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Mao L, Shaabani N, Zhang X, Jin C, Xu W, Argent C, Kushnareva Y, Powers C, Stegman K, Liu J, Xie H, Xu C, Bao Y, Xu L, Zhang Y, Yang H, Qian S, Hu Y, Shao J, Zhang C, Li T, Li Y, Liu N, Lin Z, Wang S, Wang C, Shen W, Lin Y, Shu D, Zhu Z, Kotoi O, Kerwin L, Han Q, Chumakova L, Teijaro J, Royal M, Brunswick M, Allen R, Ji H, Lu H, Xu X. Olgotrelvir, a dual inhibitor of SARS-CoV-2 M pro and cathepsin L, as a standalone antiviral oral intervention candidate for COVID-19. Med 2024; 5:169-171. [PMID: 38340710 DOI: 10.1016/j.medj.2024.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
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2
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Mao L, Shaabani N, Zhang X, Jin C, Xu W, Argent C, Kushnareva Y, Powers C, Stegman K, Liu J, Xie H, Xu C, Bao Y, Xu L, Zhang Y, Yang H, Qian S, Hu Y, Shao J, Zhang C, Li T, Li Y, Liu N, Lin Z, Wang S, Wang C, Shen W, Lin Y, Shu D, Zhu Z, Kotoi O, Kerwin L, Han Q, Chumakova L, Teijaro J, Royal M, Brunswick M, Allen R, Ji H, Lu H, Xu X. Olgotrelvir, a dual inhibitor of SARS-CoV-2 M pro and cathepsin L, as a standalone antiviral oral intervention candidate for COVID-19. Med 2024; 5:42-61.e23. [PMID: 38181791 DOI: 10.1016/j.medj.2023.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/18/2023] [Accepted: 12/03/2023] [Indexed: 01/07/2024]
Abstract
BACKGROUND Oral antiviral drugs with improved antiviral potency and safety are needed to address current challenges in clinical practice for treatment of COVID-19, including the risks of rebound, drug-drug interactions, and emerging resistance. METHODS Olgotrelvir (STI-1558) is designed as a next-generation antiviral targeting the SARS-CoV-2 main protease (Mpro), an essential enzyme for SARS-CoV-2 replication, and human cathepsin L (CTSL), a key enzyme for SARS-CoV-2 entry into host cells. FINDINGS Olgotrelvir is a highly bioavailable oral prodrug that is converted in plasma to its active form, AC1115. The dual mechanism of action of olgotrelvir and AC1115 was confirmed by enzyme activity inhibition assays and co-crystal structures of AC1115 with SARS-CoV-2 Mpro and human CTSL. AC1115 displayed antiviral activity by inhibiting replication of all tested SARS-CoV-2 variants in cell culture systems. Olgotrelvir also inhibited viral entry into cells using SARS-CoV-2 Spike-mediated pseudotypes by inhibition of host CTSL. In the K18-hACE2 transgenic mouse model of SARS-CoV-2-mediated disease, olgotrelvir significantly reduced the virus load in the lungs, prevented body weight loss, and reduced cytokine release and lung pathologies. Olgotrelvir demonstrated potent activity against the nirmatrelvir-resistant Mpro E166 mutants. Olgotrelvir showed enhanced oral bioavailability in animal models and in humans with significant plasma exposure without ritonavir. In phase I studies (ClinicalTrials.gov: NCT05364840 and NCT05523739), olgotrelvir demonstrated a favorable safety profile and antiviral activity. CONCLUSIONS Olgotrelvir is an oral inhibitor targeting Mpro and CTSL with high antiviral activity and plasma exposure and is a standalone treatment candidate for COVID-19. FUNDING Funded by Sorrento Therapeutics.
