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Saunders TL, Windley SP, Gervinskas G, Balka KR, Rowe C, Lane R, Tailler M, Nguyen TN, Ramm G, Lazarou M, De Nardo D, Kile BT, McArthur K. Exposure of the inner mitochondrial membrane triggers apoptotic mitophagy. Cell Death Differ 2024; 31:335-347. [PMID: 38396150 PMCID: PMC10923902 DOI: 10.1038/s41418-024-01260-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 12/20/2023] [Accepted: 01/24/2024] [Indexed: 02/25/2024] Open
Abstract
During apoptosis mediated by the intrinsic pathway, BAX/BAK triggers mitochondrial permeabilization and the release of cytochrome-c, followed by a dramatic remodelling of the mitochondrial network that results in mitochondrial herniation and the subsequent release of pro-inflammatory mitochondrial components. Here, we show that mitochondrial herniation and subsequent exposure of the inner mitochondrial membrane (IMM) to the cytoplasm, initiates a unique form of mitophagy to deliver these damaged organelles to lysosomes. IMM-induced mitophagy occurs independently of canonical PINK1/Parkin signalling and is driven by ubiquitination of the IMM. Our data suggest IMM-induced mitophagy is an additional safety mechanism that cells can deploy to contain damaged mitochondria. It may have particular relevance in situations where caspase activation is incomplete or inhibited, and in contexts where PINK1/Parkin-mitophagy is impaired or overwhelmed.
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Affiliation(s)
- Tahnee L Saunders
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia.
- Ubiquitin Signalling Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia.
| | - Simon P Windley
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Gediminas Gervinskas
- Monash Ramaciotti Centre for Cryo Electron Microscopy, Monash University, Melbourne, VIC, Australia
| | - Katherine R Balka
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Caitlin Rowe
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Rachael Lane
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Maximilien Tailler
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Thanh Ngoc Nguyen
- Ubiquitin Signalling Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Georg Ramm
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Monash Ramaciotti Centre for Cryo Electron Microscopy, Monash University, Melbourne, VIC, Australia
| | - Michael Lazarou
- Ubiquitin Signalling Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Dominic De Nardo
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Benjamin T Kile
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA, Australia
- Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW, 2010, Australia
| | - Kate McArthur
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia.
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia.
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Choo Z, Koh X, Wong MRE, Ashokan RM, Ali Ahamed NSB, Kang C, Kuick CH, Chang KTE, Larisch S, Loh AHP, Chen ZX. Targeted Degradation of XIAP is Sufficient and Specific to Induce Apoptosis in MYCN-overexpressing High-risk Neuroblastoma. CANCER RESEARCH COMMUNICATIONS 2023; 3:2386-2399. [PMID: 37874199 PMCID: PMC10681007 DOI: 10.1158/2767-9764.crc-23-0082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 07/22/2023] [Accepted: 10/16/2023] [Indexed: 10/25/2023]
Abstract
XIAP, the most potent mammalian inhibitor of apoptosis protein (IAP), critically restricts developmental culling of sympathetic neuronal progenitors, and is correspondingly overexpressed in most MYCN-amplified neuroblastoma tumors. Because apoptosis-related protein in the TGFβ signaling pathway (ARTS) is the only XIAP antagonist that directly binds and degrades XIAP, we evaluated the preclinical effectiveness and tolerability of XIAP antagonism as a novel targeting strategy for neuroblastoma. We found that antagonism of XIAP, but not other IAPs, triggered apoptotic death in neuroblastoma cells. XIAP silencing induced apoptosis while overexpression conferred protection from drug-induced apoptosis. From a screen of IAP inhibitors, first-in-class ARTS mimetic A4 was most effective against high-risk and high XIAP-expressing neuroblastoma cells, and least toxic toward normal liver- and bone marrow-derived cells, compared with pan-IAP antagonists. On target engagement assays and nuclear magnetic resonance spectroscopy, A4 was observed to degrade rather than inhibit XIAP, catalyzing rapid degradation of XIAP through the ubiquitin-proteasome pathway. In MYCN-amplified neuroblastoma patient-derived xenografts, A4 significantly prolonged survival as a single agent, and demonstrated synergism with standard-of-care agents to reduce their effective required doses 3- to 6-fold. Engagement and degradation of XIAP by ARTS mimetics is a novel targeting strategy for neuroblastoma that may be especially effective against MYCN-amplified disease with intrinsically high XIAP expression. First-in-class ARTS mimetic A4 demonstrates preclinical efficacy and warrants further development and study. SIGNIFICANCE XIAP degradation is sufficient to kill MYCN-amplified neuroblastoma which overexpresses and relies on XIAP as a brake against cell death, without affecting normal cells.
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Affiliation(s)
- Zhang'E Choo
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Xiaoying Koh
- Experimental Drug Development Centre, A*STAR, Singapore
| | - Megan Rui En Wong
- VIVA-KKH Paediatric Brain and Solid Tumour Programme, Children's Blood and Cancer Centre, KK Women's and Children's Hospital, Singapore
| | - Ruth Minothini Ashokan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Nurul Suhana Binte Ali Ahamed
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - CongBao Kang
- Experimental Drug Development Centre, A*STAR, Singapore
| | - Chik Hong Kuick
- Department of Pathology and Laboratory Medicine, KK Women's and Children's Hospital, Singapore
| | - Kenneth Tou En Chang
- VIVA-KKH Paediatric Brain and Solid Tumour Programme, Children's Blood and Cancer Centre, KK Women's and Children's Hospital, Singapore
- Department of Pathology and Laboratory Medicine, KK Women's and Children's Hospital, Singapore
- Duke NUS Medical School, Singapore
| | - Sarit Larisch
- Cell Death and Cancer Research Laboratory, Department of Human Biology and Medical Sciences, University of Haifa, Haifa, Israel
| | - Amos Hong Pheng Loh
- VIVA-KKH Paediatric Brain and Solid Tumour Programme, Children's Blood and Cancer Centre, KK Women's and Children's Hospital, Singapore
- Duke NUS Medical School, Singapore
- Cell Death and Cancer Research Laboratory, Department of Human Biology and Medical Sciences, University of Haifa, Haifa, Israel
- Department of Paediatric Surgery, KK Women's and Children's Hospital, Singapore
| | - Zhi Xiong Chen
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- VIVA-KKH Paediatric Brain and Solid Tumour Programme, Children's Blood and Cancer Centre, KK Women's and Children's Hospital, Singapore
- National University Cancer Institute, Singapore, National University Health System, Singapore
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Acute radiofrequency electromagnetic radiation exposure impairs neurogenesis and causes neuronal DNA damage in the young rat brain. Neurotoxicology 2023; 94:46-58. [PMID: 36336097 DOI: 10.1016/j.neuro.2022.11.001] [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: 06/17/2022] [Revised: 11/02/2022] [Accepted: 11/02/2022] [Indexed: 11/05/2022]
Abstract
A mobile phone is now a commonly used device for digital media and communication among all age groups. Young adolescents use it for longer durations, which exposes them to radiofrequency electromagnetic radiation (RF-EMR). This exposure can lead to neuropsychiatric changes. The underlying cellular mechanism behind these changes requires detailed investigation. In the present study, we investigated the effect of RF-EMR emitted from mobile phones on young adolescent rat brains. Wistar rats (5 weeks, male) were exposed to RF-EMR signal (2115 MHz) at a head average specific absorption rate (SAR) of 1.51 W/kg continuously for 8 h. Higher level of lipid peroxidation, carbon-centered lipid radicals, and single-strand DNA damage was observed in the brain of rat exposed to RF-EMR. The number of BrdU-positive cells in the dentate gyrus (DG) decreased in RF-EMR-exposed rats, indicating reduced neurogenesis. RF-EMR exposure also induced degenerative changes and neuronal loss in DG neurons but had no effect on the CA3 and CA1 neurons of the hippocampus and cerebral cortex. The activity of Pro-caspase3 did not increase upon exposure in any of the brain regions, pointing out that degeneration observed in the DG region is not dependent on caspase activation. Results indicate that short-term acute exposure to RF-EMR induced the generation of carbon-centered lipid radicals and nuclear DNA damage, both of which likely played a role in the impaired neurogenesis and neuronal degeneration seen in the young brain's hippocampus region. The understanding of RF-EMR-induced alteration in the brain at the cellular level will help develop appropriate interventions for reducing its adverse impact.
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Coccia E, Solé M, Comella JX. FAIM-L - SIVA-1: Two Modulators of XIAP in Non-Apoptotic Caspase Function. Front Cell Dev Biol 2022; 9:826037. [PMID: 35083225 PMCID: PMC8784879 DOI: 10.3389/fcell.2021.826037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022] Open
Abstract
Apoptosis is crucial for the correct development of the nervous system. In adulthood, the same protein machinery involved in programmed cell death can control neuronal adaptiveness through modulation of synaptic pruning and synaptic plasticity processes. Caspases are the main executioners in these molecular pathways, and their strict regulation is essential to perform neuronal remodeling preserving cell survival. FAIM-L and SIVA-1 are regulators of caspase activation. In this review we will focus on FAIM-L and SIVA-1 as two functional antagonists that modulate non-apoptotic caspase activity in neurons. Their participation in long-term depression and neurite pruning will be described in base of the latest studies performed. In addition, the association of FAIM-L non-apoptotic functions with the neurodegeneration process will be reviewed.
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Affiliation(s)
- Elena Coccia
- Cell Signaling and Apoptosis Group, Vall d'Hebron Institute of Research (VHIR), Barcelona, Spain.,Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid, Spain.,Departament de Bioquímica I Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
| | - Montse Solé
- Cell Signaling and Apoptosis Group, Vall d'Hebron Institute of Research (VHIR), Barcelona, Spain.,Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid, Spain.,Departament de Bioquímica I Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
| | - Joan X Comella
- Cell Signaling and Apoptosis Group, Vall d'Hebron Institute of Research (VHIR), Barcelona, Spain.,Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII, Madrid, Spain.,Departament de Bioquímica I Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
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Gao H, Zhang Y, Xue H, Zhang Q, Zhang Y, Shen Y, Bing X. Long Non-coding RNA Peg13 Alleviates Hypoxic-Ischemic Brain Damage in Neonatal Mice via miR-20a-5p/XIAP Axis. Neurochem Res 2022; 47:656-666. [PMID: 35043374 DOI: 10.1007/s11064-021-03474-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 01/01/2023]
Abstract
Long noncoding RNA (LncRNA) Peg13 has been demonstrated to protect against neurological diseases. However, its underlying mechanism in the progression of hypoxic-ischemic brain damage (HIBD) has not been well investigated. The expression of target genes was determined in neonatal mice with HIBD and in mouse hippocampal neurons during oxygen-glucose deprivation (OGD) using quantitative real-time PCR (qRT-PCR) and immunoblotting. Functional assays, including CCK-8 cell viability and apoptotic cell detection using TdT mediated dUTP nick ending labeling (TUNEL) assay were used to examine the neuroprotective role of Peg13 in mouse hippocampal neurons. Luciferase assays were performed to determine the regulatory mechanism of Peg13 in OGD-induced neuronal apoptosis. Peg13 was reduced in HIBD mice and OGD-treated mouse hippocampal neurons. Altered Peg13 expression relieved OGD-induced neuronal apoptosis. Mechanistically, Peg13 may serve as a sponge for miR-20a-5p to increase the expression of X chromosome-linked inhibitor of apoptosis (XIAP), a downstream target of miR-20a-5p. Our study showed that Peg13 fulfilled its anti-apoptotic function in neurons through suppressing XIAP expression by sponging miR-20a-5p. Together, Peg13 binds to miR-20a-5p to upregulate XIAP and alleviate HIBD in neonatal mice. The Peg13/miR-20a-5p/XIAP competing endogenous RNA (ceRNA) axis could be a potential therapeutic target for HIBD.
