%0 Journal Article %T The type 2 diabetes gene product STARD10 is a phosphoinositide binding protein that controls insulin secretory granule biogenesis %P 2020.03.25.007286 %* © 2020, Posted by Cold Spring Harbor Laboratory. This pre-print is available under a Creative Commons License (Attribution-NonCommercial-NoDerivs 4.0 International), CC BY-NC-ND 4.0, as described at http://creativecommons.org/licenses/by-nc-nd/4.0/ %U https://www.biorxiv.org/content/10.1101/2020.03.25.007286v2 %X
Objective: Risk alleles for type 2 diabetes at the STARD10 locus are associated with lowered STARD10 expression in the β-cell, impaired glucose-induced insulin secretion and decreased circulating proinsulin:insulin ratios. Although likely to serve as a mediator of intracellular lipid transfer, the identity of the transported lipids, and thus the pathways through which STARD10 regulates β-cell function, are not understood. The aim of this study was to identify the lipids transported and affected by STARD10 in the beta-cell and its effect on proinsulin processing and insulin granule biogenesis and maturation. Methods: We used isolated islets from mice deleted selectively in the beta-cell for Stard10 (βStarD10KO) and performed electron microscopy, pulse-chase, RNA sequencing and lipidomic analyses. Proteomic analysis of STARD10 binding partners was executed in INS1 (832/13) cell line. X-ray crystallography followed by molecular docking and lipid overlay assay were performed on purified STARD10 protein. Results: βStarD10KO islets had a sharply altered dense core granule appearance, with a dramatic increase in the number of ″rod-like″ dense cores. Correspondingly, basal secretion of proinsulin was increased. Amongst the differentially expressed genes in βStarD10KO islets, expression of the phosphoinositide binding proteins Pirt and Synaptotagmin 1 were decreased while lipidomic analysis demonstrated changes in phosphatidyl inositol levels. The inositol lipid kinase PIP4K2C was also identified as a STARD10 binding partner. STARD10 bound to inositides phosphorylated at the 3′ position and solution of the crystal structure of STARD10 to 2.3 Å resolution revealed a binding pocket capable of accommodating polyphosphoinositides. Conclusion: Our data indicate that STARD10 binds to, and may transport, phosphatidylinositides, influencing membrane lipid composition, insulin granule biosynthesis and insulin processing.
%G en %J bioRxiv %A Carrat, Gaelle R. %A Haythorne, Elizabeth %A Tomas, Alejandra %A Haataja, Leena %A Mueller, Andreas %A Arvan, Peter %A Piunti, Alexandra %A Cheng, Kaiying %A Huang, Mutian %A Pullen, Timothy %A Georgiadou, Eleni %A Stylianides, Theodoros %A Amirruddin, Nur Shabrina %A Salem, Victoria %A Distaso, Walter %A Cakebread, Andrew %A Heesom, Kate J. %A Lewis, Philip A. %A Hodson, David %A Briant, Linford J. %A Fung, Annie C. H. %A Sessions, Richard B. %A Alpy, Fabien %A Kong, Alice P. S. %A Benke, Peter I. %A Torta, Federico %A Teo, Adrian Kee Keong %A Leclerc, Isabelle %A Solimena, Michele %A Wigley, Dale B. %A Rutter, Guy A. %D 2020-03-26 %K WP4