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Affiliation(s)
- Long Mao
- ACEA Therapeutics, Inc., San Diego, CA 92121, USA
| | | | - Xiaoying Zhang
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Can Jin
- ACEA Therapeutics, Inc., San Diego, CA 92121, USA
| | - Wanhong Xu
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | | | | | - Colin Powers
- Sorrento Therapeutics, Inc., San Diego, CA 92121, USA
| | - Karen Stegman
- Sorrento Therapeutics, Inc., San Diego, CA 92121, USA
| | - Jia Liu
- ACEA Therapeutics, Inc., San Diego, CA 92121, USA
| | - Hui Xie
- Sorrento Therapeutics, Inc., San Diego, CA 92121, USA
| | - Changxu Xu
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Yimei Bao
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Lijun Xu
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Yuren Zhang
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Haigang Yang
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Shengdian Qian
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Yong Hu
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Jianping Shao
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Can Zhang
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Tingting Li
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Yi Li
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Na Liu
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Zhenhao Lin
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Shanbo Wang
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Chao Wang
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Wei Shen
- ACEA Pharmaceutical Co., Ltd., Hangzhou, Zhejiang, P.R. China
| | - Yuanlong Lin
- Shenzhen Third People's Hospital, SUSTech, Shenzhen, P.R. China
| | - Dan Shu
- Shenzhen Third People's Hospital, SUSTech, Shenzhen, P.R. China
| | - Zhenhong Zhu
- ACEA Therapeutics, Inc., San Diego, CA 92121, USA
| | - Olivia Kotoi
- ACEA Therapeutics, Inc., San Diego, CA 92121, USA
| | - Lisa Kerwin
- Sorrento Therapeutics, Inc., San Diego, CA 92121, USA
| | - Qing Han
- Structure Based Design, Inc., San Diego, CA 92121, USA
| | | | - John Teijaro
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Mike Royal
- Sorrento Therapeutics, Inc., San Diego, CA 92121, USA
| | | | - Robert Allen
- Sorrento Therapeutics, Inc., San Diego, CA 92121, USA
| | - Henry Ji
- Sorrento Therapeutics, Inc., San Diego, CA 92121, USA
| | - Hongzhou Lu
- Shenzhen Third People's Hospital, SUSTech, Shenzhen, P.R. China.
| | - Xiao Xu
- ACEA Therapeutics, Inc., San Diego, CA 92121, USA.
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Kushnareva Y, Moraes V, Suess J, Peters B, Newmeyer DD, Kuwana T. Disruption of mitochondrial quality control genes promotes caspase-resistant cell survival following apoptotic stimuli. J Biol Chem 2022; 298:101835. [PMID: 35304098 PMCID: PMC9018395 DOI: 10.1016/j.jbc.2022.101835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 03/06/2022] [Accepted: 03/07/2022] [Indexed: 11/24/2022] Open
Abstract
In cells undergoing cell-intrinsic apoptosis, mitochondrial outer membrane permeabilization (MOMP) typically marks an irreversible step in the cell death process. However, in some cases, a subpopulation of treated cells can exhibit a sublethal response, termed "minority MOMP." In this phenomenon, the affected cells survive, despite a low level of caspase activation and subsequent limited activation of the endonuclease caspase-activated DNase (DNA fragmentation factor subunit beta). Consequently, these cells can experience DNA damage, increasing the probability of oncogenesis. However, little is known about the minority MOMP response. To discover genes that affect the MOMP response in individual cells, we conducted an imaging-based phenotypic siRNA screen. We identified multiple candidate genes whose downregulation increased the heterogeneity of MOMP within single cells, among which were genes related to mitochondrial dynamics and mitophagy that participate in the mitochondrial quality control (MQC) system. Furthermore, to test the hypothesis that functional MQC is important for reducing the frequency of minority MOMP, we developed an assay to measure the clonogenic survival of caspase-engaged cells. We found that cells deficient in various MQC genes were indeed prone to aberrant post-MOMP survival. Our data highlight the important role of proteins involved in mitochondrial dynamics and mitophagy in preventing apoptotic dysregulation and oncogenesis.
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Affiliation(s)
- Yulia Kushnareva
- Division of Immune Regulation, La Jolla Institute for Immunology, La Jolla, California, USA
| | - Vivian Moraes
- Division of Immune Regulation, La Jolla Institute for Immunology, La Jolla, California, USA
| | - Julian Suess
- Department of Biochemical Pharmacology, University of Konstanz, Konstanz, Germany
| | - Bjoern Peters
- Division of Immune Regulation, La Jolla Institute for Immunology, La Jolla, California, USA
| | - Donald D Newmeyer
- Division of Immune Regulation, La Jolla Institute for Immunology, La Jolla, California, USA
| | - Tomomi Kuwana
- Division of Immune Regulation, La Jolla Institute for Immunology, La Jolla, California, USA.
