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Killing by Degradation: Regulation of Apoptosis by the Ubiquitin-Proteasome-System. Cells 2021; 10:cells10123465. [PMID: 34943974 PMCID: PMC8700063 DOI: 10.3390/cells10123465] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 12/13/2022] Open
Abstract
Apoptosis is a cell suicide process that is essential for development, tissue homeostasis and human health. Impaired apoptosis is associated with a variety of human diseases, including neurodegenerative disorders, autoimmunity and cancer. As the levels of pro- and anti-apoptotic proteins can determine the life or death of cells, tight regulation of these proteins is critical. The ubiquitin proteasome system (UPS) is essential for maintaining protein turnover, which can either trigger or inhibit apoptosis. In this review, we will describe the E3 ligases that regulate the levels of pro- and anti-apoptotic proteins and assisting proteins that regulate the levels of these E3 ligases. We will provide examples of apoptotic cell death modulations using the UPS, determined by positive and negative feedback loop reactions. Specifically, we will review how the stability of p53, Bcl-2 family members and IAPs (Inhibitor of Apoptosis proteins) are regulated upon initiation of apoptosis. As increased levels of oncogenes and decreased levels of tumor suppressor proteins can promote tumorigenesis, targeting these pathways offers opportunities to develop novel anti-cancer therapies, which act by recruiting the UPS for the effective and selective killing of cancer cells.
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Hsu YL, Hung HS, Tsai CW, Liu SP, Chiang YT, Kuo YH, Shyu WC, Lin SZ, Fu RH. Peiminine Reduces ARTS-Mediated Degradation of XIAP by Modulating the PINK1/Parkin Pathway to Ameliorate 6-Hydroxydopamine Toxicity and α-Synuclein Accumulation in Parkinson's Disease Models In Vivo and In Vitro. Int J Mol Sci 2021; 22:ijms221910240. [PMID: 34638579 PMCID: PMC8549710 DOI: 10.3390/ijms221910240] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 02/06/2023] Open
Abstract
Parkinson’s disease (PD) is a degenerative disease that can cause motor, cognitive, and behavioral disorders. The treatment strategies being developed are based on the typical pathologic features of PD, including the death of dopaminergic (DA) neurons in the substantia nigra of the midbrain and the accumulation of α-synuclein in neurons. Peiminine (PMN) is an extract of Fritillaria thunbergii Miq that has antioxidant and anti-neuroinflammatory effects. We used Caenorhabditis elegans and SH-SY5Y cell models of PD to evaluate the neuroprotective potential of PMN and address its corresponding mechanism of action. We found that pretreatment with PMN reduced reactive oxygen species production and DA neuron degeneration caused by exposure to 6-hydroxydopamine (6-OHDA), and therefore significantly improved the DA-mediated food-sensing behavior of 6-OHDA-exposed worms and prolonged their lifespan. PMN also diminished the accumulation of α-synuclein in transgenic worms and transfected cells. In our study of the mechanism of action, we found that PMN lessened ARTS-mediated degradation of X-linked inhibitor of apoptosis (XIAP) by enhancing the expression of PINK1/parkin. This led to reduced 6-OHDA-induced apoptosis, enhanced activity of the ubiquitin–proteasome system, and increased autophagy, which diminished the accumulation of α-synuclein. The use of small interfering RNA to down-regulate parkin reversed the benefits of PMN in the PD models. Our findings suggest PMN as a candidate compound worthy of further evaluation for the treatment of PD.
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Affiliation(s)
- Yu-Ling Hsu
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; (Y.-L.H.); (H.-S.H.); (S.-P.L.); (Y.-T.C.); (W.-C.S.)
| | - Huey-Shan Hung
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; (Y.-L.H.); (H.-S.H.); (S.-P.L.); (Y.-T.C.); (W.-C.S.)
- Translational Medicine Research Center, China Medical University Hospital, Taichung 40447, Taiwan
| | - Chia-Wen Tsai
- Department of Nutrition, China Medical University, Taichung 40402, Taiwan;
| | - Shih-Ping Liu
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; (Y.-L.H.); (H.-S.H.); (S.-P.L.); (Y.-T.C.); (W.-C.S.)
