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

Transforming growth factor (TGF)-beta1 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-beta treatment when compared with the wild-type myeloid cell line. To investigate the increased growth sensitivity of the v-Src-transformed myeloid cell line, 32D-src, to TGF-beta, we examined expression of the TGF-beta type II receptor (TGF-beta RII) gene in myeloid cell lines. Northem blot analysis showed that expression of approximately 8- and 6-kb species of TGF-beta RII transcripts was markedly increased in the 32D-src cell line. The expression of the TGF-beta 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-beta RII promoter activity through an AP1/ATF2-like sequence (-219 to -172), ETS binding sites (+1 to +36), and the inverted CCAAT box (-81 to -77). Novel DNA-protein complexes with ETS binding sites are significantly increased in v-src-transformed cell lines compared with the control cell line. These results suggest that v-Src induces activity of the TGF-beta RII promoter through multiple elements by inducing expression of nuclear proteins interacting with these elements.