1
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Kim M, Zheng Z. Walking the VLDL tightrope in cardiometabolic diseases. Trends Endocrinol Metab 2024:S1043-2760(24)00201-7. [PMID: 39191606 DOI: 10.1016/j.tem.2024.07.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 07/22/2024] [Accepted: 07/26/2024] [Indexed: 08/29/2024]
Abstract
Very-low-density lipoprotein (VLDL), a triglyceride-rich lipoprotein secreted by hepatocytes, is pivotal for supplying peripheral tissues with fatty acids for energy production. As if walking on a tightrope, perturbations in the balance of VLDL metabolism contribute to cardiometabolic dysfunction, promoting pathologies such as cardiovascular disease (CVD) or metabolic dysfunction-associated steatotic liver disease (MASLD). Despite the advent of lipid-lowering therapies, including statins and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, risks for cardiovascular events persist. With limitations to currently available CVD therapeutics and no US Food and Drug Administration (FDA)-approved treatment for MASLD, this review summarizes the current understanding of VLDL metabolism that sheds light on novel therapeutic avenues to pursue for cardiometabolic disorders.
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Affiliation(s)
- Mindy Kim
- Medical Scientist Training Program, Medical College of Wisconsin, Milwaukee, 53226, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, 53226, USA.
| | - Ze Zheng
- Department of Physiology, Medical College of Wisconsin, Milwaukee, 53226, USA; Department of Medicine, Medical College of Wisconsin, Milwaukee, 53226, USA; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, 53226, USA; Thrombosis & Hemostasis Program, Versiti Blood Research Institute, Milwaukee, 53226, USA.
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2
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Wang Y, Zhou J, Yang Q, Li X, Qiu Y, Zhang Y, Liu M, Zhu AJ. Therapeutic siRNA targeting PLIN2 ameliorates steatosis, inflammation, and fibrosis in steatotic liver disease models. J Lipid Res 2024; 65:100635. [PMID: 39187042 PMCID: PMC11440260 DOI: 10.1016/j.jlr.2024.100635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 07/10/2024] [Accepted: 08/13/2024] [Indexed: 08/28/2024] Open
Abstract
Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent chronic liver disease worldwide. If left untreated, MASLD can progress from simple hepatic steatosis to metabolic dysfunction-associated steatohepatitis, which is characterized by inflammation and fibrosis. Current treatment options for MASLD remain limited, leaving substantial unmet medical needs for innovative therapeutic approaches. Here, we show that PLIN2, a lipid droplet protein inhibiting hepatic lipolysis, serves as a promising therapeutic target for MASLD. Hepatic PLIN2 levels were markedly elevated in multiple MASLD mouse models induced by diverse nutritional and genetic factors. The liver-specific deletion of Plin2 exhibited significant anti-MASLD effects in these models. To translate this discovery into a therapeutic application, we developed a GalNAc-siRNA conjugate with enhanced stabilization chemistry and validated its potent and sustained efficacy in suppressing Plin2 expression in mouse livers. This siRNA therapeutic, named GalNAc-siPlin2, was shown to be biosafe in mice. Treatment with GalNAc-siPlin2 for 6-8 weeks led to a decrease in hepatic triglyceride levels by approximately 60% in high-fat diet- and obesity-induced MASLD mouse models, accompanied with increased hepatic secretion of VLDL-triglyceride and enhanced thermogenesis in brown adipose tissues. Eight-week treatment with GalNAc-siPlin2 significantly improved hepatic steatosis, inflammation, and fibrosis in high-fat/high fructose-induced metabolic dysfunction-associated steatohepatitis models compared to control group. As a proof of concept, we developed a GalNAc-siRNA therapeutic targeting human PLIN2, which effectively suppressed hepatic PLIN2 expression and ameliorated MASLD in humanized PLIN2 knockin mice. Together, our results highlight the potential of GalNAc-siPLIN2 as a candidate MASLD therapeutic for clinical trials.
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Affiliation(s)
- Yao Wang
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China
| | - Jiaxin Zhou
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China
| | - Qi Yang
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China
| | - Xinmeng Li
- Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Yifu Qiu
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China; Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Yansong Zhang
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China; Peking University Chengdu Academy for Advanced Interdisciplinary Biotechnologies, Chengdu, Sichuan, China.
| | - Min Liu
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
| | - Alan Jian Zhu
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China; Peking University Chengdu Academy for Advanced Interdisciplinary Biotechnologies, Chengdu, Sichuan, China.
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3
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Zhang L, Wang X, Chen XW. The biogenesis and transport of triglyceride-rich lipoproteins. Trends Endocrinol Metab 2024:S1043-2760(24)00196-6. [PMID: 39164120 DOI: 10.1016/j.tem.2024.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 07/16/2024] [Accepted: 07/19/2024] [Indexed: 08/22/2024]
Abstract
Triglyceride-rich lipoproteins (TRLs) play essential roles in human health and disease by transporting bulk lipids into the circulation. This review summarizes the fundamental mechanisms and diverse factors governing lipoprotein production, secretion, and regulation. Emphasizing the broader implications for human health, we outline the intricate landscape of lipoprotein research and highlight the potential coordination between the biogenesis and transport of TRLs in physiology, particularly the unexpected coupling of metabolic enzymes and transport machineries. Challenges and opportunities in lipoprotein biology with respect to inherited diseases and viral infections are also discussed. Further characterization of the biogenesis and transport of TRLs will advance both basic research in lipid biology and translational medicine for metabolic diseases.
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Affiliation(s)
- Linqi Zhang
- State Key Laboratory of Membrane Biology, Peking University, Beijing 100871, PR China; Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, PR China
| | - Xiao Wang
- State Key Laboratory of Membrane Biology, Peking University, Beijing 100871, PR China; Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, PR China.
| | - Xiao-Wei Chen
- State Key Laboratory of Membrane Biology, Peking University, Beijing 100871, PR China; Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, PR China; Peking University (PKU)-Tsinghua University (THU) Joint Center for Life Sciences, Peking University, Beijing 100871, PR China.
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4
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Wang B, Li H, Gill G, Zhang X, Tao G, Liu B, Zhai L, Chen W, Wang H, Gu HM, Qin S, Zhang DW. Hepatic Surf4 Deficiency Impairs Serum Amyloid A1 Secretion and Attenuates Liver Fibrosis in Mice. RESEARCH (WASHINGTON, D.C.) 2024; 7:0435. [PMID: 39105051 PMCID: PMC11298252 DOI: 10.34133/research.0435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 07/02/2024] [Indexed: 08/07/2024]
Abstract
Liver fibrosis is a severe global health problem. However, no effective antifibrotic drugs have been approved. Surf4 is primarily located in the endoplasmic reticulum (ER) and mediates the transport of secreted proteins from the ER to the Golgi apparatus. Knockout of hepatic Surf4 (Surf4 LKO) in mice impairs very-low-density lipoprotein secretion without causing overt liver damage. Here, we found that collagen levels are significantly reduced in the liver of Surf4 LKO mice compared with control Surf4 flox mice, as demonstrated by proteomics, Western blot, and quantitative reverse transcription polymerase chain reaction. Therefore, this study aims to investigate whether and how hepatic Surf4 affects liver fibrosis. We observed that CCl4-induced liver fibrosis is significantly lower in Surf4 LKO mice than in Surf4 flox mice. Mechanistically, hepatic Surf4 deficiency reduces serum amyloid A1 (SAA1) secretion and hepatic stellate cell (HSC) activation. Surf4 coimmunoprecipitates and colocalizes with SAA1. Lack of hepatic Surf4 significantly reduces SAA1 secretion from hepatocytes, and SAA1 activates cultured human HSCs (LX-2 cells). Conditioned medium (CM) from Surf4-deficient primary hepatocytes activates LX-2 cells to a much lesser extent than CM from Surf4 flox primary hepatocytes, and this reduced effect is restored by the addition of recombinant SAA1 to CM from Surf4-deficient hepatocytes. Knockdown of SAA1 in primary hepatocytes or TLR2 in LX-2 cells significantly reduces LX-2 activation induced by CM from Surf4 flox hepatocytes but not from Surf4 LKO hepatocytes. Furthermore, knockdown of SAA1 significantly ameliorates liver fibrosis in Surf4 flox mice but does not further reduce liver fibrosis in Surf4 LKO mice. We also observe substantial expression of Surf4 and SAA1 in human fibrotic livers. Therefore, hepatic Surf4 facilitates SAA1 secretion, activates HSCs, and aggravates liver fibrosis, suggesting that hepatic Surf4 and SAA1 may serve as treatment targets for liver fibrosis.
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Affiliation(s)
- Bingxiang Wang
- School of Clinic and Basic Medical Sciences, The Second Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan,China
- Institute of Atherosclerosis in Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Huili Li
- School of Clinic and Basic Medical Sciences, The Second Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan,China
- Institute of Atherosclerosis in Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Govind Gill
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Xiangyan Zhang
- Department of Pathology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Geru Tao
- School of Clinic and Basic Medical Sciences, The Second Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan,China
- Institute of Atherosclerosis in Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Boyan Liu
- School of Clinic and Basic Medical Sciences, The Second Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan,China
- Institute of Atherosclerosis in Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Lei Zhai
- School of Clinic and Basic Medical Sciences, The Second Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan,China
- Institute of Atherosclerosis in Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Wei Chen
- School of Clinic and Basic Medical Sciences, The Second Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan,China
- Institute of Atherosclerosis in Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Hao Wang
- School of Clinic and Basic Medical Sciences, The Second Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan,China
- Institute of Atherosclerosis in Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Hong-mei Gu
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Shucun Qin
- School of Clinic and Basic Medical Sciences, The Second Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan,China
- Institute of Atherosclerosis in Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Da-wei Zhang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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5
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Borén J, Taskinen MR, Packard CJ. Biosynthesis and Metabolism of ApoB-Containing Lipoproteins. Annu Rev Nutr 2024; 44:179-204. [PMID: 38635875 DOI: 10.1146/annurev-nutr-062222-020716] [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] [Indexed: 04/20/2024]
Abstract
Recent advances in human genetics, together with a substantial body of epidemiological, preclinical and clinical trial evidence, strongly support a causal relationship between triglyceride-rich lipoproteins (TRLs) and atherosclerotic cardiovascular disease. Consequently, the secretion and metabolism of TRLs have a significant impact on cardiovascular health. This knowledge underscores the importance of understanding the molecular mechanisms and regulation of very-low-density lipoprotein (VLDL) and chylomicron biogenesis. Fortunately, there has been a resurgence of interest in the intracellular assembly, trafficking, degradation, and secretion of VLDL, leading to many ground-breaking molecular insights. Furthermore, the identification of molecular control mechanisms related to triglyceride metabolism has greatly advanced our understanding of the complex metabolism of TRLs. In this review, we explore recent advances in the assembly, secretion, and metabolism of TRLs. We also discuss available treatment strategies for hypertriglyceridemia.