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4
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Kushnareva Y, Mathews IT, Andreyev AY, Altay G, Lindestam Arlehamn CS, Pandurangan V, Nilsson R, Jain M, Sette A, Peters B, Sharma S. Functional Analysis of Immune Signature Genes in Th1* Memory Cells Links ISOC1 and Pyrimidine Metabolism to IFN-γ and IL-17 Production. J Immunol 2021; 206:1181-1193. [PMID: 33547171 PMCID: PMC7946769 DOI: 10.4049/jimmunol.2000672] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 01/04/2021] [Indexed: 12/12/2022]
Abstract
CCR6+CXCR3+CCR4-CD4+ memory T cells, termed Th1*, are important for long-term immunity to Mycobacterium tuberculosis and the pathogenesis of autoimmune diseases. Th1* cells express a unique set of lineage-specific transcription factors characteristic of both Th1 and Th17 cells and display distinct gene expression profiles compared with other CD4+ T cell subsets. To examine molecules and signaling pathways important for the effector function of Th1* cells, we performed loss-of-function screening of genes selectively enriched in the Th1* subset. The genetic screen yielded candidates whose depletion significantly impaired TCR-induced IFN-γ production. These included genes previously linked to IFN-γ or M. tuberculosis susceptibility and novel candidates, such as ISOC1, encoding a metabolic enzyme of unknown function in mammalian cells. ISOC1-depleted T cells, which produced less IFN-γ and IL-17, displayed defects in oxidative phosphorylation and glycolysis and impairment of pyrimidine metabolic pathway. Supplementation with extracellular pyrimidines rescued both bioenergetics and IFN-γ production in ISOC1-deficient T cells, indicating that pyrimidine metabolism is a key driver of effector functions in CD4+ T cells and Th1* cells. Results provide new insights into the immune-stimulatory function of ISOC1 as well as the particular metabolic requirements of human memory T cells, providing a novel resource for understanding long-term T cell-driven responses.
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Affiliation(s)
| | - Ian T Mathews
- La Jolla Institute for Immunology, La Jolla, CA 92037
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Alexander Y Andreyev
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093
- The Scripps Research Institute, La Jolla, CA 92037; and
| | - Gokmen Altay
- La Jolla Institute for Immunology, La Jolla, CA 92037
| | | | | | | | - Mohit Jain
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Alessandro Sette
- La Jolla Institute for Immunology, La Jolla, CA 92037
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Bjoern Peters
- La Jolla Institute for Immunology, La Jolla, CA 92037
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Sonia Sharma
- La Jolla Institute for Immunology, La Jolla, CA 92037;
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Marin M, Kushnareva Y, Mason CS, Chanda SK, Melikyan GB. HIV-1 Fusion with CD4+ T cells Is Promoted by Proteins Involved in Endocytosis and Intracellular Membrane Trafficking. Viruses 2019; 11:v11020100. [PMID: 30691001 PMCID: PMC6409670 DOI: 10.3390/v11020100] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 01/23/2019] [Indexed: 01/23/2023] Open
Abstract
The HIV-1 entry pathway into permissive cells has been a subject of debate. Accumulating evidence, including our previous single virus tracking results, suggests that HIV-1 can enter different cell types via endocytosis and CD4/coreceptor-dependent fusion with endosomes. However, recent studies that employed indirect techniques to infer the sites of HIV-1 entry into CD4+ T cells have concluded that endocytosis does not contribute to infection. To assess whether HIV-1 enters these cells via endocytosis, we probed the role of intracellular trafficking in HIV-1 entry/fusion by a targeted shRNA screen in a CD4+ T cell line. We performed a screen utilizing a direct virus-cell fusion assay as readout and identified several host proteins involved in endosomal trafficking/maturation, including Rab5A and sorting nexins, as factors regulating HIV-1 fusion and infection. Knockdown of these proteins inhibited HIV-1 fusion irrespective of coreceptor tropism, without altering the CD4 or coreceptor expression, or compromising the virus’ ability to mediate fusion of two adjacent cells initiated by virus-plasma membrane fusion. Ectopic expression of Rab5A in non-permissive cells harboring Rab5A shRNAs partially restored the HIV-cell fusion. Together, these results implicate endocytic machinery in productive HIV-1 entry into CD4+ T cells.
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Affiliation(s)
- Mariana Marin
- Department of Pediatric, Division of Infectious Diseases, Emory University School of Medicine, 2015 Uppergate Drive, Atlanta, GA 30322, USA.
| | - Yulia Kushnareva
- Functional Genomics Center, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA.
| | - Caleb S Mason
- Department of Pediatric, Division of Infectious Diseases, Emory University School of Medicine, 2015 Uppergate Drive, Atlanta, GA 30322, USA.
| | - Sumit K Chanda
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
| | - Gregory B Melikyan
- Department of Pediatric, Division of Infectious Diseases, Emory University School of Medicine, 2015 Uppergate Drive, Atlanta, GA 30322, USA.
