Calcium as a second messenger of the action of transforming growth factor-beta on insulin secretion

Mol Cell Endocrinol. 1996 Mar 1;117(1):1-6. doi: 10.1016/0303-7207(95)03726-8.

Abstract

In MIN6 insulinoma cells, transforming growth factor-beta (TGF-beta) induced the oscillatory elevation of the cytoplasmic free calcium concentration, [Ca2+]c, in the presence of 5.5 mM glucose. The increase in [Ca2+]c induced by TGF-beta was totally dependent on calcium entry and attenuated by nifedipine or nickel chloride. In contrast, carbachol elevated [Ca2+]c in the presence of nickel chloride. When the plasma membrane was hyperpolarized by diazoxide, TGF-beta did not raise [Ca2+]c, whereas both carbachol and depolarizing concentration of potassium elevated [Ca2+]c under the same conditions. TGF-beta did not affect either the cellular cyclic AMP or inositol trisphosphate levels. In the presence of 5.5 mM glucose, TGF-beta induced a 3-fold increase in insulin secretion and the effect of TGF-beta was blocked by either nifedipine or nickel chloride. TGF-beta did not stimulate insulin secretion in the presence of 100 microM diazoxide, whereas both carbachol and 40 mM potassium chloride significantly increased insulin secretion. These results suggest that TGF-beta induces the oscillatory elevation of [Ca2+]c in MIN6 cells by stimulating calcium entry via voltage-dependent calcium channels. Calcium is an intracellular messenger of the action of TGF-beta on insulin secretion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium / metabolism*
  • Cyclic AMP / metabolism
  • Humans
  • Inositol Phosphates / metabolism
  • Insulin / metabolism*
  • Insulin Secretion
  • Nickel / pharmacology
  • Nifedipine / pharmacology
  • Recombinant Proteins / pharmacology
  • Transforming Growth Factor beta / pharmacology*
  • Tumor Cells, Cultured

Substances

  • Inositol Phosphates
  • Insulin
  • Recombinant Proteins
  • Transforming Growth Factor beta
  • nickel chloride
  • Nickel
  • Cyclic AMP
  • Nifedipine
  • Calcium