Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

The MLL3/MLL4 branch of the COMPASS family regulates H3K4 monomethylation at enhancers

ABSTRACT: Histone H3 lysine 4 (H3K4) can be mono-, di-, and trimethylated by members of the COMPASS (COMplex of Proteins ASsociated with Set1) family from yeast to human and these modifications can be found at distinct regions of the genome. Monomethylation of histone H3K4 (H3K4me1) is relatively more enriched at metazoan enhancer regions compared to trimethylated histone H3K4 (H3K4me3), which are found at transcription start sites in all eukaryotes. Our recent studies in Drosophila demonstrated that the Trithorax-related (Trr) branch of the COMPASS family regulates enhancer activity and is responsible for the implementation of H3K4me1 at these regions. There are six COMPASS family members in mammals, two of which, MLL3 and MLL4, are most closely related to Drosophila Trr. Here, we use ChIP-seq of this class of COMPASS family members in both human HCT116 cells and mouse embryonic stem cells and find that MLL4 is preferentially found at enhancer regions. MLL3 and MLL4 are frequently mutated in cancer, and indeed, the widely used HCT116 cancer cell line contains inactivating mutations in the MLL3 gene. Using HCT116 cells in which MLL4 has also been knocked out, we demonstrate that MLL4 is a major regulator of H3K4me1 in these cells, with the greatest loss of monomethylation at enhancer regions. Moreover, we found a redundant role between Mll3 and Mll4 in enhancer H3K4 monomethylation in mouse embryonic fibroblast (MEF) cells. These findings suggest that mammalian MLL3/MLL4 function in the regulation of enhancer activity and enhancer-promoter communication during gene expression and that mutations of MLL3 and MLL4 found in cancer could exert their properties through enhancer malfunction. ChIP-Seq in mouse embryonic stem (mES) cells for MLL4. ChIP-seq of MLL4 and p300 in human parental HCT116 cells. ChIP-seq of H3K4me1, H3K4me2 and H3K4me3 in parental HCT116 cells and HCT116 cells with Mll4∆set.

ORGANISM(S): Homo sapiens

SUBMITTER: Xin Gao

PROVIDER: E-GEOD-51176 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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The MLL3/MLL4 branches of the COMPASS family function as major histone H3K4 monomethylases at enhancers.

Hu Deqing D Gao Xin X Morgan Marc A MA Herz Hans-Martin HM Smith Edwin R ER Shilatifard Ali A

Molecular and cellular biology 20130930 23

Histone H3 lysine 4 (H3K4) can be mono-, di-, and trimethylated by members of the COMPASS (complex of proteins associated with Set1) family from Saccharomyces cerevisiae to humans, and these modifications can be found at distinct regions of the genome. Monomethylation of histone H3K4 (H3K4me1) is relatively more enriched at metazoan enhancer regions compared to trimethylated histone H3K4 (H3K4me3), which is enriched at transcription start sites in all eukaryotes. Our recent studies of Drosophila ...[more]

PMID: 24081332

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Project description:FOXA1 is a pioneer factor that is important in hormone dependent cancer cells to stabilise nuclear receptors, such as estrogen receptor (ER) to chromatin. FOXA1 binds to enhancers regions that are enriched in H3K4mono- and dimethylation (H3K4me1, H3K4me2) histone marks and evidence suggests that these marks are requisite events for FOXA1 to associate with enhancers to initate subsequent gene expression events. However, exogenous expression of FOXA1 has been shown to induce H3K4me1 and H3K4me2 signal at enhancer elements and the order of events and the functional importance of these events is not clear. We performed a FOXA1 Rapid Immunoprecipitation Mass Spectrometry of Endogenous Proteins (RIME) screen in ERα-positive MCF-7 breast cancer cells in order to identify FOXA1 interacting partners and we found histone-lysine N-methyltransferase (MLL3) as the top FOXA1 interacting protein. MLL3 is typically thought to induce H3K4me3 at promoter regions, but recent findings suggest it may contribute to H3K4me1 deposition, in line with our observation that MLL3 associates with an enhancer specific protein. We performed MLL3 ChIP-seq in breast cancer cells and unexpectedly found that MLL3 binds mostly at non-promoter regions enhancers, in contrast to the prevailing hypothesis. MLL3 was shown to occupy regions marked by FOXA1 occupancy and as expected, H3K4me1 and H3K4me2. MLL3 binding was dependent on FOXA1, indicating that FOXA1 recruits MLL3 to chromatin. Motif analysis and subsequent genomic mapping revealed a role for Grainy head like protein-2 (GRHL2) which was shown to co-occupy regions of the chromatin with MLL3. Regions occupied by all three factors, namely FOXA1, MLL3 and GRHL2, were most enriched in H3K4me1. MLL3 silencing decreased H3K4me1 at enhancer elements, but had no appreciable impact on H3K4me3 at enhancer elements. We identify a complex relationship between FOXA1, MLL3 and H3K4me1 at enhancers in breast cancer and propose a mechanism whereby the pioneer factor FOXA1 can interact with a chromatin modifier MLL3, recruiting it to chromatin to facilitate the deposition of H3K4me1 histone marks, subsequently demarcating active enhancer elements.

Dataset Information

The MLL3/MLL4 branch of the COMPASS family regulates H3K4 monomethylation at enhancers

Publications

The MLL3/MLL4 branches of the COMPASS family function as major histone H3K4 monomethylases at enhancers.

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