Expression and localisation of synaptotagmin isoforms in endocrine beta-cells: their function in insulin exocytosis

Article Article scientifique Article Expression and localisation of synaptotagmin isoforms in endocrine beta-cells: their function in insulin exocytosis eng 2001 author Gut A author Kiraly-Borri Catherine Eva 36026 author Fukuda M author Mikoshiba K author Wollheim Claes 25195 author Lang Jochen 24567 1709-1716 11309201 0021-9533 Exocytosis of insulin containing Large Dense Core Vesicles (LDCVs) from pancreatic beta-cells and derived cell lines is mainly controlled by Ca(2+). Several lines of evidence have demonstrated a role of the Ca(2+)- and phospholipid-binding protein synaptotagmin (syt) in this event. Synaptotagmins form a large protein family with distinct affinities for Ca(2+) determined by their two C(2) domains (C(2)A/B). Except for the well-characterized isoforms I and II, their role is still unclear. We have used here insulin-secreting cells as a model system for LDCV exocytosis to gain insight into the function of synaptotagmins. Immunocytochemical analysis revealed that of the candidate Ca(2+) sensors in LDCV exocytosis, syt III was not expressed in primary beta-cells, whereas syt IV was only found adjacent to the TGN. However, syt V-VIII isoforms were expressed at different levels in various insulin-secreting cells and in pancreatic islet preparations. In streptolysin-O permeabilized primary beta-cells the introduction of recombinant peptides (100 nM) corresponding to the C(2) domains of syt V, VII and VIII, but not of syt III, IV or VI, inhibited Ca(2+)-evoked insulin exocytosis by 30% without altering GTP gamma S-induced release. Our observations demonstrate that syt III and IV are not involved in the exocytosis of LDCVs from primary beta-cells whereas V, VII and VIII may mediate Ca(2+)-regulation of exocytosis. Animals Calcium-Binding Proteins Cell Line Exocytosis Insulin/metabolism Islets of Langerhans/cytology/metabolism Male Membrane Glycoproteins/metabolism Nerve Tissue Proteins/metabolism Protein Isoforms/metabolism Rats Rats, Wistar Synaptotagmins Dewey 616 56 Département de médecine 221 false Journal of cell science 114 Pt 9 151ee75d-b171-4d98-9efe-a82098e7b591 Article (Published version) Public J Cell Sci-2001-Gut-1709-16.pdf 356891 application/pdf openAccess Faculté de médecine / Section de médecine clinique / Département de médecine

Title	Published in	Access level	OA Policy	Year	Views	Downloads

Expression and localisation of synaptotagmin isoforms in endocrine beta-cells: their function in insulin exocytosis	Journal of cell science			2001	533	163

Archive ouverte UNIGE

Kiraly-Borri, Catherine Eva