151
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Williams PA, Harder JM, John SWM. Glaucoma as a Metabolic Optic Neuropathy: Making the Case for Nicotinamide Treatment in Glaucoma. J Glaucoma 2017; 26:1161-1168. [PMID: 28858158 PMCID: PMC5854489 DOI: 10.1097/ijg.0000000000000767] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mitochondrial dysfunction may be an important, if not essential, component of human glaucoma. Using transcriptomics followed by molecular and neurobiological techniques, we have recently demonstrated that mitochondrial dysfunction within retinal ganglion cells is an early feature in the DBA/2J mouse model of inherited glaucoma. Guided by these findings, we discovered that the retinal level of nicotinamide adenine dinucleotide (NAD, a key molecule for mitochondrial health) declines in an age-dependent manner. We hypothesized that this decline in NAD renders retinal ganglion cells susceptible to damage during periods of elevated intraocular pressure. To replete NAD levels in this glaucoma, we administered nicotinamide (the amide of vitamin B3). At the lowest dose tested, nicotinamide robustly protected from glaucoma (~70% of eyes had no detectable glaucomatous neurodegeneration). At this dose, nicotinamide had no influence on intraocular pressure and so its effect was neuroprotective. At the highest dose tested, 93% of eyes had no detectable glaucoma. This represents a ~10-fold decrease in the risk of developing glaucoma. At this dose, intraocular pressure still became elevated but there was a reduction in the degree of elevation showing an additional benefit. Thus, nicotinamide is unexpectedly potent at preventing this glaucoma and is an attractive option for glaucoma therapeutics. Our findings demonstrate the promise for both preventing and treating glaucoma by interventions that bolster metabolism during increasing age and during periods of elevated intraocular pressure. Nicotinamide prevents age-related declines in NAD (a decline that occurs in different genetic contexts and species). NAD precursors are reported to protect from a variety of neurodegenerative conditions. Thus, nicotinamide may provide a much needed neuroprotective treatment against human glaucoma. This manuscript summarizes human data implicating mitochondria in glaucoma, and argues for studies to further assess the safety and efficacy of nicotinamide in human glaucoma care.
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Affiliation(s)
- Pete A Williams
- The Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME, USA
| | - Jeffrey M Harder
- The Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME, USA
| | - Simon W M John
- The Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME, USA
- Department of Ophthalmology, Tufts University of Medicine, Boston, MA, USA
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152
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Feinberg K, Kolaj A, Wu C, Grinshtein N, Krieger JR, Moran MF, Rubin LL, Miller FD, Kaplan DR. A neuroprotective agent that inactivates prodegenerative TrkA and preserves mitochondria. J Cell Biol 2017; 216:3655-3675. [PMID: 28877995 PMCID: PMC5674898 DOI: 10.1083/jcb.201705085] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/26/2017] [Accepted: 08/01/2017] [Indexed: 12/15/2022] Open
Abstract
The pan-kinase inhibitor foretinib is identified as a potent suppressor of sympathetic, sensory, and motor neuron axon degeneration, acting in part by inhibiting the activity of the unliganded TrkA/nerve growth factor receptor and by preserving mitochondria in die-back and Wallerian degeneration models. Axon degeneration is an early event and pathological in neurodegenerative conditions and nerve injuries. To discover agents that suppress neuronal death and axonal degeneration, we performed drug screens on primary rodent neurons and identified the pan-kinase inhibitor foretinib, which potently rescued sympathetic, sensory, and motor wt and SOD1 mutant neurons from trophic factor withdrawal-induced degeneration. By using primary sympathetic neurons grown in mass cultures and Campenot chambers, we show that foretinib protected neurons by suppressing both known degenerative pathways and a new pathway involving unliganded TrkA and transcriptional regulation of the proapoptotic BH3 family members BimEL, Harakiri,and Puma, culminating in preservation of mitochondria in the degenerative setting. Foretinib delayed chemotherapy-induced and Wallerian axonal degeneration in culture by preventing axotomy-induced local energy deficit and preserving mitochondria, and peripheral Wallerian degeneration in vivo. These findings identify a new axon degeneration pathway and a potentially clinically useful therapeutic drug.
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Affiliation(s)
- Konstantin Feinberg
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, ON, Canada
| | - Adelaida Kolaj
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Chen Wu
- Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Harvard University, Cambridge, MA
| | - Natalie Grinshtein
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, ON, Canada
| | - Jonathan R Krieger
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada
| | - Michael F Moran
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Lee L Rubin
- Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Harvard University, Cambridge, MA
| | - Freda D Miller
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, ON, Canada .,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - David R Kaplan
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, ON, Canada .,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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153
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Fukuda Y, Li Y, Segal RA. A Mechanistic Understanding of Axon Degeneration in Chemotherapy-Induced Peripheral Neuropathy. Front Neurosci 2017; 11:481. [PMID: 28912674 PMCID: PMC5583221 DOI: 10.3389/fnins.2017.00481] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/14/2017] [Indexed: 12/12/2022] Open
Abstract
Chemotherapeutic agents cause many short and long term toxic side effects to peripheral nervous system (PNS) that drastically alter quality of life. Chemotherapy-induced peripheral neuropathy (CIPN) is a common and enduring disorder caused by several anti-neoplastic agents. CIPN typically presents with neuropathic pain, numbness of distal extremities, and/or oversensitivity to thermal or mechanical stimuli. This adverse side effect often requires a reduction in chemotherapy dosage or even discontinuation of treatment. Currently there are no effective treatment options for CIPN. While the underlying mechanisms for CIPN are not understood, current data identify a “dying back” axon degeneration of distal nerve endings as the major pathology in this disorder. Therefore, mechanistic understanding of axon degeneration will provide insights into the pathway and molecular players responsible for CIPN. Here, we review recent findings that expand our understanding of the pathogenesis of CIPN and discuss pathways that may be shared with the axonal degeneration that occurs during developmental axon pruning and during injury-induced Wallerian degeneration. These mechanistic insights provide new avenues for development of therapies to prevent or treat CIPN.
