Transcription factors STAT1 and STAT3 are localized in different compartments of rat embryo fibroblasts transformed by E1A and Ha-Ras oncogenes
Poselova, T.V.; Evdonin, A.L.; Medvedeva, N.D.; Pospelov, V.A.
Tsitologiia 40(12): 1074-1079
1998
ISSN/ISBN: 0041-3771 PMID: 10188224 Document Number: 486742
Intracellular distribution of STAT1 and STAT3 transcription factors in normal fibroblasts (REF) and in E1A + Ha-Ras transformed cells has been studied by means of indirect immunofluorescence. The obtained data evidence that in REF cells, in response to the growth factor addition, STAT1 and STAT3 proteins are redistributed from the cytoplasm to the nucleus. In transformants E1A + Ha-Ras, however, significantly different pictures can be seen: while STAT1 is found to be constitutively localized in the cell nuclei, STAT3 is predominantly revealed in the cytoplasm. The data obtained from fractionation of subcellular structures confirm in general the immunofluorescence results on the cytoplasmic localization of STAT3 protein in E1A + Ha-Ras transformants. Thus, transformation of REF cells with E1A + Ha-Ras oncogenes causes a constitutive activation of STAT1 and STAT3 transcription factors, the proteins, however, being distributed in different cell compartments.