- Translational Medicine Research Center, China Medical University Hospital, Taichung 40447, Taiwan
| | - Yu-Ting Chiang
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; (Y.-L.H.); (H.-S.H.); (S.-P.L.); (Y.-T.C.); (W.-C.S.)
| | - Yun-Hua Kuo
- Department of Nursing, Taipei Veterans General Hospital, Taipei 12217, Taiwan;
| | - Woei-Cherng Shyu
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; (Y.-L.H.); (H.-S.H.); (S.-P.L.); (Y.-T.C.); (W.-C.S.)
- Translational Medicine Research Center, China Medical University Hospital, Taichung 40447, Taiwan
| | - Shinn-Zong Lin
- Bioinnovation Center, Tzu Chi Foundation, Department of Neurosurgery, Buddhist Tzu Chi General Hospital, Tzu Chi University, Hualien 970, Taiwan;
| | - Ru-Huei Fu
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; (Y.-L.H.); (H.-S.H.); (S.-P.L.); (Y.-T.C.); (W.-C.S.)
- Translational Medicine Research Center, China Medical University Hospital, Taichung 40447, Taiwan
- Department of Psychology, Asia University, Taichung 41354, Taiwan
- Correspondence: ; Tel.: +886-422052121-7826
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Hao Q, Chen J, Liao J, Huang Y, Gan Y, Larisch S, Zeng SX, Lu H, Zhou X. p53 induces ARTS to promote mitochondrial apoptosis. Cell Death Dis 2021; 12:204. [PMID: 33627621 PMCID: PMC7904775 DOI: 10.1038/s41419-021-03463-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 01/13/2021] [Accepted: 01/19/2021] [Indexed: 11/09/2022]
Abstract
Apoptosis related protein in TGF-β signaling pathway (ARTS) was originally discovered in cells undergoing apoptosis in response to TGF-β, but ARTS also acts downstream of many other apoptotic stimuli. ARTS induces apoptosis by antagonizing the anti-apoptotic proteins XIAP and Bcl-2. Here we identified the pro-apoptotic Sept4/ARTS gene as a p53-responsive target gene. Ectopic p53 and a variety of p53-inducing agents increased both mRNA and protein levels of ARTS, whereas ablation of p53 reduced ARTS expression in response to multiple stress conditions. Also, γ-irradiation induced p53-dependent ARTS expression in mice. Consistently, p53 binds to the responsive DNA element on the ARTS promoter and transcriptionally activated the promoter-driven expression of a luciferase reporter gene. Interestingly, ARTS binds to and sequesters p53 at mitochondria, enhancing the interaction of the latter with Bcl-XL. Ectopic ARTS markedly augments DNA damage stress- or Nutlin-3-triggered apoptosis, while ablation of ARTS preferentially impairs p53-induced apoptosis. Altogether, these findings demonstrate that ARTS collaborates with p53 in mitochondria-engaged apoptosis.
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Affiliation(s)
- Qian Hao
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Jiaxiang Chen
- Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA, 70112, USA
- Department of Physiology, Medical College of Nanchang University, Nanchang, 330006, China
| | - Junming Liao
- Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA, 70112, USA
| | - Yingdan Huang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Yu Gan
- Department of Physiology, Medical College of Nanchang University, Nanchang, 330006, China
| | - Sarit Larisch
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa, 31905, Israel
| | - Shelya X Zeng
- Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA, 70112, USA
| | - Hua Lu
- Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA, 70112, USA.
| | - Xiang Zhou
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032, China.
- Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Fudan University, Shanghai, 200032, China.
- Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
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IAP-Mediated Protein Ubiquitination in Regulating Cell Signaling. Cells 2020; 9:cells9051118. [PMID: 32365919 PMCID: PMC7290580 DOI: 10.3390/cells9051118] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 12/12/2022] Open
Abstract
Over the last decade, the E3-ubiquitine ligases from IAP (Inhibitor of Apoptosis) family have emerged as potent regulators of immune response. In immune cells, they control signaling pathways driving differentiation and inflammation in response to stimulation of tumor necrosis factor receptor (TNFR) family, pattern-recognition receptors (PRRs), and some cytokine receptors. They are able to control the activity, the cellular fate, or the stability of actors of signaling pathways, acting at different levels from components of receptor-associated multiprotein complexes to signaling effectors and transcription factors, as well as cytoskeleton regulators. Much less is known about ubiquitination substrates involved in non-immune signaling pathways. This review aimed to present IAP ubiquitination substrates and the role of IAP-mediated ubiquitination in regulating signaling pathways.