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Affiliation(s)
- Huan Gao
- Department of Children's Rehabilitation, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Yue Zhang
- Department of Ophthalmonogy, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Huijing Xue
- Department of Children's Rehabilitation, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Qifei Zhang
- Department of Children's Rehabilitation, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Yan Zhang
- Department of Cardiology, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Yusi Shen
- Second Department of Orthopedic Rehabilitation, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Xiaosan Bing
- Department of Pediatrics, Xiangyang Central Hospital, Affiliated Hospital of Hubei University of Arts and Science, No. 136, Jingzhou Street, Xiangcheng District, Xiangyang, 441000, Hubei, China.
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Ramos PM, Bell LC, Wohlgemuth SE, Scheffler TL. Mitochondrial Function in Oxidative and Glycolytic Bovine Skeletal Muscle Postmortem. MEAT AND MUSCLE BIOLOGY 2021. [DOI: 10.22175/mmb.11698] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Meat quality is traditionally associated with anaerobic metabolism due to cessation of the oxygen supply post-mortem. However, mitochondrial (mt) function early postmortem may affect the development of meat quality characteristics, such as adenosine triphosphate levels and pH decline. Therefore, the objective of this study was to evaluate mt function ex vivo during the first 24 h postmortem in muscles with differences in mt content. Samples from longissimus lumborum (LL) and diaphragm (Dia) were taken from steers (n = 6) at 1, 3, and 24 h postmortem and frozen to determine citrate synthase (CS) activity and mt protein expression (immunodetection) or were fresh-preserved for high-resolution respirometry. Integrative oxygen consumption rate (picomoles per second per milligram of tissue) was measured and normalized to CS activity as a proxy for mt content (intrinsic mt function, picomoles per second per unit CS). CS activity (P < 0.001) and mt protein expression (P < 0.001) were greater in Dia, which was reflected in mt respiration. Muscle type affected (P < 0.001) integrative leak respiration and was greater in mt from Dia; oxidative phosphorylation (OXPHOS) was also greater in Dia and influenced by time postmortem (muscle × time: P = 0.01). Intrinsic leak and OXPHOS were affected by muscle and time (muscle × time: P = 0.05 and P = 0.01, respectively), with the most pronounced differences at 24 h postmortem. Stimulation of OXPHOS by cytochrome c as an indicator of outer mt membrane integrity was influenced by muscle and time postmortem (muscle × time: P = 0.03); it was greater in mt from LL. Despite intrinsic differences in respiratory function at 24 h, mt from both muscles were intact and coupled at 1 h postmortem. Reduced content and respiratory function in mt from LL are associated with early fragmentation, which could impact protease activation and subsequently meat quality.
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Liao Z, Yang X, Wang W, Deng W, Zhang Y, Song A, Ni B, Zhao H, Zhang S, Li Z. hucMSCs transplantation promotes locomotor function recovery, reduces apoptosis and inhibits demyelination after SCI in rats. Neuropeptides 2021; 86:102125. [PMID: 33486279 DOI: 10.1016/j.npep.2021.102125] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/18/2020] [Accepted: 01/10/2021] [Indexed: 11/23/2022]
Abstract
AIMS Spinal cord injury (SCI) can cause a variety of cells apoptosis, neurodegeneration, and eventually permanent paralysis. This study aimed to examine whether transplanting human umbilical cord mesenchymal stem cells (hucMSCs) can promote locomotor function recovery, reduce apoptosis and inhibit demyelination in SCI models. MAIN METHODS Rats were allocated into Sham group (spinal cord exposure only), SCI + PBS group (spinal cord impact plus phosphate-buffered saline (PBS) injections), SCI + hucMSCs group (spinal cord impact plus hucMSCs injections) groups. Behavioral tests, Basso-Beattie-Bresnahan locomotion scores (BBB scores), were carried out at 0, 3, 7, 14, 21, 28 days after SCI surgery. Hematoxylin-eosin staining observed spinal cord morphology. Nissl staining detected the number of nissl bodies. Myelin basic protein (MBP) and oligodendrocyte (CNPase) were examed by immunohistochemical staining. The apoptosis of oligodendrocyte and neurons were detected by immunofluorescence. RESULTS The 28-day behavioral test showed that the BBB score of rats in the SCI + hucMSCs group increased significantly, comparing to the SCI + PBS group. The numbers of nissl bodies and myelin sheath in the damaged area of SCI + hucMSCs group were also significantly increased compared to the SCI + PBS group. HucMSCs transplanting decreased the expression of protein level of Caspase-3 and Bax and increased the Bcl-2, MBP and CNPase, rescued the apoptosis of neurons and the oligodendrocyte. CONCLUSION These results showed that hucMSCs can improve motor function, tissue repairing and reducing apoptosis in SCI rats.
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Affiliation(s)
- Ziling Liao
- Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China
| | - Xiuzhen Yang
- Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China
| | - Wei Wang
- Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China
| | - Weiyue Deng
- Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China
| | - Yuying Zhang
- Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China
| | - Aishi Song
- Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China
| | - Bin Ni
- NHC Key Laboratory of Birth Defect for Research and Prevention, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan 410008, China
| | - Huifang Zhao
- CAS Key Laboratory of Regenerative Biology, Guangzhou Institutes of Biomedicine and Health and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Shusheng Zhang
- Changsha Stomatological Hospital, Changsha, Hunan 410004, China
| | - Zhiyuan Li
- Department of Anatomy and Neurobiology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China; NHC Key Laboratory of Birth Defect for Research and Prevention, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan 410008, China; CAS Key Laboratory of Regenerative Biology, Guangzhou Institutes of Biomedicine and Health and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; GZMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangdong, China; Changsha Stomatological Hospital, Changsha, Hunan 410004, China; Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou 510005, China.
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p53 is required for nuclear but not mitochondrial DNA damage-induced degeneration. Cell Death Dis 2021; 12:104. [PMID: 33473103 PMCID: PMC7817838 DOI: 10.1038/s41419-020-03373-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 12/16/2020] [Accepted: 12/22/2020] [Indexed: 12/18/2022]
Abstract
While the consequences of nuclear DNA damage have been well studied, the exact consequences of acute and selective mitochondrial DNA (mtDNA) damage are less understood. DNA damaging chemotherapeutic drugs are known to activate p53-dependent apoptosis in response to sustained nuclear DNA damage. While it is recognized that whole-cell exposure to these drugs also damages mtDNA, the specific contribution of mtDNA damage to cellular degeneration is less clear. To examine this, we induced selective mtDNA damage in neuronal axons using microfluidic chambers that allow for the spatial and fluidic isolation of neuronal cell bodies (containing nucleus and mitochondria) from the axons (containing mitochondria). Exposure of the DNA damaging drug cisplatin selectively to only the axons induced mtDNA damage in axonal mitochondria, without nuclear damage. We found that this resulted in the selective degeneration of only the targeted axons that were exposed to DNA damage, where ROS was induced but mitochondria were not permeabilized. mtDNA damage-induced axon degeneration was not mediated by any of the three known axon degeneration pathways: apoptosis, axon pruning, and Wallerian degeneration, as Bax-deficiency, or Casp3-deficiency, or Sarm1-deficiency failed to protect the degenerating axons. Strikingly, p53, which is essential for degeneration after nuclear DNA damage, was also not required for degeneration induced with mtDNA damage. This was most evident when the p53-deficient neurons were globally exposed to cisplatin. While the cell bodies of p53-deficient neurons were protected from degeneration in this context, the axons farthest from the cell bodies still underwent degeneration. These results highlight how whole cell exposure to DNA damage activates two pathways of degeneration; a faster, p53-dependent apoptotic degeneration that is triggered in the cell bodies with nuclear DNA damage, and a slower, p53-independent degeneration that is induced with mtDNA damage.
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Furusawa K, Emoto K. Scrap and Build for Functional Neural Circuits: Spatiotemporal Regulation of Dendrite Degeneration and Regeneration in Neural Development and Disease. Front Cell Neurosci 2021; 14:613320. [PMID: 33505249 PMCID: PMC7829185 DOI: 10.3389/fncel.2020.613320] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/04/2020] [Indexed: 01/01/2023] Open
Abstract
Dendrites are cellular structures essential for the integration of neuronal information. These elegant but complex structures are highly patterned across the nervous system but vary tremendously in their size and fine architecture, each designed to best serve specific computations within their networks. Recent in vivo imaging studies reveal that the development of mature dendrite arbors in many cases involves extensive remodeling achieved through a precisely orchestrated interplay of growth, degeneration, and regeneration of dendritic branches. Both degeneration and regeneration of dendritic branches involve precise spatiotemporal regulation for the proper wiring of functional networks. In particular, dendrite degeneration must be targeted in a compartmentalized manner to avoid neuronal death. Dysregulation of these developmental processes, in particular dendrite degeneration, is associated with certain types of pathology, injury, and aging. In this article, we review recent progress in our understanding of dendrite degeneration and regeneration, focusing on molecular and cellular mechanisms underlying spatiotemporal control of dendrite remodeling in neural development. We further discuss how developmental dendrite degeneration and regeneration are molecularly and functionally related to dendrite remodeling in pathology, disease, and aging.
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Affiliation(s)
- Kotaro Furusawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Kazuo Emoto
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Tokyo, Japan
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10
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Liu X, Cui X, Guan G, Dong Y, Zhang Z. microRNA-192-5p is involved in nerve repair in rats with peripheral nerve injury by regulating XIAP. Cell Cycle 2020; 19:326-338. [PMID: 31944167 PMCID: PMC7028159 DOI: 10.1080/15384101.2019.1710916] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/20/2019] [Accepted: 11/07/2019] [Indexed: 02/06/2023] Open
Abstract
Objective: MicroRNAs (miRNAs) have been demonstrated to engage in the nerve injury, while the effect of microRNA-192-5p (miR-192-5p) on the nerve repair has not yet been well understood. This study is performed to investigate how miR-192-5p affects nerve repair in rats with peripheral nerve injury by regulating X-linked inhibitor of apoptosis protein (XIAP).Methods: The rat model of left sciatic nerve injury was established, and the expression of miR-192-5p was then detected. A series of experiments were conducted to investigate the role of miR-192-5p on nerve repair in rats with peripheral nerve injury. The expression of apoptosis-related proteins (Caspase-3, Bax and Bcl-2) and nerve repair factors (NGF, BDNF, and GAP-43) was measured. Bioinformatics analysis and dual-luciferase reporter gene assay confirmed the targeting relationship between miR-192-5p and XIAP.Results: MiR-192-5p inhibition promoted the recovery of sensory function and the recovery and regeneration in rats with sciatic nerve injury. MiR-192-5p inhibition promoted the recovery of muscle atrophy caused by nerve injury. MiR-192-5p inhibition inhibited neuronal apoptosis by affecting the expression of apoptosis-related proteins and promoted the recovery of nerve function by elevating the expression of nerve repair factors induced by peripheral nerve injury. Bioinformatics analysis and dual-luciferase reporter gene assay confirmed that XIAP was a target gene of miR-192-5p.Conclusion: This study demonstrates that miR-192-5p inhibition can up-regulate the expression of XIAP, decrease the apoptosis of nerve cells, and promote the repair and regeneration of peripheral nerve injury.
