title: Interaction of Tmem119 and the bone morphogenetic protein pathway in the commitment of myoblastic into osteoblastic cells.
abstract: Bone morphogenetic proteins (BMPs) are critical for bone regeneration and induce ectopic bone formation in vivo. The constitutively activating mutation (R206H) of the BMP type 1 receptor, activin A type 1 receptor/activin-like kinase 2 (ACVR1/ALK2), underlies the molecular pathogenesis of fibrodysplasia ossificans progressiva (FOP) in which heterotopic ossification occurs in muscle tissue. In the present study, we performed a comparative DNA microarray analysis between stable empty vector- and ALK2(R206H)-transfected mouse myoblastic C2C12 cells. Forty genes were identified whose expression was increased >3.5 times in the experimental group versus the control. The bone formation-related factor, Tmem119, was included in this group. Osteoblast differentiation markers and mineralization were enhanced in C2C12 cells stably expressing Tmem119. Differentiation of myoblastic cells into myotubes was suppressed but differentiation into chondrocytes was little affected. Transcriptional activity of the BMP-2 signaling molecules, Smad1/5, was increased even in the absence of exogenous BMP-2. Endogenous BMP-2 levels positively correlated with Tmem119 levels. A BMP-2/4 neutralizing antibody and dorsomorphin, an ALK2 inhibitor, antagonized Tmem119-enhanced alkaline phosphatase (ALP) levels. Tmem119 siRNA antagonized the BMP-2-induced ALP and osteocalcin, but not Runx2 and Osterix, mRNAs, in C2C12 cells. In conclusion, Tmem119 levels were increased by the FOP-associated constitutively activating ALK2 mutation in myoblasts. The data show that Tmem119 promotes the differentiation of myoblasts into osteoblasts and the interaction with the BMP signaling pathway likely occurs downstream of Runx2 and Osterix in myoblasts. Tmem119 may play a critical role in the commitment of myoprogenitor cells to the osteoblast lineage.
authors.affiliation: Division of Diabetes, and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan. ken1nai@med.shimane-u.ac.jp
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Tanaka
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Inoue
authors.forename: Geoffrey N
authors.initials: GN
authors.lastname: Hendy
authors.forename: Lucie
authors.initials: L
authors.lastname: Canaff
authors.forename: Takenobu
authors.initials: T
authors.lastname: Katagiri
authors.forename: Riko
authors.initials: R
authors.lastname: Kitazawa
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Komori
authors.forename: Toshitsugu
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Susumu
authors.initials: S
authors.lastname: Seino
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kaji
mesh_terms: D000818:Animals; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
chemical_list: D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D008565:Membrane Proteins; C547179:Obif protein, mouse; D034741:RNA, Small Interfering; D015675:Osteocalcin