Rab27a, actin and beta-cell endocytosis [Review]

The output and time-course of insulin release from pancreatic beta-cells are elegantly controlled. The secretory process comprises pre-exocytotic stages, exocytosis and post-exocytotic stages. The small GTPase Rab27a is known to regulate pre-exocytotic stages that determine the size of the readily-r...

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Bibliographic Details
Published in:ENDOCRINE JOURNAL 2011, Vol.58(1), pp.1-6
Main Authors: Kimura, Toshihide, Niki, Ichiro
Format: Article
Language:English
Subjects:
Actins - metabolism
Animals
Coronin
Endocytosis
Exocytosis
Exocytosis - drug effects
GTPase
Guanosine Diphosphate - metabolism
Guanosine Triphosphate - metabolism
Humans
Insulin - metabolism
Insulin Secretion
Insulin-Secreting Cells - metabolism
Insulin-Secreting Cells - physiology
Microfilament Proteins
rab GTP-Binding Proteins - physiology
rab27 GTP-Binding Proteins
Rab27a
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Summary:The output and time-course of insulin release from pancreatic beta-cells are elegantly controlled. The secretory process comprises pre-exocytotic stages, exocytosis and post-exocytotic stages. The small GTPase Rab27a is known to regulate pre-exocytotic stages that determine the size of the readily-releasable pool of insulin granules. GTP-Rab27a and its specific effectors are responsible for this process like other GTPases. Recently, we searched for Rab27a-interacting proteins and identified coronin 3. Unexpectedly, coronin 3 only bound GDP-Rab27a and this interaction regulated post-exocytotic stages via reorganization of the actin cytoskeleton. Since glucose converts Rab27a from the GTP- to GDP-bound form, we suggested that Rab27a plays a crucial role in stimulus-endocytosis coupling in pancreatic beta-cells, and that this is the key molecule for membrane recycling of insulin granules. In this review, we provide an overview of the roles of Rab27a and its GTP- and GDP-dependent effectors in the insulin secretory pathway of pancreatic beta-cells.
ISSN:0918-8959
1348-4540
DOI:10.1507/endocrj.K10E-391