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Affiliation(s)
- Xing Liu
- Department of orthopedics, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
| | - Xintao Cui
- Department of orthopedics, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
| | - Guangwei Guan
- Department of orthopedics, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
| | - Ying Dong
- Department of orthopedics, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
| | - Zhenyu Zhang
- Department of orthopedics, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
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11
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Bock FJ, Tait SWG. Mitochondria as multifaceted regulators of cell death. Nat Rev Mol Cell Biol 2020; 21:85-100. [PMID: 31636403 DOI: 10.1038/s41580-019-0173-8] [Citation(s) in RCA: 1204] [Impact Index Per Article: 301.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2019] [Indexed: 12/12/2022]
Abstract
Through their many and varied metabolic functions, mitochondria power life. Paradoxically, mitochondria also have a central role in apoptotic cell death. Upon induction of mitochondrial apoptosis, mitochondrial outer membrane permeabilization (MOMP) usually commits a cell to die. Apoptotic signalling downstream of MOMP involves cytochrome c release from mitochondria and subsequent caspase activation. As such, targeting MOMP in order to manipulate cell death holds tremendous therapeutic potential across different diseases, including neurodegenerative diseases, autoimmune disorders and cancer. In this Review, we discuss new insights into how mitochondria regulate apoptotic cell death. Surprisingly, recent data demonstrate that besides eliciting caspase activation, MOMP engages various pro-inflammatory signalling functions. As we highlight, together with new findings demonstrating cell survival following MOMP, this pro-inflammatory role suggests that mitochondria-derived signalling downstream of pro-apoptotic cues may also have non-lethal functions. Finally, we discuss the importance and roles of mitochondria in other forms of regulated cell death, including necroptosis, ferroptosis and pyroptosis. Collectively, these new findings offer exciting, unexplored opportunities to target mitochondrial regulation of cell death for clinical benefit.
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Affiliation(s)
- Florian J Bock
- Cancer Research UK Beatson Institute, Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Stephen W G Tait
- Cancer Research UK Beatson Institute, Institute of Cancer Sciences, University of Glasgow, Glasgow, UK.
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12
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Hollville E, Romero SE, Deshmukh M. Apoptotic cell death regulation in neurons. FEBS J 2019; 286:3276-3298. [PMID: 31230407 DOI: 10.1111/febs.14970] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/15/2019] [Accepted: 06/20/2019] [Indexed: 12/16/2022]
Abstract
Apoptosis plays a major role in shaping the developing nervous system during embryogenesis as neuronal precursors differentiate to become post-mitotic neurons. However, once neurons are incorporated into functional circuits and become mature, they greatly restrict their capacity to die via apoptosis, thus allowing the mature nervous system to persist in a healthy and functional state throughout life. This robust restriction of the apoptotic pathway during neuronal differentiation and maturation is defined by multiple unique mechanisms that function to more precisely control and restrict the intrinsic apoptotic pathway. However, while these mechanisms are necessary for neuronal survival, mature neurons are still capable of activating the apoptotic pathway in certain pathological contexts. In this review, we highlight key mechanisms governing the survival of post-mitotic neurons, while also detailing the physiological and pathological contexts in which neurons are capable of overcoming this high apoptotic threshold.
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Affiliation(s)
| | - Selena E Romero
- Neuroscience Center, UNC Chapel Hill, NC, USA.,Department of Cell Biology and Physiology, UNC Chapel Hill, NC, 27599-7250, USA
| | - Mohanish Deshmukh
- Neuroscience Center, UNC Chapel Hill, NC, USA.,Department of Cell Biology and Physiology, UNC Chapel Hill, NC, 27599-7250, USA
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13
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Naito M, Ohoka N, Shibata N. SNIPERs-Hijacking IAP activity to induce protein degradation. DRUG DISCOVERY TODAY. TECHNOLOGIES 2019; 31:35-42. [PMID: 31200857 DOI: 10.1016/j.ddtec.2018.12.002] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 12/11/2018] [Accepted: 12/18/2018] [Indexed: 12/28/2022]
Abstract
The induction of protein degradation by chimeric small molecules represented by proteolysis-targeting chimeras (PROTACs) is an emerging approach for novel drug development. We have developed a series of chimeric molecules termed specific and non-genetic inhibitor of apoptosis protein (IAP)-dependent protein erasers (SNIPERs) that recruit IAP ubiquitin ligases to effect targeted degradation. Unlike the chimeric molecules that recruit von Hippel-Lindau and cereblon ubiquitin ligases, SNIPERs induce simultaneous degradation of IAPs such as cIAP1 and XIAP along with the target proteins. Because cancer cells often overexpress IAPs-a mechanism involved in the resistance to cancer therapy-SNIPERs could be used to kill cancer cells efficiently.
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Affiliation(s)
- Mikihiko Naito
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki 210-9501, Japan.
| | - Nobumichi Ohoka
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki 210-9501, Japan
| | - Norihito Shibata
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki 210-9501, Japan
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14
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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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15
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XIAP RING domain mediates miR-4295 expression and subsequently inhibiting p63α protein translation and promoting transformation of bladder epithelial cells. Oncotarget 2018; 7:56540-56557. [PMID: 27447744 PMCID: PMC5302933 DOI: 10.18632/oncotarget.10645] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 06/13/2016] [Indexed: 12/12/2022] Open
Abstract
The X-linked inhibitor of apoptosis protein (XIAP) contains three N-terminal BIR domains that mediate anti-apoptosis and one C-terminal RING finger domain whose function(s) are not fully defined. Here we show that the RING domain of XIAP strongly inhibits the expression of p63α, a known tumor suppressor. XIAP knockdown in urothelial cells or RING deletion in knockin mice markedly upregulates p63α expression. This RING-mediated p63α downregulation is critical for the malignant transformation of normal urothelial cells following EGF treatment. We further show that the RING domain promotes Sp1-mediated transcription of miR-4295 which targets the 3′UTR of p63α mRNA and consequently inhibits p63α translation. Our results reveal a previously unknown function of the RING of XIAP in promoting miR-4295 transcription, thereby reducing p63α translation and enhancing urothelial transformation. Our data offer novel insights into the multifunctional effects of the XIAP RING domain on urothelial tumorigenesis and the potential for targeting this frequently overexpressed protein as a therapeutic alternative.
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16
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Choo Z, Koh RYL, Wallis K, Koh TJW, Kuick CH, Sobrado V, Kenchappa RS, Loh AHP, Soh SY, Schlisio S, Chang KTE, Chen ZX. XAF1 promotes neuroblastoma tumor suppression and is required for KIF1Bβ-mediated apoptosis. Oncotarget 2018; 7:34229-39. [PMID: 27097110 PMCID: PMC5085151 DOI: 10.18632/oncotarget.8748] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 03/28/2016] [Indexed: 11/25/2022] Open
Abstract
Neuroblastoma is an aggressive, relapse-prone childhood tumor of the sympathetic nervous system. Current treatment modalities do not fully exploit the genetic basis between the different molecular subtypes and little is known about the targets discovered in recent mutational and genetic studies. Neuroblastomas with poor prognosis are often characterized by 1p36 deletion, containing the kinesin gene KIF1B. Its beta isoform, KIF1Bβ, is required for NGF withdrawal-dependent apoptosis, mediated by the induction of XIAP-associated Factor 1 (XAF1). Here, we showed that XAF1 low expression correlates with poor survival and disease status. KIF1Bβ deletion results in loss of XAF1 expression, suggesting that XAF1 is indeed a downstream target of KIF1Bβ. XAF1 silencing protects from NGF withdrawal and from KIF1Bβ-mediated apoptosis. Overexpression of XAF1 impairs tumor progression whereas knockdown of XAF1 promotes tumor growth, suggesting that XAF1 may be a candidate tumor suppressor in neuroblastoma and its associated pathway may be important for developing future interventions.
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Affiliation(s)
- Zhang'e Choo
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, S117597, Singapore, Singapore
| | - Rachel Yu Lin Koh
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, S117597, Singapore, Singapore
| | - Karin Wallis
- Ludwig Cancer Research (Stockholm), Karolinska Institutet, SE-17177, Stockholm, Sweden
| | - Timothy Jia Wei Koh
- School of Life Sciences and Technology, Ngee Ann Polytechnic, S599489, Singapore, Singapore
| | - Chik Hong Kuick
- Department of Pathology and Laboratory Medicine, KK Women's and Children's Hospital, S299899, Singapore
| | - Veronica Sobrado
- Ludwig Cancer Research (Stockholm), Karolinska Institutet, SE-17177, Stockholm, Sweden
| | | | - Amos Hong Pheng Loh
- Department of Paediatric Surgery, KK Women's and Children's Hospital, S299899, Singapore, Singapore
| | - Shui Yen Soh
- Department of Paediatric Hematology/Oncology, KK Women's and Children's Hospital, S299899, Singapore, Singapore
| | - Susanne Schlisio
- Ludwig Cancer Research (Stockholm), Karolinska Institutet, SE-17177, Stockholm, Sweden.,Department of Microbiology and Tumor and Cell Biology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Kenneth Tou En Chang
- Department of Pathology and Laboratory Medicine, KK Women's and Children's Hospital, S299899, Singapore
| | - Zhi Xiong Chen
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, S117597, Singapore, Singapore
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17
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Hollville E, Deshmukh M. Physiological functions of non-apoptotic caspase activity in the nervous system. Semin Cell Dev Biol 2017; 82:127-136. [PMID: 29199140 DOI: 10.1016/j.semcdb.2017.11.037] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/22/2017] [Accepted: 11/29/2017] [Indexed: 12/15/2022]
Abstract
Caspases are cysteine proteases that play important and well-defined roles in apoptosis and inflammation. Increasing evidence point to alternative functions of caspases where restricted and localized caspase activation within neurons allows for a variety of non-apoptotic and non-inflammatory processes required for brain development and function. In this review, we highlight sublethal caspase functions in axon and dendrite pruning, neurite outgrowth and dendrite branches formation, as well as in long-term depression and synaptic plasticity. Importantly, as non-apoptotic activity of caspases is often confined in space and time in neurons, we also discuss the mechanisms that restrict caspase activity in order to maintain the neuronal networks in a healthy and functional state.
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Affiliation(s)
| | - Mohanish Deshmukh
- Neuroscience Center, UNC Chapel Hill, Chapel Hill, NC, USA; Department of Cell Biology and Physiology, UNC Chapel Hill, Chapel Hill, NC, USA.
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18
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Fukuda Y, Li Y, Segal RA. A Mechanistic Understanding of Axon Degeneration in Chemotherapy-Induced Peripheral Neuropathy. Front Neurosci 2017; 11:481. [PMID: 28912674 PMCID: PMC5583221 DOI: 10.3389/fnins.2017.00481] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/14/2017] [Indexed: 12/12/2022] Open
Abstract
Chemotherapeutic agents cause many short and long term toxic side effects to peripheral nervous system (PNS) that drastically alter quality of life. Chemotherapy-induced peripheral neuropathy (CIPN) is a common and enduring disorder caused by several anti-neoplastic agents. CIPN typically presents with neuropathic pain, numbness of distal extremities, and/or oversensitivity to thermal or mechanical stimuli. This adverse side effect often requires a reduction in chemotherapy dosage or even discontinuation of treatment. Currently there are no effective treatment options for CIPN. While the underlying mechanisms for CIPN are not understood, current data identify a “dying back” axon degeneration of distal nerve endings as the major pathology in this disorder. Therefore, mechanistic understanding of axon degeneration will provide insights into the pathway and molecular players responsible for CIPN. Here, we review recent findings that expand our understanding of the pathogenesis of CIPN and discuss pathways that may be shared with the axonal degeneration that occurs during developmental axon pruning and during injury-induced Wallerian degeneration. These mechanistic insights provide new avenues for development of therapies to prevent or treat CIPN.
