoral program).

23   

Page 23 of 38

REFERENCES

Ac ce p

te

d

M

an

us

cr

ip t

[1]  C.E.  Tabit,  W.B.  Chung,  N.M.  Hamburg,  J.A.  Vita,  Endothelial  dysfunction  in  diabetes  mellitus:  molecular mechanisms and clinical implications, Rev Endocr Metab Disord, 11 (2010) 61‐74.  [2] E.C. Eringa, E.H. Serne, R.I. Meijer, C.G. Schalkwijk, A.J. Houben, C.D. Stehouwer, Y.M. Smulders, V.W.  van  Hinsbergh,  Endothelial  dysfunction  in  (pre)diabetes:  characteristics,  causative  mechanisms  and  pathogenic role in type 2 diabetes, Rev Endocr Metab Disord, 14 (2013) 39‐48.  [3] A. Marchand, A. Abi‐Gerges, Y. Saliba, E. Merlet, A.M. Lompré, Calcium signaling in vascular smooth  muscle cells: from physiology to pathology, Adv Exp Med Biol, 740 (2012) 795‐810.  [4]  G.E.  McVeigh,  G.M.  Brennan,  G.D.  Johnston,  B.J.  McDermott,  L.T.  McGrath,  W.R.  Henry,  J.W.  Andrews,  J.R.  Hayes,  Impaired  endothelium‐dependent  and  independent  vasodilation  in  patients  with  type 2 (non‐insulin‐dependent) diabetes mellitus, Diabetologia, 35 (1992) 771‐776.  [5] L.P. Weber, W.L. Chow, W. Abebe, K.M. MacLeod, Enhanced contractile responses of arteries from  streptozotocin diabetic rats to sodium fluoride, Br J Pharmacol, 118 (1996) 115‐122.  [6] S.B. Williams, J.A. Cusco, M.A. Roddy, M.T. Johnstone, M.A. Creager, Impaired nitric oxide‐mediated  vasodilation in patients with non‐insulin‐dependent diabetes mellitus, J Am Coll Cardiol, 27 (1996) 567‐ 574.  [7] V. Piercy, S. Taylor, A comparison of spasmogenic and relaxant responses in aortae from C57/BL/KsJ  diabetic mice with those from their non‐diabetic litter mates., Pharmacology, 56 (1998) 267‐275.  [8] Z. Bagi, A. Koller, G. Kaley, Superoxide‐NO interaction decreases flow‐ and agonist‐induced dilations  of  coronary  arterioles in Type 2 diabetes mellitus., Am J Physiol Heart Circ Physiol, 285 (2003) H1404‐ 1410.  [9]  V.  Sharma,  J.  McNeill,  The  etiology  of  hypertension  in  the  metabolic  syndrome  part  three:  the  regulation and dysregulation of blood pressure, Curr Vasc Pharmacol, 4 (2006) 321‐348.  [10]  C.R.  Triggle,  S.M.  Samuel,  S.  Ravishankar,  I.  Marei,  G.  Arunachalam,  H.  Ding,  The  endothelium:  influencing vascular smooth muscle in many ways, Can J Physiol Pharmacol, 90 (2012) 713‐738.  [11]  M.  Nelson,  H.  Cheng,  M.  Rubart,  L.  Santana,  A.  Bonev,  H.  Knot,  W.  Lederer,  Relaxation of arterial  smooth muscle by calcium sparks, Science, 270 (1995) 633‐637.  [12] W.F. Jackson, Ion channels and vascular tone, Hypertension, 35 (2000) 173‐178.  [13] A.B. Parekh, J.W. Putney, Store‐operated calcium channels, Physiol Rev, 85 (2005) 757‐810.  [14]  J.  Soboloff,  M.A.  Spassova,  X.D.  Tang,  T.  Hewavitharana,  W.  Xu,  D.L.  Gill,  Orai1  and  STIM  reconstitute store‐operated calcium channel function, J Biol Chem, 281 (2006) 20661‐20665.  [15] J.P. Yuan, K.P. Lee, J.H. Hong, S. Muallem, The closing and opening of TRPC channels by Homer1 and  STIM1, Acta Physiol (Oxf), 204 (2012) 238‐247.  [16]  M.  Collier,  G.  Ji,  Y.  Wang,  M.  Kotlikoff,  Calcium‐induced  calcium  release  in  smooth  muscle:  loose  coupling between the action potential and calcium release, J Gen Physiol, 115 (2000) 653‐662.  [17]  K.  Essin,  M.  Gollasch,  Role  of  ryanodine  receptor  subtypes  in  initiation  and  formation  of  calcium  sparks  in  arterial  smooth  muscle:  comparison  with  striated  muscle,  J  Biomed  Biotechnol,  2009  (2009)  135249.  [18]  F.X.  Boittin,  N.  Macrez,  G.  Halet,  J.  Mironneau,  Norepinephrine‐induced  Ca(2+)  waves  depend  on  InsP(3) and ryanodine receptor activation in vascular myocytes, Am J Physiol, 277 (1999) C139‐151.  [19] F. Coussin, N. Macrez, J.L. Morel, J. Mironneau, Requirement of ryanodine receptor subtypes 1 and  2 for Ca(2+)‐induced Ca(2+) release in vascular myocytes, J Biol Chem, 275 (2000) 9596‐9603.  [20]  P.L.  Li,  Y.  Zhang,  J.M.  Abais,  J.K.  Ritter,  F.  Zhang,  Cyclic  ADP‐Ribose  and  NAADP  in  Vascular  Regulation and Diseases, Messenger (Los Angel), 2 (2013) 63‐85.  [21]  R.F.  Furchgott,  J.V.  Zawadzki,  The  obligatory  role  of  endothelial  cells  in  the  relaxation  of  arterial  smooth muscle by acetylcholine, Nature, 288 (1980) 373‐376.  24   

