Project description:YAP and TAZ are transcriptional co-activators and downstream effectors of the Hippo pathway, which play crucial roles in organ size control and cancer pathogenesis. Genetic deletion of YAP/TAZ has revealed their critical importance for embryonic development of the heart, vasculature and gastrointestinal mesenchyme. The aim of this study was to determine the long term role of YAP/TAZ in adult vascular smooth muscle in vivo. We used the novel Itga8-CreERT2 mouse for deletion of YAP/TAZ (i8-Y/T-KO).
Project description:We conditionally knocked out both Yap and Taz in cranial neural crest (CNC) using the Wnt1Cre driver and sequenced mRNA from embryonic day 10.5 mandibles. Examination of mRNA level in E10.5 mandibular tissues from control and Wnt1Cre Taz and Yap dKO mutant.
Project description:Inadequate adaption to mechanical forces, including an elevated blood pressure, contributes to the development of arterial aneurysms. Recent studies have pointed to a mechano-protective role of YAP and TAZ in vascular smooth muscle cells (SMCs). Here, we created vascular SMC-specific knockouts (KOs) of YAP and TAZ using integrin-alpha8-Cre mice (i8-YT-KO). I8-YT-KO mice spontaneously developed aneurysms in the abdominal aorta within two weeks of knockout induction. Loss of YAP expression was also observed in human aortic aneurysms. I8-YT-KO mice developed vascular lesions in other arteries at later times, but the gastrointestinal tract was spared. Aneurysms were characterized by elastin disarray, SMC apoptosis, and accumulation of proteoglycans and inflammatory cells, including macrophages and neutrophils. RNA-sequencing, proteomics, and myography demonstrated decreased contractile differentiation of SMCs and impaired vascular contractility. This associated with partial loss of vascular myocardin expression, reduced blood pressure, and edema. Mediators in the cGAS-STING pathway, which sparks inflammation in response to double-stranded DNA, were increased in aortic lysates. A sizeable increase of the transcription factor Sox9, along with several direct target genes, including aggrecan (Acan), contributed to proteoglycan accumulation. This was the earliest detectable change, occurring three days after knockout induction, and before the pro-inflammatory transition. In conclusion, Itga8-Cre deletion of YAP and TAZ represents a rapid and spontaneous aneurysm model that re-capitulates features of human abdominal aortic aneurysms.
Project description:Angiogenesis, the process by which endothelial cells (ECs) form new blood vessels from existing ones, is intimately linked to the tissue's metabolic milieu and often occurs at nutrient-deficient sites. However, ECs rely on sufficient metabolic resources to support growth and proliferation. How endothelial nutrient acquisition and usage are regulated is unknown. Here we show that these processes are dictated by YAP/TAZ-TEAD – a transcriptional module whose function is highly responsive to changes in the tissue environment. ECs lacking YAP/TAZ or their transcriptional partners, TEAD1, 2, and 4 fail to divide, resulting in stunted vascular growth in mice. Conversely, activation of TAZ, the more abundant paralogue in ECs, boosts proliferation, leading to vascular hyperplasia. We find that YAP/TAZ promote angiogenesis by fueling nutrient mTORC1 signaling. By orchestrating the transcription of a repertoire of cell-surface transporters, YAP/TAZ-TEAD stimulate the import of amino acids and other essential nutrients, thereby enabling mTORC1 pathway activation. Dissociating mTORC1 from these nutrient inputs – elicited by the loss of Rag GTPases – inhibits mTORC1 activity and prevents YAP/TAZ-dependent vascular growth. These findings define a pivotal role for YAP/TAZ-TEAD in steering endothelial mTORC1 and illustrate the essentiality of coordinated nutrient fluxes in the vasculature.
Project description:The Hippo pathway downstream effectors, Yap and Taz, play key roles in cell proliferation and tissue growth, regulating gene expression especially via interaction with Tead transcription factors. To investigate their role in skeletal muscle stem cells, we analysed gene expression changes driven by Taz and compared these to Yap mediated changes to the transcriptome by measurement of gene expression on Affymetrix microarrays. To interrogate overlapping and unique transcriptional changes driven by these Hippo effectors, satellite cell-derived myoblasts were transduced with constitutively active TAZ S89A or YAP S127A retrovirus for 24h or 48h, with empty retrovirus as control. Triplicate microarray analyses of empty vector controls, hYAP1 S127A and TAZ S89A transgenic primary myoblasts were conducted.
