Project description:Atherosclerosis is a mechanobiology-related disease that preferentially develops in the aortic arch and arterial branches, which are exposed to disturbed/turbulent blood flow but less in thoracic aorta where the flow pattern is steady laminar flow (LF). Increasing evidence supports that steady LF with high shear stress is protective against atherosclerosis. However, the molecular mechanisms of LF-mediated atheroprotection remain incompletely understood. Hippo/YAP (yes-associated protein) pathway senses and effects mechanical cues and has been reported to be a master regulator of cell proliferation, differentiation, and tissue homeostasis. Here, we show that LF inhibits YAP activity in endothelial cells (ECs). We observed that YAP is highly expressed in mouse EC-enriched tissues (lung and aorta) and in human ECs. Furthermore, we found in apolipoprotein E deficient (ApoE(-/-)) mice and human ECs, LF decreased the level of nuclear YAP protein and YAP target gene expression (connective tissue growth factor and cysteine-rich protein 61) through promoting Hippo kinases LATS1/2-dependent YAP (Serine 127) phosphorylation. Functionally, we revealed that YAP depletion in ECs phenocopying LF responses, reduced the expression of cell cycle gene cyclin A1 (CCNA1) and proinflammatory gene CCL2 (MCP-1). Taken together, we demonstrate that atheroprotective LF inhibits endothelial YAP activation, which may contribute to LF-mediated ECs quiescence and anti-inflammation.
Project description:The highly conserved Hippo signaling pathway is one of the most important pathways involved in tumorigenesis and progress. Previous studies show that YAP, the transcriptional coactivator of Hippo pathway, is expressed highly in many clinical bladder cancer tissues and plays crucial role on bladder cancer progress. To find the YAP-specific target drug and its molecular mechanism in bladder cancer, we apply Verteporfin (VP), a YAP specific inhibitor to function as anti-bladder cancer drug and discover that VP is able to inhibit bladder cancer cell growth and invasion in a dosage dependent manner. Moreover, we demonstrate that VP may inhibit bladder cancer cell growth and invasion via repressing target genes' expression of the Hippo signaling pathway. In further study, we provide evidence that VP is able to inhibit excessive YAP induced bladder cancer cell growth and invasion. To address the repressive function of VP against YAP in bladder cancer, we check the target genes' expression and find VP can dramatically repress YAP overexpression induced Hippo pathway target genes' expression. Taken together, we discover that VP inhibits YAP-induced bladder cancer cell growth and invasion via repressing the target genes' expression of Hippo signaling pathway.
Project description:The adult mammalian heart has limited potential for regeneration. Thus, after injury, cardiomyocytes are permanently lost, and contractility is diminished. In contrast, the neonatal heart can regenerate owing to sustained cardiomyocyte proliferation. Identification of critical regulators of cardiomyocyte proliferation and quiescence represents an important step toward potential regenerative therapies. Yes-associated protein (Yap), a transcriptional cofactor in the Hippo signaling pathway, promotes proliferation of embryonic cardiomyocytes by activating the insulin-like growth factor and Wnt signaling pathways. Here we report that mice bearing mutant alleles of Yap and its paralog WW domain containing transcription regulator 1 (Taz) exhibit gene dosage-dependent cardiac phenotypes, suggesting redundant roles of these Hippo pathway effectors in establishing proper myocyte number and maintaining cardiac function. Cardiac-specific deletion of Yap impedes neonatal heart regeneration, resulting in a default fibrotic response. Conversely, forced expression of a constitutively active form of Yap in the adult heart stimulates cardiac regeneration and improves contractility after myocardial infarction. The regenerative activity of Yap is correlated with its activation of embryonic and proliferative gene programs in cardiomyocytes. These findings identify Yap as an important regulator of cardiac regeneration and provide an experimental entry point to enhance this process.
