Dynamin is functionally coupled to insulin granule exocytosis.
The insulin granule integral membrane protein marker phogrin-green fluorescent protein was co-localized with insulin in Min6B1 beta-cell secretory granules but did not undergo plasma membrane translocation following glucose stimulation. Surprisingly, although expression of a dominant-interfering dynamin mutant (Dyn/K44A) inhibited transferrin receptor endocytosis, it had no effect on phogringreen fluorescent protein localization in the basal or secretagogue-stimulated state. By contrast, co-expression of Dyn/K44A with human growth hormone as an insulin secretory marker resulted in a marked inhibition of human growth hormone release by glucose, KCl, and a combination of multiple secretagogues. Moreover, serial pulse depolarization stimulated an increase in cell surface capacitance that was also blocked in cells expressing Dyn/K44A. Similarly, small interference RNA-mediated knockdown of dynamin resulted in marked inhibition of glucose-stimulated insulin secretion. Together, these data suggest the presence of a selective kiss and run mechanism of insulin release. Moreover, these data indicate a coupling between endocytosis and exocytosis in the regulation of beta-cell insulin secretion.
Min
Le
L
Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794.
Leung
Yuk M
YM
Departments of Medicine and Physiology, University of Toronto, Toronto M5S 1A8, Canada; Department of Physiology, China Medical University, Taichung 404, Taiwan.
Tomas
Alejandra
A
Department of Genetic Medicine and Development, Centre Médical Universitaire, 1 rue Michel-Servet, 1211 Geneva, Switzerland.
Watson
Robert T
RT
Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794.
Gaisano
Herbert Y
HY
Departments of Medicine and Physiology, University of Toronto, Toronto M5S 1A8, Canada.
Halban
Philippe A
PA
Department of Genetic Medicine and Development, Centre Médical Universitaire, 1 rue Michel-Servet, 1211 Geneva, Switzerland.
Pessin
Jeffrey E
JE
Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794.
Hou
June Chunqiu
JC
Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794. Electronic address: Hou@pharm.stonybrook.edu.
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D034281:Dynamins / Q000235:genetics / Q000502:physiology*; D005089:Exocytosis; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D009154:Mutation; D011189:Potassium Chloride / Q000737:chemistry; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000378:metabolism
D007328:Insulin; D034741:RNA, Small Interfering; D049452:Green Fluorescent Proteins; D011189:Potassium Chloride; D034281:Dynamins