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Affiliation(s)
- Yusuke Fukuda
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
| | - Yihang Li
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
| | - Rosalind A Segal
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
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154
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Vaur P, Brugg B, Mericskay M, Li Z, Schmidt MS, Vivien D, Orset C, Jacotot E, Brenner C, Duplus E. Nicotinamide riboside, a form of vitamin B 3, protects against excitotoxicity-induced axonal degeneration. FASEB J 2017; 31:5440-5452. [PMID: 28842432 DOI: 10.1096/fj.201700221rr] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/31/2017] [Indexed: 11/11/2022]
Abstract
NAD+ depletion is a common phenomenon in neurodegenerative pathologies. Excitotoxicity occurs in multiple neurologic disorders and NAD+ was shown to prevent neuronal degeneration in this process through mechanisms that remained to be determined. The activity of nicotinamide riboside (NR) in neuroprotective models and the recent description of extracellular conversion of NAD+ to NR prompted us to probe the effects of NAD+ and NR in protection against excitotoxicity. Here, we show that intracortical administration of NR but not NAD+ reduces brain damage induced by NMDA injection. Using cortical neurons, we found that provision of extracellular NR delays NMDA-induced axonal degeneration (AxD) much more strongly than extracellular NAD+ Moreover, the stronger effect of NR compared to NAD+ depends of axonal stress since in AxD induced by pharmacological inhibition of nicotinamide salvage, both NAD+ and NR prevent neuronal death and AxD in a manner that depends on internalization of NR. Taken together, our findings demonstrate that NR is a better neuroprotective agent than NAD+ in excitotoxicity-induced AxD and that axonal protection involves defending intracellular NAD+ homeostasis.-Vaur, P., Brugg, B., Mericskay, M., Li, Z., Schmidt, M. S., Vivien, D., Orset, C., Jacotot, E., Brenner, C., Duplus, E. Nicotinamide riboside, a form of vitamin B3, protects against excitotoxicity-induced axonal degeneration.
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Affiliation(s)
- Pauline Vaur
- Unité Mixte de Recherche (UMR) Adaptation Biologique et Vieillissement (UMR 8256), Institut Biologie Paris Seine, Centre National de la Recherche Scientifique (CNRS), INSERM, Université Pierre et Marie Curie (UPMC), Sorbonne Universités, Paris, France
| | - Bernard Brugg
- Unité Mixte de Recherche (UMR) Adaptation Biologique et Vieillissement (UMR 8256), Institut Biologie Paris Seine, Centre National de la Recherche Scientifique (CNRS), INSERM, Université Pierre et Marie Curie (UPMC), Sorbonne Universités, Paris, France
| | - Mathias Mericskay
- Unité Mixte de Recherche (UMR) Adaptation Biologique et Vieillissement (UMR 8256), Institut Biologie Paris Seine, Centre National de la Recherche Scientifique (CNRS), INSERM, Université Pierre et Marie Curie (UPMC), Sorbonne Universités, Paris, France.,Unité Signalisation et Physiopathologie Cardiovasculaire, INSERM, Université Paris-Saclay, Université Paris Sud, Châtenay-Malabry, France
| | - Zhenlin Li
- Unité Mixte de Recherche (UMR) Adaptation Biologique et Vieillissement (UMR 8256), Institut Biologie Paris Seine, Centre National de la Recherche Scientifique (CNRS), INSERM, Université Pierre et Marie Curie (UPMC), Sorbonne Universités, Paris, France.,Equipe de Recherche Labellisée (ERL) U1164, INSERM, Université Paris-Saclay, Université Paris Sud, Châtenay-Malabry, France
| | - Mark S Schmidt
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Denis Vivien
- Unité INSERM 1237, GIP Cycéron, Centre Hospitalier Universitaire de Caen, Université Caen Normandie, Caen, France
| | - Cyrille Orset
- Unité INSERM 1237, GIP Cycéron, Centre Hospitalier Universitaire de Caen, Université Caen Normandie, Caen, France
| | - Etienne Jacotot
- Unité Mixte de Recherche (UMR) Adaptation Biologique et Vieillissement (UMR 8256), Institut Biologie Paris Seine, Centre National de la Recherche Scientifique (CNRS), INSERM, Université Pierre et Marie Curie (UPMC), Sorbonne Universités, Paris, France
| | - Charles Brenner
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Eric Duplus
- Unité Mixte de Recherche (UMR) Adaptation Biologique et Vieillissement (UMR 8256), Institut Biologie Paris Seine, Centre National de la Recherche Scientifique (CNRS), INSERM, Université Pierre et Marie Curie (UPMC), Sorbonne Universités, Paris, France;
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155
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NMN Deamidase Delays Wallerian Degeneration and Rescues Axonal Defects Caused by NMNAT2 Deficiency In Vivo. Curr Biol 2017; 27:784-794. [PMID: 28262487 DOI: 10.1016/j.cub.2017.01.070] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 11/22/2022]
Abstract
Axons require the axonal NAD-synthesizing enzyme NMNAT2 to survive. Injury or genetically induced depletion of NMNAT2 triggers axonal degeneration or defective axon growth. We have previously proposed that axonal NMNAT2 primarily promotes axon survival by maintaining low levels of its substrate NMN rather than generating NAD; however, this is still debated. NMN deamidase, a bacterial enzyme, shares NMN-consuming activity with NMNAT2, but not NAD-synthesizing activity, and it delays axon degeneration in primary neuronal cultures. Here we show that NMN deamidase can also delay axon degeneration in zebrafish larvae and in transgenic mice. Like overexpressed NMNATs, NMN deamidase reduces NMN accumulation in injured mouse sciatic nerves and preserves some axons for up to three weeks, even when expressed at a low level. Remarkably, NMN deamidase also rescues axonal outgrowth and perinatal lethality in a dose-dependent manner in mice lacking NMNAT2. These data further support a pro-degenerative effect of accumulating NMN in axons in vivo. The NMN deamidase mouse will be an important tool to further probe the mechanisms underlying Wallerian degeneration and its prevention.
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156
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Williams PA, Harder JM, Foxworth NE, Cochran KE, Philip VM, Porciatti V, Smithies O, John SWM. Vitamin B 3 modulates mitochondrial vulnerability and prevents glaucoma in aged mice. Science 2017; 355:756-760. [PMID: 28209901 PMCID: PMC5408298 DOI: 10.1126/science.aal0092] [Citation(s) in RCA: 370] [Impact Index Per Article: 52.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 12/23/2016] [Indexed: 12/25/2022]
Abstract
Glaucomas are neurodegenerative diseases that cause vision loss, especially in the elderly. The mechanisms initiating glaucoma and driving neuronal vulnerability during normal aging are unknown. Studying glaucoma-prone mice, we show that mitochondrial abnormalities are an early driver of neuronal dysfunction, occurring before detectable degeneration. Retinal levels of nicotinamide adenine dinucleotide (NAD+, a key molecule in energy and redox metabolism) decrease with age and render aging neurons vulnerable to disease-related insults. Oral administration of the NAD+ precursor nicotinamide (vitamin B3), and/or gene therapy (driving expression of Nmnat1, a key NAD+-producing enzyme), was protective both prophylactically and as an intervention. At the highest dose tested, 93% of eyes did not develop glaucoma. This supports therapeutic use of vitamin B3 in glaucoma and potentially other age-related neurodegenerations.
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Affiliation(s)
| | | | | | | | | | - Vittorio Porciatti
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Oliver Smithies
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Simon W M John
- The Jackson Laboratory, Bar Harbor, ME 04609, USA.