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Affiliation(s)
- Jan Borén
- Wallenberg Laboratory, Sahlgrenska University Hospital, Gothenburg, Sweden
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden;
| | - Marja-Riitta Taskinen
- Research Programs Unit, Clinical and Molecular Metabolism, University of Helsinki, Helsinki, Finland
| | - Chris J Packard
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
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6
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Tang VT, Xiang J, Chen Z, McCormick J, Abbineni PS, Chen XW, Hoenerhoff M, Emmer BT, Khoriaty R, Lin JD, Ginsburg D. Functional overlap between the mammalian Sar1a and Sar1b paralogs in vivo. Proc Natl Acad Sci U S A 2024; 121:e2322164121. [PMID: 38687799 PMCID: PMC11087783 DOI: 10.1073/pnas.2322164121] [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: 12/20/2023] [Accepted: 03/29/2024] [Indexed: 05/02/2024] Open
Abstract
Proteins carrying a signal peptide and/or a transmembrane domain enter the intracellular secretory pathway at the endoplasmic reticulum (ER) and are transported to the Golgi apparatus via COPII vesicles or tubules. SAR1 initiates COPII coat assembly by recruiting other coat proteins to the ER membrane. Mammalian genomes encode two SAR1 paralogs, SAR1A and SAR1B. While these paralogs exhibit ~90% amino acid sequence identity, it is unknown whether they perform distinct or overlapping functions in vivo. We now report that genetic inactivation of Sar1a in mice results in lethality during midembryogenesis. We also confirm previous reports that complete deficiency of murine Sar1b results in perinatal lethality. In contrast, we demonstrate that deletion of Sar1b restricted to hepatocytes is compatible with survival, though resulting in hypocholesterolemia that can be rescued by adenovirus-mediated overexpression of either SAR1A or SAR1B. To further examine the in vivo function of these two paralogs, we genetically engineered mice with the Sar1a coding sequence replacing that of Sar1b at the endogenous Sar1b locus. Mice homozygous for this allele survive to adulthood and are phenotypically normal, demonstrating complete or near-complete overlap in function between the two SAR1 protein paralogs in mice. These data also suggest upregulation of SAR1A gene expression as a potential approach for the treatment of SAR1B deficiency (chylomicron retention disease) in humans.
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Affiliation(s)
- Vi T. Tang
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI48109
- Life Sciences Institute, University of Michigan, Ann Arbor, MI48109
| | - Jie Xiang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI48109
| | - Zhimin Chen
- Life Sciences Institute, University of Michigan, Ann Arbor, MI48109
| | - Joseph McCormick
- Life Sciences Institute, University of Michigan, Ann Arbor, MI48109
| | - Prabhodh S. Abbineni
- Life Sciences Institute, University of Michigan, Ann Arbor, MI48109
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, IL60153
| | - Xiao-Wei Chen
- State Key Laboratory of Membrane Biology, Peking University, Beijing100871, China
| | - Mark Hoenerhoff
- Unit for Laboratory Animal Medicine, University of Michigan, Ann Arbor, MI48109
| | - Brian T. Emmer
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI48109
| | - Rami Khoriaty
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI48109
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI48109
| | - Jiandie D. Lin
- Department of Human Genetics, University of Michigan, Ann Arbor, MI48109
| | - David Ginsburg
- Life Sciences Institute, University of Michigan, Ann Arbor, MI48109
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI48109
- Department of Human Genetics, University of Michigan, Ann Arbor, MI48109
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI48109
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7
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Xu L, Li L, Wu L, Li P, Chen FJ. CIDE proteins and their regulatory mechanisms in lipid droplet fusion and growth. FEBS Lett 2024; 598:1154-1169. [PMID: 38355218 DOI: 10.1002/1873-3468.14823] [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: 10/28/2023] [Revised: 12/19/2023] [Accepted: 01/04/2024] [Indexed: 02/16/2024]
Abstract
The cell death-inducing DFF45-like effector (CIDE) proteins, including Cidea, Cideb, and Cidec/Fsp27, regulate various aspects of lipid homeostasis, including lipid storage, lipolysis, and lipid secretion. This review focuses on the physiological roles of CIDE proteins based on studies on knockout mouse models and human patients bearing CIDE mutations. The primary cellular function of CIDE proteins is to localize to lipid droplets (LDs) and to control LD fusion and growth across different cell types. We propose a four-step process of LD fusion, characterized by (a) the recruitment of CIDE proteins to the LD surface and CIDE movement, (b) the enrichment and condensate formation of CIDE proteins to form LD fusion plates at LD-LD contact sites, (c) lipid transfer through lipid-permeable passageways within the fusion plates, and (d) the completion of LD fusion. Lastly, we outline CIDE-interacting proteins as regulatory factors, as well as their contribution in LD fusion.
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Affiliation(s)
- Li Xu
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lizhen Li
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lingzhi Wu
- College of Future Technology, Peking University, Beijing, China
| | - Peng Li
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China
- Tianjian Laboratory of Advanced Biomedical Sciences, Zhengzhou University, China
| | - Feng-Jung Chen
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China
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8
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Hu W, Kong X, Cui Y, Wang H, Gao J, Wang X, Chen S, Li X, Li S, Che F, Wan Q. Surfeit Locus Protein 4 as a Novel Target for Therapeutic Intervention in Cerebral Ischemia-Reperfusion Injury. Mol Neurobiol 2024; 61:2033-2048. [PMID: 37843800 DOI: 10.1007/s12035-023-03687-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 10/01/2023] [Indexed: 10/17/2023]
Abstract
Surfeit locus protein 4 (SURF4) functions as a cargo receptor that is capable of transporting newly formed proteins from the lumen of the endoplasmic reticulum into vesicles and Golgi bodies. However, the role of SURF4 in the central nervous system remains unclear. The aim of this study is to investigate the role of SURF4 and its underlying mechanisms in cerebral ischemia/reperfusion (I/R) injury in rats, and whether it can be used effectively for novel therapeutic intervention. We also examined whether transcranial direct-current stimulation (tDCS) can exert a neuroprotective effect via SURF4-dependent signalling. Following cerebral I/R injury in rats, a significant increase was observed in the expression of SURF4. In both I/R injury and oxygen-glucose deprivation (OGD) insult, suppressing the expression of SURF4 demonstrated a neuroprotective effect, while overexpression of SURF4 resulted in increased neuronal death. We further showed that the levels of nerve growth factor precursor (proNGF), p75 neurotrophin receptor (p75NTR), sortilin, and PTEN were increased following cerebral I/R injury, and that SURF4 acted through the PTEN/proNGF signal pathway to regulate neuronal viability. We demonstrated that tDCS treatment reduced SURF4 expression and decreased the infarct volume after cerebral I/R injury. Together, this study indicates that SURF4 plays a critical role in ischemic neuronal injury and may serve as a molecular target for the development of therapeutic strategies in acute ischemic stroke.
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Affiliation(s)
- Wenjie Hu
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
- Department of Biological Science, Jining Medical University, Rizhao, China
| | - Xiangyi Kong
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
| | - Yu Cui
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
| | - Hui Wang
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
| | - Jingchen Gao
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
| | - Xiyuran Wang
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
| | - Shujun Chen
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
| | - Xiaohua Li
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
| | - Shifang Li
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China
| | - Fengyuan Che
- Central Laboratory, Department of Neurology, Linyi People's Hospital, 27 East Jiefang Road, Linyi, China.
| | - Qi Wan
- Institute of Neuroregeneration & Neurorehabilitation, Department of Neurosurgery, School of Basic Medicine, Qingdao University, 308 Ningxia Street, Qingdao, China.
- Qingdao Gui-Hong Intelligent Medical Technology Co. Ltd, Qingdao High-tech Industrial Development District, 7 Fenglong Road, Qingdao, China.
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9
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Thierer JH, Foresti O, Yadav PK, Wilson MH, Moll TOC, Shen MC, Busch-Nentwich EM, Morash M, Mohlke KL, Rawls JF, Malhotra V, Hussain MM, Farber SA. Pla2g12b drives expansion of triglyceride-rich lipoproteins. Nat Commun 2024; 15:2095. [PMID: 38453914 PMCID: PMC10920679 DOI: 10.1038/s41467-024-46102-4] [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: 03/09/2023] [Accepted: 02/14/2024] [Indexed: 03/09/2024] Open
Abstract
Vertebrates transport hydrophobic triglycerides through the circulatory system by packaging them within amphipathic particles called Triglyceride-Rich Lipoproteins. Yet, it remains largely unknown how triglycerides are loaded onto these particles. Mutations in Phospholipase A2 group 12B (PLA2G12B) are known to disrupt lipoprotein homeostasis, but its mechanistic role in this process remains unclear. Here we report that PLA2G12B channels lipids within the lumen of the endoplasmic reticulum into nascent lipoproteins. This activity promotes efficient lipid secretion while preventing excess accumulation of intracellular lipids. We characterize the functional domains, subcellular localization, and interacting partners of PLA2G12B, demonstrating that PLA2G12B is calcium-dependent and tightly associated with the membrane of the endoplasmic reticulum. We also detect profound resistance to atherosclerosis in PLA2G12B mutant mice, suggesting an evolutionary tradeoff between triglyceride transport and cardiovascular disease risk. Here we identify PLA2G12B as a key driver of triglyceride incorporation into vertebrate lipoproteins.
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Affiliation(s)
- James H Thierer
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
- Johns Hopkins University in Baltimore, Maryland Department of biology, Baltimore, MD, 21218, USA
| | - Ombretta Foresti
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, 08003, ES, Spain
| | - Pradeep Kumar Yadav
- Department of Foundations of Medicine, NYU Long Island School of Medicine, Mineola, NY, 11501, USA
- Department of Botany, Faculty of Science, University of Allahabad, Prayagraj, India
| | - Meredith H Wilson
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
- Johns Hopkins University in Baltimore, Maryland Department of biology, Baltimore, MD, 21218, USA
| | - Tabea O C Moll
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
- Johns Hopkins University in Baltimore, Maryland Department of biology, Baltimore, MD, 21218, USA
| | - Meng-Chieh Shen
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
| | | | - Margaret Morash
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, 27708, USA
| | - Karen L Mohlke
- Department of Genetics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - John F Rawls
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, 27708, USA
| | - Vivek Malhotra
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, 08003, ES, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | - M Mahmood Hussain
- Department of Foundations of Medicine, NYU Long Island School of Medicine, Mineola, NY, 11501, USA
| | - Steven A Farber
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA.
- Johns Hopkins University in Baltimore, Maryland Department of biology, Baltimore, MD, 21218, USA.
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10
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Tang VT, Xiang J, Chen Z, McCormick J, Abbineni PS, Chen XW, Hoenerhoff M, Emmer BT, Khoriaty R, Lin JD, Ginsburg D. Functional overlap between the mammalian Sar1a and Sar1b paralogs in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.27.582310. [PMID: 38463989 PMCID: PMC10925261 DOI: 10.1101/2024.02.27.582310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Proteins carrying a signal peptide and/or a transmembrane domain enter the intracellular secretory pathway at the endoplasmic reticulum (ER) and are transported to the Golgi apparatus via COPII vesicles or tubules. SAR1 initiates COPII coat assembly by recruiting other coat proteins to the ER membrane. Mammalian genomes encode two SAR1 paralogs, SAR1A and SAR1B. While these paralogs exhibit ~90% amino acid sequence identity, it is unknown whether they perform distinct or overlapping functions in vivo. We now report that genetic inactivation of Sar1a in mice results in lethality during mid-embryogenesis. We also confirm previous reports that complete deficiency of murine Sar1b results in perinatal lethality. In contrast, we demonstrate that deletion of Sar1b restricted to hepatocytes is compatible with survival, though resulting in hypocholesterolemia that can be rescued by adenovirus-mediated overexpression of either SAR1A or SAR1B. To further examine the in vivo function of these 2 paralogs, we genetically engineered mice with the Sar1a coding sequence replacing that of Sar1b at the endogenous Sar1b locus. Mice homozygous for this allele survive to adulthood and are phenotypically normal, demonstrating complete or near-complete overlap in function between the two SAR1 protein paralogs in mice. These data also suggest upregulation of SAR1A gene expression as a potential approach for the treatment of SAR1B deficiency (chylomicron retention disease) in humans.
