ABSTRACT
The transcriptional co-activator Yes-associated protein (YAP) has been implicated as an oncogene and is found to promote breast cancer metastasis. However, the pro-metastatic mechanism of YAP remains unclear. Here, we demonstrated that YAP functions as a transcriptional repressor of growth differentiation factor-15 (GDF15), a divergent member of the transforming growth factor superfamily, in several breast cancer cell lines. Functionally, knockdown of YAP decreased, whereas knockdown of GDF15 increased, the metastatic potential of breast cancer cells. More than that, the reduced metastasis in YAP-depleted cells could be reversed by simultaneous knockdown of GDF15. Mechanistically, the repressive effect of YAP on GDF15 requires its transcriptional factor TEAD (TEA domain family). In addition, YAP recruits polycomb repressive complex 2 (PRC2) to tri-methylate histone H3 lysine 27 in the promoter region of GDF15. Co-immunoprecipitation experiments demonstrated that YAP and enhancer of zeste 2 PRC2 subunit (EZH2) physically interact with each other. In conclusion, our data reveal that YAP promotes metastasis of breast cancer cells by repressing GDF15 transcription and present a novel molecular mechanism underlying the pro-metastasis function of YAP oncoprotein, with the implication of a therapeutic avenue for breast cancer treatment.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Breast Neoplasms/metabolism , Gene Expression Regulation, Neoplastic , Growth Differentiation Factor 15/biosynthesis , Phosphoproteins/metabolism , Transcription, Genetic , Adaptor Proteins, Signal Transducing/genetics , Animals , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Enhancer of Zeste Homolog 2 Protein/genetics , Enhancer of Zeste Homolog 2 Protein/metabolism , Female , Growth Differentiation Factor 15/genetics , Humans , Mice , Neoplasm Metastasis , Phosphoproteins/genetics , Polycomb Repressive Complex 2/genetics , Polycomb Repressive Complex 2/metabolism , Transcription Factors , YAP-Signaling ProteinsABSTRACT
The Hippo signaling pathway plays a critical role in body development and tissue growth. As the core effector of the Hippo signaling pathway, Yes-associated protein (YAP) has been reported to be involved in various kinds of human cancers. However, the mechanism for the regulation of YAP activity has not been completely understood. In this study, we constructed a YAP Thr425Ala mutant and found that this mutation decreased YAP transcriptional activity. Further, T425A retained YAP in the cytoplasm without affecting the phosphorylation of YAP S127. Moreover, we observed that the T425A mutation attenuated the ability of YAP in driving MCF10A cell migration. Our research indicates that T425 of YAP is important for the regulation of YAP localization and activity.
Subject(s)
Mutation , Nuclear Proteins/genetics , Transcription Factors/genetics , Cell Cycle Proteins , Cell Movement , HEK293 Cells , Humans , MCF-7 Cells , Nuclear Proteins/physiology , Phosphorylation , Transcription Factors/physiologyABSTRACT
E2F1 and FOXO3 are two transcription factors that have been shown to participate in cellular senescence. Previous report reveals that E2F1 enhanced cellular senescence in human fibroblast cells, while FOXO transcription factors play against senescence by regulation reactive oxygen species scavenging proteins. However, their functional interplay has been unclear. Here we use E2F1 knock-out murine Embryonic fibroblasts (MEFs), knockdown RNAi constructs, and ectopic expression of E2F1 to show that it functions by negatively regulating FOXO3. E2F1 attenuates FOXO3-mediated expression of MnSOD and Catalase without affecting FOXO3 protein stability, subcellular localization, or phosphorylation by Akt. We mapped the interaction between E2F1 and FOXO3 to a region including the DNA binding domain of E2F1 and the C-terminal transcription-activation domain of FOXO3. We propose that E2F1 inhibits FOXO3-dependent transcription by directly binding FOXO3 in the nucleus and preventing activation of its target genes. Moreover, knockdown of the Caenorhabditis elegans E2F1 ortholog efl-1 significantly extends lifespan in a manner that requires the activity of the C. elegans FOXO gene daf-16. We conclude that there is an evolutionarily conserved signaling connection between E2F1 and FOXO3, which regulates cellular senescence and aging by regulating the activity of FOXO3. We speculate that drugs and/or therapies that inhibit this physical interaction might be good candidates for reducing cellular senescence and increasing longevity.
