Class I phosphoinositide 3-kinase (PI3K) regulatory subunits and their roles in signaling and disease

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Class I phosphoinositide 3-kinase (PI3K) regulatory subunits and their roles in signaling and disease Manoj K. Rathinaswamy, John E. Burke∗ Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8W 2Y2, Canada

A R T IC LE I N F O

ABS TRA CT

Keywords: Phosphoinositide 3-kinase PIK3CA PIK3R1 PI3K p110 p85

The Class I phosphoinositide 3-kinases (PI3Ks) are a group of heterodimeric lipid kinases that regulate crucial cellular processes including proliferation, survival, growth, and metabolism. The diversity in functions controlled by the various catalytic isoforms (p110α, p110β, p110δ, and p110γ) depends on their abilities to be activated by distinct stimuli such as receptor tyrosine kinases (RTKs), G-protein coupled receptors (GPCRs), and the Ras family of small G-proteins. A major factor determining the ability of each p110 enzyme to be activated is the presence of regulatory binding partners. Given the overwhelming evidence for the involvement of PI3Ks in diseases such as cancer, inflammation, immunodeficiency and diabetes, an understanding of how these regulatory proteins influence PI3K function is essential. This article highlights research deciphering the role of regulatory subunits in PI3K signaling and their involvement in human disease.

1. Introduction A cell's survival and potential to proliferate is contingent on its ability to sense and transduce external signals. One of the key methods of transduction is through the generation of phosphoinositide lipids at the plasma membrane. Many important physiological processes including cell division, metabolism and motility are regulated by a second-messenger phospholipid called phosphatidylinositol-3,4,5 trisphosphate (PIP3), which is generated by the phosphorylation of the 3′ hydroxyl group on the inositol head group of phosphatidylinositol-4,5-bisphosphate (PIP2). This lipid is produced in response to external stimuli by the action of kinases called class I phosphoinositide-3 kinases (PI3Ks). PIP3 is sensed by many downstream effectors which in turn results in their recruitment to the membrane and the activation of their downstream targets (Bilanges et al., 2019). One of the most well studied PIP3 effectors is the protein kinase Akt, which recognizes PIP3 through its pleckstrin homology (PH) domain, which in turn relieves an autoinhibitory interaction between the PH and kinase domains (Lučić et al., 2018). Akt phosphorylates numerous targets including mTOR Complex1 activating protein TSC2, glycogen synthase kinase 3β (GSK3β) (Hermida et al., 2017) and FOXO family transcription factors, which control cellular processes associated with growth, survival, and metabolism. Other PIP3 effectors include Guanine Nucleotide Exchange factors (P-Rex1, Vav), GTPase activating proteins (ARAP3) and cytoskeletal proteins (WAVE2) which regulate movement and structural integrity (Balla, 2013; Fruman et al., 2017). All of the class I PI3Ks form heterodimeric protein complexes composed of a catalytic p110 subunit and a regulatory subunit. The different p110 isoforms of class I PI3Ks are subdivided into two distinct subclasses composed of three class IA (p110α, p110β, p110δ) isoforms and a single class IB isoform (p110γ). The p110 catalytic subunit has five well characterized domains; an N-terminal Adaptor

∗

Corresponding author. E-mail address: [email protected] (J.E. Burke).

https://doi.org/10.1016/j.jbior.2019.100657 Received 1 September 2019; Received in revised form 23 September 2019; Accepted 25 September 2019 2212-4926/ © 2019 Published by Elsevier Ltd.

Please cite this article as: Manoj K. Rathinaswamy and John E. Burke, Advances in Biological Regulation, https://doi.org/10.1016/j.jbior.2019.100657

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Fig. 1. Domain organization of Class I PI3K catalytic and regulatory subunits. The catalytic p110 subunit has five domains- Adaptor Binding Domain (ABD), Ras Binding Domain (RBD), Helical domain and a bilobed Kinase domain. The class IA p110 isoforms associate with p85 or p85-like regulatory subunits. p85 is composed of a Src Homology 3 (SH3) domain, a BH domain and two Src Homology 2 (SH2) domains separated by an inter-SH2 (iSH2) domain. The p110γ isoform binds to p101 or p84/p87 regulatory subunits for which the domain organizations are unknown.

Binding Domain (ABD), a Ras Binding domain (RBD), a C2 domain, a helical domain, and a bi-lobal kinase domain which is homologous to that of other lipid kinases (Fig. 1.) (Burke, 2018; Vadas et al., 2011; Walker et al., 1999). The different p110 isoforms have very distinct expression patterns in human cells and tissues. While p110α and p110β are ubiquitously expressed, p110δ and p110γ are primarily expressed in immune cells and a few select tissues such as neurons and the heart (Eickholt et al., 2007; Okkenhaug, 2013; Perino et al., 2011). Given the essential cellular roles of PIP3, aberrations in p110 signalling are common in human disease. Intriguingly, multiple disease states are caused both by overactivation and inactivation of PI3K signalling, highlighting the importance of properly tuning PI3K output (Fruman et al., 2017). Activating mutations in p110α are frequent in malignant tumors (Samuels et al., 2004), with the gene encoding p110α, PIK3CA, being the 2nd most frequented oncogene in human cancer. Many of these mutations are also found in overgrowth syndromes (Madsen et al., 2018; Lindhurst et al., 2012; Rivière et al., 2012). Activating mutations in p110δ manifest in primary immunodeficiencies called Activated PI3K Delta Syndrome (APDS) (Angulo et al., 2013; Lucas et al., 2016, 2014a). While mutations in p110β and p110γ are less common in disease, they both still play important roles in multiple disease states. The activity of p110β is a major driver of PTEN-deficient and castrate-resistant prostate cancers (Jia et al., 2008), and p110γ plays important roles in inflammation (Hirsch et al., 2000), the tumor immune environment (Kaneda et al., 2016), and cardiovascular disease (Patrucco et al., 2004). Multiple PI3K inhibitors have entered the clinic targeting a variety of blood cancers, with numerous clinical trials also ongoing for solid tumors (Bertacchini et al., 2018; Hanker et al., 2019; Ricciardi et al., 2017). Such widespread involvement of PI3K signaling in disease underscores the need for mechanisms to keep PIP3 levels under tight control. The regulation of PI3K activity, and consequent PIP3 production, is driven by the interplay between two phenomena: signals arising from upstream activating stimuli and the interpretation of these signals by the PI3K catalytic and regulatory components. PI3Ks are recruited to the membrane directly by inputs from three major families of signaling proteins: Ras superfamily of small GTPases, G-protein coupled receptors (GPCRs), and Receptor Tyrosine Kinases (RTKs) (Fig. 2.) (Burke and Williams, 2015; Vanhaesebroeck et al., 2010). Activated small GTPases bind to the Ras-binding domain of all p110s and enhance membrane recruitment (Buckles et al., 2017; Pacold et al., 2000; Rodriguez-Viciana et al., 1994; Siempelkamp et al., 2017). The p110α, p110δ, and p110γ isoforms are activated by the Ras subfamily proteins while p110β is activated by members of the Rho GTPase subfamily (Fritsch et al., 2013). GPCR activation of PI3K is mediated by Gβγ subunits that can bind and activate both p110β and p110γ (Kurosu et al., 1997; Stephens et al., 1994). All class IA PI3Ks are able to be recruited and activated at the membrane by phosphorylated tyrosines on RTKs and their adaptor proteins (Carpenter et al., 1993). This diversity in the ability of various PI3K isoforms to differentially sense signaling inputs is key to their broad and crucial physiological roles. An important determinant of these diverse sensing capabilities are the regulatory partners that are associated with the catalytic subunits. All class IA PI3Ks exist as a complex with a p85 or p85-like regulatory subunit. The class IB PI3K p110γ, binds to one of two regulatory proteins, p101 or p84/p87. Given the widespread involvement of PI3Ks in disease, an understanding of the molecular details of these regulatory subunits and their 2

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Fig. 2. Diverse modes of Class I PI3K activation. A. Class IA PI3Ks are directly activated by receptor tyrosine kinases (RTKs), small GTPases (p110α, p110δ, and p110γ are activated by Ras; p110β is activated by Rho GTPases) and G-protein coupled receptors. The p110β isoform is directly activated by GPCRs. B. The activation of class IB PI3K is mediated by different adaptor proteins. GPCRs can activate both p110γ bound to p84 or p101, with p101 preferentially activated. The p110γ isoform can also be indirectly activated by IgE through Protein Kinase C, by Toll-like receptors through small GTPase Rab8 and by RTKs through Ras.

influence on isoform-specific PI3K activation can potentially open up novel avenues for targeted therapy.