- Children's Healthcare of Atlanta, Atlanta, GA 30322, USA.
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Kushnareva Y, Seong Y, Andreyev AY, Kuwana T, Kiosses WB, Votruba M, Newmeyer DD. Mitochondrial dysfunction in an Opa1(Q285STOP) mouse model of dominant optic atrophy results from Opa1 haploinsufficiency. Cell Death Dis 2016; 7:e2309. [PMID: 27468686 PMCID: PMC4973340 DOI: 10.1038/cddis.2016.160] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 04/29/2016] [Accepted: 05/02/2016] [Indexed: 12/22/2022]
Abstract
Mutations in the opa1 (optic atrophy 1) gene lead to autosomal dominant optic atrophy (ADOA), a hereditary eye disease. This gene encodes the Opa1 protein, a mitochondrial dynamin-related GTPase required for mitochondrial fusion and the maintenance of normal crista structure. The majority of opa1 mutations encode truncated forms of the protein, lacking a complete GTPase domain. It is unclear whether the phenotype results from haploinsufficiency or rather a deleterious effect of truncated Opa1 protein. We studied a heterozygous Opa1 mutant mouse carrying a defective allele with a stop codon in the beginning of the GTPase domain at residue 285, a mutation that mimics human pathological mutations. Using an antibody raised against an N-terminal portion of Opa1, we found that the level of wild-type protein was decreased in the mutant mice, as predicted. However, no truncated Opa1 protein was expressed. In embryonic fibroblasts isolated from the mutant mice, this partial loss of Opa1 caused mitochondrial respiratory deficiency and a selective loss of respiratory Complex IV subunits. Furthermore, partial Opa1 deficiency resulted in a substantial resistance to endoplasmic reticulum stress-induced death. On the other hand, the enforced expression of truncated Opa1 protein in cells containing normal levels of wild-type protein did not cause mitochondrial defects. Moreover, cells expressing the truncated Opa1 protein showed reduced Bax activation in response to apoptotic stimuli. Taken together, our results exclude deleterious dominant-negative or gain-of-function mechanisms for this type of Opa1 mutation and affirm haploinsufficiency as the mechanism underlying mitochondrial dysfunction in ADOA.
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Affiliation(s)
- Y Kushnareva
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - Y Seong
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - A Y Andreyev
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093, USA
| | - T Kuwana
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - W B Kiosses
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - M Votruba
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4LU, UK.,Cardiff Eye Unit, University Hospital Wales, Cardiff CF14 4XW, UK
| | - D D Newmeyer
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
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7
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Renault TT, Floros KV, Elkholi R, Corrigan KA, Kushnareva Y, Wieder SY, Lindtner C, Serasinghe MN, Asciolla JJ, Buettner C, Newmeyer DD, Chipuk JE. Mitochondrial shape governs BAX-induced membrane permeabilization and apoptosis. Mol Cell 2014; 57:69-82. [PMID: 25482509 DOI: 10.1016/j.molcel.2014.10.028] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 08/20/2014] [Accepted: 10/31/2014] [Indexed: 12/24/2022]
Abstract
Proapoptotic BCL-2 proteins converge upon the outer mitochondrial membrane (OMM) to promote mitochondrial outer membrane permeabilization (MOMP) and apoptosis. Here we investigated the mechanistic relationship between mitochondrial shape and MOMP and provide evidence that BAX requires a distinct mitochondrial size to induce MOMP. We utilized the terminal unfolded protein response pathway to systematically define proapoptotic BCL-2 protein composition after stress and then directly interrogated their requirement for a productive mitochondrial size. Complementary biochemical, cellular, in vivo, and ex vivo studies reveal that Mfn1, a GTPase involved in mitochondrial fusion, establishes a mitochondrial size that is permissive for proapoptotic BCL-2 family function. Cells with hyperfragmented mitochondria, along with size-restricted OMM model systems, fail to support BAX-dependent membrane association and permeabilization due to an inability to stabilize BAXα9·membrane interactions. This work identifies a mechanistic contribution of mitochondrial size in dictating BAX activation, MOMP, and apoptosis.
