MLL3 suppresses tumorigenesis through regulating TNS3 enhancer activity [ChIP-seq]

MLL3 is a histone H3K4 methyltransferase which is frequently mutated in cancer, but the underlying molecular mechanisms remain elusive. Here, we found that MLL3 knockout by CRISPR/sgRNA did not elevate proliferation rate of cancer cells, but significantly enhanced cell migration. Through RNA-Seq and ChIP-Seq approaches, we identified TNS3 as the potential target gene for MLL3. MLL3 depletion caused down regulation of H3K4me1 and H3K27ac on an enhancer ~ 8 kb ahead of TNS3. 3C assay indicated the identified enhancer interacts with TNS3 promoter, and repression of enhancer with dCas9-KRAB system impaired TNS3 expression. Exogenous expression of TNS3 in MLL3 deficient cells completely blocked the enhanced cell migration phenotype. Taken together, our study revealed a novel mechanism for MLL3 in suppressing cancer, which may provide novel targets for diagnosis or drug development. Examination of 2 different histone modifications in U2OS cells after MLL3 knockdown.