Nuclear localization and regulation of erk- and rsk-encoded protein kinases. Academic Article uri icon

Overview

abstract

  • We demonstrate that members of the erk-encoded family of mitogen-activated protein (MAP) kinases (pp44/42mapk/erk) and members of the rsk-encoded protein kinases (RSKs or pp90rsk) are present in the cytoplasm and nucleus of HeLa cells. Addition of growth factors to serum-deprived cells results in increased tyrosine and threonine phosphorylation and in the activation of cytosolic and nuclear MAP kinases. Activated MAP kinases then phosphorylate (serine/threonine) and activate RSKs. Concurrently, a fraction of the activated MAP kinases and RSKs enter the nucleus. In addition, a distinct growth-regulated RSK-kinase activity (an enzyme[s] that phosphorylates recombinant RSK in vitro and that may be another member of the erk-encoded family of MAP kinases) was found associated with a postnuclear membrane fraction. Regulation of nuclear MAP kinase and RSK activities by growth factors and phorbol ester is coordinate with immediate-early gene expression. Indeed, in vitro, MAP kinase and/or RSK phosphorylates histone H3 and the recombinant c-Fos and c-Jun polypeptides, transcription factors phosphorylated in a variety of cells in response to growth stimuli. These in vitro studies raise the possibility that the MAP kinase/RSK signal transduction pathway represents a protein-Tyr/Ser/Thr phosphorylation cascade with the spatial distribution and temporal regulation that can account for the rapid transmission of growth-regulating information from the membrane, through the cytoplasm, and to the nucleus.

publication date

  • March 1, 1992

Research

keywords

  • Gene Expression Regulation, Enzymologic
  • Protein Kinases
  • Protein-Tyrosine Kinases
  • Proteins
  • Ribosomal Protein S6 Kinases, 90-kDa

Identity

PubMed Central ID

  • PMC369523

Scopus Document Identifier

  • 0026608787

PubMed ID

  • 1545823

Additional Document Info

volume

  • 12

issue

  • 3