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Abbas R, Larisch S. Targeting XIAP for Promoting Cancer Cell Death-The Story of ARTS and SMAC. Cells 2020; 9:cells9030663. [PMID: 32182843 PMCID: PMC7140716 DOI: 10.3390/cells9030663] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 12/18/2022] Open
Abstract
Inhibitors of apoptosis (IAPs) are a family of proteins that regulate cell death and inflammation. XIAP (X-linked IAP) is the only family member that suppresses apoptosis by directly binding to and inhibiting caspases. On the other hand, cIAPs suppress the activation of the extrinsic apoptotic pathway by preventing the formation of pro-apoptotic signaling complexes. IAPs are negatively regulated by IAP-antagonist proteins such as Smac/Diablo and ARTS. ARTS can promote apoptosis by binding and degrading XIAP via the ubiquitin proteasome-system (UPS). Smac can induce the degradation of cIAPs but not XIAP. Many types of cancer overexpress IAPs, thus enabling tumor cells to evade apoptosis. Therefore, IAPs, and in particular XIAP, have become attractive targets for cancer therapy. In this review, we describe the differences in the mechanisms of action between Smac and ARTS, and we summarize efforts to develop cancer therapies based on mimicking Smac and ARTS. Several Smac-mimetic small molecules are currently under evaluation in clinical trials. Initial efforts to develop ARTS-mimetics resulted in a novel class of compounds, which bind and degrade XIAP but not cIAPs. Smac-mimetics can target tumors with high levels of cIAPs, whereas ARTS-mimetics are expected to be effective for cancers with high levels of XIAP.
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Edison N, Curtz Y, Paland N, Mamriev D, Chorubczyk N, Haviv-Reingewertz T, Kfir N, Morgenstern D, Kupervaser M, Kagan J, Kim HT, Larisch S. Degradation of Bcl-2 by XIAP and ARTS Promotes Apoptosis. Cell Rep 2018; 21:442-454. [PMID: 29020630 DOI: 10.1016/j.celrep.2017.09.052] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 12/17/2016] [Accepted: 09/15/2017] [Indexed: 01/21/2023] Open
Abstract
We describe a mechanism by which the anti-apoptotic B cell lymphoma 2 (Bcl-2) protein is downregulated to induce apoptosis. ARTS (Sept4_i2) is a tumor suppressor protein that promotes cell death through specifically antagonizing XIAP (X-linked inhibitor of apoptosis). ARTS and Bcl-2 reside at the outer mitochondrial membrane in living cells. Upon apoptotic induction, ARTS brings XIAP and Bcl-2 into a ternary complex, allowing XIAP to promote ubiquitylation and degradation of Bcl-2. ARTS binding to Bcl-2 involves the BH3 domain of Bcl-2. Lysine 17 in Bcl-2 serves as the main acceptor for ubiquitylation, and a Bcl-2 K17A mutant has increased stability and is more potent in protection against apoptosis. Bcl-2 ubiquitylation is reduced in both XIAP- and Sept4/ARTS-deficient MEFs, demonstrating that XIAP serves as an E3 ligase for Bcl-2 and that ARTS is essential for this process. Collectively, these results suggest a distinct model for the regulation of Bcl-2 by ARTS-mediated degradation.
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Affiliation(s)
- Natalia Edison
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel
| | - Yael Curtz
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel
| | - Nicole Paland
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel
| | - Dana Mamriev
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel
| | - Nicolas Chorubczyk
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel
| | - Tali Haviv-Reingewertz
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel
| | - Nir Kfir
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel
| | - David Morgenstern
- De Botton Institute for Protein Profiling, Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Meital Kupervaser
- De Botton Institute for Protein Profiling, Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Juliana Kagan
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel
| | - Hyoung Tae Kim
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Sarit Larisch
- Cell Death and Cancer Research Laboratory, Department of Biology, University of Haifa, Haifa 31905, Israel.