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Affiliation(s)
- Vi T. Tang
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Jie Xiang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Zhimin Chen
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Joseph McCormick
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Prabhodh S. Abbineni
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153
| | - Xiao-Wei Chen
- State Key Laboratory of Membrane Biology, Peking University, Beijing 100871, China
| | - Mark Hoenerhoff
- Unit for Laboratory Animal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Brian T. Emmer
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Rami Khoriaty
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Jiandie D. Lin
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
| | - David Ginsburg
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI 48109
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11
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Li D, Zhou X, Xu W, Cai Y, Mu C, Zhao X, Tang T, Liang C, Yang T, Zheng J, Wei L, Ma B. High-fat diet promotes prostate cancer metastasis via RPS27. Cancer Metab 2024; 12:6. [PMID: 38365771 PMCID: PMC10870677 DOI: 10.1186/s40170-024-00333-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 02/06/2024] [Indexed: 02/18/2024] Open
Abstract
BACKGROUND Metastasis is the leading cause of death among prostate cancer (PCa) patients. Obesity is associated with both PCa-specific and all-cause mortality. High-fat diet (HFD) is a risk factor contributing to obesity. However, the association of HFD with PCa metastasis and its underlying mechanisms are unclear. METHODS Tumor xenografts were conducted by intrasplenic injections. The ability of migration or invasion was detected by transwell assay. The expression levels of RPS27 were detected by QRT-PCR and western blot. RESULTS The present study verified the increase in PCa metastasis caused by HFD in mice. Bioinformatics analysis demonstrated increased RPS27 in the experimentally induced PCa in HFD mice, indicating that it is an unfavorable prognostic factor. Intrasplenic injections were used to demonstrate that RPS27 overexpression promotes, while RPS27 knockdown significantly reduces, PCa liver metastasis. Moreover, RPS27 inhibition suppresses the effects of HFD on PCa metastasis. Further mRNA sequencing analysis revealed that RPS27 promotes PCa metastasis by selectively enhancing the expression of various genes. CONCLUSION Our findings indicate that HFD increases the risk of PCa metastasis by elevating RPS27 expression and, subsequently, the expression of genes involved in PRAD progression. Therefore, RPS27 may serve as a novel target for the diagnosis and treatment of metastatic PCa.
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Affiliation(s)
- Dameng Li
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Xueying Zhou
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Wenxian Xu
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Yongxin Cai
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Chenglong Mu
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Xinchun Zhao
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Tingting Tang
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Chen Liang
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Tao Yang
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Junnian Zheng
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China.
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
| | - Liang Wei
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China.
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
| | - Bo Ma
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221002, Jiangsu, China.
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
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12
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Chen Z, Wang S, Pottekat A, Duffey A, Jang I, Chang BH, Cho J, Finck BN, Davidson NO, Kaufman RJ. Conditional hepatocyte ablation of PDIA1 uncovers indispensable roles in both APOB and MTTP folding to support VLDL secretion. Mol Metab 2024; 80:101874. [PMID: 38211723 PMCID: PMC10832468 DOI: 10.1016/j.molmet.2024.101874] [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: 12/08/2023] [Revised: 01/04/2024] [Accepted: 01/06/2024] [Indexed: 01/13/2024] Open
Abstract
OBJECTIVES The assembly and secretion of hepatic very low-density lipoprotein (VLDL) plays pivotal roles in hepatic and plasma lipid homeostasis. Protein disulfide isomerase A1 (PDIA1/P4HB) is a molecular chaperone whose functions are essential for protein folding in the endoplasmic reticulum. Here we investigated the physiological requirement in vivo for PDIA1 in maintaining VLDL assembly and secretion. METHODS Pdia1/P4hb was conditionally deleted in adult mouse hepatocytes and the phenotypes characterized. Mechanistic analyses in primary hepatocytes determined how PDIA1 ablation alters MTTP synthesis and degradation as well as altering synthesis and secretion of Apolipoprotein B (APOB), along with complementary expression of intact PDIA1 vs a catalytically inactivated PDIA1 mutant. RESULTS Hepatocyte-specific deletion of Pdia1/P4hb inhibited hepatic MTTP expression and dramatically reduced VLDL production, leading to severe hepatic steatosis and hypolipidemia. Pdia1-deletion did not affect mRNA expression or protein stability of MTTP but rather prevented Mttp mRNA translation. We demonstrate an essential role for PDIA1 in MTTP synthesis and function and show that PDIA1 interacts with APOB in an MTTP-independent manner via its molecular chaperone function to support APOB folding and secretion. CONCLUSIONS PDIA1 plays indispensable roles in APOB folding, MTTP synthesis and activity to support VLDL assembly. Thus, like APOB and MTTP, PDIA1 is an obligatory component of hepatic VLDL production.
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Affiliation(s)
- Zhouji Chen
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA.
| | - Shiyu Wang
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA
| | - Anita Pottekat
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA
| | - Alec Duffey
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA
| | - Insook Jang
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA
| | - Benny H Chang
- Section of Nephrology, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jaehyung Cho
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Brian N Finck
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nicholas O Davidson
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Randal J Kaufman
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA.
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13
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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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14
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Singin Ö, Astapenka A, Costina V, Kühl S, Bonekamp N, Drews O, Islinger M. Analysis of the Mouse Hepatic Peroxisome Proteome-Identification of Novel Protein Constituents Using a Semi-Quantitative SWATH-MS Approach. Cells 2024; 13:176. [PMID: 38247867 PMCID: PMC10814758 DOI: 10.3390/cells13020176] [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: 12/21/2023] [Revised: 01/12/2024] [Accepted: 01/15/2024] [Indexed: 01/23/2024] Open
Abstract
Ongoing technical and bioinformatics improvements in mass spectrometry (MS) allow for the identifying and quantifying of the enrichment of increasingly less-abundant proteins in individual fractions. Accordingly, this study reassessed the proteome of mouse liver peroxisomes by the parallel isolation of peroxisomes from a mitochondria- and a microsome-enriched prefraction, combining density-gradient centrifugation with a semi-quantitative SWATH-MS proteomics approach to unveil novel peroxisomal or peroxisome-associated proteins. In total, 1071 proteins were identified using MS and assessed in terms of their distribution in either high-density peroxisomal or low-density gradient fractions, containing the bulk of organelle material. Combining the data from both fractionation approaches allowed for the identification of specific protein profiles characteristic of mitochondria, the ER and peroxisomes. Among the proteins significantly enriched in the peroxisomal cluster were several novel peroxisomal candidates. Five of those were validated by colocalization in peroxisomes, using confocal microscopy. The peroxisomal import of HTATIP2 and PAFAH2, which contain a peroxisome-targeting sequence 1 (PTS1), could be confirmed by overexpression in HepG2 cells. The candidates SAR1B and PDCD6, which are known ER-exit-site proteins, did not directly colocalize with peroxisomes, but resided at ER sites, which frequently surrounded peroxisomes. Hence, both proteins might concentrate at presumably co-purified peroxisome-ER membrane contacts. Intriguingly, the fifth candidate, OCIA domain-containing protein 1, was previously described as decreasing mitochondrial network formation. In this work, we confirmed its peroxisomal localization and further observed a reduction in peroxisome numbers in response to OCIAD1 overexpression. Hence, OCIAD1 appears to be a novel protein, which has an impact on both mitochondrial and peroxisomal maintenance.
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Affiliation(s)
- Öznur Singin
- Neuroanatomy, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, D-68167 Mannheim, Germany; (Ö.S.); (A.A.); (S.K.); (N.B.)
| | - Artur Astapenka
- Neuroanatomy, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, D-68167 Mannheim, Germany; (Ö.S.); (A.A.); (S.K.); (N.B.)
| | - Victor Costina
- Institute of Clinical Chemistry, Medical Faculty Mannheim, Heidelberg University, D-68167 Mannheim, Germany; (V.C.); (O.D.)
| | - Sandra Kühl
- Neuroanatomy, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, D-68167 Mannheim, Germany; (Ö.S.); (A.A.); (S.K.); (N.B.)
| | - Nina Bonekamp
- Neuroanatomy, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, D-68167 Mannheim, Germany; (Ö.S.); (A.A.); (S.K.); (N.B.)
| | - Oliver Drews
- Institute of Clinical Chemistry, Medical Faculty Mannheim, Heidelberg University, D-68167 Mannheim, Germany; (V.C.); (O.D.)
- Biomedical Mass Spectrometry, Center for Medical Research, Johannes Kepler University Linz, 4020 Linz, Austria
| | - Markus Islinger
- Neuroanatomy, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, D-68167 Mannheim, Germany; (Ö.S.); (A.A.); (S.K.); (N.B.)
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15
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Chen J, Fang Z, Luo Q, Wang X, Warda M, Das A, Oldoni F, Luo F. Unlocking the mysteries of VLDL: exploring its production, intracellular trafficking, and metabolism as therapeutic targets. Lipids Health Dis 2024; 23:14. [PMID: 38216994 PMCID: PMC10785355 DOI: 10.1186/s12944-023-01993-y] [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: 09/04/2023] [Accepted: 12/26/2023] [Indexed: 01/14/2024] Open
Abstract
Reducing circulating lipid levels is the centerpiece of strategies for preventing and treating atherosclerotic cardiovascular disease (ASCVD). Despite many available lipid-lowering medications, a substantial residual cardiovascular risk remains. Current clinical guidelines focus on plasma levels of low-density lipoprotein (LDL). Recent attention has been given to very low-density lipoprotein (VLDL), the precursor to LDL, and its role in the development of coronary atherosclerosis. Preclinical investigations have revealed that interventions targeting VLDL production or promoting VLDL metabolism, independent of the LDL receptor, can potentially decrease cholesterol levels and provide therapeutic benefits. Currently, methods, such as mipomersen, lomitapide, and ANGPTL3 inhibitors, are used to reduce plasma cholesterol and triglyceride levels by regulating the lipidation, secretion, and metabolism of VLDL. Targeting VLDL represents an avenue for new lipid-lowering strategies. Interventions aimed at reducing VLDL production or enhancing VLDL metabolism, independent of the LDL receptor, hold promise for lowering cholesterol levels and providing therapeutic benefits beyond LDL in the management of ASCVD.
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Affiliation(s)
- Jingfei Chen
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, Research Institute of Blood Lipid and Atherosclerosis, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
| | - Zhenfei Fang
- Research Institute of Blood Lipid and Atherosclerosis, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
- Department of Cardiovascular Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
| | - Qin Luo
- Research Institute of Blood Lipid and Atherosclerosis, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
- Department of Cardiovascular Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
| | - Xiao Wang
- State Key Laboratory of Membrane Biology, Peking University, Beijing, 100871, China
| | - Mohamad Warda
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt
- Department of Physiology, Faculty of Veterinary Medicine, Ataturk University, Erzurum, 25240, Turkey
| | - Avash Das
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215-5400, USA
| | - Federico Oldoni
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Fei Luo
- Research Institute of Blood Lipid and Atherosclerosis, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China.
- Department of Cardiovascular Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China.
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16
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Guo CG, Sun R, Wang X, Yuan Y, Xu Y, Li S, Sun X, Wang J, Hu X, Guo T, Chen XW, Xiao RP, Zhang X. Intestinal SURF4 is essential for apolipoprotein transport and lipoprotein secretion. Mol Metab 2024; 79:101847. [PMID: 38042368 PMCID: PMC10755498 DOI: 10.1016/j.molmet.2023.101847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/20/2023] [Accepted: 11/27/2023] [Indexed: 12/04/2023] Open
Abstract
OBJECTIVE Lipoprotein assembly and secretion in the small intestine are critical for dietary fat absorption. Surfeit locus protein 4 (SURF4) serves as a cargo receptor, facilitating the cellular transport of multiple proteins and mediating hepatic lipid secretion in vivo. However, its involvement in intestinal lipid secretion is not fully understood. In this study, we investigated the role of SURF4 in intestinal lipid absorption. METHODS We generated intestine-specific Surf4 knockout mice and characterized the phenotypes. Additionally, we investigated the underlying mechanisms of SURF4 in intestinal lipid secretion using proteomics and cellular models. RESULTS We unveiled that SURF4 is indispensable for apolipoprotein transport and lipoprotein secretion. Intestine-specific Surf4 knockout mice exhibited ectopic lipid deposition in the small intestine and hypolipidemia. Deletion of SURF4 impeded the transport of apolipoprotein A1 (ApoA1), proline-rich acidic protein 1 (PRAP1), and apolipoprotein B48 (ApoB48) and hindered the assembly and secretion of chylomicrons and high-density lipoproteins. CONCLUSIONS SURF4 emerges as a pivotal regulator of intestinal lipid absorption via mediating the secretion of ApoA1, PRAP1 and ApoB48.
