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Navratna V, Kumar A, Rana JK, Mosalaganti S. Structure of the human systemic RNAi defective transmembrane protein 1 (hSIDT1) reveals the conformational flexibility of its lipid binding domain. Life Sci Alliance 2024; 7:e202402624. [PMID: 38925866 PMCID: PMC11208740 DOI: 10.26508/lsa.202402624] [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: 01/26/2024] [Revised: 06/10/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024] Open
Abstract
In Caenorhabditis elegans, inter-cellular transport of the small non-coding RNA causing systemic RNAi is mediated by the transmembrane protein SID1, encoded by the sid1 gene in the systemic RNAi defective (sid) loci. SID1 shares structural and sequence similarity with cholesterol uptake protein 1 (CHUP1) and is classified as a member of the ChUP family. Although systemic RNAi is not an evolutionarily conserved process, the sid gene products are found across the animal kingdom, suggesting the existence of other novel gene regulatory mechanisms mediated by small non-coding RNAs. Human homologs of sid gene products-hSIDT1 and hSIDT2-mediate contact-dependent lipophilic small non-coding dsRNA transport. Here, we report the structure of recombinant human SIDT1. We find that the extra-cytosolic domain of hSIDT1 adopts a double jelly roll fold, and the transmembrane domain exists as two modules-a flexible lipid binding domain and a rigid transmembrane domain core. Our structural analyses provide insights into the inherent conformational dynamics within the lipid binding domain in ChUP family members.
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Affiliation(s)
- Vikas Navratna
- https://ror.org/00jmfr291 Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- https://ror.org/00jmfr291 Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | | | - Jaimin K Rana
- https://ror.org/00jmfr291 Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- https://ror.org/00jmfr291 Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Shyamal Mosalaganti
- https://ror.org/00jmfr291 Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- https://ror.org/00jmfr291 Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- https://ror.org/00jmfr291 Department of Biophysics, College of Literature, Science and the Arts, University of Michigan, Ann Arbor, MI, USA
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2
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Zhang J, Zhan C, Fan J, Wu D, Zhang R, Wu D, Chen X, Lu Y, Li M, Lin M, Gong J, Jiang D. Structural insights into double-stranded RNA recognition and transport by SID-1. Nat Struct Mol Biol 2024; 31:1095-1104. [PMID: 38664565 DOI: 10.1038/s41594-024-01276-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 03/14/2024] [Indexed: 07/20/2024]
Abstract
RNA uptake by cells is critical for RNA-mediated gene interference (RNAi) and RNA-based therapeutics. In Caenorhabditis elegans, RNAi is systemic as a result of SID-1-mediated double-stranded RNA (dsRNA) across cells. Despite the functional importance, the underlying mechanisms of dsRNA internalization by SID-1 remain elusive. Here we describe cryogenic electron microscopy structures of SID-1, SID-1-dsRNA complex and human SID-1 homologs SIDT1 and SIDT2, elucidating the structural basis of dsRNA recognition and import by SID-1. The homodimeric SID-1 homologs share conserved architecture, but only SID-1 possesses the molecular determinants within its extracellular domains for distinguishing dsRNA from single-stranded RNA and DNA. We show that the removal of the long intracellular loop between transmembrane helix 1 and 2 attenuates dsRNA uptake and systemic RNAi in vivo, suggesting a possible endocytic mechanism of SID-1-mediated dsRNA internalization. Our study provides mechanistic insights into dsRNA internalization by SID-1, which may facilitate the development of dsRNA applications based on SID-1.
