Phosphorylation of Tyr188 in the WW domain of YAP1 plays an essential role in YAP1-induced cellular transformation

Abstract

The Hippo signaling pathway regulates cellular proliferation and survival, thus exerting profound effects on normal cell fate and tumorigenesis. The pivotal effector of this pathway is YAP1, a transcriptional co-activator amplified in mouse and human cancers where it promotes epithelial-tomesenchymal transition (EMT) and malignant transformation. The Hippo tumor suppressor pathway has been suggested to inhibit the YAP1 function through serine phosphorylation-induced cytoplasmic retention and degradation. Here we report that the tyrosine188 (Y188) site of YAP1 isoform with 2 WW domains (known as YAP1-2) plays an important role in YAP1-induced cellular transformation. IP-Mass Spectrometry analysis of YAP1 identified the phosphorylation of Y188 but not other tyrosine residues. In contrast to the aberrant 3D acinus formation observed in YAP1-WT transduced cells, overexpression of YAP1-Y188F (non-phosphorylated mimic) displayed normal 3D structures. In addition, knockdown of the endogenous YAP1 in MDA-MB231 breast cancer cells inhibited cell proliferation and migration, which were then successfully rescued by the exogenous YAP1-WT and YAP1-Y188E but not Y188F. Mechanistically, we also demonstrated that YAP1-Y188F had a higher affinity to the upstream negative regulator PTPN14 and was extensively localized in the cytoplasm. Since the Y188 is located in the conserved aromatic core of the WW domain of YAP1, our finding has a wide implication for WW domain signaling in general, where Y phosphorylation may act as a common positive regulator of the complex formation via WW domains. In summary, our results indicate that tyrosine 188 plays an important role in the YAP1-induced cellular transformation and its phosphorylation may intriguingly serve as a positive indicator of YAP1 activation.

The essential role of YAP O-GlcNAcylation in high-glucose-stimulated liver tumorigenesis

“…reported that phosphorylation of tyrosine188 (Y188) in the YAP1-2 isoform stimulates YAP1-induced cellular transformation. Mutation of Y188 (especially replacement of Y to phenylalanine (F)) leads to a higher affinity of YAP for binding to its upstream negative regulators for cytoplasmic retention 57 . Like Thr241, the Y188 site is also located in the conserved aromatic core of the second WW domain of YAP1.…”

FAK controls the mechanical activation of YAP, a transcriptional regulator required for durotaxis

“…This additionally indicates that canonical signaling is not made redundant by an active mechanical response but that the complex signaling network surrounding YAP needs to remain functional for durotaxis. Multiple kinases are known to directly regulate YAP activity through phosphorylation on residues other than the inactivating Ser 127, which can stabilize transcription complexes that promote particular gene expression profiles (32)(33)(34), opening up the possibility of direct phosphorylation of YAP by FAK.…”

PYK2 negatively regulates the Hippo pathway in TNBC by stabilizing TAZ protein

“…Moreover, Yes phosphorylates YAP, increases its association with TEAD and consequently the activation of Oct3/4 and Nanog 14 , suggesting that tyrosine phosphorylation of YAP and TAZ influences the selectivity of their target genes. Interestingly, a recent study suggests that tyrosine phosphorylation of YAP at Tyr188 (Tyr173 in mouse) within its WW domain affects YAP oncogenic functions, possibly by interfering YAP–LATS1 interactions 42 . We could also detect interaction between LATS1/2 and TAZ by coimmunoprecipitation and found PYK2 in the same immunocomplex (Fig.…”