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Affiliation(s)
- Chun-Guang Guo
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Rui Sun
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou 310024, China
| | - Xiao Wang
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Ye Yuan
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Yan Xu
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Shihan Li
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Xueting Sun
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Jue Wang
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Xinli Hu
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China
| | - Tiannan Guo
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou 310024, China
| | - Xiao-Wei Chen
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
| | - Rui-Ping Xiao
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
| | - Xiuqin Zhang
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing 100871, China.
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17
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Manganese controls lipoprotein secretion via biomolecular condensation. Nat Cell Biol 2023; 25:1732-1733. [PMID: 37978272 DOI: 10.1038/s41556-023-01300-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
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18
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Tang VT, Abbineni PS, Veiga Leprevost FD, Basrur V, Khoriaty R, Emmer BT, Nesvizhskii AI, Ginsburg D. Identification of LMAN1- and SURF4-Dependent Secretory Cargoes. J Proteome Res 2023; 22:3439-3446. [PMID: 37844105 PMCID: PMC10629478 DOI: 10.1021/acs.jproteome.3c00259] [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: 05/01/2023] [Indexed: 10/18/2023]
Abstract
Most proteins secreted into the extracellular space are first recruited from the endoplasmic reticulum into coat protein complex II (COPII)-coated vesicles or tubules that facilitate their transport to the Golgi apparatus. Although several secreted proteins have been shown to be actively recruited into COPII vesicles and tubules by the cargo receptors LMAN1 and SURF4, the full cargo repertoire of these receptors is unknown. We now report mass spectrometry analysis of conditioned media and cell lysates from HuH7 cells CRISPR targeted to inactivate the LMAN1 or SURF4 gene. We found that LMAN1 has limited clients in HuH7 cells, whereas SURF4 traffics a broad range of cargoes. Analysis of putative SURF4 cargoes suggests that cargo recognition is governed by complex mechanisms rather than interaction with a universal binding motif..
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Affiliation(s)
- Vi T. Tang
- Department
of Molecular and Integrative Physiology and Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Prabhodh S. Abbineni
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Microbiology and Immunology, Loyola University
Chicago Stritch School of Medicine, Maywood, Illinois 60153, United States
| | | | - Venkatesha Basrur
- Department
of Pathology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Rami Khoriaty
- Department
of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Cell and Developmental Biology, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Brian T. Emmer
- Department
of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Alexey I. Nesvizhskii
- Department
of Pathology, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - David Ginsburg
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Human Genetics, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan 48109, United States
- Howard
Hughes Medical Institute, University of
Michigan, Ann Arbor, Michigan 48109, United States
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19
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van Zwol W, Rimbert A, Wolters JC, Smit M, Bloks VW, Kloosterhuis NJ, Huijkman NCA, Koster MH, Tharehalli U, de Neck SM, Bournez C, Fuh MM, Kuipers J, Rajan S, de Bruin A, Ginsberg HN, van Westen GJP, Hussain MM, Scheja L, Heeren J, Zimmerman P, van de Sluis B, Kuivenhoven JA. Loss of hepatic SMLR1 causes hepatosteatosis and protects against atherosclerosis due to decreased hepatic VLDL secretion. Hepatology 2023; 78:1418-1432. [PMID: 36053190 PMCID: PMC10581432 DOI: 10.1002/hep.32709] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 08/02/2022] [Accepted: 08/03/2022] [Indexed: 12/08/2022]
Abstract
BACKGROUND AND AIMS The assembly and secretion of VLDL from the liver, a pathway that affects hepatic and plasma lipids, remains incompletely understood. We set out to identify players in the VLDL biogenesis pathway by identifying genes that are co-expressed with the MTTP gene that encodes for microsomal triglyceride transfer protein, key to the lipidation of apolipoprotein B, the core protein of VLDL. Using human and murine transcriptomic data sets, we identified small leucine-rich protein 1 ( SMLR1 ), encoding for small leucine-rich protein 1, a protein of unknown function that is exclusively expressed in liver and small intestine. APPROACH AND RESULTS To assess the role of SMLR1 in the liver, we used somatic CRISPR/CRISPR-associated protein 9 gene editing to silence murine Smlr1 in hepatocytes ( Smlr1 -LKO). When fed a chow diet, male and female mice show hepatic steatosis, reduced plasma apolipoprotein B and triglycerides, and reduced VLDL secretion without affecting microsomal triglyceride transfer protein activity. Immunofluorescence studies show that SMLR1 is in the endoplasmic reticulum and Cis-Golgi complex. The loss of hepatic SMLR1 in female mice protects against diet-induced hyperlipidemia and atherosclerosis but causes NASH. On a high-fat, high-cholesterol diet, insulin and glucose tolerance tests did not reveal differences in male Smlr1 -LKO mice versus controls. CONCLUSIONS We propose a role for SMLR1 in the trafficking of VLDL from the endoplasmic reticulum to the Cis-Golgi complex. While this study uncovers SMLR1 as a player in the VLDL assembly, trafficking, and secretion pathway, it also shows that NASH can occur with undisturbed glucose homeostasis and atheroprotection.
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Affiliation(s)
- Willemien van Zwol
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Antoine Rimbert
- Université de Nantes, CNRS, INSERM, l'institut du thorax, Nantes, France
| | - Justina C. Wolters
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Marieke Smit
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Vincent W. Bloks
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Niels J. Kloosterhuis
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Nicolette C. A. Huijkman
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Mirjam H. Koster
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Umesh Tharehalli
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Simon M. de Neck
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Colin Bournez
- Division of Drug Discovery and Safety, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Marceline M. Fuh
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg−Eppendorf, Hamburg, Germany
| | - Jeroen Kuipers
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Sujith Rajan
- Department of Foundations of Medicine, NYU Long Island School of Medicine, Mineola, New York, USA
| | - Alain de Bruin
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Henry N. Ginsberg
- Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, New York, USA
| | - Gerard J. P. van Westen
- Division of Drug Discovery and Safety, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - M. Mahmood Hussain
- Department of Foundations of Medicine, NYU Long Island School of Medicine, Mineola, New York, USA
| | - Ludger Scheja
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg−Eppendorf, Hamburg, Germany
| | - Joerg Heeren
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg−Eppendorf, Hamburg, Germany
| | | | - Bart van de Sluis
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Jan Albert Kuivenhoven
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
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20
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Wang X, Huang R, Wang Y, Zhou W, Hu Y, Yao Y, Cheng K, Li X, Xu B, Zhang J, Xu Y, Zeng F, Zhu Y, Chen XW. Manganese regulation of COPII condensation controls circulating lipid homeostasis. Nat Cell Biol 2023; 25:1650-1663. [PMID: 37884645 DOI: 10.1038/s41556-023-01260-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 09/18/2023] [Indexed: 10/28/2023]
Abstract
Precise control of circulating lipids is instrumental in health and disease. Bulk lipids, carried by specialized lipoproteins, are secreted into the circulation, initially via the coat protein complex II (COPII). How the universal COPII machinery accommodates the abundant yet unconventional lipoproteins remains unclear, let alone its therapeutic translation. Here we report that COPII uses manganese-tuning, self-constrained condensation to selectively drive lipoprotein delivery and set lipid homeostasis in vivo. Serendipitously, adenovirus hijacks the condensation-based transport mechanism, thus enabling the identification of cytosolic manganese as an unexpected control signal. Manganese directly binds the inner COPII coat and enhances its condensation, thereby shifting the assembly-versus-dynamics balance of the transport machinery. Manganese can be mobilized from mitochondria stores to signal COPII, and selectively controls lipoprotein secretion with a distinctive, bell-shaped function. Consequently, dietary titration of manganese enables tailored lipid management that counters pathological dyslipidaemia and atherosclerosis, implicating a condensation-targeting strategy with broad therapeutic potential for cardio-metabolic health.
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Affiliation(s)
- Xiao Wang
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China.
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China.
- PKU-THU Joint Center for Life Sciences, Peking University, Beijing, China.
| | - Runze Huang
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Yawei Wang
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- PKU-THU Joint Center for Life Sciences, Peking University, Beijing, China
| | - Wenjing Zhou
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Yating Hu
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Yuanhang Yao
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Kunlun Cheng
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Xin Li
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Bolin Xu
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Jie Zhang
- Department of Clinical Research Center, Dazhou Hospital, Dazhou, Sichuan, China
| | - Yaowen Xu
- Department of Clinical Research Center, Dazhou Hospital, Dazhou, Sichuan, China
| | - Fanxin Zeng
- Department of Clinical Research Center, Dazhou Hospital, Dazhou, Sichuan, China
| | - Yuangang Zhu
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China
| | - Xiao-Wei Chen
- State Key Laboratory of Membrane Biology, Peking University, Beijing, China.
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, China.
- PKU-THU Joint Center for Life Sciences, Peking University, Beijing, China.
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21
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Wang Y, Kinoshita T. The role of lipid scramblases in regulating lipid distributions at cellular membranes. Biochem Soc Trans 2023; 51:1857-1869. [PMID: 37767549 DOI: 10.1042/bst20221455] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 09/12/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023]
Abstract
Glycerophospholipids, sphingolipids and cholesterol assemble into lipid bilayers that form the scaffold of cellular membranes, in which proteins are embedded. Membrane composition and membrane protein profiles differ between plasma and intracellular membranes and between the two leaflets of a membrane. Lipid distributions between two leaflets are mediated by lipid translocases, including flippases and scramblases. Flippases use ATP to catalyze the inward movement of specific lipids between leaflets. In contrast, bidirectional flip-flop movements of lipids across the membrane are mediated by scramblases in an ATP-independent manner. Scramblases have been implicated in disrupting the lipid asymmetry of the plasma membrane, protein glycosylation, autophagosome biogenesis, lipoprotein secretion, lipid droplet formation and communications between organelles. Although scramblases in plasma membranes were identified over 10 years ago, most progress about scramblases localized in intracellular membranes has been made in the last few years. Herein, we review the role of scramblases in regulating lipid distributions in cellular membranes, focusing primarily on intracellular membrane-localized scramblases.
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Affiliation(s)
- Yicheng Wang
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- Key Laboratory of Biopharmaceutical Preparation and Delivery, Chinese Academy of Sciences, Beijing 100190, China
| | - Taroh Kinoshita
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
- WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
- Center for Infectious Disease Education and Research, Osaka University, Suita, Osaka 565-0871, Japan
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22
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Zalejski J, Sun J, Sharma A. Unravelling the Mystery inside Cells by Using Single-Molecule Fluorescence Imaging. J Imaging 2023; 9:192. [PMID: 37754956 PMCID: PMC10532472 DOI: 10.3390/jimaging9090192] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 09/01/2023] [Accepted: 09/14/2023] [Indexed: 09/28/2023] Open
Abstract
Live-cell imaging is a powerful technique to study the dynamics and mechanics of various biological molecules like proteins, organelles, DNA, and RNA. With the rapid evolution of optical microscopy, our understanding of how these molecules are implicated in the cells' most critical physiological roles deepens. In this review, we focus on how spatiotemporal nanoscale live-cell imaging at the single molecule level allows for profound contributions towards new discoveries in life science. This review will start by summarizing how single-molecule tracking has been used to analyze membrane dynamics, receptor-ligand interactions, protein-protein interactions, inner- and extra-cellular transport, gene expression/transcription, and whole organelle tracking. We then move on to how current authors are trying to improve single-molecule tracking and overcome current limitations by offering new ways of labeling proteins of interest, multi-channel/color detection, improvements in time-lapse imaging, and new methods and programs to analyze the colocalization and movement of targets. We later discuss how single-molecule tracking can be a beneficial tool used for medical diagnosis. Finally, we wrap up with the limitations and future perspectives of single-molecule tracking and total internal reflection microscopy.
