Study of the Mechanism Underlying the Regulation of the Alternative Splicing of YAP1 pre-mRNA in Human Cancer Cell Lines

The Yes-associated protein (YAP) is a transcription coactivator that plays crucial roles in organ size control and tumorigenesis, and was demonstrated to be inhibited by the Hippo signaling pathway. Elevated YAP expression and nuclear localization have been observed in multiple types of human cancers. Moreover, YAP is also shown to be essential for the maintenance of pluripotency of the embryonic stem cells. To date, the molecular mechanisms regulating the expression of YAP in human cancer cells remain unknown. In our preliminary study, we found that the YAP 3′ untranslated region (3′ UTR) was alternatively spliced to generate a novel 950 bp 3′UTR mRNA from the full length 3′UTR region (3483 bp) of the YAP mRNA in human cancer cells. The ratio of alternatively spliced 3′ UTR YAP mRNA to full length 3′UTR YAP mRNA was down-regulated by exposure of the cells to PKC inhibitor chelerythrine chloride.Further study found that the activity of GAPDH promoter driven luciferase reporter assay with alternatively spliced 3′ UTR is much lower compared with reporter constructed mRNA with full length 3′ UTR, suggesting that alternatively spliced 3′UTR, YAP mRNA may have a shorter half-life than full length 3′UTR mRNA. In this proposal, we intend to investigate the role of alternative splicing in the YAP gene expression. Understanding the regulation of YAP expression would provide further insights into the regulation of HIPPO pathway activity and mechanisms underlying the maintenance of human embryonic stem cell phenotype and tumorigenesis. We plan to further determine the stability the alternatively spliced 3′ UTR YAP mRNA in human cancer cell lines. We will then analyze the role of cis-acting RNA splicing elements of the YAP 3’UTR on YAP expression. Whether over-expression or knockdown of splicing factors, such as hnRNPs, may affect YAP 3’UTR alternative splicing and YAP expression will also be assessed

Project ID:PC10308-0611
External Project ID:MOST103-2320-B182-009