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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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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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Yang T, Xiao H, Chen X, Zheng L, Guo H, Wang J, Jiang X, Zhang CY, Yang F, Ji X. Characterization of N-glycosylation and its functional role in SIDT1-Mediated RNA uptake. J Biol Chem 2024; 300:105654. [PMID: 38237680 PMCID: PMC10850970 DOI: 10.1016/j.jbc.2024.105654] [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: 11/17/2023] [Revised: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 02/08/2024] Open
Abstract
The mammalian SID-1 transmembrane family members, SIDT1 and SIDT2, are multipass transmembrane proteins that mediate the cellular uptake and intracellular trafficking of nucleic acids, playing important roles in the immune response and tumorigenesis. Previous work has suggested that human SIDT1 and SIDT2 are N-glycosylated, but the precise site-specific N-glycosylation information and its functional contribution remain unclear. In this study, we use high-resolution liquid chromatography tandem mass spectrometry to comprehensively map the N-glycosites and quantify the N-glycosylation profiles of SIDT1 and SIDT2. Further molecular mechanistic probing elucidates the essential role of N-linked glycans in regulating cell surface expression, RNA binding, protein stability, and RNA uptake of SIDT1. Our results provide crucial information about the potential functional impact of N-glycosylation in the regulation of SIDT1-mediated RNA uptake and provide insights into the molecular mechanisms of this promising nucleic acid delivery system with potential implications for therapeutic applications.
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Affiliation(s)
- Tingting Yang
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Haonan Xiao
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Xiulan Chen
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Le Zheng
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Hangtian Guo
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Jiaqi Wang
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Xiaohong Jiang
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Chen-Yu Zhang
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China; Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing, Jiangsu, China.
| | - Fuquan Yang
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Xiaoyun Ji
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China; Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing, Jiangsu, China; Institute of Artificial Intelligence Biomedicine, Nanjing University, Nanjing, Jiangsu, China; Engineering Research Center of Protein and Peptide Medicine, Ministry of Education, Nanjing, Jiangsu, 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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Gaeta AL, Nourse JB, Willicott K, McKay LE, Keogh CM, Peter K, Russell SN, Hamamichi S, Berkowitz LA, Caldwell KA, Caldwell GA. Systemic RNA Interference Defective (SID) genes modulate dopaminergic neurodegeneration in C. elegans. PLoS Genet 2022; 18:e1010115. [PMID: 35984862 PMCID: PMC9432717 DOI: 10.1371/journal.pgen.1010115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 08/31/2022] [Accepted: 08/01/2022] [Indexed: 02/02/2023] Open
Abstract
The fine-tuning of gene expression is critical for all cellular processes; aberrations in this activity can lead to pathology, and conversely, resilience. As their role in coordinating organismal responses to both internal and external factors have increasingly come into focus, small non-coding RNAs have emerged as an essential component to disease etiology. Using Systemic RNA interference Defective (SID) mutants of the nematode Caenorhabditis elegans, deficient in gene silencing, we examined the potential consequences of dysfunctional epigenomic regulation in the context of Parkinson's disease (PD). Specifically, the loss of either the sid-1 or sid-3 genes, which encode a dsRNA transporter and an endocytic regulatory non-receptor tyrosine kinase, respectively, conferred neuroprotection to dopaminergic (DA) neurons in an established transgenic C. elegans strain wherein overexpression of human α-synuclein (α-syn) from a chromosomally integrated multicopy transgene causes neurodegeneration. We further show that knockout of a specific microRNA, mir-2, attenuates α-syn neurotoxicity; suggesting that the native targets of mir-2-dependent gene silencing represent putative neuroprotective modulators. In support of this, we demonstrated that RNAi knockdown of multiple mir-2 targets enhanced α-syn-induced DA neurodegeneration. Moreover, we demonstrate that mir-2 overexpression originating in the intestine can induce neurodegeneration of DA neurons, an effect that was reversed by pharmacological inhibition of SID-3 activity. Interestingly, sid-1 mutants retained mir-2-induced enhancement of neurodegeneration. Transcriptomic analysis of α-syn animals with and without a sid-1 mutation revealed 27 differentially expressed genes with human orthologs related to a variety of diseases, including PD. Among these was pgp-8, encoding a P-glycoprotein-related ABC transporter. Notably, sid-1; pgp-8 double mutants abolished the neurodegeneration resulting from intestinal mir-2 overexpression. This research positions known regulators of small RNA-dependent gene silencing within a framework that facilitates mechanistic evaluation of epigenetic responses to exogenous and endogenous factors influencing DA neurodegeneration, revealing a path toward new targets for therapeutic intervention of PD.
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Affiliation(s)
- Anthony L. Gaeta
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - J. Brucker Nourse
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Karolina Willicott
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Luke E. McKay
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Candice M. Keogh
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Kylie Peter
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Shannon N. Russell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Shusei Hamamichi
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Laura A. Berkowitz
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Kim A. Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
- Center for Convergent Bioscience and Medicine, The University of Alabama, Tuscaloosa, Alabama, United States of America
- Alabama Research Institute on Aging, The University of Alabama, Tuscaloosa, Alabama, United States of America
- Departments of Neurology and Neurobiology, Center for Neurodegeneration and Experimental Therapeutics, Nathan Shock Center of Excellence for Basic Research in the Biology of Aging, University of Alabama at Birmingham, Heersink School of Medicine, Birmingham, Alabama, United States of America
| | - Guy A. Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
- Center for Convergent Bioscience and Medicine, The University of Alabama, Tuscaloosa, Alabama, United States of America
- Departments of Neurology and Neurobiology, Center for Neurodegeneration and Experimental Therapeutics, Nathan Shock Center of Excellence for Basic Research in the Biology of Aging, University of Alabama at Birmingham, Heersink School of Medicine, Birmingham, Alabama, United States of America
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