2. Class IA PI3K regulatory subunits In mammals, the class IA catalytic subunits p110α, p110β, and p110δ interact with five regulatory proteins p85α, p55α, p50α, p85β, and p55γ which are encoded by three genes, PIK3R1, PIK3R2 and PIK3R3, broadly commonly classified as p85s. PIK3R1 can give rise to p85α and two more splice variants, p50α and p55α, while PIK3R2 and PIK3R3 encode p85β and p55γ respectively. All five p85 family proteins contain two Src homology domains (nSH2 and cSH2) separated by a coiled-coil inter-SH2 domain (iSH2) (Fig. 1.). The p85α and p85β proteins have two additional domains at the N-terminus of the SH2 domains: an SH3 domain and a Bcr Homology (BH) domain. The SH3 domain is proposed to mediate interactions with proteins containing PXXP motifs. The BH domain of p85 shows sequence similarities to Rho GTPase activating proteins (GAPs). The other p85 isoforms (p50 and p55) do not possess these two domains. Instead, p55s have a ~30 amino acid extension, while p50 has a shorter 6 amino acid extension at their N-termini. p85s are expressed ubiquitously in all tissues while the p55/p50 subunits are expressed in abundance in the brain, liver, kidney and muscles (Inukai et al., 1996). The complex between the p110 subunits of class IA PI3Ks and regulatory subunits is mediated by the tight interaction between the ABD domain of p110 and the iSH2 coiled coil of the regulatory subunits (Fig. 3.) (Miled et al., 2007). The interaction with regulatory subunits mediates three key functions, it stabilizes p110 subunits, it inhibits activity, and it allows for activation downstream of phosphorylated receptors and adaptors (Backer, 2010; Yu et al., 1998a, 1998b). Mediating the activation downstream of RTKs are the two SH2 domains, which are binders of phosphorylated tyrosine (pYXXM) motifs containing a methionine in the 3rd position (Songyang et al., 1993). It has been shown that while nSH2 prefers a hydrophobic residue immediately after the pY, the cSH2 does not have a preference at this position. The cSH2 appears to have higher affinity for many pYXXM motifs (Klippel et al., 1992), and can act as a template for the nSH2 binding to bisphosphorylated receptors. Such YXXM motifs exist on upstream activators of PI3Ks including membrane receptors (Insulin receptor, Platelet-derived growth factor receptor, etc.) and their adaptors (i.e. Insulin Receptor Substrate 1). The SH2 domains mediate the inhibition of p110 through a number of reversible inhibitory interactions (Fig. 3.). These interactions exist between the nSH2 and the C2, the helical and kinase domains of all class IA p110s (Burke et al., 2011; Burke and Williams, 2013; Mandelker et al., 2009), and between the cSH2 and the C-lobe of the kinase domains of p110β and p110δ (Burke et al., 2011; Zhang et al., 2011). The cSH2 does not bind to p110α due to a loop extension that disrupts this interface. The iSH2 also forms inhibitory contacts with the C2 domains of all p110 subunits, with this interface proposed to be slightly weaker in the p110β isoform (Dbouk et al., 2010). The binding of nSH2 and cSH2 domains to the phosphotyrosines on RTKs and RTK adaptors relieves these reversible inhibitory contacts and leads to PI3K activation (Burke et al., 2012). Given the critical involvement of p85 isoforms in mediating PI3K activation downstream of insulin signalling (Shepherd et al., 1998), deletions of PIK3R1 and/or PIK3R2 mice have been shown to cause hypoglycemia, heightened insulin sensitivity, muscle abnormalities, and liver necrosis. (Fruman et al., 2000; Ueki et al., 2002). The different p110 class IA isoforms can form a total of 15 distinct regulatory complexes; however, there has been limited data defining if certain complexes are preferred. Quantitative analysis of complex formation has revealed that p110α and p110β do not appear to differentiate between p85α and p85β, while p110δ preferentially binds p85α (Tsolakos et al., 2018). In addition to its role in p110 regulation, there is also evidence for the existence of monomeric p85α that can compete with heterodimeric p85s for RTKs, and regulate other lipid signalling enzymes (Cheung et al., 2015). Further study will be needed to fully understand the mechanisms that control complex formation of different PI3K regulatory complexes. 3

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Fig. 3. p85 SH2 domains mediate PI3K activation downstream of Receptor Tyrosine Kinases. A. Domain schematic of the interactions between p85 and p110 subunits for class IA PI3Ks. Phosphorylation on the SH2 domains by protein kinases PKC, Abl, Lck, Src and IκB is indicated on the schematic. B. The p110 subunit of class IA PI3Ks is inhibited by p85 through inhibitory interfaces with the SH2 and inter-SH2 domains, as shown by the wiring diagram. The nSH2 forms inhibitory contacts with the helical, C2 and kinase domains. The cSH2 contacts the kinase domain of p110β and p110δ. The iSH2 forms a stabilizing interface with the ABD and an inhibitory interface with the C2 domain. The p110 domains are colored according to the domain schematic on a modeled structure of p110β [PDB: 2y3a (p110/p85 icHS2) and 3hhm (p85 nSH2)]. C. Activation of class IA PI3Ks downstream of RTKs. Inhibitory interactions are broken upon the binding of the SH2 domains to phosphotyrosines (pY) on activated RTKs, as indicated by a model of active p110β [PDBs- 2y3a (p110), 2iui (nSH2 bound to pY) and 5aul (cSH2 bound to pY)].

2.1. Post-translational modifications of class IA regulatory subunits Different class IA regulatory subunits can undergo numerous post-translational modifications, which in turn influence the activity of the associated catalytic subunit (Fig. 3.). In COS cells, PKC stimulation by phorbol esters has been shown to phosphorylate S361 (nSH2) and S652 (cSH2) on p85α, which disrupts binding of the SH2 domains to pYXXM motifs (Lee et al., 2011). Inhibitory phosphorylation can also occur on S690 in the cSH2, which is mediated by IκΒ kinase in response to starvation (Comb et al., 2012). There is also evidence that p110 subunits themselves can phosphorylate S608 in p85α which lowers PI3K activity (Dhand et al., 1994). PTMs on p85 can also putatively relieve inhibition of p110, with phosphorylation of Y688 in the cSH2 by Abl, Lck and Src potentially leading to activation through the nSH2 of PI3K bound to the phosphorylated cSH2 domain (Cuevas et al., 2001; 4

