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Tortosa E, Sengupta Ghosh A, Li Q, Wong WR, Hinkle T, Sandoval W, Rose CM, Hoogenraad CC. Stress-induced vesicular assemblies of dual leucine zipper kinase are signaling hubs involved in kinase activation and neurodegeneration. EMBO J 2022; 41:e110155. [PMID: 35611591 PMCID: PMC9289706 DOI: 10.15252/embj.2021110155] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 11/09/2022] Open
Abstract
Mitogen-activated protein kinases (MAPKs) drive key signaling cascades during neuronal survival and degeneration. The localization of kinases to specific subcellular compartments is a critical mechanism to locally control signaling activity and specificity upon stimulation. However, how MAPK signaling components tightly control their localization remains largely unknown. Here, we systematically analyzed the phosphorylation and membrane localization of all MAPKs expressed in dorsal root ganglia (DRG) neurons, under control and stress conditions. We found that MAP3K12/dual leucine zipper kinase (DLK) becomes phosphorylated and palmitoylated, and it is recruited to sphingomyelin-rich vesicles upon stress. Stress-induced DLK vesicle recruitment is essential for kinase activation; blocking DLK-membrane interaction inhibits downstream signaling, while DLK recruitment to ectopic subcellular structures is sufficient to induce kinase activation. We show that the localization of DLK to newly formed vesicles is essential for local signaling. Inhibition of membrane internalization blocks DLK activation and protects against neurodegeneration in DRG neurons. These data establish vesicular assemblies as dynamically regulated platforms for DLK signaling during neuronal stress responses.
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Affiliation(s)
- Elena Tortosa
- Department of Neuroscience, Genentech, Inc., South San Francisco, CA, USA
| | | | - Qingling Li
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., South San Francisco, CA, USA
| | - Weng Ruh Wong
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., South San Francisco, CA, USA
| | - Trent Hinkle
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., South San Francisco, CA, USA
| | - Wendy Sandoval
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., South San Francisco, CA, USA
| | - Christopher M Rose
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., South San Francisco, CA, USA
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Mercau ME, Patwa S, Bhat KPL, Ghosh S, Rothlin CV. Cell death in development, maintenance, and diseases of the nervous system. Semin Immunopathol 2022; 44:725-738. [PMID: 35508671 DOI: 10.1007/s00281-022-00938-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 04/12/2022] [Indexed: 02/07/2023]
Abstract
Cell death, be it of neurons or glial cells, marks the development of the nervous system. Albeit relatively less so than in tissues such as the gut, cell death is also a feature of nervous system homeostasis-especially in context of adult neurogenesis. Finally, cell death is commonplace in acute brain injuries, chronic neurodegenerative diseases, and in some central nervous system tumors such as glioblastoma. Recent studies are enumerating the various molecular modalities involved in the execution of cells. Intimately linked with cell death are mechanisms of disposal that remove the dead cell and bring about a tissue-level response. Heretofore, the association between these methods of dying and physiological or pathological responses has remained nebulous. It is envisioned that careful cartography of death and disposal may reveal novel understandings of disease states and chart new therapeutic strategies in the near future.
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Affiliation(s)
- Maria E Mercau
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, USA
| | - Siraj Patwa
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, USA
| | - Krishna P L Bhat
- Department of Translational Molecular Pathology, Division of Pathology-Lab Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Sourav Ghosh
- Department of Neurology, School of Medicine, Yale University, New Haven, CT, USA.,Department of Pharmacology, School of Medicine, Yale University, New Haven, CT, USA
| | - Carla V Rothlin
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, USA. .,Department of Pharmacology, School of Medicine, Yale University, New Haven, CT, USA.
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3
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Khaitin A. Calcium in Neuronal and Glial Response to Axotomy. Int J Mol Sci 2021; 22:ijms222413344. [PMID: 34948141 PMCID: PMC8706492 DOI: 10.3390/ijms222413344] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022] Open
Abstract
Neurotrauma assumes an instant or delayed disconnection of axons (axotomy), which affects not only neurons, but surrounding glia as well. Not only mechanically injured glia near the site of disconnection, especially transection, is subjected to the damage, but also glia that is remote from the lesion site. Glial cells, which surround the neuronal body, in turn, support neuron survival, so there is a mutual protection between neuron and glia. Calcium signaling is a central mediator of all post-axotomy events, both in neuron and glia, playing a critical role in their survival/regeneration or death/degeneration. The involvement of calcium in post-axotomy survival of the remote, mechanically intact glia is poorly studied. The purpose of this review is to sum up the calcium-involving mechanisms in responses of neurons and glial cells to axotomy to show their importance and to give some suggestions for future research of remote glia in this context.
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Affiliation(s)
- Andrey Khaitin
- Academy of Biology and Biotechnology, Southern Federal University, 344090 Rostov-on-Don, Russia
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4
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Bagaméry F, Varga K, Kecsmár K, Vincze I, Szökő É, Tábi T. The Impact of Differentiation on Cytotoxicity and Insulin Sensitivity in Streptozotocin Treated SH-SY5Y Cells. Neurochem Res 2021; 46:1350-1358. [PMID: 33616807 PMCID: PMC8084777 DOI: 10.1007/s11064-021-03269-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 02/01/2021] [Accepted: 02/05/2021] [Indexed: 11/29/2022]
Abstract
Recently neuronal insulin resistance was suggested playing a role in Alzheimer’s disease. Streptozotocin (STZ) is commonly used to induce impairment in insulin metabolism. In our previous work on undifferentiated SH-SY5Y cells the compound exerted cytotoxicity without altering insulin sensitivity. Nevertheless, differentiation of the cells to a more mature neuron-like phenotype may considerably affect the significance of insulin signaling and its sensitivity to STZ. We aimed at studying the influence of STZ treatment on insulin signaling in SH-SY5Y cells differentiated by retinoic acid (RA). Cytotoxicity of STZ or low serum (LS) condition and protective effect of insulin were compared in RA differentiated SH-SY5Y cells. The effect of insulin and an incretin analogue, exendin-4 on insulin signaling was also examined by assessing glycogen synthase kinase-3 (GSK-3) phosphorylation. STZ was found less cytotoxic in the differentiated cells compared to our previous results in undifferentiated SH-SY5Y cells. The cytoprotective concentration of insulin was similar in the STZ and LS groups. However, the right-shifted concentration–response curve of insulin induced GSK-3 phosphorylation in STZ-treated differentiated cells is suggestive of the development of insulin resistance that was further confirmed by the insulin potentiating effect of exendin-4. Differentiation reduced the sensitivity of SH-SY5Y cells for the non-specific cytotoxicity of STZ and enhanced the relative significance of development of insulin resistance. The differentiated cells thus serve as a better model for studying the role of insulin signaling in neuronal survival. However, direct cytotoxicity of STZ also contributes to the cell death.
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Affiliation(s)
- Fruzsina Bagaméry
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, 1089, Budapest, Hungary
| | - Kamilla Varga
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, 1089, Budapest, Hungary
| | - Kitti Kecsmár
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, 1089, Budapest, Hungary
| | - István Vincze
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, 1089, Budapest, Hungary
| | - Éva Szökő
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, 1089, Budapest, Hungary
| | - Tamás Tábi
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, 1089, Budapest, Hungary.
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5
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Alshamrani AA, Franklin JL. Membrane Depolarization Inhibits BIM EL Upregulation but Prevents Neuronal Apoptosis Primarily by Increasing Cellular GSH Levels. Mol Neurobiol 2021; 58:2284-2296. [PMID: 33417218 DOI: 10.1007/s12035-020-02234-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 11/25/2020] [Indexed: 11/24/2022]
Abstract
Sympathetic neurons deprived of nerve growth factor (NGF) die by apoptosis. Chronic depolarization with elevated concentrations of extracellular potassium ([K+]E) supports long-term survival of these and other types of neurons in culture. While depolarization has long been used to support neuronal cultures, little is known about the mechanism. We explored how chronic depolarization of NGF-deprived mouse sympathetic neurons in culture blocks apoptotic death. First, we determined the effects of elevated [K+]E on proapoptotic BH3-only proteins reported to be upregulated in sympathetic neurons after NGF withdrawal. Upregulation of BIMEL was blocked by depolarization while upregulation of PUMA was not. BMF levels did not increase after NGF withdrawal, and elevated [K+]E had no effect on its expression. dp5/HRK was not detectable. A large increase in production of mitochondria-derived reactive species (RS), including reactive oxygen species (ROS), occurs in NGF-deprived sympathetic neurons. Suppressing these RS prevents cytochrome c release from mitochondria and apoptosis. The addition of high [K+]E to cultures rapidly blocked increased RS and cytochrome c release. Elevated [K+]E caused an increase of the cellular antioxidant glutathione (GSH). Preventing this increase prevented the elevated [K+]E from blocking cytochrome c release and death. While suppression of BIMEL upregulation by elevated [K+]E may contribute to high [K+]E pro-survival effects, we conclude that elevated [K+]E prevents apoptotic death of NGF-deprived sympathetic neurons primarily via an antioxidant mechanism.
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Affiliation(s)
- Ali A Alshamrani
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA.,Department of Pharmacology and Toxicology, King Saud University, Riyadh, 11451, Saudi Arabia
| | - James L Franklin
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA.
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Neurotrophic effects of G M1 ganglioside, NGF, and FGF2 on canine dorsal root ganglia neurons in vitro. Sci Rep 2020; 10:5380. [PMID: 32214122 PMCID: PMC7096396 DOI: 10.1038/s41598-020-61852-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 03/04/2020] [Indexed: 01/26/2023] Open
Abstract
Dogs share many chronic morbidities with humans and thus represent a powerful model for translational research. In comparison to rodents, the canine ganglioside metabolism more closely resembles the human one. Gangliosides are components of the cell plasma membrane playing a role in neuronal development, intercellular communication and cellular differentiation. The present in vitro study aimed to characterize structural and functional changes induced by GM1 ganglioside (GM1) in canine dorsal root ganglia (DRG) neurons and interactions of GM1 with nerve growth factor (NGF) and fibroblast growth factor (FGF2) using immunofluorescence for several cellular proteins including neurofilaments, synaptophysin, and cleaved caspase 3, transmission electron microscopy, and electrophysiology. GM1 supplementation resulted in increased neurite outgrowth and neuronal survival. This was also observed in DRG neurons challenged with hypoxia mimicking neurodegenerative conditions due to disruptions of energy homeostasis. Immunofluorescence indicated an impact of GM1 on neurofilament phosphorylation, axonal transport, and synaptogenesis. An increased number of multivesicular bodies in GM1 treated neurons suggested metabolic changes. Electrophysiological changes induced by GM1 indicated an increased neuronal excitability. Summarized, GM1 has neurotrophic and neuroprotective effects on canine DRG neurons and induces functional changes. However, further studies are needed to clarify the therapeutic value of gangliosides in neurodegenerative diseases.