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Affiliation(s)
| | | | - Ashutosh Sharma
- Department of Chemistry, University of Illinois Chicago, Chicago, IL 60607, USA; (J.Z.); (J.S.)
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23
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Delosière M, Bernard L, Hurtaud C, Guilleton M, Viala D, Rau A, Bonnet M, Cebo C. Protein signatures of spontaneous lipolysis and lipoprotein lipase activity in cow's milk. J Proteomics 2023; 285:104951. [PMID: 37321301 DOI: 10.1016/j.jprot.2023.104951] [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: 02/23/2023] [Revised: 05/30/2023] [Accepted: 06/01/2023] [Indexed: 06/17/2023]
Abstract
Spontaneous milk lipolysis refers to the breakdown of triacylglycerols in milk. Lipolysis impacts the organoleptic value of milk by causing off-flavours and reduces the technological properties of milk. Lipolysis is caused by lipoprotein lipase (LPL), a tightly regulated enzyme in milk. Our objective was to identify robust biomarkers of lipolysis and putative regulators of LPL enzyme in bovine milk. To achieve this goal, we used feed restriction as a lever to generate highly contrasted samples with regard to milk lipolysis. We combined statistical methods on proteomics data, milk lipolysis and LPL activity values. Following this strategy, we identified CD5L and GP2 as robust biomarkers of high lipolysis in cow milk. We also identified HID1, SURF4 and CUL9 as putative inhibitors of the lipolytic process in the milk. We thus proposed 5 putative biomarkers to be considered in future tools to manage milk lipolysis. SIGNIFICANCE: This manuscript is notable in three aspects. First, this is the first evaluation of the milk proteome relative to milk lipolysis or LPL activity. Second, the relationship between the abundance of proteins and milk traits was evaluated by a combination of univariate and multivariate analyses. Third, we provide a short list of five proteins to be tested in a larger population to feed the pipeline of biomarker discovery.
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Affiliation(s)
- M Delosière
- INRAE, Université Clermont Auvergne, Vetagro Sup, UMRH, 63122, Saint-Genes-Champanelle, France.
| | - L Bernard
- INRAE, Université Clermont Auvergne, Vetagro Sup, UMRH, 63122, Saint-Genes-Champanelle, France
| | - C Hurtaud
- PEGASE, INRAE, Institut Agro, 35590, Saint-Gilles, France
| | - M Guilleton
- INRAE, Université Clermont Auvergne, Vetagro Sup, UMRH, 63122, Saint-Genes-Champanelle, France
| | - D Viala
- INRAE, Université Clermont Auvergne, Vetagro Sup, UMRH, 63122, Saint-Genes-Champanelle, France; INRAE, Université Clermont Auvergne, Vetagro Sup, Metabolomic and Proteomic Exploration Facility (PFEM), 63122, Saint-Genès-Champanelle, France
| | - A Rau
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350, Jouy-en-Josas, France
| | - M Bonnet
- INRAE, Université Clermont Auvergne, Vetagro Sup, UMRH, 63122, Saint-Genes-Champanelle, France
| | - C Cebo
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350, Jouy-en-Josas, France
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24
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Zhang Y, Srivastava V, Zhang B. Mammalian cargo receptors for endoplasmic reticulum-to-Golgi transport: mechanisms and interactions. Biochem Soc Trans 2023:BST20220713. [PMID: 37334845 DOI: 10.1042/bst20220713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/22/2023] [Accepted: 05/30/2023] [Indexed: 06/21/2023]
Abstract
Proteins that are destined to enter the secretory pathway are synthesized on the rough endoplasmic reticulum (ER) and then translocated into the ER lumen, where they undergo posttranslational modifications, folding, and assembly. After passing a quality control system, the cargo proteins are packaged into coat protein complex II (COPII) vesicles to exit the ER. In metazoans, most COPII subunits have multiple paralogs, enabling COPII vesicles the flexibility to transport a diverse range of cargo. The cytoplasmic domains of transmembrane proteins can interact with SEC24 subunits of COPII to enter the ER exit sites. Some transmembrane proteins may also act as cargo receptors that bind soluble secretory proteins within the ER lumen, enabling them to enter COPII vesicles. The cytoplasmic domains of cargo receptors also contain coat protein complex I binding motifs that allow for their cycling back to the ER after unloading their cargo in the ER-Golgi intermediate compartment and cis-Golgi. Once unloaded, the soluble cargo proteins continue maturation through the Golgi before reaching their final destinations. This review provides an overview of receptor-mediated transport of secretory proteins from the ER to the Golgi, with a focus on the current understanding of two mammalian cargo receptors: the LMAN1-MCFD2 complex and SURF4, and their roles in human health and disease.
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Affiliation(s)
- Yuan Zhang
- Genomic Medicine Institute, Lerner Research Institute of Cleveland Clinic, Cleveland, OH, U.S.A
| | - Vishal Srivastava
- Genomic Medicine Institute, Lerner Research Institute of Cleveland Clinic, Cleveland, OH, U.S.A
| | - Bin Zhang
- Genomic Medicine Institute, Lerner Research Institute of Cleveland Clinic, Cleveland, OH, U.S.A
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25
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Tang VT, Abbineni PS, Leprevost FDV, Basrur V, Emmer BT, Nesvizhskii AI, Ginsburg D. Identification of LMAN1 and SURF4 dependent secretory cargoes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.06.535922. [PMID: 37066360 PMCID: PMC10104123 DOI: 10.1101/2023.04.06.535922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Most proteins secreted into the extracellular space are first recruited from the endoplasmic reticulum into coat protein complex II (COPII)-coated vesicles or tubules that facilitate their transport to the Golgi apparatus. Although several secreted proteins have been shown to be actively recruited into COPII vesicles/tubules by the cargo receptors LMAN1 and SURF4, the full cargo repertoire of these receptors is unknown. We now report mass spectrometry analysis of conditioned media and cell lysates from HuH7 cells CRISPR targeted to inactivate the LMAN1 or SURF4 gene. We found that LMAN1 has limited clients in HuH7 cells whereas SURF4 traffics a broad range of cargoes. Analysis of putative SURF4 cargoes suggests that cargo recognition is governed by complex mechanisms rather than interaction with a universal binding motif.
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Affiliation(s)
- Vi T. Tang
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
- Life Sciences Institute, University of Michigan, Ann Arbor, MI
| | | | | | | | - Brian T. Emmer
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Alexey I. Nesvizhskii
- Department of Pathology, University of Michigan, Ann Arbor, MI
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI
| | - David Ginsburg
- Life Sciences Institute, University of Michigan, Ann Arbor, MI
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI
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26
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Shaw JL, Pablo JL, Greka A. Mechanisms of Protein Trafficking and Quality Control in the Kidney and Beyond. Annu Rev Physiol 2023; 85:407-423. [PMID: 36763970 DOI: 10.1146/annurev-physiol-031522-100639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Numerous trafficking and quality control pathways evolved to handle the diversity of proteins made by eukaryotic cells. However, at every step along the biosynthetic pathway, there is the potential for quality control system failure. This review focuses on the mechanisms of disrupted proteostasis. Inspired by diseases caused by misfolded proteins in the kidney (mucin 1 and uromodulin), we outline the general principles of protein biosynthesis, delineate the recognition and degradation pathways targeting misfolded proteins, and discuss the role of cargo receptors in protein trafficking and lipid homeostasis. We also discuss technical approaches including live-cell fluorescent microscopy, chemical screens to elucidate trafficking mechanisms, multiplexed single-cell CRISPR screening platforms to systematically delineate mechanisms of proteostasis, and the advancement of novel tools to degrade secretory and membrane-associated proteins. By focusing on components of trafficking that go awry, we highlight ongoing efforts to understand fundamental mechanisms of disrupted proteostasis and implications for the treatment of human proteinopathies.
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Affiliation(s)
- Jillian L Shaw
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; .,Kidney Disease Initiative, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Juan Lorenzo Pablo
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; .,Kidney Disease Initiative, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Anna Greka
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA; .,Kidney Disease Initiative, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.,Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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27
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Tang VT, Ginsburg D. Cargo selection in endoplasmic reticulum-to-Golgi transport and relevant diseases. J Clin Invest 2023; 133:163838. [PMID: 36594468 PMCID: PMC9797344 DOI: 10.1172/jci163838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Most proteins destined for the extracellular space or various intracellular compartments must traverse the intracellular secretory pathway. The first step is the recruitment and transport of cargoes from the endoplasmic reticulum (ER) lumen to the Golgi apparatus by coat protein complex II (COPII), consisting of five core proteins. Additional ER transmembrane proteins that aid cargo recruitment are referred to as cargo receptors. Gene duplication events have resulted in multiple COPII paralogs present in the mammalian genome. Here, we review the functions of each COPII protein, human disorders associated with each paralog, and evidence for functional conservation between paralogs. We also provide a summary of current knowledge regarding two prototypical cargo receptors in mammals, LMAN1 and SURF4, and their roles in human health and disease.
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Affiliation(s)
- Vi T. Tang
- Department of Molecular and Integrative Physiology,,Life Sciences Institute
| | - David Ginsburg
- Life Sciences Institute,,Department of Internal Medicine,,Department of Human Genetics,,Department of Pediatrics and Communicable Diseases, and,Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan, USA
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28
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Barrabi C, Zhang K, Liu M, Chen X. Pancreatic beta cell ER export in health and diabetes. Front Endocrinol (Lausanne) 2023; 14:1155779. [PMID: 37152949 PMCID: PMC10160654 DOI: 10.3389/fendo.2023.1155779] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 04/10/2023] [Indexed: 05/09/2023] Open
Abstract
In the secretory pathway of the pancreatic beta cell, proinsulin and other secretory granule proteins are first produced in the endoplasmic reticulum (ER). Beta cell ER homeostasis is vital for normal beta cell functions and is maintained by the delicate balance between protein synthesis, folding, export and degradation. Disruption of ER homeostasis leads to beta cell death and diabetes. Among the four components to maintain ER homeostasis, the role of ER export in insulin biogenesis or beta cell survival was not well-understood. COPII (coat protein complex II) dependent transport is a conserved mechanism for most cargo proteins to exit ER and transport to Golgi apparatus. Emerging evidence began to reveal a critical role of COPII-dependent ER export in beta cells. In this review, we will first discuss the basic components of the COPII transport machinery, the regulation of cargo entry and COPII coat assembly in mammalian cells, and the general concept of receptor-mediated cargo sorting in COPII vesicles. On the basis of these general discussions, the current knowledge and recent developments specific to the beta cell COPII dependent ER export are summarized under normal and diabetic conditions.
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Affiliation(s)
- Cesar Barrabi
- Department of Physiology, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Kezhong Zhang
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Xuequn Chen
- Department of Physiology, School of Medicine, Wayne State University, Detroit, MI, United States
- *Correspondence: Xuequn Chen,
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29
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Chen A, Ding WX, Ni HM. Scramblases as Regulators of Autophagy and Lipid Homeostasis: Implications for NAFLD. AUTOPHAGY REPORTS 2022; 1:143-160. [PMID: 35509327 PMCID: PMC9066413 DOI: 10.1080/27694127.2022.2055724] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Equilibration of phospholipids between the two monolayers of the lipid bilayer of cellular membranes is mediated by scramblases acting as phospholipid shuttling proteins that are critical for cellular function, particularly during inter-organelle contact. Recent work has identified several protein scramblases, including TMEM41B, VMP1 and ATG9 that are critical in autophagy. More recently, ATG9, TMEM41B, and VMP1 have also been discovered to be important regulators of cellular lipid homeostasis. In vivo mouse models involving ablation of TMEM41B in liver have shown that knockout of these proteins can lead to rapid development of non-alcoholic steatohepatitis (NASH) and systemic dyslipidemia, though this has not been explored yet with ATG9. The resulting phenotype is likely due to the combined effects of a severe lipid secretion defect caused by stalled neutral lipids export from the endoplasmic reticulum (ER) membrane bilayer coupled with increased lipogenesis. Here we briefly discuss recent exciting findings on the topic of scramblases in autophagy, their relevance to human non-alcoholic fatty liver disease (NAFLD)/NASH, as well as future directions in this research.
