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Bugga P, Stoner MW, Manning JR, Mushala BAS, Bhattarai N, Sharifi-Sanjani M, Webster BR, Thapa D, Scott I. Validation of GCN5L1/BLOC1S1/BLOS1 antibodies using knockout cells and tissue. Biochem J 2024; 481:643-651. [PMID: 38683688 DOI: 10.1042/bcj20230302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 04/18/2024] [Accepted: 04/29/2024] [Indexed: 05/02/2024]
Abstract
GCN5L1, also known as BLOC1S1 and BLOS1, is a small intracellular protein involved in many key biological processes. Over the last decade, GCN5L1 has been implicated in the regulation of protein lysine acetylation, energy metabolism, endo-lysosomal function, and cellular immune pathways. An increasing number of published papers have used commercially-available reagents to interrogate GCN5L1 function. However, in many cases these reagents have not been rigorously validated, leading to potentially misleading results. In this report we tested several commercially-available antibodies for GCN5L1, and found that two-thirds of those available did not unambiguously detect the protein by western blot in cultured mouse cells or ex vivo liver tissue. These data suggest that previously published studies which used these unverified antibodies to measure GCN5L1 protein abundance, in the absence of other independent methods of corroboration, should be interpreted with appropriate caution.
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Affiliation(s)
- Paramesha Bugga
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Michael W Stoner
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Janet R Manning
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Bellina A S Mushala
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Nisha Bhattarai
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Maryam Sharifi-Sanjani
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
| | - Bradley R Webster
- Department of Urology, Roswell Park Cancer Center, Buffalo, NY 14263, U.S.A
| | - Dharendra Thapa
- Department of Human Performance - Exercise Physiology, West Virginia University, Morgantown, WV 26506, U.S.A
| | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A
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Bugga P, Stoner MW, Manning JR, Mushala BA, Thapa D, Scott I. Validation of GCN5L1/BLOC1S1/BLOS1 Antibodies Using Knockout Cells and Tissue. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.21.550091. [PMID: 37503156 PMCID: PMC10370191 DOI: 10.1101/2023.07.21.550091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
GCN5L1, also known as BLOC1S1 and BLOS1, is a small intracellular protein involved in a number of key biological processes. Over the last decade, GCN5L1 has been implicated in the regulation of protein lysine acetylation, energy metabolism, endo-lysosomal function, and cellular immune pathways. An increasing number of published papers have used commercially-available reagents to interrogate GCN5L1 function. However, in many cases these reagents have not been rigorously validated, leading to potentially misleading results. In this report we tested several commercially-available antibodies for GCN5L1, and found that two-thirds of those available did not unambiguously detect the protein by western blot in cultured mouse cells or ex vivo liver tissue. These data suggest that previously published studies which used these unverified antibodies to measure GCN5L1 protein abundance, in the absence of other independent methods of corroboration, should be interpreted with appropriate caution.
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Affiliation(s)
- Paramesha Bugga
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Michael W. Stoner
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Janet R. Manning
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Bellina A.S. Mushala
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Dharendra Thapa
- Department of Human Performance - Exercise Physiology, West Virginia University, Morgantown, WV 26506
| | - Iain Scott
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
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Abstract
The global prevalences of obesity and type 2 diabetes mellitus have reached epidemic status, presenting a heavy burden on society. It is therefore essential to find novel mechanisms and targets that could be utilized in potential treatment strategies and, as such, intracellular membrane trafficking has re-emerged as a regulatory tool for controlling metabolic homeostasis. Membrane trafficking is an essential physiological process that is responsible for the sorting and distribution of signalling receptors, membrane transporters and hormones or other ligands between different intracellular compartments and the plasma membrane. Dysregulation of intracellular transport is associated with many human diseases, including cancer, neurodegeneration, immune deficiencies and metabolic diseases, such as type 2 diabetes mellitus and its associated complications. This Review focuses on the latest advances on the role of endosomal membrane trafficking in metabolic physiology and pathology in vivo, highlighting the importance of this research field in targeting metabolic diseases.
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Affiliation(s)
- Jerome Gilleron
- Université Côte d'Azur, Institut National de la Santé et de la Recherche Médicale (Inserm), UMR1065 C3M, Team Cellular and Molecular Pathophysiology of Obesity, Nice, France.
| | - Anja Zeigerer
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany.
- German Center for Diabetes Research (DZD), Neuherberg, Germany.
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Bae D, Jones RE, Piscopo KM, Tyagi M, Shepherd JD, Hollien J. Regulation of Blos1 by IRE1 prevents the accumulation of Huntingtin protein aggregates. Mol Biol Cell 2022; 33:ar125. [PMID: 36044348 PMCID: PMC9634971 DOI: 10.1091/mbc.e22-07-0281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Huntington's disease is characterized by accumulation of the aggregation-prone mutant Huntingtin (mHTT) protein. Here, we show that expression of exon 1 of mHTT in mouse cultured cells activates IRE1, the transmembrane sensor of stress in the endoplasmic reticulum, leading to degradation of the Blos1 mRNA and repositioning of lysosomes and late endosomes toward the microtubule organizing center. Overriding Blos1 degradation results in excessive accumulation of mHTT aggregates in both cultured cells and primary neurons. Although mHTT is degraded by macroautophagy when highly expressed, we show that before the formation of large aggregates, mHTT is degraded via an ESCRT-dependent, macroautophagy-independent pathway consistent with endosomal microautophagy. This pathway is enhanced by Blos1 degradation and appears to protect cells from a toxic, less aggregated form of mHTT.
