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Qin M, Xie Z, Cao T, Wang Z, Zhang X, Wang F, Wei W, Jin M, Ma J, Zeng L, Wang Y, Pei S, Zhang X. Autophagy in Rat Müller Glial Cells Is Modulated by the Sirtuin 4/AMPK/mTOR Pathway and Induces Apoptosis under Oxidative Stress. Cells 2022; 11:cells11172645. [PMID: 36078054 PMCID: PMC9454555 DOI: 10.3390/cells11172645] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 08/14/2022] [Accepted: 08/18/2022] [Indexed: 11/30/2022] Open
Abstract
Müller glial cells (MGCs) are a group of glial cells in the retina that provide essential support to retinal neurons; however, the understanding of MGC apoptosis and autophagy remains limited. This study was aimed at investigating the role of autophagy in MGCs under normal and oxidative conditions, and identifying the underlying mechanisms. In addition, the sirtuin 4 (SIRT4)-mediated signaling pathway was observed to regulate the autophagic process in MGCs. To assess the effect of autophagy on MGC mitochondrial function and survival, we treated rMC-1 cells—rat-derived Müller glial cells—with rapamycin and 3-methyladenine (3-MA), and found that MGC death was not induced by such treatment, while autophagic dysfunction could increase MGC apoptosis under oxidative stress, as reflected by the expression level of cleaved caspase 3 and PI staining. In addition, the downregulation of autophagy by 3-MA could influence the morphology of the mitochondrial network structure, the mitochondrial membrane potential, and generation of reactive oxygen species (ROS) under oxidative stress. Moreover, SIRT4 depletion enhanced autophagosome formation, as verified by an increase in the LC3 II/I ratio and a decrease in the expression of SQSTM1/p62, and vice versa. The inhibition of AMPK phosphorylation by compound C could reverse these changes in LC3 II/I and SQSTM1/p62 caused by SIRT4 knockdown. Our research concludes that MGCs can endure autophagic dysfunction in the absence of oxidative stress, while the downregulation of autophagy can cause MGCs to become more sensitized to oxidative stress. Simultaneous exposure to oxidative stress and autophagic dysfunction in MGCs can result in a pronounced impairment of cell survival. Mechanically, SIRT4 depletion can activate the autophagic process in MGCs by regulating the AMPK–mTOR signaling pathway.
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Affiliation(s)
- Mengqi Qin
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Zhi Xie
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Ting Cao
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Zhiruo Wang
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Xiaoyu Zhang
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Feifei Wang
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Wei Wei
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Ming Jin
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Jingyuan Ma
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
- Queen Mary School, Nanchang University, Nanchang 330006, China
| | - Ling Zeng
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Yanan Wang
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Shaonan Pei
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
| | - Xu Zhang
- Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang 330006, China
- Correspondence:
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Kato T, Yokomori A, Suzuki R, Azegami J, El Enshasy HA, Park EY. Effects of a proteasome inhibitor on the riboflavin production in Ashbya gossypii. J Appl Microbiol 2021; 132:1176-1184. [PMID: 34496097 DOI: 10.1111/jam.15296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 09/01/2021] [Accepted: 09/01/2021] [Indexed: 10/20/2022]
Abstract
AIMS Effects of a proteasome inhibitor, MG-132, on the riboflavin production in Ashbya gossypii were investigated to elucidate the relationship of the riboflavin production with flavoprotein homeostasis. METHODS AND RESULTS The addition of MG-132 to the liquid medium reduced the specific riboflavin production by 79% in A. gossypii at 25 μM after 24 h. The addition of the inhibitor also caused the accumulation of reactive oxygen species and ubiquitinated proteins. These results indicated that MG-132 works in A. gossypii without any genetic engineering and reduces riboflavin production. In the presence of 25 μM MG-132, specific NADH dehydrogenase activity was increased by 1.4-fold compared to DMSO, but specific succinate dehydrogenase (SDH) activity was decreased to 52% compared to DMSO. Additionally, the amount of AgSdh1p (ACR052Wp) was also reduced. Specific riboflavin production was reduced to 22% when 20 mM malonate, a SDH inhibitor, was added to the culture medium. The riboflavin production in heterozygous AgSDH1 gene-disrupted mutant (AgSDH1-/+ ) was reduced to 63% compared to that in wild type. CONCLUSIONS MG-132 suppresses the riboflavin production and SDH activity in A. gossypii. SDH is one of the flavoproteins involved in the riboflavin production in A. gossypii. SIGNIFICANCE AND IMPACT OF THE STUDY This study shows that MG-132 has a negative influence on the riboflavin production and SDH activity in A. gossypii and leads to the elucidation of the connection of the riboflavin production with flavoproteins.
