Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Polyamines Are Essential for Cell Transformation by pp60v-src: Delineation of Molecular Events Relevant for the Transformed Phenotype

Erkki Hölttä, Merja Auvinen and Leif C. Andersson
The Journal of Cell Biology
Vol. 122, No. 4 (Aug., 1993), pp. 903-914
Stable URL: http://www.jstor.org/stable/1615878
Page Count: 12
  • More info
  • Cite this Item
Polyamines Are Essential for Cell Transformation by pp60v-src: Delineation of Molecular Events Relevant for the Transformed Phenotype
Preview not available

Abstract

Ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis, becomes upregulated during cell proliferation and transformation. Here we show that intact ODC activity is needed for the acquisition of a transformed phenotype in rat 2R cells infected with a temperature-sensitive mutant of Rous sarcoma virus. Addition of the ODC inhibitor α-difluoromethyl ornithine (DFMO) to the cells (in polyamine-free medium) before shift to permissive temperature prevented the depolymerization of filamentous actin and morphological transformation. Polyamine supplementation restored the transforming potential of pp60v-src. DFMO did not interfere with the expression of pp60v-src or its in vitro tyrosine kinase activity. The tyrosine phosphorylation of most cellular proteins, including ras GAP, did not either display clear temperature- or DFMO-sensitive changes. A marked increase was, however, observed in the tyrosine phosphorylation of phosphatidylinositol 3-kinase and proteins of 33 and 36 kD upon the temperature shift, and these hyperphosphorylations were partially inhibited by DFMO. A DFMO-sensitive increase was also found in the total phosphorylation of calpactins I and II. The well-documented association of GAP with the phosphotyrosine-containing proteins p190 and p62 did not correlate with transformation, but a novel 42-kD tyrosine phosphorylated protein was complexed with GAP in a polyamine- and transformation- dependent manner. Further, tyrosine phosphorylated proteins of 130, 80/85, and 36 kD were found to coimmunoprecipitate with pp60v-src in a transformation-related manner. Altogether, this model offers a tool for sorting out the protein phosphorylations and associations critical for the transformed phenotype triggered by pp60v-src, and implicates a pivotal role for polyamines in cell transformation.

Page Thumbnails

  • Thumbnail: Page 
903
    903
  • Thumbnail: Page 
904
    904
  • Thumbnail: Page 
905
    905
  • Thumbnail: Page 
906
    906
  • Thumbnail: Page 
907
    907
  • Thumbnail: Page 
908
    908
  • Thumbnail: Page 
909
    909
  • Thumbnail: Page 
910
    910
  • Thumbnail: Page 
911
    911
  • Thumbnail: Page 
912
    912
  • Thumbnail: Page 
913
    913
  • Thumbnail: Page 
914
    914