- Email: [email protected]
Oxidative Stress and the Triangle of Death in Alzheimer Disease Brain: The Aberrant Crosstalk among Energy Metabolism, MTOR Signaling and Protein Homeostasis Revealed by Redox Proteomics
(AD). Interestingly, the efficacy of intranasal insulin (I-Ins) administration – which allows to directly transport insulin to the CNS – was proposed as an innovative therapeutic strategy to alleviate cognitive dysfunction in AD. However, significant gaps in our knowledge about the mechanisms underlying these beneficial outcomes still exist. We previously reported about the oxidativestress (OS) induced impairment of biliverdin reductase A (BVR-A) [a novel direct target of the insulin receptor (IR) kinase activity] as an early event contributing to b.i.r. in AD. Indeed, under normal conditions, once IR-activated BVR-A controls the activation of the insulin receptor substrate (IRS)-1, thus representing an upstream regulator of the insulin signaling cascade. Conversely, along the progression of AD pathology, the OS-induced inactivation of BVRA promotes the hyper-activation of the IR/IRS-1 axis, which finally lead to b.i.r.. Here we hypothesized that the I-Ins-associated beneficial effects on cognition would be mediated by the restoration of BVR-A activity. To this aim, we evaluated in vivo (i) changes of the insulin signaling cascade (ii) variations of total OS markers (PC, HNE, 3NT), (iii) changes of AD neuropathology markers e.g., Aβ and tau levels, in the hippocampus of 3xTg-AD and WT mice undergoing an early (4 months) or late (10 moths) intranasal insulin treatment (1 U/day, 3 times per week, for 2 months). Furthermore, changes of cognitive functions assessed through the morris water maze (MWM) and the novel object recognition (NOR) tasks, were evaluated. We found that I-Ins administration rescue the activation of BVR-A both in young and old 3xTg-AD mice. Improved BVR-A activity is associated with (i) reduced OS markers, (ii) a restoration of the insulin signaling cascade and (iii) a reduction of Tau pathology in the hippocampus. All these changes parallel an improved cognition. Interestingly, cell-based experiments confirmed the role of BVR-A by showing no beneficial effects of insulin when BVR-A is knocked-down.
doi: 10.1016/j.freeradbiomed.2016.10.412 372 Neuronal Deletion of Manganese Superoxide Dismutase Altered TCA Cycle Metabolism and Caused Severe Peripheral Nerve Demyelination in Mice Marcio Buffolo1, Shaobo Pei1, Karla Maria Pereira-Pires1, Janaina Paulini2, Luciana Jorge2, and Sihem Boudina1 1 University of Utah, Salt Lake City, USA, 2São Paulo Federal University, Brazil Oxidative stress and mitochondrial dysfunction have been increasingly recognized as contributing factors for the pathogenesis of various diseases, including neurodegenerative diseases. Manganese superoxide dismutase (MnSOD) is the sole mitochondrial matrix enzyme that converts dismutate superoxide to hydrogen peroxide. Previous studies investigating the role of MnSOD in the central nervous system have used mice lacking this enzyme in neuronal stem cells and showed perinatal lethality and severe growth retardation. However, the underlying mechanisms for the phenotype of brain-specific MnSOD knockout (BSOD) mice is not well understood. Here used BSOD mice on a C57B background and show that mitochondrial function was preserved in whole brain sections despite increased superoxide levels. We also demonstrated that BSOD mice fail to feed at about post-natal day 15 and develop severe diabetic ketoacidosis. Although the overall morphology of the central nervous system was not altered in BSOD mice, peripheral nerves ultrastructure was severely affected as
S158
evidenced by myelin delamination. Interestingly, metabolomic analysis of the sciatic nerves of BSOD mice showed reduced polyol pathway and increased glycerol levels. Furthermore, there was a massive accumulation of the oncometabolite 2-hydroxyglutarate both in whole brain homogenates and in sciatic nerves of BSOD mice. Taken together, these results indicate that MnSOD deletion in neuronal cells causes peripheral neuropathy in part via impairment of mitochondrial metabolism.
doi: 10.1016/j.freeradbiomed.2016.10.413 373 Oxidative Stress and the Triangle of Death in Alzheimer Disease Brain: The Aberrant Crosstalk among Energy Metabolism, MTOR Signaling and Protein Homeostasis Revealed by Redox Proteomics D. Allan Butterfield1, Eugenio Barone2, Marzia Perluigi2, and Fabio Di Domenico2 1 University of Kentucky, Lexington, USA, 2University of Rome La Sapienza, Italy Alzheimer disease (AD), a multifactorial neurodegenerative disorder that represents one of the most disabling conditions in the aged population, shares many features in common with systemic insulin resistance diseases, including reduced insulin-stimulated growth and survival signaling, increased oxidative stress, proinflammatory cytokine activation, mitochondrial dysfunction, impaired energy metabolism and altered protein homeostasis. Reduced glucose utilization and energy metabolism in AD brain is associated with the accumulation of: 1) Aβ peptide and hyperphosphorylated tau; 2) increased oxidative stress; 3) unfolded/misfolded proteins. mTOR, aberrantly activated in AD from its earliest stages, plays a key role in AD neurodegeneration by both inhibiting insulin signalling as a negative feedback mechanism and regulating protein homeostasis (synthesis/clearance). Employing the techniques of redox proteomics pioneered in our laboratory led to the identification of oxidatively modified brain proteins in AD involved in concomitant and mutual alterations of energy metabolism, mTOR signaling, and protein homeostasis. These proteins form a self-sustaining triangle of harmful events that trigger the degeneration and death of neurons and the development and progression of AD. Moreover, the altered crosstalk among the components of this “triangle of death”, beyond altering the redox homeostasis of neurons, is further exacerbated by increased levels of oxidative stress that target and impair key components of the pathways involved, thereby revealing the crucial role of oxidative stress in fueling this aberrant vicious cycle. This triangle of death may represent promising therapeutic targets to slow, delay, or prevent progression of AD.