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Affiliation(s)
- Jiangtao Zhang
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Chunhua Zhan
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Junping Fan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, China
| | - Dian Wu
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Ruixue Zhang
- Key Laboratory of Agricultural Microbiome (MARA), Biotechnology Research Institute, Chinese Academy Agricultural Sciences, Beijing, China
| | - Di Wu
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xinyao Chen
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ying Lu
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ming Li
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Min Lin
- Food Laboratory of Zhongyuan, College of Agriculture, Henan University, Kaifeng, Henan, China
| | - Jianke Gong
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Daohua Jiang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
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3
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Navratna V, Kumar A, Rana JK, Mosalaganti S. Structure of the human systemic RNAi defective transmembrane protein 1 (hSIDT1) reveals the conformational flexibility of its lipid binding domain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.21.572875. [PMID: 38187772 PMCID: PMC10769365 DOI: 10.1101/2023.12.21.572875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
In C. elegans, inter-cellular transport of the small non-coding RNA causing systemic RNA interference (RNAi) is mediated by the transmembrane protein SID1, encoded by the sid1 gene in the systemic RNA interference-defective (sid) loci. SID1 shares structural and sequence similarity with cholesterol uptake protein 1 (CHUP1) and is classified as a member of the cholesterol uptake family (ChUP). Although systemic RNAi is not an evolutionarily conserved process, the sid gene products are found across the animal kingdom, suggesting the existence of other novel gene regulatory mechanisms mediated by small non-coding RNAs. Human homologs of sid gene products - hSIDT1 and hSIDT2 - mediate contact-dependent lipophilic small non-coding dsRNA transport. Here, we report the structure of recombinant human SIDT1. We find that the extra-cytosolic domain (ECD) of hSIDT1 adopts a double jelly roll fold, and the transmembrane domain (TMD) exists as two modules - a flexible lipid binding domain (LBD) and a rigid TMD core. Our structural analyses provide insights into the inherent conformational dynamics within the lipid binding domain in cholesterol uptake (ChUP) family members.
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Affiliation(s)
- Vikas Navratna
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109, United States
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, 48109, United States
| | - Arvind Kumar
- Thermo Fisher Scientific, Waltham, Massachusetts, 02451, United States
| | - Jaimin K. Rana
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109, United States
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, 48109, United States
| | - Shyamal Mosalaganti
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109, United States
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, 48109, United States
- Department of Biophysics, College of Literature, Science and the Arts, University of Michigan, Ann Arbor, Michigan, 48109, United States
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4
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Song Y, Gu J, You J, Tao Y, Zhang Y, Wang L, Gao J. The functions of SID1 transmembrane family, member 2 (Sidt2). FEBS J 2023; 290:4626-4637. [PMID: 36176242 DOI: 10.1111/febs.16641] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 09/02/2022] [Accepted: 09/28/2022] [Indexed: 11/30/2022]
Abstract
The SID1 transmembrane family, member 2, namely, Sidt2, is a highly glycosylated multichannel lysosomal transmembrane protein, but its specific physiological function remains unknown. Lysosomal membrane proteins are very important for the executive functioning of lysosomes. As an important part of the lysosomal membrane, Sidt2 can maintain the normal morphology of lysosomes and help stabilize them from the acidic pH environment within. As a receptor/transporter, it binds and transports nucleic acids and mediates the uptake and degradation of RNA and DNA by the lysosome. During glucose metabolism, deletion of Sidt2 can cause an increase in fasting blood glucose and the impairment of grape tolerance, which is closely related to the secretion of insulin. During lipid metabolism, the loss of Sidt2 can cause hepatic steatosis and lipid metabolism disorders and can also play a role in signal regulation and transport. Here, we review the function of the lysosomal membrane protein Sidt2, and focus on its role in glucose and lipid metabolism, autophagy and nucleotide (DNA/RNA) transport.
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Affiliation(s)
- Yingying Song
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Department of Endocrinology and Genetic Metabolism, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research, Wannan Medical College, Wuhu, China
| | - Jing Gu
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Department of Endocrinology and Genetic Metabolism, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research, Wannan Medical College, Wuhu, China
| | - Jingya You
- Anhui Province Key Laboratory of Biological Macro-Molecules Research, Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Yiyang Tao
- Anhui Province Key Laboratory of Biological Macro-Molecules Research, Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Yao Zhang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research, Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Lizhuo Wang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research, Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Jialin Gao
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Department of Endocrinology and Genetic Metabolism, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research, Wannan Medical College, Wuhu, China
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Chai P, Lebedenko CG, Flynn RA. RNA Crossing Membranes: Systems and Mechanisms Contextualizing Extracellular RNA and Cell Surface GlycoRNAs. Annu Rev Genomics Hum Genet 2023; 24:85-107. [PMID: 37068783 DOI: 10.1146/annurev-genom-101722-101224] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
The subcellular localization of a biopolymer often informs its function. RNA is traditionally confined to the cytosolic and nuclear spaces, where it plays critical and conserved roles across nearly all biochemical processes. Our recent observation of cell surface glycoRNAs may further explain the extracellular role of RNA. While cellular membranes are efficient gatekeepers of charged polymers such as RNAs, a large body of research has demonstrated the accumulation of specific RNA species outside of the cell, termed extracellular RNAs (exRNAs). Across various species and forms of life, protein pores have evolved to transport RNA across membranes, thus providing a mechanistic path for exRNAs to achieve their extracellular topology. Here, we review types of exRNAs and the pores capable of RNA transport to provide a logical and testable path toward understanding the biogenesis and regulation of cell surface glycoRNAs.