- Department of Ophthalmology, Tufts University of Medicine, Boston, MA 02111, USA
- The Howard Hughes Medical Institute, Bar Harbor, ME 04609, USA
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157
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Holland SM, Thomas GM. Roles of palmitoylation in axon growth, degeneration and regeneration. J Neurosci Res 2017; 95:1528-1539. [PMID: 28150429 DOI: 10.1002/jnr.24003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 11/09/2016] [Accepted: 11/28/2016] [Indexed: 12/11/2022]
Abstract
The protein-lipid modification palmitoylation plays important roles in neurons, but most attention has focused on roles of this modification in the regulation of mature pre- and post-synapses. However, exciting recent findings suggest that palmitoylation is also critical for both the growth and integrity of neuronal axons and plays previously unappreciated roles in conveying axonal anterograde and retrograde signals. Here we review these emerging roles for palmitoylation in the regulation of axons in health and disease. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Sabrina M Holland
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair)
| | - Gareth M Thomas
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair).,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA, 19140
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158
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Inhibitor of Nicotinamide Phosphoribosyltransferase Sensitizes Glioblastoma Cells to Temozolomide via Activating ROS/JNK Signaling Pathway. BIOMED RESEARCH INTERNATIONAL 2016; 2016:1450843. [PMID: 28097126 PMCID: PMC5206411 DOI: 10.1155/2016/1450843] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/10/2016] [Indexed: 12/16/2022]
Abstract
Overcoming temozolomide (TMZ) resistance is a great challenge in glioblastoma (GBM) treatment. Nicotinamide phosphoribosyltransferase (NAMPT) is a rate-limiting enzyme in the biosynthesis of nicotinamide adenine dinucleotide and has a crucial role in cancer cell metabolism. In this study, we investigated whether FK866 and CHS828, two specific NAMPT inhibitors, could sensitize GBM cells to TMZ. Low doses of FK866 and CHS828 (5 nM and 10 nM, resp.) alone did not significantly decrease cell viability in U251-MG and T98 GBM cells. However, they significantly increased the antitumor action of TMZ in these cells. In U251-MG cells, administration of NAMPT inhibitors increased the TMZ (100 μM)-induced apoptosis and LDH release from GBM cells. NAMPT inhibitors remarkably enhanced the activities of caspase-1, caspase-3, and caspase-9. Moreover, NAMPT inhibitors increased reactive oxygen species (ROS) production and superoxide anion level but reduced the SOD activity and total antioxidative capacity in GBM cells. Treatment of NAMPT inhibitors increased phosphorylation of c-Jun and JNK. Administration of JNK inhibitor SP600125 or ROS scavenger tocopherol with TMZ and NAMPT inhibitors substantially attenuated the sensitization of NAMPT inhibitor on TMZ antitumor action. Our data indicate a potential value of NAMPT inhibitors in combined use with TMZ for GBM treatment.
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159
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Chen L, Nye DM, Stone MC, Weiner AT, Gheres KW, Xiong X, Collins CA, Rolls MM. Mitochondria and Caspases Tune Nmnat-Mediated Stabilization to Promote Axon Regeneration. PLoS Genet 2016; 12:e1006503. [PMID: 27923046 PMCID: PMC5173288 DOI: 10.1371/journal.pgen.1006503] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 12/20/2016] [Accepted: 11/22/2016] [Indexed: 11/24/2022] Open
Abstract
Axon injury can lead to several cell survival responses including increased stability and axon regeneration. Using an accessible Drosophila model system, we investigated the regulation of injury responses and their relationship. Axon injury stabilizes the rest of the cell, including the entire dendrite arbor. After axon injury we found mitochondrial fission in dendrites was upregulated, and that reducing fission increased stabilization or neuroprotection (NP). Thus axon injury seems to both turn on NP, but also dampen it by activating mitochondrial fission. We also identified caspases as negative regulators of axon injury-mediated NP, so mitochondrial fission could control NP through caspase activation. In addition to negative regulators of NP, we found that nicotinamide mononucleotide adenylyltransferase (Nmnat) is absolutely required for this type of NP. Increased microtubule dynamics, which has previously been associated with NP, required Nmnat. Indeed Nmnat overexpression was sufficient to induce NP and increase microtubule dynamics in the absence of axon injury. DLK, JNK and fos were also required for NP. Because NP occurs before axon regeneration, and NP seems to be actively downregulated, we tested whether excessive NP might inhibit regeneration. Indeed both Nmnat overexpression and caspase reduction reduced regeneration. In addition, overexpression of fos or JNK extended the timecourse of NP and dampened regeneration in a Nmnat-dependent manner. These data suggest that NP and regeneration are conflicting responses to axon injury, and that therapeutic strategies that boost NP may reduce regeneration. Unlike many other cell types, most neurons last a lifetime. When injured, these cells often activate survival and repair strategies rather than dying. One such response is regeneration of the axon after it is injured. Axon regeneration is a conserved process activated by the same signaling cascade in worms, flies and mammals. Surprisingly we find that this signaling cascade first initiates a different response. This first response stabilizes the cell, and its downregulation by mitochondrial fission and caspases allows for maximum regeneration at later times. We propose that neurons respond to axon injury in a multi-step process with an early lock-down phase in which the cell is stabilized, followed by a more plastic state in which regeneration is maximized.
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Affiliation(s)
- Li Chen
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Derek M. Nye
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Michelle C. Stone
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Alexis T. Weiner
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Kyle W. Gheres
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Xin Xiong
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Catherine A. Collins
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Melissa M. Rolls
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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160
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Sasaki Y, Nakagawa T, Mao X, DiAntonio A, Milbrandt J. NMNAT1 inhibits axon degeneration via blockade of SARM1-mediated NAD + depletion. eLife 2016; 5. [PMID: 27735788 PMCID: PMC5063586 DOI: 10.7554/elife.19749] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Accepted: 09/24/2016] [Indexed: 12/11/2022] Open
Abstract
Overexpression of the NAD+ biosynthetic enzyme NMNAT1 leads to preservation of injured axons. While increased NAD+ or decreased NMN levels are thought to be critical to this process, the mechanism(s) of this axon protection remain obscure. Using steady-state and flux analysis of NAD+ metabolites in healthy and injured mouse dorsal root ganglion axons, we find that rather than altering NAD+ synthesis, NMNAT1 instead blocks the injury-induced, SARM1-dependent NAD+ consumption that is central to axon degeneration.