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Affiliation(s)
- Allen Chen
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, USA
- Department of Internal Medicine, The University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Hong-Min Ni
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, USA
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30
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Tang X, Wang T, Guo Y. Export of polybasic motif-containing secretory proteins BMP8A and SFRP1 from the endoplasmic reticulum is regulated by surfeit locus protein 4. J Biol Chem 2022; 298:102687. [PMID: 36370847 PMCID: PMC9731852 DOI: 10.1016/j.jbc.2022.102687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 10/29/2022] [Accepted: 11/01/2022] [Indexed: 11/11/2022] Open
Abstract
In the conventional secretory pathway, cargo receptors play important roles in exporting newly synthesized secretory proteins from the endoplasmic reticulum (ER). We previously showed that a cargo receptor, surfeit locus protein 4 (SURF4), promotes ER export of a soluble signaling molecule, sonic hedgehog, via recognizing the polybasic residues within its Cardin-Weintraub motif. In addition to sonic hedgehog, we found 30 more secretory proteins containing the polybasic motif (K/R)(K/R)(K/R)XX(K/R)(K/R), but whether SURF4 plays a general role in mediating ER export of these secretory proteins is unclear. Here, we analyzed the trafficking of four of these secretory proteins: desert hedgehog, Indian hedgehog, bone morphogenetic protein 8A (BMP8A), and secreted frizzled-related protein 1 (SFRP1). We found that the polybasic motifs contained in these cargo proteins are important for their ER export. Further analyses indicated that the polybasic motifs of BMP8A and SFRP1 interact with the triacidic motif on the predicted first luminal domain of SURF4. These interactions with SURF4 are essential and sufficient for the ER-to-Golgi trafficking of BMP8A and SFRP1. Moreover, we demonstrated that SURF4 localizes at a subpopulation of ER exit sites to regulate the ER export of its clients. Taken together, these results suggest that SURF4 is recruited to specific ER exit sites and plays a general role in capturing polybasic motif-containing secretory cargo proteins through electrostatic interactions.
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Affiliation(s)
- Xiao Tang
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China,Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Tingxuan Wang
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yusong Guo
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China,Hong Kong University of Science and Technology Shenzhen Research Institute, Shenzhen, China,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China,For correspondence: Yusong Guo
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31
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TMEM41B, a novel ER phospholipid scramblase mediating systemic lipid metabolism. Acta Biochim Biophys Sin (Shanghai) 2022; 54:1761-1764. [PMID: 36604140 PMCID: PMC9828732 DOI: 10.3724/abbs.2022168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Stomberski CT, Venetos NM, Zhou HL, Qian Z, Collison BR, Field SJ, Premont RT, Stamler JS. A multienzyme S-nitrosylation cascade regulates cholesterol homeostasis. Cell Rep 2022; 41:111538. [PMID: 36288700 PMCID: PMC9667709 DOI: 10.1016/j.celrep.2022.111538] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/03/2022] [Accepted: 09/30/2022] [Indexed: 11/03/2022] Open
Abstract
Accumulating evidence suggests that protein S-nitrosylation is enzymatically regulated and that specificity in S-nitrosylation derives from dedicated S-nitrosylases and denitrosylases that conjugate and remove S-nitrosothiols, respectively. Here, we report that mice deficient in the protein denitrosylase SCoR2 (S-nitroso-Coenzyme A Reductase 2; AKR1A1) exhibit marked reductions in serum cholesterol due to reduced secretion of the cholesterol-regulating protein PCSK9. SCoR2 associates with endoplasmic reticulum (ER) secretory machinery to control an S-nitrosylation cascade involving ER cargo-selection proteins SAR1 and SURF4, which moonlight as S-nitrosylases. SAR1 acts as a SURF4 nitrosylase and SURF4 as a PCSK9 nitrosylase to inhibit PCSK9 secretion, while SCoR2 counteracts nitrosylase activity by promoting PCSK9 denitrosylation. Inhibition of PCSK9 by an NO-based drug requires nitrosylase activity, and small-molecule inhibition of SCoR2 phenocopies the PCSK9-mediated reductions in cholesterol observed in SCoR2-deficient mice. Our results reveal enzymatic machinery controlling cholesterol levels through S-nitrosylation and suggest a distinct treatment paradigm for cardiovascular disease.
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Affiliation(s)
- Colin T Stomberski
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44016, USA; Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Nicholas M Venetos
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44016, USA; Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Hua-Lin Zhou
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44016, USA; Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH 44016, USA
| | - Zhaoxia Qian
- Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH 44016, USA
| | - Bryce R Collison
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Seth J Field
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44016, USA; Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH 44016, USA
| | - Richard T Premont
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44016, USA; Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH 44016, USA
| | - Jonathan S Stamler
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44016, USA; Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH 44016, USA.
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33
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Raja R, Fonseka O, Ganenthiran H, Liu W. The multifaceted roles of ER and Golgi in metabolic cardiomyopathy. Front Cardiovasc Med 2022; 9:999044. [PMID: 36119738 PMCID: PMC9479098 DOI: 10.3389/fcvm.2022.999044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/15/2022] [Indexed: 01/10/2023] Open
Abstract
Metabolic cardiomyopathy is a significant global financial and health challenge; however, pathophysiological mechanisms governing this entity remain poorly understood. Among the main features of metabolic cardiomyopathy, the changes to cellular lipid metabolism have been studied and targeted for the discovery of novel treatment strategies obtaining contrasting results. The endoplasmic reticulum (ER) and Golgi apparatus (GA) carry out protein modification, sorting, and secretion activities that are more commonly studied from the perspective of protein quality control; however, they also drive the maintenance of lipid homeostasis. In response to metabolic stress, ER and GA regulate the expression of genes involved in cardiac lipid biogenesis and participate in lipid droplet formation and degradation. Due to the varied roles these organelles play, this review will focus on recapitulating the alterations and crosstalk between ER, GA, and lipid metabolism in cardiac metabolic syndrome.
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Gomez-Navarro N, Maldutyte J, Poljak K, Peak-Chew SY, Orme J, Bisnett BJ, Lamb CH, Boyce M, Gianni D, Miller EA. Selective inhibition of protein secretion by abrogating receptor-coat interactions during ER export. Proc Natl Acad Sci U S A 2022; 119:e2202080119. [PMID: 35901214 PMCID: PMC9351455 DOI: 10.1073/pnas.2202080119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 06/01/2022] [Indexed: 01/03/2023] Open
Abstract
Protein secretion is an essential process that drives cell growth, movement, and communication. Protein traffic within the secretory pathway occurs via transport intermediates that bud from one compartment and fuse with a downstream compartment to deliver their contents. Here, we explore the possibility that protein secretion can be selectively inhibited by perturbing protein-protein interactions that drive capture into transport vesicles. Human proprotein convertase subtilisin/kexin type 9 (PCSK9) is a determinant of cholesterol metabolism whose secretion is mediated by a specific cargo adaptor protein, SEC24A. We map a series of protein-protein interactions between PCSK9, its endoplasmic reticulum (ER) export receptor SURF4, and SEC24A that mediate secretion of PCSK9. We show that the interaction between SURF4 and SEC24A can be inhibited by 4-phenylbutyrate (4-PBA), a small molecule that occludes a cargo-binding domain of SEC24. This inhibition reduces secretion of PCSK9 and additional SURF4 clients that we identify by mass spectrometry, leaving other secreted cargoes unaffected. We propose that selective small-molecule inhibition of cargo recognition by SEC24 is a potential therapeutic intervention for atherosclerosis and other diseases that are modulated by secreted proteins.
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Affiliation(s)
- Natalia Gomez-Navarro
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Julija Maldutyte
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Kristina Poljak
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Sew-Yeu Peak-Chew
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Jonathon Orme
- Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, CB2 0AA, United Kingdom
| | - Brittany J. Bisnett
- Department of Biochemistry, Duke University School of Medicine, Durham, NC27710, USA
| | - Caitlin H. Lamb
- Department of Biochemistry, Duke University School of Medicine, Durham, NC27710, USA
| | - Michael Boyce
- Department of Biochemistry, Duke University School of Medicine, Durham, NC27710, USA
| | - Davide Gianni
- Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, CB2 0AA, United Kingdom
| | - Elizabeth A. Miller
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
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35
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Shen Y, Gu HM, Zhai L, Wang B, Qin S, Zhang DW. The role of hepatic Surf4 in lipoprotein metabolism and the development of atherosclerosis in apoE -/- mice. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159196. [PMID: 35803528 DOI: 10.1016/j.bbalip.2022.159196] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/25/2022] [Accepted: 06/30/2022] [Indexed: 11/26/2022]
Abstract
Elevated plasma levels of low-density lipoprotein-C (LDL-C) increase the risk of atherosclerotic cardiovascular disease. Circulating LDL is derived from very low-density lipoprotein (VLDL) metabolism and cleared by LDL receptor (LDLR). We have previously demonstrated that cargo receptor Surfeit 4 (Surf4) mediates VLDL secretion. Inhibition of hepatic Surf4 impairs VLDL secretion, significantly reduces plasma LDL-C levels, and markedly mitigates the development of atherosclerosis in LDLR knockout (Ldlr-/-) mice. Here, we investigated the role of Surf4 in lipoprotein metabolism and the development of atherosclerosis in another commonly used mouse model of atherosclerosis, apolipoprotein E knockout (apoE-/-) mice. Adeno-associated viral shRNA was used to silence Surf4 expression mainly in the liver of apoE-/- mice. In apoE-/- mice fed a regular chow diet, knockdown of Surf4 expression significantly reduced triglyceride secretion and plasma levels of non-HDL cholesterol and triglycerides without causing hepatic lipid accumulation or liver damage. When Surf4 was knocked down in apoE-/- mice fed the Western-type diet, we observed a significant reduction in plasma levels of non-HDL cholesterol, but not triglycerides. Knockdown of Surf4 did not increase hepatic cholesterol and triglyceride levels or cause liver damage, but significantly diminished atherosclerosis lesions. Therefore, our findings indicate the potential of hepatic Surf4 inhibition as a novel therapeutic strategy to reduce the risk of atherosclerotic cardiovascular disease.
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Affiliation(s)
- Yishi Shen
- Group on the Molecular and Cell Biology of Lipids and Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Hong-Mei Gu
- Group on the Molecular and Cell Biology of Lipids and Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Lei Zhai
- Institute of Atherosclerosis in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Binxiang Wang
- Institute of Atherosclerosis in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China
| | - Shucun Qin
- Institute of Atherosclerosis in Shandong First Medical University (Shandong Academy of Medical Sciences), Taian, China.
| | - Da-Wei Zhang
- Group on the Molecular and Cell Biology of Lipids and Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
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36
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Markowitz RHG, LaBella AL, Shi M, Rokas A, Capra JA, Ferguson JF, Mosley JD, Bordenstein SR. Microbiome-associated human genetic variants impact phenome-wide disease risk. Proc Natl Acad Sci U S A 2022; 119:e2200551119. [PMID: 35749358 PMCID: PMC9245617 DOI: 10.1073/pnas.2200551119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/29/2022] [Indexed: 12/26/2022] Open
Abstract
Human genetic variation associates with the composition of the gut microbiome, yet its influence on clinical traits remains largely unknown. We analyzed the consequences of nearly a thousand gut microbiome-associated variants (MAVs) on phenotypes reported in electronic health records from tens of thousands of individuals. We discovered and replicated associations of MAVs with neurological, metabolic, digestive, and circulatory diseases. Five significant MAVs in these categories correlate with the relative abundance of microbes down to the strain level. We also demonstrate that these relationships are independently observed and concordant with microbe by disease associations reported in case-control studies. Moreover, a selective sweep and population differentiation impacted some disease-linked MAVs. Combined, these findings establish triad relationships among the human genome, microbiome, and disease. Consequently, human genetic influences may offer opportunities for precision diagnostics of microbiome-associated diseases but also highlight the relevance of genetic background for microbiome modulation and therapeutics.