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Willebrand et al., 1998). In addition to phosphorylation, regulatory subunits can also be ubiquitinated which targets it for proteasomal degradation. In T-cells, the E3 ubiquitin ligase Cbl-b has been shown to modify the SH3 domain of p85α (Fang et al., 2001). The p110-free pool of p85β is controlled through ubiquitination, leading to degradation by the F-box protein FBXL2 which in turn enhances PI3K signalling (Kuchay et al., 2013). 2.2. p85s in disease 2.2.1. Cancer/development Given the central role of the PI3K pathway in growth, proliferation, and survival, activating mutations in p85 drive cancer progression and developmental disorders. Among cancer types, endometrial tumors show frequent heterozygous mutations in both PIK3R1 and PIK3R2 (Cheung et al., 2011; Urick et al., 2011). Many of these mutations manifest as point mutations, deletions, or truncations at inhibitory interfaces with p110 (Jaiswal et al., 2009; Philp et al., 2001). Increased PIK3R2 expression is found in breast and colon carcinomas and can induce oncogenic transformation of primary fibroblasts (Cortés et al., 2012). This activity of p85β is mediated equally by both p110α and p110β, and the tumors show enhanced basal Akt activation reminiscent of PTEN knockout cells (Cortés et al., 2012; Ito et al., 2014). Additionally, transformed fibroblasts display enhanced invasive properties which is thought to increase the metastatic potential of tumors driven by PIK3R2 overexpression (Cariaga-Martínez et al., 2014). In contrast to p85β, p85α has been shown to act as a tumor suppressor. In breast cancers, PIK3R1 ablation drives tumor progression mediated by p110α and leads to increased recruitment of p110-p85β to RTKs (Thorpe et al., 2017). Mutations in cSH2 (R649W, Y657*) that disrupt binding to pYXXM are observed in SHORT syndrome, a developmental disorder characterized by short stature, hyperextensibility of joints, ocular depression, Rieger anomaly, teething delay, and insulin resistance (Huang-Doran et al., 2016; Thauvin-Robinet et al., 2013). Activating mutations in nSH2 are also implicated in developmental disorders such as megalencephaly and polymicrogyria (Rivière et al., 2012). 2.2.2. Immunodeficiency PI3K signalling is essential for proper immune cell development. B-cells lacking PIK3R1 exhibit high levels of IgM on their cell surface which is consistent with immature pro-B cells, and this in turn results in an impaired immune response (Fruman et al., 1999). Patients with aberrations in PIK3R1 and consequent hyperactive PI3K signalling exhibit severe antibody deficiency in a condition known as Activated PI3K Delta Syndrome (APDS2) (Deau et al., 2014; Lucas et al., 2014b). These patients have a point mutation resulting in a splice defect, where exon 11 is removed corresponding to 434–475 in the iSH2 of p85α which results in disruption of the inhibitory interactions with p110 (Dornan et al., 2017). This deletion primarily hyperactivates p110δ but not p110α, thereby explaining the appearance of an immune phenotype as opposed to an oncogenic phenotype. APDS has been shown to also manifest concurrently with other p85-related diseases including SHORT syndrome, lymphadenopathy and microcephaly (Bravo García-Morato et al., 2017). 3. Class IB PI3K regulatory subunits The Class IB catalytic subunit p110γ associates with one of two regulatory subunits, p101 or p84/p87 (referred to as p84 for the rest of the text). These regulatory subunits are thought to arise from a gene duplication event in jawed vertebrates (Philippon et al., 2015). Among the class IB PI3Ks, p110γ/p84 has a more widespread expression while that of p110γ/p101 is restricted to myeloid cells (Shymanets et al., 2013). The highest expression of PI3Kγ is observed in immune tissues and cardiac muscle where the two regulatory subunits exhibit varying degrees of redundancy. The p101 and p84 proteins exhibit a sequence similarity of ~40%, and their domain architecture is unknown. Unlike p85 which inhibits the class IA PI3Ks in the absence of RTK activation, the regulatory partners of p110γ do not inhibit kinase activity and actually serve to potentiate activating signals. 3.1. p101 p101 (PIK3R5) was discovered in porcine neutrophils where it was found that the activation of p110γ by GPCR subunit Gβγ was increased by more than 100-fold by association with a 101 kDa protein (Stephens et al., 1997). Biochemical experiments have shown that downstream of GPCRs, the class IB heterodimer comprising p101 is significantly more activated by Gβγ subunits than that containing p84 (Fig. 2.) (Vadas et al., 2013). HDX-MS experiments have defined that the C-terminus of p101 drives the enhanced stimulation of p110γ/p101 by Gβγ (Vadas et al., 2013). The physiological role of p101 was best characterized in neutrophils where it is highly expressed, with mouse neutrophils lacking p101 exhibiting a 50% reduction in PIP3 accumulation in response to GPCR agonist fMLP (Deladeriere et al., 2015). These neutrophils exhibit reduced chemotaxis in response to stimulation which was attributed to defects in F-actin polymerization. In macrophages, a knockdown of p101 resulted in reduced V-CAM1 mediated adhesion in response to GPCR activating chemokines IL-8 and SDF-1α (Schmid et al., 2011). Stimulation by these chemokines resulted in increased membrane translocation of p110γ/p101 but not p110γ/p84 further providing evidence for the role of p101 in stimulation of PI3Kγ downstream of GPCRs. There is also evidence that the p110γ/p101 complex is preferentially activated by Rab8a downstream of toll-like receptors (TLR) through an unknown mechanism (Fig. 2.) (Luo et al., 2018, 2014). Given the restricted expression profile of p101, there is limited evidence of its involvement in disease. The PIK3R5 locus has been reported to be a site of retroviral insertion in T-cell lymphomas where its overexpression leads to enhanced survival of T-cells (Johnson et al., 2007). Knockdown of p101 in breast cancer and epithelial carcinoma cell lines reduced tumor growth and metastasis (Brazzatti et al., 2012). There is also evidence 5