Page 24 of 38

Ac ce p

te

d

M

an

us

cr

ip t

[22]  H.  Ding,  C.R.  Triggle,  Endothelial  dysfunction  in  diabetes:  multiple  targets  for  treatment,  Pflugers  Arch, 459 (2010) 977‐994.  [23]  B. Basha, S.M. Samuel, C.R. Triggle, H. Ding, Endothelial dysfunction in diabetes mellitus: possible  involvement of endoplasmic reticulum stress?, Exp Diabetes Res, 2012 (2012) 481840.  [24]  A.Q.  Sheikh,  J.R.  Hurley,  W.  Huang,  T.  Taghian,  A.  Kogan,  H.  Cho,  Y.  Wang,  D.A.  Narmoneva,  Diabetes alters intracellular calcium transients in cardiac endothelial cells, PLoS One, 7 (2012) e36840.  [25] D. Tousoulis, A.M. Kampoli, N. Papageorgiou, S. Papaoikonomou, C. Antoniades, C. Stefanadis, The  impact  of  diabetes  mellitus  on  coronary artery disease: new therapeutic approaches, Curr Pharm Des,  15 (2009) 2037‐2048.  [26]  J.Z.  Sheng,  D.  Wang,  A.P.  Braun,  DAF‐FM  (4‐amino‐5‐methylamino‐2',7'‐difluorofluorescein)  diacetate detects impairment of agonist‐stimulated nitric oxide synthesis by elevated glucose in human  vascular endothelial cells: reversal by vitamin C and L‐sepiapterin, J Pharmacol Exp Ther, 315 (2005) 931‐ 940.  [27] S. Tamareille, O. Mignen, T. Capiod, C. Rucker‐Martin, D. Feuvray, High glucose‐induced apoptosis  through  store‐operated  calcium  entry  and  calcineurin  in  human  umbilical  vein  endothelial  cells,  Cell  Calcium, 39 (2006) 47‐55.  [28] M. Ferrer, J. Marín, A. Encabo, M.J. Alonso, G. Balfagón, Role of K+ channels and sodium pump in  the  vasodilation  induced  by  acetylcholine,  nitric  oxide,  and  cyclic  GMP  in  the  rabbit  aorta,  Gen  Pharmacol, 33 (1999) 35‐41.  [29] M.T. Johnstone, S.J. Creager, K.M. Scales, J.A. Cusco, B.K. Lee, M.A. Creager, Impaired endothelium‐ dependent  vasodilation  in  patients  with  insulin‐dependent  diabetes  mellitus,  Circulation,  88  (1993)  2510‐2516.  [30]  S.  Makimattila,  A.  Virkamaki,  P.H.  Groop,  J.  Cockcroft,  T.  Utriainen,  J.  Fagerudd,  H.  Yki‐Jarvinen,  Chronic  hyperglycemia  impairs  endothelial  function  and  insulin  sensitivity  via  different  mechanisms  in  insulin‐dependent diabetes mellitus, Circulation, 94 (1996) 1276‐1282.  [31] W.A. Hsueh, M.J. Quinones, Role of endothelial dysfunction in insulin resistance, Am J Cardiol, 92  (2003) 10J‐17J.  [32]  M.A.  Creager,  T.F.  Luscher,  F.  Cosentino,  J.A.  Beckman,  Diabetes  and  vascular  disease:  pathophysiology, clinical consequences, and medical therapy: Part I, Circulation, 108 (2003) 1527‐1532.  [33]  C.  Szabo,  Role  of  nitrosative  stress  in  the  pathogenesis  of  diabetic  vascular  dysfunction,  British  journal of pharmacology, 156 (2009) 713‐727.  [34] B. Nilius, G. Droogmans, Ion channels and their functional role in vascular endothelium, Physiol Rev,  81 (2001) 1415‐1459.  [35]  T.J.  Stalker,  Y.  Gong,  R.  Scalia,  The  calcium‐dependent  protease  calpain  causes  endothelial  dysfunction in type 2 diabetes, Diabetes, 54 (2005) 1132‐1140.  [36] Y. Ding, N.D. Vaziri, R. Coulson, V.S. Kamanna, D.D. Roh, Effects of simulated hyperglycemia, insulin,  and glucagon on endothelial nitric oxide synthase expression, Am J Physiol Endocrinol Metab, 279 (2000)  E11‐17.  [37] E.B. Okon, A.W. Chung, P. Rauniyar, E. Padilla, T. Tejerina, B.M. McManus, H. Luo, C. van Breemen,  Compromised arterial function in human type 2 diabetic patients, Diabetes, 54 (2005) 2415‐2423.  [38]  H.  Ding,  M.  Aljofan,  C.R.  Triggle,  Oxidative  stress  and  increased  eNOS  and  NADPH  oxidase  expression in mouse microvessel endothelial cells, J Cell Physiol, 212 (2007) 682‐689.  [39] X. Tong, A. Evangelista, R.A. Cohen, Targeting the redox regulation of SERCA in vascular physiology  and disease, Curr Opin Pharmacol, 10 (2010) 133‐138.  [40]  N.  Di  Pietro,  P.  Di  Tomo,  S.  Di  Silvestre,  A.  Giardinelli,  C.  Pipino,  C.  Morabito,  G.  Formoso,  M.A.  Mariggiò,  A.  Pandolfi,  Increased  iNOS  activity  in  vascular  smooth  muscle  cells  from  diabetic  rats:  potential  role  of  Ca(2+)/calmodulin‐dependent  protein  kinase  II  delta  2  (CaMKIIδ(2)),  Atherosclerosis,  226 (2013) 88‐94.  25   