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Affiliation(s)
- Peiyuan Chai
- Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Charlotta G Lebedenko
- Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Ryan A Flynn
- Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
- Harvard Stem Cell Institute, Harvard University, Cambridge, Massachusetts, USA
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Qian D, Cong Y, Wang R, Chen Q, Yan C, Gong D. Structural insight into the human SID1 transmembrane family member 2 reveals its lipid hydrolytic activity. Nat Commun 2023; 14:3568. [PMID: 37322007 PMCID: PMC10272179 DOI: 10.1038/s41467-023-39335-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 06/08/2023] [Indexed: 06/17/2023] Open
Abstract
The systemic RNAi-defective (SID) transmembrane family member 2 (SIDT2) is a putative nucleic acid channel or transporter that plays essential roles in nucleic acid transport and lipid metabolism. Here, we report the cryo-electron microscopy (EM) structures of human SIDT2, which forms a tightly packed dimer with extensive interactions mediated by two previously uncharacterized extracellular/luminal β-strand-rich domains and the unique transmembrane domain (TMD). The TMD of each SIDT2 protomer contains eleven transmembrane helices (TMs), and no discernible nucleic acid conduction pathway has been identified within the TMD, suggesting that it may act as a transporter. Intriguingly, TM3-6 and TM9-11 form a large cavity with a putative catalytic zinc atom coordinated by three conserved histidine residues and one aspartate residue lying approximately 6 Å from the extracellular/luminal surface of the membrane. Notably, SIDT2 can hydrolyze C18 ceramide into sphingosine and fatty acid with a slow rate. The information presented advances the understanding of the structure-function relationships in the SID1 family proteins.
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Affiliation(s)
- Dandan Qian
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin, 300350, China
| | - Ye Cong
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100084, China
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China
| | - Runhao Wang
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin, 300350, China
| | - Quan Chen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin, 300350, China.
| | - Chuangye Yan
- School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing, 100084, China.
- Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100084, China.
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China.
| | - Deshun Gong
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin, 300350, China.
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Gu J, Geng M, Qi M, Wang L, Zhang Y, Gao J. The role of lysosomal membrane proteins in glucose and lipid metabolism. FASEB J 2021; 35:e21848. [PMID: 34582051 DOI: 10.1096/fj.202002602r] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/11/2021] [Accepted: 07/26/2021] [Indexed: 11/11/2022]
Abstract
Lysosomes have long been regarded as the "garbage dump" of the cell. More recently, however, researchers have revealed novel roles for lysosomal membranes in autophagy, ion transport, nutrition sensing, and membrane fusion and repair. With active research into lysosomal membrane proteins (LMP), increasing evidence has become available showing that LMPs are inextricably linked to glucose and lipid metabolism, and this relationship represents mutual influence and regulation. In this review, we summarize the roles of LMPs in relation to glucose and lipid metabolism, and describe their roles in glucose transport, glycolysis, cholesterol transport, and lipophagy. The role of transport proteins can be traced back to the original discoveries of GLUT8, NPC1, and NPC2, which were all found to have significant roles in the pathways involved in glucose and lipid metabolism. CLC-5 and SIDT2-knockout animals show serious phenotypic disorders of metabolism, and V-ATPase and LAMP-2 have been found to interact with proteins related to glucose and lipid metabolism. These findings all emphasize the critical role of LMPs in glycolipid metabolism and help to strengthen our understanding of the independent and close relationship between LMPs and glycolipid metabolism.
