Figure 7.

Reducing Noggin levels enhances satellite cell proliferation but inhibits differentiation. To further understand the role of Noggin in myogenic progression, we used siRNA-mediated knockdown of Noggin protein. (a) Efficient Noggin knockdown in plated satellite cell-derived myoblasts was confirmed by immunostaining for Noggin 3 days after siRNA (Noggin si) transfection. (b, quantified in c–e) The effects of Noggin knockdown were analysed by co-immunostaining for MyHC and Ki67, which revealed an increase in myoblast proliferation, but a reduction in differentiation and fusion into large myotubes. (f) Western blotting also showed that Noggin siRNA reduced myogenin levels in plated satellite cells. (g, quantified in h) The effect of Dorsomorphin (1 μM) treatment to inhibit BMP signalling on Noggin siRNA-transfected cells was analysed by immunostaining for MyHC. Dorsomorphin reversed the fusion defect induced by Noggin knockdown. Mean±S.D. from at least three independent experiments is shown. Asterisk indicates that data are significantly different from control (P<0.05) using paired one-tail t-test. Scale bar equals 30 μm