title: LRP4 induces extracellular matrix productions and facilitates chondrocyte differentiation.
abstract: Endochondral ossification is an essential step for skeletal development, which requires chondrocyte differentiation in growth cartilage. The low-density lipoprotein receptor-related protein 4 (LRP4), a member of LDLR family, is an inhibitor for Wnt signaling, but its roles in chondrocyte differentiation remain to be investigated. Here we found by laser capture microdissection that LRP4 expression was induced during chondrocyte differentiation in growth plate. In order to address the roles, we overexpressed recombinant human LRP4 or knocked down endogenous LRP4 by lentivirus in mouse ATDC5 chondrocyte cells. We found that LRP4 induced gene expressions of extracellular matrix proteins of type II collagen (Col2a1), aggrecan (Acan), and type X collagen (Col10a1), as well as production of total proteoglycans in ATDC5 cells, whereas LRP4 knockdown had opposite effects. Interestingly, LRP4-knockdown reduced mRNA expression of Sox9, a master regulator for chondrogenesis, as well as Dkk1, an extracellular Wnt inhibitor. Analysis of Wnt signaling revealed that LRP4 blocked the Wnt/β-catenin signaling activity in ATDC5 cells. Finally, the reduction of these extracellular matrix productions by LRP4-knockdown was rescued by a β-catenin/TCF inhibitor, suggesting that LRP4 is an important regulator for extracellular matrix productions and chondrocyte differentiation by suppressing Wnt/β-catenin signaling.
authors.affiliation: Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Asai
authors.affiliation: Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Bisei
authors.initials: B
authors.lastname: Ohkawara
authors.affiliation: Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Mikako
authors.initials: M
authors.lastname: Ito
authors.affiliation: Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Masuda
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
authors.affiliation: Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan. Electronic address: ohnok@med.nagoya-u.ac.jp.
authors.forename: Kinji
authors.initials: K
authors.lastname: Ohno
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020219:Chondrogenesis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D006023:Glycoproteins / Q000235:genetics; D006025:Glycosaminoglycans / Q000096:biosynthesis; D006132:Growth Plate / Q000254:growth & development / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D026502:LDL-Receptor Related Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D011794:Quercetin / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D055758:SOX9 Transcription Factor / Q000235:genetics; D060449:Wnt Signaling Pathway / Q000187:drug effects; D051176:beta Catenin / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C495267:CTNNB1 protein, mouse; C501127:Dkk1 protein, mouse; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D006025:Glycosaminoglycans; D036341:Intercellular Signaling Peptides and Proteins; D026502:LDL-Receptor Related Proteins; C551781:LRP4 protein, human; C116415:Lrp4 protein, mouse; D012333:RNA, Messenger; D011973:Receptors, LDL; D011994:Recombinant Proteins; D055758:SOX9 Transcription Factor; C486030:Sost protein, mouse; C527933:Sox9 protein, mouse; D051176:beta Catenin; D011794:Quercetin
keywords: Endochondral ossification; Extracellular matrix production; LRP4; Wnt/β-catenin signaling