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7
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Bagaméry F, Varga K, Kecsmár K, Vincze I, Szökő É, Tábi T. Lack of insulin resistance in response to streptozotocin treatment in neuronal SH-SY5Y cell line. J Neural Transm (Vienna) 2019; 127:71-80. [PMID: 31858268 PMCID: PMC6942577 DOI: 10.1007/s00702-019-02118-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 12/08/2019] [Indexed: 12/20/2022]
Abstract
Recently, it is suggested that brain insulin resistance may contribute to the development of Alzheimer’s disease; therefore, there is a high interest in its investigation. Streptozotocin (STZ) is often used to induce dysregulation of glucose and insulin metabolism in animal and cell culture models. Alteration in insulin sensitivity however, has not yet been assessed in neuronal cells after STZ treatment. We aimed at studying the concentration dependence of the protective effect of insulin on STZ-induced damage using SH-SY5Y cell line. Cells were treated with STZ and cell viability was assessed by resazurin reduction and lactate dehydrogenase release assays. Low serum (LS) medium was used as control damage. The effect of various concentrations (30, 100, 300, 1000 nM) of insulin was studied on cell viability and glycogen synthase kinase-3 (GSK-3) phosphorylation, an indicator of insulin signaling. STZ induced dose- and time-dependent cytotoxicity, its 1 mM concentration exerted a low, gradually developing damage. The cytoprotective effect of insulin was demonstrated in both STZ and LS groups. Its maximal effect was lower in the STZ-treated cells; however, its effective concentration remained largely unaltered. Insulin-induced GSK-3 phosphorylation was similar in the STZ- and LS-treated cells suggesting unchanged insulin signaling. Our present results indicate that STZ does not induce significant impairment in insulin sensitivity in SH-SY5Y cells, thus in this cell line it is not a good tool for studying the role of insulin resistance in neurodegeneration and to examine protective agents acting by improving insulin signaling.
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Affiliation(s)
- Fruzsina Bagaméry
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Kamilla Varga
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Kitti Kecsmár
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - István Vincze
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Éva Szökő
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary
| | - Tamás Tábi
- Department of Pharmacodynamics, Semmelweis University, Nagyvárad tér 4, Budapest, 1089, Hungary.
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8
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Elrashidy RA, Liu G. Long-term diabetes causes molecular alterations related to fibrosis and apoptosis in rat urinary bladder. Exp Mol Pathol 2019; 111:104304. [PMID: 31479659 DOI: 10.1016/j.yexmp.2019.104304] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 07/23/2019] [Accepted: 08/30/2019] [Indexed: 02/05/2023]
Abstract
Diabetes induces time-dependent alterations in urinary bladders. Long-term diabetes causes an underactive bladder. However, the fundamental mechanisms are still elusive. This study aimed to examine the histological changes and the potential molecular pathways affected by long-term diabetes in the rat bladder. Diabetes was induced in 8-week-old male Lewis rats by streptozotocin, while age-matched control rats received citrate buffer only. Forty-four weeks after diabetes induction, bladders were harvested for histological and molecular analyses. The expressions of proteins related to fibrosis, apoptosis and oxidative stress as well as the cellular signaling pathway in the bladder were examined by immunoblotting. Histological examinations illustrated diabetes caused detrusor hypertrophy and fibrotic changes in the bladder. Immunoblotting analysis demonstrated higher collagen I but lower elastin expression in the bladder in diabetic rats. These were accompanied by an increase in the expression of transforming growth factor-beta1, along with the downregulation of matrix metalloptoteinase-1, and upregulation of tissue inhibitor of metalloproteinase-1. Diabetic rats showed an increase in nitrotyrosine, but decrease in nuclear factor erythroid-related factor 2 (Nrf2) levels in the bladder. Enhanced apoptotic signaling was observed, characterized by increased expression of Bcl-2-associated X protein (Bax), decreased expression of Bcl-2, in the diabetic bladder. The nerve growth factor level was decreased in the diabetic bladder. A significant suppression in the protein expressions of phosphorylated extracellular signal-regulated kinases 1/2 was found in diabetic bladders. This study demonstrated that long-term diabetes caused molecular changes that could promote fibrosis and apoptosis in the bladder. Oxidative stress may be involved in this context.
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Affiliation(s)
- Rania A Elrashidy
- Department of Surgery, MetroHealth Medical Center, Case Western Reserve University, Cleveland, OH, USA; Department of Biochemistry, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt
| | - Guiming Liu
- Department of Surgery, MetroHealth Medical Center, Case Western Reserve University, Cleveland, OH, USA.
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9
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Khamo JS, Krishnamurthy VV, Chen Q, Diao J, Zhang K. Optogenetic Delineation of Receptor Tyrosine Kinase Subcircuits in PC12 Cell Differentiation. Cell Chem Biol 2018; 26:400-410.e3. [PMID: 30595532 DOI: 10.1016/j.chembiol.2018.11.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 08/13/2018] [Accepted: 11/02/2018] [Indexed: 01/19/2023]
Abstract
Nerve growth factor elicits signaling outcomes by interacting with both its high-affinity receptor, TrkA, and its low-affinity receptor, p75NTR. Although these two receptors can regulate distinct cellular outcomes, they both activate the extracellular-signal-regulated kinase pathway upon nerve growth factor stimulation. To delineate TrkA subcircuits in PC12 cell differentiation, we developed an optogenetic system whereby light was used to specifically activate TrkA signaling in the absence of nerve growth factor. By using tyrosine mutants of the optogenetic TrkA in combination with pathway-specific pharmacological inhibition, we find that Y490 and Y785 each contributes to PC12 cell differentiation through the extracellular-signal-regulated kinase pathway in an additive manner. Optogenetic activation of TrkA eliminates the confounding effect of p75NTR and other potential off-target effects of the ligand. This approach can be generalized for the mechanistic study of other receptor-mediated signaling pathways.
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Affiliation(s)
- John S Khamo
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Vishnu V Krishnamurthy
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Qixin Chen
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
| | - Kai Zhang
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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10
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Geden MJ, Romero SE, Deshmukh M. Apoptosis versus axon pruning: Molecular intersection of two distinct pathways for axon degeneration. Neurosci Res 2018; 139:3-8. [PMID: 30452947 DOI: 10.1016/j.neures.2018.11.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Revised: 11/02/2018] [Accepted: 11/07/2018] [Indexed: 12/16/2022]
Abstract
Neurons are capable of degenerating their axons for the physiological clearance and refinement of unnecessary connections via the programmed degenerative pathways of apoptosis and axon pruning. While both pathways mediate axon degeneration they are however distinct. Whereas in apoptosis the entire neuron, both axons and cell body, degenerates, in the context of axon pruning only the targeted axon segments are selectively degenerated. Interestingly, the molecular pathways mediating axon degeneration in these two contexts have significant mechanistic overlap but also retain distinct differences. In this review, we describe the peripheral neuronal cell culture models used to study the molecular pathways of apoptosis and pruning. We outline what is known about the molecular mechanisms of apoptosis and axon pruning and focus on highlighting the similarities and differences of these two pathways.
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Affiliation(s)
- Matthew J Geden
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, 27599, USA; Neuroscience Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Selena E Romero
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, 27599, USA; Neuroscience Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Mohanish Deshmukh
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, 27599, USA; Neuroscience Center, University of North Carolina, Chapel Hill, NC, 27599, USA.
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11
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Donnelly CR, Gabreski NA, Suh EB, Chowdhury M, Pierchala BA. Non-canonical Ret signaling augments p75-mediated cell death in developing sympathetic neurons. J Cell Biol 2018; 217:3237-3253. [PMID: 30018091 PMCID: PMC6122988 DOI: 10.1083/jcb.201703120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 12/15/2017] [Accepted: 06/11/2018] [Indexed: 01/13/2023] Open
Abstract
Programmed cell death (PCD) is an evolutionarily conserved process critical in sculpting many organ systems, yet the underlying mechanisms remain poorly understood. Here, we investigated the interactions of pro-survival and pro-apoptotic receptors in PCD using the sympathetic nervous system as a model. We demonstrate that Ret, a receptor tyrosine kinase required for the survival of many neuronal populations, is restricted to a subset of degenerating neurons that rapidly undergo apoptosis. Pro-apoptotic conditions induce Ret to associate with the death receptor p75. Genetic deletion of p75 within Ret+ neurons, and deletion of Ret during PCD, inhibit apoptosis both in vitro and in vivo. Mechanistically, Ret inhibits nerve growth factor (NGF)-mediated survival of sympathetic neurons. Removal of Ret disrupts NGF-mediated TrkA ubiquitination, leading to increased cell surface levels of TrkA, thereby potentiating survival signaling. Additionally, Ret deletion significantly impairs p75 regulated intramembrane proteolysis cleavage, leading to reduced activation of downstream apoptotic effectors. Collectively, these results indicate that Ret acts non-canonically to augment p75-mediated apoptosis.
