Mitogenic effects of pertussis toxin-sensitive G-protein α subunits: The mitogenic action of αi2 in NIH 3T3 cells is mimicked by αi1, but not αi3

Sylvie Hermouet, Philippe de Mazancourt, Allen M. Spiegel

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16 Scopus citations


In fibroblasts and other cell types, pertussis toxin (PTX) inhibits DNA synthesis in response to serum and certain growth factors. GTPase deficient forms of the PTX-sensitive G-protein αi2 subunit have been shown to induce partial transformation in fibroblasts. In order to determine whether other PTX-sensitive G-protein scan stimulate mitogenic pathways, we stably expressed constitutively activated G-protein αi1 and αi3 subunits in NIH 3T3 cells. Expression of activated αi1, αi2 or αi3 results in inhibition of forskolin-stimulated cAMP accumulation in intact cells. Constitutively activated αi1, but not αi3, induces a loss of contact inhibition, a loss of anchorage-dependence, a reduced serum requirement and a decreased doubling time in NIH 3T3 cells. We conclude that αi1 and αi2 are both capable of transducing mitogenic signals, but that αi3 is not involved in the regulation of fibroblast growth. Furthermore, adenylyl cyclase inhibition is clearly not sufficient to explain the effect of αi2 on fibroblast growth.

Original languageEnglish (US)
Pages (from-to)215-225
Number of pages11
JournalCellular Signalling
Issue number2
StatePublished - Mar 1993
Externally publishedYes


  • Fibroblasts
  • PTX-sensitive G-proteins
  • proliferation

ASJC Scopus subject areas

  • Cell Biology


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