Page 25 of 38

Ac ce p

te

d

M

an

us

cr

ip t

[41]  A.M.  Zeiher,  B.  Fisslthaler,  B.  Schray‐Utz,  R.  Busse,  Nitric  oxide  modulates  the  expression  of  monocyte chemoattractant protein 1 in cultured human endothelial cells, Circ Res, 76 (1995) 980‐986.  [42]  A.K.  Mohamed,  A.  Bierhaus,  S.  Schiekofer,  H.  Tritschler,  R.  Ziegler,  P.P.  Nawroth,  The  role  of  oxidative stress and NF‐kappaB activation in late diabetic complications, Biofactors, 10 (1999) 157‐167.  [43]  M.M.  Hartge,  T.  Unger,  U.  Kintscher,  The  endothelium  and  vascular  inflammation  in  diabetes,  Diabetes  &  vascular  disease  research  :  official  journal  of  the  International  Society  of  Diabetes  and  Vascular Disease, 4 (2007) 84‐88.  [44]  M.  Urakaze,  R.  Temaru,  A.  Satou,  K.  Yamazaki,  T.  Hamazaki,  M.  Kobayashi,  The  IL‐8  production  in  endothelial cells is stimulated by high glucose, Horm Metab Res, 28 (1996) 400‐401.  [45]  E.  Dragomir,  I.  Manduteanu,  M.  Calin,  A.M.  Gan,  D.  Stan,  R.R.  Koenen,  C.  Weber,  M.  Simionescu,  High  glucose  conditions  induce  upregulation  of  fractalkine  and  monocyte  chemotactic  protein‐1  in  human smooth muscle cells, Thrombosis and haemostasis, 100 (2008) 1155‐1165.  [46]  N.  Labinskyy,  P.  Mukhopadhyay,  J.  Toth,  G.  Szalai,  M.  Veres,  G.  Losonczy,  J.T.  Pinto,  P.  Pacher,  P.  Ballabh, A. Podlutsky, S.N. Austad, A. Csiszar, Z. Ungvari, Longevity is associated with increased vascular  resistance  to  high  glucose‐induced  oxidative  stress  and  inflammatory  gene  expression  in  Peromyscus  leucopus, Am J Physiol Heart Circ Physiol, 296 (2009) H946‐956.  [47] F. Cosentino, M. Eto, P. De Paolis, B. van der Loo, M. Bachschmid, V. Ullrich, A. Kouroedov, C. Delli  Gatti, H. Joch, M. Volpe, T.F. Luscher, High glucose causes upregulation of cyclooxygenase‐2 and alters  prostanoid  profile  in  human  endothelial  cells:  role  of  protein  kinase  C  and  reactive  oxygen  species,  Circulation, 107 (2003) 1017‐1023.  [48] Z. Bagi, N. Erdei, A. Toth, W. Li, T.H. Hintze, A. Koller, G. Kaley, Type 2 diabetic mice have increased  arteriolar  tone  and  blood  pressure:  enhanced  release  of  COX‐2‐derived  constrictor  prostaglandins,  Arterioscler Thromb Vasc Biol, 25 (2005) 1610‐1616.  [49] J. Nilsson, L.M. Nilsson, Y.W. Chen, J.D. Molkentin, D. Erlinge, M.F. Gomez, High glucose activates  nuclear  factor  of  activated  T cells in native vascular smooth muscle, Arterioscler Thromb Vasc Biol, 26  (2006) 794‐800.  [50]  M.  Nieves‐Cintrón,  G.C.  Amberg,  M.F.  Navedo,  J.D.  Molkentin,  L.F.  Santana,  The  control  of  Ca2+  influx and NFATc3 signaling in arterial smooth muscle during hypertension, Proc Natl Acad Sci U S A, 105  (2008) 15623‐15628.  [51] M. Navedo, Y. Takeda, M. Nieves‐Cintrón, J. Molkentin, L. Santana, Elevated Ca2+ sparklet activity  during  acute  hyperglycemia  and  diabetes  in  cerebral  arterial  smooth  muscle  cells,  Am  J  Physiol  Cell  Physiol, 298 (2010) C211‐220.  [52] A.P. Sanchez, K. Sharma, Transcription factors in the pathogenesis of diabetic nephropathy, Expert  reviews in molecular medicine, 11 (2009) e13.  [53]  A.V.  Zetterqvist,  L.M.  Berglund,  F.  Blanco,  E.  Garcia‐Vaz,  M.  Wigren,  P. Dunér, A.M. Andersson, F.  To,  P.  Spegel,  J.  Nilsson,  E.  Bengtsson,  M.F.  Gomez,  Inhibition  of  nuclear  factor  of  activated  T‐cells  (NFAT) suppresses accelerated atherosclerosis in diabetic mice, PLoS One, 8 (2013) e65020.  [54]  J.A.  Beckman,  A.B.  Goldfine,  M.B.  Gordon,  M.A.  Creager,  Ascorbate  restores  endothelium‐ dependent vasodilation impaired by acute hyperglycemia in humans, Circulation, 103 (2001) 1618‐1623.  [55]  T.  Nishikawa,  D.  Edelstein,  X.L.  Du,  S. Yamagishi, T. Matsumura, Y. Kaneda, M.A. Yorek, D. Beebe,  P.J.  Oates,  H.P.  Hammes,  I.  Giardino,  M.  Brownlee,  Normalizing  mitochondrial  superoxide  production  blocks three pathways of hyperglycaemic damage, Nature, 404 (2000) 787‐790.  [56]  Z.  Bagi,  A.  Koller,  G.  Kaley,  PPARgamma  activation,  by  reducing  oxidative  stress,  increases  NO  bioavailability in coronary arterioles of mice with Type 2 diabetes, Am J Physiol Heart Circ Physiol, 286  (2004) H742‐748.  [57] N. Erdei, Z. Bagi, I. Edes, G. Kaley, A. Koller, H2O2 increases production of constrictor prostaglandins  in  smooth  muscle  leading  to  enhanced  arteriolar  tone  in  Type  2  diabetic  mice,  American  journal  of  physiology. Heart and circulatory physiology, 292 (2007) H649‐656.  26   

