Organization and dynamics of the cortical complexes controlling insulin secretion in β-cells
Noordstra, Ivar; van den Berg, Cyntha M; Boot, Fransje W J; Katrukha, Eugene A; Yu, Ka Lou; Tas, Roderick P; Portegies, Sybren; Viergever, Bastiaan J; de Graaff, Esther; Hoogenraad, Casper C; de Koning, Eelco J P; Carlotti, Françoise; Kapitein, Lukas C; Akhmanova, Anna
(2022) Journal of Cell Science, volume 135, issue 3, pp. 1 - 18
(Article)
Abstract
Insulin secretion in pancreatic β-cells is regulated by cortical complexes that are enriched at the sites of adhesion to extracellular matrix facing the vasculature. Many components of these complexes, including bassoon, RIM, ELKS and liprins, are shared with neuronal synapses. Here, we show that insulin secretion sites also contain the
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non-neuronal proteins LL5β (also known as PHLDB2) and KANK1, which, in migrating cells, organize exocytotic machinery in the vicinity of integrin-based adhesions. Depletion of LL5β or focal adhesion disassembly triggered by myosin II inhibition perturbed the clustering of secretory complexes and attenuated the first wave of insulin release. Although previous analyses in vitro and in neurons have suggested that secretory machinery might assemble through liquid-liquid phase separation, analysis of endogenously labeled ELKS in pancreatic islets indicated that its dynamics is inconsistent with such a scenario. Instead, fluorescence recovery after photobleaching and single-molecule imaging showed that ELKS turnover is driven by binding and unbinding to low-mobility scaffolds. Both the scaffold movements and ELKS exchange were stimulated by glucose treatment. Our findings help to explain how integrin-based adhesions control spatial organization of glucose-stimulated insulin release.
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Keywords: Cell cortex, Focal adhesion, Insulin secretion, Knock-in mouse, Liquid-liquid phase separation, Single-molecule imaging, Cell Biology
ISSN: 0021-9533
Publisher: Company of Biologists Ltd
Note: Funding Information: The work is supported by the Netherlands Organization for Health Research (ZonMw) TOP grants 91207010 and 91216006, the Netherlands Organization for Scientific Research (Nederlandse Organisatie voor Wetenschappelijk Onderzoek) ALW-VICI grant 865.08.002, Human Frontier Science Program Research Grant RGP0001/2016 and European Foundation for the Study of Diabetes (EFSD) grant to A.A. I.N. was supported by the European Molecular Biology Organization (EMBO Funding Information: The work is supported by the Netherlands Organization for Health Research (ZonMw) TOP grants 91207010 and 91216006, the Netherlands Organization for Scientific Research (Nederlandse Organisatie voor Wetenschappelijk Onderzoek) ALW-VICI grant 865.08.002, Human Frontier Science Program Research Grant RGP0001/2016 and European Foundation for the Study of Diabetes (EFSD) grant to A.A. I.N. was supported by the European Molecular Biology Organization (EMBO ALTF 251-2018). Open Access funding provided by Utrecht University. Deposited in PMC for immediate release. Publisher Copyright: © 2022. Published by The Company of Biologists Ltd
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