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Meurs A, Ndoj K, van den Berg M, Marinković G, Tantucci M, Veenendaal T, Kuivenhoven JA, Klumperman J, Zelcer N. A suite of genome-engineered hepatic cells provides novel insights into the spatiotemporal metabolism of apolipoprotein B and apolipoprotein B-containing lipoprotein secretion. Cardiovasc Res 2024; 120:1253-1264. [PMID: 38833612 PMCID: PMC11416059 DOI: 10.1093/cvr/cvae121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/29/2024] [Accepted: 04/18/2024] [Indexed: 06/06/2024] Open
Abstract
AIMS Apolipoprotein B (APOB)-containing very LDL (VLDL) production, secretion, and clearance by hepatocytes is a central determinant of hepatic and circulating lipid levels. Impairment of any of the aforementioned processes is associated with the development of multiple diseases. Despite the discovery of genes and processes that govern hepatic VLDL metabolism, our understanding of the different mechanistic steps involved is far from complete. An impediment to these studies is the lack of tractable hepatocyte-based systems to interrogate and follow APOB in cells, which the current study addresses. METHODS AND RESULTS To facilitate the cellular study of VLDL metabolism, we generated human hepatic HepG2 and Huh-7 cell lines in which CRISPR/Cas9-based genome engineering was used to introduce the fluorescent protein mNeonGreen into the APOB gene locus. This results in the production of APOB100-mNeon that localizes predominantly to the endoplasmic reticulum (ER) and Golgi by immunofluorescence and electron microscopy imaging. The production and secretion of APOB100-mNeon can be quantitatively followed in medium over time and results in the production of lipoproteins that are taken up via the LDL receptor pathway. Importantly, the production and secretion of APOB-mNeon is sensitive to established pharmacological and physiological treatments and to genetic modifiers known to influence VLDL production in humans. As a showcase, we used HepG2-APOBmNeon cells to interrogate ER-associated degradation of APOB. The use of a dedicated sgRNA library targeting all established membrane-associated ER-resident E3 ubiquitin ligases led to the identification of SYNV1 as the E3 responsible for the degradation of poorly lipidated APOB in HepG2 cells. CONCLUSIONS In summary, the engineered cells reported here allow the study of hepatic VLDL assembly and secretion and facilitate spatiotemporal interrogation induced by pharmacologic and genetic perturbations.
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Affiliation(s)
- Amber Meurs
- Department of Medical Biochemistry, Amsterdam UMC, Amsterdam Gastroenterology Endocrinology Metabolism and Amsterdam Cardiovascular Sciences, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands
| | - Klevis Ndoj
- Department of Medical Biochemistry, Amsterdam UMC, Amsterdam Gastroenterology Endocrinology Metabolism and Amsterdam Cardiovascular Sciences, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands
| | - Marlene van den Berg
- Department of Medical Biochemistry, Amsterdam UMC, Amsterdam Gastroenterology Endocrinology Metabolism and Amsterdam Cardiovascular Sciences, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands
| | - Goran Marinković
- Department of Medical Biochemistry, Amsterdam UMC, Amsterdam Gastroenterology Endocrinology Metabolism and Amsterdam Cardiovascular Sciences, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands
| | - Matteo Tantucci
- Center for Molecular Medicine—Cell Biology, University Medical Center Utrecht, University of Utrecht, Heidelberglaan 100, 3584CX Utrecht, The Netherlands
| | - Tineke Veenendaal
- Center for Molecular Medicine—Cell Biology, University Medical Center Utrecht, University of Utrecht, Heidelberglaan 100, 3584CX Utrecht, The Netherlands
| | - Jan Albert Kuivenhoven
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Judith Klumperman
- Center for Molecular Medicine—Cell Biology, University Medical Center Utrecht, University of Utrecht, Heidelberglaan 100, 3584CX Utrecht, The Netherlands
| | - Noam Zelcer
- Department of Medical Biochemistry, Amsterdam UMC, Amsterdam Gastroenterology Endocrinology Metabolism and Amsterdam Cardiovascular Sciences, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands
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van Zwol W, van de Sluis B, Ginsberg HN, Kuivenhoven JA. VLDL Biogenesis and Secretion: It Takes a Village. Circ Res 2024; 134:226-244. [PMID: 38236950 PMCID: PMC11284300 DOI: 10.1161/circresaha.123.323284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/21/2023] [Indexed: 01/23/2024]
Abstract
The production and secretion of VLDLs (very-low-density lipoproteins) by hepatocytes has a direct impact on liver fat content, as well as the concentrations of cholesterol and triglycerides in the circulation and thus affects both liver and cardiovascular health, respectively. Importantly, insulin resistance, excess caloric intake, and lack of physical activity are associated with overproduction of VLDL, hepatic steatosis, and increased plasma levels of atherogenic lipoproteins. Cholesterol and triglycerides in remnant particles generated by VLDL lipolysis are risk factors for atherosclerotic cardiovascular disease and have garnered increasing attention over the last few decades. Presently, however, increased risk of atherosclerosis is not the only concern when considering today's cardiometabolic patients, as they often also experience hepatic steatosis, a prevalent disorder that can progress to steatohepatitis and cirrhosis. This duality of metabolic risk highlights the importance of understanding the molecular regulation of the biogenesis of VLDL, the lipoprotein that transports triglycerides and cholesterol out of the liver. Fortunately, there has been a resurgence of interest in the intracellular assembly, trafficking, degradation, and secretion of VLDL by hepatocytes, which has led to many exciting new molecular insights that are the topic of this review. Increasing our understanding of the biology of this pathway will aid to the identification of novel therapeutic targets to improve both the cardiovascular and the hepatic health of cardiometabolic patients. This review focuses, for the first time, on this duality.
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Affiliation(s)
- Willemien van Zwol
- Department of Paediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Bart van de Sluis
- Department of Paediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Henry. N. Ginsberg
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Jan Albert Kuivenhoven
- Department of Paediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
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Zhang Y, Wang X, Chen G, Lu Y, Chen Q. Autocrine motility factor receptor promotes the malignancy of glioblastoma by regulating cell migration and invasion. Neurol Res 2024; 46:89-97. [PMID: 37703903 DOI: 10.1080/01616412.2023.2257463] [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: 05/04/2023] [Accepted: 07/30/2023] [Indexed: 09/15/2023]
Abstract
OBJECTIVE One of the important causes of death in cancer patients is malignant metastasis, invasion, and metastasis of tumor cells. Metastasis is also the most basic physiological characteristics and pathogenesis of various tumors. Previously published studies have suggested that autocrine motor factor receptor (AMFR) is the key regulator of tumor cell migration and invasion. Meanwhile, AMFR is highly expressed in esophageal tumors, gastrointestinal tumors, and bladder cancer, and it is also involved in its pathogenesis. However, the role of AMFR in glioblastoma has not been reported. METHODS In order to study the role of AMFR in the cell migration and invasion of glioblastoma, AMFR was silenced using siRNA and overexpressed using cDNA. Immunoblotting analysis and real-time quantitative polymerase chain reaction (PCR) were employed to assess the expression of AMFR. We conducted wound healing assay, cell migration assay, and tumorsphere formation assay to detect the invasion and metastatic ability of glioblastoma. RESULTS This study found that the level of AMFR expression was significantly correlated with the malignant degree of glioma tissue in clinic samples. AMFR silencing decreased cell migration and invasion of LN229. Overexpression of AMFR significantly increased cell migration and invasion of U251. CONCLUSION This study suggests that AMFR could be used as a therapeutic strategy for the clinical treatment of glioblastoma.
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Affiliation(s)
- Yao Zhang
- Department of Endocrinology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiuping Wang
- Department of Pharmacy, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guanghui Chen
- Department of Pharmacy, Renmin Hospital, Wuhan University, Wuhan, China
| | - Yajing Lu
- Institute of geriatric medicine, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qiang Chen
- Department of Pharmacy, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Erzurumlu Y, Dogan HK, Catakli D, Aydogdu E, Muhammed MT. Estrogens drive the endoplasmic reticulum-associated degradation and promote proto-oncogene c-Myc expression in prostate cancer cells by androgen receptor/estrogen receptor signaling. J Cell Commun Signal 2023; 17:793-811. [PMID: 36696010 PMCID: PMC10409964 DOI: 10.1007/s12079-022-00720-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 12/21/2022] [Indexed: 01/26/2023] Open
Abstract
The tumorigenic properties of prostate cancer are regulated by advanced hormonal regulation-mediated complex molecular signals. Therefore, characterizing the regulation of these signal transduction systems is crucial for understanding prostate cancer biology. Recent studies have shown that endoplasmic reticulum (ER)-localized protein quality control mechanisms, including ER-associated degradation (ERAD) and unfolded protein response (UPR) signaling contribute to prostate carcinogenesis and to the development of drug resistance. It has also been determined that these systems are tightly regulated by androgens. However, the role of estrogenic signaling in prostate cancer and its effects on protein quality control mechanisms is not fully understood. Herein, we investigated the regulatory effects of estrogens on ERAD and UPR and their impacts on prostate carcinogenesis. We found that estrogens strongly regulated the ERAD components and IRE1⍺ branch of UPR by Er⍺/β/AR axis. Besides, estrogenic signaling rigorously regulated the tumorigenicity of prostate cancer cells by promoting c-Myc expression and epithelial-mesenchymal transition (EMT). Moreover, estrogenic signal blockage significantly decreased the tumorigenic features of prostate cancer cells. Additionally, simultaneous inhibition of androgenic/estrogenic signals more efficiently inhibited tumorigenicity of prostate cancer cells, including proliferation, migration, invasion and colonial growth. Furthermore, computational-based molecular docking, molecular dynamics simulations and MMPBSA calculations supported the estrogenic stimulation of AR. Present findings suggested that ERAD components and IRE1⍺ signaling are tightly regulated by estrogen-stimulated AR and Er⍺/β. Our data suggest that treatment approaches targeting the co-inhibition of androgenic/estrogenic signals may pave the way for new treatment approaches to be developed for prostate cancer. The present model of the impact of estrogens on ERAD and UPR signaling in androgen-sensitive prostate cancer cells.
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Affiliation(s)
- Yalcin Erzurumlu
- Department of Biochemistry, Faculty of Pharmacy, Suleyman Demirel University, 32260 Isparta, Turkey
| | - Hatice Kubra Dogan
- Department of Bioengineering, Institute of Science, Suleyman Demirel University, 32260 Isparta, Turkey
| | - Deniz Catakli
- Department of Pharmacology, Faculty of Medicine, Suleyman Demirel University, 32260 Isparta, Turkey
| | - Esra Aydogdu
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Suleyman Demirel University, 32260 Isparta, Turkey
| | - Muhammed Tilahun Muhammed
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Suleyman Demirel University, 32260 Isparta, Turkey
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Doss EM, Moore JM, Harman BH, Doud EH, Rubenstein EM, Bernstein DA. Characterization of endoplasmic reticulum-associated degradation in the human fungal pathogen Candida albicans. PeerJ 2023; 11:e15897. [PMID: 37645016 PMCID: PMC10461541 DOI: 10.7717/peerj.15897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 07/24/2023] [Indexed: 08/31/2023] Open
Abstract
Background Candida albicans is the most prevalent human fungal pathogen. In immunocompromised individuals, C. albicans can cause serious systemic disease, and patients infected with drug-resistant isolates have few treatment options. The ubiquitin-proteasome system has not been thoroughly characterized in C. albicans. Research from other organisms has shown ubiquitination is important for protein quality control and regulated protein degradation at the endoplasmic reticulum (ER) via ER-associated protein degradation (ERAD). Methods Here we perform the first characterization, to our knowledge, of ERAD in a human fungal pathogen. We generated functional knockouts of C. albicans genes encoding three proteins predicted to play roles in ERAD, the ubiquitin ligases Hrd1 and Doa10 and the ubiquitin-conjugating enzyme Ubc7. We assessed the fitness of each mutant in the presence of proteotoxic stress, and we used quantitative tandem mass tag mass spectrometry to characterize proteomic alterations in yeast lacking each gene. Results Consistent with a role in protein quality control, yeast lacking proteins thought to contribute to ERAD displayed hypersensitivity to proteotoxic stress. Furthermore, each mutant displayed distinct proteomic profiles, revealing potential physiological ERAD substrates, co-factors, and compensatory stress response factors. Among candidate ERAD substrates are enzymes contributing to ergosterol synthesis, a known therapeutic vulnerability of C. albicans. Together, our results provide the first description of ERAD function in C. albicans, and, to our knowledge, any pathogenic fungus.
