Functional regulation of osteoblastic cells by the interaction of activin-A with follistatin.
- M Hashimoto,
- A Shoda,
- S Inoue,
- R Yamada,
- T Kondo,
- T Sakurai,
- N Ueno and
- M Muramatsu
Abstract
A high number of 125I-activin-A binding sites (an apparent Kd of 260 pM and 5,600 sites/cell) were observed on MC3T3-E1 cells, a well characterized osteoblastic cell line. Activin-A has a mitogenic effect on these cells, with the greatest influence being observed on cells in an undifferentiated state, as well as a suppressive effect on the alkaline phosphatase activity. Northern and ligand blotting analyses revealed that these osteoblastic cells produce follistatin, which was down-regulated by retinoic acid treatment. Because follistatin is an activin-A-binding protein, we suggest that activin-A modulates the function of osteoblastic cells by being regulated by follistatin during differentiation.