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Affiliation(s)
| | - Nicole A Gabreski
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI
| | - Esther B Suh
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI
| | - Monzurul Chowdhury
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI
| | - Brian A Pierchala
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI
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Long non-coding RNA and microRNA-675/let-7a mediates the protective effect of melatonin against early brain injury after subarachnoid hemorrhage via targeting TP53 and neural growth factor. Cell Death Dis 2018; 9:99. [PMID: 29367587 PMCID: PMC5833397 DOI: 10.1038/s41419-017-0155-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 12/25/2022]
Abstract
The objective of this study was to identify the protective effect of melatonin (MT) against early brain injury (EBI) following subarachnoid hemorrhage (SAH) and explore the underlying molecular mechanism. Real-time polymerase chain reaction (PCR) and luciferase assay were utilized to detect the effect of MT on H19 expression level, computation analysis and luciferase assay were conducted to the underlying mechanism of let-7a and miR-675. Real-time PCR, western blot analysis, immunohistochemistry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and flow cytometry analysis were performed to detect the effect of MT on H19, miR-675, let-7a, TP53, neural growth factor (NGF) levels, cell viability, and apoptosis status. Melatonin increased H19 expression level by enhancing H19 transcriptional efficiency in a concentration-dependent manner. MiR-675 and let-7a directly targeted P53 and NGF, respectively, and miR-675 reduced luciferase activity of wild-type but not mutant TP53 3′UTR. Meanwhile, let-7a suppressed luciferase activity of wild-type but not mutant NGF 3′UTR. H2O2 increased number of SA-b-gal, and while MT administration repressed the premature senescence. H2O2 obviously upregulated expressions of H19, miR-675, and NGF, and downregulated let-7a and TP53 levels; however, MT treatment reduced expressions of H19, miR-675, and NGF, and improved let-7a and TP53 levels. Treating with MT attenuated the neurological deficits and reduced the brain swelling. MT treatment repressed apoptosis of neurons caused by SAH. Levels of H19, miR-675, and NGF were much higher in the SAH + MT group, while there were even higher levels of H19, miR-675, and NGF in the SAH group than in the sham group; levels of let-7a and TP53 were much lower in the SAH + MT group, while they were even lower in the SAH group than in the sham group. Our study revealed that treatment with MT protected against EBI after SAH by modulating the signaling pathways of H19-miR-675-P53-apoptosis and H19-let-7a-NGF-apoptosis.
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13
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IL-17 Exerts Anti-Apoptotic Effect via miR-155-5p Downregulation in Experimental Autoimmune Encephalomyelitis. J Mol Neurosci 2017; 63:320-332. [PMID: 29063445 PMCID: PMC5696500 DOI: 10.1007/s12031-017-0981-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/26/2017] [Indexed: 11/13/2022]
Abstract
Multiple sclerosis is an autoimmune, neurodegenerative disease, affecting mostly young adults and resulting in progressive disability. It is a multifactorial disorder, with important involvement of both cellular and epigenetic components. Among the epigenetic factors, microRNAs are currently intensively investigated in the context of multiple sclerosis. It has been shown that their biogenesis and function may be regulated by various cytokines. IL-17, a hallmark cytokine of Th17 cells, has been thought to function predominantly as a pro-inflammatory factor, leading to increased disease symptoms. However, there are several studies indicating its protective role during inflammatory process. In this work, we have assessed the impact of high-dose IL-17 administration on microRNAs’ expression profile during the preclinical stage of EAE. For selected microRNA, we have performed computational analysis of its potential target mRNAs and cellular pathways. Based on results obtained from in silico analysis, we have chosen genes from neurotrophin signaling pathway for further experiments—BDNF, HRAS, and BCL2. Results obtained in this study suggested that high dose of IL-17 exerts protective activity via miR-155-5p downregulation. Increased expression of all studied genes, especially BCL2, indicated a potential anti-apoptotic function of IL-17 during the preclinical phase of EAE.
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14
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PROneurotrophins and CONSequences. Mol Neurobiol 2017; 55:2934-2951. [DOI: 10.1007/s12035-017-0505-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/21/2017] [Indexed: 01/12/2023]
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15
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Yu L, Wang M, Hu D, Huang B, Zhou L, Zhou X, Wang Z, Wang S, Jiang H. Blocking the Nav1.8 channel in the left stellate ganglion suppresses ventricular arrhythmia induced by acute ischemia in a canine model. Sci Rep 2017; 7:534. [PMID: 28373696 PMCID: PMC5428783 DOI: 10.1038/s41598-017-00642-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 03/07/2017] [Indexed: 01/01/2023] Open
Abstract
Left stellate ganglion (LSG) hyperactivity promotes ischemia induced ventricular arrhythmia (VA). Blocking the Nav1.8 channel decreases neuron activity. Therefore, the present study aimed to investigate whether blocking the Nav1.8 channel with its specific blocker A-803467 in the LSG reduces sympathetic activity and exerts anti-arrhythmic effects. Forty canines were divided into dimethylsulfoxide (DMSO) group and 10 mM, 15 mM, and 20 mM A-803467 groups. A volume of 0.1 ml of A-803467 or DMSO was injected into the LSG. The ventricular electrophysiological parameters, LSG function were measured before and 30 min after the injection. VA was assessed for 60 min after ischemia and then LSG tissues were collected for molecular biological experiments. Compared with DMSO, concentration-dependent prolonged action potential duration and effective refractory period, decreased LSG function were identified after A-803467 treatment. Moreover, the severity of ischemia induced VA was decreased in A-803467 groups. Furthermore, decreased nerve growth factor, decreased c-fos and increased sympathetic neuron apoptosis were found in the LSG after A-803467 injection. In conclusion, blocking the Nav1.8 channel could significantly attenuate ischemia-induced VA, primarily by suppressing LSG activity.
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Affiliation(s)
- Lilei Yu
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Menglong Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Dan Hu
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China.,Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, New York, 13501-1787, USA
| | - Bing Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Liping Zhou
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Xiaoya Zhou
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Zhuo Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Songyun Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Hong Jiang
- Department of Cardiology, Renmin Hospital of Wuhan University, Cardiovascular Research Institute, Wuhan University, Hubei Key Laboratory of Cardiology, Wuhan, China.
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16
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N-Propargyl Caffeamide (PACA) Ameliorates Dopaminergic Neuronal Loss and Motor Dysfunctions in MPTP Mouse Model of Parkinson's Disease and in MPP +-Induced Neurons via Promoting the Conversion of proNGF to NGF. Mol Neurobiol 2017; 55:2258-2267. [PMID: 28321769 DOI: 10.1007/s12035-017-0486-6] [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: 11/20/2016] [Accepted: 03/09/2017] [Indexed: 10/19/2022]
Abstract
Insufficient production of nerve growth factor (NGF) is implicated in Parkinson's disease (PD). We recently discovered that caffeic acid derivative N-propargyl caffeamide (PACA) not only potentiated NGF-induced neurite outgrowth but also attenuated 6-hydroxydopamine neurotoxicity in neuronal culture. The aim of the present study was to investigate whether PACA could increase NGF levels against 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) neurotoxicity in a mouse PD model. We induced parkinsonism in mice by intraperitoneal injection of MPTP for seven consecutive days. Animal motor functions were assessed by rotarod test and pole test. Our results showed that PACA ameliorated motor impairments in MPTP-challenged mice. Based on Western blot analysis and/or immunofluorescence staining of NGF and tyrosine hydroxylase (TH), PACA preserved TH levels in the midbrain substantia nigra pars compacta. PACA also increased NGF expression while it decreased proNGF accumulation. Interestingly, NGF was widely induced in the midbrains including astrocytes. To elucidate the mechanisms by which PACA induces NGF, we focused on the effects of PACA on two neurotrophic signaling pathways, the PI3K and MEK pathways. We found that PACA induced the phosphorylation of Akt, ERK, and CREB against MPTP-mediated alterations. Importantly, PACA increased NGF levels and subsequently induced TrkA activation in MPTP-treated mice. Consistently, PACA also increased NGF levels in dopaminergic PC12 cells and primary rat midbrain neurons against N-methyl-4-phenylpyridinium iodide (MPP+) toxicity. ERK and PI3K inhibitors attenuated the effects of PACA on NGF levels. Collectively, our results suggest that PACA may rescue NGF insufficiency via sequential activation of PI3K/Akt, ERK1/2, and CREB signaling pathways. Graphical Abstract ᅟ.
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Mariga A, Mitre M, Chao MV. Consequences of brain-derived neurotrophic factor withdrawal in CNS neurons and implications in disease. Neurobiol Dis 2017; 97:73-79. [PMID: 27015693 PMCID: PMC5295364 DOI: 10.1016/j.nbd.2016.03.009] [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] [Received: 11/23/2015] [Revised: 02/20/2016] [Accepted: 03/09/2016] [Indexed: 01/07/2023] Open
Abstract
Growth factor withdrawal has been studied across different species and has been shown to have dramatic consequences on cell survival. In the nervous system, withdrawal of nerve growth factor (NGF) from sympathetic and sensory neurons results in substantial neuronal cell death, signifying a requirement for NGF for the survival of neurons in the peripheral nervous system (PNS). In contrast to the PNS, withdrawal of central nervous system (CNS) enriched brain-derived neurotrophic factor (BDNF) has little effect on cell survival but is indispensible for synaptic plasticity. Given that most early events in neuropsychiatric disorders are marked by a loss of synapses, lack of BDNF may thus be an important part of a cascade of events that leads to neuronal degeneration. Here we review reports on the effects of BDNF withdrawal on CNS neurons and discuss the relevance of the loss in disease.
