Stimulation of insulin release from permeabilized HIT-T15 cells by a synthetic peptide corresponding to the effector domain of the small GTP-binding protein rab3.
A synthetic peptide (rab3AL) corresponding to the effector domain of rab3, a small GTP-binding protein, stimulated basal and potentiated Ca(2+)- as well as GTP gamma S-evoked insulin secretion about 2-fold from streptolysin-O permeabilized HIT cells. This effect was specific, since the analogous peptides of ras or rab1 did not affect the exocytotic event. The more than additive effect of rab3AL on Ca2+ or GTP gamma S stimulation indicates a distinct mode of action of the peptide. The partial loss of cytosolic proteins from permeabilized cells was accompanied by a faster run-down of the secretory response to Ca2+ than the one to GTP gamma S. The persistent effect of rab3AL under these conditions points to a membrane localization of its target. These results suggest that rab3 and its effector are involved in the regulation of insulin secretion.
Département de Médecine, Centre Médical Universitaire, Geneva, Switzerland.
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G
Li
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Regazzi
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Balch
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Wollheim
D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D005089:Exocytosis / Q000187:drug effects; D019204:GTP-Binding Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D009419:Nerve Tissue Proteins / Q000138:chemical synthesis / Q000494:pharmacology*; D010455:Peptides / Q000138:chemical synthesis / Q000494:pharmacology; D013301:Streptolysins; D020692:rab3 GTP-Binding Proteins
D007328:Insulin; D009419:Nerve Tissue Proteins; D010455:Peptides; D013301:Streptolysins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins; D002118:Calcium