Yap regulates mitochondrial structural remodeling during myoblast differentiation.

Yes-associated protein (Yap) is a core transcriptional coactivator in the downstream Hippo pathway that regulates cell proliferation and tissue growth. However, its role in the regulation of myoblast differentiation remains unclear. Regulation of mitochondrial networks by dynamin-related protein 1 (Drp1) and mitofusion 2 (Mfn2) is crucial for the activation of myoblast differentiation. In the present study, we investigated the interplay between the Hippo/Yap pathway and protein contents of Mfn2 and Drp1 during myoblast differentiation. The Hippo/Yap pathway was inactivated at the early stage of myoblast differentiation due to the decreased ratio of phosphorylated mammalian sterile 20 kinases 1/2 (p-Mst1/2) to Mst1/2, phosphorylated large tumor suppressor 1 (p-Lats1) to Lats1, and phosphorylated Yap (serine 112, p-Yap S112) to Yap, which resulted in the translocation of Yap from cytoplasm to nucleus, increased protein content of Drp1, and mitochondrial fission events. Downregulation of Yap inhibited myoblast differentiation and decreased the content of Drp1, which resulted in elongated mitochondria, fused mitochondrial networks, and collapsed mitochondrial membrane potential. Together, our data indicate that inactivation of the Hippo/Yap pathway could induce mitochondrial fission by promoting Drp1 content at the early stage of myoblast differentiation.