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that PIK3R5 could have a role in brain development with missense mutations found in an autosomal recessive disease, Ataxia with oculomotor apraxia Type 2 (Tassan et al., 2012). 3.2. p84/p87 p84 (encoded by PIK3R6) was first identified in the mouse genome by sequence similarity to p101, on chromosome 11 just downstream of PIK3R5 (Suire et al., 2005). The p84 regulatory subunit is considered to be a part of a constitutively expressed form of PI3Kγ with high levels of expression in leukocytes, endothelial cells, and the heart (Shymanets et al., 2013). HDX-MS experiments indicated that the primary interface of p84 on p110γ is the C2-helical linker and helical domain (Walser et al., 2013). The p84 subunit still facilitates stimulation by GPCRs, but to a much lower extent than p101 (Fig. 2.) (Kurig et al., 2009). Studies in HEK cells expressing p110γ/p84 showed that Ras is necessary for complete activation of the complex by fMLP (Kurig et al., 2009). Macrophages require p84 for proper adhesion when stimulated by agonists of RTKs such as IL-1β, IL-6, CSF-1, VEGF-A, and TNFα. This is thought to happen through the activation of Ras by RTKs and subsequent activation of p110γ/p84 (Fig. 2.) (Schmid et al., 2011). In neutrophils, p84 has been shown to mediate reactive oxide production in response to fMLP, C5a, and LTB4 (Deladeriere et al., 2015). Mast cells require p84 for antigen and IgE induced degranulation mediated by adenosine, a GPCR agonist (Bohnacker et al., 2009). Interestingly, it was later found that GPCRs do not stimulate a considerable portion of this degranulation response. Instead, the influx of calcium ions and the subsequent activation of PKCβ has been shown to stimulate p110γ (Fig. 2.). PKCβ phosphorylates p110γ on S582, and this is thought to displace the p84 from the complex activating p110γ by a mechanism that is not entirely clear (Walser et al., 2013). In cardiomyocytes, p84 has been shown to mediate contractility downstream of the β-adrenergic receptor (βAR). This is reported to happen through binding of p84 to protein kinase A which phosphorylates T1024 on p110γ. This inhibitory modification subsequently reduces p110γ activity which serves to downregulate the internalization of β-AR (Perino et al., 2011). p110γ/p84 has also been proposed to control PKA activation through an interaction with phosphodiesterase 3B (PDE3B) which lowers cyclic AMP levels in cardiac muscle cells (Wilson et al., 2011). p84 knockout mice subjected to transverse aortic constriction exhibited higher rates of cardiac failure and cardiac function improved upon inhibition of PI3Kγ (Perino et al., 2011). 4. Conclusions The PI3K family of enzymes are essential mediators in how multiple cells and tissues respond to external signals. Critical to the regulation of class I PI3Ks is their adaptor proteins. These proteins have been found to play myriad regulatory roles, and disruption of this regulation is frequently found in multiple human diseases. Multiple PI3K inhibitors have now been approved in the clinic, with many additional clinical trials ongoing for a plethora of human diseases. However, there are still many unanswered questions that remain in the study of PI3K regulation. Defining the rules of engagement for both the formation of PI3K complexes, as well as how specificity in activation is achieved, is an important objective. It is also essential to define the molecular mechanisms that control enzyme activity, as more and more mutations are being found in both catalytic and regulatory subunits. Declaration of competing interest The authors declare that they have no conflict of interest with the publication of this manuscript. Acknowledgements J.E.B. would like to acknowledge funding from the Canadian Institutes of Health Research (New Investigator award and an Open Operating grant CRN-142393), the Cancer Research Society (Operating grant CRS-22641 and 24368), the Natural Sciences and Engineering Research Council of Canada (Discovery Grant NSERC-05218), and the Michael Smith Foundation for Health Research (MSFHR Scholar award 17686). References Angulo, I., Vadas, O., Garçon, F., Banham-Hall, E., Plagnol, V., Leahy, T.R., Baxendale, H., Coulter, T., Curtis, J., Wu, C., Blake-Palmer, K., Perisic, O., Smyth, D., Maes, M., Fiddler, C., Juss, J., Cilliers, D., Markelj, G., Chandra, A., Farmer, G., Kielkowska, A., Clark, J., Kracker, S., Debré, M., Picard, C., Pellier, I., Jabado, N., Morris, J.A., Barcenas-Morales, G., Fischer, A., Stephens, L., Hawkins, P., Barrett, J.C., Abinun, M., Clatworthy, M., Durandy, A., Doffinger, R., Chilvers, E.R., Cant, A.J., Kumararatne, D., Okkenhaug, K., Williams, R.L., Condliffe, A., Nejentsev, S., 2013. Phosphoinositide 3-kinase δ gene mutation predisposes to respiratory infection and airway damage. Science 342, 866–871. https://doi.org/10.1126/science.1243292. Backer, J.M., 2010. The regulation of class IA PI 3-kinases by inter-subunit interactions. Curr. Top. Microbiol. Immunol. 346, 87–114. https://doi.org/10.1007/82_ 2010_52. Balla, T., 2013. Phosphoinositides: tiny lipids with giant impact on cell regulation. Physiol. Rev. 93, 1019–1137. https://doi.org/10.1152/physrev.00028.2012. Bertacchini, J., Frasson, C., Chiarini, F., D'Avella, D., Accordi, B., Anselmi, L., Barozzi, P., Forghieri, F., Luppi, M., Martelli, A.M., Basso, G., Najmaldin, S., Khosravi, A., Rahim, F., Marmiroli, S., 2018. Dual inhibition of PI3K/mTOR signaling in chemoresistant AML primary cells. Adv. Biol. Regul. 68, 2–9. https://doi.org/10.1016/ j.jbior.2018.03.001. Bilanges, B., Posor, Y., Vanhaesebroeck, B., 2019. PI3K isoforms in cell signalling and vesicle trafficking. Nat. Rev. Mol. Cell Biol. 10, 6742. https://doi.org/10.1038/ s41580-019-0129-z. Bohnacker, T., Marone, R., Collmann, E., Calvez, R., Hirsch, E., Wymann, M., 2009. PI3Kgamma adaptor subunits define coupling to degranulation and cell motility by distinct PtdIns(3,4,5)P3 pools in mast cells. Sci. Signal. 2https://doi.org/10.1126/scisignal.2000259. ra27. Bravo García-Morato, M., García-Miñaúr, S., Molina Garicano, J., Santos Simarro, F., Del Pino Molina, L., López-Granados, E., Ferreira Cerdán, A., Rodríguez Pena, R.,

6

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M.K. Rathinaswamy and J.E. Burke