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Affiliation(s)
- Jing Gu
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
| | - Mengya Geng
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Mengxiang Qi
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Lizhuo Wang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Yao Zhang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Jialin Gao
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
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León-Mimila P, Villamil-Ramírez H, Macías-Kauffer LR, Jacobo-Albavera L, López-Contreras BE, Posadas-Sánchez R, Posadas-Romero C, Romero-Hidalgo S, Morán-Ramos S, Domínguez-Pérez M, Olivares-Arevalo M, López-Montoya P, Nieto-Guerra R, Acuña-Alonzo V, Macín-Pérez G, Barquera-Lozano R, Del-Río-Navarro BE, González-González I, Campos-Pérez F, Gómez-Pérez F, Valdés VJ, Sampieri A, Reyes-García JG, Carrasco-Portugal MDC, Flores-Murrieta FJ, Aguilar-Salinas CA, Vargas-Alarcón G, Shih D, Meikle PJ, Calkin AC, Drew BG, Vaca L, Lusis AJ, Huertas-Vazquez A, Villarreal-Molina T, Canizales-Quinteros S. Genome-Wide Association Study Identifies a Functional SIDT2 Variant Associated With HDL-C (High-Density Lipoprotein Cholesterol) Levels and Premature Coronary Artery Disease. Arterioscler Thromb Vasc Biol 2021; 41:2494-2508. [PMID: 34233476 PMCID: PMC8664085 DOI: 10.1161/atvbaha.120.315391] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective Low HDL-C (high-density lipoprotein cholesterol) is the most frequent dyslipidemia in Mexicans, but few studies have examined the underlying genetic basis. Our purpose was to identify genetic variants associated with HDL-C levels and cardiovascular risk in the Mexican population. Approach and Results A genome-wide association studies for HDL-C levels in 2335 Mexicans, identified four loci associated with genome-wide significance: CETP, ABCA1, LIPC, and SIDT2. The SIDT2 missense Val636Ile variant was associated with HDL-C levels and was replicated in 3 independent cohorts (P=5.9×10−18 in the conjoint analysis). The SIDT2/Val636Ile variant is more frequent in Native American and derived populations than in other ethnic groups. This variant was also associated with increased ApoA1 and glycerophospholipid serum levels, decreased LDL-C (low-density lipoprotein cholesterol) and ApoB levels, and a lower risk of premature CAD. Because SIDT2 was previously identified as a protein involved in sterol transport, we tested whether the SIDT2/Ile636 protein affected this function using an in vitro site-directed mutagenesis approach. The SIDT2/Ile636 protein showed increased uptake of the cholesterol analog dehydroergosterol, suggesting this variant affects function. Finally, liver transcriptome data from humans and the Hybrid Mouse Diversity Panel are consistent with the involvement of SIDT2 in lipid and lipoprotein metabolism. Conclusions This is the first genome-wide association study for HDL-C levels seeking associations with coronary artery disease in the Mexican population. Our findings provide new insight into the genetic architecture of HDL-C and highlight SIDT2 as a new player in cholesterol and lipoprotein metabolism in humans.
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Affiliation(s)
- Paola León-Mimila
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
| | - Hugo Villamil-Ramírez
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
| | - Luis R Macías-Kauffer
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
- Dirección de Planeación, Enseñanza e Investigación, Hospital Regional de Alta Especialidad de Ixtapaluca, Estado de México (L.R.M.-K.)
| | - Leonor Jacobo-Albavera
- Laboratorio de Enfermedades Cardiovasculares, INMEGEN, Mexico City (L.J.-A., M.D.-P., T.V.-M.)
| | - Blanca E López-Contreras
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
| | - Rosalinda Posadas-Sánchez
- Departamento de Endocrinología, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City (R.P.-S., C.P.-R.)
| | - Carlos Posadas-Romero
- Departamento de Endocrinología, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City (R.P.-S., C.P.-R.)
| | | | - Sofía Morán-Ramos
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
- Consejo Nacional de Ciencia y Tecnología (CONACyT), Mexico City (S.M.-R.)
| | - Mayra Domínguez-Pérez
- Laboratorio de Enfermedades Cardiovasculares, INMEGEN, Mexico City (L.J.-A., M.D.-P., T.V.-M.)
| | - Marisol Olivares-Arevalo
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
| | - Priscilla López-Montoya
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
| | - Roberto Nieto-Guerra
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
| | | | - Gastón Macín-Pérez
- Escuela Nacional de Antropología e Historia, Mexico City (V.A.-A., G.M.-P.)
| | | | | | | | | | - Francisco Gómez-Pérez
- Unidad de Investigación en Enfermedades Metabólicas and Departamento de Endocrinología y Metabolismo, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City (F.G.-P., C.A.A.-S.)
| | - Victor J Valdés
- Instituto de Fisiología Celular, UNAM, Mexico City (V.J.V., A.S., L.V.)
| | - Alicia Sampieri
- Instituto de Fisiología Celular, UNAM, Mexico City (V.J.V., A.S., L.V.)
| | - Juan G Reyes-García
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City (J.G.R.-G., F.J.F.-M.)
| | - Miriam Del C Carrasco-Portugal
- Unidad de Investigación en Farmacología, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City (M.C.-P., F.J.F.-M.)
| | - Francisco J Flores-Murrieta
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City (J.G.R.-G., F.J.F.-M.)