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Affiliation(s)
- Yo Sasaki
- Department of Genetics, Washington University School of Medicine, Saint Louis, United States
| | - Takashi Nakagawa
- Frontier Research Core for Life Sciences, University of Toyama, Toyama, Japan
| | - Xianrong Mao
- Department of Genetics, Washington University School of Medicine, Saint Louis, United States
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine, Saint Louis, United States
| | - Jeffrey Milbrandt
- Department of Genetics, Washington University School of Medicine, Saint Louis, United States
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161
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Bramley JC, Collins SVA, Clark KB, Buchser WJ. Avian axons undergo Wallerian degeneration after injury and stress. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2016; 202:813-822. [PMID: 27614771 DOI: 10.1007/s00359-016-1123-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 06/20/2016] [Accepted: 08/31/2016] [Indexed: 12/22/2022]
Abstract
The integrity of long axons is essential for neural communication. Unfortunately, relatively minor stress to a neuron can cause extensive loss of this integrity. Axon degeneration is the cell-intrinsic program that actively deconstructs an axon after injury or damage. Although ultrastructural examination has revealed signs of axon degeneration in vivo, the occurrence and progression of axon degeneration in avian species have not yet been documented in vitro. Here, we use a novel cell culture system with primary embryonic zebra finch retinal ganglion cells to interrogate the properties of avian axon degeneration. First, we establish that both axotomy and a chemically induced injury (taxol and vincristine) are sufficient to initiate degeneration. These events are dependent on a late influx of calcium. In addition, as in mammals, the NAD pathway is involved, since a decrease in NMN with FK866 can reduce degeneration. Importantly, these retinal ganglion cell axons were sensitive to a pressure-induced injury, which may mimic the effect of high intraocular pressure associated with glaucoma. We have demonstrated that avian neurons undergo Wallerian degeneration in response to both physical and chemical injury. Subsequent avian studies will investigate whether blocking the degeneration pathway can protect individuals from neurodegenerative disease.
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Affiliation(s)
- John C Bramley
- Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA, USA
| | - Samantha V A Collins
- Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA, USA
| | - Karen B Clark
- Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA, USA
| | - William J Buchser
- Department of Biology, College of William & Mary, 540 Landrum Dr., Williamsburg, VA, USA.
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162
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Human serine racemase is allosterically modulated by NADH and reduced nicotinamide derivatives. Biochem J 2016; 473:3505-3516. [PMID: 27493223 DOI: 10.1042/bcj20160566] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/04/2016] [Indexed: 11/17/2022]
Abstract
Serine racemase catalyzes both the synthesis and the degradation of d-serine, an obligatory co-agonist of the glutamatergic NMDA receptors. It is allosterically controlled by adenosine triphosphate (ATP), which increases its activity around 7-fold through a co-operative binding mechanism. Serine racemase has been proposed as a drug target for the treatment of several neuropathologies but, so far, the search has been directed only toward the active site, with the identification of a few, low-affinity inhibitors. Following the recent observation that nicotinamide adenine dinucleotide (reduced form) (NADH) inhibits serine racemase, here we show that the inhibition is partial, with an IC50 of 246 ± 63 μM, several-fold higher than NADH intracellular concentrations. At saturating concentrations of NADH, ATP binds with a 2-fold lower affinity and without co-operativity, suggesting ligand competition. NADH also reduces the weak activity of human serine racemase in the absence of ATP, indicating an additional ATP-independent inhibition mechanism. By dissecting the NADH molecule, we discovered that the inhibitory determinant is the N-substituted 1,4-dihydronicotinamide ring. Particularly, the NADH precursor 1,4-dihydronicotinamide mononucleotide exhibited a partial mixed-type inhibition, with a KI of 18 ± 7 μM. Docking simulations suggested that all 1,4-dihydronicotinamide derivatives bind at the interdimeric interface, with the ring positioned in an unoccupied site next to the ATP-binding site. This newly recognized allosteric site might be exploited for the design of high-affinity serine racemase effectors to finely modulate d-serine homeostasis.
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163
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Nicotinamide mononucleotide inhibits post-ischemic NAD(+) degradation and dramatically ameliorates brain damage following global cerebral ischemia. Neurobiol Dis 2016; 95:102-10. [PMID: 27425894 DOI: 10.1016/j.nbd.2016.07.018] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/17/2016] [Accepted: 07/13/2016] [Indexed: 01/22/2023] Open
Abstract
Nicotinamide adenine dinucleotide (NAD(+)) is an essential cofactor for multiple cellular metabolic reactions and has a central role in energy production. Brain ischemia depletes NAD(+) pools leading to bioenergetics failure and cell death. Nicotinamide mononucleotide (NMN) is utilized by the NAD(+) salvage pathway enzyme, nicotinamide adenylyltransferase (Nmnat) to generate NAD(+). Therefore, we examined whether NMN could protect against ischemic brain damage. Mice were subjected to transient forebrain ischemia and treated with NMN or vehicle at the start of reperfusion or 30min after the ischemic insult. At 2, 4, and 24h of recovery, the proteins poly-ADP-ribosylation (PAR), hippocampal NAD(+) levels, and expression levels of NAD(+) salvage pathway enzymes were determined. Furthermore, animal's neurologic outcome and hippocampal CA1 neuronal death was assessed after six days of reperfusion. NMN (62.5mg/kg) dramatically ameliorated the hippocampal CA1 injury and significantly improved the neurological outcome. Additionally, the post-ischemic NMN treatment prevented the increase in PAR formation and NAD(+) catabolism. Since the NMN administration did not affect animal's temperature, blood gases or regional cerebral blood flow during recovery, the protective effect was not a result of altered reperfusion conditions. These data suggest that administration of NMN at a proper dosage has a strong protective effect against ischemic brain injury.