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Affiliation(s)
- Ellen M. Doss
- Department of Biology, Ball State University, Muncie, Indiana, United States
- Mode of Action and Resistance Management Center of Expertise, Corteva Agriscience, Indianapolis, Indiana, United States
| | - Joshua M. Moore
- Department of Biology, Ball State University, Muncie, Indiana, United States
| | - Bryce H. Harman
- Department of Biology, Ball State University, Muncie, Indiana, United States
| | - Emma H. Doud
- Center for Proteome Analysis, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Eric M. Rubenstein
- Department of Biology, Ball State University, Muncie, Indiana, United States
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Wu X, Xu M, Geng M, Chen S, Little PJ, Xu S, Weng J. Targeting protein modifications in metabolic diseases: molecular mechanisms and targeted therapies. Signal Transduct Target Ther 2023; 8:220. [PMID: 37244925 PMCID: PMC10224996 DOI: 10.1038/s41392-023-01439-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 03/01/2023] [Accepted: 04/06/2023] [Indexed: 05/29/2023] Open
Abstract
The ever-increasing prevalence of noncommunicable diseases (NCDs) represents a major public health burden worldwide. The most common form of NCD is metabolic diseases, which affect people of all ages and usually manifest their pathobiology through life-threatening cardiovascular complications. A comprehensive understanding of the pathobiology of metabolic diseases will generate novel targets for improved therapies across the common metabolic spectrum. Protein posttranslational modification (PTM) is an important term that refers to biochemical modification of specific amino acid residues in target proteins, which immensely increases the functional diversity of the proteome. The range of PTMs includes phosphorylation, acetylation, methylation, ubiquitination, SUMOylation, neddylation, glycosylation, palmitoylation, myristoylation, prenylation, cholesterylation, glutathionylation, S-nitrosylation, sulfhydration, citrullination, ADP ribosylation, and several novel PTMs. Here, we offer a comprehensive review of PTMs and their roles in common metabolic diseases and pathological consequences, including diabetes, obesity, fatty liver diseases, hyperlipidemia, and atherosclerosis. Building upon this framework, we afford a through description of proteins and pathways involved in metabolic diseases by focusing on PTM-based protein modifications, showcase the pharmaceutical intervention of PTMs in preclinical studies and clinical trials, and offer future perspectives. Fundamental research defining the mechanisms whereby PTMs of proteins regulate metabolic diseases will open new avenues for therapeutic intervention.
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Affiliation(s)
- Xiumei Wu
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-sen University, 510000, Guangzhou, China
| | - Mengyun Xu
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Mengya Geng
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Shuo Chen
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Peter J Little
- School of Pharmacy, University of Queensland, Pharmacy Australia Centre of Excellence, Woolloongabba, QLD, 4102, Australia
- Sunshine Coast Health Institute and School of Health and Behavioural Sciences, University of the Sunshine Coast, Birtinya, QLD, 4575, Australia
| | - Suowen Xu
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Jianping Weng
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Clinical Research Hospital of Chinese Academy of Sciences (Hefei), University of Science and Technology of China, Hefei, Anhui, 230001, China.
- Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-sen University, 510000, Guangzhou, China.
- Bengbu Medical College, Bengbu, 233000, China.
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Erzurumlu Y, Catakli D, Dogan HK. Circadian Oscillation Pattern of Endoplasmic Reticulum Quality Control (ERQC) Components in Human Embryonic Kidney HEK293 Cells. J Circadian Rhythms 2023; 21:1. [PMID: 37033333 PMCID: PMC10077977 DOI: 10.5334/jcr.219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 03/14/2023] [Indexed: 04/05/2023] Open
Abstract
The circadian clock regulates the “push-pull” of the molecular signaling mechanisms that arrange the rhythmic organization of the physiology to maintain cellular homeostasis. In mammals, molecular clock genes tightly arrange cellular rhythmicity. It has been shown that this circadian clock optimizes various biological processes, including the cell cycle and autophagy. Hence, we explored the dynamic crosstalks between the circadian rhythm and endoplasmic reticulum (ER)-quality control (ERQC) mechanisms. ER-associated degradation (ERAD) is one of the most important parts of the ERQC system and is an elaborate surveillance system that eliminates misfolded proteins. It regulates the steady-state levels of several physiologically crucial proteins, such as 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and the metastasis suppressor KAI1/CD82. However, the circadian oscillation of ERQC members and their roles in cellular rhythmicity requires further investigation. In the present study, we provided a thorough investigation of the circadian rhythmicity of the fifteen crucial ERQC members, including gp78, Hrd1, p97/VCP, SVIP, Derlin1, Ufd1, Npl4, EDEM1, OS9, XTP3B, Sel1L, Ufd2, YOD1, VCIP135 and FAM8A1 in HEK293 cells. We found that mRNA and protein accumulation of the ubiquitin conjugation, binding and processing factors, retrotranslocation-dislocation, substrate recognition and targeting components of ERQC exhibit oscillation under the control of the circadian clock. Moreover, we found that Hrd1 and gp78 have a possible regulatory function on Bmal1 turnover. The findings of the current study indicated that the expression level of ERQC components is fine-tuned by the circadian clock and major ERAD E3 ligases, Hrd1 and gp78, may influence the regulation of circadian oscillation by modulation of Bmal1 stability.
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Lin H, Wang L, Liu Z, Long K, Kong M, Ye D, Chen X, Wang K, Wu KKL, Fan M, Song E, Wang C, Hoo RLC, Hui X, Hallenborg P, Piao H, Xu A, Cheng KKY. Hepatic MDM2 Causes Metabolic Associated Fatty Liver Disease by Blocking Triglyceride-VLDL Secretion via ApoB Degradation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200742. [PMID: 35524581 PMCID: PMC9284139 DOI: 10.1002/advs.202200742] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/15/2022] [Indexed: 05/06/2023]
Abstract
Dysfunctional triglyceride-very low-density lipoprotein (TG-VLDL) metabolism is linked to metabolic-associated fatty liver disease (MAFLD); however, the underlying cause remains unclear. The study shows that hepatic E3 ubiquitin ligase murine double minute 2 (MDM2) controls MAFLD by blocking TG-VLDL secretion. A remarkable upregulation of MDM2 is observed in the livers of human and mouse models with different levels of severity of MAFLD. Hepatocyte-specific deletion of MDM2 protects against high-fat high-cholesterol diet-induced hepatic steatosis and inflammation, accompanied by a significant elevation in TG-VLDL secretion. As an E3 ubiquitin ligase, MDM2 targets apolipoprotein B (ApoB) for proteasomal degradation through direct protein-protein interaction, which leads to reduced TG-VLDL secretion in hepatocytes. Pharmacological blockage of the MDM2-ApoB interaction alleviates dietary-induced hepatic steatohepatitis and fibrosis by inducing hepatic ApoB expression and subsequent TG-VLDL secretion. The effect of MDM2 on VLDL metabolism is p53-independent. Collectively, these findings suggest that MDM2 acts as a negative regulator of hepatic ApoB levels and TG-VLDL secretion in MAFLD. Inhibition of the MDM2-ApoB interaction may represent a potential therapeutic approach for MAFLD treatment.
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Affiliation(s)
- Huige Lin
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong
| | - Lin Wang
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong
- The State Key Laboratory of Pharmaceutical BiotechnologyThe University of Hong KongPokfulamHong Kong
- Department of MedicineThe University of Hong KongPokfulamHong Kong
| | - Zhuohao Liu
- The State Key Laboratory of Pharmaceutical BiotechnologyThe University of Hong KongPokfulamHong Kong
- Department of MedicineThe University of Hong KongPokfulamHong Kong
- Department of NeurosurgeryShenzhen HospitalSouthern Medical UniversityShenzhen518000P. R. China
| | - Kekao Long
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong
| | - Mengjie Kong
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong
| | - Dewei Ye
- Key Laboratory of Glucolipid Metabolic Diseases of the Ministry of EducationGuangdong Pharmaceutical UniversityGuangzhou510000P. R. China
| | - Xi Chen
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong
| | - Kai Wang
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong
| | - Kelvin KL Wu
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong
| | - Mengqi Fan
- Key Laboratory of Glucolipid Metabolic Diseases of the Ministry of EducationGuangdong Pharmaceutical UniversityGuangzhou510000P. R. China
| | - Erfei Song
- Department of Metabolic and Bariatric SurgeryThe First Affiliated Hospital of Jinan UniversityGuangzhou510000P. R. China
| | - Cunchuan Wang
- Department of Metabolic and Bariatric SurgeryThe First Affiliated Hospital of Jinan UniversityGuangzhou510000P. R. China
| | - Ruby LC Hoo
- The State Key Laboratory of Pharmaceutical BiotechnologyThe University of Hong KongPokfulamHong Kong
- Department of Pharmacology and PharmacyThe University of Hong KongPokfulamHong Kong
| | - Xiaoyan Hui
- The State Key Laboratory of Pharmaceutical BiotechnologyThe University of Hong KongPokfulamHong Kong
- Department of MedicineThe University of Hong KongPokfulamHong Kong
| | - Philip Hallenborg
- Department of Biochemistry and Molecular BiologyUniversity of Southern DenmarkSouthern Denmark5230Denmark
| | - Hailong Piao
- Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian116000P. R. China
| | - Aimin Xu
- The State Key Laboratory of Pharmaceutical BiotechnologyThe University of Hong KongPokfulamHong Kong
- Department of MedicineThe University of Hong KongPokfulamHong Kong
- Department of Pharmacology and PharmacyThe University of Hong KongPokfulamHong Kong
| | - Kenneth KY Cheng
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong
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Chen X, Jiang L, Zhou Z, Yang B, He Q, Zhu C, Cao J. The Role of Membrane-Associated E3 Ubiquitin Ligases in Cancer. Front Pharmacol 2022; 13:928794. [PMID: 35847032 PMCID: PMC9285105 DOI: 10.3389/fphar.2022.928794] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 06/10/2022] [Indexed: 11/13/2022] Open
Abstract
The cell membrane system comprises the plasma membrane, endoplasmic reticulum, Golgi apparatus, lysosome, mitochondria, and nuclear membrane, which are essential for maintaining normal physiological functions of cells. The proteins associated with these membrane-organelles are frequently modified to regulate their functions, the most common of which is ubiquitin modification. So far, many ubiquitin E3 ligases anchored in the membrane system have been identified as critical players facilitating intracellular biofunctions whose dysfunction is highly related to cancer. In this review, we summarized membrane-associated E3 ligases and revealed their relationship with cancer, which is of great significance for discovering novel drug targets of cancer and may open up new avenues for inducing ubiquitination-mediated degradation of cancer-associated membrane proteins via small chemicals such as PROTAC and molecular glue.
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Affiliation(s)
- Xuankun Chen
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Institute of Pharmacology and Toxicology, Zhejiang University, Hangzhou, China
| | - Li Jiang
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Institute of Pharmacology and Toxicology, Zhejiang University, Hangzhou, China
| | - Zhesheng Zhou
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Institute of Pharmacology and Toxicology, Zhejiang University, Hangzhou, China
| | - Bo Yang
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Institute of Pharmacology and Toxicology, Zhejiang University, Hangzhou, China
- The Innovation Institute for Artificial Intelligence in Medicine, Zhejiang University, Hangzhou, China
| | - Qiaojun He
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Institute of Pharmacology and Toxicology, Zhejiang University, Hangzhou, China
- The Innovation Institute for Artificial Intelligence in Medicine, Zhejiang University, Hangzhou, China
- Center for Drug Safety Evaluation and Research of Zhejiang University, Zhejiang University, Hangzhou, China
- Cancer Center of Zhejiang University, Hangzhou, China
| | - Chengliang Zhu
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Institute of Pharmacology and Toxicology, Zhejiang University, Hangzhou, China
- The Innovation Institute for Artificial Intelligence in Medicine, Zhejiang University, Hangzhou, China
- Center for Drug Safety Evaluation and Research of Zhejiang University, Zhejiang University, Hangzhou, China
- *Correspondence: Chengliang Zhu, ; Ji Cao,
| | - Ji Cao
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Institute of Pharmacology and Toxicology, Zhejiang University, Hangzhou, China
- The Innovation Institute for Artificial Intelligence in Medicine, Zhejiang University, Hangzhou, China
- Cancer Center of Zhejiang University, Hangzhou, China
- *Correspondence: Chengliang Zhu, ; Ji Cao,
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Singhal SK, Byun JS, Yan T, Yancey R, Caban A, Gil Hernandez S, Bufford S, Hewitt SM, Winfield J, Pradhan JS, Mustkov V, McDonald JA, Pérez-Stable EJ, Napoles AM, Vohra N, De Siervi A, Yates C, Davis MB, Yang M, Tsai YC, Weissman AM, Gardner K. Protein expression of the gp78 E3-ligase predicts poor breast cancer outcome based on race. JCI Insight 2022; 7:157465. [PMID: 35639484 PMCID: PMC9310521 DOI: 10.1172/jci.insight.157465] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 05/20/2022] [Indexed: 11/17/2022] Open
Abstract
Women of African ancestry suffer higher rates of breast cancer mortality compared to all other groups in the United States. Though the precise reasons for these disparities remain unclear, many recent studies have implicated a role for differences in tumor biology. Using an epitope-validated antibody against the endoplasmic reticulum-associated degradation (ERAD) E3 ubiquitin ligase, gp78, we show that elevated levels of gp78 in patient breast cancer cells predict poor survival. Moreover, high levels of gp78 are associated with poor outcomes in both ER-positive and ER-negative tumors, and breast cancers expressing elevated amounts of gp78 protein are enriched in gene expression pathways that influence cell cycle, metabolism, receptor-mediated signaling, and cell stress response pathways. In multivariate analysis adjusted for subtype and grade, gp78 protein is an independent predictor of poor outcomes in women of African ancestry. Furthermore, gene expression signatures, derived from patients stratified by gp78 protein expression, are strong predictors of recurrence and pathological complete response in retrospective clinical trial data and share many common features with gene sets previously identified to be overrepresented in breast cancers based on race. These findings implicate a prominent role for gp78 in tumor progression and offer new insights into our understanding of racial differences in breast cancer outcomes.
