Activation of phospholipase C by G-protein beta gamma subunits in DDT1MF-2 cells

Eur J Pharmacol. 1995 Feb 15;288(3):393-8. doi: 10.1016/0922-4106(95)90055-1.

Abstract

Adenosine A1 receptors directly stimulate inositol phospholipid hydrolysis and Ca2+ mobilization through a pertussis toxin sensitive mechanism in DDT1MF-2 cells. In the present study we have investigated whether G protein beta gamma subunits (G beta gamma) are capable of stimulating phospholipase C in DDT1MF-2 cell membrane preparations using lipid vesicles containing [3H]phosphatidylinositol 4,5-bisphosphate. DDT1MF-2 cell membrane and soluble fractions were found to contain phospholipase C activity which was stimulated by increases in free Ca2+ ion concentration. G beta gamma purified from bovine retinal transducin produced significant increases in phospholipase C activity in DDT1MF-2 cell membranes. G beta gamma-dependent activation of phospholipase C, while virtually absent in the presence of low Ca2+ ion concentrations, increased markedly with increasing free Ca2+ ion concentration. These data suggest that membrane bound phospholipase C in DDT1MF-2 cells is sensitive to Ca2+, and may be stimulated conditionally by G beta gamma subunits, i.e. G beta gamma subunits activate the enzyme only in the presence of Ca2+. G beta gamma subunits also stimulated soluble phospholipase C in DDT1MF-2 cells. These findings support the hypothesis that Gi beta gamma subunits are involved in adenosine A1 receptor stimulated phospholipase C/Ca2+ signaling in DDT1MF-2 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Calcium / pharmacology
  • Cell Line
  • Cricetinae
  • Dose-Response Relationship, Drug
  • Enzyme Activation
  • GTP-Binding Proteins / metabolism*
  • Male
  • Muscle, Smooth / drug effects
  • Muscle, Smooth / enzymology*
  • Type C Phospholipases / metabolism*

Substances

  • Type C Phospholipases
  • GTP-Binding Proteins
  • Calcium