title: Core binding factor beta (Cbfβ) controls the balance of chondrocyte proliferation and differentiation by upregulating Indian hedgehog (Ihh) expression and inhibiting parathyroid hormone-related protein receptor (PPR) expression in postnatal cartilage and bone formation.
abstract: Core binding factor beta (Cbfβ) is essential for embryonic bone morphogenesis. Yet the mechanisms by which Cbfβ regulates chondrocyte proliferation and differentiation as well as postnatal cartilage and bone formation remain unclear. Hence, using paired-related homeobox transcription factor 1-Cre (Prx1-Cre) mice, mesenchymal stem cell-specific Cbfβ-deficient (Cbfβ(f/f) Prx1-Cre) mice were generated to study the role of Cbfβ in postnatal cartilage and bone development. These mutant mice survived to adulthood but exhibited severe sternum and limb malformations. Sternum ossification was largely delayed in the Cbfβ(f/f) Prx1-Cre mice and the xiphoid process was noncalcified and enlarged. In newborn and 7-day-old Cbfβ(f/f) Prx1-Cre mice, the resting zone was dramatically elongated, the proliferation zone and hypertrophic zone of the growth plates were drastically shortened and disorganized, and trabecular bone formation was reduced. Moreover, in 1-month-old Cbfβ(f/f) Prx1-Cre mice, the growth plates were severely deformed and trabecular bone was almost absent. In addition, Cbfβ deficiency impaired intramembranous bone formation both in vivo and in vitro. Interestingly, although the expression of Indian hedgehog (Ihh) was largely reduced, the expression of parathyroid hormone-related protein (PTHrP) receptor (PPR) was dramatically increased in the Cbfβ(f/f) Prx1-Cre growth plate, indicating that that Cbfβ deficiency disrupted the Ihh-PTHrP negative regulatory loop. Chromatin immunoprecipitation (ChIP) analysis and promoter luciferase assay demonstrated that the Runx/Cbfβ complex binds putative Runx-binding sites of the Ihh promoter regions, and also the Runx/Cbfβ complex directly upregulates Ihh expression at the transcriptional level. Consistently, the expressions of Ihh target genes, including CyclinD1, Ptc, and Pthlh, were downregulated in Cbfβ-deficient chondrocytes. Taken together, our study reveals not only that Cbfβ is essential for chondrocyte proliferation and differentiation for the growth and maintenance of the skeleton in postnatal mice, but also that it functions in upregulating Ihh expression to promoter chondrocyte proliferation and osteoblast differentiation, and inhibiting PPR expression to enhance chondrocyte differentiation.
authors.affiliation: Shanghai Institute of Traumatology and Orthopedics, Ruijin Hospital, Jiao Tong University School of Medicine, Shanghai 200025, People's Republic of China.|Department of Pathology, University of Alabama at Birmingham, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Tian
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, USA.|Institute of Genetics, Life Science College, Zhejiang University, People's Republic of China.
authors.forename: Mengrui
authors.initials: M
authors.lastname: Wu
authors.affiliation: Shanghai Institute of Traumatology and Orthopedics, Ruijin Hospital, Jiao Tong University School of Medicine, Shanghai 200025, People's Republic of China.
authors.forename: Lianfu
authors.initials: L
authors.lastname: Deng
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, USA.
authors.forename: Guochun
authors.initials: G
authors.lastname: Zhu
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, USA.
authors.forename: Junqing
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Gao
authors.affiliation: Institute of Stomatology, Nanjing Medical University, 140 Hangzhou Road, Nanjing, Jiangsu 210029, China. USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, USA.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Li
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001842:Bone and Bones / Q000002:abnormalities / Q000378:metabolism / Q000473:pathology; D002356:Cartilage / Q000254:growth & development* / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism; D050658:Core Binding Factor beta Subunit / Q000172:deficiency / Q000378:metabolism*; D019938:Cyclin D1 / Q000378:metabolism; D004392:Dwarfism / Q000473:pathology; D005121:Extremities / Q000473:pathology; D025461:Feedback, Physiological; D018507:Gene Expression Regulation, Developmental; D006132:Growth Plate / Q000002:abnormalities / Q000473:pathology; D053823:Hedgehog Proteins / Q000235:genetics* / Q000378:metabolism; D019426:Integrases / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000378:metabolism; D051379:Mice; D010012:Osteogenesis; D010641:Phenotype; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000378:metabolism*; D055758:SOX9 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D012886:Skull / Q000378:metabolism / Q000473:pathology; D013997:Time Factors; D015854:Up-Regulation / Q000235:genetics*
chemical_list: C493693:Cbfb protein, mouse; D050658:Core Binding Factor beta Subunit; D053823:Hedgehog Proteins; D044168:Receptor, Parathyroid Hormone, Type 1; D055758:SOX9 Transcription Factor; C514061:ihh protein, mouse; D019938:Cyclin D1; C045073:Cre recombinase; D019426:Integrases
keywords: DEVELOPMENT; GENETIC ANIMAL MODELS; GROWTH PLATE; INDIAN HEDGEHOG; OSTEOBLASTS; SIGNALING PATHWAYS