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Affiliation(s)
- Abigail Mariga
- Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, United States; Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, United States
| | - Mariela Mitre
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, 10016, United States; Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, United States
| | - Moses V Chao
- Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, United States; Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, 10016, United States; Department of Psychiatry, New York University School of Medicine, New York, NY, 10016, United States; Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, United States
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18
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Sharma V, Thakur V, Singh SN, Guleria R. Tumor Necrosis Factor and Alzheimer's Disease: A Cause and Consequence Relationship. ACTA ACUST UNITED AC 2016. [DOI: 10.5455/bcp.20120112064639] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Vivek Sharma
- Government College of Pharmacy, Rohru, Distt. Shimla-171207, Himachal Pradesh, India
| | - Vinay Thakur
- Government College of Pharmacy, Rohru, Distt. Shimla-171207, Himachal Pradesh, India
| | - Shesh Nath Singh
- Government College of Pharmacy, Rohru, Distt. Shimla-171207, Himachal Pradesh, India
| | - Rajender Guleria
- Government College of Pharmacy, Rohru, Distt. Shimla-171207, Himachal Pradesh, India
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19
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Lim CH, Zainal NZ, Kanagasundram S, Zain SM, Mohamed Z. Preliminary examination of microRNA expression profiling in bipolar disorder I patients during antipsychotic treatment. Am J Med Genet B Neuropsychiatr Genet 2016; 171:867-74. [PMID: 27177356 DOI: 10.1002/ajmg.b.32457] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/02/2016] [Indexed: 02/01/2023]
Abstract
Although major progress has been achieved in research and development of antipsychotic medications for bipolar disorder (BPD), knowledge of the molecular mechanisms underlying this disorder and the action of atypical antipsychotics remains incomplete. The levels of microRNAs (miRNAs)-small non-coding RNA molecules that regulate gene expression, including genes involved in neuronal function and plasticity-are frequently altered in psychiatric disorders. This study aimed to examine changes in miRNA expression in bipolar mania patients after treatment with asenapine and risperidone. Using a miRNA microarray, we analyzed miRNA expression in the blood of 10 bipolar mania patients following 12 weeks of treatment with asenapine or risperidone. Selected miRNAs were validated by using real-time PCR. A total of 16 miRNAs were differentially expressed after treatment in the asenapine group, 14 of which were significantly upregulated and the other two significantly downregulated. However, all three differentially expressed miRNAs in the risperidone group were downregulated. MiRNA target gene prediction and gene ontology analysis revealed significant enrichment for pathways associated with immune system response and regulation of programmed cell death and transcription. Our results suggest that candidate miRNAs may be involved in the mechanism of action of both antipsychotics in bipolar mania. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Chor Hong Lim
- The Pharmacogenomics Laboratory, Faculty of Medicine, Department of Pharmacology, University of Malaya, Kuala Lumpur, Malaysia
| | - Nor Zuraida Zainal
- Faculty of Medicine, Department of Psychological Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Sharmilla Kanagasundram
- Faculty of Medicine, Department of Psychological Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Shamsul Mohd Zain
- The Pharmacogenomics Laboratory, Faculty of Medicine, Department of Pharmacology, University of Malaya, Kuala Lumpur, Malaysia
| | - Zahurin Mohamed
- The Pharmacogenomics Laboratory, Faculty of Medicine, Department of Pharmacology, University of Malaya, Kuala Lumpur, Malaysia
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20
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Mitochondria-derived reactive oxygen species mediate caspase-dependent and -independent neuronal deaths. Mol Cell Neurosci 2014; 63:13-23. [PMID: 25239010 DOI: 10.1016/j.mcn.2014.09.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 09/03/2014] [Accepted: 09/12/2014] [Indexed: 01/04/2023] Open
Abstract
Mitochondrial dysfunction and oxidative stress are implicated in many neurodegenerative diseases. Mitochondria-targeted drugs that effectively decrease oxidative stress, protect mitochondrial energetics, and prevent neuronal loss may therefore lend therapeutic benefit to these currently incurable diseases. To investigate the efficacy of such drugs, we examined the effects of mitochondria-targeted antioxidants MitoQ10 and MitoE2 on neuronal death induced by neurotrophin deficiency. Our results indicate that MitoQ10 blocked apoptosis by preventing increased mitochondria-derived reactive oxygen species (ROS) and subsequent cytochrome c release, caspase activation, and mitochondrial damage in nerve growth factor (NGF)-deprived sympathetic neurons, while MitoE2 was largely ineffective. In this paradigm, the most proximal point of divergence was the ability of MitoQ10 to scavenge mitochondrial superoxide (O2(-)). MitoQ10 also prevented caspase-independent neuronal death in these cells demonstrating that the mitochondrial redox state significantly influences both apoptotic and nonapoptotic pathways leading to neuronal death. We suggest that mitochondria-targeted antioxidants may provide tools for delineating the role and significance of mitochondrial ROS in neuronal death and provide a new therapeutic approach for neurodegenerative conditions involving trophic factor deficits and multiple modes of cell death.
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21
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Mariga A, Zavadil J, Ginsberg SD, Chao MV. Withdrawal of BDNF from hippocampal cultures leads to changes in genes involved in synaptic function. Dev Neurobiol 2014; 75:173-92. [PMID: 25059794 DOI: 10.1002/dneu.22216] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 06/26/2014] [Accepted: 07/23/2014] [Indexed: 11/07/2022]
Abstract
Neurotrophins play a crucial role in mediating neuronal survival and synaptic plasticity. A lack of trophic factor support in the peripheral nervous system (PNS) is associated with a transcription-dependent programmed cell death process in developing sympathetic neurons. While most of the attention has been on events culminating in cell death in the PNS, the earliest events that occur after trophic factor withdrawal in the central nervous system (CNS) have not been investigated. In the CNS, brain-derived neurotrophic factor (BDNF) is widely expressed and is released in an activity-dependent manner to shape the structure and function of neuronal populations. Reduced neurotrophic factor support has been proposed as a mechanism to account for changes in synaptic plasticity during neurodevelopment to aging and neurodegenerative disorders. To this end, we performed transcriptional profiling in cultured rat hippocampal neurons. We used a TrkB ligand scavenger (TrkB-FC ) to sequester endogenous neurotrophic factor activity from hippocampal neurons in culture. Using a high-density microarray platform, we identified a significant decrease in genes that are associated with vesicular trafficking and synaptic function, as well as selective increases in MAP kinase phosphatases. A comparison of these changes with recent studies of Alzheimer's disease and cognitive impairment in postmortem brain tissue revealed striking similarities in gene expression changes for genes involved in synaptic function. These changes are relevant to a wide number of conditions in which levels of BDNF are compromised.
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Affiliation(s)
- Abigail Mariga
- Cell and Molecular Biology Program, New York University Langone Medical Center, New York, New York, 10016
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22
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Nerve growth factor-mediated inhibition of apoptosis post-caspase activation is due to removal of active caspase-3 in a lysosome-dependent manner. Cell Death Dis 2014; 5:e1202. [PMID: 24787014 PMCID: PMC4047888 DOI: 10.1038/cddis.2014.173] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 02/18/2014] [Accepted: 02/19/2014] [Indexed: 12/15/2022]
Abstract
Nerve growth factor (NGF) is well characterised as an important pro-survival factor in neuronal cells that can inhibit apoptotic cell death upstream of mitochondrial outer membrane permeabilisation. Here we addressed the question of whether NGF can also protect against apoptosis downstream of caspase activation. NGF treatment promoted a rapid reduction in the level of the p17 subunit of active caspase-3 in PC12 cells that had been induced to undergo apoptosis by various cytotoxins. The mechanism involved TrkA-dependent activation of extracellular signal-regulated kinase (ERK1/2) but not phosphatidylinositol 3-kinase (PI3K)/Akt, and de novo protein synthesis. Involvement of inhibitor of apoptosis proteins (IAPs) and proteasomal degradation were ruled out. In contrast, inhibition of lysosome function using chloroquine and concanamycin A reversed NGF-induced removal of p17. Moreover, in NGF-treated cells, active caspases were found to be localised to lysosomes. The involvement of macroautophagy and chaperone-mediated autophagy were ruled out. Taken together, these findings suggest an anti-apoptotic mechanism by which NGF induces removal of active caspase-3 in a lysosome-dependent manner.
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23
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Sokolowski JD, Gamage KK, Heffron DS, LeBlanc AC, Deppmann CD, Mandell JW. Caspase-mediated cleavage of actin and tubulin is a common feature and sensitive marker of axonal degeneration in neural development and injury. Acta Neuropathol Commun 2014; 2:16. [PMID: 24507707 PMCID: PMC3996144 DOI: 10.1186/2051-5960-2-16] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/05/2014] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Axon degeneration is a characteristic feature of multiple neuropathologic states and is also a mechanism of physiological neurodevelopmental pruning. The vast majority of in vivo studies looking at axon degeneration have relied on the use of classical silver degeneration stains, which have many limitations including lack of molecular specificity and incompatibility with immunolabeling methods. Because Wallerian degeneration is well known to involve cytoskeletal disassembly and because caspases are recently implicated in aspects of this process, we asked whether antibodies directed at caspase-generated neoepitopes of beta-actin and alpha-tubulin would be useful immunohistochemical markers of pathological and developmental axon degeneration. RESULTS Here we demonstrate that several forms of axon degeneration involve caspase-mediated cleavage of these cytoskeletal elements and are well-visualized using this approach. We demonstrate the generation of caspase-induced neoepitopes in a) an in vitro neuronal culture model using nerve growth factor-deprivation-induced degeneration and b) an in vivo model using ethanol-induced neuronal apoptosis, and c) during normal developmental pruning and physiological turnover of neurons. CONCLUSIONS Our findings support recent experimental data that suggests caspase-3 and caspase-6 have specific non-redundant roles in developmental pruning. Finally, these findings may have clinical utility, as these markers highlight degenerating neurites in human hypoxic-ischemic injury. Our work not only confirms a common downstream mechanism involved in axon degeneration, but also illuminates the potential utility of caspase-cleavage-neoepitope antibodies as markers of neurodegeneration.
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Coulibaly AP, Gannon SM, Hawk K, Walsh BF, Isaacson LG. Transection of preganglionic axons leads to CNS neuronal plasticity followed by survival and target reinnervation. Auton Neurosci 2013; 179:49-59. [PMID: 23891533 DOI: 10.1016/j.autneu.2013.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 06/17/2013] [Accepted: 07/04/2013] [Indexed: 10/26/2022]
Abstract
The goals of the present study were to investigate the changes in sympathetic preganglionic neurons following transection of distal axons in the cervical sympathetic trunk (CST) that innervate the superior cervical ganglion (SCG) and to assess changes in the protein expression of brain derived neurotrophic factor (BDNF) and its receptor TrkB in the thoracic spinal cord. At 1 week, a significant decrease in soma volume and reduced soma expression of choline acetyltransferase (ChAT) in the intermediolateral cell column (IML) of T1 spinal cord were observed, with both ChAT-ir and non-immunoreactive neurons expressing the injury marker activating transcription factor 3. These changes were transient, and at later time points, ChAT expression and soma volume returned to control values and the number of ATF3 neurons declined. No evidence for cell loss or neuronal apoptosis was detected at any time point. Protein levels of BDNF and/or full length TrkB in the spinal cord were increased throughout the survival period. In the SCG, both ChAT-ir axons and ChAT protein remained decreased at 16 weeks, but were increased compared to the 10 week time point. These results suggest that though IML neurons show reduced ChAT expression and cell volume at 1 week following CST transection, at later time points, the neurons recovered and exhibited no significant signs of neurodegeneration. The alterations in BDNF and/or TrkB may have contributed to the survival of the IML neurons and the recovery of ChAT expression, as well as to the reinnervation of the SCG.