- Unidad de Investigación en Farmacología, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City (M.C.-P., F.J.F.-M.)
| | - Carlos A Aguilar-Salinas
- Unidad de Investigación en Enfermedades Metabólicas and Departamento de Endocrinología y Metabolismo, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City (F.G.-P., C.A.A.-S.)
- Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, N.L. Mexico (C.A.A.-S.)
| | - Gilberto Vargas-Alarcón
- Departamento de Biología Molecular, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City (G.V.-A.)
| | - Diana Shih
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles (D.S., A.J.L., A.H.-V.)
| | - Peter J Meikle
- Head Metabolomics Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia (P.J.M.)
| | - Anna C Calkin
- Baker Heart and Diabetes Institute, Melbourne, VIC, Australia (A.C.C., B.G.D.)
- Central Clinical School, Monash University, Melbourne, VIC, Australia (A.C.C., B.G.D.)
- Baker Department of Cardiometabolic Health, University of Melbourne, Parkville, VIC, Australia (A.C.C., B.G.D.)
| | - Brian G Drew
- Baker Heart and Diabetes Institute, Melbourne, VIC, Australia (A.C.C., B.G.D.)
- Central Clinical School, Monash University, Melbourne, VIC, Australia (A.C.C., B.G.D.)
- Baker Department of Cardiometabolic Health, University of Melbourne, Parkville, VIC, Australia (A.C.C., B.G.D.)
| | - Luis Vaca
- Instituto de Fisiología Celular, UNAM, Mexico City (V.J.V., A.S., L.V.)
| | - Aldons J Lusis
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles (D.S., A.J.L., A.H.-V.)
| | - Adriana Huertas-Vazquez
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles (D.S., A.J.L., A.H.-V.)
| | | | - Samuel Canizales-Quinteros
- Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México (UNAM)/Instituto Nacional de Medicina Genómica (INMEGEN), Mexico City (P.L.-M., H.V.-R., L.R.M.-K., B.E.L.-C., S.M.-R., M.O.-A., P.L.-M., R.N.-G., S.C.-Q.)
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9
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Germanos M, Gao A, Taper M, Yau B, Kebede MA. Inside the Insulin Secretory Granule. Metabolites 2021; 11:metabo11080515. [PMID: 34436456 PMCID: PMC8401130 DOI: 10.3390/metabo11080515] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 12/19/2022] Open
Abstract
The pancreatic β-cell is purpose-built for the production and secretion of insulin, the only hormone that can remove glucose from the bloodstream. Insulin is kept inside miniature membrane-bound storage compartments known as secretory granules (SGs), and these specialized organelles can readily fuse with the plasma membrane upon cellular stimulation to release insulin. Insulin is synthesized in the endoplasmic reticulum (ER) as a biologically inactive precursor, proinsulin, along with several other proteins that will also become members of the insulin SG. Their coordinated synthesis enables synchronized transit through the ER and Golgi apparatus for congregation at the trans-Golgi network, the initiating site of SG biogenesis. Here, proinsulin and its constituents enter the SG where conditions are optimized for proinsulin processing into insulin and subsequent insulin storage. A healthy β-cell is continually generating SGs to supply insulin in vast excess to what is secreted. Conversely, in type 2 diabetes (T2D), the inability of failing β-cells to secrete may be due to the limited biosynthesis of new insulin. Factors that drive the formation and maturation of SGs and thus the production of insulin are therefore critical for systemic glucose control. Here, we detail the formative hours of the insulin SG from the luminal perspective. We do this by mapping the journey of individual members of the SG as they contribute to its genesis.