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Affiliation(s)
- Yusuke Fukuda
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
| | - Yihang Li
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
| | - Rosalind A Segal
- Department of Neurobiology, Harvard Medical SchoolBoston, MA, United States.,Department of Cancer Biology, Dana-Farber Cancer InstituteBoston, MA, United States
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19
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Hayes HL, Peterson BS, Haldeman JM, Newgard CB, Hohmeier HE, Stephens SB. Delayed apoptosis allows islet β-cells to implement an autophagic mechanism to promote cell survival. PLoS One 2017; 12:e0172567. [PMID: 28212395 PMCID: PMC5315295 DOI: 10.1371/journal.pone.0172567] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/24/2017] [Indexed: 01/09/2023] Open
Abstract
Increased β-cell death coupled with the inability to replicate existing β-cells drives the decline in β-cell mass observed in the progression of both major forms of diabetes. Understanding endogenous mechanisms of islet cell survival could have considerable value for the development of novel strategies to limit β-cell loss and thereby promote β-cell recovery. Insulinoma cells have provided useful insight into β-cell death pathways but observations made in cell lines sometimes fail to translate to primary islets. Here, we report dramatic differences in the temporal regulation and engagement of the apoptotic program in primary rodent islets relative to the INS-1 derived 832/13 cell line. As expected, 832/13 cells rapidly induced cell stress markers in response to ER stress or DNA damage and were fully committed to apoptosis, resulting in >80% cell death within 24 h. In contrast, primary rat islets were largely refractory to cell death in response to ER stress and DNA damage, despite rapid induction of stress markers, such as XBP-1(s), CHOP, and PUMA. Gene expression profiling revealed a general suppression of pro-apoptotic machinery, such as Apaf-1 and caspase 3, and sustained levels of pro-survival factors, such as cIAP-1, cIAP-2, and XIAP, in rat islets. Furthermore, we observed sustained induction of autophagy following chronic ER stress and found that inhibition of autophagy rendered islet β-cells highly vulnerable to ER stress-induced cell death. We propose that islet β-cells dampen the apoptotic response to delay the onset of cell death, providing a temporal window in which autophagy can be activated to limit cellular damage and promote survival.
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Affiliation(s)
- Heather L. Hayes
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Brett S. Peterson
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Jonathan M. Haldeman
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Christopher B. Newgard
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Medicine, Division of Endocrinology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Hans E. Hohmeier
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Medicine, Division of Endocrinology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Samuel B. Stephens
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, United States of America
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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20
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McManus MJ, Franklin JL. Dissociation of JNK Activation from Elevated Levels of Reactive Oxygen Species, Cytochrome c Release, and Cell Death in NGF-Deprived Sympathetic Neurons. Mol Neurobiol 2016; 55:382-389. [PMID: 27957682 DOI: 10.1007/s12035-016-0332-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 11/29/2016] [Indexed: 11/28/2022]
Abstract
Withdrawal of nerve growth factor (NGF) from sympathetic neurons causes their apoptotic death. Activation of c-Jun NH2-terminal kinase (JNK) may contribute to this death by the induction and phosphorylation of pro-apoptotic Bcl-2 proteins, such as Bax, that are involved in cytochrome c release from mitochondria and reactive oxygen species (ROS) production. Induction of either JNK or ROS may stimulate the other, and both may regulate release of apoptogenic factors from the mitochondria. In order to discern the relationship between JNK and ROS in apoptosis, we treated NGF-deprived, mouse sympathetic neurons with a JNK inhibitor and examined the effect on several important apoptotic events. Block of JNK activation prevented induction of c-Jun expression and resulted in a dose-dependent, yet surprisingly modest, increase in cell survival after 48 h of NGF deprivation. JNK suppression was also not sufficient to prevent the elevation in ROS or the release of cytochrome c from the mitochondria in NGF-deprived sympathetic neurons. Bax deletion prevents apoptotic death of NGF-deprived neurons by preventing release of cytochrome c from their mitochondria. It also prevents increased ROS on NGF deprivation. However, we found that induction of c-Jun in cells lacking Bax was equivalent to that in wild-type neurons. Our results suggest that while JNK activation plays an important role in many forms of apoptosis, it may not be a crucial regulator of Bax-dependent events involved in the apoptotic death of mouse sympathetic neurons deprived of NGF and that ROS is not involved in its activation in these cells.
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Affiliation(s)
- Meagan J McManus
- Center of Mitochondrial and Epigenomic Medicine, Children's Hospital of Philadelphia's Colket Translational Research Building, 3501 Civic Center Blvd, Room 6100, Philadelphia, PA, 19104, USA
| | - James L Franklin
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, 357 Wilson Pharmacy, Athens, GA, 30602, USA.
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21
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Kankeu C, Clarke K, Passante E, Huber HJ. Doxorubicin-induced chronic dilated cardiomyopathy-the apoptosis hypothesis revisited. J Mol Med (Berl) 2016; 95:239-248. [PMID: 27933370 DOI: 10.1007/s00109-016-1494-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 11/17/2016] [Accepted: 11/25/2016] [Indexed: 01/08/2023]
Abstract
The chemotherapeutic agent doxorubicin (DOX) has significantly increased survival rates of pediatric and adult cancer patients. However, 10% of pediatric cancer survivors will 10-20 years later develop severe dilated cardiomyopathy (DCM), whereby the exact molecular mechanisms of disease progression after this long latency time remain puzzling. We here revisit the hypothesis that elevated apoptosis signaling or its increased likelihood after DOX exposure can lead to an impairment of cardiac function and cause a cardiac dilation. Based on recent literature evidence, we first argue why a dilated phenotype can occur when little apoptosis is detected. We then review findings suggesting that mature cardiomyocytes are protected against DOX-induced apoptosis downstream, but not upstream of mitochondrial outer membrane permeabilisation (MOMP). This lack of MOMP induction is proposed to alter the metabolic phenotype, induce hypertrophic remodeling, and lead to functional cardiac impairment even in the absence of cardiomyocyte apoptosis. We discuss findings that DOX exposure can lead to increased sensitivity to further cardiomyocyte apoptosis, which may cause a gradual loss in cardiomyocytes over time and a compensatory hypertrophic remodeling after treatment, potentially explaining the long lag time in disease onset. We finally note similarities between DOX-exposed cardiomyocytes and apoptosis-primed cancer cells and propose computational system biology as a tool to predict patient individual DOX doses. In conclusion, combining recent findings in rodent hearts and cardiomyocytes exposed to DOX with insights from apoptosis signal transduction allowed us to obtain a molecularly deeper insight in this delayed and still enigmatic pathology of DCM.
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Affiliation(s)
- Cynthia Kankeu
- Department of Cardiovascular Sciences, KU Leuven, 3000, Leuven, Belgium
| | - Kylie Clarke
- Department of Cardiovascular Sciences, KU Leuven, 3000, Leuven, Belgium
| | - Egle Passante
- School of Pharmacy and Biomedical Sciences, Univ. of Central Lancashire, Preston, UK
| | - Heinrich J Huber
- Department of Cardiovascular Sciences, KU Leuven, 3000, Leuven, Belgium. .,Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, 123 St Stephens Green, Dublin 2, Ireland.
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22
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Annis RP, Swahari V, Nakamura A, Xie AX, Hammond SM, Deshmukh M. Mature neurons dynamically restrict apoptosis via redundant premitochondrial brakes. FEBS J 2016; 283:4569-4582. [PMID: 27797453 DOI: 10.1111/febs.13944] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 09/20/2016] [Accepted: 10/26/2016] [Indexed: 12/30/2022]
Abstract
Apoptotic cell death is critical for the early development of the nervous system, but once the nervous system is established, the apoptotic pathway becomes highly restricted in mature neurons. However, the mechanisms underlying this increased resistance to apoptosis in these mature neurons are not completely understood. We have previously found that members of the miR-29 family of microRNAs (miRNAs) are induced with neuronal maturation and that overexpression of miR-29 was sufficient to restrict apoptosis in neurons. To determine whether endogenous miR-29 alone was responsible for the inhibition of cytochrome c release in mature neurons, we examined the status of the apoptotic pathway in sympathetic neurons deficient for all three miR-29 family members. Unexpectedly, we found that the apoptotic pathway remained largely restricted in miR-29-deficient mature neurons. We therefore probed for additional mechanisms by which mature neurons resist apoptosis. We identify miR-24 as another miRNA that is upregulated in the maturing cerebellum and sympathetic neurons that can act redundantly with miR-29 by targeting a similar repertoire of prodeath BH3-only genes. Overall, our results reveal that mature neurons engage multiple redundant brakes to restrict the apoptotic pathway and ensure their long-term survival.
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Affiliation(s)
- Ryan P Annis
- Neuroscience Center, UNC Chapel Hill, NC, USA.,Curriculum in Neurobiology, UNC Chapel Hill, NC, USA
| | | | - Ayumi Nakamura
- Neuroscience Center, UNC Chapel Hill, NC, USA.,Curriculum in Neurobiology, UNC Chapel Hill, NC, USA
| | - Alison X Xie
- Department of Pharmacology, UNC Chapel Hill, NC, USA
| | - Scott M Hammond
- Department of Cell Biology and Physiology, UNC Chapel Hill, NC, USA
| | - Mohanish Deshmukh
- Neuroscience Center, UNC Chapel Hill, NC, USA.,Curriculum in Neurobiology, UNC Chapel Hill, NC, USA.,Department of Cell Biology and Physiology, UNC Chapel Hill, NC, USA
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23
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Axon degeneration: context defines distinct pathways. Curr Opin Neurobiol 2016; 39:108-15. [PMID: 27197022 DOI: 10.1016/j.conb.2016.05.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/02/2016] [Accepted: 05/03/2016] [Indexed: 12/29/2022]
Abstract
Axon degeneration is an essential part of development, plasticity, and injury response and has been primarily studied in mammalian models in three contexts: 1) Axotomy-induced Wallerian degeneration, 2) Apoptosis-induced axon degeneration (axon apoptosis), and 3) Axon pruning. These three contexts dictate engagement of distinct pathways for axon degeneration. Recent advances have identified the importance of SARM1, NMNATs, NAD+ depletion, and MAPK signaling in axotomy-induced Wallerian degeneration. Interestingly, apoptosis-induced axon degeneration and axon pruning have many shared mechanisms both in signaling (e.g. DLK, JNKs, GSK3α/β) and execution (e.g. Puma, Bax, caspase-9, caspase-3). However, the specific mechanisms by which caspases are activated during apoptosis versus pruning appear distinct, with apoptosis requiring Apaf-1 but not caspase-6 while pruning requires caspase-6 but not Apaf-1.