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Affiliation(s)
- Aminata P Coulibaly
- Center for Neuroscience and Behavior, Miami University, Oxford, OH 45056, United States; Graduate Program in Cell, Molecular, and Structural Biology, Miami University, Oxford, OH 45056, United States
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25
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Abstract
Neurons completely transform how they regulate cell death over the course of their lifetimes. Developing neurons freely activate cell death pathways to fine-tune the number of neurons that are needed during the precise formation of neural networks. However, the regulatory balance between life and death shifts as neurons mature beyond early development. Mature neurons promote survival at all costs by employing multiple, often redundant, strategies to prevent cell death by apoptosis. This dramatic shift from permitting cell death to ensuring cellular survival is critical, as these post-mitotic cells must provide neuronal circuitry for an organism's entire lifetime. Importantly, as many neurodegenerative diseases afflict adult neuronal populations, the survival mechanisms in mature neurons are likely to be either reversed or circumvented during neurodegeneration. Examining the adaptations for inhibiting apoptosis during neuronal maturation is key to comprehending not just how neurons survive long term, but may also provide insight for understanding how neuronal toxicity in various neurodegenerative diseases may ultimately lead to cell death.
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Affiliation(s)
- A J Kole
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
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26
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Carballeira NM. Recent developments in the antiprotozoal and anticancer activities of the 2-alkynoic fatty acids. Chem Phys Lipids 2013; 172-173:58-66. [PMID: 23727443 DOI: 10.1016/j.chemphyslip.2013.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 12/21/2022]
Abstract
The 2-alkynoic fatty acids are an interesting group of synthetic compounds that display antimycobacterial, antifungal, anticancer, and pesticidal activities but their antiprotozoal activity has received little attention until recently. In this review we have summarized our present knowledge of the biomedical potential of the 2-hexadecynoic acid (2-HDA) and 2-octadecynoic acid (2-ODA) together with several mechanistic pieces of work attesting to the fact that these compounds, and their metabolites, are good fatty acid biosynthesis inhibitors. The antiprotozoal activity of 2-HDA and 2-ODA against Leishmania donovani and Plasmodium falciparum, parasites responsible for visceral leishmaniasis and malaria, respectively, is also reviewed. The evidence obtained so far supports the fact that these fatty acids are good inhibitors of the L. donovani DNA topoisomerase IB enzyme (LdTopIB) and the potency of LdTopIB inhibition is chain length dependent. We also demonstrate the generality of the antiprotozoal activity of 2-HDA and 2-ODA against P. falciparum, and review our present knowledge of their inhibition of key P. falciparum enzymes such as PfFabZ, PfFabG, and PfFabI together with some possible modes of inhibition. Recent research by our group has also demonstrated that 2-ODA displays antineoplastic activity, specifically against the neuroblastoma SH-SY5Y cell line via lactate dehydrogenase (LDH) release, which is a cell death mechanism principally associated to necrosis. This is the first comprehensive review of the medicinal chemistry of this interesting group of acetylenic fatty acids.
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Affiliation(s)
- Néstor M Carballeira
- Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, PO Box 23346, San Juan 00931-3346, Puerto Rico.
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The role of glucocorticoid receptors in dexamethasone-induced apoptosis of neuroprogenitor cells in the hippocampus of rat pups. Mediators Inflamm 2013; 2013:628094. [PMID: 23401645 PMCID: PMC3557631 DOI: 10.1155/2013/628094] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 12/17/2012] [Indexed: 12/25/2022] Open
Abstract
Background. Dexamethasone (Dex) has been used to reduce inflammation in preterm infants with assistive ventilation and to prevent chronic lung diseases. However, Dex treatment results in adverse effects on the brain. Since the hippocampus contains a high density of glucocorticoid receptors (GCRs), we hypothesized that Dex affects neurogenesis in the hippocampus through inflammatory mediators. Methods. Albino Wistar rat pups first received a single dose of Dex (0.5 mg/kg) on postnatal day 1 (P1) and were sacrificed on P2, P3, P5, and P7. One group of Dex-treated pups (Dex-treated D1D2) was given mifepristone (RU486, a GCR antagonist) on P1 and sacrificed on P2. Hippocampi were isolated for western blot analysis, TUNEL, cleaved-caspase 3 staining for cell counts, and morphological assessment. Control pups received normal saline (NS). Results. Dex reduced the developmental gain in body weight, but had no effect on brain weight. In the Dex-treated D1D2 group, apoptotic cells increased in number based on TUNEL and cleaved-caspase 3 staining. Most of the apoptotic cells expressed the neural progenitor cell marker nestin. Dex-induced apoptosis in P1 pups was markedly reduced (60%) by pretreatment with RU486, indicating the involvement of GCRs. Conclusion. Early administration of Dex results in apoptosis of neural progenitor cells in the hippocampus and this is mediated through GCRs.
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28
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Ambacher KK, Pitzul KB, Karajgikar M, Hamilton A, Ferguson SS, Cregan SP. The JNK- and AKT/GSK3β- signaling pathways converge to regulate Puma induction and neuronal apoptosis induced by trophic factor deprivation. PLoS One 2012; 7:e46885. [PMID: 23056511 PMCID: PMC3463558 DOI: 10.1371/journal.pone.0046885] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 09/07/2012] [Indexed: 12/17/2022] Open
Abstract
The AKT, GSK3 and JNK family kinases have been implicated in neuronal apoptosis associated with neuronal development and several neurodegenerative conditions. However, the mechanisms by which these kinase pathways regulate apoptosis remain unclear. In this study we have investigated the role of these kinases in neuronal cell death using an established model of trophic factor deprivation induced apoptosis in cerebellar granule neurons. BCL-2 family proteins are known to be central regulators of apoptosis and we have determined that the pro-apoptotic family member Puma is transcriptionally up-regulated in trophic factor deprived neurons and that Puma induction is required for apoptosis in vitro and in vivo. Importantly, we demonstrate that Puma induction is dependent on both JNK activation and AKT inactivation. AKT is known to regulate a number of downstream pathways, however we have determined that PI3K-AKT inactivation induces Puma expression through a GSK3β-dependent mechanism. Finally we demonstrate that the JNK and AKT/GSK3β pathways converge to regulate FoxO3a-mediated transcriptional activation of Puma. In summary we have identified a novel and critical link between the AKT, GSK3β and JNK kinases and the regulation of Puma induction and suggest that this may be pivotal to the regulation of neuronal apoptosis in neurodegenerative conditions.
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Affiliation(s)
- Kristin K. Ambacher
- Robarts Research Institute and Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Kristen B. Pitzul
- Robarts Research Institute and Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Meera Karajgikar
- Robarts Research Institute and Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Alison Hamilton
- Robarts Research Institute and Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Stephen S. Ferguson
- Robarts Research Institute and Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Sean P. Cregan
- Robarts Research Institute and Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
- * E-mail:
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Chalazonitis A, Gershon MD, Greene LA. Cell death and the developing enteric nervous system. Neurochem Int 2012; 61:839-47. [PMID: 22342822 DOI: 10.1016/j.neuint.2012.01.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 01/25/2012] [Accepted: 01/27/2012] [Indexed: 12/16/2022]
Abstract
This review discusses current knowledge about cell death in the developing enteric nervous system (ENS). It also includes findings about the molecular mechanisms by which such death is mediated. Additional consideration is given to trophic factors that contribute to survival of the precursors and neurons and glia of the ENS, as well to genes that, when mutated or deleted, trigger their death. Although further confirmation is needed, present observations support the view that enteric neural crest-derived precursor cells en route to the gut undergo substantial levels of apoptotic death, but that once these cells colonize the gut, there is relatively little death of precursor cells or of neurons and glia during the fetal period. There are also indications that normal neuron loss occurs in the ENS, but at times beyond the perinatal stage. Taken together, these findings suggest that ENS development is similar is some ways, but different in others from extra-enteric areas of the vertebrate central and peripheral nervous systems, in which large-scale apoptotic death of precursor neurons and glia occurs during the fetal and perinatal periods. Potential reasons for these differences are discussed such as a fetal enteric microenvironment that is especially rich in trophic support. In addition to the cell death that occurs during normal ENS development, this review discusses mechanisms of experimentally-induced ENS cell death, such as those that are associated with defective glial cell-line derived neurotrophic factor/Ret signaling, which are an animal model of human congenital megacolon (aganglionosis; Hirschsprung's disease). Such considerations underscore the importance of understanding cell death in the developing ENS, not just from a curiosity-driven point of view, but also because the pathophysiology behind many disorders of human gastrointestinal function may originate in abnormalities of the mechanisms that govern cell survival and death during ENS development.
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Affiliation(s)
- Alcmène Chalazonitis
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA.
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Hughes R, Kristiansen M, Lassot I, Desagher S, Mantovani R, Ham J. NF-Y is essential for expression of the proapoptotic bim gene in sympathetic neurons. Cell Death Differ 2010; 18:937-47. [PMID: 21164521 DOI: 10.1038/cdd.2010.166] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Neuronal apoptosis has a major role during development and aberrant apoptosis contributes to the pathology of certain neurological conditions. Studies with nerve growth factor (NGF)-dependent sympathetic neurons have provided important insights into the molecular mechanisms of neuronal apoptosis and the signalling pathways that regulate the cell death programme in neurons. The BH3-only protein Bim is a critical mediator of apoptosis in many cell types and in sympathetic neurons is required for NGF withdrawal-induced death. However, regulation of bim expression is complex and remains incompletely understood. We report that a conserved inverted CCAAT box (ICB) in the rat bim promoter is bound by the heterotrimeric transcription factor NF-Y. Interestingly, NF-Y is required for bim promoter activity and its induction following NGF withdrawal. We demonstrate that NF-Y activity is essential for endogenous Bim expression and contributes to NGF withdrawal-induced death. Furthermore, we find that the transcriptional coactivators CBP and p300 interact with NF-Y and FOXO3a and bind to this region of the bim promoter. The amount of CBP/p300 bound to bim increases after NGF deprivation and inhibition of CBP/p300 activity reduces bim induction. Our results indicate that NF-Y cooperates with FOXO3a to recruit CBP/p300 to the bim promoter to form a stable multi-protein/DNA complex that activates bim transcription after survival factor withdrawal.
