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[MAP-kinase cascade analysis in transformed cell with different abilities to make G1/S block under serum starvation]

I A Savel'eva1, T V Bykova, N D Aksenov

  • 1Institute of Cytology, RAS, St. Petersburg. savir@freemail.ru

Tsitologiia
|October 3, 2003
PubMed

Insights

Oncogene transformation increases total kinase content but alters ERK1,2 phosphorylation differently. Some cells show a biphasic ERK1,2 phosphorylation response to serum deprivation, unlike stress kinases JNK and p38.

Area of Science:

  • Cellular signaling pathways
  • Oncogene-induced transformation
  • Signal transduction in cancer research

Background:

  • Serum deprivation is a common method to study cellular stress responses.
  • Mitogen-activated protein kinases (MAPK) like ERK1,2, JNK, and p38 are crucial in cell signaling.
  • Oncogene transformation can dysregulate cellular signaling pathways.

Purpose of the Study:

  • To investigate the regulation of ERK1,2, JNK1,2, and p38 kinases upon serum deprivation in oncogene-transformed rat embryo fibroblasts.
  • To determine how oncogene transformation affects kinase content and phosphorylation patterns.
  • To elucidate the specific role of ERK1,2 phosphorylation dynamics in cellular responses to serum withdrawal.

Main Methods:

  • Utilized oncogene-transformed rat embryo fibroblasts (E1A + E1B-19 kDa and E1A + c-Ha-ras).
  • Employed serum deprivation as a cellular stressor.
  • Analyzed kinase content and phosphorylation levels using immunoblotting techniques.

Main Results:

  • Oncogene transformation increased total kinase content irrespective of the oncogene.
  • ERK1,2 (Extracellular signal-regulated kinases 1 and 2) phosphorylation depended on the specific oncogene.
  • A biphasic phosphorylation pattern for ERK1,2 was observed in control and E1A + E1B-19 kDa cells during serum starvation, with initial dephosphorylation followed by recovery.
  • ERK1,2 phosphorylation remained unchanged in E1A + c-Ha-ras cells after serum withdrawal.
  • JNK (c-Jun N-terminal kinase) and p38 stress kinases showed no significant changes in phosphorylation across all cell types.

Conclusions:

  • Oncogene transformation impacts MAPK signaling, particularly ERK1,2 phosphorylation, in a context-dependent manner.
  • The biphasic ERK1,2 phosphorylation response in certain cell types suggests complex regulatory mechanisms during G1/S arrest.
  • JNK and p38 stress kinase pathways appear less sensitive to serum deprivation in these transformed cells.

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