title: Transforming growth factor-beta1 (TGF-beta1) regulates ATDC5 chondrogenic differentiation and fibronectin isoform expression.
abstract: Regulated splicing of fibronectin (FN) occurs during the mesenchymal to chondrocyte transition and ultimately results in the relative enrichment of an extra domain B (EDB) exon-containing FN isoform with the suggestion that FN isoforms may play a functional role in chondrogenesis. Promotion of chondrogenesis can also be achieved by treatment with transforming growth factor-beta (TGF-beta), which also regulates FN isoform expression. We have examined the effects of TGF-beta treatment on the assumption of the chondrogenic phenotype in the teratoma-derived cell line ATDC5 and tested whether these effects on chondrogenesis are paralleled by appropriate changes in FN isoform expression. ATDC5 cells were maintained in a pre-chondrogenic state and, in this state, treated with 10 ng/ml TGF-beta. The cells started to elaborate a matrix rich in sulfated proteoglycans, such that within the first 12 days of culture, TGF-beta1 treatment appeared to slightly accelerate early acquisition of an Alcian blue-stained matrix, and caused a dose- and time-dependent decrease in collagen type I expression; changes in collagen type II expression were variable. At later times, cells treated with TGF-beta became indistinguishable from those of the controls. Interestingly, TGF-beta treatment caused a significant dose- and time-dependent decrease in the proportion of FN containing the extra domain A (EDA) and the EDB exons. These data suggest that TGF-beta induces the early stages of chondrogenic maturation in this pre-chondrogenic line and that TGF-beta treatment increases expression of FN isoforms that lack the EDA and EDB exons.
authors.affiliation: Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Han
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Adams
authors.forename: Zhuliang
authors.initials: Z
authors.lastname: Tao
authors.forename: Charlene J
authors.initials: CJ
authors.lastname: Williams
authors.forename: Raihana
authors.initials: R
authors.lastname: Zaka
authors.forename: Rocky S
authors.initials: RS
authors.lastname: Tuan
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Norton
authors.forename: Noreen J
authors.initials: NJ
authors.lastname: Hickok
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D020219:Chondrogenesis / Q000187:drug effects* / Q000235:genetics; D024042:Collagen Type I / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism; D005091:Exons / Q000235:genetics; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D051379:Mice; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011509:Proteoglycans / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D013431:Sulfates / Q000737:chemistry; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
chemical_list: D024042:Collagen Type I; D024043:Collagen Type II; D005353:Fibronectins; D020033:Protein Isoforms; D011509:Proteoglycans; D012333:RNA, Messenger; D013431:Sulfates; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1