Actin assembly controlled by GDP-Rab27a is essential for endocytosis of the insulin secretory membrane.
We have recently reported that GDP-bound Rab27a regulates endocytosis of the insulin secretory membrane via its binding to coronin 3, an actin-binding protein. The aim of this study was to examine the participation of actin assembly in the Rab27a-dependent regulation of endocytosis using a pancreatic beta cell line, MIN6. Coronin 3 promoted F-actin bundling only in the presence of GDP-Rab27a. This effect was independent of coronin-3-binding to the actin-related proteins 2 and 3 (Arp2/3). Uptake of anti-phogrin-lumen antibody into MIN6 was inhibited by anti-coronin-3-C antibody which recognizes the actin-binding site. This inhibition was also observed with coronin-3-R28D, which lacks in actin binding. These results suggest that coronin 3 is a genuine GDP-Rab27a effector, and that controls endocytosis of the secretory membrane via modulating actin assembly in pancreatic beta-cells.
Department of Pharmacology, Oita University Faculty of Medicine at Oita, Japan.
Toshihide
T
Kimura
Shigeki
S
Taniguchi
Ichiro
I
Niki
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism*; D002522:Chlorocebus aethiops; D004705:Endocytosis; D006153:Guanosine Diphosphate / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000075745:rab27 GTP-Binding Proteins
D000199:Actins; D007328:Insulin; D008840:Microfilament Proteins; D000075745:rab27 GTP-Binding Proteins; C072061:coronin proteins; D006153:Guanosine Diphosphate; C512962:Rab27a protein, mouse; D020691:rab GTP-Binding Proteins