Regulated Exocytosis and Kiss-and-Run of Synaptic-Like Microvesicles in INS-1 and Primary Rat {beta}-Cells.

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Abstract

We have applied cell-attached capacitance measurements to investigate whether synaptic-like microvesicles (SLMVs) undergo regulated exocytosis in insulinoma and primary pancreatic beta-cells. SLMV and large dense-core vesicle (LDCV) exocytosis was increased 1.6- and 2.4-fold upon stimulation with 10 mmol/l glucose in INS-1 cells. Exocytosis of both types of vesicles was coupled to Ca(2+) entry through l-type channels. Thirty percent of SLMV exocytosis in INS-1 and rat beta-cells was associated with transient capacitance increases consistent with kiss-and-run. Elevation of intracellular cAMP (5 micromol/l forskolin) increased SLMV exocytosis 1.6-fold and lengthened the duration of kiss-and-run events in rat beta-cells. Experiments using isolated inside-out patches of INS-1 cells revealed that the readily releasable pool (RRP) of SLMVs preferentially undergoes kiss-and-run exocytosis (67%), is proportionally larger than the LDCV RRP, and is depleted more quickly upon Ca(2+) stimulation. We conclude that SLMVs undergo glucose-regulated exocytosis and are capable of high turnover. Following kiss-and-run exocytosis, the SLMV RRP may be reloaded with gamma-aminobutyric acid and undergo several cycles of exo- and endocytosis. Our observations support a role for beta-cell SLMVs in a synaptic-like function of rapid intra-islet signaling.

Details

Authors
  • Patrick MacDonald
  • Stefanie Obermüller
  • Jenny Vikman
  • Juris Galvanovskis
  • Patrik Rorsman
  • Lena Eliasson
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Endocrinology and Diabetes
Original languageEnglish
Pages (from-to)736-743
JournalDiabetes
Volume54
Issue number3
Publication statusPublished - 2005
Publication categoryResearch
Peer-reviewedYes