Page 26 of 38

Ac ce p

te

d

M

an

us

cr

ip t

[58]  J.C.  Frisbee,  K.G.  Maier,  D.W.  Stepp,  Oxidant  stress‐induced  increase  in  myogenic  activation  of  skeletal  muscle  resistance  arteries  in  obese  Zucker  rats,  Am  J  Physiol  Heart  Circ  Physiol,  283  (2002)  H2160‐2168.  [59]  H.  Vlassara,  M.R.  Palace,  Diabetes  and  advanced  glycation  endproducts,  Journal  of  internal  medicine, 251 (2002) 87‐101.  [60]  A.  Stirban,  T.  Gawlowski,  M.  Roden,  Vascular  effects  of  advanced  glycation  endproducts:  Clinical  effects and molecular mechanisms, Mol Metab, 3 (2014) 94‐108.  [61]  V.  Jakus,  N.  Rietbrock,  Advanced  glycation  end‐products  and  the  progress  of  diabetic  vascular  complications, Physiological research / Academia Scientiarum Bohemoslovaca, 53 (2004) 131‐142.  [62]  N.  Ahmed,  P.J.  Thornalley,  Advanced  glycation  endproducts:  what  is  their  relevance  to  diabetic  complications?, Diabetes Obes Metab, 9 (2007) 233‐245.  [63] A.M. Schmidt, D. Stern, Atherosclerosis and diabetes: the RAGE connection, Curr Atheroscler Rep, 2  (2000) 430‐436.  [64]  J.  Su,  P.A.  Lucchesi,  R.A.  Gonzalez‐Villalobos,  D.I.  Palen,  B.M.  Rezk,  Y.  Suzuki,  H.A.  Boulares,  K.  Matrougui,  Role  of  advanced  glycation  end  products  with  oxidative  stress  in  resistance  artery  dysfunction in type 2 diabetic mice, Arterioscler Thromb Vasc Biol, 28 (2008) 1432‐1438.  [65] S. Schiekofer, M. Andrassy, J. Chen, G. Rudofsky, J. Schneider, T. Wendt, N. Stefan, P. Humpert, A.  Fritsche, M. Stumvoll, E. Schleicher, H.U. Haring, P.P. Nawroth, A. Bierhaus, Acute hyperglycemia causes  intracellular formation of CML and activation of ras, p42/44 MAPK, and nuclear factor kappaB in PBMCs,  Diabetes, 52 (2003) 621‐633.  [66]  A.  Bierhaus,  S.  Chevion,  M.  Chevion,  M.  Hofmann,  P.  Quehenberger,  T.  Illmer,  T.  Luther,  E.  Berentshtein,  H.  Tritschler,  M.  Muller,  P.  Wahl,  R.  Ziegler,  P.P.  Nawroth,  Advanced  glycation  end  product‐induced activation of NF‐kappaB is suppressed by alpha‐lipoic acid in cultured endothelial cells,  Diabetes, 46 (1997) 1481‐1490.  [67] K.C. David, R.H. Scott, G.F. Nixon, Advanced glycation endproducts induce a proliferative response  in  vascular  smooth  muscle  cells  via  altered  calcium  signaling,  Biochemical  pharmacology,  76  (2008)  1110‐1120.  [68] Y.M. Searls, R. Loganathan, I.V. Smirnova, L. Stehno‐Bittel, Intracellular Ca2+ regulating proteins in  vascular smooth muscle cells are altered with type 1 diabetes due to the direct effects of hyperglycemia,  Cardiovasc Diabetol, 9 (2010) 8.  [69] M. Barbagallo, J. Shan, P.K. Pang, L.M. Resnick, Glucose‐induced alterations of cytosolic free calcium  in cultured rat tail artery vascular smooth muscle cells, J Clin Invest, 95 (1995) 763‐767.  [70] T. Ohara, K.E. Sussman, B. Draznin, Effect of diabetes on cytosolic free Ca2+ and Na(+)‐K(+)‐ATPase  in rat aorta, Diabetes, 40 (1991) 1560‐1563.  [71]  R.  Wang,  Y.  Wu,  G.  Tang,  L.  Wu,  S.T.  Hanna,  Altered  L‐type  Ca(2+)  channel  currents  in  vascular  smooth muscle cells from experimental diabetic rats, Am J Physiol Heart Circ Physiol, 278 (2000) H714‐ 722.  [72] J.F. Pinho, M.A. Medeiros, L.S. Capettini, B.A. Rezende, P.P. Campos, S.P. Andrade, S.F. Cortes, J.S.  Cruz,  V.S.  Lemos,  Phosphatidylinositol  3‐kinase‐δ  up‐regulates  L‐type  Ca2+  currents  and  increases  vascular contractility in a mouse model of type 1 diabetes, Br J Pharmacol, 161 (2010) 1458‐1471.  [73] E. Fleischhacker, V.E. Esenabhalu, M. Spitaler, S. Holzmann, F. Skrabal, B. Koidl, G.M. Kostner, W.F.  Graier, Human diabetes is associated with hyperreactivity of vascular smooth muscle cells due to altered  subcellular Ca2+ distribution, Diabetes, 48 (1999) 1323‐1330.  [74]  G.J.  Lagaud,  E.  Masih‐Khan,  S.  Kai,  C.  van  Breemen,  G.P.  Dubé,  Influence  of  type  II  diabetes  on  arterial  tone  and  endothelial  function  in  murine  mesenteric  resistance  arteries,  J  Vasc  Res,  38  (2001)  578‐589.  [75]  E.B.  Okon,  T.  Szado,  I.  Laher,  B.  McManus,  C.  van  Breemen,  Augmented  contractile  response  of  vascular smooth muscle in a diabetic mouse model, J Vasc Res, 40 (2003) 520‐530.  27   