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10
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Nguyen TA, Bieging-Rolett KT, Putoczki TL, Wicks IP, Attardi LD, Pang KC. SIDT2 RNA Transporter Promotes Lung and Gastrointestinal Tumor Development. iScience 2019; 20:14-24. [PMID: 31546103 PMCID: PMC6817685 DOI: 10.1016/j.isci.2019.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/20/2019] [Accepted: 09/05/2019] [Indexed: 02/07/2023] Open
Abstract
RNautophagy is a newly described type of selective autophagy whereby cellular RNAs are transported into lysosomes for degradation. This process involves the transmembrane protein SIDT2, which transports double-stranded RNA (dsRNA) across the endolysosomal membrane. We previously demonstrated that SIDT2 is a transcriptional target of p53, but its role in tumorigenesis, if any, is unclear. Unexpectedly, we show here that Sidt2−/− mice with concurrent oncogenic KrasG12D activation develop significantly fewer tumors than littermate controls in a mouse model of lung adenocarcinoma. Consistent with this observation, loss of SIDT2 also leads to enhanced survival and delayed tumor development in an Apcmin/+ mouse model of intestinal cancer. Within the intestine, Apcmin/+;Sidt2−/− mice display accumulation of dsRNA in association with increased phosphorylation of eIF2α and JNK as well as elevated rates of apoptosis. Taken together, our data demonstrate a role for SIDT2, and by extension RNautophagy, in promoting tumor development. Loss of the SIDT2 double-stranded RNA (dsRNA) transporter leads to accumulation of dsRNA in tissues is associated with increased apoptosis reduces tumor burden in mouse models of lung adenocarcinoma and intestinal cancer
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Affiliation(s)
- Tan A Nguyen
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Kathryn T Bieging-Rolett
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Tracy L Putoczki
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Ian P Wicks
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Laura D Attardi
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Ken C Pang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Murdoch Children's Research Institute, Parkville, VIC, Australia; Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia; Department of Psychiatry, University of Melbourne, Parkville, VIC, Australia.
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11
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Liu H, Jiang W, Chen X, Chang G, Zhao L, Li X, Zhang H. Skeletal muscle-specific Sidt2 knockout in mice induced muscular dystrophy-like phenotype. Metabolism 2018; 85:259-270. [PMID: 29752955 DOI: 10.1016/j.metabol.2018.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 04/21/2018] [Accepted: 05/07/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND Sidt2 is an integral lysosomal membrane protein. Previously, we generated a Sidt2 global knockout mouse and found impaired insulin secretion, along with skeletal muscle pathology. METHODS A mouse model with a muscle-specific knockout of the Sidt2 gene (Sidt2f/fCre) had been generated, to which extensive morphologic study as well as functional study was applied to investigate the direct role of Sidt2 on skeletal muscle tissue in vivo. Secondly, the autophagy-lysosomal pathway was examined by Western blot and immunostaining. Additionally, RNA expression changes in Sidt2f/fCre mice were analyzed by genechip. RESULTS Sidt2 deficiency in skeletal muscle results in pathognomonic hallmarks of muscular dystrophy, including muscle mass decrease, muscle weakness, fibrosis, central nucleation, fiber regeneration, mildly elevated serum creatine kinase, and dramatically elevated sarcolipin mRNA. Along with accumulation of autophagolysomes, LC3-II, adaptor protein p62, ubiquitinated aggregates, and Lamp2-positive vacuoles were increased significantly in Sidt2f/fCre skeletal muscle fibers. However, only lysosomal-related genes were upregulated, while the genes upstream of the autophagy pathway were unchanged. Simultaneously, the proteasome chymotryptic activity and the lysosomal soluble enzyme activity were unimpaired, which largely excluded the possibility of proteasome chymotryptic activity defect and the lysosomal soluble enzyme defect leading to ubiquitinated aggregates accumulation. CONCLUSION We concluded that Sidt2 deficiency leads to muscular dystrophy-like phenotype in mice and Sidt2 plays a critical role in the late stage of autophagy.