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Horowitz M, Elstein D, Zimran A, Goker-Alpan O. New Directions in Gaucher Disease. Hum Mutat 2016; 37:1121-1136. [DOI: 10.1002/humu.23056] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 07/20/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Mia Horowitz
- Department of Cell Research and Immunology, Faculty of Life Sciences; Tel Aviv University; Ramat Aviv Israel
| | - Deborah Elstein
- Gaucher Clinic; Shaare Zedek Medical Center; Jerusalem Israel
| | - Ari Zimran
- Gaucher Clinic; Shaare Zedek Medical Center; Jerusalem Israel
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Digital gene expression analysis of transcriptomes in lipopolysaccharide-induced acute respiratory distress syndrome. Clin Chim Acta 2015. [PMID: 26216187 DOI: 10.1016/j.cca.2015.07.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The mortality from acute respiratory distress syndrome (ARDS) is high, and its exact pathogenesis remains unclear, which forms a major obstacle for prevention and treatment of this disease. In the present study, we used digital gene expression (DGE) to detect the differentially expressed genes of the lung at 4h after lipopolysaccharide (LPS) exposure in a mouse model. METHODS Mice were treated with LPS or control saline by intratracheal instillation for 4h, and their lung tissues were collected for DGE analysis. We used a false discovery rate ≤0.001 and an absolute value of the log2 ratio≥1 as the thresholds for judging the significance of any difference in gene expression between the two members of each pair of mice. RESULTS We obtained 3,387,842 clean tags (i.e., after filtering to remove potentially erroneous tags) and about 84,513 corresponding distinct clean tags (i.e., types of tag). Approximately 91.20% of the clean tags could be mapped, and 82.71% could be uniquely mapped, to the reference tags, and 3.82% were unknown tags. At least 2200 differentially expressed genes were identified and analyzed for enrichment of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway. Twenty genes with the greatest difference in expression levels between the two members of every pair of mice were chosen. The majority of these genes are involved in signaling transduction, molecular adhesion, and metabolic pathways. CONCLUSIONS Using the powerful technology of DGE, we present, to our knowledge, the first in-depth transcriptomic analysis of mouse lungs after LPS exposure. We found some differentially expressed genes that might play important roles in the pathogenesis of ARDS.
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Bendikov-Bar I, Rapaport D, Larisch S, Horowitz M. Parkin-mediated ubiquitination of mutant glucocerebrosidase leads to competition with its substrates PARIS and ARTS. Orphanet J Rare Dis 2014; 9:86. [PMID: 24935484 PMCID: PMC4074407 DOI: 10.1186/1750-1172-9-86] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/28/2014] [Indexed: 01/07/2023] Open
Abstract
Background Parkinson’s disease (PD) is a movement neurodegenerative disorder characterized by death of dopaminergic neurons in the substantia nigra pars compacta of the brain that leads to movement impairments including bradykinesia, resting tremor, postural instability and rigidity. Mutations in several genes have been associated with familial PD, such as parkin, pink, DJ-1, LRKK2 and α-synuclein. Lately, mutations in the GBA gene were recognized as a major cause for the development of PD. Mutations in the GBA gene, which encodes for lysosomal β-glucocerebrosidase (GCase), lead to Gaucher disease (GD), an autosomal recessive sphingolipidosis characterized by accumulation of glucosylceramide, mainly in monocyte-derived cells. It is a heterogeneous disease, with Type 1 patients that do not present any primary neurological signs, and Type 2 or Type 3 patients who suffer from a neurological disease. The propensity of type 1 GD patients and carriers of GD mutations to develop PD is significantly higher than that of the non-GD population. We have shown in the past that parkin and mutant GCase, expressed in heterologous systems, interact with each other, and that normal but not mutant parkin mediates K48-dependent proteasomal degradation of mutant GCase variants. Methods We tested possible competition between mutant GCase and PARIS or ARTS on the E3 ubiquitin ligase parkin, using coimmunoprecipitation assays and quantitative real-time PCR. Results We show that endogenous mutant GCase variants associate with parkin and undergo parkin-dependent degradation. Mutant GCase competes with the known parkin substrates PARIS and ARTS, whose accumulation leads to apoptosis. Dopaminergic cells expressing mutant GCase are more susceptible to apoptotic stimuli than dopaminergic cells expressing normal GCase, present increased cleavage of caspase 3 and caspase 9 levels and undergo cell death. Conclusions Our results imply that presence of mutant GCase leads to accumulation of parkin substrates like PARIS and ARTS, which may cause apoptotic death of cells.
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Affiliation(s)
| | | | | | - Mia Horowitz
- Department of Cell Research and Immunology, Life Sciences, Tel Aviv University, Levanon St, Ramat Aviv 69978, Israel.