Page 27 of 38

Ac ce p

te

d

M

an

us

cr

ip t

[76]  Z.  Ungvari,  P.  Pacher,  V.  Kecskemeti,  G.  Papp,  L.  Szollár,  A.  Koller,  Increased  myogenic  tone  in  skeletal  muscle  arterioles  of  diabetic  rats.  Possible  role  of  increased  activity  of  smooth  muscle  Ca2+  channels and protein kinase C, Cardiovasc Res, 43 (1999) 1018‐1028.  [77]  M.  Pannirselvam,  W.B.  Wiehler,  T.  Anderson,  C.R.  Triggle,  Enhanced  vascular  reactivity  of  small  mesenteric arteries from diabetic mice is associated with enhanced oxidative stress and cyclooxygenase  products, Br J Pharmacol, 144 (2005) 953‐960.  [78]  C.N.  Scholfield,  T.M.  Curtis,  Heterogeneity  in  cytosolic  calcium  regulation  among  different  microvascular smooth muscle cells of the rat retina, Microvasc Res, 59 (2000) 233‐242.  [79] T.M. Curtis, E.H. Major, E.R. Trimble, C.N. Scholfield, Diabetes‐induced activation of protein kinase C  inhibits store‐operated Ca2+ uptake in rat retinal microvascular smooth muscle, Diabetologia, 46 (2003)  1252‐1259.  [80]  D.J.  Beech,  Ion  channel  switching  and  activation  in  smooth‐muscle  cells  of  occlusive  vascular  diseases, Biochem Soc Trans, 35 (2007) 890‐894.  [81] J.F. Evans, J.H. Lee, L. Ragolia, Ang‐II‐induced Ca(2+) influx is mediated by the 1/4/5 subgroup of the  transient receptor potential proteins in cultured aortic smooth muscle cells from diabetic Goto‐Kakizaki  rats, Mol Cell Endocrinol, 302 (2009) 49‐57.  [82]  C.M.  Steppan,  S.T.  Bailey,  S.  Bhat,  E.J.  Brown,  R.R.  Banerjee,  C.M.  Wright,  H.R.  Patel,  R.S.  Ahima,  M.A. Lazar, The hormone resistin links obesity to diabetes, Nature, 409 (2001) 307‐312.  [83] T.Y. Chuang, L.C. Au, L.C. Wang, L.T. Ho, D.M. Yang, C.C. Juan, Potential effect of resistin on the ET‐ 1‐increased reactions of blood pressure in rats and Ca2+ signaling in vascular smooth muscle cells, J Cell  Physiol, 227 (2012) 1610‐1618.  [84]  M.  Descorbeth,  M.B.  Anand‐Srivastava,  High  glucose  increases  the  expression  of  Gq/11alpha  and  PLC‐beta  proteins  and  associated  signaling  in  vascular  smooth  muscle  cells,  Am  J  Physiol  Heart  Circ  Physiol, 295 (2008) H2135‐2142.  [85]  M.  Mederos  y  Schnitzler,  U.  Storch,  T.  Gudermann,  AT1  receptors  as  mechanosensors,  Curr  Opin  Pharmacol, 11 (2011) 112‐116.  [86]  G.  Kauffenstein,  I.  Laher,  K.  Matrougui,  N.C.  Guérineau,  D.  Henrion,  Emerging  role  of  G  protein‐ coupled receptors in microvascular myogenic tone, Cardiovasc Res, 95 (2012) 223‐232.  [87]  A.D.  Hughes,  AT(1)‐signalling  in  vascular  smooth  muscle,  J  Renin  Angiotensin  Aldosterone  Syst,  1  (2000) 125‐130.  [88] Z. Guo, W. Su, S. Allen, H. Pang, A. Daugherty, E. Smart, M. Gong, COX‐2 up‐regulation and vascular  smooth  muscle  contractile  hyperreactivity  in  spontaneous  diabetic  db/db  mice,  Cardiovasc  Res,  67  (2005) 723‐735.  [89]  A.H.  Siddiqui,  T.  Hussain,  Enhanced  AT1  receptor‐mediated  vasocontractile  response  to  ANG  II  in  endothelium‐denuded  aorta  of  obese  Zucker  rats,  Am  J  Physiol  Heart  Circ  Physiol,  292  (2007)  H1722‐ 1727.  [90] K. Sharma, L. Deelman, M. Madesh, B. Kurz, E. Ciccone, S. Siva, T. Hu, Y. Zhu, L. Wang, R. Henning, X.  Ma, G. Hajnoczky, Involvement of transforming growth factor‐beta in regulation of calcium transients in  diabetic vascular smooth muscle cells, Am J Physiol Renal Physiol, 285 (2003) F1258‐1270.  [91]  Z.  Bagi,  A.  Feher,  J.  Cassuto,  K.  Akula,  N.  Labinskyy,  G.  Kaley,  A.  Koller,  Increased  availability  of  angiotensin AT 1 receptors leads to sustained arterial constriction to angiotensin II in diabetes ‐ role for  Rho‐kinase activation, Br J Pharmacol, 163 (2011) 1059‐1068.  [92] M.A. Carrillo‐Sepulveda, T. Matsumoto, K.P. Nunes, R.C. Webb, Therapeutic implications of peptide  interactions  with  G‐protein‐coupled  receptors  in  diabetic  vasculopathy,  Acta  Physiol  (Oxf),  211  (2014)  20‐35.  [93]  M.  Rodríguez‐Moyano,  I.  Díaz,  N.  Dionisio,  X.  Zhang,  J.  Avila‐Medina,  E.  Calderón‐Sánchez,  M.  Trebak,  J.A.  Rosado,  A.  Ordóñez,  T.  Smani,  Urotensin‐II  promotes  vascular  smooth  muscle  cell 