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24
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Lee JYC, Kuo CW, Tsai SL, Cheng SM, Chen SH, Chan HH, Lin CH, Lin KY, Li CF, Kanwar JR, Leung EY, Cheung CCH, Huang WJ, Wang YC, Cheung CHA. Inhibition of HDAC3- and HDAC6-Promoted Survivin Expression Plays an Important Role in SAHA-Induced Autophagy and Viability Reduction in Breast Cancer Cells. Front Pharmacol 2016; 7:81. [PMID: 27065869 PMCID: PMC4814469 DOI: 10.3389/fphar.2016.00081] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/14/2016] [Indexed: 11/13/2022] Open
Abstract
SAHA is a class I HDAC/HDAC6 co-inhibitor and an autophagy inducer currently undergoing clinical investigations in breast cancer patients. However, the molecular mechanism of action of SAHA in breast cancer cells remains unclear. In this study, we found that SAHA is equally effective in targeting cells of different breast cancer subtypes and tamoxifen sensitivity. Importantly, we found that down-regulation of survivin plays an important role in SAHA-induced autophagy and cell viability reduction in human breast cancer cells. SAHA decreased survivin and XIAP gene transcription, induced survivin protein acetylation and early nuclear translocation in MCF7 and MDA-MB-231 breast cancer cells. It also reduced survivin and XIAP protein stability in part through modulating the expression and activation of the 26S proteasome and heat-shock protein 90. Interestingly, targeting HDAC3 and HDAC6, but not other HDAC isoforms, by siRNA/pharmacological inhibitors mimicked the effects of SAHA in modulating the acetylation, expression, and nuclear translocation of survivin and induced autophagy in MCF7 and MDA-MB-231 cancer cells. Targeting HDAC3 also mimicked the effect of SAHA in up-regulating the expression and activity of proteasome, which might lead to the reduced protein stability of survivin in breast cancer cells. In conclusion, this study provides new insights into SAHA's molecular mechanism of actions in breast cancer cells. Our findings emphasize the complexity of the regulatory roles in different HDAC isoforms and potentially assist in predicting the mechanism of novel HDAC inhibitors in targeted or combinational therapies in the future.
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Affiliation(s)
- Jane Ying-Chieh Lee
- Department of Pharmacology, College of Medicine, National Cheng Kung University Tainan, Taiwan
| | - Ching-Wen Kuo
- Department of Pharmacology, College of Medicine, National Cheng Kung University Tainan, Taiwan
| | - Shing-Ling Tsai
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University Tainan, Taiwan
| | - Siao Muk Cheng
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University Tainan, Taiwan
| | - Shang-Hung Chen
- Division of Hematology and Oncology, Department of Internal Medicine, Chi-Mei Medical Center Liouying, Tainan, Taiwan
| | - Hsiu-Han Chan
- Department of Pharmacology, College of Medicine, National Cheng Kung University Tainan, Taiwan
| | - Chun-Hui Lin
- Department of Pharmacology, College of Medicine, National Cheng Kung University Tainan, Taiwan
| | - Kun-Yuan Lin
- Department of Pharmacology, College of Medicine, National Cheng Kung University Tainan, Taiwan
| | - Chien-Feng Li
- Department of Pathology, Chi-Mei Medical Center, Yung Kang District Tainan, Taiwan
| | - Jagat R Kanwar
- Nanomedicine-Laboratory of Immunology and Molecular Biology, Faculty of Health, School of Medicine, Deakin University Waurn Ponds, Geelong, VIC, Australia
| | - Euphemia Y Leung
- Auckland Cancer Society Research Centre and Department of Molecular Medicine and Pathology, University of Auckland Auckland, New Zealand
| | - Carlos Chun Ho Cheung
- School of Biological Sciences, Faculty of Science, University of Auckland Auckland, New Zealand
| | - Wei-Jan Huang
- Graduate Institute of Pharmacognosy, Taipei Medical University Taipei, Taiwan
| | - Yi-Ching Wang
- Department of Pharmacology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
| | - Chun Hei Antonio Cheung
- Department of Pharmacology, College of Medicine, National Cheng Kung UniversityTainan, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung UniversityTainan, Taiwan
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25
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Hoque A, Hossain MI, Ameen SS, Ang CS, Williamson N, Ng DCH, Chueh AC, Roulston C, Cheng HC. A beacon of hope in stroke therapy-Blockade of pathologically activated cellular events in excitotoxic neuronal death as potential neuroprotective strategies. Pharmacol Ther 2016; 160:159-79. [PMID: 26899498 DOI: 10.1016/j.pharmthera.2016.02.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Excitotoxicity, a pathological process caused by over-stimulation of ionotropic glutamate receptors, is a major cause of neuronal loss in acute and chronic neurological conditions such as ischaemic stroke, Alzheimer's and Huntington's diseases. Effective neuroprotective drugs to reduce excitotoxic neuronal loss in patients suffering from these neurological conditions are urgently needed. One avenue to achieve this goal is to clearly define the intracellular events mediating the neurotoxic signals originating from the over-stimulated glutamate receptors in neurons. In this review, we first focus on the key cellular events directing neuronal death but not involved in normal physiological processes in the neurotoxic signalling pathways. These events, referred to as pathologically activated events, are potential targets for the development of neuroprotectant therapeutics. Inhibitors blocking some of the known pathologically activated cellular events have been proven to be effective in reducing stroke-induced brain damage in animal models. Notable examples are inhibitors suppressing the ion channel activity of neurotoxic glutamate receptors and those disrupting interactions of specific cellular proteins occurring only in neurons undergoing excitotoxic cell death. Among them, Tat-NR2B9c and memantine are clinically effective in reducing brain damage caused by some acute and chronic neurological conditions. Our second focus is evaluation of the suitability of the other inhibitors for use as neuroprotective therapeutics. We also discuss the experimental approaches suitable for bridging our knowledge gap in our current understanding of the excitotoxic signalling mechanism in neurons and discovery of new pathologically activated cellular events as potential targets for neuroprotection.
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Affiliation(s)
- Ashfaqul Hoque
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - M Iqbal Hossain
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - S Sadia Ameen
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Ching-Seng Ang
- Bio21 Institute, University of Melbourne, Parkville, VIC 3010, Australia
| | | | - Dominic C H Ng
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia; School of Biomedical Science, University of Queensland, St. Lucia, QLD, Australia
| | - Anderly C Chueh
- ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3052, Australia
| | - Carli Roulston
- Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, VIC 3065, Australia
| | - Heung-Chin Cheng
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia.
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Jacob SF, Würstle ML, Delgado ME, Rehm M. An Analysis of the Truncated Bid- and ROS-dependent Spatial Propagation of Mitochondrial Permeabilization Waves during Apoptosis. J Biol Chem 2015; 291:4603-13. [PMID: 26699404 DOI: 10.1074/jbc.m115.689109] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Indexed: 01/07/2023] Open
Abstract
Apoptosis is a form of programmed cell death that is essential for the efficient elimination of surplus, damaged, and transformed cells during metazoan embryonic development and adult tissue homeostasis. Situated at the interface of apoptosis initiation and execution, mitochondrial outer membrane permeabilization (MOMP) represents one of the most fundamental processes during apoptosis signal transduction. It was shown that MOMP can spatiotemporally propagate through cells, in particular in response to extrinsic apoptosis induction. Based on apparently contradictory experimental evidence, two distinct molecular mechanisms have been proposed to underlie the propagation of MOMP signals, namely a reaction-diffusion mechanism governed by anisotropies in the production of the MOMP-inducer truncated Bid (tBid), or a process that drives the spatial propagation of MOMP by sequential bursts of reactive oxygen species. We therefore generated mathematical models for both scenarios and performed in silico simulations of spatiotemporal MOMP signaling to identify which one of the two mechanisms is capable of qualitatively and quantitatively reproducing the existing data. We found that the explanatory power of each model was limited in that only a subset of experimental findings could be replicated. However, the integration of both models into a combined mathematical description of spatiotemporal tBid and reactive oxygen species signaling accurately reproduced all available experimental data and furthermore, provided robustness to spatial MOMP propagation when mitochondria are spatially separated. Our study therefore provides a theoretical framework that is sufficient to describe and mechanistically explain the spatiotemporal propagation of one of the most fundamental processes during apoptotic cell death.
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Affiliation(s)
- Selma F Jacob
- From the Department of Physiology & Medical Physics and Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - Maximilian L Würstle
- From the Department of Physiology & Medical Physics and Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - M Eugenia Delgado
- From the Department of Physiology & Medical Physics and Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - Markus Rehm
- From the Department of Physiology & Medical Physics and Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin 2, Ireland
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27
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Abstract
The assembly of functional neural circuits requires the combined action of progressive and regressive events. Regressive events encompass a variety of inhibitory developmental processes, including axon and dendrite pruning, which facilitate the removal of exuberant neuronal connections. Most axon pruning involves the removal of axons that had already made synaptic connections; thus, axon pruning is tightly associated with synapse elimination. In many instances, these developmental processes are regulated by the interplay between neurons and glial cells that act instructively during neural remodeling. Owing to the importance of axon and dendritic pruning, these remodeling events require precise spatial and temporal control, and this is achieved by a range of distinct molecular mechanisms. Disruption of these mechanisms results in abnormal pruning, which has been linked to brain dysfunction. Therefore, understanding the mechanisms of axon and dendritic pruning will be instrumental in advancing our knowledge of neural disease and mental disorders.
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Affiliation(s)
- Martin M Riccomagno
- Department of Cell Biology and Neuroscience, University of California, Riverside, California 92521;
| | - Alex L Kolodkin
- Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205;
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28
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Abstract
Inhibitors of apoptosis (IAPs) family of genes encode baculovirus IAP-repeat domain-containing proteins with antiapoptotic function. These proteins also contain RING or UBC domains and act by binding to major proapoptotic factors and ubiquitylating them. High levels of IAPs inhibit caspase-mediated apoptosis. For these cells to undergo apoptosis, IAP function must be neutralized by IAP-antagonists. Mammalian IAP knockouts do not exhibit obvious developmental phenotypes, but the cells are more sensitized to apoptosis in response to injury. Loss of the mammalian IAP-antagonist ARTS results in reduced stem cell apoptosis. In addition to the antiapoptotic properties, IAPs regulate the innate immune response, and the loss of IAP function in humans is associated with immunodeficiency. The roles of IAPs in Drosophila apoptosis regulation are more apparent, where the loss of IAP1, or the expression of IAP-antagonists in Drosophila cells, is sufficient to trigger apoptosis. In this organism, apoptosis as a fate is conferred by the transcriptional induction of the IAP-antagonists. Many signaling pathways often converge on shared enhancer regions of IAP-antagonists. Cell death sensitivity is further regulated by posttranscriptional mechanisms, including those regulated by kinases, miRs, and ubiquitin ligases. These mechanisms are employed to eliminate damaged or virus-infected cells, limit neuroblast (neural stem cell) numbers, generate neuronal diversity, and sculpt tissue morphogenesis.
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Affiliation(s)
- Deepika Vasudevan
- Department of Cell Biology, New York University School of Medicine, New York, New York, USA
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, New York, USA.
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29
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Cell death in development: Signaling pathways and core mechanisms. Semin Cell Dev Biol 2015; 39:12-9. [PMID: 25668151 DOI: 10.1016/j.semcdb.2015.02.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/22/2015] [Accepted: 02/02/2015] [Indexed: 11/20/2022]
Abstract
Programmed cell death eliminates unneeded and dangerous cells in a timely and effective manner during development. In this review, we examine the role cell death plays during development in worms, flies and mammals. We discuss signaling pathways that regulate developmental cell death, and describe how they communicate with the core cell death pathways. In most organisms, the majority of developmental cell death is seen in the nervous system. Therefore we focus on what is known about the regulation of developmental cell death in this tissue. Understanding how the cell death is regulated during development may provide insight into how this process can be manipulated in the treatment of disease.
