title: Collagen, type V, alpha1 (COL5A1) is regulated by TGF-beta in osteoblasts.
abstract: Bone matrix contains high concentrations of growth factors that are known to play important regulatory roles during osteogenesis, particularly transforming growth factor-beta (TGF-beta). Divergent effects of TGF-beta on bone formation have been reported both in vitro and in vivo depending upon experimental conditions, cells employed and their stage of maturation. In this study, we have used a clonal osteoblastic cell line MC3T3-E1, derived from newborn mouse calvaria, as an in vitro model of bone development. These cells undergo an ordered, time-dependent developmental sequence characterized by three stages (proliferation, differentiation and mineralization), over a 30-35-day period. In this study, cDNA microarray technology was used to study the expression profile of 8470 genes, in the presence of TGF-beta1 during osteoblast development. Microarray analysis revealed 120 cDNAs to be differentially expressed in MC3T3-E1 osteoblasts that had been treated with TGF-beta1. From the 120 differentially expressed genes, we selected Collagen, type V, alpha1 (COL5A1) {differential expression=+4.9} for further studies since it represents a previously uncharacterized component of the bone matrix. Using Northern blotting, we found that, when MC3T3-E1 cells were treated with TGF-beta1, COL5A1 was up-regulated during the proliferation and differentiation phases of osteogenesis. Furthermore, by a combination of RNA in situ hybridization and Northern blotting, we found COL5A1 mRNA to be expressed in the calvaria and developing bone of the E17.5 mouse embryos. Lastly, significant COL5A1 protein expression was observed by immunohistochemistry in the developing bone of the E17.5 mouse embryos. In conclusion, by the use of in vitro and in vivo approaches, we have discovered that the COL5A1 gene is a target of TGF-beta during osteogenesis.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Shireen
authors.initials: S
authors.lastname: Kahai
authors.forename: Calvin P H
authors.initials: CP
authors.lastname: Vary
authors.forename: Yuguang
authors.initials: Y
authors.lastname: Gao
authors.forename: Arun
authors.initials: A
authors.lastname: Seth
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D049109:Cell Proliferation; D024062:Collagen Type V / Q000096:biosynthesis* / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1; D015854:Up-Regulation
chemical_list: D024062:Collagen Type V; D018076:DNA, Complementary; D012333:RNA, Messenger; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D012313:RNA; D004247:DNA; D000469:Alkaline Phosphatase