28   

Page 28 of 38

Ac ce p

te

d

M

an

us

cr

ip t

proliferation through store‐operated calcium entry and EGFR transactivation, Cardiovasc Res, 100 (2013)  297‐306.  [94] M. Maceyka, K.B. Harikumar, S. Milstien, S. Spiegel, Sphingosine‐1‐phosphate signaling and its role  in disease, Trends Cell Biol, 22 (2012) 50‐60.  [95] T.E. Fox, M.C. Bewley, K.A. Unrath, M.M. Pedersen, R.E. Anderson, D.Y. Jung, L.S. Jefferson, J.K. Kim,  S.K. Bronson, J.M. Flanagan, M. Kester, Circulating sphingolipid biomarkers in models of type 1 diabetes,  J Lipid Res, 52 (2011) 509‐517.  [96]  T.  Imasawa,  K.  Koike,  I.  Ishii,  J.  Chun,  Y.  Yatomi,  Blockade  of  sphingosine  1‐phosphate  receptor  2  signaling  attenuates  streptozotocin‐induced  apoptosis  of  pancreatic  beta‐cells,  Biochem  Biophys  Res  Commun, 392 (2010) 207‐211.  [97] C. Waeber, N. Blondeau, S. Salomone, Vascular sphingosine‐1‐phosphate S1P1 and S1P3 receptors,  Drug News Perspect, 17 (2004) 365‐382.  [98]  J.N.  Lorenz,  L.J.  Arend,  R.  Robitz,  R.J.  Paul,  A.J.  MacLennan,  Vascular  dysfunction  in  S1P2  sphingosine  1‐phosphate  receptor  knockout  mice,  Am  J Physiol Regul Integr Comp Physiol, 292 (2007)  R440‐446.  [99] T. Hofmann, A.G. Obukhov, M. Schaefer, C. Harteneck, T. Gudermann, G. Schultz, Direct activation  of human TRPC6 and TRPC3 channels by diacylglycerol, Nature, 397 (1999) 259‐263.  [100] K.P. Hopson, J. Truelove, J. Chun, Y. Wang, C. Waeber, S1P activates store‐operated calcium entry  via  receptor‐  and  non‐receptor‐mediated  pathways  in  vascular  smooth  muscle  cells,  Am  J  Physiol  Cell  Physiol, 300 (2011) C919‐926.  [101] R.A. Pulver, P. Rose‐Curtis, M.W. Roe, G.C. Wellman, K.M. Lounsbury, Store‐operated Ca2+ entry  activates the CREB transcription factor in vascular smooth muscle, Circ Res, 94 (2004) 1351‐1358.  [102]  A. GUERRERO‐HERNANDEZ, L. GOMEZ‐VIQUEZ, G. GUERRERO‐SERNA, e. al., Ryanodine receptors  in smooth muscle, FRONTIERS IN BIOSCIENCE, 7 (2002) D1676‐D1688.  [103] T. Vaithianathan, D. Narayanan, M.T. Asuncion‐Chin, L.H. Jeyakumar, J. Liu, S. Fleischer, J.H. Jaggar,  A.M.  Dopico,  Subtype  identification  and  functional  characterization  of  ryanodine  receptors  in  rat  cerebral artery myocytes, Am J Physiol Cell Physiol, 299 (2010) C264‐278.  [104]  E.  Tam,  D.  Ferguson,  D.  Bielefeld,  J.  Lorenz,  R.  Cohen,  R.  Pun,  Norepinephrine‐mediated  calcium  signaling is altered in vascular smooth muscle of diabetic rat, Cell Calcium, 21 (1997) 143‐150.  [105]  L.  Ma,  B.  Zhu,  X.  Chen,  J.  Liu,  Y.  Guan,  J.  Ren,  Abnormalities  of  sarcoplasmic  reticulum  Ca2+  mobilization in aortic smooth muscle cells from streptozotocin‐induced diabetic rats, Clin Exp Pharmacol  Physiol, 35 (2008) 568‐573.  [106] A. Rueda, M. Fernández‐Velasco, J.P. Benitah, A.M. Gómez, Abnormal Ca(2+) Spark/STOC Coupling  in Cerebral Artery Smooth Muscle Cells of Obese Type 2 Diabetic Mice, PLoS One, 8 (2013) e53321.  [107]  M.  McGahon,  D.  Dash,  A.  Arora,  N.  Wall,  J.  Dawicki,  D.  Simpson,  C.  Scholfield,  J.  McGeown,  T.  Curtis, Diabetes downregulates large‐conductance Ca2+‐activated potassium beta 1 channel subunit in  retinal arteriolar smooth muscle, Circ Res, 100 (2007) 703‐711.  [108] L. Dong, Y. Zheng, D. Van Riper, R. Rathore, Q. Liu, H. Singer, Y. Wang, Functional and molecular  evidence  for  impairment  of  calcium‐activated  potassium  channels  in  type‐1  diabetic  cerebral  artery  smooth muscle cells, J Cereb Blood Flow Metab, 28 (2008) 377‐386.  [109] R. Abbate, E. Mannucci, G. Cioni, C. Fatini, R. Marcucci, Diabetes and sex: from pathophysiology to  personalized medicine, Intern Emerg Med, 7 Suppl 3 (2012) S215‐219.  [110] R. Brenner, G. Peréz, A. Bonev, D. Eckman, J. Kosek, S. Wiler, A. Patterson, M. Nelson, R. Aldrich,  Vasoregulation  by  the  beta1  subunit  of  the  calcium‐activated  potassium  channel,  Nature,  407  (2000)  870‐876.  [111] G. Amberg, A. Bonev, C. Rossow, M. Nelson, L. Santana, Modulation of the molecular composition  of large conductance, Ca(2+) activated K(+) channels in vascular smooth muscle during hypertension, J  Clin Invest, 112 (2003) 717‐724.  29   

Page 29 of 38

Ac ce p

te

d

M

an

us

cr

ip t

[112] T. Lu, D. Ye, T. He, X.L. Wang, H.L. Wang, H.C. Lee, Impaired Ca2+‐dependent activation of large‐ conductance Ca2+‐activated K+ channels in the coronary artery smooth muscle cells of Zucker Diabetic  Fatty rats, Biophys J, 95 (2008) 5165‐5177.  [113] Y. Wang, H.T. Zhang, X.L. Su, X.L. Deng, B.X. Yuan, W. Zhang, X.F. Wang, Y.B. Yang, Experimental  diabetes  mellitus  down‐regulates  large‐conductance  Ca2+‐activated  K+  channels  in  cerebral  artery  smooth muscle and alters functional conductance, Curr Neurovasc Res, 7 (2010) 75‐84.  [114]  H.  Li,  Q.  Chai,  D.D.  Gutterman,  Y.  Liu,  Elevated  glucose  impairs  cAMP‐mediated  dilation  by  reducing Kv channel activity in rat small coronary smooth muscle cells, American journal of physiology.  Heart and circulatory physiology, 285 (2003) H1213‐1219.  [115] Y. Liu, K. Terata, Q. Chai, H. Li, L.H. Kleinman, D.D. Gutterman, Peroxynitrite inhibits Ca2+‐activated  K+  channel  activity  in  smooth  muscle  of  human  coronary  arterioles,  Circulation  research,  91  (2002)  1070‐1076.  [116]  X.  Tang,  M.  Garcia,  S.  Heinemann,  T.  Hoshi,  Reactive  oxygen  species  impair  Slo1  BK  channel  function by altering cysteine‐mediated calcium sensing, Nat Struct Mol Biol, 11 (2004) 171‐178.  [117]  M.A.  Soto,  C.  Gonzalez,  E.  Lissi,  C.  Vergara,  R.  Latorre,  Ca(2+)‐activated  K+  channel  inhibition  by  reactive oxygen species, American journal of physiology. Cell physiology, 282 (2002) C461‐471.  [118] T.J. DiChiara, P.H. Reinhart, Redox modulation of hslo Ca2+‐activated K+ channels, J Neurosci, 17  (1997) 4942‐4955.  [119] R. Bychkov, K. Pieper, C. Ried, M. Milosheva, E. Bychkov, F.C. Luft, H. Haller, Hydrogen peroxide,  potassium  currents,  and  membrane  potential  in  human  endothelial  cells,  Circulation,  99  (1999)  1719‐ 1725.  [120]  T.  Lu,  Q.  Chai,  L.  Yu,  L.V.  d'Uscio,  Z.S.  Katusic,  T.  He,  H.C.  Lee,  Reactive  oxygen  species  signaling  facilitates  FOXO‐3a/FBXO‐dependent  vascular  BK  channel  beta1  subunit  degradation  in  diabetic  mice,  Diabetes, 61 (2012) 1860‐1868.  [121]  L.  Borbouse,  G.M.  Dick,  S.  Asano,  S.B.  Bender,  U.D.  Dincer,  G.A.  Payne,  Z.P.  Neeb,  I.N.  Bratz,  M.  Sturek,  J.D.  Tune,  Impaired  function of coronary BK(Ca) channels in metabolic syndrome, Am J Physiol  Heart Circ Physiol, 297 (2009) H1629‐1637.  [122]  T.A.  McGowan,  K.  Sharma,  Regulation  of  inositol  1,4,5‐trisphosphate  receptors  by  transforming  growth  factor‐beta:  implications  for  vascular  dysfunction  in  diabetes,  Kidney  Int  Suppl,  77  (2000)  S99‐ 103.  [123]  C.  Li,  X.  Wang,  H.  Vais,  C.B.  Thompson,  J.K.  Foskett,  C.  White,  Apoptosis  regulation  by  Bcl‐x(L)  modulation of mammalian inositol 1,4,5‐trisphosphate receptor channel isoform gating, Proc Natl Acad  Sci U S A, 104 (2007) 12565‐12570.  [124] E.F. Eckenrode, J. Yang, G.V. Velmurugan, J.K. Foskett, C. White, Apoptosis protection by Mcl‐1 and  Bcl‐2  modulation  of  inositol  1,4,5‐trisphosphate  receptor‐dependent  Ca2+  signaling,  J  Biol  Chem,  285  (2010) 13678‐13684.  [125] G.V. Velmurugan, C. White, Calcium homeostasis in vascular smooth muscle cells is altered in type  2  diabetes  by  Bcl‐2  protein  modulation  of  InsP3R  calcium  release  channels,  Am  J  Physiol  Heart  Circ  Physiol, 302 (2012) H124‐134.  [126] C. White, C. Li, J. Yang, N.B. Petrenko, M. Madesh, C.B. Thompson, J.K. Foskett, The endoplasmic  reticulum gateway to apoptosis by Bcl‐X(L) modulation of the InsP3R, Nat Cell Biol, 7 (2005) 1021‐1028.  [127] D. Narayanan, A. Adebiyi, J.H. Jaggar, Inositol trisphosphate receptors in smooth muscle cells, Am J  Physiol Heart Circ Physiol, 302 (2012) H2190‐2210.  [128] R. Ye, M. Ni, M. Wang, S. Luo, G. Zhu, R.H. Chow, A.S. Lee, Inositol 1,4,5‐trisphosphate receptor 1  mutation  perturbs  glucose  homeostasis  and  enhances  susceptibility  to  diet‐induced  diabetes,  J  Endocrinol, 210 (2011) 209‐217.  [129] A.K. Cardozo, F. Ortis, J. Storling, Y.M. Feng, J. Rasschaert, M. Tonnesen, F. Van Eylen, T. Mandrup‐ Poulsen, A. Herchuelz, D.L. Eizirik, Cytokines downregulate the sarcoendoplasmic reticulum pump Ca2+  30   