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164
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Ali YO, Allen HM, Yu L, Li-Kroeger D, Bakhshizadehmahmoudi D, Hatcher A, McCabe C, Xu J, Bjorklund N, Taglialatela G, Bennett DA, De Jager PL, Shulman JM, Bellen HJ, Lu HC. NMNAT2:HSP90 Complex Mediates Proteostasis in Proteinopathies. PLoS Biol 2016; 14:e1002472. [PMID: 27254664 PMCID: PMC4890852 DOI: 10.1371/journal.pbio.1002472] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 04/28/2016] [Indexed: 12/02/2022] Open
Abstract
Nicotinamide mononucleotide adenylyl transferase 2 (NMNAT2) is neuroprotective in numerous preclinical models of neurodegeneration. Here, we show that brain nmnat2 mRNA levels correlate positively with global cognitive function and negatively with AD pathology. In AD brains, NMNAT2 mRNA and protein levels are reduced. NMNAT2 shifts its solubility and colocalizes with aggregated Tau in AD brains, similar to chaperones, which aid in the clearance or refolding of misfolded proteins. Investigating the mechanism of this observation, we discover a novel chaperone function of NMNAT2, independent from its enzymatic activity. NMNAT2 complexes with heat shock protein 90 (HSP90) to refold aggregated protein substrates. NMNAT2’s refoldase activity requires a unique C-terminal ATP site, activated in the presence of HSP90. Furthermore, deleting NMNAT2 function increases the vulnerability of cortical neurons to proteotoxic stress and excitotoxicity. Interestingly, NMNAT2 acts as a chaperone to reduce proteotoxic stress, while its enzymatic activity protects neurons from excitotoxicity. Taken together, our data indicate that NMNAT2 exerts its chaperone or enzymatic function in a context-dependent manner to maintain neuronal health. This study reveals NMNAT2 to be a dual-function neuronal maintenance factor that not only generates NAD to protect neurons from excitotoxicity but also moonlights as a chaperone to combat protein toxicity. Pathological protein aggregates are found in many neurodegenerative diseases, and it has been hypothesized that these protein aggregates are toxic and cause neuronal death. Little is known about how neurons protect against pathological protein aggregates to maintain their health. Nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2) is a newly identified neuronal maintenance factor. We found that in humans, levels of NMNAT2 transcript are positively correlated with cognitive function and are negatively correlated with pathological features of neurodegenerative disease like plaques and tangles. In this study, we demonstrate that NMNAT2 can act as a chaperone to reduce protein aggregates, and this function is independent from its known function in the enzymatic synthesis of nicotinamide adenine dinucleotide (NAD). We find that NMNAT2 interacts with heat shock protein 90 (HSP90) to refold protein aggregates, and that deleting NMNAT2 in cortical neurons renders them vulnerable to protein stress or excitotoxicity. Interestingly, the chaperone function of NMNAT2 protects neurons from protein toxicity, while its enzymatic function is required to defend against excitotoxicity. Our work here suggests that NMNAT2 uses either its chaperone or enzymatic function to combat neuronal insults in a context-dependent manner. In Alzheimer disease brains, NMNAT2 levels are less than 50% of control levels, and we propose that enhancing NMNAT2 function may provide an effective therapeutic intervention to reserve cognitive function.
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Affiliation(s)
- Yousuf O. Ali
- Linda and Jack Gill Center, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
- The Cain Foundation Laboratories, Texas Children’s Hospital, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hunter M. Allen
- Linda and Jack Gill Center, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
- The Cain Foundation Laboratories, Texas Children’s Hospital, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
| | - Lei Yu
- Rush Alzheimer’s Disease Center and Department of Neurological Sciences, Rush University, Chicago, Illinois, United States of America
| | - David Li-Kroeger
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Dena Bakhshizadehmahmoudi
- Linda and Jack Gill Center, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
- The Cain Foundation Laboratories, Texas Children’s Hospital, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Asante Hatcher
- The Cain Foundation Laboratories, Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Cristin McCabe
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, United States of America
| | - Jishu Xu
- Program in Translational NeuroPsychiatric Genomics, Institute for the Neurosciences, Departments of Neurology and Psychiatry, Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Nicole Bjorklund
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Giulio Taglialatela
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - David A. Bennett
- Rush Alzheimer’s Disease Center and Department of Neurological Sciences, Rush University, Chicago, Illinois, United States of America
| | - Philip L. De Jager
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, United States of America
- Program in Translational NeuroPsychiatric Genomics, Institute for the Neurosciences, Departments of Neurology and Psychiatry, Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
| | - Joshua M. Shulman
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neurology, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hugo J. Bellen
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute (HHMI), Baylor College of Medicine, Houston, Texas, United States of America
| | - Hui-Chen Lu
- Linda and Jack Gill Center, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
- The Cain Foundation Laboratories, Texas Children’s Hospital, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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165
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Chang B, Quan Q, Lu S, Wang Y, Peng J. Molecular mechanisms in the initiation phase of Wallerian degeneration. Eur J Neurosci 2016; 44:2040-8. [PMID: 27062141 DOI: 10.1111/ejn.13250] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 04/06/2016] [Accepted: 04/06/2016] [Indexed: 12/20/2022]
Abstract
Axonal degeneration is an early hallmark of nerve injury and many neurodegenerative diseases. The discovery of the Wallerian degeneration slow mutant mouse, in which axonal degeneration is delayed, revealed that Wallerian degeneration is an active progress and thereby illuminated the mechanisms underlying axonal degeneration. Nicotinamide mononucleotide adenylyltransferase 2 and sterile alpha and armadillo motif-containing protein 1 play essential roles in the maintenance of axon integrity by regulating the level of nicotinamide adenine dinucleotide, which seems to be the key molecule involved in the maintenance of axonal health. However, the function of nicotinamide mononucleotide remains debatable, and we discuss two apparently conflicting roles of nicotinamide mononucleotide in Wallerian degeneration. In this article, we focus on the roles of these molecules in the initiation phase of Wallerian degeneration to improve our understanding of the mechanisms underpinning this phenomenon.
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Affiliation(s)
- Biao Chang
- Institute of Orthopedics, General Hospital of People's Liberation Army, 28th Fuxing Road, Beijing, China.,Beijing Key Laboratory of Regenerative Medicine in Orthopedics, Beijing, China.,Key Laboratory of Musculoskeletal Trauma & War Injuries, People's Liberation Army, Beijing, China
| | - Qi Quan
- Institute of Orthopedics, General Hospital of People's Liberation Army, 28th Fuxing Road, Beijing, China.,Beijing Key Laboratory of Regenerative Medicine in Orthopedics, Beijing, China.,Key Laboratory of Musculoskeletal Trauma & War Injuries, People's Liberation Army, Beijing, China
| | - Shibi Lu
- Institute of Orthopedics, General Hospital of People's Liberation Army, 28th Fuxing Road, Beijing, China.,Beijing Key Laboratory of Regenerative Medicine in Orthopedics, Beijing, China.,Key Laboratory of Musculoskeletal Trauma & War Injuries, People's Liberation Army, Beijing, China
| | - Yu Wang
- Institute of Orthopedics, General Hospital of People's Liberation Army, 28th Fuxing Road, Beijing, China.,Beijing Key Laboratory of Regenerative Medicine in Orthopedics, Beijing, China.,Key Laboratory of Musculoskeletal Trauma & War Injuries, People's Liberation Army, Beijing, China.,The Neural Regeneration Co-innovation Center of Jiangsu Province, Nantong, China
| | - Jiang Peng
- Institute of Orthopedics, General Hospital of People's Liberation Army, 28th Fuxing Road, Beijing, China.,Beijing Key Laboratory of Regenerative Medicine in Orthopedics, Beijing, China.,Key Laboratory of Musculoskeletal Trauma & War Injuries, People's Liberation Army, Beijing, China.,The Neural Regeneration Co-innovation Center of Jiangsu Province, Nantong, China
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166
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Axon degeneration: context defines distinct pathways. Curr Opin Neurobiol 2016; 39:108-15. [PMID: 27197022 DOI: 10.1016/j.conb.2016.05.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/02/2016] [Accepted: 05/03/2016] [Indexed: 12/29/2022]
Abstract
Axon degeneration is an essential part of development, plasticity, and injury response and has been primarily studied in mammalian models in three contexts: 1) Axotomy-induced Wallerian degeneration, 2) Apoptosis-induced axon degeneration (axon apoptosis), and 3) Axon pruning. These three contexts dictate engagement of distinct pathways for axon degeneration. Recent advances have identified the importance of SARM1, NMNATs, NAD+ depletion, and MAPK signaling in axotomy-induced Wallerian degeneration. Interestingly, apoptosis-induced axon degeneration and axon pruning have many shared mechanisms both in signaling (e.g. DLK, JNKs, GSK3α/β) and execution (e.g. Puma, Bax, caspase-9, caspase-3). However, the specific mechanisms by which caspases are activated during apoptosis versus pruning appear distinct, with apoptosis requiring Apaf-1 but not caspase-6 while pruning requires caspase-6 but not Apaf-1.
