Heat shock induces two distinct S6 protein kinase activities in quiescent mammalian fibroblasts. Academic Article uri icon

Overview

abstract

  • The regulation of S6 kinase activity was used to monitor perturbations of intracellular signaling activity during heat shock of quiescent murine and human fibroblasts. Previous reports on exponentially growing insect and plant cells had indicated that 40S ribosomal protein S6 is dephosphorylated during heat shock; thus inhibition of S6 kinase activity by heat shock was anticipated in NIH 3T3 fibroblasts and human cells (HeLa, diploid embryonic fibroblasts MRC-5, and skin-derived fibroblasts). Unexpectedly, two distinct S6 protein kinases were activated in quiescent fibroblasts after heat exposure. One of the enzymes was partially purified by sequential column chromatography and was determined to be equivalent to the enzyme activated by serum and other growth factors, referred to here as pp70-S6 protein kinase. The other protein S6 kinase, pp90rsk, was identified by a specific immunoprecipitation assay. Monitoring both enzymatic activities during heat shock revealed a temporal pattern of activation that was reversed when compared to non-stressed, mitogen-stimulated cells. Finally, heat shock stimulated protein S6 phosphorylation in cultured, quiescent mammalian cells. These data demonstrate that specific protein kinases can be activated during heat shock, and that some early mitogenic signals may also participate in the response of cells to physiologic stress.

publication date

  • August 1, 1991

Research

keywords

  • Hot Temperature
  • Interphase
  • Protein Kinases

Identity

Scopus Document Identifier

  • 0025850837

Digital Object Identifier (DOI)

  • 10.1002/jcp.1041480210

PubMed ID

  • 1880153

Additional Document Info

volume

  • 148

issue

  • 2