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Affiliation(s)
- Sandeep K Singhal
- Department of Pathology, University of North Dakota, Grand Forks, United States of America
| | - Jung S Byun
- Intramural Research Program, National Institutes of Minority Health and Health Disparities, Bethesda, United States of America
| | - Tingfen Yan
- Intramural Research Program, National Institutes of Minority Health and Health Disparities, Bethesda, United States of America
| | - Ryan Yancey
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States of America
| | - Ambar Caban
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States of America
| | - Sara Gil Hernandez
- Intramural Research Program, National Institutes of Minority Health and Health Disparities, Bethesda, United States of America
| | - Sediqua Bufford
- Masters of Science Biotechnology, Morehouse School of Medicine, Atlanta, United States of America
| | - Stephen M Hewitt
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, United States of America
| | - Joy Winfield
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States of America
| | - Jaya Sarin Pradhan
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States of America
| | - Vesco Mustkov
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States of America
| | - Jasmine A McDonald
- Department of Epidemiology, Columbia University Medical Center, New York, United States of America
| | - Eliseo J Pérez-Stable
- Intramural Research Program, National Institutes of Minority Health and Health Disparities, Bethesda, United States of America
| | - Anna Maria Napoles
- Intramural Research Program, National Institutes of Minority Health and Health Disparities, Bethesda, United States of America
| | - Nasreen Vohra
- Brody School of Medicine, East Carolina University, Greenville, United States of America
| | - Adriana De Siervi
- Directora del Laboratorio de Oncología Molecular y Nuevos Blancos Terapéut, CONICET, Buenos Aiers, Argentina
| | - Clayton Yates
- Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, United States of America
| | - Melissa B Davis
- Department of Surgery (Breast Surgery & Oncology), Weill Cornell Medicine, New York, United States of America
| | - Mei Yang
- Laboratory of Protein Dynamics and Signaling, National Cancer Institute, Frederick, United States of America
| | - Yien Che Tsai
- Laboratory of Protein Dynamics and Signaling, National Cancer Institute, Frederick, United States of America
| | - Allan M Weissman
- Laboratory of Protein Dynamics and Signaling, National Cancer Institute, Frederick, United States of America
| | - Kevin Gardner
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States of America
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11
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Ilhan R, Üner G, Yilmaz S, Atalay Sahar E, Cayli S, Erzurumlu Y, Gozen O, Ballar Kirmizibayrak P. Novel regulation mechanism of adrenal cortisol and DHEA biosynthesis via the endogen ERAD inhibitor small VCP-interacting protein. Sci Rep 2022; 12:869. [PMID: 35042898 PMCID: PMC8766438 DOI: 10.1038/s41598-022-04821-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 12/31/2021] [Indexed: 12/26/2022] Open
Abstract
Endoplasmic reticulum-associated degradation (ERAD) is a well-characterized mechanism of protein quality control by removal of misfolded or unfolded proteins. The tight regulation of ERAD is critical for protein homeostasis as well as lipid metabolism. Although the mechanism is complex, all ERAD branches converge on p97/VCP, a key protein in the retrotranslocation step. The multifunctionality of p97/VCP relies on its multiple binding partners, one of which is the endogenous ERAD inhibitor, SVIP (small VCP-interacting protein). As SVIP is a promising target for the regulation of ERAD, we aimed to assess its novel physiological roles. We revealed that SVIP is highly expressed in the rat adrenal gland, especially in the cortex region, at a consistently high level during postnatal development, unlike the gradual increase in expression seen in developing nerves. Steroidogenic stimulators caused a decrease in SVIP mRNA expression and increase in SVIP protein degradation in human adrenocortical H295R cells. Interestingly, silencing of SVIP diminished cortisol secretion along with downregulation of steroidogenic enzymes and proteins involved in cholesterol uptake and cholesterol biosynthesis. A certain degree of SVIP overexpression mainly increased the biosynthesis of cortisol as well as DHEA by enhancing the expression of key steroidogenic proteins, whereas exaggerated overexpression led to apoptosis, phosphorylation of eIF2α, and diminished adrenal steroid hormone biosynthesis. In conclusion, SVIP is a novel regulator of adrenal cortisol and DHEA biosynthesis, suggesting that alterations in SVIP expression levels may be involved in the deregulation of steroidogenic stimulator signaling and abnormal adrenal hormone secretion.
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Affiliation(s)
- Recep Ilhan
- Department of Biochemistry, Faculty of Pharmacy, Ege University, 35100, Bornova, Izmir, Turkey
| | - Göklem Üner
- Department of Bioengineering, Izmir Institute of Technology, 35430, Urla, Izmir, Turkey
| | - Sinem Yilmaz
- Department of Biotechnology, Graduate School of Natural and Applied Sciences, Ege University, Izmir, Turkey
- Department of Bioengineering, Faculty of Engineering, University of Alanya Aladdin Keykubat, Antalya, Turkey
| | - Esra Atalay Sahar
- Department of Biotechnology, Graduate School of Natural and Applied Sciences, Ege University, Izmir, Turkey
| | - Sevil Cayli
- Department of Histology and Embryology, Medical Faculty, Ankara Yıldırım Beyazıt University, Ankara, Turkey
| | - Yalcin Erzurumlu
- Department of Biochemistry, Faculty of Pharmacy, Ege University, 35100, Bornova, Izmir, Turkey
- Suleyman Demirel University, Faculty of Pharmacy, Isparta, Turkey
| | - Oguz Gozen
- Department of Physiology, School of Medicine, Ege University, Izmir, Turkey
| | - Petek Ballar Kirmizibayrak
- Department of Biochemistry, Faculty of Pharmacy, Ege University, 35100, Bornova, Izmir, Turkey.
- Department of Biotechnology, Graduate School of Natural and Applied Sciences, Ege University, Izmir, Turkey.
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12
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Kumari D, Fisher EA, Brodsky JL. Hsp40s play distinct roles during the initial stages of apolipoprotein B biogenesis. Mol Biol Cell 2021; 33:ar15. [PMID: 34910568 PMCID: PMC9236142 DOI: 10.1091/mbc.e21-09-0436] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Apolipoprotein B (ApoB) is the primary component of atherogenic lipoproteins, which transport serum fats and cholesterol. Therefore, elevated levels of circulating ApoB are a primary risk factor for cardiovascular disease. During ApoB biosynthesis in the liver and small intestine under nutrient-rich conditions, ApoB cotranslationally translocates into the endoplasmic reticulum (ER) and is lipidated and ultimately secreted. Under lipid-poor conditions, ApoB is targeted for ER Associated Degradation (ERAD). Although prior work identified select chaperones that regulate ApoB biogenesis, the contributions of cytoplasmic Hsp40s are undefined. To this end, we screened ApoB-expressing yeast and determined that a class A ER-associated Hsp40, Ydj1, associates with and facilitates the ERAD of ApoB. Consistent with these results, a homologous Hsp40, DNAJA1, functioned similarly in rat hepatoma cells. DNAJA1 deficient cells also secreted hyperlipidated lipoproteins, in accordance with attenuated ERAD. In contrast to the role of DNAJA1 during ERAD, DNAJB1-a class B Hsp40-helped stabilize ApoB. Depletion of DNAJA1 and DNAJB1 also led to opposing effects on ApoB ubiquitination. These data represent the first example in which different Hsp40s exhibit disparate effects during regulated protein biogenesis in the ER, and highlight distinct roles that chaperones can play on a single ERAD substrate.
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Affiliation(s)
- Deepa Kumari
- Department of Biological Sciences, A320 Langley Hall, Fifth & Ruskin Ave, University of Pittsburgh, Pittsburgh, PA 15260 USA
| | - Edward A Fisher
- Department of Medicine, Leon H. Charney Division of Cardiology, Cardiovascular Research Center, New York University Grossman School of Medicine, New York, United States
| | - Jeffrey L Brodsky
- Department of Biological Sciences, A320 Langley Hall, Fifth & Ruskin Ave, University of Pittsburgh, Pittsburgh, PA 15260 USA
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13
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Wang B, Zhu Y, Yu C, Zhang C, Tang Q, Huang H, Zhao Z. Hepatitis C virus induces oxidation and degradation of apolipoprotein B to enhance lipid accumulation and promote viral production. PLoS Pathog 2021; 17:e1009889. [PMID: 34492079 PMCID: PMC8448335 DOI: 10.1371/journal.ppat.1009889] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 09/17/2021] [Accepted: 08/14/2021] [Indexed: 12/14/2022] Open
Abstract
Hepatitis C virus (HCV) infection induces the degradation and decreases the secretion of apolipoprotein B (ApoB). Impaired production and secretion of ApoB-containing lipoprotein is associated with an increase in hepatic steatosis. Therefore, HCV infection-induced degradation of ApoB may contribute to hepatic steatosis and decreased lipoprotein secretion, but the mechanism of HCV infection-induced ApoB degradation has not been completely elucidated. In this study, we found that the ApoB level in HCV-infected cells was regulated by proteasome-associated degradation but not autophagic degradation. ApoB was degraded by the 20S proteasome in a ubiquitin-independent manner. HCV induced the oxidation of ApoB via oxidative stress, and oxidized ApoB was recognized by the PSMA5 and PSMA6 subunits of the 20S proteasome for degradation. Further study showed that ApoB was degraded at endoplasmic reticulum (ER)-associated lipid droplets (LDs) and that the retrotranslocation and degradation of ApoB required Derlin-1 but not gp78 or p97. Moreover, we found that knockdown of ApoB before infection increased the cellular lipid content and enhanced HCV assembly. Overexpression of ApoB-50 inhibited lipid accumulation and repressed viral assembly in HCV-infected cells. Our study reveals a novel mechanism of ApoB degradation and lipid accumulation during HCV infection and might suggest new therapeutic strategies for hepatic steatosis. Hepatitis C virus (HCV) infection induces the degradation of apolipoprotein B (ApoB), which is the primary apolipoprotein in low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL). Impaired production and secretion of ApoB-containing lipoprotein is associated with an increase in hepatic steatosis. Thus, ApoB degradation might contribute to HCV infection-induced fatty liver. Here, we found that ApoB was not degraded through endoplasmic reticulum-associated degradation (ERAD) or autophagy, as reported previously. Instead, HCV infection induced ApoB oxidation through oxidative stress, and oxidatively damaged ApoB could be recognized and directly degraded by the 20S proteasome. We also found that ApoB was retrotranslocated from the endoplasmic reticulum (ER) to lipid droplets (LDs) for degradation. Through overexpression of ApoB-50, which can mediate the assembly and secretion of LDL and VLDL, we confirmed that ApoB degradation contributed to hepatocellular lipid accumulation induced by HCV infection. Additionally, expression of ApoB-50 impaired HCV production due to the observed decrease in lipid accumulation. In this study, we identified new mechanisms of ApoB degradation and HCV-induced lipid accumulation, and our findings might facilitate the development of novel therapeutic strategies for HCV infection-induced fatty liver.
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Affiliation(s)
- Bei Wang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Clinical Immunology Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yue Zhu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Congci Yu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Chongyang Zhang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Qing Tang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - He Huang
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Clinical Immunology Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- * E-mail:
| | - Zhendong Zhao
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Clinical Immunology Center, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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14
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Wu JX, He KY, Zhang ZZ, Qu YL, Su XB, Shi Y, Wang N, Wang L, Han ZG. LZP is required for hepatic triacylglycerol transportation through maintaining apolipoprotein B stability. PLoS Genet 2021; 17:e1009357. [PMID: 33591966 PMCID: PMC7909667 DOI: 10.1371/journal.pgen.1009357] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 02/26/2021] [Accepted: 01/12/2021] [Indexed: 12/12/2022] Open
Abstract
The conserved zona pellucida (ZP) domain is found in hundreds of extracellular proteins that are expressed in various organs and play a variety of roles as structural components, receptors and tumor suppressors. A liver-specific zona pellucida domain-containing protein (LZP), also named OIT3, has been shown to be mainly expressed in human and mouse hepatocytes; however, the physiological function of LZP in the liver remains unclear. Here, we show that Lzp deletion inhibited very low-density lipoprotein (VLDL) secretion, leading to hepatic TG accumulation and lower serum TG levels in mice. The apolipoprotein B (apoB) levels were significantly decreased in the liver, serum, and VLDL particles of LZP-deficient mice. In the presence of LZP, which is localized to the endoplasmic reticulum (ER) and Golgi apparatus, the ER-associated degradation (ERAD) of apoB was attenuated; in contrast, in the absence of LZP, apoB was ubiquitinated by AMFR, a known E3 ubiquitin ligase specific for apoB, and was subsequently degraded, leading to lower hepatic apoB levels and inhibited VLDL secretion. Interestingly, hepatic LZP levels were elevated in mice challenged with a high-fat diet and humans with simple hepatic steatosis, suggesting that LZP contributes to the physiological regulation of hepatic TG homeostasis. In general, our data establish an essential role for LZP in hepatic TG transportation and VLDL secretion by preventing the AMFR-mediated ubiquitination and degradation of apoB and therefore provide insight into the molecular function of LZP in hepatic lipid metabolism.