Page 30 of 38

Ac ce p

te

d

M

an

us

cr

ip t

ATPase  2b  and  deplete  endoplasmic  reticulum  Ca2+,  leading  to  induction  of  endoplasmic  reticulum  stress in pancreatic beta‐cells, Diabetes, 54 (2005) 452‐461.  [130]  E.A.  Mokelke,  M.  Wang,  M.  Sturek,  Exercise  training  enhances  coronary  smooth  muscle  cell  sodium‐calcium exchange activity in diabetic dyslipidemic Yucatan swine, Ann N Y Acad Sci, 976 (2002)  335‐337.  [131] E. Mokelke, N. Dietz, D. Eckman, M. Nelson, M. Sturek, Diabetic dyslipidemia and exercise affect  coronary tone and differential regulation of conduit and microvessel K+ current, Am J Physiol Heart Circ  Physiol, 288 (2005) H1233‐1241.  [132] G. Mathur, B. Noronha, E. Rodrigues, G. Davis, The role of angiotensin II type 1 receptor blockers in  the prevention and management of diabetes mellitus, Diabetes Obes Metab, 9 (2007) 617‐629.  [133]  T.  Matsumoto,  K.  Ishida,  K.  Taguchi,  T.  Kobayashi,  K.  Kamata,  Losartan  normalizes  endothelium‐ derived  hyperpolarizing  factor‐mediated  relaxation  by  activating  Ca2+‐activated  K+  channels  in  mesenteric artery from type 2 diabetic GK rat, J Pharmacol Sci, 112 (2010) 299‐309.  [134]  L.  Dong,  M.J.  Xie,  P.  Zhang,  L.L.  Ji,  W.C.  Liu,  M.Q.  Dong,  F.  Gao,  Rotenone  partially  reverses  decreased  BK  Ca  currents  in  cerebral  artery  smooth  muscle  cells  from  streptozotocin‐induced  diabetic  mice, Clin Exp Pharmacol Physiol, 36 (2009) e57‐64.  [135]  D.M.  Zhang,  T.  He,  Z.S.  Katusic,  H.C.  Lee,  T.  Lu,  Muscle‐specific  f‐box  only  proteins  facilitate  bk  channel beta(1) subunit downregulation in vascular smooth muscle cells of diabetes mellitus, Circ Res,  107 (2010) 1454‐1459.  [136]  T.  Lu,  D.M.  Zhang,  X.L.  Wang,  T.  He,  R.X.  Wang,  Q.  Chai,  Z.S.  Katusic,  H.C.  Lee,  Regulation  of  coronary  arterial  BK  channels  by  caveolae‐mediated  angiotensin  II  signaling  in  diabetes  mellitus,  Circ  Res, 106 (2010) 1164‐1173.  [137] W.G. Mayhan, J.F. Mayhan, H. Sun, K.P. Patel, In vivo properties of potassium channels in cerebral  blood vessels during diabetes mellitus, Microcirculation, 11 (2004) 605‐613.  [138] K. Sachidanandam, J.R. Hutchinson, M.M. Elgebaly, E.M. Mezzetti, A.M. Dorrance, K. Motamed, A.  Ergul, Glycemic control prevents microvascular remodeling and increased tone in type 2 diabetes: link to  endothelin‐1, Am J Physiol Regul Integr Comp Physiol, 296 (2009) R952‐959.   

