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Li X, Itani OA, Haataja L, Dumas KJ, Yang J, Cha J, Flibotte S, Shih HJ, Delaney CE, Xu J, Qi L, Arvan P, Liu M, Hu PJ. Requirement for translocon-associated protein (TRAP) α in insulin biogenesis. SCIENCE ADVANCES 2019; 5:eaax0292. [PMID: 31840061 PMCID: PMC6892615 DOI: 10.1126/sciadv.aax0292] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 10/07/2019] [Indexed: 05/26/2023]
Abstract
The mechanistic basis for the biogenesis of peptide hormones and growth factors is poorly understood. Here, we show that the conserved endoplasmic reticulum membrane translocon-associated protein α (TRAPα), also known as signal sequence receptor 1, plays a critical role in the biosynthesis of insulin. Genetic analysis in the nematode Caenorhabditis elegans and biochemical studies in pancreatic β cells reveal that TRAPα deletion impairs preproinsulin translocation while unexpectedly disrupting distal steps in insulin biogenesis including proinsulin processing and secretion. The association of common intronic single-nucleotide variants in the human TRAPα gene with susceptibility to type 2 diabetes and pancreatic β cell dysfunction suggests that impairment of preproinsulin translocation and proinsulin trafficking may contribute to the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Xin Li
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Omar A. Itani
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Leena Haataja
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Kathleen J. Dumas
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jing Yang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Jeeyeon Cha
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Stephane Flibotte
- Departments of Zoology and Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Hung-Jen Shih
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Colin E. Delaney
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jialu Xu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Ling Qi
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter Arvan
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Patrick J. Hu
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN, USA
- Division of Hematology and Oncology, Vanderbilt University Medical Center, Nashville, TN, USA
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Clustering of genetically defined allele classes in the Caenorhabditis elegans DAF-2 insulin/IGF-1 receptor. Genetics 2008; 178:931-46. [PMID: 18245374 PMCID: PMC2248335 DOI: 10.1534/genetics.107.070813] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The DAF-2 insulin/IGF-1 receptor regulates development, metabolism, and aging in the nematode Caenorhabditis elegans. However, complex differences among daf-2 alleles complicate analysis of this gene. We have employed epistasis analysis, transcript profile analysis, mutant sequence analysis, and homology modeling of mutant receptors to understand this complexity. We define an allelic series of nonconditional daf-2 mutants, including nonsense and deletion alleles, and a putative null allele, m65. The most severe daf-2 alleles show incomplete suppression by daf-18(0) and daf-16(0) and have a range of effects on early development. Among weaker daf-2 alleles there exist distinct mutant classes that differ in epistatic interactions with mutations in other genes. Mutant sequence analysis (including 11 newly sequenced alleles) reveals that class 1 mutant lesions lie only in certain extracellular regions of the receptor, while class 2 (pleiotropic) and nonconditional missense mutants have lesions only in the ligand-binding pocket of the receptor ectodomain or the tyrosine kinase domain. Effects of equivalent mutations on the human insulin receptor suggest an altered balance of intracellular signaling in class 2 alleles. These studies consolidate and extend our understanding of the complex genetics of daf-2 and its underlying molecular biology.
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Simonova M, Shtanko O, Sergeyev N, Weissleder R, Bogdanov A. Engineering of technetium-99m-binding artificial receptors for imaging gene expression. J Gene Med 2003; 5:1056-66. [PMID: 14661181 DOI: 10.1002/jgm.448] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Optimization of gene therapy protocols requires accurate and non-invasive quantification of vector delivery and gene expression. To facilitate non-invasive imaging of gene expression, we have genetically engineered 'artificial receptors', i.e. membrane proteins that bind (99m)Tc-oxotechnetate ((99m)TcOT) via transchelation from a complex with glucoheptonate. The latter is a component of a widely used clinical imaging kit. METHODS The engineered marker proteins were designed as type I and II membrane proteins and consisted of (1) an (99m)TcOT-binding domain, metallothionein (MT), and (2) a membrane-anchoring domain. Engineered constructs were used for transfection of COS-1 and 293 cells; the expression of mRNA was verified by RT-PCR. RESULTS Immunofluorescent analysis, cell fractionation and immunoblotting revealed expression of marker proteins on plasma membrane. Transfection of cells resulted in strong positive staining of plasma membrane with anti-His-tag antibodies. Scintigraphic imaging in vitro confirmed the ability of transfected cells to bind (99m)TcOT. The fraction of bound radioactivity reached a peak (3.53%) when 0.93 MBq (99m)TcOT was added to transfected COS-1 cells. The experiment-to-control signal ratio was equal to 32 at the same added dose. CONCLUSIONS (1) Both types of engineered 'artificial receptors' were expressed on the surface of eukaryotic cells; (2) marker proteins were functional in binding (99m)TcOT; and (3) type II membrane proteins were more efficient in binding (99m)TcOT than type I proteins. We anticipate that the developed approach could be useful for 'tagging' transfected cells with (99m)TcOT enabling imaging of tracking in vivo transduced cells or cell therapies.
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Affiliation(s)
- Maria Simonova
- Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital, Bldg. 149, 13th St., Charlestown, MA 02129, USA
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Maggi D, Biedi C, Segat D, Barbero D, Panetta D, Cordera R. IGF-I induces caveolin 1 tyrosine phosphorylation and translocation in the lipid rafts. Biochem Biophys Res Commun 2002; 295:1085-9. [PMID: 12135605 DOI: 10.1016/s0006-291x(02)00809-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Caveolin 1, a component of caveolae, regulates signalling pathways compartmentalization interacting with tyrosine kinase receptors and their substrates. The role of caveolin 1 in the Insulin Receptor (IR) signalling has been well investigated. On the contrary, the functional link between caveolin 1 and IGF-I Receptor (IGF-IR) remains largely unknown. Here we show that (1) IGF-IR colocalizes with caveolin 1 in the lipid rafts enriched fractions on plasmamembrane in R-IGF-IR(WT) cells, (2) IGF-I induces caveolin 1 phosphorylation at the level of tyrosine 14, (3) this effect is rapid and results in the translocation of caveolin 1 and in the formation of membrane patches on cell surface. These actions are IGF-I specific since we did not detect caveolin 1 redistribution in insulin stimulated R(-) cells overexpressing IRs.
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Affiliation(s)
- Davide Maggi
- Department of Endocrinology and Metabolism, University of Genoa, Genoa, Italy
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