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167
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Application of virtual screening to the discovery of novel nicotinamide phosphoribosyltransferase (NAMPT) inhibitors with potential for the treatment of cancer and axonopathies. Bioorg Med Chem Lett 2016; 26:2920-2926. [PMID: 27158141 DOI: 10.1016/j.bmcl.2016.04.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 04/14/2016] [Accepted: 04/15/2016] [Indexed: 11/22/2022]
Abstract
NAMPT may represent a novel target for drug discovery in various therapeutic areas, including oncology and inflammation. Additionally, recent work has suggested that targeting NAMPT has potential in treating axon degeneration. In this work, publicly available X-ray co-crystal structures of NAMPT and the structures of two known NAMPT inhibitors were used as the basis for a structure- and ligand-based virtual screening campaign. From this, two novel series of NAMPT inhibitors were identified, one of which showed a statistically significant protective effect when tested in a cellular model of axon degeneration.
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168
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Traumatic Axonal Injury: Mechanisms and Translational Opportunities. Trends Neurosci 2016; 39:311-324. [PMID: 27040729 PMCID: PMC5405046 DOI: 10.1016/j.tins.2016.03.002] [Citation(s) in RCA: 188] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 12/22/2022]
Abstract
Traumatic axonal injury (TAI) is an important pathoanatomical subgroup of traumatic brain injury (TBI) and a major driver of mortality and functional impairment. Experimental models have provided insights into the effects of mechanical deformation on the neuronal cytoskeleton and the subsequent processes that drive axonal injury. There is also increasing recognition that axonal or white matter loss may progress for years post-injury and represent one mechanistic framework for progressive neurodegeneration after TBI. Previous trials of novel therapies have failed to make an impact on clinical outcome, in both TBI in general and TAI in particular. Recent advances in understanding the cellular and molecular mechanisms of injury have the potential to translate into novel therapeutic targets. Multiple therapeutic targets are emerging that offer the potential to reduce secondary brain injury at a cellular level. These include cytoskeletal and membrane stabilisation, control of calcium flux and calpain activation, optimisation of cellular energetics, and modulation of the inflammatory response. Wallerian degeneration, as occurs following an axonal injury, is an active, cell-autonomous death pathway that involves failure of axonal transport to deliver key enzymes involved in NAD biosynthesis. Chronic microglial activation occurs following traumatic brain injury (TBI) and may persist for decades afterwards. This ongoing response has been linked to long-term neurodegeneration, particularly of white matter tracts. Phagoptosis is the process whereby physiologically stressed but otherwise viable neurons are phagocytosed by microglia in response to a range of eat-me signals induced by tissue injury.
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169
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French SW. Chronic alcohol binging injures the liver and other organs by reducing NAD⁺ levels required for sirtuin's deacetylase activity. Exp Mol Pathol 2016; 100:303-6. [PMID: 26896648 DOI: 10.1016/j.yexmp.2016.02.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 02/15/2016] [Indexed: 01/07/2023]
Abstract
NAD(+) levels are markedly reduced when blood alcohol levels are high during binge drinking. This causes liver injury to occur because the enzymes that require NAD(+) as a cofactor such as the sirtuin de-acetylases cannot de-acetylate acetylated proteins such as acetylated histones. This prevents the epigenetic changes that regulate metabolic processes and which prevent organ injury such as fatty liver in response to alcohol abuse. Hyper acetylation of numerous regulatory proteins develops. Systemic multi-organ injury occurs when NAD(+) is reduced. For instance the Circadian clock is altered if NAD(+) is not available. Cell cycle arrest occurs due to up regulation of cell cycle inhibitors leading to DNA damage, mutations, apoptosis and tumorigenesis. NAD(+) is linked to aging in the regulation of telomere stability. NAD(+) is required for mitochondrial renewal. Alcohol dehydrogenase is present in every visceral organ in the body so that there is a systemic reduction of NAD(+) levels in all of these organs during binge drinking.
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Affiliation(s)
- Samuel W French
- Harbor-UCLA Medical Center, Department of Pathology, Torrance, CA 90509, United States
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170
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Gerdts J, Summers DW, Milbrandt J, DiAntonio A. Axon Self-Destruction: New Links among SARM1, MAPKs, and NAD+ Metabolism. Neuron 2016; 89:449-60. [PMID: 26844829 PMCID: PMC4742785 DOI: 10.1016/j.neuron.2015.12.023] [Citation(s) in RCA: 243] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Wallerian axon degeneration is a form of programmed subcellular death that promotes axon breakdown in disease and injury. Active degeneration requires SARM1 and MAP kinases, including DLK, while the NAD+ synthetic enzyme NMNAT2 prevents degeneration. New studies reveal that these pathways cooperate in a locally mediated axon destruction program, with NAD+ metabolism playing a central role. Here, we review the biology of Wallerian-type axon degeneration and discuss the most recent findings, with special emphasis on critical signaling events and their potential as therapeutic targets for axonopathy.
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Affiliation(s)
- Josiah Gerdts
- Department of Genetics, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA
| | - Daniel W Summers
- Department of Genetics, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA; Department of Developmental Biology, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA
| | - Jeffrey Milbrandt
- Department of Genetics, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine in St. Louis, 660 Euclid Avenue, St. Louis, MO 63110, USA.
