@article{611b96486bef49cf9d1b6421a809ebf7,
title = "The epigenetic reader Brd4 is required for osteoblast differentiation",
abstract = "Transcription networks and epigenetic mechanisms including DNA methylation, histone modifications, and noncoding RNAs control lineage commitment of multipotent mesenchymal progenitor cells. Proteins that read, write, and erase histone tail modifications curate and interpret the highly intricate histone code. Epigenetic reader proteins that recognize and bind histone marks provide a crucial link between histone modifications and their downstream biological effects. Here, we investigate the role of bromodomain-containing (BRD) proteins, which recognize acetylated histones, during osteogenic differentiation. Using RNA-sequencing (RNA-seq) analysis, we screened for BRD proteins (n = 40) that are robustly expressed in MC3T3 osteoblasts. We focused functional follow-up studies on Brd2 and Brd4 which are highly expressed in MC3T3 preosteoblasts and represent “bromodomain and extra terminal domain” (BET) proteins that are sensitive to pharmacological agents (BET inhibitors). We show that small interfering RNA depletion of Brd4 has stronger inhibitory effects on osteoblast differentiation than Brd2 loss as measured by osteoblast-related gene expression, extracellular matrix deposition, and alkaline phosphatase activity. Similar effects on osteoblast differentiation are seen with the BET inhibitor +JQ1, and this effect is reversible upon its removal indicating that this small molecule has no lasting effects on the differentiation capacity of MC3T3 cells. Mechanistically, we find that Brd4 binds at known Runx2 binding sites in promoters of bone-related genes. Collectively, these findings suggest that Brd4 is recruited to osteoblast-specific genes and may cooperate with bone-related transcription factors to promote osteoblast lineage commitment and maturation.",
keywords = "Brd4, bone, bromodomain, epigenetics, osteoblast",
author = "Paradise, {Christopher R.} and Galvan, {M. Lizeth} and Eva Kubrova and Sierra Bowden and Esther Liu and Carstens, {Mason F.} and Roman Thaler and Stein, {Gary S.} and {van Wijnen}, {Andre J.} and Amel Dudakovic",
note = "Funding Information: We thank our Mayo Clinic colleagues and members of the Orthopedic Research Laboratories, including Drs. Jennifer Westendorf and David Deyle for stimulating discussions and sharing reagents. We also thank Oksana Pichurin for technical support and Marina Ganshina for administrative support. The Genotype-Tissue Expression (GTEx) Project was utilized in our study. We would like to thank the Common Fund of the Office of the Director of the National Institutes of Health, as well as the NCI, NHGRI, NHLBI, NIDA, NIMH, and NINDS for funding and curating this valuable resource. This publication was made possible through an intramural award from the Mayo Clinic (Career Development Award in Orthopedics Research to AD) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (R01 AR069049 to AvW). We also thank William and Karen Eby for generous philanthropic support. Funding Information: We thank our Mayo Clinic colleagues and members of the Orthopedic Research Laboratories, including Drs. Jennifer Westendorf and David Deyle for stimulating discussions and sharing reagents. We also thank Oksana Pichurin for technical support and Marina Ganshina for administrative support. The Genotype‐Tissue Expression (GTEx) Project was utilized in our study. We would like to thank the Common Fund of the Office of the Director of the National Institutes of Health, as well as the NCI, NHGRI, NHLBI, NIDA, NIMH, and NINDS for funding and curating this valuable resource. This publication was made possible through an intramural award from the Mayo Clinic (Career Development Award in Orthopedics Research to AD) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (R01 AR069049 to AvW). We also thank William and Karen Eby for generous philanthropic support. Publisher Copyright: {\textcopyright} 2019 Wiley Periodicals, Inc.",
year = "2020",
month = jun,
day = "1",
doi = "10.1002/jcp.29415",
language = "English (US)",
volume = "235",
pages = "5293--5304",
journal = "Journal of Cellular Physiology",
issn = "0021-9541",
publisher = "Wiley-Liss Inc.",
number = "6",
}