Prenylcysteine analogs mimicking the C-terminus of GTP-binding proteins stimulate exocytosis from permeabilized HIT-T15 cells: comparison with the effect of Rab3AL peptide

Romano Regazzi, Takuya Sasaki, Kazuo Takahashi, Jean Christophe Jonas, Craig Volker, Jeffry B. Stock, Yoshimi Takai, Claes B. Wollheim

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Most guanine nucleotide binding proteins (G-proteins) possess an S-prenylated C-terminal cysteine whose carboxyl group can be reversibly methylated. The prenylcysteine analog N-acetyl-S-geranylgeranyl-cysteine (AGGC) (50 μM), a competitive inhibitor of prenylcysteine methyl transferases, introduced into streptolysin-O permeabilized HIT-T15 cells doubled the rate of basal (0.1 μM Ca2+) and of stimulated (10 μM Ca2+ or 100 μM GTPγS) insulin secretion in a reversible and ATP-dependent manner. N-acetyl-S-farnesyl-cysteine (AFC) was less potent while N-acetyl-S-geranyl-cysteine was inactive. Prenylcysteine action on exocytosis did not involve inhibition of G-protein methylation, since (1) the methyl ester derivative of AFC, an inefficient inhibitor of methyltransferases in HIT-T15 cell fractions, was as potent as AGGC in stimulating exocytosis; (2) S-adenosyl-homocysteine, a general inhibitor of methylation reactions, did not alter basal or GTPγS-triggered secretion while inhibiting Ca2+-induced insulin release. The binding of G-proteins to Rab/GDP-dissociation inhibitor, Rab3A/GTPase activating protein or rabphilin-3A was not affected by the prenylcysteine analogs. AGGC or AFC had the same effect on insulin release as a synthetic peptide mimicking the amino acid residues 52-67 of the G-protein Rab3A (Rab3AL). Moreover, the action on secretion of the combination of Rab3AL and prenylcysteines was not additive. We propose that the prenylcysteines and the Rab3AL peptide influence exocytosis by affecting the association of Rab3A with different proteins of the exocytotic machinery of insulin-secreting cells.

Original languageEnglish (US)
Pages (from-to)269-278
Number of pages10
JournalBBA - Molecular Cell Research
Volume1268
Issue number3
DOIs
StatePublished - Sep 21 1995

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

Keywords

  • Guanine nucleotide binding protein
  • HIT-T15 cell
  • Prenylcysteine
  • Rab exocyotic effector protein

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