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Kubota C, Torii R, Hosaka M, Takeuchi T, Gomi H, Torii S. Phogrin Regulates High-Fat Diet-Induced Compensatory Pancreatic β-Cell Growth by Switching Binding Partners. Nutrients 2024; 16:169. [PMID: 38201998 PMCID: PMC10780347 DOI: 10.3390/nu16010169] [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: 12/05/2023] [Revised: 12/26/2023] [Accepted: 12/29/2023] [Indexed: 01/12/2024] Open
Abstract
The receptor protein tyrosine phosphatase phogrin primarily localizes to hormone secretory granules in neuroendocrine cells. Concurrent with glucose-stimulated insulin secretion, phogrin translocates to pancreatic β-cell plasma membranes, where it interacts with insulin receptors (IRs) to stabilize insulin receptor substrate 2 (IRS2) that, in turn, contributes to glucose-responsive β-cell growth. Pancreatic β-cell development was not altered in β-cell-specific, phogrin-deficient mice, but the thymidine incorporation rate decreased in phogrin-deficient islets with a moderate reduction in IRS2 protein expression. In this study, we analyzed the β-cell response to high-fat diet stress and found that the compensatory expansion in β-cell mass was significantly suppressed in phogrin-deficient mice. Phogrin-IR interactions occurred only in high-fat diet murine islets and proliferating β-cell lines, whereas they were inhibited by the intercellular binding of surface phogrin under confluent cell culture conditions. Thus, phogrin could regulate glucose-stimulated compensatory β-cell growth by changing its binding partner from another β-cell phogrin to IR in the same β-cells.
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Affiliation(s)
- Chisato Kubota
- Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Gunma, Japan (T.T.)
- Department of Nutrition, Takasaki University of Health and Welfare, Takasaki 370-0033, Gunma, Japan
| | - Ryoko Torii
- Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Gunma, Japan (T.T.)
| | - Masahiro Hosaka
- Department of Biotechnology, Akita Prefectural University, Akita 010-0195, Akita, Japan;
| | - Toshiyuki Takeuchi
- Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Gunma, Japan (T.T.)
| | - Hiroshi Gomi
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, Fujisawa 252-0880, Kanagawa, Japan;
| | - Seiji Torii
- Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Gunma, Japan (T.T.)
- Center for Food Science and Wellness, Gunma University, Maebashi 371-8511, Gunma, Japan
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Toledo PL, Torkko JM, Müller A, Wegbrod C, Sönmez A, Solimena M, Ermácora MR. ICA512 RESP18 homology domain is a protein-condensing factor and insulin fibrillation inhibitor. J Biol Chem 2019; 294:8564-8576. [PMID: 30979722 DOI: 10.1074/jbc.ra119.007607] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/09/2019] [Indexed: 12/19/2022] Open
Abstract
Type 1 diabetes islet cell autoantigen 512 (ICA512/IA-2) is a tyrosine phosphatase-like intrinsic membrane protein involved in the biogenesis and turnover of insulin secretory granules (SGs) in pancreatic islet β-cells. Whereas its membrane-proximal and cytoplasmic domains have been functionally and structurally characterized, the role of the ICA512 N-terminal segment named "regulated endocrine-specific protein 18 homology domain" (RESP18HD), which encompasses residues 35-131, remains largely unknown. Here, we show that ICA512 RESP18HD residues 91-131 encode for an intrinsically disordered region (IDR), which in vitro acts as a condensing factor for the reversible aggregation of insulin and other β-cell proteins in a pH and Zn2+-regulated fashion. At variance with what has been shown for other granule cargoes with aggregating properties, the condensing activity of ICA512 RESP18HD is displayed at a pH close to neutral, i.e. in the pH range found in the early secretory pathway, whereas it is resolved at acidic pH and Zn2+ concentrations resembling those present in mature SGs. Moreover, we show that ICA512 RESP18HD residues 35-90, preceding the IDR, inhibit insulin fibrillation in vitro Finally, we found that glucose-stimulated secretion of RESP18HD upon exocytosis of SGs from insulinoma INS-1 cells is associated with cleavage of its IDR, conceivably to prevent its aggregation upon exposure to neutral pH in the extracellular milieu. Taken together, these findings point to ICA512 RESP18HD being a condensing factor for protein sorting and granulogenesis early in the secretory pathway and for prevention of amyloidogenesis.
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Affiliation(s)
- Pamela L Toledo
- Grupo de Biología Estructural y Biotecnología, Universidad Nacional de Quilmes, 1876 Bernal, Buenos Aires, Argentina; IMBICE, CONICET-CIC-Universidad Nacional de La Plata, B1906APO La Plata, Buenos Aires, Argentina
| | - Juha M Torkko
- Grupo de Biología Estructural y Biotecnología, Universidad Nacional de Quilmes, 1876 Bernal, Buenos Aires, Argentina; IMBICE, CONICET-CIC-Universidad Nacional de La Plata, B1906APO La Plata, Buenos Aires, Argentina; Department of Molecular Diabetology, University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
| | - Andreas Müller
- Department of Molecular Diabetology, University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
| | - Carolin Wegbrod
- Department of Molecular Diabetology, University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
| | - Anke Sönmez
- Department of Molecular Diabetology, University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
| | - Michele Solimena
- Department of Molecular Diabetology, University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, TU Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany; Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| | - Mario R Ermácora
- Grupo de Biología Estructural y Biotecnología, Universidad Nacional de Quilmes, 1876 Bernal, Buenos Aires, Argentina; IMBICE, CONICET-CIC-Universidad Nacional de La Plata, B1906APO La Plata, Buenos Aires, Argentina.
