An activated mutant of the alpha subunit of G(o) increases neurite outgrowth via protein kinase C

Brain Res Dev Brain Res. 1995 Jun 27;87(1):77-86. doi: 10.1016/0165-3806(95)00061-h.

Abstract

The GTP-binding protein, G(o), is present at very high concentration in the neuronal growth cone membrane. The expression of activated mutants of the a subunit of G(o) increases neurite outgrowth. To determine the intracellular mechanism for this outgrowth, we have examined activated alpha o-dependent outgrowth in the presence of agents which modulate different signal transduction cascades. Activation of protein kinase C with phorbol esters or with diacylglycerol prevents the alpha o-dependent increase in neurite extension. Inhibition of protein kinase C with staurosporine, with H7, or with long-term, high dose phorbol ester treatment resulted in greater neurite elongation, and no further increase after activated alpha o transfection. The protein phosphatase inhibitor, okadaic acid, also blocked the effect of activated alpha o. In contrast, tyrosine kinase inhibitors and agents which alter cAMP levels did not alter activated alpha o-dependent neurite extension. We tested a number of compounds which alter intracellular calcium levels. TMB-8 and thapsigargin prevented an increase in outgrowth by activated alpha o, but diltiazem, Bay K8644 and dantrolene had no effect on activated alpha o-dependent outgrowth. These studies suggest that activated alpha o increases neurite outgrowth by inhibiting protein kinase C and by modulating intracellular calcium release.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alkaloids / pharmacology
  • Animals
  • Calcium / metabolism
  • Calcium Channel Blockers / pharmacology
  • Calcium-Transporting ATPases / antagonists & inhibitors
  • Dose-Response Relationship, Drug
  • Enzyme Inhibitors / pharmacology
  • Ethers, Cyclic / pharmacology
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / ultrastructure*
  • Gallic Acid / analogs & derivatives
  • Gallic Acid / pharmacology
  • Mutation / physiology
  • Neurites / physiology*
  • Okadaic Acid
  • PC12 Cells / physiology*
  • PC12 Cells / ultrastructure
  • Protein Kinase C / agonists
  • Protein Kinase C / physiology*
  • Rats
  • Second Messenger Systems / physiology
  • Staurosporine
  • Terpenes / pharmacology
  • Thapsigargin
  • Transfection

Substances

  • Alkaloids
  • Calcium Channel Blockers
  • Enzyme Inhibitors
  • Ethers, Cyclic
  • Terpenes
  • Okadaic Acid
  • 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate
  • Gallic Acid
  • Thapsigargin
  • Protein Kinase C
  • GTP-Binding Proteins
  • Calcium-Transporting ATPases
  • Staurosporine
  • Calcium