2017. Mutations in PIK3R1 can lead to APDS2, SHORT syndrome or a combination of the two. Clin. Immunol. 179, 77–80. https://doi.org/10.1016/j.clim.2017. 03.004. Brazzatti, J.A., Klingler-Hoffmann, M., Haylock-Jacobs, S., Harata-Lee, Y., Niu, M., Higgins, M.D., Kochetkova, M., Hoffmann, P., McColl, S.R., 2012. Differential roles for the p101 and p84 regulatory subunits of PI3Kγ in tumor growth and metastasis. Oncogene 31, 2350–2361. https://doi.org/10.1038/onc.2011.414. Buckles, T.C., Ziemba, B.P., Masson, G.R., Williams, R.L., Falke, J.J., 2017. Single-molecule study reveals how receptor and Ras synergistically activate PI3Kα and PIP3 signaling. Biophys. J. 113, 2396–2405. https://doi.org/10.1016/j.bpj.2017.09.018. Burke, J.E., 2018. Structural basis for regulation of phosphoinositide kinases and their involvement in human disease. Mol. Cell 71, 653–673. https://doi.org/10.1016/ j.molcel.2018.08.005. Burke, J.E., Perisic, O., Masson, G.R., Vadas, O., Williams, R.L., 2012. Oncogenic mutations mimic and enhance dynamic events in the natural activation of phosphoinositide 3-kinase p110α (PIK3CA). Proc. Natl. Acad. Sci. U.S.A. 109, 15259–15264. https://doi.org/10.1073/pnas.1205508109. Burke, J.E., Vadas, O., Berndt, A., Finegan, T., Perisic, O., Williams, R.L., 2011. Dynamics of the phosphoinositide 3-kinase p110δ interaction with p85α and membranes reveals aspects of regulation distinct from p110α. Structure 19, 1127–1137. https://doi.org/10.1016/j.str.2011.06.003. Burke, J.E., Williams, R.L., 2015. Synergy in activating class I PI3Ks. Trends Biochem. Sci. 40, 88–100. https://doi.org/10.1016/j.tibs.2014.12.003. Burke, J.E., Williams, R.L., 2013. Dynamic steps in receptor tyrosine kinase mediated activation of class IA phosphoinositide 3-kinases (PI3K) captured by H/D exchange (HDX-MS). Adv. Biol. Regul. 53, 97–110. https://doi.org/10.1016/j.jbior.2012.09.005. Cariaga-Martínez, A.E., Cortés, I., García, E., Pérez-García, V., Pajares, M.J., Idoate, M.A., Redondo-Muñoz, J., Antón, I.M., Carrera, A.C., 2014. Phosphoinositide 3kinase p85beta regulates invadopodium formation. Biol. Open 3, 924–936. https://doi.org/10.1242/bio.20148185. Carpenter, C.L., Auger, K.R., Chanudhuri, M., Yoakim, M., Schaffhausen, B., Shoelson, S., Cantley, L.C., 1993. Phosphoinositide 3-kinase is activated by phosphopeptides that bind to the SH2 domains of the 85-kDa subunit. J. Biol. Chem. 268, 9478–9483. Cheung, L., Hennessy, B., Li, J., Yu, S., Myers, A., Djordjevic, B., Lu, Y., Stemke-Hale, K., Zhang, F., Ju, Z., Cantley, L., Scherer, S., Liang, H., Lu, K., Broaddus, R., Mills, G., 2011. High frequency of PIK3R1 and PIK3R2 mutations in endometrial cancer elucidates a novel mechanism for regulation of PTEN protein stability. Cancer Discov. 1, 170–185. https://doi.org/10.1158/2159-8290.CD-11-0039. Cheung, L.W.T., Walkiewicz, K.W., Besong, T.M.D., Guo, H., Hawke, D.H., Arold, S.T., Mills, G.B., 2015. Regulation of the PI3K pathway through a p85α monomerhomodimer equilibrium. Elife 4, e06866. https://doi.org/10.7554/eLife.06866. Comb, W.C., Hutti, J.E., Cogswell, P., Cantley, L.C., Baldwin, A.S., 2012. p85α SH2 domain phosphorylation by IKK promotes feedback inhibition of PI3K and Akt in response to cellular starvation. Mol. Cell 45, 719–730. https://doi.org/10.1016/j.molcel.2012.01.010. Cortés, I., Sánchez-Ruíz, J., Zuluaga, S., Calvanese, V., Marqués, M., Hernández, C., Rivera, T., Kremer, L., González-García, A., Carrera, A.C., 2012. p85β phosphoinositide 3-kinase subunit regulates tumor progression. Proc. Natl. Acad. Sci. U.S.A. 109, 11318–11323. https://doi.org/10.1073/pnas.1118138109. Cuevas, B.D., Lu, Y., Mao, M., Zhang, J., LaPushin, R., Siminovitch, K., Mills, G.B., 2001. Tyrosine phosphorylation of p85 relieves its inhibitory activity on phosphatidylinositol 3-kinase. J. Biol. Chem. 276, 27455–27461. https://doi.org/10.1074/jbc.M100556200. Dbouk, H.A., Pang, H., Fiser, A., Backer, J.M., 2010. A biochemical mechanism for the oncogenic potential of the p110{beta} catalytic subunit of phosphoinositide 3kinase. Proc. Natl. Acad. Sci. U.S.A. 107, 19897–19902. https://doi.org/10.1073/pnas.1008739107/-/DCSupplemental. Deau, M.-C., Heurtier, L., Frange, P., Suarez, F., Bole-Feysot, C., Nitschke, P., Cavazzana, M., Picard, C., Durandy, A., Fischer, A., Kracker, S., 2014. A human immunodeficiency caused by mutations in the PIK3R1 gene. J. Clin. Investig. 124, 3923–3928. https://doi.org/10.1172/JCI75746. Deladeriere, A., Gambardella, L., Pan, D., Anderson, K.E., Hawkins, P.T., Stephens, L.R., 2015. The regulatory subunits of PI3Kγ control distinct neutrophil responses. Sci. Signal. 8https://doi.org/10.1126/scisignal.2005564. ra8. Dhand, R., Hiles, I., Panayotou, G., Roche, S., Fry, M.J., Gout, I., Totty, N.F., Truong, O., Vicendo, P., Yonezawa, K., 1994. PI 3-kinase is a dual specificity enzyme: autoregulation by an intrinsic protein-serine kinase activity. EMBO J. 13, 522–533. Dornan, G.L., Siempelkamp, B.D., Jenkins, M.L., Vadas, O., Lucas, C.L., Burke, J.E., 2017. Conformational disruption of PI3Kδ regulation by immunodeficiency mutations in PIK3CD and PIK3R1. Proc. Natl. Acad. Sci. U.S.A. 114, 1982–1987. https://doi.org/10.1073/pnas.1617244114. Eickholt, B.J., Ahmed, A.I., Davies, M., Papakonstanti, E.A., Pearce, W., Starkey, M.L., Bilancio, A., Need, A.C., Smith, A.J.H., Hall, S.M., Hamers, F.P., Giese, K.P., Bradbury, E.J., Vanhaesebroeck, B., 2007. Control of axonal growth and regeneration of sensory neurons by the p110delta PI 3-kinase. PLoS One 2, e869. https:// doi.org/10.1371/journal.pone.0000869. Fang, D., Wang, H.Y., Fang, N., Altman, Y., Elly, C., Liu, Y.C., 2001. Cbl-b, a RING-type E3 ubiquitin ligase, targets phosphatidylinositol 3-kinase for ubiquitination in T cells. J. Biol. Chem. 276, 4872–4878. https://doi.org/10.1074/jbc.M008901200. Fritsch, R., de Krijger, I., Fritsch, K., George, R., Reason, B., Kumar, M.S., Diefenbacher, M., Stamp, G., Downward, J., 2013. RAS and RHO families of GTPases directly regulate distinct phosphoinositide 3-kinase isoforms. Cell 153, 1050–1063. https://doi.org/10.1016/j.cell.2013.04.031. Fruman, D.A., Chiu, H., Hopkins, B.D., Bagrodia, S., Cantley, L.C., Abraham, R.T., 2017. The PI3K pathway in human disease. Cell 170, 605–635. https://doi.org/10. 1016/j.cell.2017.07.029. Fruman, D.A., Mauvais-Jarvis, F., Pollard, D.A., Yballe, C.M., Brazil, D., Bronson, R.T., Kahn, C.R., Cantley, L.C., 2000. Hypoglycaemia, liver necrosis and perinatal death in mice lacking all isoforms of phosphoinositide 3-kinase p85 alpha. Nat. Genet. 26, 379–382. https://doi.org/10.1038/81715. Fruman, D.A., Snapper, S.B., Yballe, C.M., Davidson, L., Yu, J.Y., Alt, F.W., Cantley, L.C., 1999. Impaired B cell development and proliferation in absence of phosphoinositide 3-kinase p85alpha. Science 283, 393–397. Hanker, A.B., Kaklamani, V., Arteaga, C.L., 2019. Challenges for the clinical development of PI3K inhibitors: strategies to improve their impact in solid tumors. Cancer Discov. 9, 482–491. https://doi.org/10.1158/2159-8290.CD-18-1175. Hermida, M.A., Dinesh Kumar, J., Leslie, N.R., 2017. GSK3 and its interactions with the PI3K/AKT/mTOR signalling network. Adv. Biol. Regul. 65, 5–15. https://doi. org/10.1016/j.jbior.2017.06.003. Hirsch, E., Katanaev, V.L., Garlanda, C., Azzolino, O., Pirola, L., Silengo, L., Sozzani, S., Mantovani, A., Altruda, F., Wymann, M.P., 2000. Central role for G proteincoupled phosphoinositide 3-kinase gamma in inflammation. Science 287, 1049–1053. Huang-Doran, I., Tomlinson, P., Payne, F., Gast, A., Sleigh, A., Bottomley, W., Harris, J., Daly, A., Rocha, N., Rudge, S., Clark, J., Kwok, A., Romeo, S., McCann, E., Müksch, B., Dattani, M., Zucchini, S., Wakelam, M., Foukas, L.C., Savage, D.B., Murphy, R., O'Rahilly, S., Barroso, I., Semple, R.K., 2016. Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations. JCI Insight 1, e88766. https://doi.org/10.1172/jci.insight.88766. Inukai, K., Anai, M., Van Breda, E., Hosaka, T., Katagiri, H., Funaki, M., Fukushima, Y., Ogihara, T., Yazaki, Y., Kikuchi, Oka, Y., Asano, T., 1996. A novel 55-kDa regulatory subunit for phosphatidylinositol 3-kinase structurally similar to p55PIK Is generated by alternative splicing of the p85alpha gene. J. Biol. Chem. 271, 5317–5320. https://doi.org/10.1074/jbc.271.10.5317. Ito, Y., Hart, J.R., Ueno, L., Vogt, P.K., 2014. Oncogenic activity of the regulatory subunit p85β of phosphatidylinositol 3-kinase (PI3K). Proc. Natl. Acad. Sci. U.S.A. https://doi.org/10.1073/pnas.1420281111. Jaiswal, B.S., Janakiraman, V., Kljavin, N.M., Chaudhuri, S., Stern, H.M., Wang, W., Kan, Z., Dbouk, H.A., Peters, B.A., Waring, P., Vega, Dela T., Kenski, D.M., Bowman, K.K., Lorenzo, M., Li, H., Wu, J., Modrusan, Z., Stinson, J., Eby, M., Yue, P., Kaminker, J.S., de Sauvage, F.J., Backer, J.M., Seshagiri, S., 2009. Somatic mutations in p85a promote tumorigenesis through class IA PI3K activation. Cancer Cell 16, 463–474. https://doi.org/10.1016/j.ccr.2009.10.016. Jia, S., Liu, Z., Zhang, S., Liu, P., Zhang, L., Lee, S., Zhang, J., Signoretti, S., Loda, M., Roberts, T., Zhao, J., 2008. Essential roles of PI(3)K-p110beta in cell growth, metabolism and tumorigenesis. Nature 454, 776–779. https://doi.org/10.1038/nature07091. Johnson, C., Marriott, S., Levy, L., 2007. Overexpression of p101 activates PI3Kgamma signaling in T cells and contributes to cell survival. Oncogene 26, 7049–7057. https://doi.org/10.1038/sj.onc.1210504. Kaneda, M.M., Messer, K.S., Ralainirina, N., Li, H., Leem, C.J., Gorjestani, S., Woo, G., Nguyen, A.V., Figueiredo, C.C., Foubert, P., Schmid, M.C., Pink, M., Winkler, D.G., Rausch, M., Palombella, V.J., Kutok, J., McGovern, K., Frazer, K.A., Wu, X., Karin, M., Sasik, R., Cohen, E.E.W., Varner, J.A., 2016. PI3Kγ is a molecular switch that controls immune suppression. Nature 539, 437–442. https://doi.org/10.1038/nature19834. Klippel, A., Escobedo, J.A., Fantl, W.J., Williams, L.T., 1992. The C-terminal SH2 domain of p85 accounts for the high affinity and specificity of the binding of phosphatidylinositol 3-kinase to phosphorylated platelet-derived growth factor beta receptor. Mol. Cell. Biol. 12, 1451–1459.

