title: The Hippo pathway member Yap plays a key role in influencing fate decisions in muscle satellite cells.
abstract: Satellite cells are the resident stem cells of skeletal muscle. Mitotically quiescent in mature muscle, they can be activated to proliferate and generate myoblasts to supply further myonuclei to hypertrophying or regenerating muscle fibres, or self-renew to maintain the resident stem cell pool. Here, we identify the transcriptional co-factor Yap as a novel regulator of satellite cell fate decisions. Yap expression increases during satellite cell activation and Yap remains highly expressed until after the differentiation versus self-renewal decision is made. Constitutive expression of Yap maintains Pax7(+) and MyoD(+) satellite cells and satellite cell-derived myoblasts, promotes proliferation but prevents differentiation. In contrast, Yap knockdown reduces the proliferation of satellite cell-derived myoblasts by ≈40%. Consistent with the cellular phenotype, microarrays show that Yap increases expression of genes associated with Yap inhibition, the cell cycle, ribosome biogenesis and that it represses several genes associated with angiotensin signalling. We also identify known regulators of satellite cell function such as BMP4, CD34 and Myf6 (Mrf4) as genes whose expression is dependent on Yap activity. Finally, we confirm in myoblasts that Yap binds to Tead transcription factors and co-activates MCAT elements which are enriched in the proximal promoters of Yap-responsive genes.
authors.affiliation: School of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, UK.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Judson
authors.forename: Annie M
authors.initials: AM
authors.lastname: Tremblay
authors.forename: Paul
authors.initials: P
authors.lastname: Knopp
authors.forename: Robert B
authors.initials: RB
authors.lastname: White
authors.forename: Roby
authors.initials: R
authors.lastname: Urcia
authors.forename: Cosimo
authors.initials: C
authors.lastname: De Bari
authors.forename: Peter S
authors.initials: PS
authors.lastname: Zammit
authors.forename: Fernando D
authors.initials: FD
authors.lastname: Camargo
authors.forename: Henning
authors.initials: H
authors.lastname: Wackerhage
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D018797:Cell Cycle Proteins; D048708:Cell Growth Processes / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D002642:Chick Embryo; D000090683:Hippo Signaling Pathway; D006736:Horses; D051379:Mice; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology* / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D000091102:YAP-Signaling Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D010750:Phosphoproteins; D000091102:YAP-Signaling Proteins; C486223:Yap1 protein, mouse; D017346:Protein Serine-Threonine Kinases