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Affiliation(s)
- Thibaud T Renault
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Konstantinos V Floros
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Rana Elkholi
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Kelly-Ann Corrigan
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Yulia Kushnareva
- Division of Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - Shira Y Wieder
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Claudia Lindtner
- Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Madhavika N Serasinghe
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - James J Asciolla
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Christoph Buettner
- The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Donald D Newmeyer
- Division of Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - Jerry E Chipuk
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Department of Dermatology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA.
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Kushnareva Y, Andreyev A, Kuwana T, Newmeyer D. Bax Initiates the Assembly of a Multimeric Catalyst that Facilitates Pore Formation in Mitochondrial Outer Membranes. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Abstract
Mitochondrial bioenergetic function is a key to cell life and death. Cells need energy not only to support their vital functions but also to die gracefully. Execution of an apoptotic program includes energy-dependent steps, including kinase signaling, formation of the apoptosome, and effector caspase activation. Under conditions of bioenergetic collapse, cells are diverted toward necrotic demise. Mitochondrial outer membrane permeabilization (MOMP) is a decisive event in the execution of apoptosis. It is also causally linked to a decline in bioenergetic function via different mechanisms, not merely due to cytochrome c dispersion. MOMP-induced bioenergetic deficiency is usually irreversible and commits cells to die, even when caspases are inactive. Here, we discuss the mechanisms by which MOMP impacts bioenergetics in different cell death paradigms.
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Affiliation(s)
- Yulia Kushnareva
- La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
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10
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Lartigue L, Kushnareva Y, Seong Y, Lin H, Faustin B, Newmeyer DD. Caspase-independent mitochondrial cell death results from loss of respiration, not cytotoxic protein release. Mol Biol Cell 2009; 20:4871-84. [PMID: 19793916 PMCID: PMC2785731 DOI: 10.1091/mbc.e09-07-0649] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 09/17/2009] [Accepted: 09/23/2009] [Indexed: 01/29/2023] Open
Abstract
In apoptosis, mitochondrial outer membrane permeabilization (MOMP) triggers caspase-dependent death. However, cells undergo clonogenic death even if caspases are blocked. One proposed mechanism involved the release of cytotoxic proteins (e.g., AIF and endoG) from mitochondria. To initiate MOMP directly without side effects, we created a tamoxifen-switchable BimS fusion protein. Surprisingly, even after MOMP, caspase-inhibited cells replicated DNA and divided for approximately 48 h before undergoing proliferation arrest. AIF and endoG remained in mitochondria. However, cells gradually lost mitochondrial membrane potential and ATP content, and DNA synthesis slowed to a halt by 72 h. These defects resulted from a partial loss of respiratory function, occurring 4-8 h after MOMP, that was not merely due to dispersion of cytochrome c. In particular, Complex I activity was completely lost, and Complex IV activity was reduced by approximately 70%, whereas Complex II was unaffected. Later, cells exhibited a more profound loss of mitochondrial protein constituents. Thus, under caspase inhibition, MOMP-induced clonogenic death results from a progressive loss of mitochondrial function, rather than the release of cytotoxic proteins from mitochondria.
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Affiliation(s)
- Lydia Lartigue
- *La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037; and
| | - Yulia Kushnareva
- *La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037; and
| | - Youngmo Seong
- *La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037; and
| | - Helen Lin
- *La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037; and
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Liot G, Bossy B, Lubitz S, Kushnareva Y, Sejbuk N, Bossy-Wetzel E. Complex II inhibition by 3-NP causes mitochondrial fragmentation and neuronal cell death via an NMDA- and ROS-dependent pathway. Cell Death Differ 2009; 16:899-909. [PMID: 19300456 DOI: 10.1038/cdd.2009.22] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Mitochondrial respiratory complex II inhibition plays a central role in Huntington's disease (HD). Remarkably, 3-NP, a complex II inhibitor, recapitulates HD-like symptoms. Furthermore, decreases in mitochondrial fusion or increases in mitochondrial fission have been implicated in neurodegenerative diseases. However, the relationship between mitochondrial energy defects and mitochondrial dynamics has never been explored in detail. In addition, the mechanism of neuronal cell death by complex II inhibition remains unclear. Here, we tested the temporal and spatial relationship between energy decline, impairment of mitochondrial dynamics, and neuronal cell death in response to 3-NP using quantitative fluorescence time-lapse microscopy and cortical neurons. 3-NP caused an immediate drop in ATP. This event corresponded with a mild rise in reactive oxygen species (ROS), but mitochondrial morphology remained unaltered. Unexpectedly, several hours after this initial phase, a second dramatic rise in ROS occurred, associated with profound mitochondrial fission characterized by the conversion of filamentous to punctate mitochondria and neuronal cell death. Glutamate receptor antagonist AP5 abolishes the second peak in ROS, mitochondrial fission, and cell death. Thus, secondary excitotoxicity, mediated by glutamate receptor activation of the NMDA subtype, and consequent oxidative and nitrosative stress cause mitochondrial fission, rather than energy deficits per se. These results improve our understanding of the cellular mechanisms underlying HD pathogenesis.
