title: The forkhead transcription factor Foxc2 promotes osteoblastogenesis via up-regulation of integrin β1 expression.
abstract: The forkhead box C2 (Foxc2) protein, a member of the forkhead/winged helix transcription factor family, plays an important role in regulation of metabolism, arterial specification, and vascular sprouting. Foxc2-null mutants die prenatally or perinatally, and they exhibit hypoplasia of the vertebrae and insufficient chondrification or ossification of medial structures. However, the role of Foxc2 in osteoblastogenesis is not yet fully understood. According to the degree of differentiation of osteoblasts, we found that Foxc2 expression was gradually increased and dose-dependently up-regulated by well-known bone anabolic agents, such as hPTH(1-34) and BMP2. In ex vivo mouse calvarial organ culture, a significant reduction of the basal expression of Foxc2 induced by siFoxc2 remarkably suppressed cell proliferation and differentiation and induced cell death. Knockdown of Foxc2 expression using siFoxc2 in both MC3T3-E1 and primary mouse calvarial cells also resulted in a significant suppression of proliferation and differentiation, and induced cell death, supporting the ex vivo observations. In addition, the resistance to apoptosis induced by serum deprivation and phosphorylation of both Akt and ERK was significantly reduced after siFoxc2 treatment. Conversely, overexpression of Foxc2 increased the proliferation of MC3T3-E1 and primary mouse calvarial cells. Furthermore, we found that Foxc2 enhanced the expression of integrin β1, an important modulator of osteoblastogenesis, by direct binding to a Forkhead-binding element in its promoter. Taken together, these results indicate that Foxc2 plays an important role in osteoblastogenesis by promoting osteoblast proliferation, survival and differentiation through up-regulation of integrin β1 in response to stimuli which induce bone formation.
authors.affiliation: Brain Korea 21 Project for Medical Science, College of Medicine, Yonsei University, Seoul, Republic of Korea. sujin153@naver.com
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Park
authors.forename: Jogeswar
authors.initials: J
authors.lastname: Gadi
authors.forename: Kyoung-Won
authors.initials: KW
authors.lastname: Cho
authors.forename: Kwang Joon
authors.initials: KJ
authors.lastname: Kim
authors.forename: Se Hwa
authors.initials: SH
authors.lastname: Kim
authors.forename: Han-Sung
authors.initials: HS
authors.lastname: Jung
authors.forename: Sung-Kil
authors.initials: SK
authors.lastname: Lim
mesh_terms: D016475:3T3 Cells; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology; D002453:Cell Cycle / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation; D002470:Cell Survival; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D039482:Integrin alpha5 / Q000235:genetics / Q000378:metabolism; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010281:Parathyroid Hormone / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012886:Skull / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D046509:Tissue Culture Techniques; D015854:Up-Regulation
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D051858:Forkhead Transcription Factors; D039482:Integrin alpha5; D019012:Integrin beta1; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D034741:RNA, Small Interfering; C082078:mesenchyme fork head 1 protein; C102836:parathyroid hormone (1-31)amide, human