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Affiliation(s)
- R Hughes
- Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, London, UK
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Golbs A, Nimmervoll B, Sun JJ, Sava IE, Luhmann HJ. Control of programmed cell death by distinct electrical activity patterns. Cereb Cortex 2010; 21:1192-202. [PMID: 20966045 DOI: 10.1093/cercor/bhq200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Electrical activity and sufficient supply with survival factors play a major role in the control of apoptosis in the developing cortex. Coherent high-frequency neuronal activity, which efficiently releases neurotrophins, is essential for the survival of immature neurons. We studied the influence of neuronal activity on apoptosis in the developing cortex. Dissociated cultures of the newborn mouse cerebral cortex were grown on multielectrode arrays to determine the activity patterns that promote neuronal survival. Cultures were transfected with a plasmid coding for a caspase-3-sensitive fluorescent protein allowing real-time analysis of caspase-3-dependent apoptosis in individual neurons. Elevated extracellular potassium concentrations (5 and 8 mM), application of 4-aminopyridine or the γ-aminobutyric acid-A receptor antagonist Gabazine induced a shift in the frequency distribution of activity toward high-frequency bursts. Under these conditions, a reduction or delay in caspase-3 activation and an overall increase in neuronal survival could be observed. This effect was dependent on the activity of phosphatidylinositol-3 kinase, as blockade of this enzyme abolished the survival-promoting effect of high extracellular potassium concentrations. Our data indicate that increased network activity can prevent apoptosis in developing cortical neurons.
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Affiliation(s)
- Antje Golbs
- Institute of Physiology and Pathophysiology, University Medical Center, Johannes Gutenberg University, D-55128 Mainz, Germany
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Sheline CT, Cai AL, Zhu J, Shi C. Serum or target deprivation-induced neuronal death causes oxidative neuronal accumulation of Zn2+ and loss of NAD+. Eur J Neurosci 2010; 32:894-904. [PMID: 20722716 DOI: 10.1111/j.1460-9568.2010.07372.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Trophic deprivation-mediated neuronal death is important during development, after acute brain or nerve trauma, and in neurodegeneration. Serum deprivation (SD) approximates trophic deprivation in vitro, and an in vivo model is provided by neuronal death in the mouse dorsal lateral geniculate nucleus (LGNd) after ablation of the visual cortex (VCA). Oxidant-induced intracellular Zn(2+) release ([Zn(2+) ](i) ) from metallothionein-3 (MT-III), mitochondria or 'protein Zn(2+) ', was implicated in trophic deprivation neurotoxicity. We have previously shown that neurotoxicity of extracellular Zn(2+) required entry, increased [Zn(2+) ](i) , and reduction of NAD(+) and ATP levels causing inhibition of glycolysis and cellular metabolism. Exogenous NAD(+) and sirtuin inhibition attenuated Zn(2+) neurotoxicity. Here we show that: (1) Zn(2+) is released intracellularly after oxidant and SD injuries, and that sensitivity to these injuries is proportional to neuronal Zn(2+) content; (2) NAD(+) loss is involved - restoration of NAD(+) using exogenous NAD(+) , pyruvate or nicotinamide attenuated these injuries, and potentiation of NAD(+) loss potentiated injury; (3) neurons from genetically modified mouse strains which reduce intracellular Zn(2+) content (MT-III knockout), reduce NAD(+) catabolism (PARP-1 knockout) or increase expression of an NAD(+) synthetic enzyme (Wld(s) ) each had attenuated SD and oxidant neurotoxicities; (4) sirtuin inhibitors attenuated and sirtuin activators potentiated these neurotoxicities; (5) visual cortex ablation (VCA) induces Zn(2+) staining and death only in ipsilateral LGNd neurons, and a 1 mg/kg Zn(2+) diet attenuated injury; and finally (6) NAD(+) synthesis and levels are involved given that LGNd neuronal death after VCA was dramatically reduced in Wld(s) animals, and by intraperitoneal pyruvate or nicotinamide. Zn(2+) toxicity is involved in serum and trophic deprivation-induced neuronal death.
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Affiliation(s)
- Christian T Sheline
- Department of Ophthalmology and the Neuroscience Center of Excellence, LSU Health Sciences Center, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA.
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Lee SB, Kwon IS, Park J, Lee KH, Ahn Y, Lee C, Kim J, Choi SY, Cho SW, Ahn JY. Ribosomal protein S3, a new substrate of Akt, serves as a signal mediator between neuronal apoptosis and DNA repair. J Biol Chem 2010; 285:29457-68. [PMID: 20605787 DOI: 10.1074/jbc.m110.131367] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RPS3, a conserved, eukaryotic ribosomal protein of the 40 S subunit, is required for ribosome biogenesis. Because ribosomal proteins are abundant and ubiquitous, they may have additional extraribosomal functions. Here, we show that human RPS3 is a physiological target of Akt kinase and a novel mediator of neuronal apoptosis. NGF stimulation resulted in phosphorylation of threonine 70 of RPS3 by Akt, and this phosphorylation was required for Akt binding to RPS3. RPS3 induced neuronal apoptosis, up-regulating proapoptotic proteins Dp5/Hrk and Bim by binding to E2F1 and acting synergistically with it. Akt-dependent phosphorylation of RPS3 inhibited its proapoptotic function and perturbed its interaction with E2F1. These events coincided with nuclear translocation and accumulation of RPS3, where it functions as an endonuclease. Nuclear accumulation of RPS3 results in an increase in DNA repair activity to some extent, thereby sustaining neuronal survival. Abolishment of Akt-mediated RPS3 phosphorylation through mutagenesis accelerated apoptotic cell death and severely compromised nuclear translocation of RPS3. Thus, our findings define an extraribosomal role of RPS3 as a molecular switch that accommodates apoptotic induction to DNA repair through Akt-mediated phosphorylation.
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Affiliation(s)
- Sang Bae Lee
- Department of Molecular Cell Biology, Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea
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Wang T, Liu YY, Wang X, Yang N, Zhu HB, Zuo PP. Protective effects of octacosanol on 6-hydroxydopamine-induced Parkinsonism in rats via regulation of ProNGF and NGF signaling. Acta Pharmacol Sin 2010; 31:765-74. [PMID: 20581854 DOI: 10.1038/aps.2010.69] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
AIM To investigate the protective effects of octacosanol in 6-hydroxydopamine-induced Parkinsonian rats and find whether octacosanol has effects on pro nerve growth factor (pro-NGF), NGF and the downstream effector proteins. METHODS Behavioral tests, enzymatic assay, tyrosine hydroxylase immunohistochemistry, TUNEL and Western blot were used to investigate the effects of octacosanol in this rat model of PD. RESULTS Oral administration of octacosanol (35-70 mg/kg, po for 14 d) significantly improved the behavioral impairments in rats induced by 6-OHDA and dose-dependently preserved the free radical scavenging capability of the striatum. Octacosanol treatment also effectively ameliorated morphological appearances of TH-positive neuronal cells in nigrostriatal systems and decreased the apoptotic cells induced by 6-OHDA in striatum. In addition, octacosanol strikingly blocked the 6-OHDA-induced increased expression of proNGF-p75NTR-sortilin death signaling complex and its downstream effector proteins. Meantime, octacosanol prevented the decreased levels of NGF, its receptors TrkA and p-Akt which together mediated the cell survival pathway. CONCLUSION The findings implicated that the anti-parkinsonism effects afforded by octacosanol might be mediated by its neuro-microenvironment improving potency through retrieving the ratios of proNGF:NGF and the respective receptors p75NTR:TrkA in vivo. Due to its excellent tolerability and non-toxicity, octacosanol may be a promising agent for PD treatment.
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Orellano EA, Rivera OJ, Chevres M, Chorna NE, González FA. Inhibition of neuronal cell death after retinoic acid-induced down-regulation of P2X7 nucleotide receptor expression. Mol Cell Biochem 2009; 337:83-99. [PMID: 19882109 DOI: 10.1007/s11010-009-0288-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2009] [Accepted: 10/08/2009] [Indexed: 01/12/2023]
Abstract
Apoptosis is a major mechanism for cell death in the nervous system during development. P2X(7) nucleotide receptors are ionotropic ATP receptors that mediate cell death under pathological conditions. We developed an in vitro protocol to investigate the expression and functional responses of P2X(7) nucleotide receptors during retinoic acid (RA)-induced neuronal differentiation of human SH-SY5Y neuroblastoma cells. Neuronal differentiation was examined measuring cellular growth arrest and neuritic processes elongation. We found that SH-SY5Y cells treated for 5 days with RA under low serum content exhibited a neuron-like phenotype with neurites extending more than twice the length of the cell body and cell growth arrest. Concurrently, we detected the abolishment of intracellular-free calcium mobilization and the down-regulation of P2X(7) nucleotide receptor protein expression that protected differentiated cells from neuronal cell death and reduced caspase-3 cleavage-induced by P2X(7) nucleotide receptor agonist. The role of P2X(7) nucleotide receptors in neuronal death was established by selectively antagonizing the receptor with KN-62 prior to its activation. We assessed the involvement of protein kinases and found that p38 signaling was activated in undifferentiated after nucleotide stimulation, but abolished by the differentiating RA pretreatment. Importantly, P2X(7) receptor-induced caspase-3 cleavage was blocked by the p38 protein kinase specific inhibitor PD169316. Taken together, our results suggest that RA treatment of human SH-SY5Y cells leads to decreased P2X(7) nucleotide receptor protein expression thus protecting differentiated cells from extracellular nucleotide-induced neuronal death, and p38 signaling pathway is critically involved in this protection of RA-differentiated cells.