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Advances in Biological Regulation xxx (xxxx) xxxx

M.K. Rathinaswamy and J.E. Burke

Kuchay, S., Duan, S., Schenkein, E., Peschiaroli, A., Saraf, A., Florens, L., Washburn, M.P., Pagano, M., 2013. FBXL2- and PTPL1-mediated degradation of p110-free p85β regulatory subunit controls the PI(3)K signalling cascade. Nat. Cell Biol. 15, 472–480. https://doi.org/10.1038/ncb2731. Kurig, B., Shymanets, A., Bohnacker, T., Prajwal, Brock, C., Ahmadian, M.R., Schaefer, M., Gohla, A., Harteneck, C., Wymann, M.P., Jeanclos, E., Nürnberg, B., 2009. Ras is an indispensable coregulator of the class IB phosphoinositide 3-kinase p87/p110gamma. Proc. Natl. Acad. Sci. U.S.A. 106, 20312–20317. https://doi.org/ 10.1073/pnas.0905506106. Kurosu, H., Maehama, T., Okada, T., Yamamoto, T., Hoshino, S., Fukui, Y., Ui, M., Hazeki, O., Katada, T., 1997. Heterodimeric phosphoinositide 3-kinase consisting of p85 and p110beta is synergistically activated by the betagamma subunits of G proteins and phosphotyrosyl peptide. J. Biol. Chem. 272, 24252–24256. Lee, J.Y., Chiu, Y.-H., Asara, J., Cantley, L.C., 2011. Inhibition of PI3K binding to activators by serine phosphorylation of PI3K regulatory subunit p85alpha Src homology-2 domains. Proc. Natl. Acad. Sci. U.S.A. 108, 14157–14162. https://doi.org/10.1073/pnas.1107747108. Lindhurst, M.J., Parker, V.E.R., Payne, F., Sapp, J.C., Rudge, S., Harris, J., Witkowski, A.M., Zhang, Q., Groeneveld, M.P., Scott, C.E., Daly, A., Huson, S.M., Tosi, L.L., Cunningham, M.L., Darling, T.N., Geer, J., Gucev, Z., Sutton, V.R., Tziotzios, C., Dixon, A.K., Helliwell, T., O'Rahilly, S., Savage, D.B., Wakelam, M.J.O., Barroso, I., Biesecker, L.G., Semple, R.K., 2012. Mosaic overgrowth with fibroadipose hyperplasia is caused by somatic activating mutations in PIK3CA. Nat. Genet. 44, 928–933. https://doi.org/10.1038/ng.2332. Lucas, C.L., Chandra, A., Nejentsev, S., Condliffe, A.M., Okkenhaug, K., 2016. PI3Kδ and primary immunodeficiencies. Nat. Rev. Immunol. 16, 702–714. https://doi. org/10.1038/nri.2016.93. Lucas, C.L., Kuehn, H.S., Zhao, F., Niemela, J.E., Deenick, E.K., Palendira, U., Avery, D.T., Moens, L., Cannons, J.L., Biancalana, M., Stoddard, J., Ouyang, W., Frucht, D.M., Rao, V.K., Atkinson, T.P., Agharahimi, A., Hussey, A.A., Folio, L.R., Olivier, K.N., Fleisher, T.A., Pittaluga, S., Holland, S.M., Cohen, J.I., Oliveira, J.B., Tangye, S.G., Schwartzberg, P.L., Lenardo, M.J., Uzel, G., 2014a. Dominant-activating germline mutations in the gene encoding the PI(3)K catalytic subunit p110δ result in T cell senescence and human immunodeficiency. Nat. Immunol. 15, 88–97. https://doi.org/10.1038/ni.2771. Lucas, C.L., Zhang, Y., Venida, A., Wang, Y., Hughes, J., McElwee, J., Butrick, M., Matthews, H., Price, S., Biancalana, M., Wang, X., Richards, M., Pozos, T., Barlan, I., Ozen, A., Rao, V.K., Su, H.C., Lenardo, M.J., 2014b. Heterozygous splice mutation in PIK3R1 causes human immunodeficiency with lymphoproliferation due to dominant activation of PI3K. J. Exp. Med. 211, 2537–2547. https://doi.org/10.1084/jem.20141759. Lučić, I., Rathinaswamy, M.K., Truebestein, L., Hamelin, D.J., Burke, J.E., Leonard, T.A., 2018. Conformational sampling of membranes by Akt controls its activation and inactivation. Proc. Natl. Acad. Sci. U.S.A. 115, E3940–E3949. https://doi.org/10.1073/pnas.1716109115. Luo, L., Wall, A.A., Tong, S.J., Hung, Y., Xiao, Z., Tarique, A.A., Sly, P.D., Fantino, E., Marzolo, M.-P., Stow, J.L., 2018. TLR crosstalk activates LRP1 to recruit Rab8a and PI3Kγ for suppression of inflammatory responses. Cell Rep. 24, 3033–3044. https://doi.org/10.1016/j.celrep.2018.08.028. Luo, L., Wall, A.A., Yeo, J.C., Condon, N.D., Norwood, S.J., Schoenwaelder, S., Chen, K.W., Jackson, S., Jenkins, B.J., Hartland, E.L., Schroder, K., Collins, B.M., Sweet, M.J., Stow, J.L., 2014. Rab8a interacts directly with PI3Kγ to modulate TLR4-driven PI3K and mTOR signalling. Nat. Commun. 5, 4407. https://doi.org/10.1038/ ncomms5407. Madsen, R.R., Vanhaesenbroeck, B., Semple, R.K., Cancer-Associated PIK3CA Mutations in Overgrowth Disorders, 2018. Cancer-associated PIK3CA mutations in overgrowth disorders. Trends Mol. Med. 24, 856–870. https://doi.org/10.1016/j.molmed.2018.08.003. Mandelker, D., Gabelli, S.B., Schmidt-Kittler, O., Zhu, J., Cheong, I., Huang, C.-H., Kinzler, K.W., Vogelstein, B., Amzel, L.M., 2009. A frequent kinase domain mutation that changes the interaction between PI3Kalpha and the membrane. Proc. Natl. Acad. Sci. U.S.A. 106, 16996–17001. https://doi.org/10.1073/pnas.0908444106. Miled, N., Yan, Y., Hon, W.-C., Perisic, O., Zvelebil, M., Inbar, Y., Schneidman-Duhovny, D., Wolfson, H.J., Backer, J.M., Williams, R.L., 2007. Mechanism of two classes of cancer mutations in the phosphoinositide 3-kinase catalytic subunit. Science 317, 239–242. https://doi.org/10.1126/science.1135394. Okkenhaug, K., 2013. Signaling by the phosphoinositide 3-kinase family in immune cells. Annu. Rev. Immunol. 