[Gene structure and transformation mechanism of HTLV-I].

HTLV-I is the etiological agent of the adult T cell leukemia. HTLV-I genome contains the novel pX region in addition to the genes common to all retroviruses. Tax, encoded at the pX region, may play a central role in cellular transformation, however, little information is available on the mechanism. Tax transactivates transcription through three different pathways, namely, CRE, kB motif and CArG box mediated pathways. In ras cooperative focus formation in REF, transcriptional activation through the CArG box seems to play an important role, although transcription through the CRE pathway plays a central role in tax-mediated transformation of Rat-2 cells. These results suggest that the mechanism of transformation by tax varies with the cell type and/or the property of transformation.