Transcriptional regulation of the Bmp2 gene - Retinoic acid induction in F9 embryonal carcinoma cells and Saccharomyces cerevisiae

Bmp2, a highly conserved member of the transforming growth factor-beta gene family, is crucial for normal development. Retinoic acid, combined with cA MP analogs, sharply induces the Bmp2 mRNA during the differentiation of F9 embryonal carcinoma cells into parietal endoderm, Retinoic acid (RA) also i nduces the Bmp2 gene in chick limb buds. Since normal Bmp2 expression may r equire an endogenous retinoid signal and aberrant Bmp2 expression may cause some aspects of RA-induced teratogenesis, we studied the mechanism underly ing the induction of Bmp2. Measurements of the Bmp2 mRNA half-life and nucl ear run-on assays indicated that RA stimulated the transcription rate of th e Bmp2 gene. The results of ribonuclease protection and primer extension as says indicated that Bmp2 transcription started 2,127 nucleotides upstream o f the translation start site in F9 cells. To identify genetic elements cont rolling this transcription rate increase, upstream and downstream genomic s equences flanking the Bmp2 gene were screened using chloramphenicol acetylt ransferase reporter genes in F9 cells and beta-galactosidase reporter genes in Saccharomyces cerevisiae that were cotransformed with retinoic acid rec eptor and retinoid X receptor expression plasmids, RA-dependent transcripti onal activation was detected between base pairs -2,373 and -2,316 relative to the translation start site. We also identified a required Sp1 binding si te between -2,308 and -2,298, The data indicate that Bmp2 is directly regul ated by retinoic acid-bound receptors and Sp1.