Granule docking and cargo release in pancreatic beta-cells.
Biphasic insulin secretion is required for proper insulin action and is observed not only in vivo, but also in isolated pancreatic islets and even single beta-cells. Late events in the granule life cycle are thought to underlie this temporal pattern. In the last few years, we have therefore combined live cell imaging and electrophysiology to study insulin secretion at the level of individual granules, as they approach the plasma membrane, undergo exocytosis and finally release their insulin cargo. In the present paper, we review evidence for two emerging concepts that affect insulin secretion at the level of individual granules: (i) the existence of specialized sites where granules dock in preparation for exocytosis; and (ii) post-exocytotic regulation of cargo release by the fusion pore.
Barg
Sebastian
S
Department of Cell Biology, Division of Medicine, Sir Alexander Fleming Building, Imperial College, London SW7 2AZ, UK. s.barg@imperial.ac.uk
Lindqvist
Anders
A
Obermüller
Stefanie
S
D000818:Animals; D003594:Cytoplasmic Granules / Q000378:metabolism*; D005089:Exocytosis; D006801:Humans; D007328:Insulin / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D007700:Kinetics
D007328:Insulin