Structure And Function Of The Hippo Signaling Pathway Downstream Transcription Factor Complex Of Yap-tead

The Hippo signaling pathway plays an essential role in regulating cell growth, cell proliferation and organ size. YAP, the downstream effector of Hippo signaling pathway, is highly conserved from Drosophila to mammalians. Activation of Hippo signaling initiates a kinase cascade, thereby YAP is phosphorylated by upstream kinase. The phosphorylated YAP supplies a binding site for 14-3-3, and is restrained in cytoplasm. Otherwise, YAP could translocate into nucleus and activate the target genes transcription by binding with transcription factors, like TEAD.YAP is a key regulator of tumorigenesis and a candidate oncogene amplified in human cancers. Amplification of the chromosome region containing the YAP gene has been reported in several human tumor types. There was strong and diffuse nuclear and cytoplasmic YAP expression in colonic adenocarcinoma, lung adenocarcinoma and ovarian serous cystadenocarcinoma.Transcription enhancer factors (TEF/TEAD) is the most important binding partner of YAP in the nucleus. YAP and TEAD physically interact and form a functional transcription complex capable of activating the targeting genes. Although YAP and TEAD play important roles in many cellular aspects, the molecular mechanism of YAP mediated TEAD-dependent transcription remains unknown.,In this thesis, we focus our studies on protein complex of human YAP2 and TEAD1. Molecular biological and biochemistry techniques were used to map their binding interface. The stable complex used for crystallization was assembled in vitro and purified to homogeneity by ion exchange and gel filtration chromatography. The crystal structure of YAP-TEAD complex was solved by SeMet SAD (seleneomethionine single-wavelength anomalous diffraction) and the structure was refined to 2.8 angstrom. In the complex structure, YAP wraps around the globular structure of TEAD and forms extensive interaction via three highly conserved interfaces. We show that the interface three including YAP residues 86-100 is most critical for the complex formation. Our study reveals the biochemical nature of YAP-TEAD interaction and provides a basis for pharmacological intervention of YAP-TEAD hyperactivation in human diseases.