Project description:Microarray analyses with cells/tissues overexpressing YAP have revealed many transcription targets of YAP (Dong et al, 2007; Zhao et al, 2008). However, as YAP induces transformation of non-cancerous cells, we thought many of known targets of YAP may be indirect consequence of transforming property of YAP. To identify the immediate transcription targets for YAP, we utilized immortalized mammary epithelial MCF-10A cells expressing a tamoxifen inducible, hyperactive (S127/381A) YAP mutant (MCF-10A ERT2-YAP 2SA). MCF-10A ERT2 and MCF-10A ERT2-YAP 2SA are generated. Each cell line was treated with 0.1% of ethanol (solvent) or 1uM of 4-hydroxytamoxifen for 2 or 6 hours. This makes 6 samples per set. The experiments were done in duplicate. The expression data from MCF-10A ERT2 and MCF-10A ERT2-YAP 2SA before tamoxifen treatment can serve as control.
Project description:Hippo effectors YAP/TAZ act as on-off mechanosensing switches by sensing modifications in extracellular matrix (ECM) composition and mechanics. The regulation of their activity has been described so far through a hierarchical model in which elements of Hippo pathway are under the control of Focal Adhesions (FAs). Here we unveiled the molecular mechanism by which cell spreading and RhoA GTPase control FA formation through YAP to stabilize the anchorage of actin cytoskeleton to cell membrane. This mechanism required YAP co-transcriptional function and involved the activation of genes encoding for integrins and FA docking proteins. Tuning YAP transcriptional activity led to the modification of cell mechanics, force development, adhesion strength, determined cell shaping, migration and differentiation. These results provide new insights into the mechanism of YAP mechanosensing activity and qualify Hippo effector as the key determinant of cell mechanics in response to ECM cues.
Project description:The molecular mechanisms by which YAP regulates metastases development were studied using overexpression of mutated forms of YAP able or not to interact with TEAD. Molecular signatures were identified using RNA-sequencing analysis and genes set enrichment.
Project description:Background—YAP, the nuclear effector of Hippo signaling, regulates cellular growth and survival in multiple organs, including the heart, by interacting with TEAD sequence specific DNA-binding proteins. Recent studies showed that YAP stimulates cardiomyocyte proliferation and survival. However, the direct transcriptional targets through which YAP exerts its effects are poorly defined. Methods and Results—To identify genes directly regulated by YAP in cardiomyocytes, we combined differential gene expression analysis in YAP gain- and loss-of-function with genome-wide identification of YAP bound loci using chromatin immunoprecipitation and high throughput sequencing. This screen identified Pik3cb, encoding p110β, a catalytic subunit of phosphoinositol-3-kinase (PI3K), as a candidate YAP effector that promotes cardiomyocyte proliferation and survival. We validated YAP and TEAD occupancy of a conserved enhancer within the first intron of Pik3cb, and show that this enhancer drives YAP-dependent reporter gene expression. Yap gain- and loss-of-function studies indicated that YAP is necessary and sufficient to activate the PI3K-Akt pathway. Like Yap, Pik3cb gain-of-function stimulated cardiomyocyte proliferation, and Pik3cb knockdown dampened the YAP mitogenic activity. Reciprocally, Yap loss-of-function impaired heart function and reduced cardiomyocyte proliferation and survival, all of which were significantly rescued by AAV-mediated Pik3cb expression. Conclusion—Pik3cb is a crucial direct target of YAP, through which the YAP activates PI3K-AKT pathway and regulates cardiomyocyte proliferation and survival. Yap wild type ChIPseq and input
Project description:Regulatory T cells (Tregs) are critical for maintaining self-tolerance and immune homeostasis, but their suppressive function can impede effective anti-tumor immune responses. Foxp3 is a transcription factor expressed in Tregs that is required for their function. The pathways and microenvironmental cues governing Foxp3 expression and Treg function are not completely understood. We found that Yes-associated protein (YAP), a co-activator of the Hippo pathway, is highly expressed in Tregs and bolsters Foxp3 expression and Treg function in vitro and in vivo. To assess how YAP influences patterns of gene expression in Tregs, naïve CD4+ T cells and Tregs were isolated from wild type mice and CD4+ T cell lineage-restricted YAP knockout mice (YAPflox/flox, CD4-Cre+). Gene expression by naïve CD4+ T cells and their resting and stimulated Treg counterparts was analyzed by RNASeq. Our findings reveal that YAP ablation undermines expression of multiple genes involved in the TGFβ/SMAD signaling pathway in Tregs including Activin. These findings suggest that YAP potentiates activity along a pro-Treg signaling axis.