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Affiliation(s)
- G Liot
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA 92037, USA
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12
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Yamaguchi R, Lartigue L, Perkins G, Scott RT, Dixit A, Kushnareva Y, Kuwana T, Ellisman MH, Newmeyer DD. Opa1-mediated cristae opening is Bax/Bak and BH3 dependent, required for apoptosis, and independent of Bak oligomerization. Mol Cell 2008; 31:557-569. [PMID: 18691924 DOI: 10.1016/j.molcel.2008.07.010] [Citation(s) in RCA: 219] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2007] [Revised: 04/04/2008] [Accepted: 07/17/2008] [Indexed: 11/28/2022]
Abstract
Controversy surrounds the role and mechanism of mitochondrial cristae remodeling in apoptosis. Here we show that the proapoptotic BH3-only proteins Bid and Bim induced full cytochrome c release but only a subtle alteration of crista junctions, which involved the disassembly of Opa1 complexes. Both mitochondrial outer membrane permeabilization (MOMP) and crista junction opening (CJO) were caspase independent and required a functional BH3 domain and Bax/Bak. However, MOMP and CJO were experimentally separable. Pharmacological blockade of MOMP did not prevent Opa1 disassembly and CJO; moreover, expression of a disassembly-resistant mutant Opa1 (Q297V) blocked cytochrome c release and apoptosis but not Bax activation. Thus, apoptosis requires a subtle form of Opa1-dependent crista remodeling that is induced by BH3-only proteins and Bax/Bak but independent of MOMP.
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Affiliation(s)
- Ryuji Yamaguchi
- La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - Lydia Lartigue
- La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - Guy Perkins
- Department of Neurosciences and National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ray T Scott
- Department of Neurosciences and National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA 92093, USA
| | - Amruta Dixit
- Department of Neurosciences and National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yulia Kushnareva
- La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - Tomomi Kuwana
- Department of Pathology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Mark H Ellisman
- Department of Neurosciences and National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA 92093, USA
| | - Donald D Newmeyer
- La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA.
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13
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Barsoum MJ, Yuan H, Gerencser AA, Liot G, Kushnareva Y, Gräber S, Kovacs I, Lee WD, Waggoner J, Cui J, White AD, Bossy B, Martinou JC, Youle RJ, Lipton SA, Ellisman MH, Perkins GA, Bossy-Wetzel E. Nitric oxide-induced mitochondrial fission is regulated by dynamin-related GTPases in neurons. EMBO J 2006; 25:3900-11. [PMID: 16874299 PMCID: PMC1553198 DOI: 10.1038/sj.emboj.7601253] [Citation(s) in RCA: 520] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 06/22/2006] [Indexed: 12/19/2022] Open
Abstract
Mitochondria are present as tubular organelles in neuronal projections. Here, we report that mitochondria undergo profound fission in response to nitric oxide (NO) in cortical neurons of primary cultures. Mitochondrial fission by NO occurs long before neurite injury and neuronal cell death. Furthermore, fission is accompanied by ultrastructural damage of mitochondria, autophagy, ATP decline and generation of free radicals. Fission is occasionally asymmetric and can be reversible. Strikingly, mitochondrial fission is also an early event in ischemic stroke in vivo. Mitofusin 1 (Mfn1) or dominant-negative Dynamin related protein 1 (Drp1(K38A)) inhibits mitochondrial fission induced by NO, rotenone and Amyloid-beta peptide. Conversely, overexpression of Drp1 or Fis1 elicits fission and increases neuronal loss. Importantly, NO-induced neuronal cell death was mitigated by Mfn1 and Drp1(K38A). Thus, persistent mitochondrial fission may play a causal role in NO-mediated neurotoxicity.