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Affiliation(s)
- Robert H. George Markowitz
- Vanderbilt Microbiome Innovation Center, Vanderbilt University, Nashville, TN 37232
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232
| | | | - Mingjian Shi
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232
| | - John A. Capra
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA 94143
- Bakar Computational Health Sciences Institute, University of California, San Francisco, CA 94143
| | - Jane F. Ferguson
- Vanderbilt Microbiome Innovation Center, Vanderbilt University, Nashville, TN 37232
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Jonathan D. Mosley
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Seth R. Bordenstein
- Vanderbilt Microbiome Innovation Center, Vanderbilt University, Nashville, TN 37232
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Pathology, Microbiology, and Immunology, School of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
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37
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Cui X, Zhang Y, Lu Y, Xiang M. ROS and Endoplasmic Reticulum Stress in Pulmonary Disease. Front Pharmacol 2022; 13:879204. [PMID: 35559240 PMCID: PMC9086276 DOI: 10.3389/fphar.2022.879204] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 03/11/2022] [Indexed: 12/25/2022] Open
Abstract
Pulmonary diseases are main causes of morbidity and mortality worldwide. Current studies show that though specific pulmonary diseases and correlative lung-metabolic deviance own unique pathophysiology and clinical manifestations, they always tend to exhibit common characteristics including reactive oxygen species (ROS) signaling and disruptions of proteostasis bringing about accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER). ER is generated by the unfolded protein response. When the adaptive unfolded protein response (UPR) fails to preserve ER homeostasis, a maladaptive or terminal UPR is engaged, leading to the disruption of ER integrity and to apoptosis, which is called ER stress. The ER stress mainly includes the accumulation of misfolded and unfolded proteins in lumen and the disorder of Ca2+ balance. ROS mediates several critical aspects of the ER stress response. We summarize the latest advances in of the UPR and ER stress in the pathogenesis of pulmonary disease and discuss potential therapeutic strategies aimed at restoring ER proteostasis in pulmonary disease.
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Affiliation(s)
- Xiangning Cui
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yang Zhang
- First Clinical Medical School, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Yingdong Lu
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Mi Xiang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
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Cargo receptor Surf4 regulates endoplasmic reticulum export of proinsulin in pancreatic β-cells. Commun Biol 2022; 5:458. [PMID: 35562580 PMCID: PMC9106718 DOI: 10.1038/s42003-022-03417-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 04/26/2022] [Indexed: 11/08/2022] Open
Abstract
Insulin is an essential peptide hormone that maintains blood glucose levels. Although the mechanisms underlying insulin exocytosis have been investigated, the mechanism of proinsulin export from the endoplasmic reticulum (ER) remains unclear. Here, we demonstrated that Surf4, a cargo receptor homolog, regulates the ER export of proinsulin via its recruitment to ER exit sites (ERES). Under high-glucose conditions, Surf4 expression was upregulated, and Surf4 proteins mainly localized to the ER at a steady state and accumulated in the ERES, along with proinsulin in rat insulinoma INS-1 cells. Surf4-knockdown resulted in proinsulin retention in the ER and decreased the levels of mature insulin in secretory granules, thereby significantly reducing insulin secretion. Surf4 forms an oligomer and can physically interact with proinsulin and Sec12, essential for COPII vesicle formation. Our findings suggest that Surf4 interacts with proinsulin and delivers it into COPII vesicles for ER export in co-operation with Sec12 and COPII.
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Borén J, Taskinen MR, Björnson E, Packard CJ. Metabolism of triglyceride-rich lipoproteins in health and dyslipidaemia. Nat Rev Cardiol 2022; 19:577-592. [PMID: 35318466 DOI: 10.1038/s41569-022-00676-y] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/02/2022] [Indexed: 02/07/2023]
Abstract
Accumulating evidence points to the causal role of triglyceride-rich lipoproteins and their cholesterol-enriched remnants in atherogenesis. Genetic studies in particular have not only revealed a relationship between plasma triglyceride levels and the risk of atherosclerotic cardiovascular disease, but have also identified key proteins responsible for the regulation of triglyceride transport. Kinetic studies in humans using stable isotope tracers have been especially useful in delineating the function of these proteins and revealing the hitherto unappreciated complexity of triglyceride-rich lipoprotein metabolism. Given that triglyceride is an essential energy source for mammals, triglyceride transport is regulated by numerous mechanisms that balance availability with the energy demands of the body. Ongoing investigations are focused on determining the consequences of dysregulation as a result of either dietary imprudence or genetic variation that increases the risk of atherosclerosis and pancreatitis. The identification of molecular control mechanisms involved in triglyceride metabolism has laid the groundwork for a 'precision-medicine' approach to therapy. Novel pharmacological agents under development have specific molecular targets within a regulatory framework, and their deployment heralds a new era in lipid-lowering-mediated prevention of disease. In this Review, we outline what is known about the dysregulation of triglyceride transport in human hypertriglyceridaemia.
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Affiliation(s)
- Jan Borén
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden.
| | - Marja-Riitta Taskinen
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Elias Björnson
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Chris J Packard
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
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A SURF4-to-proteoglycan relay mechanism that mediates the sorting and secretion of a tagged variant of sonic hedgehog. Proc Natl Acad Sci U S A 2022; 119:e2113991119. [PMID: 35271396 PMCID: PMC8931250 DOI: 10.1073/pnas.2113991119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
SignificanceSonic Hedgehog (Shh) is a key signaling molecule that plays important roles in embryonic patterning, cell differentiation, and organ development. Although fundamentally important, the molecular mechanisms that regulate secretion of newly synthesized Shh are still unclear. Our study reveals a role for the cargo receptor, SURF4, in facilitating export of Shh from the endoplasmic reticulum (ER) via a ER export signal. In addition, our study provides evidence suggesting that proteoglycans promote the dissociation of SURF4 from Shh at the Golgi, suggesting a SURF4-to-proteoglycan relay mechanism. These analyses provide insight into an important question in cell biology: how do cargo receptors capture their clients in one compartment, then disengage at their destination?
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41
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Yan R, Chen K, Wang B, Xu K. SURF4-induced tubular ERGIC selectively expedites ER-to-Golgi transport. Dev Cell 2022; 57:512-525.e8. [PMID: 35051356 PMCID: PMC8891076 DOI: 10.1016/j.devcel.2021.12.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 12/09/2021] [Accepted: 12/17/2021] [Indexed: 11/25/2022]
Abstract
The endoplasmic reticulum (ER)-to-Golgi transport is critical to protein secretion and intracellular sorting. Here, we report a highly elongated tubular ER-Golgi intermediate compartment (t-ERGIC) that selectively expedites the ER-to-Golgi transport for soluble cargoes of the receptor SURF4. Lacking the canonical ERGIC marker ERGIC-53 yet positive for the small GTPases Rab1A/B, the t-ERGIC is further marked by its extraordinarily elongated and thinned shape. With its large surface-to-volume ratio, high intracellular traveling speeds, and ER-Golgi recycling capabilities, the t-ERGIC accelerates the trafficking of SURF4-bound cargoes. The biogenesis and cargo selectivity of t-ERGIC both depend on SURF4, which recognizes the N terminus of soluble cargoes and co-clusters with the selected cargoes to expand the ER-exit site. In the steady state, the t-ERGIC-mediated fast ER-to-Golgi transport is antagonized by the KDEL-mediated ER retrieval. Together, our results argue that specific cargo-receptor interactions give rise to distinct transport carriers that regulate the trafficking kinetics.
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Affiliation(s)
- Rui Yan
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
| | - Kun Chen
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA, 94720,Chan Zuckerberg Biohub, San Francisco, CA, USA, 94158
| | - Bowen Wang
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA, 94720,Chan Zuckerberg Biohub, San Francisco, CA, USA, 94158
| | - Ke Xu
- Department of Chemistry & California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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42
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Amelioration of hepatic steatosis by dietary essential amino acid-induced ubiquitination. Mol Cell 2022; 82:1528-1542.e10. [PMID: 35245436 DOI: 10.1016/j.molcel.2022.01.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 12/14/2021] [Accepted: 01/25/2022] [Indexed: 12/30/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a global health concern with no approved drugs. High-protein dietary intervention is currently the most effective treatment. However, its underlying mechanism is unknown. Here, using Drosophila oenocytes, the specialized hepatocyte-like cells, we find that dietary essential amino acids ameliorate hepatic steatosis by inducing polyubiquitination of Plin2, a lipid droplet-stabilizing protein. Leucine and isoleucine, two branched-chain essential amino acids, strongly bind to and activate the E3 ubiquitin ligase Ubr1, targeting Plin2 for degradation. We further show that the amino acid-induced Ubr1 activity is necessary to prevent steatosis in mouse livers and cultured human hepatocytes, providing molecular insight into the anti-NAFLD effects of dietary protein/amino acids. Importantly, split-intein-mediated trans-splicing expression of constitutively active UBR2, an Ubr1 family member, significantly ameliorates obesity-induced and high fat diet-induced hepatic steatosis in mice. Together, our results highlight activation of Ubr1 family proteins as a promising strategy in NAFLD treatment.
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43
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Devireddy S, Ferguson SM. Efficient progranulin exit from the ER requires its interaction with prosaposin, a Surf4 cargo. J Cell Biol 2022; 221:e202104044. [PMID: 34919127 PMCID: PMC8689666 DOI: 10.1083/jcb.202104044] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 10/11/2021] [Accepted: 11/15/2021] [Indexed: 11/22/2022] Open
Abstract
Progranulin is a lysosomal protein whose haploinsufficiency causes frontotemporal dementia, while homozygous loss of progranulin causes neuronal ceroid lipofuscinosis, a lysosomal storage disease. The sensitivity of cells to progranulin deficiency raises important questions about how cells coordinate intracellular trafficking of progranulin to ensure its efficient delivery to lysosomes. In this study, we discover that progranulin interactions with prosaposin, another lysosomal protein, first occur within the lumen of the endoplasmic reticulum (ER) and are required for the efficient ER exit of progranulin. Mechanistically, we identify an interaction between prosaposin and Surf4, a receptor that promotes loading of lumenal cargos into COPII-coated vesicles, and establish that Surf4 is critical for the efficient export of progranulin and prosaposin from the ER. Collectively, this work demonstrates that a network of interactions occurring early in the secretory pathway promote the ER exit and subsequent lysosomal delivery of newly translated progranulin and prosaposin.
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Affiliation(s)
| | - Shawn M. Ferguson
- Departments of Cell Biology and Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, Wu Tsai Institute, Yale University School of Medicine, New Haven, CT
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Cai GP, Liu YL, Luo LP, Xiao Y, Jiang TJ, Yuan J, Wang M. Alkbh1-mediated DNA N6-methyladenine modification regulates bone marrow mesenchymal stem cell fate during skeletal aging. Cell Prolif 2022; 55:e13178. [PMID: 35018683 PMCID: PMC8828262 DOI: 10.1111/cpr.13178] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/25/2021] [Indexed: 12/17/2022] Open
Abstract
Objectives DNA N6‐methyladenine (N6‐mA) demethylase Alkbh1 participates in regulating osteogenic differentiation of mesenchymal stem cell (MSCs) and vascular calcification. However, the role of Alkbh1 in bone metabolism remains unclear. Materials and Methods Bone marrow mesenchymal stem cells (BMSCs)‐specific Alkbh1 knockout mice were used to investigate the role of Alkbh1 in bone metabolism. Western blot, qRT‐PCR, and immunofluorescent staining were used to evaluate the expression of Alkbh1 or optineurin (optn). Micro‐CT, histomorphometric analysis, and calcein double‐labeling assay were used to evaluate bone phenotypes. Cell staining and qRT‐PCR were used to evaluate the osteogenic or adipogenic differentiation of BMSCs. Dot blotting was used to detect the level of N6‐mA in genomic DNA. Chromatin immunoprecipitation (Chip) assays were used to identify critical targets of Alkbh1. Alkbh1 adeno‐associated virus was used to overexpress Alkbh1 in aged mice. Results Alkbh1 expression in BMSCs declined during aging. Knockout of Alkbh1 promoted adipogenic differentiation of BMSCs while inhibited osteogenic differentiation. BMSC‐specific Alkbh1 knockout mice exhibited reduced bone mass and increased marrow adiposity. Mechanistically, we identified optn as the downstream target through which Alkbh1‐mediated DNA m6A modification regulated BMSCs fate. Overexpression of Alkbh1 attenuated bone loss and marrow fat accumulation in aged mice. Conclusions Our findings demonstrated that Alkbh1 regulated BMSCs fate and bone‐fat balance during skeletal aging and provided a potential target for the treatment of osteoporosis.