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Affiliation(s)
- Jiao-Xiang Wu
- Key Laboratory of Systems Biomedicine (Ministry of Education) and Collaborative Innovation Center of Systems Biomedicine of Rui-Jin Hospital, Hongqiao International Institute of Medicine, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai-MOST Key Laboratory for Disease and Health Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Kun-Yan He
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhuang-Zhuang Zhang
- Key Laboratory of Systems Biomedicine (Ministry of Education) and Collaborative Innovation Center of Systems Biomedicine of Rui-Jin Hospital, Hongqiao International Institute of Medicine, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yu-Lan Qu
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xian-Bin Su
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yi Shi
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Na Wang
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lan Wang
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ze-Guang Han
- Key Laboratory of Systems Biomedicine (Ministry of Education) and Collaborative Innovation Center of Systems Biomedicine of Rui-Jin Hospital, Hongqiao International Institute of Medicine, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai-MOST Key Laboratory for Disease and Health Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
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15
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Mookherjee D, Das S, Mukherjee R, Bera M, Jana SC, Chakrabarti S, Chakrabarti O. RETREG1/FAM134B mediated autophagosomal degradation of AMFR/GP78 and OPA1 -a dual organellar turnover mechanism. Autophagy 2020; 17:1729-1752. [PMID: 32559118 DOI: 10.1080/15548627.2020.1783118] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Turnover of cellular organelles, including endoplasmic reticulum (ER) and mitochondria, is orchestrated by an efficient cellular surveillance system. We have identified a mechanism for dual regulation of ER and mitochondria under stress. It is known that AMFR, an ER E3 ligase and ER-associated degradation (ERAD) regulator, degrades outer mitochondrial membrane (OMM) proteins, MFNs (mitofusins), via the proteasome and triggers mitophagy. We show that destabilized mitochondria are almost devoid of the OMM and generate "mitoplasts". This brings the inner mitochondrial membrane (IMM) in the proximity of the ER. When AMFR levels are high and the mitochondria are stressed, the reticulophagy regulatory protein RETREG1 participates in the formation of the mitophagophore by interacting with OPA1. Interestingly, OPA1 and other IMM proteins exhibit similar RETREG1-dependent autophagosomal degradation as AMFR, unlike most of the OMM proteins. The "mitoplasts" generated are degraded by reticulo-mito-phagy - simultaneously affecting dual organelle turnover.Abbreviations: AMFR/GP78: autocrine motility factor receptor; BAPTA: 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; BFP: blue fluorescent protein; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; CNBr: cyanogen bromide; ER: endoplasmic reticulum; ERAD: endoplasmic-reticulum-associated protein degradation; FL: fluorescence, GFP: green fluorescent protein; HA: hemagglutinin; HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; IMM: inner mitochondrial membrane; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MFN: mitofusin, MGRN1: mahogunin ring finger 1; NA: numerical aperature; OMM: outer mitochondrial membrane; OPA1: OPA1 mitochondrial dynamin like GTPase; PRNP/PrP: prion protein; RER: rough endoplasmic reticulum; RETREG1/FAM134B: reticulophagy regulator 1; RFP: red fluorescent protein; RING: really interesting new gene; ROI: region of interest; RTN: reticulon; SEM: standard error of the mean; SER: smooth endoplasmic reticulum; SIM: structured illumination microscopy; SQSTM1/p62: sequestosome 1; STED: stimulated emission depletion; STOML2: stomatin like 2; TOMM20: translocase of outer mitochondrial membrane 20; UPR: unfolded protein response.
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Affiliation(s)
- Debdatto Mookherjee
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Subhrangshu Das
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Rukmini Mukherjee
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.,Buchmann Institute for Molecular Life Sciences, Frankfurt Am Main, Germany
| | - Manindra Bera
- Laboratory of Cell Biology, the Rockefeller University, New York, USA
| | | | - Saikat Chakrabarti
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.,Homi Bhabha National Institute, Mumbai, India
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16
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Kwon D, Kim SM, Correia MA. Cytochrome P450 endoplasmic reticulum-associated degradation (ERAD): therapeutic and pathophysiological implications. Acta Pharm Sin B 2020; 10:42-60. [PMID: 31993306 PMCID: PMC6976991 DOI: 10.1016/j.apsb.2019.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 02/07/2023] Open
Abstract
The hepatic endoplasmic reticulum (ER)-anchored cytochromes P450 (P450s) are mixed-function oxidases engaged in the biotransformation of physiologically relevant endobiotics as well as of myriad xenobiotics of therapeutic and environmental relevance. P450 ER-content and hence function is regulated by their coordinated hemoprotein syntheses and proteolytic turnover. Such P450 proteolytic turnover occurs through a process known as ER-associated degradation (ERAD) that involves ubiquitin-dependent proteasomal degradation (UPD) and/or autophagic-lysosomal degradation (ALD). Herein, on the basis of available literature reports and our own recent findings of in vitro as well as in vivo experimental studies, we discuss the therapeutic and pathophysiological implications of altered P450 ERAD and its plausible clinical relevance. We specifically (i) describe the P450 ERAD-machinery and how it may be repurposed for the generation of antigenic P450 peptides involved in P450 autoantibody pathogenesis in drug-induced acute hypersensitivity reactions and liver injury, or viral hepatitis; (ii) discuss the relevance of accelerated or disrupted P450-ERAD to the pharmacological and/or toxicological effects of clinically relevant P450 drug substrates; and (iii) detail the pathophysiological consequences of disrupted P450 ERAD, contributing to non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) under certain synergistic cellular conditions.
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Key Words
- 3MA, 3-methyladenine
- AAA, ATPases associated with various cellular activities
- ACC1, acetyl-CoA carboxylase 1
- ACC2, acetyl-CoA carboxylase 2
- ACHE, acetylcholinesterase
- ACOX1, acyl-CoA oxidase 1
- ALD, autophagic-lysosomal degradation
- AMPK1
- AP-1, activator protein 1
- ASK1, apoptosis signal-regulating kinase
- ATF2, activating transcription factor 2
- AdipoR1, gene of adiponectin receptor 1
- Atg14, autophagy-related 14
- CBZ, carbamazepine
- CHIP E3 ubiquitin ligase
- CHIP, carboxy-terminus of Hsc70-interacting protein
- Cytochromes P450
- Endoplasmic reticulum-associated degradation
- FOXO, forkhead box O
- Fas, fatty acid synthase
- GAPDH, glyceraldehyde 3-phosphate dehydrogenase
- INH, isoniazid
- IRS1, insulin receptor substrate 1
- Il-1β, interleukin 1 β
- Il-6, interleukin 6
- Insig1, insulin-induced gene 1
- JNK1
- Lpl, lipoprotein lipase
- Mcp1, chemokine (C–C motif) ligand 1
- Non-alcoholic fatty liver disease
- Non-alcoholic steatohepatitis
- Pgc1, peroxisome proliferator-activated receptor coactivator 1
- SREBP1c, sterol regulatory element binding transcription factor 1c
- Scd1, stearoyl-coenzyme A desaturase
- Tnf, tumor necrosis factor
- UPD, ubiquitin (Ub)-dependent proteasomal degradation
- Ub, ubiquitin
- gp78/AMFR E3 ubiquitin ligase
- gp78/AMFR, autocrine motility factor receptor
- shRNAi, shRNA interference
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17
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Koerner CM, Roberts BS, Neher SB. Endoplasmic reticulum quality control in lipoprotein metabolism. Mol Cell Endocrinol 2019; 498:110547. [PMID: 31442546 PMCID: PMC6814580 DOI: 10.1016/j.mce.2019.110547] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/16/2019] [Accepted: 08/17/2019] [Indexed: 12/26/2022]
Abstract
Lipids play a critical role in energy metabolism, and a suite of proteins is required to deliver lipids to tissues. Several of these proteins require an intricate endoplasmic reticulum (ER) quality control (QC) system and unique secondary chaperones for folding. Key examples include apolipoprotein B (apoB), which is the primary scaffold for many lipoproteins, dimeric lipases, which hydrolyze triglycerides from circulating lipoproteins, and the low-density lipoprotein receptor (LDLR), which clears cholesterol-rich lipoproteins from the circulation. ApoB requires specialized proteins for lipidation, dimeric lipases lipoprotein lipase (LPL) and hepatic lipase (HL) require a transmembrane maturation factor for secretion, and the LDLR requires several specialized, domain-specific chaperones. Deleterious mutations in these proteins or their chaperones may result in dyslipidemias, which are detrimental to human health. Here, we review the ER quality control systems that ensure secretion of apoB, LPL, HL, and LDLR with a focus on the specialized chaperones required by each protein.
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Affiliation(s)
- Cari M Koerner
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, USA
| | - Benjamin S Roberts
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, USA
| | - Saskia B Neher
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, USA.
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18
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Kwon D, Kim SM, Jacob P, Liu Y, Correia MA. Induction via Functional Protein Stabilization of Hepatic Cytochromes P450 upon gp78/Autocrine Motility Factor Receptor (AMFR) Ubiquitin E3-Ligase Genetic Ablation in Mice: Therapeutic and Toxicological Relevance. Mol Pharmacol 2019; 96:641-654. [PMID: 31492698 DOI: 10.1124/mol.119.117069] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 08/22/2019] [Indexed: 02/06/2023] Open
Abstract
The hepatic endoplasmic reticulum (ER)-anchored monotopic proteins, cytochromes P450 (P450s), are enzymes that metabolize endobiotics (physiologically active steroids and fatty acids), as well as xenobiotics including therapeutic/chemotherapeutic drugs, nutrients, carcinogens, and toxins. Alterations of hepatic P450 content through synthesis, inactivation, or proteolytic turnover influence their metabolic function. P450 proteolytic turnover occurs via ER-associated degradation (ERAD) involving ubiquitin (Ub)-dependent proteasomal degradation (UPD) as a major pathway. UPD critically involves P450 protein ubiquitination by E2/E3 Ub-ligase complexes. We have previously identified the ER-polytopic gp78/AMFR (autocrine motility factor receptor) as a relevant E3 in CYP3A4, CYP3A23, and CYP2E1 UPD. We now document that liver-conditional genetic ablation of gp78/AMFR in male mice disrupts P450 ERAD, resulting in statistically significant stabilization of Cyp2a5 and Cyp2c, in addition to that of Cyp3a and Cyp2e1. More importantly, we establish that such stabilization is of the functionally active P450 proteins, leading to corresponding statistically significant enhancement of their drug-metabolizing capacities. Our findings, with clinically relevant therapeutic drugs (nicotine, coumarin, chlorzoxazone, and acetaminophen) and the prodrug (tamoxifen) as P450 substrates, reveal that P450 ERAD disruption could influence therapeutic drug response and/or toxicity, warranting serious consideration as a potential source of clinically relevant drug-drug interactions (DDIs). Because gp78/AMFR is not only an E3 Ub-ligase, but also a cell-surface prometastatic oncogene that is upregulated in various malignant cancers, our finding that hepatic gp78/AMFR knockout can enhance P450-dependent bioactivation of relevant cancer chemotherapeutic prodrugs is of therapeutic relevance and noteworthy in prospective drug design and development. SIGNIFICANCE STATEMENT: The cell-surface and ER transmembrane protein gp78/AMFR, a receptor for the prometastatic autocrine motility factor (AMF), as well as an E3 ubiquitin-ligase involved in the ER-associated degradation (ERAD) of not only the tumor metastatic suppressor KAI1 but also of hepatic cytochromes P450, is upregulated in various human cancers, enhancing their invasiveness, metastatic potential, and poor prognosis. Liver-specific gp78/AMFR genetic ablation results in functional protein stabilization of several hepatic P450s and consequently enhanced drug and prodrug metabolism, a feature that could be therapeutically exploited in the bioactivation of chemotherapeutic prodrugs through design and development of novel short-term gp78/AMFR chemical inhibitors.