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Affiliation(s)
- Huan Liu
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenjun Jiang
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xueru Chen
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guoying Chang
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lei Zhao
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China
| | - Xihua Li
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China.
| | - Huiwen Zhang
- Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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12
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Sugden LA, Atkinson EG, Fischer AP, Rong S, Henn BM, Ramachandran S. Localization of adaptive variants in human genomes using averaged one-dependence estimation. Nat Commun 2018; 9:703. [PMID: 29459739 PMCID: PMC5818606 DOI: 10.1038/s41467-018-03100-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 01/19/2018] [Indexed: 12/19/2022] Open
Abstract
Statistical methods for identifying adaptive mutations from population genetic data face several obstacles: assessing the significance of genomic outliers, integrating correlated measures of selection into one analytic framework, and distinguishing adaptive variants from hitchhiking neutral variants. Here, we introduce SWIF(r), a probabilistic method that detects selective sweeps by learning the distributions of multiple selection statistics under different evolutionary scenarios and calculating the posterior probability of a sweep at each genomic site. SWIF(r) is trained using simulations from a user-specified demographic model and explicitly models the joint distributions of selection statistics, thereby increasing its power to both identify regions undergoing sweeps and localize adaptive mutations. Using array and exome data from 45 ‡Khomani San hunter-gatherers of southern Africa, we identify an enrichment of adaptive signals in genes associated with metabolism and obesity. SWIF(r) provides a transparent probabilistic framework for localizing beneficial mutations that is extensible to a variety of evolutionary scenarios.
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Affiliation(s)
- Lauren Alpert Sugden
- Center for Computational Molecular Biology, Brown University, Providence, RI, 02912, USA.
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA.
| | - Elizabeth G Atkinson
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Annie P Fischer
- Division of Applied Mathematics, Brown University, Providence, RI, 02912, USA
| | - Stephen Rong
- Center for Computational Molecular Biology, Brown University, Providence, RI, 02912, USA
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, 02912, USA
| | - Brenna M Henn
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Sohini Ramachandran
- Center for Computational Molecular Biology, Brown University, Providence, RI, 02912, USA.
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA.
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13
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Chen X, Gu X, Zhang H. Sidt2 regulates hepatocellular lipid metabolism through autophagy. J Lipid Res 2018; 59:404-415. [PMID: 29363559 DOI: 10.1194/jlr.m073817] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/23/2018] [Indexed: 12/22/2022] Open
Abstract
SID1 transmembrane family member 2 (Sidt2) is an integral lysosomal membrane protein. To investigate its explicit function, we generated a global Sidt2 knockout mouse model (Sidt2-/-). Compared with the littermate controls, Sidt2-/- mice exhibited a remarkable accumulation of lipid droplets in liver. First, it was observed that food consumption, hepatocyte fatty acid uptake and de novo lipogenesis, hepatocyte lipolysis, and TG secretion in the form of very low density lipoprotein were comparable between Sidt2-/- and WT mice. However, the hepatic β-oxidation of fatty acids decreased significantly as revealed by a low level of serum β-hydroxybutyrate in the Sidt2-/- mice along with normal mRNA expression of genes involved in fatty acid oxidation. In addition, the classical autophagy pathway marker proteins, p62 and LC3-II, increased in liver, along with compromised autophagic flux in primary hepatocytes, indicating a block of autophagosome maturation due to Sidt2 deficiency, which was also supported by electron microscopy image analysis both in livers and in primary hepatocytes from Sidt2-/- mice. It was concluded that Sidt2 plays an important role in mouse hepatic lipid homeostasis by regulating autophagy at the terminal stage.
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Affiliation(s)
- Xueru Chen
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xuefan Gu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Huiwen Zhang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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14
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Klugbauer N. New clues on Sidt2 being a cation conducting protein in lysosomal membranes. FEBS Lett 2017; 591:3-4. [PMID: 28066891 DOI: 10.1002/1873-3468.12541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Norbert Klugbauer
- Medizinische Fakultät, Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Freiburg, Germany
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15
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Beck A, Fecher-Trost C, Wolske K, Philipp SE, Flockerzi V, Wissenbach U. Identification of Sidt2 as a lysosomal cation-conducting protein. FEBS Lett 2017; 591:76-87. [PMID: 27987306 DOI: 10.1002/1873-3468.12528] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 11/25/2016] [Accepted: 12/01/2016] [Indexed: 12/18/2022]
Abstract
A screen to identify lysosomal-expressed ion channels led to the discovery of the human Sidt2 protein. Sidt2 is expressed within lysosomal organelles but as a result of heterologous overexpression the protein is also detectable within the plasma membrane of human embryonic kidney cells. The overexpressed protein leads to cell depolarization upon sodium addition. Accordingly in whole-cell patch clamp experiments a spontaneous noninactivating monovalent cation current can be detected in Sidt2-overexpressing cells. Strong overexpression of Sidt2 in HEK293 cells is attended by a significant reduction/loss of detectable lysosomes, indicating that the overexpressed protein leads to lysosomal dysfunction, a hallmark of Alzheimer's disease. Sidt2 is located on chromosome 11q23, a locus repeatedly found by chromosomal mapping of Alzheimer's disease-related genes.