31, 675–704. https://doi.org/10.1146/annurevimmunol-032712-095946. Pacold, M.E., Suire, S., Perisic, O., Lara-Gonzalez, S., Davis, C.T., Walker, E.H., Hawkins, P.T., Stephens, L., Eccleston, J.F., Williams, R.L., 2000. Crystal structure and functional analysis of Ras binding to its effector phosphoinositide 3-kinase gamma. Cell 103, 931–943. Patrucco, E., Notte, A., Barberis, L., Selvetella, G., Maffei, A., Brancaccio, M., Marengo, S., Russo, G., Azzolino, O., Rybalkin, S.D., Silengo, L., Altruda, F., Wetzker, R., Wymann, M.P., Lembo, G., Hirsch, E., 2004. PI3Kgamma modulates the cardiac response to chronic pressure overload by distinct kinase-dependent and -independent effects. Cell 118, 375–387. https://doi.org/10.1016/j.cell.2004.07.017. Perino, A., Ghigo, A., Ferrero, E., Morello, F., Santulli, G., Baillie, G.S., Damilano, F., Dunlop, A.J., Pawson, C., Walser, R., Levi, R., Altruda, F., Silengo, L., Langeberg, L.K., Neubauer, G., Heymans, S., Lembo, G., Wymann, M.P., Wetzker, R., Houslay, M.D., Iaccarino, G., Scott, J.D., Hirsch, E., 2011. Integrating cardiac PIP(3) and cAMP signaling through a PKA anchoring function of p110gamma. Mol. Cell 42, 84–95. https://doi.org/10.1016/j.molcel.2011.01.030. Philippon, H., Brochier-Armanet, C., Perrière, G., 2015. Evolutionary history of phosphatidylinositol- 3-kinases: ancestral origin in eukaryotes and complex duplication patterns. BMC Evol. Biol. 15https://doi.org/10.1186/s12862-015-0498-7. 226–16. Philp, A.J., Campbell, I.G., Leet, C., Vincan, E., Rockman, S.P., Whitehead, R.H., Thomas, R.J., Phillips, W.A., 2001. The phosphatidylinositol 3'-kinase p85alpha gene is an oncogene in human ovarian and colon tumors. Cancer Res. 61, 7426–7429. Ricciardi, M.R., Mirabilii, S., Licchetta, R., Piedimonte, M., Tafuri, A., 2017. Targeting the Akt, GSK-3, Bcl-2 axis in acute myeloid leukemia. Adv. Biol. Regul. 65, 36–58. https://doi.org/10.1016/j.jbior.2017.05.002. Rivière, J.-B., Mirzaa, G.M., O'Roak, B.J., Beddaoui, M., Alcantara, D., Conway, R.L., St-Onge, J., Schwartzentruber, J.A., Gripp, K.W., Nikkel, S.M., Worthylake, T., Sullivan, C.T., Ward, T.R., Butler, H.E., Kramer, N.A., Albrecht, B., Armour, C.M., Armstrong, L., Caluseriu, O., Cytrynbaum, C., Drolet, B.A., Innes, A.M., Lauzon, J.L., Lin, A.E., Mancini, G.M.S., Meschino, W.S., Reggin, J.D., Saggar, A.K., Lerman-Sagie, T., Uyanik, G., Weksberg, R., Zirn, B., Beaulieu, C.L., Finding of Rare Disease Genes (FORGE) Canada Consortium,Majewski, J., Bulman, D.E., O'Driscoll, M., Shendure, J., Graham, J.M., Boycott, K.M., Dobyns, W.B., 2012. De novo germline and postzygotic mutations in AKT3, PIK3R2 and PIK3CA cause a spectrum of related megalencephaly syndromes. Nat. Genet. 44, 934–940. https://doi. org/10.1038/ng.2331. Rodriguez-Viciana, P., Warne, P.H., Dhand, R., Vanhaesebroeck, B., Gout, I., Fry, M.J., Waterfield, M.D., Downward, J., 1994. Phosphatidylinositol-3-OH kinase as a direct target of Ras. Nature 370, 527–532. https://doi.org/10.1038/370527a0. Samuels, Y., Wang, Z., Bardelli, A., Silliman, N., Ptak, J., Szabo, S., Yan, H., Gazdar, A., Powell, S., Riggins, G., Willson, J., Markowitz, S., Kinzler, K., Vogelstein, B., Velculescu, V., 2004. High frequency of mutations of the PIK3CA gene in human cancers. Science 304, 554. https://doi.org/10.1126/science.1096502. Schmid, M.C., Avraamides, C.J., Dippold, H.C., Franco, I., Foubert, P., Ellies, L.G., Acevedo, L.M., Manglicmot, J.R.E., Song, X., Wrasidlo, W., Blair, S.L., Ginsberg, M.H., Cheresh, D.A., Hirsch, E., Field, S.J., Varner, J.A., 2011. Receptor tyrosine kinases and TLR/IL1Rs unexpectedly activate myeloid cell PI3kγ, a single convergent point promoting tumor inflammation and progression. Cancer Cell 19, 715–727. https://doi.org/10.1016/j.ccr.2011.04.016. Shepherd, P.R., Withers, D.J., Siddle, K., 1998. Phosphoinositide 3-kinase: the key switch mechanism in insulin signalling. Biochem. J. 333 (Pt 3), 471–490. https:// doi.org/10.1042/bj3330471. Shymanets, A., Prajwal, P., Bucher, K., Beer-Hammer, S., Harteneck, C., Nürnberg, B., 2013. p87 and p101 subunits are distinct regulators determining class IB PI3K specificity. J. Biol. Chem. https://doi.org/10.1074/jbc.M113.508234. Siempelkamp, B.D., Rathinaswamy, M.K., Jenkins, M.L., Burke, J.E., 2017. Molecular mechanism of activation of class IA phosphoinositide 3-kinases (PI3Ks) by membrane-localized HRas. J. Biol. Chem. 292, 12256–12266. https://doi.org/10.1074/jbc.M117.789263. Songyang, Z., Shoelson, S.E., Chaudhuri, M., Gish, G., Pawson, T., Haser, W.G., King, F., Roberts, T., Ratnofsky, S., Lechleider, R.J., 1993. SH2 domains recognize specific phosphopeptide sequences. Cell 72, 767–778. Stephens, L., Smrcka, A., Cooke, F.T., Jackson, T.R., Sternweis, P.C., Hawkins, P.T., 1994. A novel phosphoinositide 3 kinase activity in myeloid-derived cells is activated by G protein beta gamma subunits. Cell 77, 83–93. https://doi.org/10.1016/0092-8674(94)90237-2. Stephens, L.R., Eguinoa, A., Erdjument-Bromage, H., Lui, M., Cooke, F., Coadwell, J., Smrcka, A.S., Thelen, M., Cadwallader, K., Tempst, P., Hawkins, P.T., 1997. The G beta gamma sensitivity of a PI3K is dependent upon a tightly associated adaptor, p101. Cell 89, 105–114. https://doi.org/10.1016/s0092-8674(00)80187-7. Suire, S., Coadwell, J., Ferguson, G.J., Davidson, K., Hawkins, P., Stephens, L., 2005. p84, a new Gbetagamma-activated regulatory subunit of the type IB phosphoinositide 3-kinase p110gamma. Curr. Biol. 15, 566–570. https://doi.org/10.1016/j.cub.2005.02.020. Tassan, Al N., Khalil, D., Shinwari, J., Sharif Al, L., Bavi, P., Abduljaleel, Z., Abu Dhaim, N., Magrashi, A., Bobis, S., Ahmed, H., Alahmed, S., Bohlega, S., 2012. A

