title: Epigenetic Control of Skeletal Development by the Histone Methyltransferase Ezh2.
abstract: Epigenetic control of gene expression is critical for normal fetal development. However, chromatin-related mechanisms that activate bone-specific programs during osteogenesis have remained underexplored. Therefore, we investigated the expression profiles of a large cohort of epigenetic regulators (>300) during osteogenic differentiation of human mesenchymal cells derived from the stromal vascular fraction of adipose tissue (AMSCs). Molecular analyses establish that the polycomb group protein EZH2 (enhancer of zeste homolog 2) is down-regulated during osteoblastic differentiation of AMSCs. Chemical inhibitor and siRNA knockdown studies show that EZH2, a histone methyltransferase that catalyzes trimethylation of histone 3 lysine 27 (H3K27me3), suppresses osteogenic differentiation. Blocking EZH2 activity promotes osteoblast differentiation and suppresses adipogenic differentiation of AMSCs. High throughput RNA sequence (mRNASeq) analysis reveals that EZH2 inhibition stimulates cell cycle inhibitory proteins and enhances the production of extracellular matrix proteins. Conditional genetic loss of Ezh2 in uncommitted mesenchymal cells (Prrx1-Cre) results in multiple defects in skeletal patterning and bone formation, including shortened forelimbs, craniosynostosis, and clinodactyly. Histological analysis and mRNASeq profiling suggest that these effects are attributable to growth plate abnormalities and premature cranial suture closure because of precocious maturation of osteoblasts. We conclude that the epigenetic activity of EZH2 is required for skeletal patterning and development, but EZH2 expression declines during terminal osteoblast differentiation and matrix production.
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: Amel
authors.initials: A
authors.lastname: Dudakovic
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: Emily T
authors.initials: ET
authors.lastname: Camilleri
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: Fuhua
authors.initials: F
authors.lastname: Xu
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Riester
authors.affiliation: the Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, Georgia 30912.
authors.forename: Meghan E
authors.initials: ME
authors.lastname: McGee-Lawrence
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Bradley
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Paradise
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Lewallen
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: Roman
authors.initials: R
authors.lastname: Thaler
authors.affiliation: Medical Genetics and.
authors.forename: David R
authors.initials: DR
authors.lastname: Deyle
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: A Noelle
authors.initials: AN
authors.lastname: Larson
authors.affiliation: From the Departments of Orthopedic Surgery.
authors.forename: David G
authors.initials: DG
authors.lastname: Lewallen
authors.affiliation: the Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota 55905.
authors.forename: Allan B
authors.initials: AB
authors.lastname: Dietz
authors.affiliation: the Department of Biochemistry, University of Vermont Medical School, Burlington, Vermont 05405, and.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Stein
authors.affiliation: the Centro de Investigaciones Biomedicas and Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias Center for Genome Regulation, Universidad Andres Bello, Santiago 837-0146, Chile.
authors.forename: Martin A
authors.initials: MA
authors.lastname: Montecino
authors.affiliation: From the Departments of Orthopedic Surgery, Biochemistry & Molecular Biology.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Westendorf
authors.affiliation: From the Departments of Orthopedic Surgery, Biochemistry & Molecular Biology, vanwijnen.andre@mayo.edu.
authors.forename: Andre J
authors.initials: AJ
authors.lastname: van Wijnen
mesh_terms: D000273:Adipose Tissue / Q000166:cytology; D000818:Animals; D019521:Body Patterning / Q000235:genetics; D001842:Bone and Bones / Q000196:embryology; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D000071221:Enhancer of Zeste Homolog 2 Protein; D044127:Epigenesis, Genetic; D006132:Growth Plate / Q000002:abnormalities; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology; D051379:Mice; D010006:Osteoblasts / Q000166:cytology; D010012:Osteogenesis / Q000235:genetics*; D063151:Polycomb Repressive Complex 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D006657:Histones; D034741:RNA, Small Interfering; D000076983:Histone Methyltransferases; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D011495:Histone-Lysine N-Methyltransferase; D063151:Polycomb Repressive Complex 2
keywords: Ezh2; adipogenesis; bone; epigenetics; histone methylation; mesenchymal stem cells (MSCs); osteoblast; osteogenesis