title: FKBP12 is a negative regulator of transforming growth factor-beta receptor internalization.
abstract: Transforming growth factor-beta (TGF-beta) family polypeptides regulate cell growth and differentiation by binding to single pass serine/threonine kinases referred to as TGF-beta type I and II receptors. Although interaction screens have shown that the immunophilin FKBP12 interacts with TGF-beta type I receptors, the role of FKBP12 in TGF-beta receptor action is presently unclear. Using a chimeric TGF-beta receptor system, we have shown a specific enhancement of internalization when FKBP12 binding to the type I receptor was prevented with rapamycin. Moreover, although earlier studies demonstrated that type II receptor kinase activity was required for optimal internalization in mesenchymal cells, we found that rapamycin functioned downstream of the type II receptor kinase. Thus, rather than modulating TGF-beta signaling, our data suggest a novel role for FKBP12 as a negative regulator of TGF-beta receptor endocytosis.
authors.affiliation: Thoracic Disease Research Unit and the Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: D
authors.initials: D
authors.lastname: Yao
authors.forename: J J
authors.initials: JJ
authors.lastname: Doré
authors.forename: E B
authors.initials: EB
authors.lastname: Leof
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis; D005347:Fibroblasts / Q000378:metabolism; D005353:Fibronectins / Q000096:biosynthesis / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D020104:Immunophilins / Q000235:genetics / Q000502:physiology*; D007166:Immunosuppressive Agents / Q000494:pharmacology; D051379:Mice; D016297:Mutagenesis, Site-Directed; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D022021:Tacrolimus Binding Proteins; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D007166:Immunosuppressive Agents; D017395:Plasminogen Activator Inhibitor 1; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D022021:Tacrolimus Binding Proteins; D020104:Immunophilins; D020123:Sirolimus