title: The spatiotemporal expression of TGF-beta1 and its receptors during periosteal chondrogenesis in vitro.
abstract: Transforming growth factor-beta1 (TGF-beta1) has been shown to stimulate chondrogenesis in periosteal explants cultured in agarose suspension. TGF-betas exert their cellular effects through a heteromeric cell membrane receptor complex consisting of TGF-beta type I and type II receptors. In this study, the spatial and temporal expressions of the type I receptor (TbetaR-I), type II receptor (TbetaR-II) and endogenous TGF-beta1 in periosteal explants cultured in vitro were examined using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The temporal changes in the expression of the TbetaR-I and TbetaR-II mRNAs correlated with that of TGF-beta1. Exogenous administration of TGF-beta1 upregulated the expression of both receptors and of the TGF-beta1 ligand in a biphasic pattern. The earlier peak of upregulation was observed at 7 days in culture. A later peak of upregulation was seen at 42 days, at which time cartilage formation reached a maximum. Immunohistochemical studies demonstrated co-localization of TbetaR-I and TbetaR-II simultaneously among the same cells expressing TGF-beta1. TGF-beta1 treatment increased the expression of TGF-beta1, TbetaR-I and TbetaR-II in mesenchymal cells in the cambium layer at 7 days in culture. Small round chondrocytes showed widely distributed immunoreactivity of TGF-beta1, TbetaR-I and TbetaR-II in the 42-day explants treated with TGF-beta1. These observations support the hypothesis that TGF-beta1 regulates the initiation and formation of cartilage during periosteal chondrogenesis.
authors.affiliation: Department of Orthopedics, Mayo Clinic, Mayo Foundation, Rochester, MN 55905, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizuta
authors.forename: Arunik
authors.initials: A
authors.lastname: Sanyal
authors.forename: Takumi
authors.initials: T
authors.lastname: Fukumoto
authors.forename: James S
authors.initials: JS
authors.lastname: Fitzsimmons
authors.forename: Nobuzo
authors.initials: N
authors.lastname: Matsui
authors.forename: Mark E
authors.initials: ME
authors.lastname: Bolander
authors.forename: Merry Jo
authors.initials: MJ
authors.lastname: Oursler
authors.forename: Shawn W
authors.initials: SW
authors.lastname: O'Driscoll
mesh_terms: D030201:Activin Receptors, Type I / Q000235:genetics; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D020219:Chondrogenesis / Q000502:physiology*; D018076:DNA, Complementary / Q000235:genetics; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D010521:Periosteum / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D014018:Tissue Distribution; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II