Mst2 and Lats Kinases Regulate Apoptotic Function of Yes Kinase-associated Protein (YAP)
ABSTRACT The Hippo pathway in Drosophila controls the size and shape of organs. In the fly, activation of this pathway conveys growth-inhibitory signals and promotes apoptosis in epithelial cells. We "reconstituted" the Hippo pathway in a human epithelial cell line and showed that, in contrast to flies, the activation of this pathway results in anti-apoptotic signals. We have shown that in human embryonic kidney (HEK) 293 cells, the complex formation between transcriptional co-activators YAPs (Yes kinase-associated proteins) and Lats kinases requires the intact WW domains of YAPs, as well as intact Pro-Pro-AA-Tyr (where AA is any amino acid) motifs in Lats kinases. These kinases cooperate with the upstream Mst2 kinase to phosphorylate YAPs at Ser-127. Overexpression of YAP2 in HEK293 cells promoted apoptosis, whereas the Mst2/Lats1-induced phosphorylation of YAP partially rescued the cells from apoptotic death. Apoptotic signaling of YAP2 was mediated via stabilization of p73, which formed a complex with YAP2. All components of the Hippo pathway that we studied were localized in the cytoplasm, with the exception of YAP, which also localized in the nucleus. The localization of YAP2 in the nucleus was negatively controlled by the Lats1 kinase. Our apoptotic "readout" of the Hippo pathway in embryonic kidney cells represents a useful experimental system for the identification of the putative upstream receptor, membrane protein, or extracellular factor that initiates an entire signaling cascade and ultimately controls the size of organs.
- SourceAvailable from: Hanna G. Kaspar
[Show abstract] [Hide abstract]
- "The YAP serine 127 to alanine (S127A) mutant is a constitutively active form that remains in the nucleus and is transcriptionally active. YAP regulates the balance between cell proliferation and apoptosis , , , and is amplified in a number of human malignancies including breast, esophageal, hepatocellular, ependymoma, malignant mesothelioma and medulloblastoma , , , , , . In addition, YAP expression correlates with poor prognosis in various cancers, such as colorectal, esophageal, gastric, hepatocellular, lung and ovarian , , , , , , , "
ABSTRACT: Background Yes-associated protein (YAP) is a transcriptional co-activator and regulates cell proliferation and apoptosis. We investigated the clinical and biological significance of YAP in endometrial cancer (EMCA). Methods YAP expression in 150 primary tumor tissues from patients with EMCA was evaluated by immunohistochemistry and its association with clinicopathological data was assessed. The biological functions of YAP were determined in EMCA cell lines through knockdown/overexpression of YAP. The role of YAP in modulating radiation sensitivity was also investigated in EMCA cells. Results Increased nuclear YAP expression was significantly associated with higher grade, stage, lympho-vascular space invasion, postoperative recurrence/metastasis and overall survival in estrogen mediated EMCA, called type 1 cancer (p = 0.019, = 0.028, = 0.0008, = 0.046 and = 0.015, respectively). In multivariate analysis, nuclear YAP expression was confirmed as an independent prognostic factor for overall survival in type 1 EMCA. YAP knockdown by siRNA resulted in a significant decrease in cell proliferation (p<0.05), anchorage-dependent growth (p = 0.015) and migration/invasion (p<0.05), and a significant increase in the number of cells in G0/G1 phase (p = 0.002). Conversely, YAP overexpression promoted cell proliferation. Clonogenic assay demonstrated enhanced radiosensitivity by approximately 36% in YAP inhibited cells. Conclusions Since YAP functions as a transcriptional co-activator, its differential localization in the nucleus of cancer cells and subsequent impact on cell proliferation could have important consequences with respect to its role as an oncogene in EMCA. Nuclear YAP expression could be useful as a prognostic indicator or therapeutic target and predict radiation sensitivity in patients with EMCA.PLoS ONE 06/2014; 9(6):e100974. DOI:10.1371/journal.pone.0100974 · 3.23 Impact Factor
[Show abstract] [Hide abstract]