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Affiliation(s)
- Elsie A Orellano
- Department of Biology, University of Puerto Rico, Río Piedras Campus, San Juan, PR, USA
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Dynamic changes of neuroskeletal proteins in DRGs underlie impaired axonal maturation and progressive axonal degeneration in type 1 diabetes. EXPERIMENTAL DIABETES RESEARCH 2009; 2009:793281. [PMID: 19834568 PMCID: PMC2761046 DOI: 10.1155/2009/793281] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 07/07/2009] [Indexed: 11/18/2022]
Abstract
We investigated mechanisms underlying progressive axonal dysfunction and structural deficits in type 1 BB/Wor-rats from 1 week to 10 month diabetes duration. Motor and sensory conduction velocities were decreased after 4 and 6 weeks of diabetes and declined further over the remaining 9 months. Myelinated sural nerve fibers showed progressive deficits in fiber numbers and sizes. Structural deficits in unmyelinated axonal size were evident at 2 month and deficits in number were present at 4 mo. These changes were preceded by decreased availability of insulin, C-peptide and IGF-1 and decreased expression of neurofilaments and β-III-tubulin. Upregulation of phosphorylating stress kinases like Cdk5, p-GSK-3β, and p42/44 resulted in increased phosphorylation of neurofilaments. Increasing activity of p-GSK-3β correlated with increasing phosphorylation of NFH, whereas decreasing Cdk5 correlated with diminishing phosphorylation of NFM. The data suggest that impaired neurotrophic support results in sequentially impaired synthesis and postranslational modifications of neuroskeletal proteins, resulting in progressive deficits in axonal function, maturation and size.
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Pedraza N, Rafel M, Navarro I, Encinas M, Aldea M, Gallego C. Mixed lineage kinase phosphorylates transcription factor E47 and inhibits TrkB expression to link neuronal death and survival pathways. J Biol Chem 2009; 284:32980-8. [PMID: 19801649 DOI: 10.1074/jbc.m109.038729] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
E47 is a basic helix-loop-helix transcription factor involved in neuronal differentiation and survival. We had previously shown that the basic helix-loop-helix protein E47 binds to E-box sequences within the promoter of the TrkB gene and activates its transcription. Proper expression of the TrkB receptor plays a key role in development and function of the vertebrate nervous system, and altered levels of TrkB have been associated with important human diseases. Here we show that E47 interacts with MLK2, a mixed lineage kinase (MLK) involved in JNK-mediated activation of programmed cell death. MLK2 enhances phosphorylation of the AD2 activation domain of E47 in vivo in a JNK-independent manner and phosphorylates in vitro defined serine and threonine residues within a loop-helix structure of AD2 that also contains a putative MLK docking site. Although these residues are essential for MLK2-mediated inactivation of E47, inhibition of MLKs by CEP11004 causes up-regulation of TrkB at a transcriptional level in cerebellar granule neurons and differentiating neuroblastoma cells. These findings allow us to propose a novel mechanism by which MLK regulates TrkB expression through phosphorylation of an activation domain of E47. This molecular link would explain why MLK inhibitors not only prevent activation of cell death processes but also enhance cell survival signaling as a key aspect of their neuroprotective potential.
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Affiliation(s)
- Neus Pedraza
- Departament de Ciències Mèdiques Bàsiques, IRBLLEIDA, Universitat de Lleida, 25008 Lleida, Catalonia, Spain
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Towers E, Gilley J, Randall R, Hughes R, Kristiansen M, Ham J. The proapoptotic dp5 gene is a direct target of the MLK-JNK-c-Jun pathway in sympathetic neurons. Nucleic Acids Res 2009; 37:3044-60. [PMID: 19304750 PMCID: PMC2685101 DOI: 10.1093/nar/gkp175] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The death of sympathetic neurons after nerve growth factor (NGF) withdrawal requires de novo gene expression. Dp5 was one of the first NGF withdrawal-induced genes to be identified and it encodes a proapoptotic BH3-only member of the Bcl-2 family. To study how dp5 transcription is regulated by NGF withdrawal we cloned the regulatory regions of the rat dp5 gene and constructed a series of dp5-luciferase reporter plasmids. In microinjection experiments with sympathetic neurons we found that three regions of dp5 contribute to its induction after NGF withdrawal: the promoter, a conserved region in the single intron, and sequences in the 3′ untranslated region of the dp5 mRNA. A construct containing all three regions is efficiently activated by NGF withdrawal and, like the endogenous dp5, its induction requires mixed-lineage kinase (MLK) and c-Jun N-terminal kinase (JNK) activity. JNKs phosphorylate the AP-1 transcription factor c-Jun, and thereby increase its activity. We identified a conserved ATF site in the dp5 promoter that binds c-Jun and ATF2, which is critical for dp5 promoter induction after NGF withdrawal. These results suggest that part of the mechanism by which the MLK-JNK-c-Jun pathway promotes neuronal apoptosis is by activating the transcription of the dp5 gene.
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Affiliation(s)
- Emily Towers
- Molecular Haematology and Cancer Biology Unit, Camelia Botnar Laboratories, UCL Institute of Child Health, London, UK
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Harguindey S, Orive G, Cacabelos R, Hevia EM, de Otazu RD, Arranz JL, Anitua E. An integral approach to the etiopathogenesis of human neurodegenerative diseases (HNDDs) and cancer. Possible therapeutic consequences within the frame of the trophic factor withdrawal syndrome (TFWS). Neuropsychiatr Dis Treat 2008; 4:1073-84. [PMID: 19337452 PMCID: PMC2646641 DOI: 10.2147/ndt.s3800] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A novel and integral approach to the understanding of human neurodegenerative diseases (HNDDs) and cancer based upon the disruption of the intracellular dynamics of the hydrogen ion (H(+)) and its physiopathology, is advanced. From an etiopathological perspective, the activity and/or deficiency of different growth factors (GFs) in these pathologies are studied, and their relationships to intracellular acid-base homeostasis reviewed. Growth and trophic factor withdrawal in HNDDs indicate the need to further investigate the potential utilization of certain GFs in the treatment of Alzheimer disease and other neurodegenerative diseases. Platelet abnormalities and the therapeutic potential of platelet-derived growth factors in these pathologies, either through platelet transfusions or other clinical methods, are considered. Finally, the etiopathogenic mechanisms of apoptosis and antiapoptosis in HNDDs and cancer are viewed as opposite biochemical and biological disorders of cellular acid-base balance and their secondary effects on intracellular signaling pathways and aberrant cell metabolism are considered in the light of the both the seminal and most recent data available. The "trophic factor withdrawal syndrome" is described for the first time in English-speaking medical literature, as well as a Darwinian-like interpretation of cellular behavior related to specific and nonspecific aspects of cell biology.
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Affiliation(s)
- Salvador Harguindey
- Institute of Clinical Biology and Metabolism, c/o Postas 13, 01004 Vitoria, Spain.
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Satoh T, Furuta K, Tomokiyo K, Namura S, Nakatsuka D, Sugie Y, Ishikawa Y, Hatanaka H, Suzuki M, Watanabe Y. Neurotrophic actions of novel compounds designed from cyclopentenone prostaglandins. J Neurochem 2008. [DOI: 10.1046/j.1471-4159.2001.00229.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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TABAKMAN RINAT, JIANG HAO, SHAHAR IRIS, ARIEN-ZAKAY HADAR, LEVINE ROBERTA, LAZAROVICI PHILIP. Neuroprotection by NGF in the PC12 In Vitro OGD Model. Ann N Y Acad Sci 2008. [DOI: 10.1111/j.1749-6632.2005.tb00013.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Abstract
Cell death is clearly an important factor in development, homeostasis, pathology and in aging, but medical efforts based on controlling cell death have not become major aspects of medicine. There are several reasons why hopes have been slow to be fulfilled, and they present indications for new directions in research. Most effort has focused on the machinery of cell death, or the proximate effectors of apoptosis and their closely associated and interacting proteins. But cells have many options other than apoptosis. These include autophagy, necrosis, atrophy and stepwise or other alternate means of self-disassembly. The response of a cell to a noxious or otherwise intimidating signal will depend heavily on the history, lineage and current status of the cell. Many metabolic and other processes adjust the sensitivity of cells to signals, and viruses aggressively attempt to regulate the death of their host cells. Another complicating factor is that many deathassociated proteins may have functions totally unrelated to their role in cell death, generating the possibility of undesirable side effects if one interferes with them. In the future, the challenge will be more to understand the challenge to the cell from a more global standpoint, including many more aspects of metabolism, and work toward alleviating or provoking the challenge in a targeted fashion.
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Affiliation(s)
- Richard A Lockshin
- Department of Biological Sciences, St. John's University, Queens, NY 11439, USA.
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Maruyama J, Miller JM, Ulfendahl M. Glial cell line-derived neurotrophic factor and antioxidants preserve the electrical responsiveness of the spiral ganglion neurons after experimentally induced deafness. Neurobiol Dis 2007; 29:14-21. [PMID: 17870569 PMCID: PMC2680080 DOI: 10.1016/j.nbd.2007.07.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 07/03/2007] [Accepted: 07/24/2007] [Indexed: 10/23/2022] Open
Abstract
Cochlear implant surgery is currently the therapy of choice for profoundly deaf patients. However, the functionality of cochlear implants depends on the integrity of the auditory spiral ganglion neurons. This study assesses the combined efficacy of two classes of agents found effective in preventing degeneration of the auditory nerve following deafness, neurotrophic factors, and antioxidants. Guinea pigs were deafened and treated for 4 weeks with either local administration of GDNF or a combination of GDNF and systemic injections of the antioxidants ascorbic acid and Trolox. The density of surviving spiral ganglion cells was significantly enhanced and the thresholds for eliciting an electrically evoked brain stem response were significantly reduced in GDNF treated animals compared to deafened-untreated. The addition of antioxidants significantly enhanced the evoked responsiveness over that observed with GDNF alone. The results suggest multiple sites of intervention in the rescue of these cells from deafferentation-induced cell death.
