Journal article
Disruption of cardiac Med1 inhibits RNA polymerase II promoter occupancy and promotes chromatin remodeling
American journal of physiology. Heart and circulatory physiology, Vol.316(2), pp.H314-H325
02/01/2019
DOI: 10.1152/ajpheart.00580.2018
PMCID: PMC6397381
PMID: 30461303
Abstract
The Mediator coactivator complex directs gene-specific expression by binding distal enhancer-bound transcription factors through its Med1 subunit while bridging to RNA polymerase II (Pol II) at gene promoters. In addition, Mediator scaffolds epigenetic modifying enzymes that determine local DNA accessibility. Previously, we found that deletion of Med1 in cardiomyocytes deregulates more than 5,000 genes and promotes acute heart failure. Therefore, we hypothesized that Med1 deficiency disrupts enhancer-promoter coupling. Using chromatin immunoprecipitation-coupled deep sequencing (ChIP-seq; n = 3/ChIP assay), we found that the Pol II pausing index is increased in Med1 knockout versus floxed control mouse hearts primarily due to a decrease in Pol II occupancy at the majority of transcriptional start sites without a corresponding increase in elongating species. Parallel ChIP-seq assays reveal that Med1-dependent gene expression correlates strongly with histone H3 K27 acetylation, which is indicative of open and active chromatin at transcriptional start sites, whereas H3 K27 trimethylated levels, representing condensed and repressed DNA, are broadly increased and inversely correlate with absolute expression levels. Furthermore, Med1 deletion leads to dynamic changes in acetyl-K27 associated superenhancer regions and their enriched transcription factor-binding motifs that are consistent with altered gene expression. Our findings suggest that Med1 is important in establishing enhancer-promoter coupling in the heart and supports the proposed role of Mediator in establishing preinitiation complex formation. We also found that Med1 determines chromatin accessibility within genes and enhancer regions and propose that the composition of transcription factors associated with superenhancer changes to direct gene-specific expression. NEW & NOTEWORTHY Based on our previous findings that transcriptional homeostasis and cardiac function are disturbed by cardiomyocyte deletion of the Mediator coactivator Med1 subunit, we investigated potential underlying changes in RNA polymerase II localization and global chromatin accessibility. Using chromatin immunoprecipitation sequencing, we found that disrupted transcription arises from a deficit in RNA polymerase II recruitment to gene promoters. Furthermore, active versus repressive chromatin marks are redistributed within gene loci and at enhancer regions correlated with gene expression changes.
Details
- Title: Subtitle
- Disruption of cardiac Med1 inhibits RNA polymerase II promoter occupancy and promotes chromatin remodeling
- Creators
- Duane D Hall - Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine , Iowa City, IowaKathryn M Spitler - Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine , Iowa City, IowaChad E Grueter - Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine , Iowa City, Iowa
- Resource Type
- Journal article
- Publication Details
- American journal of physiology. Heart and circulatory physiology, Vol.316(2), pp.H314-H325
- DOI
- 10.1152/ajpheart.00580.2018
- PMID
- 30461303
- PMCID
- PMC6397381
- NLM abbreviation
- Am J Physiol Heart Circ Physiol
- ISSN
- 0363-6135
- eISSN
- 1522-1539
- Grant note
- R01 HL125436 / NHLBI NIH HHS
- Language
- English
- Date published
- 02/01/2019
- Academic Unit
- Cardiovascular Medicine; Craniofacial Anomalies Research Center; Biochemistry and Molecular Biology; Health, Sport, and Human Physiology ; Internal Medicine
- Record Identifier
- 9984094534902771
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