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Affiliation(s)
- Mark J Barsoum
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Hua Yuan
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Akos A Gerencser
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
| | - Géraldine Liot
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Yulia Kushnareva
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Simone Gräber
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Imre Kovacs
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Wilson D Lee
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Jenna Waggoner
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Jiankun Cui
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Andrew D White
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Blaise Bossy
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | | | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Stuart A Lipton
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Guy A Perkins
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Ella Bossy-Wetzel
- Apoptosis and Cell Death Program, Burnham Institute for Medical Research, La Jolla, CA, USA
- Degenerative Disease Program, Burnham Institute for Medical Research, USA
- Apoptosis & Cell Death Program, The Burnham Institute for Medical Research, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA. Tel.: +1 858 713 6297; Fax: +1 858 646 3195; E-mail:
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14
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Ward MW, Kushnareva Y, Greenwood S, Connolly CN. Cellular and subcellular calcium accumulation during glutamate-induced injury in cerebellar granule neurons. J Neurochem 2005; 92:1081-90. [PMID: 15715659 DOI: 10.1111/j.1471-4159.2004.02928.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Abstract We have investigated the role of Ca2+ accumulation and neuronal injury in cerebellar granule neurons after glutamate receptor overactivation. After the removal of the free cytosolic Ca2+ we identified an extensive second Ca2+ fraction (SCF) that is retained within the neurons after glutamate receptor overactivation. The SCF reaches a plateau within 10 min with the magnitude of this SCF accumulation reflecting the extent of the neuronal injury that occurs within the neurons. The existence of this SCF is sensitive to both NMDA receptor antagonists and mitochondrial inhibitors but is unaffected by agents that deplete endoplasmic reticulum Ca2+, indicating that this Ca2+ fraction may be located within the mitochondria. Through the isolation of mitochondria from cerebellar granule neurons treated with glutamate we have shown that the majority of the SCF is mitochondrial in location. On the removal of the glutamate stimulus the SCF recovers at a slower rate than the free Ca2+ concentration within the neuron. This is intriguing, as it implies a capacity to remember previous excitatory events. Most significantly we have shown that a short pre-application of subthreshold glutamate or kainate blocks both SCF Ca2+ accumulation and extensive neuronal injury in response to high concentrations of glutamate. These findings may be relevant to the observations of pre-conditioning in the brain and heart.
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Affiliation(s)
- Manus W Ward
- Department of Physiology, Royal College of Surgeons in Ireland, Dublin, Ireland.
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15
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Lee B, Miles PD, Vargas L, Luan P, Glasco S, Kushnareva Y, Kornbrust ES, Grako KA, Wollheim CB, Maechler P, Olefsky JM, Anderson CM. Inhibition of mitochondrial Na+-Ca2+ exchanger increases mitochondrial metabolism and potentiates glucose-stimulated insulin secretion in rat pancreatic islets. Diabetes 2003; 52:965-73. [PMID: 12663468 DOI: 10.2337/diabetes.52.4.965] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The mitochondrial Na(+)-Ca(2+) exchanger (mNCE) mediates efflux of Ca(2+) from mitochondria in exchange for influx of Na(+). We show that inhibition of the mNCE enhances mitochondrial oxidative metabolism and increases glucose-stimulated insulin secretion in rat islets and INS-1 cells. The benzothiazepine CGP37157 inhibited mNCE activity in INS-1 cells (50% inhibition at IC(50) = 1.5 micro mol/l) and increased the glucose-induced rise in mitochondrial Ca(2+) ([Ca(2+)](m)) 2.1 times. Cellular ATP content was increased by 13% in INS-1 cells and by 49% in rat islets by CGP37157 (1 micro mol/l). Krebs cycle flux was also stimulated by CGP37157 when glucose was present. Insulin secretion was increased in a glucose-dependent manner by CGP37157 in both INS-1 cells and islets. In islets, CGP37157 increased insulin secretion dose dependently (half-maximal efficacy at EC(50) = 0.06 micro mol/l) at 8 mmol/l glucose and shifted the glucose dose response curve to the left. In perifused islets, mNCE inhibition had no effect on insulin secretion at 2.8 mmol/l glucose but increased insulin secretion by 46% at 11 mmol/l glucose. The effects of CGP37157 could not be attributed to interactions with the plasma membrane sodium calcium exchanger, L-type calcium channels, ATP-sensitive K(+) channels, or [Ca(2+)](m) uniporter. In hyperglycemic clamp studies of Wistar rats, CGP37157 increased plasma insulin and C-peptide levels only during the hyperglycemic phase of the study. These results illustrate the potential utility of agents that affect mitochondrial metabolism as novel insulin secretagogues.