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Affiliation(s)
- Doyoung Kwon
- Departments of Cellular and Molecular Pharmacology (D.K., S.-M.K., Y.L., M.A.C.), Pharmaceutical Chemistry (M.A.C.), and Bioengineering and Therapeutic Sciences (M.A.C.) and The Liver Center (M.A.C.), University of California San Francisco, San Francisco, California; and Clinical Pharmacology Program, Division of Cardiology, Department of Medicine, Center for Tobacco Control Research and Education, University of California, San Francisco, California (P.J.)
| | - Sung-Mi Kim
- Departments of Cellular and Molecular Pharmacology (D.K., S.-M.K., Y.L., M.A.C.), Pharmaceutical Chemistry (M.A.C.), and Bioengineering and Therapeutic Sciences (M.A.C.) and The Liver Center (M.A.C.), University of California San Francisco, San Francisco, California; and Clinical Pharmacology Program, Division of Cardiology, Department of Medicine, Center for Tobacco Control Research and Education, University of California, San Francisco, California (P.J.)
| | - Peyton Jacob
- Departments of Cellular and Molecular Pharmacology (D.K., S.-M.K., Y.L., M.A.C.), Pharmaceutical Chemistry (M.A.C.), and Bioengineering and Therapeutic Sciences (M.A.C.) and The Liver Center (M.A.C.), University of California San Francisco, San Francisco, California; and Clinical Pharmacology Program, Division of Cardiology, Department of Medicine, Center for Tobacco Control Research and Education, University of California, San Francisco, California (P.J.)
| | - Yi Liu
- Departments of Cellular and Molecular Pharmacology (D.K., S.-M.K., Y.L., M.A.C.), Pharmaceutical Chemistry (M.A.C.), and Bioengineering and Therapeutic Sciences (M.A.C.) and The Liver Center (M.A.C.), University of California San Francisco, San Francisco, California; and Clinical Pharmacology Program, Division of Cardiology, Department of Medicine, Center for Tobacco Control Research and Education, University of California, San Francisco, California (P.J.)
| | - Maria Almira Correia
- Departments of Cellular and Molecular Pharmacology (D.K., S.-M.K., Y.L., M.A.C.), Pharmaceutical Chemistry (M.A.C.), and Bioengineering and Therapeutic Sciences (M.A.C.) and The Liver Center (M.A.C.), University of California San Francisco, San Francisco, California; and Clinical Pharmacology Program, Division of Cardiology, Department of Medicine, Center for Tobacco Control Research and Education, University of California, San Francisco, California (P.J.)
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19
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Needham PG, Guerriero CJ, Brodsky JL. Chaperoning Endoplasmic Reticulum-Associated Degradation (ERAD) and Protein Conformational Diseases. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a033928. [PMID: 30670468 DOI: 10.1101/cshperspect.a033928] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Misfolded proteins compromise cellular homeostasis. This is especially problematic in the endoplasmic reticulum (ER), which is a high-capacity protein-folding compartment and whose function requires stringent protein quality-control systems. Multiprotein complexes in the ER are able to identify, remove, ubiquitinate, and deliver misfolded proteins to the 26S proteasome for degradation in the cytosol, and these events are collectively termed ER-associated degradation, or ERAD. Several steps in the ERAD pathway are facilitated by molecular chaperone networks, and the importance of ERAD is highlighted by the fact that this pathway is linked to numerous protein conformational diseases. In this review, we discuss the factors that constitute the ERAD machinery and detail how each step in the pathway occurs. We then highlight the underlying pathophysiology of protein conformational diseases associated with ERAD.
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Affiliation(s)
- Patrick G Needham
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | | | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
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20
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Goder V, Alanis-Dominguez E, Bustamante-Sequeiros M. Lipids and their (un)known effects on ER-associated protein degradation (ERAD). Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158488. [PMID: 31233887 DOI: 10.1016/j.bbalip.2019.06.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/15/2019] [Accepted: 06/18/2019] [Indexed: 02/09/2023]
Abstract
Endoplasmic reticulum (ER)-associated protein degradation (ERAD) is a conserved cellular process that apart from protein quality control and maintenance of ER membrane identity has pivotal functions in regulating the lipid composition of the ER membrane. A general trigger for ERAD activation is the exposure of normally buried protein domains due to protein misfolding, absence of binding partners or conformational changes. Several feedback loops for ER lipid homeostasis exploit the induction of conformational changes in key enzymes of lipid biosynthesis or in ER membrane-embedded transcription factors upon shortage or abundance of specific lipids, leading to enzyme degradation or mobilization of transcription factors. Similarly, an insufficient amount of lipids triggers ERAD of apolipoproteins during lipoprotein formation. Lipids might even have a role in ER protein quality control: when proteins destined for ER export are covalently modified with lipids their ER residence time and their susceptibility to ERAD is reduced. Here we summarize and compare the various interconnections of lipids with ER membrane proteins and ERAD. This article is part of a Special Issue entitled Endoplasmic reticulum platforms for lipid dynamics edited by Shamshad Cockcroft and Christopher Stefan.
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Affiliation(s)
- Veit Goder
- Department of Genetics, University of Seville, 6, Ave Reina Mercedes, 41012 Seville, Spain.
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21
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The ubiquitin specific protease USP34 protects the ubiquitin ligase gp78 from proteasomal degradation. Biochem Biophys Res Commun 2019; 509:348-353. [DOI: 10.1016/j.bbrc.2018.12.141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 12/19/2018] [Indexed: 11/24/2022]
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22
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Mukherjee R, Bhattacharya A, Sau A, Basu S, Chakrabarti S, Chakrabarti O. Calmodulin regulates MGRN1-GP78 interaction mediated ubiquitin proteasomal degradation system. FASEB J 2018; 33:1927-1945. [PMID: 30230921 DOI: 10.1096/fj.201701413rrr] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The mechanism by which the endoplasmic reticulum (ER) ubiquitin ligases sense stress to potentiate their activity is poorly understood. GP78, an ER E3 ligase, is best known for its role in ER-associated protein degradation, although its activity is also linked to mitophagy, ER-mitochondria junctions, and MAPK signaling, thus highlighting the importance of understanding its regulation. In healthy cells, Mahogunin really interesting new gene (RING) finger 1 (MGRN1) interacts with GP78 and proteasomally degrades it to alleviate mitophagy. Here, we identify calmodulin (CaM) as the adapter protein that senses fluctuating cytosolic Ca2+ levels and modulates the Ca2+-dependent MGRN1-GP78 interactions. When stress elevates cytosolic Ca2+ levels in cultured and primary neuronal cells, CaM binds to both E3 ligases and inhibits their interaction. Molecular docking, simulation, and biophysical studies show that CaM interacts with both proteins with different affinities and binding modes. The physiological impact of this interaction switch manifests in the regulation of ER-associated protein degradation, ER-mitochondria junctions, and relative distribution of smooth ER and rough ER.-Mukherjee, R., Bhattacharya, A., Sau, A., Basu, S., Chakrabarti, S., Chakrabarti, O. Calmodulin regulates MGRN1-GP78 interaction mediated ubiquitin proteasomal degradation system.
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Affiliation(s)
- Rukmini Mukherjee
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.,Buchmann Institute for Molecular Life Sciences, Frankfurt Am Main, Germany
| | - Anshu Bhattacharya
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIB-IICB), Kolkata, India
| | - Abhishek Sau
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Samita Basu
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata, India.,Homi Bhabha National Institute, Mumbai, India
| | - Saikat Chakrabarti
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIB-IICB), Kolkata, India
| | - Oishee Chakrabarti
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.,Homi Bhabha National Institute, Mumbai, India
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23
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Doonan LM, Fisher EA, Brodsky JL. Can modulators of apolipoproteinB biogenesis serve as an alternate target for cholesterol-lowering drugs? Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:762-771. [PMID: 29627384 DOI: 10.1016/j.bbalip.2018.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 03/07/2018] [Accepted: 03/27/2018] [Indexed: 12/23/2022]
Abstract
Understanding the molecular defects underlying cardiovascular disease is necessary for the development of therapeutics. The most common method to lower circulating lipids, which reduces the incidence of cardiovascular disease, is statins, but other drugs are now entering the clinic, some of which have been approved. Nevertheless, patients cannot tolerate some of these therapeutics, the drugs are costly, and/or the treatments are approved for only rare forms of disease. Efforts to find alternative treatments have focused on other factors, such as apolipoproteinB (apoB), which transports cholesterol in the blood stream. The levels of apoB are regulated by endoplasmic reticulum (ER) associated degradation as well as by a post ER degradation pathway in model systems, and we suggest that these events provide novel therapeutic targets. We discuss first how cardiovascular disease arises and how cholesterol is regulated, and then summarize the mechanisms of action of existing treatments for cardiovascular disease. We then review the apoB biosynthetic pathway, focusing on steps that might be amenable to therapeutic interventions.
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Affiliation(s)
- Lynley M Doonan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Edward A Fisher
- Departments of Medicine (Cardiology) and Cell Biology and the Marc and Ruti Bell Program in Vascular Biology, New York University School of Medicine, New York, NY 10016, United States
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States.
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24
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Joshi V, Upadhyay A, Kumar A, Mishra A. Gp78 E3 Ubiquitin Ligase: Essential Functions and Contributions in Proteostasis. Front Cell Neurosci 2017; 11:259. [PMID: 28890687 PMCID: PMC5575403 DOI: 10.3389/fncel.2017.00259] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/09/2017] [Indexed: 11/26/2022] Open
Abstract
As per the requirement of metabolism and fitness, normal cellular functions are controlled by several proteins, and their interactive molecular and signaling events at multiple levels. Protein quality control (PQC) mechanisms ensure the correct folding and proper utilization of these proteins to avoid their misfolding and aggregation. To maintain the optimum environment of complex proteome PQC system employs various E3 ubiquitin ligases for the selective degradation of aberrant proteins. Glycoprotein 78 (Gp78) is an E3 ubiquitin ligase that prevents multifactorial deleterious accumulation of different misfolded proteins via endoplasmic reticulum-associated degradation (ERAD). However, the precise role of Gp78 under stress conditions to avoid bulk misfolded aggregation is unclear, which can act as a crucial resource to establish the dynamic nature of the proteome. Present article systematically explains the detailed molecular characterization of Gp78 and also addresses its various cellular physiological functions, which could be crucial to achieving protein homeostasis. Here, we comprehensively represent the current findings of Gp78, which shows its PQC roles in different physiological functions and diseases; and thereby propose novel opportunities to better understand the unsolved questions for therapeutic interventions linked with different protein misfolding disorders.
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Affiliation(s)
- Vibhuti Joshi
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology JodhpurJodhpur, India
| | - Arun Upadhyay
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology JodhpurJodhpur, India
| | - Amit Kumar
- Centre for Biosciences and Biomedical Engineering, Indian Institute of Technology IndoreIndore, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology JodhpurJodhpur, India
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25
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Engle SM, Crowder JJ, Watts SG, Indovina CJ, Coffey SZ, Rubenstein EM. Acetylation of N-terminus and two internal amino acids is dispensable for degradation of a protein that aberrantly engages the endoplasmic reticulum translocon. PeerJ 2017; 5:e3728. [PMID: 28848693 PMCID: PMC5571791 DOI: 10.7717/peerj.3728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/02/2017] [Indexed: 12/26/2022] Open
Abstract
Conserved homologues of the Hrd1 ubiquitin ligase target for degradation proteins that persistently or aberrantly engage the endoplasmic reticulum translocon, including mammalian apolipoprotein B (apoB; the major protein component of low-density lipoproteins) and the artificial yeast protein Deg1-Sec62. A complete understanding of the molecular mechanism by which translocon-associated proteins are recognized and degraded may inform the development of therapeutic strategies for cholesterol-related pathologies. Both apoB and Deg1-Sec62 are extensively post-translationally modified. Mass spectrometry of a variant of Deg1-Sec62 revealed that the protein is acetylated at the N-terminal methionine and two internal lysine residues. N-terminal and internal acetylation regulates the degradation of a variety of unstable proteins. However, preventing N-terminal and internal acetylation had no detectable consequence for Hrd1-mediated proteolysis of Deg1-Sec62. Our data highlight the importance of empirically validating the role of post-translational modifications and sequence motifs on protein degradation, even when such elements have previously been demonstrated sufficient to destine other proteins for destruction.
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Affiliation(s)
- Sarah M Engle
- Department of Biology, Ball State University, Muncie, IN, United States of America.,Immunology-Translational Science, Eli Lilly and Company, Indianapolis, IN, United States of America
| | - Justin J Crowder
- Department of Biology, Ball State University, Muncie, IN, United States of America.,Center for Medical Education, Indiana University School of Medicine, Muncie, IN, United States of America
| | - Sheldon G Watts
- Department of Biology, Ball State University, Muncie, IN, United States of America.,Marian University College of Osteopathic Medicine, Indianapolis, IN, United States of America
| | | | - Samuel Z Coffey
- Department of Biology, Ball State University, Muncie, IN, United States of America.,Medpace Reference Laboratories, Cincinnati, OH, United States of America
| | - Eric M Rubenstein
- Department of Biology, Ball State University, Muncie, IN, United States of America
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26
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Printsev I, Curiel D, Carraway KL. Membrane Protein Quantity Control at the Endoplasmic Reticulum. J Membr Biol 2017; 250:379-392. [PMID: 27743014 PMCID: PMC5392169 DOI: 10.1007/s00232-016-9931-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 09/28/2016] [Indexed: 02/07/2023]
Abstract
The canonical function of the endoplasmic reticulum-associated degradation (ERAD) system is to enforce quality control among membrane-associated proteins by targeting misfolded secreted, intra-organellar, and intramembrane proteins for degradation. However, increasing evidence suggests that ERAD additionally functions in maintaining appropriate levels of a subset of membrane-associated proteins. In this 'quantity control' capacity, ERAD responds to environmental cues to regulate the proteasomal degradation of specific ERAD substrates according to cellular need. In this review, we discuss in detail seven proteins that are targeted by the ERAD quantity control system. Not surprisingly, ERAD-mediated protein degradation is a key regulatory feature of a variety of ER-resident proteins, including HMG-CoA reductase, cytochrome P450 3A4, IP3 receptor, and type II iodothyronine deiodinase. In addition, the ERAD quantity control system plays roles in maintaining the proper stoichiometry of multi-protein complexes by mediating the degradation of components that are produced in excess of the limiting subunit. Perhaps somewhat unexpectedly, recent evidence suggests that the ERAD quantity control system also contributes to the regulation of plasma membrane-localized signaling receptors, including the ErbB3 receptor tyrosine kinase and the GABA neurotransmitter receptors. For these substrates, a proportion of the newly synthesized yet properly folded receptors are diverted for degradation at the ER, and are unable to traffic to the plasma membrane. Given that receptor abundance or concentration within the plasma membrane plays key roles in determining signaling efficiency, these observations may point to a novel mechanism for modulating receptor-mediated cellular signaling.
