Smad3 in the mammary epithelium has a nonredundant role in the induction of apoptosis, but not in the regulation of proliferation or differentiation by transforming growth factor-beta

Yu-an Yang, Binwu Tang, Gertraud Robinson, Lothar Hennighausen, Steven G Brodie, Chu-Xia Deng, Lalage M Wakefield
2002 Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research  
Transforming growth factor-beta (TGF-beta) regulates proliferation, morphogenesis, and functional differentiation in the mammary gland and plays complex roles in mammary tumorigenesis. Here we show that the signaling mediators Smad1-Smad5 are expressed at all stages of mammary gland development. To begin to investigate which Smads mediate which TGF-beta responses, we have analyzed mammary gland development in Smad3 null mice. Smad3 null virgin females showed delayed mammary gland development.
more » ... wever, this phenotype was secondary to ovarian insufficiency because Smad3 null mammary epithelium developed normally in hormonally supplemented Smad3 null mice or when transplanted into wild-type hosts. Absence of Smad3 had no effect on the ability of TGF-beta to inhibit the growth of mammary epithelial cells in culture, and no compensatory changes in expression or activation of Smad2 were seen in the Smad3 null epithelium. A small but significant decrease in apoptotic cells was seen in involuting glands from Smad3 null transplants. The results suggest that epithelial Smad3 is dispensable for TGF-beta effects on proliferation and differentiation in the mammary gland, but that it contributes in a nonredundant manner to the induction of apoptosis.
pmid:11959813 fatcat:grafdwlzgvgxdhute2guk4ib5m