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171
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Mundinger TO, Cooper E, Coleman MP, Taborsky GJ. Short-term diabetic hyperglycemia suppresses celiac ganglia neurotransmission, thereby impairing sympathetically mediated glucagon responses. Am J Physiol Endocrinol Metab 2015; 309:E246-55. [PMID: 26037249 PMCID: PMC4525110 DOI: 10.1152/ajpendo.00140.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/25/2015] [Indexed: 01/09/2023]
Abstract
Short-term hyperglycemia suppresses superior cervical ganglia neurotransmission. If this ganglionic dysfunction also occurs in the islet sympathetic pathway, sympathetically mediated glucagon responses could be impaired. Our objectives were 1) to test for a suppressive effect of 7 days of streptozotocin (STZ) diabetes on celiac ganglia (CG) activation and on neurotransmitter and glucagon responses to preganglionic nerve stimulation, 2) to isolate the defect in the islet sympathetic pathway to the CG itself, and 3) to test for a protective effect of the WLD(S) mutation. We injected saline or nicotine in nondiabetic and STZ-diabetic rats and measured fos mRNA levels in whole CG. We electrically stimulated the preganglionic or postganglionic nerve trunk of the CG in nondiabetic and STZ-diabetic rats and measured portal venous norepinephrine and glucagon responses. We repeated the nicotine and preganglionic nerve stimulation studies in nondiabetic and STZ-diabetic WLD(S) rats. In STZ-diabetic rats, the CG fos response to nicotine was suppressed, and the norepinephrine and glucagon responses to preganglionic nerve stimulation were impaired. In contrast, the norepinephrine and glucagon responses to postganglionic nerve stimulation were normal. The CG fos response to nicotine, and the norepinephrine and glucagon responses to preganglionic nerve stimulation, were normal in STZ-diabetic WLD(S) rats. In conclusion, short-term hyperglycemia's suppressive effect on nicotinic acetylcholine receptors of the CG impairs sympathetically mediated glucagon responses. WLD(S) rats are protected from this dysfunction. The implication is that this CG dysfunction may contribute to the impaired glucagon response to insulin-induced hypoglycemia seen early in type 1 diabetes.
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MESH Headings
- Animals
- Diabetes Mellitus, Type 1/blood
- Diabetes Mellitus, Type 1/complications
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/physiopathology
- Down-Regulation/drug effects
- Electric Stimulation
- Ganglia, Sympathetic/drug effects
- Ganglia, Sympathetic/metabolism
- Ganglia, Sympathetic/physiopathology
- Ganglionic Stimulants/pharmacology
- Glucagon/blood
- Glucagon/metabolism
- Hyperglycemia/etiology
- Islets of Langerhans/drug effects
- Islets of Langerhans/innervation
- Islets of Langerhans/metabolism
- Male
- Mutant Proteins/metabolism
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Nicotinic Agonists/pharmacology
- Norepinephrine/blood
- Norepinephrine/metabolism
- Proto-Oncogene Proteins c-fos/genetics
- Proto-Oncogene Proteins c-fos/metabolism
- Rats, Sprague-Dawley
- Rats, Transgenic
- Rats, Wistar
- Receptors, Nicotinic/chemistry
- Receptors, Nicotinic/metabolism
- Synaptic Transmission/drug effects
- Wallerian Degeneration/complications
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Affiliation(s)
| | - Ellis Cooper
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Michael P Coleman
- The Babraham Institute, Babraham Research Campus, Babraham, Cambridge, United Kingdom; and
| | - Gerald J Taborsky
- Department of Medicine, University of Washington, Seattle, Washington; Veterans Affairs Puget Sound Health Care System, Seattle, Washington
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172
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Local axonal protection by WldS as revealed by conditional regulation of protein stability. Proc Natl Acad Sci U S A 2015. [PMID: 26209654 DOI: 10.1073/pnas.1508337112] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The expression of the mutant Wallerian degeneration slow (WldS) protein significantly delays axonal degeneration from various nerve injuries and in multiple species; however, the mechanism for its axonal protective property remains unclear. Although WldS is localized predominantly in the nucleus, it also is present in a smaller axonal pool, leading to conflicting models to account for the WldS fraction necessary for axonal protection. To identify where WldS activity is required to delay axonal degeneration, we adopted a method to alter the temporal expression of WldS protein in neurons by chemically regulating its protein stability. We demonstrate that continuous WldS activity in the axonal compartment is both necessary and sufficient to delay axonal degeneration. Furthermore, by specifically increasing axonal WldS expression postaxotomy, we reveal a critical period of 4-5 h postinjury during which the course of Wallerian axonal degeneration can be halted. Finally, we show that NAD(+), the metabolite of WldS/nicotinamide mononucleotide adenylyltransferase enzymatic activity, is sufficient and specific to confer WldS-like axon protection and is a likely molecular mediator of WldS axon protection. The results delineate a therapeutic window in which the course of Wallerian degeneration can be delayed even after injures have occurred and help narrow the molecular targets of WldS activity to events within the axonal compartment.
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173
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Ribchester RR. Some reminiscences on studies of age-dependent and activity-dependent degeneration of sensory and motor endings in mammalian skeletal muscle. J Anat 2015; 227:231-6. [PMID: 26179026 PMCID: PMC4523325 DOI: 10.1111/joa.12334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2015] [Indexed: 11/29/2022] Open
Abstract
I present here an overview of research on the biology of neuromuscular sensory and motor endings that was inspired and influenced partly by my educational experience in the Department of Zoology at the University of Durham, from 1971 to 1974. I allude briefly to neuromuscular synaptic structure and function in dystrophic mice, influences of activity on synapse elimination in development and regeneration, and activity-dependent protection and degeneration of neuromuscular junctions in WldS mice.
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Affiliation(s)
- Richard R Ribchester
- Euan MacDonald Centre for Motor Neurone Disease Research and Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh, UK
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174
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Gilley J, Orsomando G, Nascimento-Ferreira I, Coleman MP. Absence of SARM1 rescues development and survival of NMNAT2-deficient axons. Cell Rep 2015; 10:1974-81. [PMID: 25818290 PMCID: PMC4386025 DOI: 10.1016/j.celrep.2015.02.060] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/23/2014] [Accepted: 02/24/2015] [Indexed: 11/01/2022] Open
Abstract
SARM1 function and nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2) loss both promote axon degeneration, but their relative relationship in the process is unknown. Here, we show that NMNAT2 loss and resultant changes to NMNAT metabolites occur in injured SARM1-deficient axons despite their delayed degeneration and that axon degeneration specifically induced by NMNAT2 depletion requires SARM1. Strikingly, SARM1 deficiency also corrects axon outgrowth in mice lacking NMNAT2, independently of NMNAT metabolites, preventing perinatal lethality. Furthermore, NAMPT inhibition partially restores outgrowth of NMNAT2-deficient axons, suggesting that the NMNAT substrate, NMN, contributes to this phenotype. NMNAT2-depletion-dependent degeneration of established axons and restricted extension of developing axons are thus both SARM1 dependent, and SARM1 acts either downstream of NMNAT2 loss and NMN accumulation in a linear pathway or in a parallel branch of a convergent pathway. Understanding the pathway will help establish relationships with other modulators of axon survival and facilitate the development of effective therapies for axonopathies.
