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Mastoparan stimulates GABA release from MIN6 cells: relationship between SNARE proteins and mastoparan action

M Ohara-Imaizumi1, Y Nakamichi, S Ozawa

  • 1Department of Biochemistry, Kyorin University School of Medicine, Mitaka, Tokyo, 181-8611, Japan.

Biochemical and Biophysical Research Communications
|December 14, 2001
PubMed

Insights

Mastoparan triggers both GABA and insulin release from beta cells. However, SNARE proteins differentially regulate these exocytosis pathways, impacting insulin release more than GABA release.

Area of Science:

  • Endocrinology
  • Cell Biology
  • Neuroscience

Background:

  • Beta cells are crucial for regulating blood glucose through insulin secretion.
  • GABAergic signaling in pancreatic beta cells plays a role in regulating insulin release.
  • Mastoparan, a peptide toxin, is known to affect cellular processes, including exocytosis.

Purpose of the Study:

  • To investigate the mechanism by which mastoparan stimulates GABA and insulin release from MIN6 beta cells.
  • To elucidate the role of SNARE proteins in mastoparan-induced exocytosis of GABA and insulin.

Main Methods:

  • Utilized MIN6 beta cell line for experiments.
  • Employed tetanus toxin C1 light chain expression to assess GABA release pathways.
  • Used adenovirus-mediated gene transfer to overexpress specific SNARE proteins (syntaxin 1A, SNAP-25) and a dominant-negative alpha-SNAP mutant.
  • Measured GABA and insulin release in response to mastoparan stimulation under various experimental conditions.

Main Results:

  • Mastoparan stimulated both GABA and insulin release from MIN6 beta cells.
  • Tetanus toxin C1 light chain expression reduced mastoparan-induced GABA release.
  • Overexpression of syntaxin 1A and SNAP-25 inhibited mastoparan-induced insulin release but not GABA release.
  • Overexpression of a dominant-negative alpha-SNAP mutant did not affect mastoparan-induced GABA or insulin release, despite inhibiting glucose-stimulated insulin release.

Conclusions:

  • Mastoparan stimulates GABA exocytosis through a vesicular transport mechanism.
  • SNARE proteins play distinct roles in the exocytosis of insulin and GABA induced by mastoparan.
  • The findings highlight differential regulation of exocytosis pathways for insulin and GABA in beta cells.

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