YAP promotes myogenic differentiation via the MEK5‐ERK5 pathway

Abstract

Yes-associated protein (YAP) is a transcriptional coactivator in the Hippo pathway that regulates cell proliferation, differentiation, and apoptosis. The MEK5/ERK5 MAPK cascade is essential for the early step of myogenesis. In this study, we generated C2C12 stable cell lines that expressed YAP (C2C12-YAP cells) and found that ERK5 and MEK5 were activated in C2C12-YAP cells compared with control C2C12 (C2C12-vector) cells. C2C12-YAP stable cells also differentiated into myotubes better than C2C12-vector cells, and expressed elevated levels of myogenin, a transcription factor that regulates myogenesis, as well as elevated levels of myosin heavy chain, a skeletal muscle marker. Western blot analysis revealed that Src and c-Abl (Abelson murine leukemia viral oncogene homolog 1) activation were enhanced in C2C12-YAP cells. Conversely, treatment of inhibitors of c-Abl, Src, or MEK5 inhibited activation of MEK5 and ERK5 and myogenesis of C2C12 myoblasts. Specific interactions between YAP and proteins in the ERK5 pathway, such as MEK kinase 3 (MEKK3) and ERK5, were illustrated by coimmunoprecipitation experiments. MEKK3 contains the PPGY motif (aa 178-181), which may interact with YAP. Site-directed mutagenesis experiments revealed that expression of MEKK3 Y181F mutant inhibited MEK5/ERK5 activation and myogenic differentiation. These results suggest that YAP promotes muscle differentiation by activating the Abl/Src/MEKK3/MEK5/ERK5 kinase cascade.-Chen, T.-H., Chen, C.-Y., Wen, H.-C., Chang, C.-C., Wang, H.-D., Chuu, C.-P., Chang, C.-H. YAP promotes myogenic differentiation the MEK5-ERK5 pathway.

Clinicopathologic significance of nuclear HER4 and phospho-YAP(S127) in human breast cancers and matching brain metastases

“…YAP activity has been linked to stem cell attributes in a range of cancers, including chromosomal instability, E-cadherin loss, mesenchymal features and the induction of SOX9 . 36 , 39 , 40 , 67 – 69 Consistent with this, meta-analysis of previously published data from this cohort 49 , 70 , 71 showed there are direct associations between pYAP(S 127 ) and basal cytokeratins, the mesenchymal marker vimentin, stem cell factors (SOX9, ID1), and markers of chromosomal and mitotic instability (SPAG5, TTK, geminin) ( Figure 4E ).…”

“…Since YAP promotes the phosphorylation and nuclear translocation of ERK5 in myogenesis, 63 we performed IHC analysis of nuclear pERK5 as candidate marker of YAP activity in breast cancer. There were no marked changes in the frequency of unphosphorylated YAP expression according to nuclear pERK5 status, but pYAP(S 127 ), particularly the nuclear pool, was directly associated with nuclear pERK5 ( Figure 4A).…”

Role of YAP/TAZ in Cell Lineage Fate Determination and Related Signaling Pathways

“…Downregulation of YAP inhibits myoblast differentiation by decreasing expression of dynamin-related protein 1 (Drp1), resulting in elongated mitochondria, fused mitochondrial networks, and collapsed mitochondrial membrane potential. Chen et al (2017) implicated the MEK5-ERK5 pathway in early myoblast differentiation mediated by YAP.…”

The Hippo pathway in organ development, homeostasis, and regeneration

“…Recently, YAP/TAZ were reported to promote myogenic differentiation through activating the MEK5/ ERK5 pathway. Overexpression of either YAP or TAZ activated the ERK5 pathway to stimulate C2C12 myoblast differentiation [51]. Mechanistically, YAP and TAZ interact with different components of the ERK5 pathway, with YAP interacting with MEKK3 and ERK5, and TAZ with c-Abl; all of these interactions induce YAP/TAZ nuclear translocation and myogenic differentiation.…”