Muscular atrophy of caveolin-3–deficient mice is rescued by myostatin inhibition
J. Clin. Invest. Yutaka Ohsawa, et al. 116:2924 doi:10.1172/JCI28520 [Go to this article.]

Figure 1
Caveolin-3 binds to the type I myostatin receptors and suppresses their activation. (A) Colocalization of caveolin-3 (CAV-3) and type I myostatin receptors (ALK4 and ALK5). COS-7 cells transfected with caveolin-3 and/or ALK4 or ALK5 were double labeled with an anti-rabbit caveolin-3 polyclonal Ab (CAV) and an anti-mouse HA mAb (ALK). The enlarged images of the boxed regions are shown below the original pictures. White arrowheads indicate colocalization of caveolin-3 with ALK4 or ALK5. Scale bars: 10 μm. (B) Interaction of caveolin-3 and ALK4 (upper panels) or ALK5 (lower panels). Cell lysates from COS-7 cells cotransfected with FLAG- or HA-tagged caveolin-3 (CAV-3) and either HA- or FLAG-tagged type I receptor were immunoprecipitated with anti-FLAG agarose gel, then immunoblotted using anti-FLAG mAb (α-FLAG) or anti-HA mAb (α-HA). Also, whole cell extracts (WCE) were analyzed by immunoblotting with the same Abs. Glycogenin (Glyn) was used as a negative control for immunoprecipitation. (C) In vitro autophosphorylation of constitutively active ALK4 and ALK5. Cell lysates from COS-7 cells cotransfected with FLAG-tagged wild-type or P104L mutant caveolin-3 and HA-tagged constitutively active ALK4 (HA-caALK4) or ALK5 (HA-caALK5) were immunoprecipitated with anti-HA agarose. The in vitro kinase reaction was initiated by the addition of kinase reaction buffer and [γ-³²P]ATP. Phosphorylated caALK4 or caALK5 was detected by autoradiography. Immunoprecipitated caALK4, caALK5, and caveolin-3 were analyzed by immunoblotting with anti-HA mAb (α-HA) or anti-FLAG (α-FLAG) mAb. Bands corresponding to phosphorylated type I receptor (in vitro kinase assay), total type I receptor (α-HA), and caveolin-3 (α-FLAG) are shown.