Project description:Abstract Hippo pathway downstream effectors Yap and Taz play key roles in cell proliferation and regeneration, regulating gene expression especially via interaction with Tead transcription factors. To investigate their role in skeletal muscle stem cells, we analysed Taz in vivo and ex vivo in comparison to Yap. Taz was expressed in activated satellite cells. siRNA knockdown or constitutive expression of wildtype or constitutively active TAZ mutants showed that TAZ promoted proliferation, a function that was shared with YAP. However, at later stages of myogenesis, TAZ also enhanced myogenic differentiation of myoblasts, whereas YAP inhibits such differentiation. Functionally, while muscle growth was mildly affected in Taz (gene symbol Wwtr1-/-) knockout mice, there were no overt effect on regeneration. However, conditional knockout of Yap in satellite cells of Pax7Cre-ERT2/+ : Yapflox/flox : Rosa26Lacz mice produced a marked regeneration deficit. To identify potential mechanisms, microarray analysis showed many common Taz/Yap targets, but Taz also regulates some genes independently of Yap, including myogenic genes such as Pax7, Myf5 and Myod1. Proteomic analysis of Yap/Taz revealed many common binding partners, but Taz also interacts with proteins distinct from Yap, that are mainly involved in myogenesis and aspects of cytoskeleton organization. Neither TAZ nor YAP bind members of the Wnt destruction complex but both extensively changed expression of Wnt and Wnt-cross talking genes with known roles in myogenesis. Finally, TAZ operates through Tead4 to enhance myogenic differentiation. In summary, Taz and Yap have overlapping functions in promoting myoblast proliferation but Taz then switches to promote myogenic differentiation.
Project description:The optic vesicle comprises a pool of bi-potential progenitor cells from which the retinal pigment epithelium (RPE) and neural retina fates segregate during ocular morphogenesis. Several transcription factors and signaling pathways have been shown to be important for RPE maintenance and differentiation, but an understanding of the initial fate specification and determination of this ocular cell type is lacking. We show that Yap/Taz-Tead activity is necessary and sufficient for optic vesicle progenitors to adopt RPE identity in zebrafish. A Teadresponsive transgene is expressed within the domain of the optic cup from which RPE arises, and Yap immunoreactivity localizes to the nuclei of prospective RPE cells. yap (yap1) mutants lack a subset of RPE cells and/or exhibit coloboma. Loss of RPE in yap mutants is exacerbated in combination with taz (wwtr1) mutant alleles such that, when Yap and Taz are both absent, optic vesicle progenitor cells completely lose their ability to form RPE. The mechanism of Yap dependent RPE cell type determination is reliant on both nuclear localization of Yap and interaction with a Tead co-factor. In contrast to loss of Yap and Taz, overexpression of either protein within optic vesicle progenitors leads to ectopic pigmentation in a dosagedependent manner. Overall, this study identifies Yap and Taz as key early regulators of RPE genesis and provides a mechanistic framework for understanding the congenital ocular defects of Sveinsson’s chorioretinal atrophy and congenital retinal coloboma. 60 pooled eyes from 36 hpf wild type or vsx2:Gal4/dsRed:14xUAS:YapS87A embryos were pooled for one sample. Three wild type and three vsx2:Gal4/dsRed:14xUAS:YapS87A pools were analyzed for RNA.
Project description:Phosphodiesterase type 5 inhibitors (PDE5is) are the primary therapeutic option for erectile dysfunction. However, 30% of patients do not respond to PDE5is treatment, making the quest for a new treatment modality a central endeavor. Here, we found a new pathway in erectile function control, mechano-regulated YAP/TAZ activate Adrenomedullin transcription, which sustains smooth muscle cells (SMCs) relaxation to maintain the erection. We first found that penile erection stretches the SMCs, dominating YAP/TAZ activity. Subsequently, we showed that YAP/TAZ plays a vital role in erectile function and penile rehabilitation using genetic lesions and several animal models. The mechanism relies on the regulation of Adrenomedullin on penile SMCs contraction, which we identify here as a direct YAP/TAZ transcript. Notably, conventional PDE5is targeting NO-cGMP signaling do not cure YAP/TAZ deficient ED. In contrast, by activating YAP/TAZ-Adrenomedullin cascade, mechano-stimulation improved erectile function, including PDE5is non-responders in both experimental models and clinical trials. Our studies lay the groundwork for exploring mechano-YAP/TAZ-Adrenomedullin as prospective targets in the treatment of ED