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Affiliation(s)
- Bumsup Lee
- Division of Metabolic Diseases, MitoKor, San Diego, California 92121, USA
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16
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Kushnareva Y, Murphy AN, Andreyev A. Complex I-mediated reactive oxygen species generation: modulation by cytochrome c and NAD(P)+ oxidation-reduction state. Biochem J 2002; 368:545-53. [PMID: 12180906 PMCID: PMC1222999 DOI: 10.1042/bj20021121] [Citation(s) in RCA: 501] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2002] [Accepted: 08/15/2002] [Indexed: 02/07/2023]
Abstract
Several lines of evidence indicate that mitochondrial reactive oxygen species (ROS) generation is the major source of oxidative stress in the cell. It has been shown that ROS production accompanies cytochrome c release in different apoptotic paradigms, but the site(s) of ROS production remain obscure. In the current study, we demonstrate that loss of cytochrome c by mitochondria oxidizing NAD(+)-linked substrates results in a dramatic increase of ROS production and respiratory inhibition. This increased ROS production can be mimicked by rotenone, a complex I inhibitor, as well as other chemical inhibitors of electron flow that act further downstream in the electron transport chain. The effects of cytochrome c depletion from mitoplasts on ROS production and respiration are reversible upon addition of exogenous cytochrome c. Thus in these models of mitochondrial injury, a primary site of ROS generation in both brain and heart mitochondria is proximal to the rotenone inhibitory site, rather than in complex III. ROS production at complex I is critically dependent upon a highly reduced state of the mitochondrial NAD(P)(+) pool and is achieved upon nearly complete inhibition of the respiratory chain. Redox clamp experiments using the acetoacetate/L-beta-hydroxybutyrate couple in the presence of a maximally inhibitory rotenone concentration suggest that the site is approx. 50 mV more electronegative than the NADH/NAD(+) couple. In the absence of inhibitors, this highly reduced state of mitochondria can be induced by reverse electron flow from succinate to NAD(+), accounting for profound ROS production in the presence of succinate. These results lead us to propose a model of thermodynamic control of mitochondrial ROS production which suggests that the ROS-generating site of complex I is the Fe-S centre N-1a.
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Affiliation(s)
- Yulia Kushnareva
- Mitochondrial Biology, MitoKor, 11494 Sorrento Valley Road, San Diego, CA 92024, U.S.A
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17
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Gudz T, Eriksson O, Kushnareva Y, Saris NE, Novgorodov S. Effect of butylhydroxytoluene and related compounds on permeability of the inner mitochondrial membrane. Arch Biochem Biophys 1997; 342:143-56. [PMID: 9185623 DOI: 10.1006/abbi.1997.0113] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mitochondrial inner membrane contains a latent pore (PTP) that when opened uncouples mitochondrial energy transduction and allows rapid equilibration of low-molecular-weight solutes between the matrix and exterior. Based on sensitivity of the PTP to well-known free radical scavenger butylhydroxytoluene (BHT), it has been proposed that increased steady-state level of oxygen radicals, and subsequent radical attack of proteins and lipids, is a central event in activation of this pore (Novgorodov et al., J. Bioenerg. Biomembr. 19, 191-202, 1987; Carbonera and Azzone, Biochim. Biophys. Acta 943, 245-255, 1988). Present studies revealed that DBT, a derivative of BHT devoid of radical scavenging activity, exerts an analogous effect on the permeability of the inner membrane. Inhibition of the Ca2+-induced PTP opening is essentially complete at dose range of 50-60 nmol/mg protein with IC50 values of about 32 and 23 nmol/mg protein for DBT and BHT, respectively. Electron microscopy and osmotic experiments utilizing polyethylene glycols with different Stokes radii showed that the apparent lack of inhibition seen at high concentrations of these compounds results from cyclosporin A- and Ca2+-insensitive pore formation in the inner membrane. Experiments employing antioxidants with similar structure but dissimilar hydrophobicity provided evidence for localization of the antioxidant binding sites within the hydrophobic zone of the inner membrane or in the matrix space. The data obtained do not refute the notion that oxygen radicals modulate the PTP, but rather indicate that BHT operates independently of its free radical scavenging activity. Overall, the sensitivity to BHT and other antioxidants is not always a reliable criterion for the involvement of free radical reactions in the processes under study.
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Affiliation(s)
- T Gudz
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russian Federation
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