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Affiliation(s)
- Ignat Printsev
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Research Building III, Room 1100B, 4645 2nd Avenue, Sacramento, CA, 95817, USA
| | - Daniel Curiel
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Research Building III, Room 1100B, 4645 2nd Avenue, Sacramento, CA, 95817, USA
| | - Kermit L Carraway
- Department of Biochemistry and Molecular Medicine, and UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Research Building III, Room 1100B, 4645 2nd Avenue, Sacramento, CA, 95817, USA.
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27
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The evolving role of ubiquitin modification in endoplasmic reticulum-associated degradation. Biochem J 2017; 474:445-469. [PMID: 28159894 DOI: 10.1042/bcj20160582] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/12/2016] [Accepted: 12/14/2016] [Indexed: 12/13/2022]
Abstract
The endoplasmic reticulum (ER) serves as a warehouse for factors that augment and control the biogenesis of nascent proteins entering the secretory pathway. In turn, this compartment also harbors the machinery that responds to the presence of misfolded proteins by targeting them for proteolysis via a process known as ER-associated degradation (ERAD). During ERAD, substrates are selected, modified with ubiquitin, removed from the ER, and then degraded by the cytoplasmic 26S proteasome. While integral membrane proteins can directly access the ubiquitination machinery that resides in the cytoplasm or on the cytoplasmic face of the ER membrane, soluble ERAD substrates within the lumen must be retrotranslocated from this compartment. In either case, nearly all ERAD substrates are tagged with a polyubiquitin chain, a modification that represents a commitment step to degrade aberrant proteins. However, increasing evidence indicates that the polyubiquitin chain on ERAD substrates can be further modified, serves to recruit ERAD-requiring factors, and may regulate the ERAD machinery. Amino acid side chains other than lysine on ERAD substrates can also be modified with ubiquitin, and post-translational modifications that affect substrate ubiquitination have been observed. Here, we summarize these data and provide an overview of questions driving this field of research.
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28
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Zhang J, Zamani M, Thiele C, Taher J, Amir Alipour M, Yao Z, Adeli K. AUP1 (Ancient Ubiquitous Protein 1) Is a Key Determinant of Hepatic Very-Low-Density Lipoprotein Assembly and Secretion. Arterioscler Thromb Vasc Biol 2017; 37:633-642. [PMID: 28183703 DOI: 10.1161/atvbaha.117.309000] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 01/23/2017] [Indexed: 12/14/2022]
Abstract
OBJECTIVE AUP1 (ancient ubiquitous protein 1) is an endoplasmic reticulum-associated protein that also localizes to the surface of lipid droplets (LDs), with dual role in protein quality control and LD regulation. Here, we investigated the role of AUP1 in hepatic lipid mobilization and demonstrate critical roles in intracellular biogenesis of apoB100 (apolipoprotein B-100), LD mobilization, and very-low-density lipoprotein (VLDL) assembly and secretion. APPROACH AND RESULTS: siRNA (short/small interfering RNA) knockdown of AUP1 significantly increased secretion of VLDL-sized apoB100-containing particles from HepG2 cells, correcting a key metabolic defect in these cells that normally do not secrete much VLDL. Secreted particles contained higher levels of metabolically labeled triglyceride, and AUP1-deficient cells displayed a larger average size of LDs, suggesting a role for AUP1 in lipid mobilization. Importantly, AUP1 was also found to directly interact with apoB100, and this interaction was enhanced with proteasomal inhibition. Knockdown of AUP1 reduced apoB100 ubiquitination, decreased intracellular degradation of newly synthesized apoB100, and enhanced extracellular apoB100 secretion. Interestingly, the stimulatory effect of AUP1 knockdown on VLDL assembly was reminiscent of the effect previously observed after MEK-ERK (mitogen-activated protein kinase kinase-extracellular signal-regulated kinase) inhibition; however, further studies indicated that the AUP1 effect was independent of MEK-ERK signaling. CONCLUSIONS In summary, our findings reveal an important role for AUP1 as a regulator of apoB100 stability, hepatic LD metabolism, and intracellular lipidation of VLDL particles. AUP1 may be a crucial factor in apoB100 quality control, determining the rate at which apoB100 is degraded or lipidated to enable VLDL particle assembly and secretion.
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Affiliation(s)
- Jing Zhang
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Mostafa Zamani
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Christoph Thiele
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Jennifer Taher
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Mohsen Amir Alipour
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Zemin Yao
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Khosrow Adeli
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.).
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29
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Erzurumlu Y, Ballar P. Androgen Mediated Regulation of Endoplasmic Reticulum-Associated Degradation and its Effects on Prostate Cancer. Sci Rep 2017; 7:40719. [PMID: 28091582 PMCID: PMC5238502 DOI: 10.1038/srep40719] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 12/09/2016] [Indexed: 12/12/2022] Open
Abstract
The endoplasmic reticulum (ER) comprises thirty percent of the newly translated proteins in eukaryotic cells. The quality control mechanism within the ER distinguishes between properly and improperly folded proteins and ensures that unwanted proteins are retained in the ER and subsequently degraded through ER-associated degradation (ERAD). Besides cleaning of misfolded proteins ERAD is also important for physiological processes by regulating the abundance of normal proteins of the ER. Thus it is important to unreveal the regulation patterns of ERAD. Here, we describe that ERAD pathway is regulated by androgen, where its inhibitor SVIP was downregulated, all other ERAD genes were upregulated. Consistently, androgen treatment increased the degradation rate of ERAD substrates. Using several independent techniques, we showed that this regulation is through androgen receptor transactivation. ERAD genes found to be upregulated in prostate cancer tissues and silencing expression of Hrd1, SVIP, and gp78 reduced the in vitro migration and malignant transformation of LNCaP cells. Our data suggests that expression levels of ERAD components are regulated by androgens, that promotes ERAD proteolytic activity, which is positively related with prostate tumorigenesis.
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Affiliation(s)
- Yalcin Erzurumlu
- Ege University, Faculty of Pharmacy, Biochemistry Department, Izmir, 35100 Turkey
| | - Petek Ballar
- Ege University, Faculty of Pharmacy, Biochemistry Department, Izmir, 35100 Turkey
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30
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Abstract
The endoplasmic reticulum is the port of entry for proteins into the secretory pathway and the site of synthesis for several important lipids, including cholesterol, triacylglycerol, and phospholipids. Protein production within the endoplasmic reticulum is tightly regulated by a cohort of resident machinery that coordinates the folding, modification, and deployment of secreted and integral membrane proteins. Proteins failing to attain their native conformation are degraded through the endoplasmic reticulum-associated degradation (ERAD) pathway via a series of tightly coupled steps: substrate recognition, dislocation, and ubiquitin-dependent proteasomal destruction. The same ERAD machinery also controls the flux through various metabolic pathways by coupling the turnover of metabolic enzymes to the levels of key metabolites. We review the current understanding and biological significance of ERAD-mediated regulation of lipid metabolism in mammalian cells.
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Affiliation(s)
- Julian Stevenson
- Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720;
| | - Edmond Y Huang
- Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720;
| | - James A Olzmann
- Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720;
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31
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Tiwari S, Siddiqi S, Zhelyabovska O, Siddiqi SA. Silencing of Small Valosin-containing Protein-interacting Protein (SVIP) Reduces Very Low Density Lipoprotein (VLDL) Secretion from Rat Hepatocytes by Disrupting Its Endoplasmic Reticulum (ER)-to-Golgi Trafficking. J Biol Chem 2016; 291:12514-12526. [PMID: 27129256 DOI: 10.1074/jbc.m115.705269] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Indexed: 01/07/2023] Open
Abstract
The transport of nascent very low density lipoprotein (VLDL) particles from the endoplasmic reticulum (ER) to the Golgi determines their secretion by the liver and is mediated by a specialized ER-derived vesicle, the VLDL transport vesicle (VTV). Our previous studies have shown that the formation of ER-derived VTV requires proteins in addition to coat complex II proteins. The VTV proteome revealed that a 9-kDa protein, small valosin-containing protein-interacting protein (SVIP), is uniquely present in these specialized vesicles. Our biochemical and morphological data indicate that the VTV contains SVIP. Using confocal microscopy and co-immunoprecipitation assays, we show that SVIP co-localizes with apolipoprotein B-100 (apoB100) and specifically interacts with VLDL apoB100 and coat complex II proteins. Treatment of ER membranes with myristic acid in the presence of cytosol increases SVIP recruitment to the ER in a concentration-dependent manner. Furthermore, we show that myristic acid treatment of hepatocytes increases both VTV budding and VLDL secretion. To determine the role of SVIP in VTV formation, we either blocked the SVIP protein using specific antibodies or silenced SVIP by siRNA in hepatocytes. Our results show that both blocking and silencing of SVIP lead to significant reduction in VTV formation. Additionally, we show that silencing of SVIP reduces VLDL secretion, suggesting a physiological role of SVIP in intracellular VLDL trafficking and secretion. We conclude that SVIP acts as a novel regulator of VTV formation by interacting with its cargo and coat proteins and has significant implications in VLDL secretion by hepatocytes.
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Affiliation(s)
- Samata Tiwari
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32827
| | - Shaila Siddiqi
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32827
| | - Olga Zhelyabovska
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32827
| | - Shadab A Siddiqi
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32827.
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32
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Mukherjee R, Chakrabarti O. Ubiquitin mediated regulation of the E3 ligase GP78 by Mahogunin in trans affects mitochondrial homeostasis. J Cell Sci 2016; 129:757-73. [DOI: 10.1242/jcs.176537] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 12/29/2015] [Indexed: 12/29/2022] Open
Abstract
Cellular quality control provides an efficient surveillance system to regulate mitochondrial turn-over. This study elucidates a novel interaction of the cytosolic E3 ligase, MGRN1 with the ER ubiquitin E3 ligase, GP78. Loss of Mgrn1 function has been implicated in late-onset spongiform neurodegeneration, congenital heart defects amongst several developmental defects. MGRN1 ubiquitinates GP78 in trans via non-canonical K11 linkages. This helps maintain constitutively low levels of GP78 in healthy cells, in turn downregulating mitophagy. GP78, however, does not regulate MGRN1. When mitochondria are stressed, cytosolic Ca2+ increases.This leads to reduced interaction between MGRN1 and GP78 and its compromised ubiquitination. Chelating Ca2+ restores association between the two ligases and the trans ubiquitination. Catalytic inactivation of MGRN1 results in elevated levels of GP78 and consequential increase in the initiation of mitophagy. This is significant because functional depletion of MGRN1 by membrane-associated disease causing prion protein, CtmPrP affects polyubiquitination and degradation of GP78, also leading to an increase in mitophagy events. This suggests that MGRN1 participates in mitochondrial quality control and could contribute to neurodegeneration in a sub-set of CtmPrP mediated prion diseases.
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Affiliation(s)
- Rukmini Mukherjee
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata – 700064, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata – 700064, India
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33
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Deacetylation of HSPA5 by HDAC6 leads to GP78-mediated HSPA5 ubiquitination at K447 and suppresses metastasis of breast cancer. Oncogene 2015; 35:1517-28. [PMID: 26119938 DOI: 10.1038/onc.2015.214] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 04/09/2015] [Accepted: 04/26/2015] [Indexed: 12/21/2022]
Abstract
Heat-shock protein 5 (HSPA5) is a marker for poor prognosis in breast cancer patients and has an important role in cancer progression, including promoting drug resistance and metastasis. In this study, we identify that the specific lysine residue 447 (K447) of HSPA5 could be modified with polyubiquitin for subsequent degradation through the ubiquitin proteasomal system, leading to the suppression of cell migration and invasion of breast cancer. We further found that GP78, an E3 ubiquitin ligase, interacted with the C-terminal region of HSPA5 and mediated HSPA5 ubiquitination and degradation. Knock down of GP78 significantly increased the expression of HSPA5 and enhanced migration/invasive ability of breast cancer cells. Knock down of histone deacetylase-6 (HDAC6) increased the acetylation of HSPA5 at lysine residues 353 (K353) and reduced GP78-mediated ubiquitination of HSPA5 at K447 and then increased cell migration/invasion. In addition, we demonstrate that E3 ubiquitin ligase GP78 preferentially binds to deacetylated HSPA5. Notably, the expression levels of GP78 inversely correlated with HSPA5 levels in breast cancer patients. Patients with low GP78 expression significantly correlated with invasiveness of breast cancer, advanced tumor stages and poor clinical outcome. Taken together, our results provide new mechanistic insights into the understanding that deacetylation of HSPA5 by HDAC6 facilitates GP78-mediated HSPA5 ubiquitination and suggest that post-translational regulation of HSPA5 protein is critical for HSPA5-mediated metastatic properties of breast cancer.
