Density Dependent Elevation of phosphatidylinositol-3 Kinase Level in Rat 3Y1 Cells

Biochim Biophys Acta. 1998 Jan 2;1401(1):113-20. doi: 10.1016/s0167-4889(97)00108-0.


We have explored the levels of phosphatidylinositol-3 kinase protein during culture of rat 3Y1 cells. Confluent cell cultures exhibited a higher level of phosphatidylinositol-3 kinase compared with that of growing cells. After replating of the cells on fresh dishes, the level of phosphatidylinositol-3 kinase returned to that of growing cells within 24h. This density-dependent regulation of the phosphatidylinositol-3 kinase level was not lined to cell growth, because growth arrest by serum starvation did not cause elevation of the phosphatidylinositol-3 kinase level. Northern blotting analysis revealed that this regulation was based on the transcriptional level. After cell growth was arrested by contact inhibition, elevation of the level of phosphatidylinositol-3,4,5-trisphosphate was detected suggesting that phosphatidylinositol-3 kinase was activated in these cells. These effects were not seen in src-transformed 3Y1 cells, suggesting that this regulation was lost in transformed cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Count
  • Cell Division
  • Cell Line
  • Cell Line, Transformed
  • Contact Inhibition / physiology*
  • Fibroblasts / cytology
  • Fibroblasts / enzymology*
  • Genes, src
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphatidylinositol Phosphates / analysis
  • RNA, Messenger / analysis
  • Rats
  • Transcription, Genetic / physiology


  • Phosphatidylinositol Phosphates
  • RNA, Messenger
  • phosphatidylinositol 3,4,5-triphosphate
  • Phosphatidylinositol 3-Kinases