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Caspase-dependent regulation of the ubiquitin-proteasome system through direct substrate targeting. Proc Natl Acad Sci U S A 2013; 110:14284-9. [PMID: 23940367 DOI: 10.1073/pnas.1306179110] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Drosophila inhibitor of apoptosis (IAP) 1 (DIAP1) is an E3 ubiquitin ligase that regulates apoptosis in flies, in large part through direct inhibition and/or ubiquitinylation of caspases. IAP antagonists, such as Reaper, Hid, and Grim, are thought to induce cell death by displacing active caspases from baculovirus IAP repeat domains in DIAP1, but can themselves become targets of DIAP1-mediated ubiquitinylation. Herein, we demonstrate that Grim self-associates in cells and is ubiquitinylated by DIAP1 at Lys136 in an UbcD1-dependent manner, resulting in its rapid turnover. K48-linked ubiquitin chains are added almost exclusively to BIR2-bound Grim as a result of its structural proximity to DIAP1's RING domain. However, active caspases can simultaneously cleave Grim at Asp132, removing the lysine necessary for ubiquitinylation as well as any existing ubiquitin conjugates. Cleavage therefore enhances the stability of Grim and initiates a feed-forward caspase amplification loop, resulting in greater cell death. In summary, Grim is a caspase substrate whose cleavage promotes apoptosis by limiting, in a target-specific fashion, its ubiquitinylation and turnover by the proteasome.
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Kemeny S, Dery D, Loboda Y, Rovner M, Lev T, Zuri D, Finberg JPM, Larisch S. Parkin promotes degradation of the mitochondrial pro-apoptotic ARTS protein. PLoS One 2012; 7:e38837. [PMID: 22792159 PMCID: PMC3392246 DOI: 10.1371/journal.pone.0038837] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 05/11/2012] [Indexed: 01/11/2023] Open
Abstract
Parkinson's disease (PD) is associated with excessive cell death causing selective loss of dopaminergic neurons. Dysfunction of the Ubiquitin Proteasome System (UPS) is associated with the pathophysiology of PD. Mutations in Parkin which impair its E3-ligase activity play a major role in the pathogenesis of inherited PD. ARTS (Sept4_i2) is a mitochondrial protein, which initiates caspase activation upstream of cytochrome c release in the mitochondrial apoptotic pathway. Here we show that Parkin serves as an E3-ubiquitin ligase to restrict the levels of ARTS through UPS-mediated degradation. Though Parkin binds equally to ARTS and Sept4_i1 (H5/PNUTL2), the non-apoptotic splice variant of Sept4, Parkin ubiquitinates and degrades only ARTS. Thus, the effect of Parkin on ARTS is specific and probably related to its pro-apoptotic function. High levels of ARTS are sufficient to promote apoptosis in cultured neuronal cells, and rat brains treated with 6-OHDA reveal high levels of ARTS. However, over-expression of Parkin can protect cells from ARTS-induced apoptosis. Furthermore, Parkin loss-of-function experiments reveal that reduction of Parkin causes increased levels of ARTS and apoptosis. We propose that in brain cells in which the E3-ligase activity of Parkin is compromised, ARTS levels increase and facilitate apoptosis. Thus, ARTS is a novel substrate of Parkin. These observations link Parkin directly to a pro-apoptotic protein and reveal a novel connection between Parkin, apoptosis, and PD.
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Affiliation(s)
- Stav Kemeny
- Cell Death Research Laboratory, Department of Biology, Faculty of Sciences, University of Haifa, Mount Carmel, Haifa, Israel
- Department of Molecular Pharmacology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, Bat-Galim, Haifa, Israel
| | - Dikla Dery
- Cell Death Research Laboratory, Department of Biology, Faculty of Sciences, University of Haifa, Mount Carmel, Haifa, Israel
| | - Yelena Loboda
- Department of Molecular Pharmacology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, Bat-Galim, Haifa, Israel
| | - Marshall Rovner
- Cell Death Research Laboratory, Department of Biology, Faculty of Sciences, University of Haifa, Mount Carmel, Haifa, Israel
| | - Tali Lev
- Cell Death Research Laboratory, Department of Biology, Faculty of Sciences, University of Haifa, Mount Carmel, Haifa, Israel
| | - Dotan Zuri
- Cell Death Research Laboratory, Department of Biology, Faculty of Sciences, University of Haifa, Mount Carmel, Haifa, Israel
| | - John P. M. Finberg
- Department of Molecular Pharmacology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, Bat-Galim, Haifa, Israel
| | - Sarit Larisch
- Cell Death Research Laboratory, Department of Biology, Faculty of Sciences, University of Haifa, Mount Carmel, Haifa, Israel
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