YAP repression of the gene controls hESC differentiation along the cardiac mesoderm lineage.
Estarás Conchi,Hsu Hui-Ting,Huang Ling,Jones Katherine A
Genes & development
Activin/SMAD signaling in human embryonic stem cells (hESCs) ensures expression and stem cell pluripotency. In the presence of Wnt ligand, the Activin/SMAD transcription network switches to cooperate with Wnt/β-catenin and induce mesendodermal (ME) differentiation genes. We show here that the Hippo effector YAP binds to the gene enhancer and prevents the gene from being induced by Activin in proliferating hESCs. ChIP-seq (chromatin immunoprecipitation [ChIP] combined with high-throughput sequencing) data show that YAP impairs SMAD recruitment and the accumulation of P-TEFb-associated RNA polymerase II (RNAPII) C-terminal domain (CTD)-Ser7 phosphorylation at the gene. CRISPR/ knockout of YAP in hESCs enables Activin to induce Wnt3 expression and stabilize β-catenin, which then synergizes with Activin-induced SMADs to activate a subset of ME genes that is required to form cardiac mesoderm. Interestingly, exposure of YAP hESCs to Activin induces cardiac mesoderm markers ( and ) without activating Wnt-dependent cardiac inhibitor genes ( and ). Moreover, canonical Wnt target genes are up-regulated only modestly, if at all, under these conditions. Consequently, YAP-null hESCs exposed to Activin differentiate precisely into beating cardiomyocytes without further treatment. We conclude that YAP maintains hESC pluripotency by preventing expression in response to Activin, thereby blocking a direct route to embryonic cardiac mesoderm formation.
The Hippo pathway effector YAP is a critical regulator of skeletal muscle fibre size.
Watt K I,Turner B J,Hagg A,Zhang X,Davey J R,Qian H,Beyer C,Winbanks C E,Harvey K F,Gregorevic P
The Yes-associated protein (YAP) is a core effector of the Hippo pathway, which regulates proliferation and apoptosis in organ development. YAP function has been extensively characterized in epithelial cells and tissues, but its function in adult skeletal muscle remains poorly defined. Here we show that YAP positively regulates basal skeletal muscle mass and protein synthesis. Mechanistically, we show that YAP regulates muscle mass via interaction with TEAD transcription factors. Furthermore, YAP abundance and activity in muscles is increased following injury or degeneration of motor nerves, as a process to mitigate neurogenic muscle atrophy. Our findings highlight an essential role for YAP as a positive regulator of skeletal muscle size. Further investigation of interventions that promote YAP activity in skeletal muscle might aid the development of therapeutics to combat muscle wasting and neuromuscular disorders.
A functional interaction between Hippo-YAP signalling and FoxO1 mediates the oxidative stress response.
Shao Dan,Zhai Peiyong,Del Re Dominic P,Sciarretta Sebastiano,Yabuta Norikazu,Nojima Hiroshi,Lim Dae-Sik,Pan Duojia,Sadoshima Junichi
The Hippo pathway is an evolutionarily conserved regulator of organ size and tumorigenesis that negatively regulates cell growth and survival. Here we report that Yes-associated protein (YAP), the terminal effector of the Hippo pathway, interacts with FoxO1 in the nucleus of cardiomyocytes, thereby promoting survival. YAP and FoxO1 form a functional complex on the promoters of the catalase and manganese superoxide dismutase (MnSOD) antioxidant genes and stimulate their transcription. Inactivation of YAP, induced by Hippo activation, suppresses FoxO1 activity and decreases antioxidant gene expression, suggesting that Hippo signalling modulates the FoxO1-mediated antioxidant response. In the setting of ischaemia/reperfusion (I/R) in the heart, activation of Hippo antagonizes YAP-FoxO1, leading to enhanced oxidative stress-induced cell death through downregulation of catalase and MnSOD. Conversely, restoration of YAP activity protects against I/R injury. These results suggest that YAP is a nuclear co-factor of FoxO1 and that the Hippo pathway negatively affects cardiomyocyte survival by inhibiting the function of YAP-FoxO1.
A microRNA-Hippo pathway that promotes cardiomyocyte proliferation and cardiac regeneration in mice.
Tian Ying,Liu Ying,Wang Tao,Zhou Ning,Kong Jun,Chen Li,Snitow Melinda,Morley Michael,Li Deqiang,Petrenko Nataliya,Zhou Su,Lu Minmin,Gao Erhe,Koch Walter J,Stewart Kathleen M,Morrisey Edward E
Science translational medicine
In contrast to lower vertebrates, the mammalian heart has limited capacity to regenerate after injury in part due to ineffective reactivation of cardiomyocyte proliferation. We show that the microRNA cluster miR302-367 is important for cardiomyocyte proliferation during development and is sufficient to induce cardiomyocyte proliferation in the adult and promote cardiac regeneration. In mice, loss of miR302-367 led to decreased cardiomyocyte proliferation during development. In contrast, increased miR302-367 expression led to a profound increase in cardiomyocyte proliferation, in part through repression of the Hippo signal transduction pathway. Postnatal reexpression of miR302-367 reactivated the cell cycle in cardiomyocytes, resulting in reduced scar formation after experimental myocardial infarction. However, long-term expression of miR302-367 induced cardiomyocyte dedifferentiation and dysfunction, suggesting that persistent reactivation of the cell cycle in postnatal cardiomyocytes is not desirable. This limitation can be overcome by transient systemic application of miR302-367 mimics, leading to increased cardiomyocyte proliferation and mass, decreased fibrosis, and improved function after injury. Our data demonstrate the ability of microRNA-based therapeutic approaches to promote mammalian cardiac repair and regeneration through the transient activation of cardiomyocyte proliferation.
Hippo pathway inhibits Wnt signaling to restrain cardiomyocyte proliferation and heart size.
Heallen Todd,Zhang Min,Wang Jun,Bonilla-Claudio Margarita,Klysik Ela,Johnson Randy L,Martin James F
Science (New York, N.Y.)
Genetic regulation of mammalian heart size is poorly understood. Hippo signaling represents an organ-size control pathway in Drosophila, where it also inhibits cell proliferation and promotes apoptosis in imaginal discs. To determine whether Hippo signaling controls mammalian heart size, we inactivated Hippo pathway components in the developing mouse heart. Hippo-deficient embryos had overgrown hearts with elevated cardiomyocyte proliferation. Gene expression profiling and chromatin immunoprecipitation revealed that Hippo signaling negatively regulates a subset of Wnt target genes. Genetic interaction studies indicated that β-catenin heterozygosity suppressed the Hippo cardiomyocyte overgrowth phenotype. Furthermore, the Hippo effector Yap interacts with β-catenin on Sox2 and Snai2 genes. These data uncover a nuclear interaction between Hippo and Wnt signaling that restricts cardiomyocyte proliferation and controls heart size.