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Affiliation(s)
- Donghwi Bae
- School of Biological Sciences and Center for Cell and Genome Science, and
| | | | | | - Mitali Tyagi
- Department of Neurobiology, School of Medicine, University of Utah, Salt Lake City, UT 84112
| | - Jason D. Shepherd
- Department of Neurobiology, School of Medicine, University of Utah, Salt Lake City, UT 84112
| | - Julie Hollien
- School of Biological Sciences and Center for Cell and Genome Science, and,*Address correspondence to: Julie Hollien ()
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The LDL receptor: Traffic and function in trophoblast cells under normal and pathological conditions. Placenta 2022; 127:12-19. [DOI: 10.1016/j.placenta.2022.07.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 07/11/2022] [Accepted: 07/15/2022] [Indexed: 12/18/2022]
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Mitochondrial GCN5L1 regulates cytosolic redox state and hepatic gluconeogenesis via glycerol phosphate shuttle GPD2. Biochem Biophys Res Commun 2022; 621:1-7. [DOI: 10.1016/j.bbrc.2022.06.092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/23/2022] [Accepted: 06/28/2022] [Indexed: 11/23/2022]
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Anderson J, Walker G, Pu J. BORC-ARL8-HOPS ensemble is required for lysosomal cholesterol egress through NPC2. Mol Biol Cell 2022; 33:ar81. [PMID: 35653304 PMCID: PMC9582633 DOI: 10.1091/mbc.e21-11-0595-t] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 05/16/2022] [Accepted: 05/24/2022] [Indexed: 11/11/2022] Open
Abstract
Lysosomes receive extracellular and intracellular cholesterol and redistribute it throughout the cell. Cholesterol egress from lysosomes is critical for cholesterol homeostasis, and its failure underlies the pathogenesis of genetic disorders such as Niemann-Pick C (NPC) disease. Here we report that the BLOC one-related complex (BORC)-ARL8-homotypic fusion and protein sorting (HOPS) ensemble is required for egress of free cholesterol from lysosomes and for storage of esterified cholesterol in lipid droplets. Depletion of BORC, ARL8, or HOPS does not alter the localization of the lysosomal transmembrane cholesterol transporter NPC1 to degradative compartments but decreases the association of the luminal transporter NPC2 and increases NPC2 secretion. BORC-ARL8-HOPS depletion also increases lysosomal degradation of cation-independent (CI)-mannose 6-phosphate (M6P) receptor (MPR), which normally sorts NPC2 to the endosomal-lysosomal system and then is recycled to the trans-Golgi network. These defects likely result from impaired HOPS-dependent fusion of endosomal-lysosomal organelles and an uncharacterized function of HOPS in CI-MPR recycling. Our study demonstrates that the BORC-ARL8-HOPS ensemble is required for cholesterol egress from lysosomes by enabling CI-MPR-dependent trafficking of NPC2 to the endosomal-lysosomal system.
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Affiliation(s)
- Jacob Anderson
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131
- Autophagy, Inflammation, and Metabolism Center of Biomedical Research Excellence, University of New Mexico, Albuquerque, NM 87131
| | - Gerard Walker
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Jing Pu
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131
- Autophagy, Inflammation, and Metabolism Center of Biomedical Research Excellence, University of New Mexico, Albuquerque, NM 87131
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Hu J, Zhu Z, Chen Z, Yang Q, Liang W, Ding G. Alteration in Rab11-mediated endocytic trafficking of LDL receptor contributes to angiotensin II-induced cholesterol accumulation and injury in podocytes. Cell Prolif 2022; 55:e13229. [PMID: 35567428 PMCID: PMC9201372 DOI: 10.1111/cpr.13229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/04/2022] [Accepted: 03/18/2022] [Indexed: 12/16/2022] Open
Abstract
Objectives Exposure of podocytes to angiotensin II (Ang II) enhances the abundance of the cell surface glycoprotein, low‐density lipoprotein receptor (LDLR) and promotes significant changes in the cellular cholesterol content. Recent investigation provides evidence that the small GTPase Rab11 is involved in the regulation of LDLR, but the exact mechanisms remain unknown. In this study, the role of Rab11 in post‐transcriptional regulation of LDLR was evaluated to investigate potential mechanisms of podocyte cholesterol dysregulation in chronic kidney disease. Materials and Methods Cholesterol content, LDLR and Rab11 expression were assessed in podocytes from Ang II‐infused mice. In vitro, the intracellular localization of LDLR was detected under different conditions. Rab11 expression was modulated and we then explored the effect of anti‐lipid cytotoxicity by detecting LDLR expression and trafficking, cholesterol content and apoptosis in podocytes. Results Cholesterol accumulation, upregulated expression of LDLR and Rab11 were discovered in podocytes from Ang II‐infused mice. Ang II enhanced the co‐precipitation of LDLR with Rab11 and accelerated the endocytic recycling of LDLR to the plasma membrane. Additionally, silencing Rab11 promoted lysosomal degradation of LDLR and alleviated Ang II‐induced cholesterol accumulation and apoptosis in podocytes. Conversely, overexpression of Rab11 or inhibition of lysosomal degradation up‐regulated the abundance of LDLR and aggravated podocyte cholesterol deposition. Conclusions Rab11 triggers the endocytic trafficking and recycling of LDLR; overactivation of this pathway contributes to Ang II‐induced podocyte cholesterol accumulation and injury.
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Affiliation(s)
- Jijia Hu
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Zijing Zhu
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Zhaowei Chen
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Qian Yang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Wei Liang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Guohua Ding
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
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