Mechanism of induction of transforming growth factor-beta type II receptor gene expression by v-Src in murine myeloid cells.

Transforming growth factor (TGF)-b1 plays an important role during hematopoiesis. Previously, we had shown that the growth of a v-Src-transformed myeloid cell line was markedly more inhibited by TGF-b treatment when compared with the wild-type myeloid cell line. To investigate the increased growth sensitivity of the v-Srctransformed myeloid cell line, 32D-src, to TGF-b ,w e examined expression of the TGF-b type II receptor (TGFb RII) gene in myeloid cell lines. Northern blot analysis showed that expression of ;8- and 6-kb species of TGFb RII transcripts was markedly increased in the 32D-src cell line. The expression of the TGF-b RII promoter linked to a reporter gene was increased 23-fold by v-Src. DNA transfection and electrophoretic mobility shift assay revealed that v-Src induces TGF-b RII promoter activity through an AP1/ATF2-like sequence (2219 to 2172), ETS binding sites (1 1t o136), and the inverted CCAAT box (281 to 277). Novel DNA-protein complexes with ETS binding sites are significantly increased in v-srctransformed cell lines compared with the control cell line. These results suggest that v-Src induces activity of the TGF-b RII promoter through multiple elements by inducing expression of nuclear proteins interacting with these elements.