PDGF- and insulin-dependent pp70S6k activation mediated by phosphatidylinositol-3-OH kinase. Academic Article uri icon

Overview

abstract

  • Platelet-derived growth factor receptor (PDGF-R) phosphorylation at tyrosines 740/751 and insulin receptor phosphorylation of insulin receptor substrate-1 effects the recruitment and activation of phosphatidylinositol-3-OH kinase (PI(3)K). Changes in PI(3)K activity correlate with cell growth but its downstream signal transducers are unknown. Activation of the 70/85K S6 kinases (pp70S6k) by serine phosphorylation results in 40S ribosomal protein S6 phosphorylation and is important for G1 cell-cycle transition in a variety of cells. Although receptor tyrosine kinases activate the microtubule-associated protein kinase cascade through SH2-/SH3-adaptor proteins, Sos and c-Ras, it is unclear how tyrosine kinases are coupled to the pp70S6k phosphorylation cascade. Here we report that PI(3)K mediates PDGF or insulin receptor signalling to pp70S6k. PI(3)K-mediated activation of pp70S6k is independent of conventional protein kinase C isoforms. Additionally, rapamycin blocks pp70S6k activation by all mitogens, without inhibiting PI(3)K, and acts downstream in this signalling system.

publication date

  • July 7, 1994

Research

keywords

  • Phosphotransferases (Alcohol Group Acceptor)
  • Platelet-Derived Growth Factor
  • Protein Serine-Threonine Kinases
  • Protein-Serine-Threonine Kinases

Identity

Scopus Document Identifier

  • 0028178928

PubMed ID

  • 8015612

Additional Document Info

volume

  • 370

issue

  • 6484