doi: 10.1016/j.freeradbiomed.2016.10.414 374 The Synthetic Progestin Norgestrel Modulates Nrf2 Signaling and Acts as an Antioxidant in a Model of Retinal Degeneration Ashleigh Maria Byrne1 University College Cork, Ireland
1
SfRBM / SFRRI 2016
doi: 10.1016/j.freeradbiomed.2016.10.412 372 Neuronal Deletion of Manganese Superoxide Dismutase Altered TCA Cycle Metabolism and Caused Severe Peripheral Nerve Demyelination in Mice Marcio Buffolo1, Shaobo Pei1, Karla Maria Pereira-Pires1, Janaina Paulini2, Luciana Jorge2, and Sihem Boudina1 1 University of Utah, Salt Lake City, USA, 2São Paulo Federal University, Brazil Oxidative stress and mitochondrial dysfunction have been increasingly recognized as contributing factors for the pathogenesis of various diseases, including neurodegenerative diseases. Manganese superoxide dismutase (MnSOD) is the sole mitochondrial matrix enzyme that converts dismutate superoxide to hydrogen peroxide. Previous studies investigating the role of MnSOD in the central nervous system have used mice lacking this enzyme in neuronal stem cells and showed perinatal lethality and severe growth retardation. However, the underlying mechanisms for the phenotype of brain-specific MnSOD knockout (BSOD) mice is not well understood. Here used BSOD mice on a C57B background and show that mitochondrial function was preserved in whole brain sections despite increased superoxide levels. We also demonstrated that BSOD mice fail to feed at about post-natal day 15 and develop severe diabetic ketoacidosis. Although the overall morphology of the central nervous system was not altered in BSOD mice, peripheral nerves ultrastructure was severely affected as
S158
evidenced by myelin delamination. Interestingly, metabolomic analysis of the sciatic nerves of BSOD mice showed reduced polyol pathway and increased glycerol levels. Furthermore, there was a massive accumulation of the oncometabolite 2-hydroxyglutarate both in whole brain homogenates and in sciatic nerves of BSOD mice. Taken together, these results indicate that MnSOD deletion in neuronal cells causes peripheral neuropathy in part via impairment of mitochondrial metabolism.
doi: 10.1016/j.freeradbiomed.2016.10.413 373 Oxidative Stress and the Triangle of Death in Alzheimer Disease Brain: The Aberrant Crosstalk among Energy Metabolism, MTOR Signaling and Protein Homeostasis Revealed by Redox Proteomics D. Allan Butterfield1, Eugenio Barone2, Marzia Perluigi2, and Fabio Di Domenico2 1 University of Kentucky, Lexington, USA, 2University of Rome La Sapienza, Italy Alzheimer disease (AD), a multifactorial neurodegenerative disorder that represents one of the most disabling conditions in the aged population, shares many features in common with systemic insulin resistance diseases, including reduced insulin-stimulated growth and survival signaling, increased oxidative stress, proinflammatory cytokine activation, mitochondrial dysfunction, impaired energy metabolism and altered protein homeostasis. Reduced glucose utilization and energy metabolism in AD brain is associated with the accumulation of: 1) Aβ peptide and hyperphosphorylated tau; 2) increased oxidative stress; 3) unfolded/misfolded proteins. mTOR, aberrantly activated in AD from its earliest stages, plays a key role in AD neurodegeneration by both inhibiting insulin signalling as a negative feedback mechanism and regulating protein homeostasis (synthesis/clearance). Employing the techniques of redox proteomics pioneered in our laboratory led to the identification of oxidatively modified brain proteins in AD involved in concomitant and mutual alterations of energy metabolism, mTOR signaling, and protein homeostasis. These proteins form a self-sustaining triangle of harmful events that trigger the degeneration and death of neurons and the development and progression of AD. Moreover, the altered crosstalk among the components of this “triangle of death”, beyond altering the redox homeostasis of neurons, is further exacerbated by increased levels of oxidative stress that target and impair key components of the pathways involved, thereby revealing the crucial role of oxidative stress in fueling this aberrant vicious cycle. This triangle of death may represent promising therapeutic targets to slow, delay, or prevent progression of AD.
doi: 10.1016/j.freeradbiomed.2016.10.414 374 The Synthetic Progestin Norgestrel Modulates Nrf2 Signaling and Acts as an Antioxidant in a Model of Retinal Degeneration Ashleigh Maria Byrne1 University College Cork, Ireland
1
SfRBM / SFRRI 2016