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Affiliation(s)
- Guang-Ping Cai
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, P. R. China
| | - Ya-Lin Liu
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, P. R. China
| | - Li-Ping Luo
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, P. R. China
| | - Ye Xiao
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, P. R. China
| | - Tie-Jian Jiang
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, P. R. China
| | - Jian Yuan
- Department of Neurosurgery, Xiangya Hospital of Central South University, Changsha, China
| | - Min Wang
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, P. R. China
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45
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A tango for coats and membranes: New insights into ER-to-Golgi traffic. Cell Rep 2022; 38:110258. [DOI: 10.1016/j.celrep.2021.110258] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 11/17/2021] [Accepted: 12/21/2021] [Indexed: 12/30/2022] Open
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Chang X, Zhao Y, Qin S, Wang H, Wang B, Zhai L, Liu B, Gu HM, Zhang DW. Loss of Hepatic Surf4 Depletes Lipid Droplets in the Adrenal Cortex but Does Not Impair Adrenal Hormone Production. Front Cardiovasc Med 2021; 8:764024. [PMID: 34859075 PMCID: PMC8631933 DOI: 10.3389/fcvm.2021.764024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 10/20/2021] [Indexed: 11/13/2022] Open
Abstract
The adrenal gland produces steroid hormones to play essential roles in regulating various physiological processes. Our previous studies showed that knockout of hepatic Surf4 (Surf4LKO) markedly reduced fasting plasma total cholesterol levels in adult mice, including low-density lipoprotein and high-density lipoprotein cholesterol. Here, we found that plasma cholesterol levels were also dramatically reduced in 4-week-old young mice and non-fasted adult mice. Circulating lipoprotein cholesterol is an important source of the substrate for the production of adrenal steroid hormones. Therefore, we investigated whether adrenal steroid hormone production was affected in Surf4LKO mice. We observed that lacking hepatic Surf4 essentially eliminated lipid droplets and significantly reduced cholesterol levels in the adrenal gland; however, plasma levels of aldosterone and corticosterone were comparable in Surf4LKO and the control mice under basal and stress conditions. Further analysis revealed that mRNA levels of genes encoding enzymes important for hormone synthesis were not altered, whereas the expression of scavenger receptor class B type I (SR-BI), low-density lipoprotein receptor (LDLR) and 3-hydroxy-3-methyl-glutaryl-CoA reductase was significantly increased in the adrenal gland of Surf4LKO mice, indicating increased de novo cholesterol biosynthesis and enhanced LDLR and SR-BI-mediated lipoprotein cholesterol uptake. We also observed that the nuclear form of SREBP2 was increased in the adrenal gland of Surf4 LKO mice. Taken together, these findings indicate that the very low levels of circulating lipoprotein cholesterol in Surf4LKO mice cause a significant reduction in adrenal cholesterol levels but do not significantly affect adrenal steroid hormone production. Reduced adrenal cholesterol levels activate SREBP2 and thus increase the expression of genes involved in cholesterol biosynthesis, which increases de novo cholesterol synthesis to compensate for the loss of circulating lipoprotein-derived cholesterol in the adrenal gland of Surf4LKO mice.
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Affiliation(s)
- Xiaole Chang
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Yongfang Zhao
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Shucun Qin
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Hao Wang
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Bingxiang Wang
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Lei Zhai
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Boyan Liu
- Institute of Atherosclerosis, College of Basic Medical Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai'an, China
| | - Hong-Mei Gu
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Da-Wei Zhang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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47
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Wang L, Liu H, Zhang X, Song E, Wang Y, Xu T, Li Z. WFS1 functions in ER export of vesicular cargo proteins in pancreatic β-cells. Nat Commun 2021; 12:6996. [PMID: 34848728 PMCID: PMC8632972 DOI: 10.1038/s41467-021-27344-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 11/11/2021] [Indexed: 11/11/2022] Open
Abstract
The sorting of soluble secretory proteins from the endoplasmic reticulum (ER) to the Golgi complex is mediated by coat protein complex II (COPII) vesicles and thought to required specific ER membrane cargo-receptor proteins. However, these receptors remain largely unknown. Herein, we show that ER to Golgi transfer of vesicular cargo proteins requires WFS1, an ER-associated membrane protein whose loss of function leads to Wolfram syndrome. Mechanistically, WFS1 directly binds to vesicular cargo proteins including proinsulin via its ER luminal C-terminal segment, whereas pathogenic mutations within this region disrupt the interaction. The specific ER export signal encoded in the cytosolic N-terminal segment of WFS1 is recognized by the COPII subunit SEC24, generating mature COPII vesicles that traffic to the Golgi complex. WFS1 deficiency leads to abnormal accumulation of proinsulin in the ER, impeding the proinsulin processing as well as insulin secretion. This work identifies a vesicular cargo receptor for ER export and suggests that impaired peptide hormone transport underlies diabetes resulting from pathogenic WFS1 mutations. The role of cargo receptors in proinsulin export from the ER is unclear. Here, the authors identify the WFS1 protein, which is mutated in Wolfram syndrome and associated with diabetes, as an ER to Golgi cargo receptor required for normal insulin processing and secretion.
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Affiliation(s)
| | - Hongyang Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xiaofei Zhang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Eli Song
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - You Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Tao Xu
- Guangzhou Laboratory, Guangzhou, China. .,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China. .,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China. .,Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China.
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48
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Wu L, He S, Ye W, Shen J, Zhao K, Zhang Y, Zhang R, Wei J, Cao S, Chen K, Le R, Xi C, Kou X, Zhao Y, Wang H, Kang L, Gao S. Surf4 facilitates reprogramming by activating the cellular response to endoplasmic reticulum stress. Cell Prolif 2021; 54:e13133. [PMID: 34585448 PMCID: PMC8560622 DOI: 10.1111/cpr.13133] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES Maternal factors that are enriched in oocytes have attracted great interest as possible key factors in somatic cell reprogramming. We found that surfeit locus protein 4 (Surf4), a maternal factor, can facilitate the generation of induced pluripotent stem cells (iPSCs) previously, but the mechanism remains elusive. MATERIALS AND METHODS In this study, we investigated the function and mechanism of Surf4 in somatic cell reprogramming using a secondary reprogramming system. Alkaline phosphatase (AP) staining, qPCR and immunofluorescence (IF) staining of expression of related markers were used to evaluate efficiency of iPSCs derived from mouse embryonic fibroblasts. Embryoid body and teratoma formation assays were performed to evaluate the differentiation ability of the iPSC lines. RNA-seq, qPCR and western blot analysis were applied to validate the downstream targets of Surf4. RESULTS Surf4 can significantly facilitate the generation of iPSCs in a proliferation-independent manner. When co-expressed with Oct4, Sox2, Klf4 and c-Myc (OSKM), Surf4 can activate the response to endoplasmic reticulum (ER) stress at the early stage of reprogramming. We further demonstrated that Hspa5, a major ER chaperone, and the active spliced form of Xbp1 (sXbp1), a major mediator of ER stress, can mimic the effects of Surf4 on somatic cell reprogramming. Concordantly, blocking the unfolded protein response compromises the effect of Surf4 on reprogramming. CONCLUSIONS Surf4 promotes somatic cell reprogramming by activating the response to ER stress.
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Affiliation(s)
- Li Wu
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Shengxiang He
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China.,Anhui Toneker Biotechnology Co., Ltd., Jinzhai, China
| | - Wen Ye
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jiacheng Shen
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Kun Zhao
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yanping Zhang
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Ran Zhang
- Anhui Toneker Biotechnology Co., Ltd., Jinzhai, China
| | - Junhao Wei
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Shuyuan Cao
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Kang Chen
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Rongrong Le
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China.,Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Chenxiang Xi
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Xiaochen Kou
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China.,Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yanhong Zhao
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China.,Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Hong Wang
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China.,Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Lan Kang
- Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China.,Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Institute for Regenerative Medicine, Shanghai East Hospital, Tongji University, Shanghai, China
| | - Shaorong Gao
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China.,Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
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Abstract
Genetic manipulation in mice allows the discovery of gene function and biological mechanisms in vivo. The widely used Cre/LoxP system usually takes months to years especially when starting with the production of floxed alleles of a new gene of interest (GOI). Here, we describe a protocol using the CRISPR-Cas9 system to acutely inactivate the GOI in adult mice. This protocol enables hepatocyte-specific gene editing within 4 weeks in adult mice and avoids compensatory effects of traditional gene inactivation initiated during various developmental stages. For complete details on the use and execution of this protocol, please refer to Wang et al. (2020).
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Affiliation(s)
- Xiao Wang
- School of Life Sciences, Peking University, Beijing 100871, China
| | - Bo-Lin Xu
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Xiao-Wei Chen
- Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
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50
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An in vitro vesicle formation assay reveals cargo clients and factors that mediate vesicular trafficking. Proc Natl Acad Sci U S A 2021; 118:2101287118. [PMID: 34433667 PMCID: PMC8536394 DOI: 10.1073/pnas.2101287118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein sorting in the secretory pathway is a fundamentally important cellular process, but the clients of a specific cargo sorting machinery remains largely underinvestigated. Here, utilizing a vesicle formation assay to profile proteins associated with vesicles, we identified cytosolic proteins that are associated with vesicle membranes in a GTP-dependent manner or that interact with GTP-bound Sar1A. We found that two of them, FAM84B and PRRC1, regulate anterograde trafficking. Moreover, we revealed specific clients of two export adaptors, SURF4 and ERGIC53. These analyses demonstrate that our approach is powerful to identify factors that regulate vesicular trafficking and to uncover clients of specific cargo receptors, providing a robust method to reveal insights into the secretory pathway. The fidelity of protein transport in the secretory pathway relies on the accurate sorting of proteins to their correct destinations. To deepen our understanding of the underlying molecular mechanisms, it is important to develop a robust approach to systematically reveal cargo proteins that depend on specific sorting machinery to be enriched into transport vesicles. Here, we used an in vitro assay that reconstitutes packaging of human cargo proteins into vesicles to quantify cargo capture. Quantitative mass spectrometry (MS) analyses of the isolated vesicles revealed cytosolic proteins that are associated with vesicle membranes in a GTP-dependent manner. We found that two of them, FAM84B (also known as LRAT domain containing 2 or LRATD2) and PRRC1, contain proline-rich domains and regulate anterograde trafficking. Further analyses revealed that PRRC1 is recruited to endoplasmic reticulum (ER) exit sites, interacts with the inner COPII coat, and its absence increases membrane association of COPII. In addition, we uncovered cargo proteins that depend on GTP hydrolysis to be captured into vesicles. Comparing control cells with cells depleted of the cargo receptors, SURF4 or ERGIC53, we revealed specific clients of each of these two export adaptors. Our results indicate that the vesicle formation assay in combination with quantitative MS analysis is a robust and powerful tool to uncover novel factors that mediate vesicular trafficking and to uncover cargo clients of specific cellular factors.
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