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30
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Elkholi R, Renault TT, Serasinghe MN, Chipuk JE. Putting the pieces together: How is the mitochondrial pathway of apoptosis regulated in cancer and chemotherapy? Cancer Metab 2014; 2:16. [PMID: 25621172 PMCID: PMC4304082 DOI: 10.1186/2049-3002-2-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 08/20/2014] [Indexed: 02/08/2023] Open
Abstract
In order to solve a jigsaw puzzle, one must first have the complete picture to logically connect the pieces. However, in cancer biology, we are still gaining an understanding of all the signaling pathways that promote tumorigenesis and how these pathways can be pharmacologically manipulated by conventional and targeted therapies. Despite not having complete knowledge of the mechanisms that cause cancer, the signaling networks responsible for cancer are becoming clearer, and this information is serving as a solid foundation for the development of rationally designed therapies. One goal of chemotherapy is to induce cancer cell death through the mitochondrial pathway of apoptosis. Within this review, we present the pathways that govern the cellular decision to undergo apoptosis as three distinct, yet connected puzzle pieces: (1) How do oncogene and tumor suppressor pathways regulate apoptosis upstream of mitochondria? (2) How does the B-cell lymphoma 2 (BCL-2) family influence tumorigenesis and chemotherapeutic responses? (3) How is post-mitochondrial outer membrane permeabilization (MOMP) regulation of cell death relevant in cancer? When these pieces are united, it is possible to appreciate how cancer signaling directly impacts upon the fundamental cellular mechanisms of apoptosis and potentially reveals novel pharmacological targets within these pathways that may enhance chemotherapeutic success.
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Affiliation(s)
- Rana Elkholi
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, 1425 Madison Avenue, Box 1130, New York, NY 10029, USA.,Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA
| | - Thibaud T Renault
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, 1425 Madison Avenue, Box 1130, New York, NY 10029, USA.,Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA
| | - Madhavika N Serasinghe
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, 1425 Madison Avenue, Box 1130, New York, NY 10029, USA.,Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA
| | - Jerry E Chipuk
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, 1425 Madison Avenue, Box 1130, New York, NY 10029, USA.,Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.,The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA
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31
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Neukomm LJ, Freeman MR. Diverse cellular and molecular modes of axon degeneration. Trends Cell Biol 2014; 24:515-23. [PMID: 24780172 PMCID: PMC4149811 DOI: 10.1016/j.tcb.2014.04.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 03/30/2014] [Accepted: 04/01/2014] [Indexed: 01/11/2023]
Abstract
The elimination of large portions of axons is a widespread event in the developing and diseased nervous system. Subsets of axons are selectively destroyed to help fine-tune neural circuit connectivity during development. Axonal degeneration is also an early feature of nearly all neurodegenerative diseases, occurs after most neural injuries, and is a primary driver of functional impairment in patients. In this review we discuss the diversity of cellular mechanisms by which axons degenerate. Initial molecular characterization highlights some similarities in their execution but also argues that unique genetic programs modulate each mode of degeneration. Defining these pathways rigorously will provide new targets for therapeutic intervention after neural injury or in neurodegenerative disease.
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Affiliation(s)
- Lukas J Neukomm
- Department of Neurobiology, Howard Hughes Medical Institute, University of Massachusetts Medical School, 704 LRB, 364 Plantation Street, Worcester, MA 01609, USA
| | - Marc R Freeman
- Department of Neurobiology, Howard Hughes Medical Institute, University of Massachusetts Medical School, 704 LRB, 364 Plantation Street, Worcester, MA 01609, USA.
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32
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Gama V, Swahari V, Schafer J, Kole AJ, Evans A, Huang Y, Cliffe A, Golitz B, Sciaky N, Pei XH, Xiong Y, Deshmukh M. The E3 ligase PARC mediates the degradation of cytosolic cytochrome c to promote survival in neurons and cancer cells. Sci Signal 2014; 7:ra67. [PMID: 25028717 DOI: 10.1126/scisignal.2005309] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The ability to withstand mitochondrial damage is especially critical for the survival of postmitotic cells, such as neurons. Likewise, cancer cells can also survive mitochondrial stress. We found that cytochrome c (Cyt c), which induces apoptosis upon its release from damaged mitochondria, is targeted for proteasome-mediated degradation in mouse neurons, cardiomyocytes, and myotubes and in human glioma and neuroblastoma cells, but not in proliferating human fibroblasts. In mouse neurons, apoptotic protease-activating factor 1 (Apaf-1) prevented the proteasome-dependent degradation of Cyt c in response to induced mitochondrial stress. An RNA interference screen in U-87 MG glioma cells identified p53-associated Parkin-like cytoplasmic protein (PARC, also known as CUL9) as an E3 ligase that targets Cyt c for degradation. The abundance of PARC positively correlated with differentiation in mouse neurons, and overexpression of PARC reduced the abundance of mitochondrially-released cytosolic Cyt c in various cancer cell lines and in mouse embryonic fibroblasts. Conversely, neurons from Parc-deficient mice had increased sensitivity to mitochondrial damage, and neuroblastoma or glioma cells in which PARC or ubiquitin was knocked down had increased abundance of mitochondrially-released cytosolic Cyt c and decreased viability in response to stress. These findings suggest that PARC-mediated ubiquitination and degradation of Cyt c is a strategy engaged by both neurons and cancer cells to prevent apoptosis during conditions of mitochondrial stress.
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Affiliation(s)
- Vivian Gama
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA. Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Vijay Swahari
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA. Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Johanna Schafer
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Adam J Kole
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Allyson Evans
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Yolanda Huang
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Anna Cliffe
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA. Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Brian Golitz
- UNC RNAi Screening Facility, University of North Carolina, Chapel Hill, NC 27599, USA. Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Noah Sciaky
- UNC RNAi Screening Facility, University of North Carolina, Chapel Hill, NC 27599, USA. Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Xin-Hai Pei
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA. Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Yue Xiong
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA. Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Mohanish Deshmukh
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA. Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA. Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
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33
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Endogenous XIAP, but not other members of the inhibitory apoptosis protein family modulates cerebellar granule neurons survival. Int J Dev Neurosci 2014; 37:26-35. [PMID: 24955869 DOI: 10.1016/j.ijdevneu.2014.06.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 06/15/2014] [Accepted: 06/15/2014] [Indexed: 02/05/2023] Open
Abstract
Programmed cell death plays a critical role during cerebellar development. In particular, it has been shown in vivo and in vitro that developing cerebellar granule neurons (CGN) die apoptotically. Apoptosis involves a series of morphological changes and the activation of caspases. Inhibitor of apoptosis proteins (IAPs) is implicated in negative regulation of caspase activation and apoptotic cell death. Although apoptotic death of CGN has been extensively studied, there is no information about the role of IAPs in the developing cerebellum. Here, we studied the participation of some members of IAPs in the survival of the developing rat CGN in culture and under physiological conditions. Under these conditions, we found a differential expression pattern of cIAP-1, cIAP-2, XIAP and survivin during cerebellar development in an age-dependent manner, highlighting the significant increase of XIAP levels. We also detected an interaction between XIAP and caspase 3 at postnatal day (P) 12 and 16. On the other hand, we found a significant decrease of XIAP levels in cultured CGN maintained in chronic potassium deprivation, an apoptotic condition, suggesting a possible relationship between XIAP levels and neuronal viability. Under these conditions, we also detected the interaction of XIAP with active caspase-3. The down-regulation of XIAP in CGN cultured under survival conditions (chronic potassium depolarization) induced a reduction of cell viability and an increment of apoptotic cells. These findings support the idea that IAPs could be involved in the survival of CGN and that XIAP might be critical for neuronal survival in cerebellar development and during chronic depolarization in cultured CGN through a mechanism involving caspase inhibition.
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34
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Würstle ML, Zink E, Prehn JHM, Rehm M. From computational modelling of the intrinsic apoptosis pathway to a systems-based analysis of chemotherapy resistance: achievements, perspectives and challenges in systems medicine. Cell Death Dis 2014; 5:e1258. [PMID: 24874730 PMCID: PMC4047923 DOI: 10.1038/cddis.2014.36] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 12/20/2013] [Accepted: 01/02/2014] [Indexed: 12/14/2022]
Abstract
Our understanding of the mitochondrial or intrinsic apoptosis pathway and its role in chemotherapy resistance has increased significantly in recent years by a combination of experimental studies and mathematical modelling. This combined approach enhanced the quantitative and kinetic understanding of apoptosis signal transduction, but also provided new insights that systems-emanating functions (i.e., functions that cannot be attributed to individual network components but that are instead established by multi-component interplay) are crucial determinants of cell fate decisions. Among these features are molecular thresholds, cooperative protein functions, feedback loops and functional redundancies that provide systems robustness, and signalling topologies that allow ultrasensitivity or switch-like responses. The successful development of kinetic systems models that recapitulate biological signal transduction observed in living cells have now led to the first translational studies, which have exploited and validated such models in a clinical context. Bottom-up strategies that use pathway models in combination with higher-level modelling at the tissue, organ and whole body-level therefore carry great potential to eventually deliver a new generation of systems-based diagnostic tools that may contribute to the development of personalised and predictive medicine approaches. Here we review major achievements in the systems biology of intrinsic apoptosis signalling, discuss challenges for further model development, perspectives for higher-level integration of apoptosis models and finally discuss requirements for the development of systems medical solutions in the coming years.
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Affiliation(s)
- M L Würstle
- 1] Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland [2] Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - E Zink
- 1] Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland [2] Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - J H M Prehn
- 1] Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland [2] Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - M Rehm
- 1] Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland [2] Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
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35
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Milanović D, Pešić V, Popić J, Tanić N, Kanazir S, Jevtović-Todorović V, Ruždijić S. Propofol anesthesia induces proapoptotic tumor necrosis factor-α and pro-nerve growth factor signaling and prosurvival Akt and XIAP expression in neonatal rat brain. J Neurosci Res 2014; 92:1362-73. [PMID: 24827783 DOI: 10.1002/jnr.23409] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/27/2014] [Accepted: 04/08/2014] [Indexed: 11/12/2022]
Abstract
Previously we observed that prolonged exposure to propofol anesthesia causes caspase-3- and calpain-mediated neuronal death in the developing brain. The present study examines the effects of propofol anesthesia on the expression of tumor necrosis factor-α (TNFα), pro-nerve growth factor (NGF), and their receptors in the cortex and the thalamus. We also investigated how propofol influences the expression of Akt and X-linked inhibitor of apoptosis (XIAP) expression, proteins that promote prosurvival pathways. Seven-day-old rats (P7) were exposed to propofol anesthesia lasting 2, 4, or 6 hr and killed 0, 4, 16, or 24 hr after anesthesia termination. The relative levels of mRNA and protein expression were estimated by RT-PCR and Western blot analysis, respectively. The treatments caused marked activation of TNFα and its receptor TNFR-1 and pro-NGF and p75(NTR) receptor expression. In parallel with the induction of these prodeath signals, we established that propofol anesthesia promotes increased expression of the prosurvival molecules pAkt and XIAP during the 24-hr postanesthesia period. These results show that different brain structures respond to propofol anesthesia with a time- and duration of exposure-dependent increase in proapoptotic signaling and with concomitant increases in activities of prosurvival proteins. We hypothesized that the fine balance between these opposing processes sustains homeostasis in the immature rat brain and prevents unnecessary damage after exposure to an injurious stimulus. The existence of this highly regulated process provides a time frame for potential therapeutic intervention directed toward suppressing the deleterious component of propofol anesthesia.