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Affiliation(s)
- Andreas Beck
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Germany
| | - Claudia Fecher-Trost
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Germany
| | - Karin Wolske
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Germany
| | - Stephan E Philipp
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Germany
| | - Veit Flockerzi
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Germany
| | - Ulrich Wissenbach
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Germany
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16
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Gao J, Zhang Y, Yu C, Tan F, Wang L. Spontaneous nonalcoholic fatty liver disease and ER stress in Sidt2 deficiency mice. Biochem Biophys Res Commun 2016; 476:326-332. [PMID: 27233614 DOI: 10.1016/j.bbrc.2016.05.122] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 05/24/2016] [Indexed: 12/12/2022]
Abstract
Sidt2 is a newly discovered lysosomal membrane protein that is closely related to glucose metabolism. In the present study, we found that Sidt2 is also closely related to lipid metabolism. Gradual increases in serum triglyceride (TG) and free fatty acid, as well as elevated aspartate transaminase and alanine transaminase levels were observed in Sidt2(-/-) mice fed a normal diet from the age of 3 months, suggesting the presence of lipid metabolism disorders and impaired liver function in these mice. In the liver slices of 6-month-old Sidt2(-/-) mice, there were obvious fat degeneration and inflammatory changes. Almost all of the liver cells demonstrated different levels of lipid droplet accumulation and cell swelling, and some of the cells demonstrated balloon-like changes. Infiltration of inflammatory cells was observed in the portal area and hepatic lobule. Electron microscopy showed that macrophages tended to be attached to the endothelial cells, and a large number of lipid droplets were present in the liver cells. Oil red O staining showed that there were significantly increased number of deep straining particles in the liver cells of Sidt2(-/-) mice, and the TG content in liver tissue was also significantly increased. Detection of key genes and proteins related to fat synthesis showed that mRNA and protein levels of the SREBP1c in the liver of Sidt2(-/-) mice were significantly elevated, and the downstream genes acetyl-CoA carboxylase, fatty acid synthase, and mitochondrial glycerol 3-phosphate acyltransferase were significantly upregulated. In addition, there was severe endoplasmic reticulum stress (ERS) in the liver of Sidt2(-/-) mice, which had significantly increased levels of markers specific for unfolded protein response activation, Grp78 and CHOP, as well as significant elevation of downstream p-PERK, p-eIF2a, p-IRE1a, along with ER damage. These results suggest that Sidt2(-/-) mice had spontaneous nonalcoholic fatty liver disease (NAFLD) accompanied by ERS. In summary, as a lysosomal membrane protein, Sidt2 plays an important role in the pathogenesis of NAFLD, and ERS may mediate the occurrence and development of this disease in Sdit2 deficiency mice.
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Affiliation(s)
- Jialin Gao
- Department of Endocrinology and Genetic Metabolism, Yijishan Hospital of Wannan Medical College, Wuhu, 241002, China; Anhui Province Key Laboratory of Biological Macro-molecules Research, Wannan Medical College, Wuhu, 241001, China
| | - Yao Zhang
- Anhui Province Key Laboratory of Biological Macro-molecules Research, Wannan Medical College, Wuhu, 241001, China; Department of Biochemistry and Molecular Biology, Wannan Medical Collage, Wuhu, 241002, China
| | - Cui Yu
- Department of Endocrinology and Genetic Metabolism, Yijishan Hospital of Wannan Medical College, Wuhu, 241002, China; Anhui Province Key Laboratory of Biological Macro-molecules Research, Wannan Medical College, Wuhu, 241001, China
| | - Fengbiao Tan
- Anhui Province Key Laboratory of Biological Macro-molecules Research, Wannan Medical College, Wuhu, 241001, China; Department of Biochemistry and Molecular Biology, Wannan Medical Collage, Wuhu, 241002, China
| | - Lizhuo Wang
- Anhui Province Key Laboratory of Biological Macro-molecules Research, Wannan Medical College, Wuhu, 241001, China; Department of Biochemistry and Molecular Biology, Wannan Medical Collage, Wuhu, 241002, China.
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