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Affiliation(s)
- Jun Maruyama
- Center for Hearing and Communication Research and Department of Clinical Neuroscience, Karolinska Institutet
- Department of Otolaryngology, Ehime University School of Medicine, Matsuyama, Japan
| | - Josef M. Miller
- Center for Hearing and Communication Research and Department of Clinical Neuroscience, Karolinska Institutet
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor, USA
| | - Mats Ulfendahl
- Center for Hearing and Communication Research and Department of Clinical Neuroscience, Karolinska Institutet
- Department of Otolaryngology, Karolinska University Hospital – Solna, Stockholm, Sweden
- Corresponding author. Address for correspondence: Mats Ulfendahl, PhD, Center for Hearing and Communication Research, Building M1, Karolinska University Hospital, Solna, SE-171 76 Stockholm, Sweden, Phone: +46 8 51776307 Fax: +46 8 301876,
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de Melo Reis RA, Herculano AM, da Silva MCC, dos Santos RM, do Nascimento JLM. In vitro toxicity induced by methylmercury on sympathetic neurons is reverted by l-cysteine or glutathione. Neurosci Res 2007; 58:278-84. [PMID: 17482303 DOI: 10.1016/j.neures.2007.03.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 03/25/2007] [Accepted: 03/26/2007] [Indexed: 11/17/2022]
Abstract
Methylmercury (MeHg) is related to several deleterious effects on the vertebrate nervous system and part of these effects are through interaction with sulfhydryl (-SH) group found in cellular proteins. We decided to characterize the dose-dependent effect of MeHg on the neurotoxicity and the neurite outgrowth induced effects on chick sympathetic neurons dissociated and purified in culture. In this model, MeHg inhibited neurite outgrowth (1-10 microM) and induced cell death (1-10 microM) after 48 h in culture. Since metal toxicity often generates reactive oxygen species, we tested if antioxidant compounds such as glutathione (GSH) or L-cysteine (L-cys) could block the deleterious effects promoted by MeHg. L-methionine, another sulfur-containing amino acid, but without a SH group, was also used in this work. We show that GSH (10-100 microM) and L-cys (100 microM), but not L-methionine (100 microM), fully blocked neurite degeneration and sympathetic neuron cell death in culture.
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Shi Z, Birman E, Saragovi HU. Neurotrophic rationale in glaucoma: A TrkA agonist, but not NGF or a p75 antagonist, protects retinal ganglion cellsin vivo. Dev Neurobiol 2007; 67:884-94. [PMID: 17506493 DOI: 10.1002/dneu.20360] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Glaucoma is a major cause of vision impairment, which arises from the sustained and progressive apoptosis of retinal ganglion cells (RGC), with ocular hypertension being a major risk or co-morbidity factor. Because RGC death often continues after normalization of ocular hypertension, growth factor-mediated protection of compromised neurons may be useful. However, the therapeutic use of nerve growth factor (NGF) has not proven effective at delaying RGC death in glaucoma. We postulated that one cause for the failure of NGF may be related to its binding to two receptors, TrkA and p75. These receptors have distinct cellular distribution in the retina and in neurons they induce complex and sometimes opposing activities. Here, we show in an in vivo therapeutic model of glaucoma that a selective agonist of the pro-survival TrkA receptor was effective at preventing RGC death. RGC loss was fully prevented by combining the selective agonist of TrkA with intraocular pressure-lowering drugs. In contrast, neither NGF nor an antagonist of the pro-apoptotic p75 receptor protected RGCs. These results further a neurotrophic rationale for glaucoma.
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Affiliation(s)
- ZhiHua Shi
- Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, Canada H3T 1E2
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Chiou SH, Kao CL, Chang YL, Ku HH, Tsai YJ, Lin HT, Yen CJ, Peng CH, Chiu JH, Tsai TH. Evaluation of anti-Fas ligand-induced apoptosis and neural differentiation of PC12 cells treated with nerve growth factor using small interfering RNA method and sampling by microdialysis. Anal Biochem 2007; 363:46-57. [PMID: 17306206 DOI: 10.1016/j.ab.2007.01.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2006] [Revised: 12/16/2006] [Accepted: 01/12/2007] [Indexed: 10/23/2022]
Abstract
The small interfering RNA (siRNA) method is an effective technique for silencing gene expression and is a useful tool for screening the gene functions in drug discovery. Our study found that nerve growth factor (NGF) can increase the cell viability of PC12 cells and that NGF induction up-regulates the expression of Bcl-2 detected by real-time reverse transcription-polymerase chain reaction (RT-PCR). To further investigate the role of Bcl-2 expression in NGF-treated PC12 cells, the plasmid of Bcl-2 siRNA was then transfected into PC12 cells. Moreover, to investigate and continuously monitor the real-time dynamic neurotransmitter release, and to compare with the time course of Bcl-2 expression, a liquid chromatography coupled with electrochemical detection (LC-ED) and with a microdialysis device was used. After 6h of NGF being added to the PC12 cell culture medium, the dopamine (DA) concentrations were significantly increased (P<0.05). This result is simultaneously compatible with the up-regulated messenger RNA (mRNA) expressions of tyrosine hydroxylase (TH), aromatic acid decarboxylase (AADC), and Bcl-2 by RT-PCR. Using the Bcl-2 siRNA method, our data revealed that NGF can inhibit Fas ligand (FasL)-induced apoptosis in PC12 cells through the activation of Bcl-2. The in vitro observation further demonstrated that NGF can stimulate the neurite development in PC12 cells through the activation of Bcl-2. Moreover, the DA concentrations of NGF induction were decreased specifically by Bcl-2 siRNA (P<0.05). In sum, our data support that NGF prevents Fas-induced apoptosis, facilitates neural differentiation, promotes dendritic formation, and increases DA release in PC12 cells through activation of Bcl-2.
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Affiliation(s)
- Shih-Hwa Chiou
- Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei 112, Taiwan
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48
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Liu D, Chan SL, de Souza-Pinto NC, Slevin JR, Wersto RP, Zhan M, Mustafa K, de Cabo R, Mattson MP. Mitochondrial UCP4 mediates an adaptive shift in energy metabolism and increases the resistance of neurons to metabolic and oxidative stress. Neuromolecular Med 2007; 8:389-414. [PMID: 16775390 DOI: 10.1385/nmm:8:3:389] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2005] [Revised: 02/21/2006] [Accepted: 02/23/2006] [Indexed: 11/11/2022]
Abstract
The high-metabolic demand of neurons and their reliance on glucose as an energy source places them at risk for dysfunction and death under conditions of metabolic and oxidative stress. Uncoupling proteins (UCPs) are mitochondrial inner membrane proteins implicated in the regulation of mitochondrial membrane potential (Deltapsim) and cellular energy metabolism. The authors cloned UCP4 cDNA from mouse and rat brain, and demonstrate that UCP4 mRNA is expressed abundantly in brain and at particularly high levels in populations of neurons believed to have high-energy requirements. Neural cells with increased levels of UCP4 exhibit decreased Deltapsim, reduced reactive oxygen species (ROS) production and decreased mitochondrial calcium accumulation. UCP4 expressing cells also exhibited changes of oxygen-consumption rate, GDP sensitivity, and response of Deltapsim to oligomycin that were consistent with mitochondrial uncoupling. UCP4 modulates neuronal energy metabolism by increasing glucose uptake and shifting the mode of ATP production from mitochondrial respiration to glycolysis, thereby maintaining cellular ATP levels. The UCP4-mediated shift in energy metabolism reduces ROS production and increases the resistance of neurons to oxidative and mitochondrial stress. Knockdown of UCP4 expression by RNA interference in primary hippocampal neurons results in mitochondrial calcium overload and cell death. UCP4-mRNA expression is increased in neurons exposed to cold temperatures and in brain cells of rats maintained on caloric restriction, suggesting a role for UCP4 in the previously reported antiageing and neuroprotective effects of caloric restriction. By shifting energy metabolism to reduce ROS production and cellular reliance on mitochondrial respiration, UCP4 can protect neurons against oxidative stress and calcium overload.
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Affiliation(s)
- Dong Liu
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD, USA
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49
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Vaughn AE, Deshmukh M. Essential postmitochondrial function of p53 uncovered in DNA damage-induced apoptosis in neurons. Cell Death Differ 2007; 14:973-81. [PMID: 17218959 DOI: 10.1038/sj.cdd.4402084] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In postmitotic sympathetic neurons, unlike most mitotic cells, death by apoptosis requires not only the release of cytochrome c from the mitochondria, but also an additional step to relieve X-linked inhibitor of apoptosis protein (XIAP)'s inhibition of caspases. Here, we examined the mechanism by which XIAP is inactivated following DNA damage and found that it is achieved by a mechanism completely different from that following apoptosis by nerve growth factor (NGF) deprivation. NGF deprivation relieves XIAP by selectively degrading it, whereas DNA damage overcomes XIAP via a p53-mediated induction of Apaf-1. Unlike wild-type neurons, p53-deficient neurons fail to overcome XIAP and remain resistant to cytochrome c after DNA damage. Restoring Apaf-1 induction in p53-deficient neurons is sufficient to overcome XIAP and sensitize cells to cytochrome c. Although a role for p53 in apoptosis upstream of cytochrome c release has been well established, this study uncovers an additional, essential role for p53 in regulating caspase activation downstream of mitochondria following DNA damage in neurons.
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Affiliation(s)
- A E Vaughn
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA
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Ribera J, Ayala V, Casas C. Involvement of c-Jun-JNK pathways in the regulation of programmed cell death of developing chick embryo spinal cord motoneurons. Dev Neurosci 2006; 29:438-51. [PMID: 17119319 DOI: 10.1159/000097318] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Accepted: 08/03/2006] [Indexed: 01/24/2023] Open
Abstract
Key features of developmentally regulated programmed cell death (PCD) have been described for the first time in the chick nervous system. JNK/c-Jun pathway was involved in early events determining normal and pathological neuronal death as shown in experimental models. In the chick embryo, PCD of motoneurons (MNs) in ovo occurs within a well-defined temporal window and can be subjected to experimental manipulation. Taking advantage of this in vivo system, we explored the role of c-Jun and JNK pathway in the regulation of PCD in MNs. By using specific antibodies against phospho-c-Jun (Ser 63, 73) and JNK we demonstrated that before MNs acquire apoptotic phenotype there is an increase in c-Jun. Blockage of neuromuscular activity by the GABA agonist muscimol reduces PCD and diminishes c-Jun immunoreactivity in MNs. Extensive induction of PCD, either due to injection of beta-bungarotoxin or limb bud removal, is also preceded by an increase in c-Jun immunoreactivity that is also associated with upregulation of phospho-c-Jun and JNK. Translocation of JNK from cytoplasm to MN nuclei was also detected. After acute application of beta-bungarotoxin, which is a strong apoptotic stimulus for MNs, c-Jun phosphorylation occurs on serine 73, whereas serine 63 is the main site for c-Jun phosphorylation after limb bud removal. These results demonstrated that the JNK/c-Jun pathway is involved in the decision phase of normal and induced apoptosis in MNs. Pharmacological interventions involving this pathway should be explored as a potential therapeutic target for promoting MN survival.
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Affiliation(s)
- Joan Ribera
- Universitat de Lleida, Facultat de Medicina, Departament de Ciències Mèdiques Bàsiques, Lleida, Spain.
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