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Affiliation(s)
- Desanka Milanović
- Department of Neurobiology, Institute for Biological Research, University of Belgrade, Belgrade, Republic of Serbia
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36
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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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37
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Kristiansen M, Ham J. Programmed cell death during neuronal development: the sympathetic neuron model. Cell Death Differ 2014; 21:1025-35. [PMID: 24769728 PMCID: PMC4207485 DOI: 10.1038/cdd.2014.47] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 03/05/2014] [Accepted: 03/13/2014] [Indexed: 01/08/2023] Open
Abstract
Developing sympathetic neurons of the superior cervical ganglion are one of the best studied models of neuronal apoptosis. These cells require nerve growth factor (NGF) for survival at the time that they innervate their final target tissues during late embryonic and early postnatal development. In the absence of NGF, developing sympathetic neurons die by apoptosis in a transcription-dependent manner. Molecular studies of sympathetic neuron apoptosis began in the 1980s. We now know that NGF withdrawal activates the mitochondrial (intrinsic) pathway of apoptosis in sympathetic neurons cultured in vitro, and the roles of caspases, Bcl-2 (B-cell CLL/lymphoma 2) family proteins and XIAP (X-linked inhibitor of apoptosis protein) have been extensively studied. Importantly, a considerable amount has also been learned about the intracellular signalling pathways and transcription factors that regulate programmed cell death in sympathetic neurons. In this article, we review the key papers published in the past few years, covering all aspects of apoptosis regulation in sympathetic neurons and focusing, in particular, on how signalling pathways and transcription factors regulate the cell death programme. We make some comparisons with other models of neuronal apoptosis and describe possible future directions for the field.
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Affiliation(s)
- M Kristiansen
- Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - J Ham
- Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
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38
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Abstract
KIF1B is a candidate tumor-suppressor gene in neuroblastoma whose function is to mediate apoptosis when nerve growth factor becomes limiting in the developing nervous system. Chen and colleagues now provide mechanistic insight into how one of the protein products of this locus, KIF1Bβ, induces apoptosis.
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Affiliation(s)
- Rene Bernards
- Division of Molecular Carcinogenesis and Cancer Genomics Centre Netherlands, The Netherlands Cancer Institute, Amsterdam, the Netherlands
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39
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FAIM-L is an IAP-binding protein that inhibits XIAP ubiquitinylation and protects from Fas-induced apoptosis. J Neurosci 2014; 33:19262-75. [PMID: 24305822 DOI: 10.1523/jneurosci.2479-13.2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The neuronal long isoform of Fas Apoptotic Inhibitory Molecule (FAIM-L) protects from death receptor (DR)-induced apoptosis, yet its mechanism of protection remains unknown. Here, we show that FAIM-L protects rat neuronal Type II cells from Fas-induced apoptosis. XIAP has previously emerged as a molecular discriminator that is upregulated in Type II and downregulated in Type I apoptotic signaling. We demonstrate that FAIM-L requires sustained endogenous levels of XIAP to protect Type II cells as well as murine cortical neurons from Fas-induced apoptosis. FAIM-L interacts with the BIR2 domain of XIAP through an IAP-binding motif, the mutation of which impairs the antiapoptotic function of FAIM-L. Finally, we report that FAIM-L inhibits XIAP auto-ubiquitinylation and maintains its stability, thus conferring protection from apoptosis. Our results bring new understanding of the regulation of endogenous XIAP by a DR antagonist, pointing out at FAIM-L as a promising therapeutic tool for protection from apoptosis in pathological situations where XIAP levels are decreased.
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40
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Chen ZX, Wallis K, Fell SM, Sobrado VR, Hemmer MC, Ramsköld D, Hellman U, Sandberg R, Kenchappa RS, Martinson T, Johnsen JI, Kogner P, Schlisio S. RNA helicase A is a downstream mediator of KIF1Bβ tumor-suppressor function in neuroblastoma. Cancer Discov 2014; 4:434-51. [PMID: 24469107 DOI: 10.1158/2159-8290.cd-13-0362] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
UNLABELLED Inherited KIF1B loss-of-function mutations in neuroblastomas and pheochromocytomas implicate the kinesin KIF1B as a 1p36.2 tumor suppressor. However, the mechanism of tumor suppression is unknown. We found that KIF1B isoform β (KIF1Bβ) interacts with RNA helicase A (DHX9), causing nuclear accumulation of DHX9, followed by subsequent induction of the proapoptotic XIAP-associated factor 1 (XAF1) and, consequently, apoptosis. Pheochromocytoma and neuroblastoma arise from neural crest progenitors that compete for growth factors such as nerve growth factor (NGF) during development. KIF1Bβ is required for developmental apoptosis induced by competition for NGF. We show that DHX9 is induced by and required for apoptosis stimulated by NGF deprivation. Moreover, neuroblastomas with chromosomal deletion of 1p36 exhibit loss of KIF1Bβ expression and impaired DHX9 nuclear localization, implicating the loss of DHX9 nuclear activity in neuroblastoma pathogenesis. SIGNIFICANCE KIF1Bβ has neuroblastoma tumor-suppressor properties and promotes and requires nuclear-localized DHX9 for its apoptotic function by activating XAF1 expression. Loss of KIF1Bβ alters subcellular localization of DHX9 and diminishes NGF dependence of sympathetic neurons, leading to reduced culling of neural progenitors, and, therefore, might predispose to tumor formation.
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Affiliation(s)
- Zhi Xiong Chen
- 1Ludwig Institute for Cancer Research Ltd.; 2Department of Cell and Molecular Biology, Karolinska Institutet; 3Department of Women's and Children's Health, Karolinska University Hospital, Stockholm; 4Ludwig Institute for Cancer Research Ltd., Biomedical Center, Uppsala; 5Department of Clinical Genetics, Institute of Biomedicine, University of Gothenburg, Sahlgrenska University Hospital, Göteborg, Sweden; and 6Moffitt Cancer Center, Neuro-Oncology Program, Tampa, Florida
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41
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Kraemer BR, Yoon SO, Carter BD. The biological functions and signaling mechanisms of the p75 neurotrophin receptor. Handb Exp Pharmacol 2014; 220:121-164. [PMID: 24668472 DOI: 10.1007/978-3-642-45106-5_6] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The p75 neurotrophin receptor (p75(NTR)) regulates a wide range of cellular functions, including programmed cell death, axonal growth and degeneration, cell proliferation, myelination, and synaptic plasticity. The multiplicity of cellular functions governed by the receptor arises from the variety of ligands and co-receptors which associate with p75(NTR) and regulate its signaling. P75(NTR) promotes survival through interactions with Trk receptors, inhibits axonal regeneration via partnerships with Nogo receptor (Nogo-R) and Lingo-1, and promotes apoptosis through association with Sortilin. Signals downstream of these interactions are further modulated through regulated intramembrane proteolysis (RIP) of p75(NTR) and by interactions with numerous cytosolic partners. In this chapter, we discuss the intricate signaling mechanisms of p75(NTR), emphasizing how these signals are differentially regulated to mediate these diverse cellular functions.
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Affiliation(s)
- B R Kraemer
- Department of Biochemistry, Vanderbilt University School of Medicine, 625 Light Hall, Nashville, TN, 37232, USA
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42
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Fiedler LR, Maifoshie E, Schneider MD. Mouse models of heart failure: cell signaling and cell survival. Curr Top Dev Biol 2014; 109:171-247. [PMID: 24947238 DOI: 10.1016/b978-0-12-397920-9.00002-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Heart failure is one of the paramount global causes of morbidity and mortality. Despite this pandemic need, the available clinical counter-measures have not altered substantially in recent decades, most notably in the context of pharmacological interventions. Cell death plays a causal role in heart failure, and its inhibition poses a promising approach that has not been thoroughly explored. In previous approaches to target discovery, clinical failures have reflected a deficiency in mechanistic understanding, and in some instances, failure to systematically translate laboratory findings toward the clinic. Here, we review diverse mouse models of heart failure, with an emphasis on those that identify potential targets for pharmacological inhibition of cell death, and on how their translation into effective therapies might be improved in the future.
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Affiliation(s)
- Lorna R Fiedler
- British Heart Foundation Centre of Research Excellence, National Heart and Lung Institute, Imperial College London, London, UK.
| | - Evie Maifoshie
- British Heart Foundation Centre of Research Excellence, National Heart and Lung Institute, Imperial College London, London, UK
| | - Michael D Schneider
- British Heart Foundation Centre of Research Excellence, National Heart and Lung Institute, Imperial College London, London, UK.
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43
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Cusack CL, Swahari V, Hampton Henley W, Michael Ramsey J, Deshmukh M. Distinct pathways mediate axon degeneration during apoptosis and axon-specific pruning. Nat Commun 2013; 4:1876. [PMID: 23695670 PMCID: PMC4183061 DOI: 10.1038/ncomms2910] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/18/2013] [Indexed: 12/13/2022] Open
Abstract
Neurons can activate pathways that destroy the whole cell via apoptosis or selectively degenerate only the axon (pruning). Both apoptosis and axon degeneration require Bax and caspases. Here we demonstrate that despite this overlap, the pathways mediating axon degeneration during apoptosis versus axon pruning are distinct. While caspase-6 is activated in axons following nerve growth factor (NGF) deprivation, microfluidic chamber experiments reveal that caspase-6 deficiency only protects axons during axon-specific but not whole-cell (apoptotic) NGF deprivation. Strikingly, axon-selective degeneration requires the apoptotic proteins Caspase-9 and Caspase-3 but, in contrast to apoptosis, not Apaf-1. Additionally, cell bodies of degenerating axons are protected from caspase activation by protea some activity and XIAP. Also, mature neurons restrict apoptosis but remain permissive for axon degeneration, further demonstrating the independent regulation of these two pathways. These results reveal insight into how neurons allow for precise control over apoptosis and axon-selective degeneration pathways, thereby permitting long-term plasticity without risking neurodegeneration.
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Affiliation(s)
- Corey L Cusack
- Neurobiology Curriculum, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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44
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Tait SWG, Green DR. Mitochondrial regulation of cell death. Cold Spring Harb Perspect Biol 2013; 5:5/9/a008706. [PMID: 24003207 DOI: 10.1101/cshperspect.a008706] [Citation(s) in RCA: 340] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although required for life, paradoxically, mitochondria are often essential for initiating apoptotic cell death. Mitochondria regulate caspase activation and cell death through an event termed mitochondrial outer membrane permeabilization (MOMP); this leads to the release of various mitochondrial intermembrane space proteins that activate caspases, resulting in apoptosis. MOMP is often considered a point of no return because it typically leads to cell death, even in the absence of caspase activity. Because of this pivotal role in deciding cell fate, deregulation of MOMP impacts on many diseases and represents a fruitful site for therapeutic intervention. Here we discuss the mechanisms underlying mitochondrial permeabilization and how this key event leads to cell death through caspase-dependent and -independent means. We then proceed to explore how the release of mitochondrial proteins may be regulated following MOMP. Finally, we discuss mechanisms that enable cells sometimes to survive MOMP, allowing them, in essence, to return from the point of no return.
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Affiliation(s)
- Stephen W G Tait
- Beatson Institute, Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1BD, United Kingdom.
