MCRIP1, an ERK substrate, mediates ERK-induced gene silencing during epithelial-mesenchymal transition by regulating the co-repressor CtBP.

The ERK pathway not only upregulates growth-promoting genes, but also downregulates anti-proliferative and tumor-suppressive genes. In particular, ERK signaling contributes to repression of the E-cadherin gene during epithelial-mesenchymal transition (EMT). The CtBP transcriptional co-repressor is also involved in gene silencing of E-cadherin. However, the functional relationship between ERK signaling and CtBP is unknown. Here, we identified an ERK substrate, designated MCRIP1, which bridges ERK signaling and CtBP-mediated gene silencing. CtBP is recruited to promoter elements of target genes by interacting with the DNA-binding transcriptional repressor ZEB1. We found that MCRIP1 binds to CtBP, thereby competitively inhibiting CtBP-ZEB1 interaction. When phosphorylated by ERK, MCRIP1 dissociates from CtBP, allowing CtBP to interact with ZEB1. In this manner, the CtBP co-repressor complex is recruited to, and silences, the E-cadherin promoter by inducing chromatin modifications. Our findings reveal a molecular mechanism underlying ERK-induced epigenetic gene silencing during EMT and its dysregulation in cancer.