Project description:Hippo pathway functions as a tumor suppressor pathway by inhibiting the oncogenic potential of pathway effectors YAP/TAZ. However, YAP can also function as a context-dependent tumor suppressor in several types of cancer including clear cell renal cell carcinomas (ccRCC). Here we show that YAP blocks NF-κB signaling in ccRCC to inhibit cancer cell growth. Mechanistically, YAP inhibits the expression of ZHX2, a critical p65 co-factor in ccRCC. Furthermore, YAP competes with ZHX2 for binding to p65. Consequently, elevated nuclear YAP blocks the cooperativity between ZHX2 and p65, leading to diminished NF-κB target gene expression. Pharmacological inhibition of Hippo/MST1/2 blocked NF-κB transcriptional program and suppressed ccRCC cancer cell growth, which can be rescued by ZHX2/p65 overexpression. Our study uncovers a novel crosstalk between the Hippo and NF-κB pathways and its involvement in ccRCC growth inhibition, suggesting that targeting the Hippo pathway may provide a therapeutical opportunity for ccRCC treatment.
Project description:Hippo signaling controls organ size and tumor progression through a conserved pathway leading to nuclear translocation of the transcriptional effector Yki/Yap/Taz. Most of our understanding of Hippo signaling pertains to its cytoplasmic regulation, but how the pathway is controlled in the nucleus remains poorly understood. Here we uncover an evolutionarily conserved mechanism by which CDK7 promotes Yki/Yap/Taz stabilization in the nucleus to sustain Hippo pathway outputs. We found that a modular E3 ubiquitin ligase complex CRL4DCAF12 binds and targets Yki/Yap/Taz for ubiquitination and degradation, whereas CDK7 phosphorylates Yki/Yap/Taz at S169/S128/S90 to inhibit CRL4DCAF12 recruitment, leading to Yki/Yap/Taz stabilization. As a consequence, inactivation of CDK7 reduced organ size and inhibited tumor growth, which could be reversed by restoring Yki/Yap activity. Our study identifies an unanticipated layer of Hippo pathway regulation, defines a novel mechanism by which CDK7 regulates tissue growth, and implies CDK7 as a drug target for Yap/Taz-driven cancer.
Project description:The Hippo pathway regulates organ size and tumorigenesis in Drosophila and mammals and is altered in a variety of human cancers, yet it remains unclear if the Hippo pathway is of prognostic significance to cancer patients. Here we show that the key targets of Hippo signaling, transcriptional coactivators Yki and Yap, play a conserved role in promoting ovarian cancer in flies and humans, respectively. Whereas studies linking Yap to cancer in other tissues have focused on overall Yap levels, we show for the first time that subcellular levels of Yap show an exceptionally strong association with poor patient survival. Specifically, high levels of nuclear Yap (nYap), or low levels of cytoplasmic phosphorylated Yap (cpYap), associated with poor survival from ovarian cancer. Patients with both high nYap and low cpYap had ?50% lower 5-year survival, and this combination is an independent prognostic marker for survival, with an exceptionally high hazard ratio of 7.8. We find that Yap2 is the predominantly expressed Yap isoform in both the ovarian surface epithelium (OSE) and epithelial ovarian cancers. Overexpression of Yap2 and phosphorylation-defective Yap2-5SA in immortalized OSE cells resulted in increased cell proliferation, resistance to cisplatin-induced apoptosis, faster cell migration, and anchorage-independent growth, whereas Yap knockdown resulted in increased sensitivity to cisplatin-induced apoptosis. Findings argue that the Hippo signaling pathway defines an important pathway in progression of ovarian cancer.
Project description:Purpose: The purpose of this study was to investigate the effect of Gomisin G on the transcription level of pancreatic cancer cells SW1990.