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45
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Unsain N, Higgins JM, Parker KN, Johnstone AD, Barker PA. XIAP Regulates Caspase Activity in Degenerating Axons. Cell Rep 2013; 4:751-63. [PMID: 23954782 DOI: 10.1016/j.celrep.2013.07.015] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 04/11/2013] [Accepted: 07/11/2013] [Indexed: 11/16/2022] Open
Affiliation(s)
- Nicolas Unsain
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec H3A 2B4, Canada
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46
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Ooi HK, Ma L. Modeling heterogeneous responsiveness of intrinsic apoptosis pathway. BMC SYSTEMS BIOLOGY 2013; 7:65. [PMID: 23875784 PMCID: PMC3733900 DOI: 10.1186/1752-0509-7-65] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 07/19/2013] [Indexed: 12/22/2022]
Abstract
BACKGROUND Apoptosis is a cell suicide mechanism that enables multicellular organisms to maintain homeostasis and to eliminate individual cells that threaten the organism's survival. Dependent on the type of stimulus, apoptosis can be propagated by extrinsic pathway or intrinsic pathway. The comprehensive understanding of the molecular mechanism of apoptotic signaling allows for development of mathematical models, aiming to elucidate dynamical and systems properties of apoptotic signaling networks. There have been extensive efforts in modeling deterministic apoptosis network accounting for average behavior of a population of cells. Cellular networks, however, are inherently stochastic and significant cell-to-cell variability in apoptosis response has been observed at single cell level. RESULTS To address the inevitable randomness in the intrinsic apoptosis mechanism, we develop a theoretical and computational modeling framework of intrinsic apoptosis pathway at single-cell level, accounting for both deterministic and stochastic behavior. Our deterministic model, adapted from the well-accepted Fussenegger model, shows that an additional positive feedback between the executioner caspase and the initiator caspase plays a fundamental role in yielding the desired property of bistability. We then examine the impact of intrinsic fluctuations of biochemical reactions, viewed as intrinsic noise, and natural variation of protein concentrations, viewed as extrinsic noise, on behavior of the intrinsic apoptosis network. Histograms of the steady-state output at varying input levels show that the intrinsic noise could elicit a wider region of bistability over that of the deterministic model. However, the system stochasticity due to intrinsic fluctuations, such as the noise of steady-state response and the randomness of response delay, shows that the intrinsic noise in general is insufficient to produce significant cell-to-cell variations at physiologically relevant level of molecular numbers. Furthermore, the extrinsic noise represented by random variations of two key apoptotic proteins, namely Cytochrome C and inhibitor of apoptosis proteins (IAP), is modeled separately or in combination with intrinsic noise. The resultant stochasticity in the timing of intrinsic apoptosis response shows that the fluctuating protein variations can induce cell-to-cell stochastic variability at a quantitative level agreeing with experiments. Finally, simulations illustrate that the mean abundance of fluctuating IAP protein is positively correlated with the degree of cellular stochasticity of the intrinsic apoptosis pathway. CONCLUSIONS Our theoretical and computational study shows that the pronounced non-genetic heterogeneity in intrinsic apoptosis responses among individual cells plausibly arises from extrinsic rather than intrinsic origin of fluctuations. In addition, it predicts that the IAP protein could serve as a potential therapeutic target for suppression of the cell-to-cell variation in the intrinsic apoptosis responsiveness.
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Affiliation(s)
- Hsu Kiang Ooi
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080, USA
| | - Lan Ma
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080, USA
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47
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LaCasse EC. Pulling the plug on a cancer cell by eliminating XIAP with AEG35156. Cancer Lett 2012; 332:215-24. [PMID: 22776562 DOI: 10.1016/j.canlet.2012.06.015] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 06/28/2012] [Accepted: 06/30/2012] [Indexed: 12/22/2022]
Abstract
XIAP, the X-linked inhibitor of apoptosis, is the best example of an endogenous cellular suppressor of apoptosis. XIAP is effective because it directly limits the activity of several critical death-inducing caspases, notably caspase-3, -7 and -9, either by direct enzyme inhibition or through ubiquitin-mediated proteasomal degradation. Furthermore, XIAP acts simultaneously at several nodes in the apoptotic cascade, blocking both the intrinsic and extrinsic death pathways, and thereby preventing feed-forward amplification loops that would otherwise lead to cell death. XIAP over-expression, or increased activity, is associated with cancer progression, resistance to therapy and poor prognosis. Targeting XIAP gene expression by antisense oligonucleotides, or other approaches, demonstrates anti-cancer effects with XIAP down-regulation. These early preclinical studies led to the development of a clinical candidate mixed-backbone antisense oligonucleotide, AEG35156, against XIAP for the treatment of cancer. Published clinical results for the first-in-class and first-in-human trials of AEG35156 are summarized herein, including single agent and combination chemotherapy phase-I or -II trials for solid tumors, lymphoma, and acute myeloid leukemia. These trials demonstrate the safety of AEG35156, as well as some initial promising signs of anti-cancer activity.
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Affiliation(s)
- Eric C LaCasse
- Apoptosis Research Centre, CHEO RI2, Children's Hospital of Eastern Ontario, 401 Smyth Rd., Ottawa, ON, Canada K1H 8L1.
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48
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Uribe V, Wong BK, Graham RK, Cusack CL, Skotte NH, Pouladi MA, Xie Y, Feinberg K, Ou Y, Ouyang Y, Deng Y, Franciosi S, Bissada N, Spreeuw A, Zhang W, Ehrnhoefer DE, Vaid K, Miller FD, Deshmukh M, Howland D, Hayden MR. Rescue from excitotoxicity and axonal degeneration accompanied by age-dependent behavioral and neuroanatomical alterations in caspase-6-deficient mice. Hum Mol Genet 2012; 21:1954-67. [PMID: 22262731 PMCID: PMC3315204 DOI: 10.1093/hmg/dds005] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 01/09/2012] [Indexed: 11/13/2022] Open
Abstract
Apoptosis, or programmed cell death, is a cellular pathway involved in normal cell turnover, developmental tissue remodeling, embryonic development, cellular homeostasis maintenance and chemical-induced cell death. Caspases are a family of intracellular proteases that play a key role in apoptosis. Aberrant activation of caspases has been implicated in human diseases. In particular, numerous findings implicate Caspase-6 (Casp6) in neurodegenerative diseases, including Alzheimer disease (AD) and Huntington disease (HD), highlighting the need for a deeper understanding of Casp6 biology and its role in brain development. The use of targeted caspase-deficient mice has been instrumental for studying the involvement of caspases in apoptosis. The goal of this study was to perform an in-depth neuroanatomical and behavioral characterization of constitutive Casp6-deficient (Casp6-/-) mice in order to understand the physiological function of Casp6 in brain development, structure and function. We demonstrate that Casp6-/- neurons are protected against excitotoxicity, nerve growth factor deprivation and myelin-induced axonal degeneration. Furthermore, Casp6-deficient mice show an age-dependent increase in cortical and striatal volume. In addition, these mice show a hypoactive phenotype and display learning deficits. The age-dependent behavioral and region-specific neuroanatomical changes observed in the Casp6-/- mice suggest that Casp6 deficiency has a more pronounced effect in brain regions that are involved in neurodegenerative diseases, such as the striatum in HD and the cortex in AD.
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Affiliation(s)
- Valeria Uribe
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Bibiana K.Y. Wong
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Rona K. Graham
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Corey L. Cusack
- Department of Cell and Developmental Biology and Neuroscience Center, University of North Carolina, Chapel Hill, NC27599-7250, USA
| | - Niels H. Skotte
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
- Department of Medical Genetics, Institute of Cellular and Molecular Medicine, University of Copenhagen, 2200 N Copenhagen, Denmark
| | - Mahmoud A. Pouladi
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Yuanyun Xie
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Konstantin Feinberg
- Developmental and Stem Cell Biology Group, Hospital for Sick Children, Toronto, OntarioM5G1L7, Canada
| | - Yimiao Ou
- Developmental and Stem Cell Biology Group, Hospital for Sick Children, Toronto, OntarioM5G1L7, Canada
| | | | - Yu Deng
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Sonia Franciosi
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Nagat Bissada
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Amanda Spreeuw
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Weining Zhang
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Dagmar E. Ehrnhoefer
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Kuljeet Vaid
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - Freda D. Miller
- Developmental and Stem Cell Biology Group, Hospital for Sick Children, Toronto, OntarioM5G1L7, Canada
- Department of Molecular Genetics and
- Department of Physiology, University of Toronto, Toronto, OntarioM5G1X5, Canada
| | - Mohanish Deshmukh
- Department of Cell and Developmental Biology and Neuroscience Center, University of North Carolina, Chapel Hill, NC27599-7250, USA
| | | | - Michael R. Hayden
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
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49
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Abstract
Excitotoxicity resulting from excessive Ca(2+) influx through glutamate receptors contributes to neuronal injury after stroke, trauma, and seizures. Increased cytosolic Ca(2+) levels activate a family of calcium-dependent proteases with papain-like activity, the calpains. Here we investigated the role of calpain activation during NMDA-induced excitotoxic injury in embryonic (E16-E18) murine cortical neurons that (1) underwent excitotoxic necrosis, characterized by immediate deregulation of Ca(2+) homeostasis, a persistent depolarization of mitochondrial membrane potential (Δψ(m)), and insensitivity to bax-gene deletion, (2) underwent excitotoxic apoptosis, characterized by recovery of NMDA-induced cytosolic Ca(2+) increases, sensitivity to bax gene deletion, and delayed Δψ(m) depolarization and Ca(2+) deregulation, or (3) that were tolerant to excitotoxic injury. Interestingly, treatment with the calpain inhibitor calpeptin, overexpression of the endogenous calpain inhibitor calpastatin, or gene silencing of calpain protected neurons against excitotoxic apoptosis but did not influence excitotoxic necrosis. Calpeptin failed to exert a protective effect in bax-deficient neurons but protected bid-deficient neurons similarly to wild-type cells. To identify when calpains became activated during excitotoxic apoptosis, we monitored calpain activation dynamics by time-lapse fluorescence microscopy using a calpain-sensitive Förster resonance energy transfer probe. We observed a delayed calpain activation that occurred downstream of mitochondrial engagement and directly preceded neuronal death. In contrast, we could not detect significant calpain activity during excitotoxic necrosis or in neurons that were tolerant to excitotoxic injury. Oxygen/glucose deprivation-induced injury in organotypic hippocampal slice cultures confirmed that calpains were specifically activated during bax-dependent apoptosis and in this setting function as downstream cell-death executioners.
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50
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Würstle ML, Laussmann MA, Rehm M. The central role of initiator caspase-9 in apoptosis signal transduction and the regulation of its activation and activity on the apoptosome. Exp Cell Res 2012; 318:1213-20. [PMID: 22406265 DOI: 10.1016/j.yexcr.2012.02.013] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 02/16/2012] [Accepted: 02/16/2012] [Indexed: 10/28/2022]
Abstract
Key structural and catalytic features are conserved across the entire family of cysteine-dependent aspartate-specific proteases (caspases). Of the caspases involved in apoptosis signal transduction, the initiator caspases-2, -8 and -9 are activated at multi-protein activation platforms, and activation is thought to involve homo-dimerisation of the monomeric zymogens. Caspase-9, the essential initiator caspase required for apoptosis signalling through the mitochondrial pathway, is activated on the apoptosome complex, and failure to activate caspase-9 has profound pathophysiological consequences. Here, we review the pertinent literature on which the currently prevalent understanding of caspase-9 activation is based, extend this view by insight obtained from recent structural and kinetic studies on caspase-9 signalling, and describe an emerging model for the regulation of caspase-9 activation and activity that arise from the complexity of multi-protein interactions at the apoptosome. This integrated view allows us to postulate and to discuss functional consequences for caspase-9 activation and apoptosis execution that may take centre stage in future experimental cell research on apoptosis signalling.
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Affiliation(s)
- Maximilian L Würstle
- Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin 2, Ireland
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