title: Crosstalk between nuclear factor I-C and transforming growth factor-β1 signaling regulates odontoblast differentiation and homeostasis.
abstract: Transforming growth factor-β1 (TGF-β1) signaling plays a key role in vertebrate development, homeostasis, and disease. Nuclear factor I-C (NFI-C) has been implicated in TGF-β1 signaling, extracellular matrix gene transcription, and tooth root development. However, the functional relationship between NFI-C and TGF-β1 signaling remains uncharacterized. The purpose of this study was to identify the molecular interactions between NFI-C and TGF-β1 signaling in mouse odontoblasts. Real-time polymerase chain reaction and western analysis demonstrated that NFI-C expression levels were inversely proportional to levels of TGF-β1 signaling molecules during in vitro odontoblast differentiation. Western blot and immunofluorescence results showed that NFI-C was significantly degraded after TGF-β1 addition in odontoblasts, and the formation of the Smad3 complex was essential for NFI-C degradation. Additionally, ubiquitination assay results showed that Smurf1 and Smurf2 induced NFI-C degradation and polyubiquitination in a TGF-β1-dependent manner. Both kinase and in vitro binding assays revealed that the interaction between NFI-C and Smurf1/Smurf2 requires the activation of the mitogen-activated protein kinase pathway by TGF-β1. Moreover, degradation of NFI-C induced by TGF-β1 occurred generally in cell types other than odontoblasts in normal human breast epithelial cells. In contrast, NFI-C induced dephosphorylation of p-Smad2/3. These results show that crosstalk between NFI-C and TGF-β1 signaling regulates cell differentiation and homeostatic processes in odontoblasts, which might constitute a common cellular mechanism.
authors.affiliation: Department of Oral Histology-Developmental Biology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea.
authors.forename: Dong-Seol
authors.initials: DS
authors.lastname: Lee
authors.forename: Won-Joon
authors.initials: WJ
authors.lastname: Yoon
authors.forename: Eui Sic
authors.initials: ES
authors.lastname: Cho
authors.forename: Heung-Joong
authors.initials: HJ
authors.lastname: Kim
authors.forename: Richard M
authors.initials: RM
authors.lastname: Gronostajski
authors.forename: Moon-Il
authors.initials: MI
authors.lastname: Cho
authors.forename: Joo-Cheol
authors.initials: JC
authors.lastname: Park
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D057809:HEK293 Cells; D006706:Homeostasis / Q000187:drug effects / Q000235:genetics; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008954:Models, Biological; D051839:NFI Transcription Factors / Q000378:metabolism*; D009804:Odontoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism* / Q000494:pharmacology; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D051839:NFI Transcription Factors; D051899:Smad2 Protein; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; C492381:Smurf1 protein, mouse; C533325:Smurf2 protein, mouse; D044767:Ubiquitin-Protein Ligases