Project description:Hippo signaling pathway consists of conserved serine/threonine kinases to maintain optimal organ sizes. Studies have demonstrated that fragmentation of murine ovaries increases actin polymerization and disrupts Hippo signaling, leading to nuclear translocation of Hippo signaling effector Yes-associated protein (YAP) in ovarian follicles and follicle growth. For patients with polycystic ovarian syndrome showing follicle arrest, ovarian wedge resection and laser drilling promote follicle growth. Because these damaging procedures likely involve actin polymerization, we tested whether actin polymerization-promoting drugs could promote YAP translocation and stimulate follicle growth. Treatment of murine ovaries with μM Jasplakinolide (JASP), an actin polymerization-promoting cyclic peptide, or sphingosine-1-phosphate (S1P), a follicular fluid constituent known to promote actin polymerization, increased the conversion of globular actin to the filamentous form, followed by increased nuclear YAP and expression of downstream connective tissue growth factor (CCN2). After short-term treatments with JASP or S1P, in vitro cultured and in vivo grafted ovaries showed follicle growth. Furthermore, induction of constitutively active YAP in ovarian grafts of transgenic mice enhanced follicle development, whereas treatment of human ovarian cortices with JASP or S1P increased CCN2 expression. Thus, JASP and S1P stimulate follicle growth and are potential therapeutic agents for treating polycystic ovarian syndrome and other ovarian disorders.
Project description:We and others have demonstrated that various abnormalities of the bone marrow (BM) mesenchymal stromal cells (MSCs) such as aberrant cytokine expression, abnormal hedgehog signaling, and impaired miRNA biogenesis are observed in patients with acute myeloid leukemia (AML). However, underlying mechanisms to induce the dysfunction of BM MSCs have not yet been clarified. We previously showed that AML cells release abundant exosomal miR-7977, which, in turn, enters BM mesenchymal stromal cells (MSCs). However, the precise function of miR-7977 is not known. In this study, we performed transduction of a miR-7977 mimic into MSCs, compared transcriptomes between control-transduced (n = 3) and miR-7977-transduced MSCs (n = 3), and conducted pathway analysis. The array data revealed that the expression of 0.05% of genes was reduced 2-fold and the expression of 0.01% of genes was increased 2-fold. Interestingly, approximately half of these genes possessed a miR-7977 target site, while the other genes did not, suggesting that miR-7977 regulates the gene expression level directly and indirectly. Gene set enrichment analysis showed that the gene sets of Yes-associated protein 1 (YAP1) _up were significantly enriched (p<0.001, q<0.25), suggesting that miR-7977 modulates the Hippo-YAP signaling pathway. Visualization of pathway and network showed that miR-7977 significantly reduced the expression of Hippo core kinase, STK4. miR-7977 inactivated the Hippo-YAP signaling pathway as proven by GFP-tagged YAP nuclear trans localization and TEAD reporter assay. The miR-7977-transduced MSC cell line, HTS-5, showed elevated saturation density and enhanced entry into the cell cycle. These results suggest that miR-7977 is a critical factor that regulates the Hippo-YAP signaling pathway in BM-MSCs and may be involved in the upregulation of leukemia-supporting stroma growth.
Project description:Yes-associated protein (YAP) is an effector of the Hippo tumor suppressor pathway. The functional significance of YAP in prostate cancer has remained elusive. In this study, we first show that enhanced expression of YAP is able to transform immortalized prostate epithelial cells and promote migration and invasion in both immortalized and cancerous prostate cells. We found that YAP mRNA was upregulated in androgen-insensitive prostate cancer cells (LNCaP-C81 and LNCaP-C4-2 cells) compared to the level in androgen-sensitive LNCaP cells. Importantly, ectopic expression of YAP activated androgen receptor signaling and was sufficient to promote LNCaP cells from an androgen-sensitive state to an androgen-insensitive state in vitro, and YAP conferred castration resistance in vivo. Accordingly, YAP knockdown greatly reduced the rates of migration and invasion of LNCaP-C4-2 cells and under androgen deprivation conditions largely blocked cell division in LNCaP-C4-2 cells. Mechanistically, we found that extracellular signal-regulated kinase-ribosomal s6 kinase signaling was downstream of YAP for cell survival, migration, and invasion in androgen-insensitive cells. Finally, immunohistochemistry showed significant upregulation and hyperactivation of YAP in castration-resistant prostate tumors compared to their levels in hormone-responsive prostate tumors. Together, our results identify YAP to be a novel regulator in prostate cancer cell motility, invasion, and castration-resistant growth and as a potential therapeutic target for metastatic castration-resistant prostate cancer (CRPC).