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Stability of proICA512/IA-2 and its targeting to insulin secretory granules require β4-sheet-mediated dimerization of its ectodomain in the endoplasmic reticulum. Mol Cell Biol 2015; 35:914-27. [PMID: 25561468 DOI: 10.1128/mcb.00994-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The type 1 diabetes autoantigen ICA512/IA-2/RPTPN is a receptor protein tyrosine phosphatase of the insulin secretory granules (SGs) which regulates the size of granule stores, possibly via cleavage/signaling of its cytosolic tail. The role of its extracellular region remains unknown. Structural studies indicated that β2- or β4-strands in the mature ectodomain (ME ICA512) form dimers in vitro. Here we show that ME ICA512 prompts proICA512 dimerization in the endoplasmic reticulum. Perturbation of ME ICA512 β2-strand N-glycosylation upon S508A replacement allows for proICA512 dimerization, O-glycosylation, targeting to granules, and conversion, which are instead precluded upon G553D replacement in the ME ICA512 β4-strand. S508A/G553D and N506A/G553D double mutants dimerize but remain in the endoplasmic reticulum. Removal of the N-terminal fragment (ICA512-NTF) preceding ME ICA512 allows an ICA512-ΔNTF G553D mutant to exit the endoplasmic reticulum, and ICA512-ΔNTF is constitutively delivered to the cell surface. The signal for SG sorting is located within the NTF RESP18 homology domain (RESP18-HD), whereas soluble NTF is retained in the endoplasmic reticulum. Hence, we propose that the ME ICA512 β2-strand fosters proICA512 dimerization until NTF prevents N506 glycosylation. Removal of this constraint allows for proICA512 β4-strand-induced dimerization, exit from the endoplasmic reticulum, O-glycosylation, and RESP18-HD-mediated targeting to granules.
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X-ray structure of the mature ectodomain of phogrin. ACTA ACUST UNITED AC 2014; 16:1-9. [PMID: 25421040 DOI: 10.1007/s10969-014-9191-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 11/19/2014] [Indexed: 10/24/2022]
Abstract
Phogrin/IA-2β and ICA512/IA-2 are two paralogs receptor-type protein-tyrosine phosphatases (RPTP) that localize in secretory granules of various neuroendocrine cells. In pancreatic islet β-cells, they participate in the regulation of insulin secretion, ensuring proper granulogenesis, and β-cell proliferation. The role of their cytoplasmic tail has been partially unveiled, while that of their luminal region remains unclear. To advance the understanding of its structure-function relationship, the X-ray structure of the mature ectodomain of phogrin (ME phogrin) at pH 7.4 and 4.6 has been solved at 1.95- and 2.01-Å resolution, respectively. Similarly to the ME of ICA512, ME phogrin adopts a ferredoxin-like fold: a sheet of four antiparallel β-strands packed against two α-helices. Sequence conservation among vertebrates, plants and insects suggests that the structural similarity extends to all the receptor family. Crystallized ME phogrin is monomeric, in agreement with solution studies but in striking contrast with the behavior of homodimeric ME ICA512. The structural details that may cause the quaternary structure differences are analyzed. The results provide a basis for building models of the overall orientation and oligomerization state of the receptor in biological membranes.
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Werk AN, Cascorbi I. Conference Scene: Pharmacogenomic highlights of the DGPT Annual Congress. Pharmacogenomics 2012; 13:997-9. [DOI: 10.2217/pgs.12.66] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This conference scene outlines a selection of sessions, which deals with the field of pharmacogenomics, held at the 78th Annual meeting of the German Society for Experimental and Clinical Pharmacology and Toxicology (DGPT), which took place from 19–22 March 2012 in Dresden, Germany. The DGPT is a registered society that represents the organization of three associations: the German Society for Pharmacology (dgp), the German Society for Clinical Pharmacology and Therapy (DGKliPha) and the German Society for Toxicology (gt). The conference represents a platform for intensive dialogues within and between the different disciplines covering basic science, the identification and understanding of new drug targets, the wide field of pharmaco- and toxico-genomics, drug regulation and toxicological risk assessment, as well as future advancements of new technologies.
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Affiliation(s)
- Anneke Nina Werk
- University Hospital Schleswig-Holstein, Institute for Experimental & Clinical Pharmacology, Arnold-Heller-Str. 3, Bldg. 30, 24105 Kiel, Germany
| | - Ingolf Cascorbi
- University Hospital Schleswig-Holstein, Institute for Experimental & Clinical Pharmacology, Arnold-Heller-Str. 3, Bldg. 30, 24105 Kiel, Germany
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