31   

Page 31 of 38

FIGURE LEGENDS Figure 1. Properties of spontaneous Ca2+ sparks and STOCs in cerebral artery VSCMs of

ip t

diabetic male and females mice. Bar graphs of Ca2+ spark frequency (A), Ca2+ spark amplitude

cr

(B), STOC frequency (C), STOC amplitude (D), calculated STOC/Spark frequency ratio (E) and STOC/Spark amplitude ratio (F). Values represent mean ± S.E. of sparks recorded in 43 and 41

us

VSMCs of control (+/+, solid white bars) and diabetic (db/db, solid green bars) male animals vs.

an

35 and 32 VSMCs of control (+/+, dashed white bars) and diabetic (db/db, dashed green bars) female mice. In the case of STOCs, the numbers of recorded VSMCs were 9 and 8 for control

M

and diabetic male mice, respectively; they numbered 11 and 15 for control and diabetic female

d

mice, respectively. * P< 0.05 with respect to male +/+; ** P<0.01 with respect to male +/+.

te

Figure 2. Modifications in the function and/or expression levels of endothelial and vascular

Ac ce p

Ca2+ signaling proteins associated with the diabetic condition. This figure summarizes our current view of more consistent alterations of Ca2+ handling proteins on both endothelial and VSMC levels associated with diabetes. Arrows indicate an increase (blue) or decrease (red) in the expression/functional activity of Ca2+ handling and related proteins of endothelial and vascular smooth muscle cells. AGEs, advanced glycation end products; ATAR, type A of the angiotensin II receptors; BK channels, big conductance Ca2+ activated K+ channels; cGMP, cyclic guanosine monophosphate; eNOS, endothelial nitric oxide synthase; ETAR, type A endothelin-1 receptor; GC, guanylate cyclase; iNOS, inducible endothelial nitric oxide synthase; IP3R, inositol 1,4,5-trisphosphate receptors; NF-kB, nuclear factor kB; NFAT, nuclear factor of activated T cells; NCX, Na+/Ca2+ exchanger; NO, nitric oxide; ROS, reactive oxygen species; 32   

Page 32 of 38

ROCs, receptor operated Ca2+ channels; RyR, ryanodine receptors; SERCA pump, sarco/endoplasmic reticulum Ca2+ ATPase; SOCs, store operated Ca2+ channels; TRPs, transient

Ac ce p

te

d

M

an

us

cr

ip t

receptor potential ion channels; VDCCs, voltage-dependent Ca2+ channels.

33   

Page 33 of 38

i cr cultured human endothelium ↓WB(eNOS) (Coronary) ↑WB(eNOS) (aorta) (umbilical vein) ↔WB(eNOS)

DR-BB db/db mice

↑WB ↓FA(HAR) ↓FA(PXR) ↑FA(ETR, ATR)

TRP/ SOCE

GotoKakizaki rats Diabetic swine

RyR

IP3R

VDCCs

Mesenteric ↔RT(eNOS) artery Coronary artery Aorta mammary ↓WB, FA artery (eNOS) ↑WB (iNOS) Mesenteric artery Cultured aorta

SERCA pump

↓IC

↓IC↓FA

↑FA

↑WB ↓WB

↓WB ↓FA

↑FA

↓WB ↓FA

↓FA ↓FA↔WB ↓FA,WB ↓FA ↓FA,IC, RT ↔RT ↔FA

↓FA

↓FA, IC

↑WB ↑RT, WB ↓FA,↔WB

↓FA,↓WB

↓FA, ↓WB

↓WB ↑FA, ↔WB

↓WB

[68, 72, 90, 105] [71] [120, 136] [137] [107] [79] [24] [40]

[68] [48, 88, 125]

↑FA

[51, 106] [77]

↔WB

↓FA ↔WB

[112] [89] [37]

↓FA

[133, 138]

↑FA(ATR)

↑FA, WB (TRPCs)

[81] ↓FA

↓FA ↓FA

34   

↓FA, IC

↑FA

↑WB (ETR) ↑FA(ATR)

Ref.

[84] [68] [135]

↓IC

↓FA↔WB ↓FA,WB

↓FA(ATR)

↑FA(ATR) ↑FA(5-HTR)

NCX

[36] [47] [26, 27]

↓ FA ↑FA,IC, RT,WB (iNOS)

Aorta Aorta

Femoral artery Coronary artery

BK channel (βsubunit)

[38]

Cerebral artery

Zucker diabetic rats Human type 2 DM patients

BK channel (α-subunit)

↑FA

ce

Tail artery Coronary artery Cerebral artery Retinal arterioles Endothelium Aorta

COX2

pt

A10 (aorta) A7r5 (aorta) Human cerebral artery ↑WB, RT Mouse (eNOS) endothelium (microvessels) Aorta

Ac

Pancreatectomy zed rats

GPCRs

an

High glucose levels

STZ-induced DM

NOS

M

Vascular cell type

ed

Experimental model

us

TABLES

Page 34 of 38

↓FA

[131] [130]

i cr us

Table 1. Modifications in the function and/or expression levels of main vascular Ca2+ signaling proteins related to the diabetic

an

condition. Arrows indicate decreased (↓), increased (↑) or no change (↔) in the expression levels (determined by immunocytochemistry, [IC]; quantitative real time PCR, [RT]; and Western Blot, [WB]) and/or functional activity (FA) of following

M

proteins: 5-HTR, serotonin receptor; ATR, Angiotensin II receptor; BK channels, big conductance Ca2+ activated K+ channels; COX1/2, cyclooxygenase type 1/2; eNOS, endothelial nitric oxide synthase; ETR, Endothelin-1 receptor; HAR, histamine receptor;

ed

iNOS, inducible endothelial nitric oxide synthase; IP3R, inositol 1,4,5-trisphosphate receptors; NCX, Na+/Ca2+ exchanger; PXR, purinergic receptor; RyR, ryanodine receptors; SERCA pump, sarco/endoplasmic reticulum Ca2+ ATPase; SOCE, store-operated Ca2+

Ac

ce

pt

entry; TRPs, transient receptor potential ion channels; VDCCs, voltage-dependent Ca2+ channels.

35   

Page 35 of 38

*Graphical Abstract

Ac ce p

te

d

M

an

us

cr

ip t

GRAPHICAL ABSTRACT

Page 36 of 38

Ac ce p

te

d

M

an

us

cr

ip t

Figure1

Page 37 of 38

Ac

ce

pt

ed

M

an

us

cr

i

Figure2

Page 38 of 38