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Affiliation(s)
- Tatsuya Kato
- Green Chemistry Research Division, Research Institute of Green Science and Technology, Shizuoka University, Shizuoka, Japan.,Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan.,Department of Applied Life Science, Faculty of Agriculture, Shizuoka University, Shizuoka, Japan
| | - Ami Yokomori
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan
| | - Riho Suzuki
- Department of Applied Life Science, Faculty of Agriculture, Shizuoka University, Shizuoka, Japan
| | - Junya Azegami
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan
| | - Hesham A El Enshasy
- Institute of Bioproduct Development (IBD), Universiti Teknologi Malaysia (UTM), Johor Bahru, Malaysia.,City of Scientific Research and Technology Applications, New Borg Al Arab, Alexandria, Egypt
| | - Enoch Y Park
- Green Chemistry Research Division, Research Institute of Green Science and Technology, Shizuoka University, Shizuoka, Japan.,Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan.,Department of Applied Life Science, Faculty of Agriculture, Shizuoka University, Shizuoka, Japan
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Edskes HK, Stroobant EE, DeWilde MP, Bezsonov EE, Wickner RB. Proteasome Control of [URE3] Prion Propagation by Degradation of Anti-Prion Proteins Cur1 and Btn2 in Saccharomyces cerevisiae. Genetics 2021; 218:6179111. [PMID: 33742650 DOI: 10.1093/genetics/iyab037] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 02/27/2021] [Indexed: 01/16/2023] Open
Abstract
[URE3] is a prion of the nitrogen catabolism controller, Ure2p, and [PSI+] is a prion of the translation termination factor Sup35p in S. cerevisiae. Btn2p cures [URE3] by sequestration of Ure2p amyloid filaments. Cur1p, paralogous to Btn2p, also cures [URE3], but by a different (unknown) mechanism. We find that an array of mutations impairing proteasome assembly or MG132 inhibition of proteasome activity result in loss of [URE3]. In proportion to their prion-curing effects, each mutation affecting proteasomes elevates the cellular concentration of the anti-prion proteins Btn2 and Cur1. Of >4,600 proteins detected by SILAC, Btn2p was easily the most overexpressed in a pre9Δ (α3 core subunit) strain. Indeed, deletion of BTN2 and CUR1 prevents the prion-curing effects of proteasome impairment. Surprisingly, the 15 most unstable yeast proteins are not increased in pre9Δ cells suggesting altered proteasome specificity rather than simple inactivation. Hsp42, a chaperone that cooperates with Btn2 and Cur1 in curing [URE3], is also necessary for the curing produced by proteasome defects, although Hsp42p levels are not substantially altered by a proteasome defect. We find that pre9Δ and proteasome chaperone mutants that most efficiently lose [URE3], do not destabilize [PSI+] or alter cellular levels of Sup35p. A tof2 mutation or deletion likewise destabilizes [URE3], and elevates Btn2p, suggesting that Tof2p deficiency inactivates proteasomes. We suggest that when proteasomes are saturated with denatured/misfolded proteins, their reduced degradation of Btn2p and Cur1p automatically upregulates these aggregate-handling systems to assist in the clean-up.
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Affiliation(s)
- Herman K Edskes
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA
| | - Emily E Stroobant
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA
| | - Morgan P DeWilde
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA
| | - Evgeny E Bezsonov
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA
| | - Reed B Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA
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Zöller E, Laborenz J, Krämer L, Boos F, Räschle M, Alexander RT, Herrmann JM. The intermembrane space protein Mix23 is a novel stress-induced mitochondrial import factor. J Biol Chem 2020; 295:14686-14697. [PMID: 32826315 PMCID: PMC7586232 DOI: 10.1074/jbc.ra120.014247] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/19/2020] [Indexed: 12/20/2022] Open
Abstract
The biogenesis of mitochondria requires the import of hundreds of precursor proteins. These proteins are transported post-translationally with the help of chaperones, meaning that the overproduction of mitochondrial proteins or the limited availability of chaperones can lead to the accumulation of cytosolic precursor proteins. This imposes a severe challenge to cytosolic proteostasis and triggers a specific transcription program called the mitoprotein-induced stress response, which activates the proteasome system. This coincides with the repression of mitochondrial proteins, including many proteins of the intermembrane space. In contrast, herein we report that the so-far-uncharacterized intermembrane space protein Mix23 is considerably up-regulated when mitochondrial import is perturbed. Mix23 is evolutionarily conserved and a homolog of the human protein CCDC58. We found that, like the subunits of the proteasome, Mix23 is under control of the transcription factor Rpn4. It is imported into mitochondria by the mitochondrial disulfide relay. Mix23 is critical for the efficient import of proteins into the mitochondrial matrix, particularly if the function of the translocase of the inner membrane 23 is compromised such as in temperature-sensitive mutants of Tim17. Our observations identify Mix23 as a novel regulator or stabilizer of the mitochondrial protein import machinery that is specifically up-regulated upon mitoprotein-induced stress conditions.
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Affiliation(s)
- Eva Zöller
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Janina Laborenz
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Lena Krämer
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Felix Boos
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Markus Räschle
- Department of Molecular Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - R Todd Alexander
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Johannes M Herrmann
- Department of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany.
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The ubiquitin-proteasome system and its crosstalk with mitochondria as therapeutic targets in medicine. Pharmacol Res 2020; 163:105248. [PMID: 33065283 DOI: 10.1016/j.phrs.2020.105248] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 12/12/2022]
Abstract
The ubiquitin-proteasome system constitutes a major pathway for protein degradation in the cell. Therefore the crosstalk of this pathway with mitochondria is a major topic with direct relevance to many mitochondrial diseases. Proteasome dysfunction triggers not only protein toxicity, but also mitochondrial dysfunction. The involvement of proteasomes in the regulation of protein transport into mitochondria contributes to an increase in mitochondrial function defects. On the other hand, mitochondrial impairment stimulates reactive oxygen species production, which increases protein damage, and protein misfolding and aggregation leading to proteasome overload. Concurrently, mitochondrial dysfunction compromises cellular ATP production leading to reduced protein ubiquitination and proteasome activity. In this review we discuss the complex relationship and interdependence of the ubiquitin-proteasome system and mitochondria. Furthermore, we describe pharmacological inhibition of proteasome activity as a novel strategy to treat a group of mitochondrial diseases.
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Beyond Deubiquitylation: USP30-Mediated Regulation of Mitochondrial Homeostasis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1038:133-148. [DOI: 10.1007/978-981-10-6674-0_10] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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