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Affiliation(s)
- Jonathan Gilley
- Signalling Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Giuseppe Orsomando
- Department of Clinical Sciences (DISCO), Section of Biochemistry, Polytechnic University of Marche, Via Ranieri 67, Ancona 60131, Italy
| | | | - Michael P Coleman
- Signalling Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
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175
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Brown R, Hynes-Allen A, Swan AJ, Dissanayake KN, Gillingwater TH, Ribchester RR. Activity-dependent degeneration of axotomized neuromuscular synapses in Wld S mice. Neuroscience 2015; 290:300-20. [PMID: 25617654 PMCID: PMC4362769 DOI: 10.1016/j.neuroscience.2015.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 01/10/2015] [Accepted: 01/12/2015] [Indexed: 12/12/2022]
Abstract
Use and disuse may influence synaptic maintenance but so far evidence for this has been indirect. We tested whether stimulation or disuse of neuromuscular junctions in adult WldS mice altered vulnerability to axotomy. Moderate activity optimized resistance to axotomy while disuse or stimulation increased the rate of synaptic degeneration.
Activity and disuse of synapses are thought to influence progression of several neurodegenerative diseases in which synaptic degeneration is an early sign. Here we tested whether stimulation or disuse renders neuromuscular synapses more or less vulnerable to degeneration, using axotomy as a robust trigger. We took advantage of the slow synaptic degeneration phenotype of axotomized neuromuscular junctions in flexor digitorum brevis (FDB) and deep lumbrical (DL) muscles of Wallerian degeneration-Slow (WldS) mutant mice. First, we maintained ex vivo FDB and DL nerve-muscle explants at 32 °C for up to 48 h. About 90% of fibers from WldS mice remained innervated, compared with about 36% in wild-type muscles at the 24-h checkpoint. Periodic high-frequency nerve stimulation (100 Hz: 1 s/100 s) reduced synaptic protection in WldS preparations by about 50%. This effect was abolished in reduced Ca2+ solutions. Next, we assayed FDB and DL innervation after 7 days of complete tetrodotoxin (TTX)-block of sciatic nerve conduction in vivo, followed by tibial nerve axotomy. Five days later, only about 9% of motor endplates remained innervated in the paralyzed muscles, compared with about 50% in 5 day-axotomized muscles from saline-control-treated WldS mice with no conditioning nerve block. Finally, we gave mice access to running wheels for up to 4 weeks prior to axotomy. Surprisingly, exercising WldS mice ad libitum for 4 weeks increased about twofold the amount of subsequent axotomy-induced synaptic degeneration. Together, the data suggest that vulnerability of mature neuromuscular synapses to axotomy, a potent neurodegenerative trigger, may be enhanced bimodally, either by disuse or by hyperactivity.
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Affiliation(s)
- R Brown
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - A Hynes-Allen
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - A J Swan
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - K N Dissanayake
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - T H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - R R Ribchester
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
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176
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Brown KD, Maqsood S, Huang JY, Pan Y, Harkcom W, Li W, Sauve A, Verdin E, Jaffrey SR. Activation of SIRT3 by the NAD⁺ precursor nicotinamide riboside protects from noise-induced hearing loss. Cell Metab 2014; 20:1059-68. [PMID: 25470550 PMCID: PMC4940130 DOI: 10.1016/j.cmet.2014.11.003] [Citation(s) in RCA: 214] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 09/08/2014] [Accepted: 11/04/2014] [Indexed: 12/20/2022]
Abstract
Intense noise exposure causes hearing loss by inducing degeneration of spiral ganglia neurites that innervate cochlear hair cells. Nicotinamide adenine dinucleotide (NAD(+)) exhibits axon-protective effects in cultured neurons; however, its ability to block degeneration in vivo has been difficult to establish due to its poor cell permeability and serum instability. Here, we describe a strategy to increase cochlear NAD(+) levels in mice by administering nicotinamide riboside (NR), a recently described NAD(+) precursor. We find that administration of NR, even after noise exposure, prevents noise-induced hearing loss (NIHL) and spiral ganglia neurite degeneration. These effects are mediated by the NAD(+)-dependent mitochondrial sirtuin, SIRT3, since SIRT3-overexpressing mice are resistant to NIHL and SIRT3 deletion abrogates the protective effects of NR and expression of NAD(+) biosynthetic enzymes. These findings reveal that administration of NR activates a NAD(+)-SIRT3 pathway that reduces neurite degeneration caused by noise exposure.
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Affiliation(s)
- Kevin D Brown
- Department of Otolaryngology-Head and Neck Surgery, Weill Medical College, Cornell University, New York, NY 10065, USA.
| | - Sadia Maqsood
- Department of Otolaryngology-Head and Neck Surgery, Weill Medical College, Cornell University, New York, NY 10065, USA
| | - Jing-Yi Huang
- Gladstone Institutes, University of California, San Francisco, San Francisco, CA 94941, USA
| | - Yong Pan
- Gladstone Institutes, University of California, San Francisco, San Francisco, CA 94941, USA
| | - William Harkcom
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY 10065, USA
| | - Wei Li
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY 10065, USA
| | - Anthony Sauve
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY 10065, USA
| | - Eric Verdin
- Gladstone Institutes, University of California, San Francisco, San Francisco, CA 94941, USA.
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY 10065, USA.
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177
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The axon-protective WLD(S) protein partially rescues mitochondrial respiration and glycolysis after axonal injury. J Mol Neurosci 2014; 55:865-71. [PMID: 25352062 PMCID: PMC4353883 DOI: 10.1007/s12031-014-0440-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 10/09/2014] [Indexed: 12/14/2022]
Abstract
The axon-protective Wallerian degeneration slow (WLDS) protein can ameliorate the decline in axonal ATP levels after neurite transection. Here, we tested the hypothesis that this effect is associated with maintenance of mitochondrial respiration and/or glycolysis. We used isolated neurites of superior cervical ganglion (SCG) cultures in the Seahorse XF-24 Metabolic Flux Analyser to determine mitochondrial respiration and glycolysis under different conditions. We observed that both mitochondrial respiration and glycolysis declined significantly during the latent phase of Wallerian degeneration. WLDS partially reduced the decline both in glycolysis and in mitochondrial respiration. In addition, we found that depleting NAD levels in uncut cultures led to changes in mitochondrial respiration and glycolysis similar to those rescued by WLDS after cut, suggesting that the maintenance of NAD levels in WldS neurites after axonal injury at least partially underlies the maintenance of ATP levels. However, by using another axon-protective mutation (Sarm1−/−), we could demonstrate that rescue of basal ECAR (and hence probably glycolysis) rather than basal OCR (mitochondrial respiration) may be part of the protective phenotype to delay Wallerian degeneration. These findings open new routes to study glycolysis and the connection between NAD and ATP levels in axon degeneration, which may help to eventually develop therapeutic strategies to treat neurodegenerative diseases.
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