- "YAP1 has several domains containing a TEAD binding region and 2 WW domains, which are DNA binding domains that function as transcriptional coactivators through interactions with DNA binding transcription factors , , . YAP1 can transactivate growth-promoting genes and enhance p73-dependent apoptosis in response to DNA damage by binding to specific domains , , . Here, for the first time, we show that YAP1 is a direct target of gga-miR-375. "
ABSTRACT: Avian leukosis is a neoplastic disease caused in part by subgroup J avian leukosis virus J (ALV-J). Micro ribonucleic acids (miRNAs) play pivotal oncogenic and tumour-suppressor roles in tumour development and progression. However, little is known about the potential role of miRNAs in avian leukosis tumours. We have found a novel tumour-suppressor miRNA, gga-miR-375, associated with avian leukosis tumorigenesis by miRNA microarray in a previous report. We have also previously studied the biological function of gga-miR-375; Overexpression of gga-miR-375 significantly inhibited DF-1 cell proliferation, and significantly reduced the expression of yes-associated protein 1 (YAP1) by repressing the activity of a luciferase reporter carrying the 3'-untranslated region of YAP1. This indicates that gga-miR-375 is frequently downregulated in avian leukosis by inhibiting cell proliferation through YAP1 oncogene targeting. Overexpression of gga-miR-375 markedly promoted serum starvation induced apoptosis, and there may be the reason why the tumour cycle is so long in the infected chickens. In vivo assays, gga-miR-375 was significantly downregulated in chicken livers 20 days after infection with ALV-J, and YAP1 was significantly upregulated 20 days after ALV-J infection (P<0.05). We also found that expression of cyclin E, an important regulator of cell cycle progression, was significantly upregulated (P<0.05). Drosophila inhibitor of apoptosis protein 1 (DIAP1), which is related to caspase-dependent apoptosis, was also significantly upregulated after infection. Our data suggests that gga-miR-375 may function as a tumour suppressor thereby regulating cancer cell proliferation and it plays a key role in avian leukosis tumorigenesis.PLoS ONE 04/2014; 9(4):e90878. DOI:10.1371/journal.pone.0090878 · 3.23 Impact Factor
[Show abstract] [Hide abstract]
- "The STE20 like kinases MST1 and MST2 are core components of mammalian Hippo signaling pathway, which plays a fundamental role in organ size control and tumor suppression (Avruch et al., 2006; O'Neill and Kolch, 2005; O'Neill et al., 2004; Song et al., 2010). MST1/2 in conjunction with an adaptor protein Salvador phosphorylates and activates LATS1/2 kinases, which in turn associates with adaptor protein MOB1, to phosphorylate and prevent nuclear translocation of the downstream transcription coactivator Yes-associated protein (YAP), and thereby inhibit cell proliferation and promote apoptosis (Oka et al., 2008; Wu et al., 2003). MST1 and MST2 share high sequence homology with identical N-terminal kinase domains for catalysis and distinct C-terminal SARAH (Salvador, RASSF and Hpo homology) domains for homodimerization or hetero-interaction with Salvador and RASSF (Ras association domain family) proteins (Fig. 1A) (Pfeifer et al., 2010; Scheel and Hofmann, 2003). "
ABSTRACT: The STE20 kinases MST1 and MST2 are key players in mammalian Hippo pathway. The SARAH domains of MST1/2 act as a platform to mediate homodimerization and hetero-interaction with a range of adaptors including RASSFs and Salvador, which also possess SARAH domains. Here, we determined the crystal structure of human MST2 SARAH domain, which forms an antiparallel homodimeric coiled coil. Structural comparison indicates that SARAH domains of different proteins may utilize a shared dimerization module to form homodimer or heterodimer. Structure-guided mutational study identified specific interface residues critical for MST2 homodimerization. MST2 mutations disrupting its homodimerization also impaired its hetero-interaction with RAPL (also named RASSF5 and NORE1), which is mediated by their SARAH domains. Further biochemical and cellular assays indicated that SARAH domain-mediated homodimerization and hetero-interaction with RAPL are required for full activation of MST2 and therefore apoptotic functions in T cells.Journal of Structural Biology 01/2014; 186(1). DOI:10.1016/j.jsb.2014.01.008 · 3.23 Impact Factor