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34
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Wang Y, Ha SW, Zhang T, Kho DH, Raz A, Xie Y. Polyubiquitylation of AMF requires cooperation between the gp78 and TRIM25 ubiquitin ligases. Oncotarget 2015; 5:2044-51. [PMID: 24810856 PMCID: PMC4039143 DOI: 10.18632/oncotarget.1478] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
gp78 is a ubiquitin ligase that plays a vital role in endoplasmic reticulum (ER)-associated degradation (ERAD). Here we report that autocrine motility factor (AMF), also known as phosphoglucose isomerase (PGI), is a novel substrate of gp78. We show that polyubiquitylation of AMF requires cooperative interaction between gp78 and the ubiquitin ligase TRIM25 (tripartite motif-containing protein 25). While TRIM25 mediates the initial round of ubiquitylation, gp78 catalyzes polyubiquitylation of AMF. The E4-like activity of gp78 was illustrated by an in vitro polyubiquitylation assay using Ub-DHFR as a model substrate. We further demonstrate that TRIM25 ubiquitylates gp78 and that overexpression of TRIM25 accelerates the degradation of gp78. Our data suggest that TRIM25 not only cooperates with gp78 in polyubiquitylation of AMF but also gauges the steady-state level of gp78. This study uncovers a previously unknown functional link between gp78 and TRIM25 and provides mechanistic insight into gp78-mediated protein ubiquitylation.
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Affiliation(s)
- Ying Wang
- Barbara Ann Karmanos Cancer Institute and Department of Oncology, Wayne State University School of Medicine, Detroit, MI, USA
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35
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Huang Z, Zhang N, Zha L, Mao HC, Chen X, Xiang JF, Zhang H, Wang ZW. Aberrant expression of the autocrine motility factor receptor correlates with poor prognosis and promotes metastasis in gastric carcinoma. Asian Pac J Cancer Prev 2014; 15:989-97. [PMID: 24568530 DOI: 10.7314/apjcp.2014.15.2.989] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AMFR, autocrine motility factor receptor, also called gp78, is a cell surface cytokine receptor which has a dual role as an E3 ubiquitin ligase in endoplasmic reticulum-associated degradation. AMFR expression is associated with tumor malignancy. We here investigated the clinical significance of AMFR and its role in metastasis and prognosis in gastric cancer. Expression of AMFR, E-cadherin and N-cadherin in cancer tissues and matched adjacent normal tissues from 122 gastric cancer (GC) patients undergoing surgical resection was assessed by immunohistochemistry. Levels of these molecules in 17 cases selected randomly were also analysed by Western blotting. AMFR expression was significantly increased in gastric cancer tissues, and associated with invasion depth and lymph node metastasis. Kaplan-Meier analysis showed AMFR expression correlated with poor overall survival and an increased risk of recurrence in the GC cases. Cox regression analysis suggested AMFR to be an independent predictor for overall and recurrence-free survival. E-cadherin expression was decreased in gastric cancer tissues; conversely, N-cadherin was increased. Expression of AMFR negatively correlated with E-cadherin expression, whereas N-cadherin expression showed a significant positive correlation with AMFR expression. AMFR might be involved in the regulation of epithelial-mesenchymal transition, with aberrant expression correlating with a poor prognosis and promoting invasion and metastasis in GCs.
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Affiliation(s)
- Zhen Huang
- Department of Gastrointestinal Surgery, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China E-mail :
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36
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Choi K, Kim H, Kang H, Lee SY, Lee SJ, Back SH, Lee SH, Kim MS, Lee JE, Park JY, Kim J, Kim S, Song JH, Choi Y, Lee S, Lee HJ, Kim JH, Cho S. Regulation of diacylglycerol acyltransferase 2 protein stability by gp78-associated endoplasmic-reticulum-associated degradation. FEBS J 2014; 281:3048-60. [DOI: 10.1111/febs.12841] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/28/2014] [Accepted: 05/09/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Kwangman Choi
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Hyeongki Kim
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
- Department of Biomolecular Science; University of Science and Technology; Daejeon Korea
| | - Hyunju Kang
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - So-Young Lee
- International Cooperation Office; Ministry of Food and Drug Safety; Cheongwon Chungbuk Korea
| | - Sang Jun Lee
- Infection and Immunity Research Center; Korea Research Institute of Bioscience and Biotechnology; Daejeon Korea
| | - Sung Hoon Back
- School of Biological Sciences; University of Ulsan; Korea
| | - Seo Hyun Lee
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
| | - M. Sun Kim
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
| | - Jeong Eun Lee
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
| | - Ju Young Park
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
| | - Jiye Kim
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Sunhong Kim
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Jae-Hyung Song
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Yura Choi
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Suui Lee
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Hyun-Jun Lee
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Jong Heon Kim
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
- Department of System Cancer Science; Graduate School of Cancer Science and Policy; National Cancer Center; Goyang Korea
| | - Sungchan Cho
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
- Department of Biomolecular Science; University of Science and Technology; Daejeon Korea
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37
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Abstract
To maintain cholesterol homeostasis, the processes of cholesterol metabolism are regulated at multiple levels including transcription, translation, and enzymatic activity. Recently, the regulation of protein stability of some key players in cholesterol metabolism has been characterized. More and more ubiquitin ligases have been identified including gp78, Hrd1, TRC8, TEB4, Fbw7, and inducible degrader of low density lipoprotein receptor. Their working mechanisms and physiological functions are becoming revealed. Here, we summarize the structure, substrates and function of these ubiquitin ligases. Their potential application in drug discovery is also discussed.
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Affiliation(s)
- Wei Jiang
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Bao-Liang Song
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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38
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Fisher E, Lake E, McLeod RS. Apolipoprotein B100 quality control and the regulation of hepatic very low density lipoprotein secretion. J Biomed Res 2014; 28:178-93. [PMID: 25013401 PMCID: PMC4085555 DOI: 10.7555/jbr.28.20140019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 02/15/2014] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein B (apoB) is the main protein component of very low density lipoprotein (VLDL) and is necessary for the assembly and secretion of these triglyceride (TG)-rich particles. Following release from the liver, VLDL is converted to low density lipoprotein (LDL) in the plasma and increased production of VLDL can therefore play a detrimental role in cardiovascular disease. Increasing evidence has helped to establish VLDL assembly as a target for the treatment of dyslipidemias. Multiple factors are involved in the folding of the apoB protein and the formation of a secretion-competent VLDL particle. Failed VLDL assembly can initiate quality control mechanisms in the hepatocyte that target apoB for degradation. ApoB is a substrate for endoplasmic reticulum associated degradation (ERAD) by the ubiquitin proteasome system and for autophagy. Efficient targeting and disposal of apoB is a regulated process that modulates VLDL secretion and partitioning of TG. Emerging evidence suggests that significant overlap exists between these degradative pathways. For example, the insulin-mediated targeting of apoB to autophagy and postprandial activation of the unfolded protein response (UPR) may employ the same cellular machinery and regulatory cues. Changes in the quality control mechanisms for apoB impact hepatic physiology and pathology states, including insulin resistance and fatty liver. Insulin signaling, lipid metabolism and the hepatic UPR may impact VLDL production, particularly during the postprandial state. In this review we summarize our current understanding of VLDL assembly, apoB degradation, quality control mechanisms and the role of these processes in liver physiology and in pathologic states.
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Affiliation(s)
- Eric Fisher
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Elizabeth Lake
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Roger S McLeod
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
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39
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The effect and mechanism of tamoxifen-induced hepatocyte steatosis in vitro. Int J Mol Sci 2014; 15:4019-30. [PMID: 24603540 PMCID: PMC3975381 DOI: 10.3390/ijms15034019] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 02/11/2014] [Accepted: 02/19/2014] [Indexed: 12/14/2022] Open
Abstract
The aim of this study was to determine the effect and mechanism of tamoxifen (TAM)-induced steatosis in vitro. HepG 2 (Human hepatocellular liver carcinoma cell line) cells were treated with different concentrations of TAM for 72 h. Steatosis of hepatocytes was determined after Oil Red O staining and measurement of triglyceride (TG) concentration. The expressions of genes in the TG homeostasis pathway, including sterol regulatory element-binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), stearoyl-CoA desaturase (SCD), carnitine palmitoyltransferase 1 (CPT1) and microsomal triglyceride transfer protein (MTP), were examined using quantitative real-time PCR and Western blot analysis. Cell proliferation was examined using the cell counting kit-8 (CCK-8) assay. We found that hepatocytes treated with TAM had: (1) induced hepatocyte steatosis and increased hepatocyte TG; (2) upregulation of SREBP-1c, FAS, ACC, SCD and MTP mRNA expressions (300%, 600%, 70%, 130% and 160%, respectively); (3) corresponding upregulation of protein expression; and (4) no difference in HepG 2 cell proliferation. Our results suggest that TAM can induce hepatocyte steatosis in vitro and that the enhancement of fatty acid synthesis through the upregulations of SREBP-1c and its downstream target genes (FAS, ACC and SCD) may be the key mechanism of TAM-induced hepatocyte steatosis.
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40
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Yin J, Zhu JM, Shen XZ. The role and therapeutic implications of RING-finger E3 ubiquitin ligases in hepatocellular carcinoma. Int J Cancer 2014; 136:249-57. [PMID: 24420637 DOI: 10.1002/ijc.28717] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 01/02/2014] [Indexed: 12/30/2022]
Abstract
Increasing evidence indicates that deregulation of RING-finger ubiquitin-protein ligases (E3s) involves in the development of hepatocellular carcinoma (HCC). These RING-finger E3s serve as oncoproteins or tumor suppressors in HCC under specific conditions. In this review, we summarize current knowledge about abnormal RING-finger E3s and their clinical significance in the development of HCC, and discuss parts of critical substrates for these RING-finger E3s in detail. Furthermore, in light of success of Bortezomib in treating hematological malignancies, we describe the preclinical and clinical studies of therapeutic approaches targeting aberrant RING-finger E3s in HCC.
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Affiliation(s)
- Jie Yin
- Department of Gastroenterology, Zhongshan Hospital of Fudan University, Shanghai, China
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41
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Chiu CG, St-Pierre P, Nabi IR, Wiseman SM. Autocrine motility factor receptor: a clinical review. Expert Rev Anticancer Ther 2014; 8:207-17. [DOI: 10.1586/14737140.8.2.207] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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42
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Jacobs JL, Zhu J, Sarkar SN, Coyne CB. Regulation of mitochondrial antiviral signaling (MAVS) expression and signaling by the mitochondria-associated endoplasmic reticulum membrane (MAM) protein Gp78. J Biol Chem 2013; 289:1604-16. [PMID: 24285545 DOI: 10.1074/jbc.m113.520254] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In a previous study, we identified the E3 ubiquitin ligase Gp78 by RNAi high-throughput screening as a gene whose depletion restricted enterovirus infection. In the current study, we show that Gp78, which localizes to the ER-mitochondria interface, is a regulator of RIG-I-like receptor (RLR) antiviral signaling. We show that depletion of Gp78 results in a robust decrease of vesicular stomatitis virus (VSV) infection and a corresponding enhancement of type I interferon (IFN) signaling. Mechanistically, we show that Gp78 modulates type I IFN induction by altering both the expression and signaling of the mitochondria-localized RLR adaptor mitochondrial antiviral signaling (MAVS). Expression of mutants of Gp78 that abolish its E3 ubiquitin ligase and its participation in ER-associated degradation (ERAD) lost their ability to degrade MAVS, but surprisingly maintained their ability to repress RLR signaling. In contrast, Gp78 lacking its entire C terminus lost both its ability to degrade MAVS and repress RLR signaling. We show that Gp78 interacts with both the N- and C-terminal domains of MAVS via its C-terminal RING domain, and that this interaction is required to abrogate Gp78-mediated attenuation of MAVS signaling. Our data thus implicate two parallel pathways by which Gp78 regulates MAVS signaling; one pathway requires its E3 ubiquitin ligase and ERAD activity to directly degrade MAVS, whereas the other pathway occurs independently of these activities, but requires the Gp78 RING domain and occurs via a direct association between this region and MAVS.