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M.K. Rathinaswamy and J.E. Burke

missense mutation in PIK3R5 gene in a family with ataxia and oculomotor apraxia. Hum. Mutat. 33, 351–354. https://doi.org/10.1002/humu.21650. Thauvin-Robinet, C., Auclair, M., Duplomb, L., Caron-Debarle, M., Avila, M., St-Onge, J., Le Merrer, M., Le Luyer, B., Héron, D., Mathieu-Dramard, M., Bitoun, P., Petit, J.-M., Odent, S., Amiel, J., Picot, D., Carmignac, V., Thevenon, J., Callier, P., Laville, M., Reznik, Y., Fagour, C., Nunes, M.-L., Capeau, J., Lascols, O., Huet, F., Faivre, L., Vigouroux, C., Rivière, J.-B., 2013. PIK3R1 mutations cause syndromic insulin resistance with lipoatrophy. Am. J. Hum. Genet. 93, 141–149. https:// doi.org/10.1016/j.ajhg.2013.05.019. Thorpe, L.M., Spangle, J.M., Ohlson, C.E., Cheng, H., Roberts, T.M., Cantley, L.C., Zhao, J.J., 2017. PI3K-p110α mediates the oncogenic activity induced by loss of the novel tumor suppressor PI3K-p85α. Proc. Natl. Acad. Sci. U.S.A. 114, 7095–7100. https://doi.org/10.1073/pnas.1704706114. Tsolakos, N., Durrant, T.N., Chessa, T., Suire, S.M., Oxley, D., Kulkarni, S., Downward, J., Perisic, O., Williams, R.L., Stephens, L., Hawkins, P.T., 2018. Quantitation of class IA PI3Ks in mice reveals p110-free-p85s and isoform-selective subunit associations and recruitment to receptors. Proc. Natl. Acad. Sci. U.S.A. 115, 12176–12181. https://doi.org/10.1073/pnas.1803446115. Ueki, K., Brachmann, S.M., Vicent, D., Watt, J.M., Kahn, C.R., Cantley, L.C., 2002. Increased insulin sensitivity in mice lacking p85beta subunit of phosphoinositide 3kinase. Proc. Natl. Acad. Sci. U.S.A. 99, 419–424. https://doi.org/10.1073/pnas.012581799. Urick, M.E., Rudd, M.L., Godwin, A.K., Sgroi, D., Merino, M., Bell, D.W., 2011. PIK3R1 (p85α) is somatically mutated at high frequency in primary endometrial cancer. Cancer Res. 71, 4061–4067. https://doi.org/10.1158/0008-5472.CAN-11-0549. Vadas, O., Burke, J.E., Zhang, X., Berndt, A., Williams, R.L., 2011. Structural basis for activation and inhibition of class I phosphoinositide 3-kinases. Sci. Signal. 4, 1–13. https://doi.org/10.1126/scisignal.2002165. Vadas, O., Dbouk, H.A., Shymanets, A., Perisic, O., Burke, J.E., Abi Saab, W.F., Khalil, B.D., Harteneck, C., Bresnick, A.R., Nürnberg, B., Backer, J.M., Williams, R.L., 2013. Molecular determinants of PI3Kγ-mediated activation downstream of G-protein-coupled receptors (GPCRs). Proc. Natl. Acad. Sci. U.S.A. 110, 18862–18867. https://doi.org/10.1073/pnas.1304801110. Vanhaesebroeck, B., Guillermet-Guibert, J., Graupera, M., Bilanges, B., 2010. The emerging mechanisms of isoform-specific PI3K signalling. Nat. Rev. Mol. Cell Biol. 11, 329–341. https://doi.org/10.1038/nrm2882. Walker, E.H., Perisic, O., Ried, C., Stephens, L., Williams, R.L., 1999. Structural insights into phosphoinositide 3-kinase catalysis and signalling. Nature 402, 313–320. https://doi.org/10.1038/46319. Walser, R., Burke, J.E., Gogvadze, E., Bohnacker, T., Zhang, X., Hess, D., Küenzi, P., Leitges, M., Hirsch, E., Williams, R.L., Laffargue, M., Wymann, M.P., 2013. PKCβ phosphorylates PI3Kγ to activate it and release it from GPCR control. PLoS Biol. 11, e1001587. https://doi.org/10.1371/journal.pbio.1001587. Willebrand von, M., Williams, S., Saxena, M., Gilman, J., Tailor, P., Jascur, T., Amarante-Mendes, G.P., Green, D.R., Mustelin, T., 1998. Modification of phosphatidylinositol 3-kinase SH2 domain binding properties by Abl- or Lck-mediated tyrosine phosphorylation at Tyr-688. J. Biol. Chem. 273, 3994–4000. https://doi.org/ 10.1074/jbc.273.7.3994. Wilson, L.S., Baillie, G.S., Pritchard, L.M., Umana, B., Terrin, A., Zaccolo, M., Houslay, M.D., Maurice, D.H., 2011. A phosphodiesterase 3B-based signaling complex integrates exchange protein activated by cAMP 1 and phosphatidylinositol 3-kinase signals in human arterial endothelial cells. J. Biol. Chem. 286, 16285–16296. https://doi.org/10.1074/jbc.M110.217026. Yu, J., Wjasow, C., Backer, J.M., 1998a. Regulation of the p85/p110alpha phosphatidylinositol 3'-kinase. Distinct roles for the n-terminal and c-terminal SH2 domains. J. Biol. Chem. 273, 30199–30203. Yu, J., Zhang, Y., McIlroy, J., Rordorf-Nikolic, T., Orr, G.A., Backer, J.M., 1998b. Regulation of the p85/p110 phosphatidylinositol 3'-kinase: stabilization and inhibition of the p110alpha catalytic subunit by the p85 regulatory subunit. Mol. Cell. Biol. 18, 1379–1387. Zhang, X., Vadas, O., Perisic, O., Anderson, K.E., Clark, J., Hawkins, P.T., Stephens, L.R., Williams, R.L., 2011. Structure of lipid kinase p110b/p85b elucidatesan unusual SH2-domain-mediated inhibitory mechanism. Mol. Cell 41, 567–578. https://doi.org/10.1016/j.molcel.2011.01.026.

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