title: Global epigenomic analysis indicates protocadherin-7 activates osteoclastogenesis by promoting cell-cell fusion.
abstract: Gene expression is dependent not only on genomic sequences, but also epigenetic control, in which the regulation of chromatin by histone modification plays a crucial role. Histone H3 lysine 4 trimethylation (H3K4me3) and histone H3 lysine 27 trimethylation (H3K27me3) are related to transcriptionally activated and silenced sequences, respectively. Osteoclasts, the multinucleated cells that resorb bone, are generated by the fusion of precursor cells of monocyte/macrophage lineage. To elucidate the molecular and epigenetic regulation of osteoclast differentiation, we performed a chromatin immunoprecipitation sequencing (ChIP-seq) analysis for H3K4me3 and H3K27me3 in combination with RNA sequencing. We focused on the histone modification change from H3K4me3(+)H3K27me3(+) to H3K4me3(+)H3K27me3(-) and identified the protocadherin-7 gene (Pcdh7) to be among the genes epigenetically regulated during osteoclastogenesis. Pcdh7 was induced by RANKL stimulation in an NFAT-dependent manner. The knockdown of Pcdh7 inhibited RANKL-induced osteoclast differentiation due to the impairment of cell-cell fusion, accompanied by a decreased expression of the fusion-related genes Dcstamp, Ocstamp and Atp6v0d2. This study demonstrates that Pcdh7 plays a key role in osteoclastogenesis by promoting cell-cell fusion.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan; Department of Cell Signaling, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Department of Cell Signaling, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8549, Japan; Japan Science and Technology Agency, PRESTO, Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Nakashima
authors.affiliation: Department of Cell Signaling, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8549, Japan; Japan Science and Technology Agency, ERATO, Takayanagi Osteonetwork Project, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Mikihito
authors.initials: M
authors.lastname: Hayashi
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Izawa
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Yasui
authors.affiliation: Genome Science Division, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8904, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Aburatani
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Sakae
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Japan Science and Technology Agency, ERATO, Takayanagi Osteonetwork Project, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: takayana@m.u-tokyo.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takayanagi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D001862:Bone Resorption; D015820:Cadherins / Q000378:metabolism*; D002450:Cell Communication; D047369:Chromatin Immunoprecipitation; D044127:Epigenesis, Genetic; D057890:Epigenomics; D005434:Flow Cytometry; D006657:Histones / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000166:cytology; D008565:Membrane Proteins / Q000378:metabolism; D009000:Monocytes / Q000166:cytology; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism; D000091363:Protocadherins; D053245:RANK Ligand / Q000378:metabolism; D017423:Sequence Analysis, RNA; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015820:Cadherins; D006657:Histones; D008565:Membrane Proteins; D000091363:Protocadherins; D053245:RANK Ligand; D025262:Vacuolar Proton-Translocating ATPases; C501589:DCSTAMP protein, human; C000595081:OCSTAMP protein, human; C113391:PCDH7 protein, human; C545897:ATP6V0D2 protein, human
keywords: Cell–cell fusion; Epigenetics; Osteoclast; Protocadherin-7 (Pcdh7); RANKL