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Affiliation(s)
- Jana L Jacobs
- From the Department of Infectious Diseases and Microbiology, Graduate School of Public Health
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43
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Wei HS, Wei HL, Zhao F, Zhong LP, Zhan YT. Glycosyltransferase GLT8D2 positively regulates ApoB100 protein expression in hepatocytes. Int J Mol Sci 2013; 14:21435-46. [PMID: 24173238 PMCID: PMC3856013 DOI: 10.3390/ijms141121435] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/11/2013] [Accepted: 09/12/2013] [Indexed: 12/18/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is characterized by triglyceride (TG) accumulation in hepatocytes. Very low density lipoprotein (VLDL) is a major secretory product of the liver that transports endogenously synthesized TG. Disrupted VLDL secretion may contribute to the accumulation of TG in hepatocytes. ApoB100 (apolipoprotein B100) is a glycoprotein and an essential protein component of VLDL. Its glycosylation may affect VLDL assembly and secretion. However, which glycosyltransferase catalyzes apoB100 glycosylation is unknown. In this study, we cloned the GLT8D2 (glycosyltransferase 8 domain containing 2) gene from HepG2 cells and generated a series of plasmids for in vitro studies of its molecular functions. We discovered that GLT8D2 was localized in the ER, interacted with apoB100, and positively regulated the levels of apoB100 protein in HepG2 cells. Based on these results, we propose that GLT8D2 is a glycosyltransferase of apoB100 that regulates apoB100 levels in hepatocytes.
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Affiliation(s)
- Hong-Shan Wei
- Institutes of Infectious Disease, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China; E-Mail:
| | - Hong-Lian Wei
- Seventh Department of Internal Medicine, Linyi People’s Hospital, Linyi 276000, Shandong, China; E-Mail:
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China; E-Mails: (F.Z.); (L.-P.Z.)
| | - Fei Zhao
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China; E-Mails: (F.Z.); (L.-P.Z.)
| | - Le-Ping Zhong
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China; E-Mails: (F.Z.); (L.-P.Z.)
| | - Yu-Tao Zhan
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China; E-Mails: (F.Z.); (L.-P.Z.)
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44
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Merulla J, Fasana E, Soldà T, Molinari M. Specificity and Regulation of the Endoplasmic Reticulum-Associated Degradation Machinery. Traffic 2013; 14:767-77. [DOI: 10.1111/tra.12068] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/18/2013] [Accepted: 03/23/2013] [Indexed: 02/05/2023]
Affiliation(s)
| | - Elisa Fasana
- Institute for Research in Biomedicine; Protein Folding and Quality Control; CH-6500; Bellinzona; Switzerland
| | - Tatiana Soldà
- Institute for Research in Biomedicine; Protein Folding and Quality Control; CH-6500; Bellinzona; Switzerland
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45
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Fu M, St-Pierre P, Shankar J, Wang PTC, Joshi B, Nabi IR. Regulation of mitophagy by the Gp78 E3 ubiquitin ligase. Mol Biol Cell 2013; 24:1153-62. [PMID: 23427266 PMCID: PMC3623636 DOI: 10.1091/mbc.e12-08-0607] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The Gp78 E3 ubiquitin ligase is shown to target the mitofusin mitochondrial fusion proteins for degradation, inducing mitochondrial fission and mitofusin 1–dependent mitophagy of uncoupled mitochondria. Mitophagy induced by endoplasmic reticulum–associated gp78 defines a distinct cellular pathway to eliminate damaged mitochondria. Glycoprotein 78 (Gp78) is a critical E3 ubiquitin ligase in endoplasmic reticulum–associated degradation. Overexpression of Flag-tagged Gp78 (Flag-gp78), but not Flag-gp78 mutated in its RING-finger domain (Flag-RINGmut) with deficient ubiquitin ligase activity, induces mitochondrial fragmentation and ubiquitination and proteasome-dependent degradation of the mitofusin (Mfn) mitochondrial fusion factors Mfn1/Mfn2. After mitochondrial depolarization with carbonyl cyanide m-chlorophenylhydrazone (CCCP), Flag-gp78 induced a threefold loss of depolarized mitochondria and significant loss of the inner mitochondrial protein OxPhosV. Flag-gp78–dependent loss of OxPhosV, but not Mfn1 or Mfn2, was prevented by small interfering RNA (siRNA) knockdown of the autophagy protein Atg5 in CCCP-treated cells. Gp78-induced mitophagy required ubiquitin ligase activity, as it is not observed upon transfection of Flag-RINGmut or cotransfection of Flag-gp78 with ubiquitin mutated at three critical lysine residues (K29, 48, 63R) involved in polyubiquitin chain elongation. Short hairpin RNA knockdown of Gp78 in HT-1080 fibrosarcoma cells increased mitofusin levels and reduced depolarization-induced mitophagy, whereas siRNA knockdown showed that Mfn1, but not Mfn2, was required for Gp78-dependent depolarization-induced mitophagy. Mitochondrial depolarization induced Gp78-dependent expression of the autophagic marker LC3II and recruitment of enhanced green fluorescent protein–LC3 to the Gp78- and calnexin-labeled, mitochondria-associated ER. Finally, Gp78-induced mitophagy is Parkin independent, as it occurs in Parkin-null HeLa cells and upon siRNA-mediated Parkin knockdown in HEK293 cells. This study therefore describes a novel role for the ER-associated Gp78 ubiquitin ligase and the Mfn1 mitochondrial fusion factor in mitophagy.
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Affiliation(s)
- Min Fu
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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Shankar J, Kojic LD, St-Pierre P, Wang PTC, Fu M, Joshi B, Nabi IR. Raft endocytosis of autocrine motility factor regulates mitochondrial dynamics via rac1 signaling and the gp78 ubiquitin ligase. J Cell Sci 2013; 126:3295-304. [DOI: 10.1242/jcs.120162] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Gp78 is a cell surface receptor that also functions as an E3 ubiquitin ligase in the endoplasmic reticulum-associated degradation (ERAD) pathway. The Gp78 ligand, the glycolytic enzyme phosphoglucose isomerase (also called autocrine motility factor or AMF), functions as a cytokine upon secretion by tumor cells. AMF is internalized via a PI3K- and dynamin-dependent raft endocytic pathway to the smooth endoplasmic reticulum (ER), however the relationship between AMF and Gp78 ubiquitin ligase activity remains unclear. AMF uptake to the smooth ER is inhibited by the dynamin inhibitor, dynasore, reduced in Gp78 knockdown cells and induces the dynamin-dependent downregulation of its cell surface receptor. AMF uptake is Rac1-dependent, inhibited by expression of dominant-negative Rac1 and the Rac1 inhibitor NSC23766, and therefore distinct from Cdc42 and RhoA-dependent raft endocytic pathways. AMF stimulates Rac1 activation, that is reduced by dynasore treatment and absent in Gp78-knockdown cells and therefore requires Gp78-mediated endocytosis. AMF also prevents Gp78-induced degradation of the mitochondrial fusion proteins, Mitofusin 1 and 2 in a dynamin, Rac1 and PI3K-dependent manner. Gp78 induces mitochondrial clustering and fission in a ubiquitin ligase-dependent manner that is also reversed by AMF. The raft-dependent endocytosis of AMF therefore promotes Rac1/PI3K signaling that feeds back to promote AMF endocytosis and also inhibits the ability of Gp78 to target the mitofusins for degradation, thereby preventing Gp78-dependent mitochondrial fission. Through regulation of an ER-localized ubiquitin ligase, the raft-dependent endocytosis of AMF represents an extracellular regulator of mitochondrial fusion and dynamics.
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Rubenstein EM, Kreft SG, Greenblatt W, Swanson R, Hochstrasser M. Aberrant substrate engagement of the ER translocon triggers degradation by the Hrd1 ubiquitin ligase. ACTA ACUST UNITED AC 2012; 197:761-73. [PMID: 22689655 PMCID: PMC3373407 DOI: 10.1083/jcb.201203061] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Hrd1 ubiquitin ligase plays a role in quality control of two substrates associated with the Sec61 translocon. Little is known about quality control of proteins that aberrantly or persistently engage the endoplasmic reticulum (ER)-localized translocon en route to membrane localization or the secretory pathway. Hrd1 and Doa10, the primary ubiquitin ligases that function in ER-associated degradation (ERAD) in yeast, target distinct subsets of misfolded or otherwise abnormal proteins based primarily on degradation signal (degron) location. We report the surprising observation that fusing Deg1, a cytoplasmic degron normally recognized by Doa10, to the Sec62 membrane protein rendered the protein a Hrd1 substrate. Hrd1-dependent degradation occurred when Deg1-Sec62 aberrantly engaged the Sec61 translocon channel and underwent topological rearrangement. Mutations that prevent translocon engagement caused a reversion to Doa10-dependent degradation. Similarly, a variant of apolipoprotein B, a protein known to be cotranslocationally targeted for proteasomal degradation, was also a Hrd1 substrate. Hrd1 therefore likely plays a general role in targeting proteins that persistently associate with and potentially obstruct the translocon.
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Affiliation(s)
- Eric M Rubenstein
- Deptartment of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
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Sparks JD, Sparks CE, Adeli K. Selective hepatic insulin resistance, VLDL overproduction, and hypertriglyceridemia. Arterioscler Thromb Vasc Biol 2012; 32:2104-12. [PMID: 22796579 DOI: 10.1161/atvbaha.111.241463] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Insulin plays a central role in regulating energy metabolism, including hepatic transport of very low-density lipoprotein (VLDL)-associated triglyceride. Hepatic hypersecretion of VLDL and consequent hypertriglyceridemia leads to lower circulating high-density lipoprotein levels and generation of small dense low-density lipoproteins characteristic of the dyslipidemia commonly observed in metabolic syndrome and type 2 diabetes mellitus. Physiological fluctuations of insulin modulate VLDL secretion, and insulin inhibition of VLDL secretion upon feeding may be the first pathway to become resistant in obesity that leads to VLDL hypersecretion. This review summarizes the role of insulin-related signaling pathways that determine hepatic VLDL production. Disruption in signaling pathways that reduce generation of the second messenger phosphatidylinositide (3,4,5) triphosphate downstream of activated phosphatidylinositide 3-kinase underlies the development of VLDL hypersecretion. As insulin resistance progresses, a number of pathways are altered that further augment VLDL hypersecretion, including hepatic inflammatory pathways. Insulin plays a complex role in regulating glucose metabolism, and it is not surprising that the role of insulin in VLDL and lipid metabolism will prove equally complex.
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Affiliation(s)
- Janet D Sparks
- University of Rochester Medical Center, Department of Pathology and Laboratory Medicine, Rochester, NY, USA
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Guerriero CJ, Brodsky JL. The delicate balance between secreted protein folding and endoplasmic reticulum-associated degradation in human physiology. Physiol Rev 2012; 92:537-76. [PMID: 22535891 DOI: 10.1152/physrev.00027.2011] [Citation(s) in RCA: 308] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Protein folding is a complex, error-prone process that often results in an irreparable protein by-product. These by-products can be recognized by cellular quality control machineries and targeted for proteasome-dependent degradation. The folding of proteins in the secretory pathway adds another layer to the protein folding "problem," as the endoplasmic reticulum maintains a unique chemical environment within the cell. In fact, a growing number of diseases are attributed to defects in secretory protein folding, and many of these by-products are targeted for a process known as endoplasmic reticulum-associated degradation (ERAD). Since its discovery, research on the mechanisms underlying the ERAD pathway has provided new insights into how ERAD contributes to human health during both normal and diseases states. Links between ERAD and disease are evidenced from the loss of protein function as a result of degradation, chronic cellular stress when ERAD fails to keep up with misfolded protein production, and the ability of some pathogens to coopt the ERAD pathway. The growing number of ERAD substrates has also illuminated the differences in the machineries used to recognize and degrade a vast array of potential clients for this pathway. Despite all that is known about ERAD, many questions remain, and new paradigms will likely emerge. Clearly, the key to successful disease treatment lies within defining the molecular details of the ERAD pathway and in understanding how this conserved pathway selects and degrades an innumerable cast of substrates.
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Affiliation(s)
- Christopher J Guerriero
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, PA 15260, USA
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Role of the SEL1L:LC3-I complex as an ERAD tuning receptor in the mammalian ER. Mol Cell 2012; 46:809-19. [PMID: 22633958 DOI: 10.1016/j.molcel.2012.04.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 09/01/2011] [Accepted: 04/12/2012] [Indexed: 11/21/2022]
Abstract
Several regulators of endoplasmic reticulum (ER)-associated degradation (ERAD) have a shorter half-life compared to conventional ER chaperones. At steady state, they are selectively removed from the ER by poorly defined events collectively referred to as ERAD tuning. Here we identify the complex comprising the type-I transmembrane protein SEL1L and the cytosolic protein LC3-I as an ERAD tuning receptor regulating the COPII-independent, vesicle-mediated removal of the lumenal ERAD regulators EDEM1 and OS-9 from the ER. Expression of folding-defective polypeptides enhances the lumenal content of EDEM1 and OS-9 by inhibiting their SEL1L:LC3-I-mediated segregation. This raises ERAD activity in the absence of UPR-induction. The mouse hepatitis virus (MHV) subverts ERAD tuning for replication. Consistently, SEL1L or LC3 silencing impair the MHV life cycle. Collectively, our data provide new molecular information about the ERAD tuning mechanisms that regulate ERAD in mammalian cells at the post translational level and how these mechanisms are hijacked by a pathogen.
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