title: TBX1 protein interactions and microRNA-96-5p regulation controls cell proliferation during craniofacial and dental development: implications for 22q11.2 deletion syndrome.
abstract: T-box transcription factor TBX1 is the major candidate gene for 22q11.2 deletion syndrome (22q11.2DS, DiGeorge syndrome/Velo-cardio-facial syndrome), whose phenotypes include craniofacial malformations such as dental defects and cleft palate. In this study, Tbx1 was conditionally deleted or over-expressed in the oral and dental epithelium to establish its role in odontogenesis and craniofacial developmental. Tbx1 lineage tracing experiments demonstrated a specific region of Tbx1-positive cells in the labial cervical loop (LaCL, stem cell niche). We found that Tbx1 conditional knockout (Tbx1(cKO)) mice featured microdontia, which coincides with decreased stem cell proliferation in the LaCL of Tbx1(cKO) mice. In contrast, Tbx1 over-expression increased dental epithelial progenitor cells in the LaCL. Furthermore, microRNA-96 (miR-96) repressed Tbx1 expression and Tbx1 repressed miR-96 expression, suggesting that miR-96 and Tbx1 work in a regulatory loop to maintain the correct levels of Tbx1. Cleft palate was observed in both conditional knockout and over-expression mice, consistent with the craniofacial/tooth defects associated with TBX1 deletion and the gene duplication that leads to 22q11.2DS. The biochemical analyses of TBX1 human mutations demonstrate functional differences in their transcriptional regulation of miR-96 and co-regulation of PITX2 activity. TBX1 interacts with PITX2 to negatively regulate PITX2 transcriptional activity and the TBX1 N-terminus is required for its repressive activity. Overall, our results indicate that Tbx1 regulates the proliferation of dental progenitor cells and craniofacial development through miR-96-5p and PITX2. Together, these data suggest a new molecular mechanism controlling pathogenesis of dental anomalies in human 22q11.2DS.
authors.affiliation: Texas A&M University Health Science Center, Houston, TX, USA.
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.affiliation: Department of Anatomy and Cell Biology, Craniofacial Anomalies Research Center, The University of Iowa, Iowa City, IA, USA.
authors.forename: Myriam
authors.initials: M
authors.lastname: Moreno
authors.affiliation: Department of Anatomy and Cell Biology, Craniofacial Anomalies Research Center, The University of Iowa, Iowa City, IA, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Eliason
authors.affiliation: Texas A&M University Health Science Center, Houston, TX, USA.
authors.forename: Huojun
authors.initials: H
authors.lastname: Cao
authors.affiliation: Department of Anatomy and Cell Biology, Craniofacial Anomalies Research Center, The University of Iowa, Iowa City, IA, USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Anatomy and Cell Biology, Craniofacial Anomalies Research Center, The University of Iowa, Iowa City, IA, USA.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Yu
authors.affiliation: Department of Mineralized Tissue Biology.
authors.forename: Felicitas B
authors.initials: FB
authors.lastname: Bidlack
authors.affiliation: Center for Biomineralization, Department of Applied Oral Sciences, The Forsyth Institute, Cambridge, MA, USA and.
authors.forename: Henry C
authors.initials: HC
authors.lastname: Margolis
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University Federico II and the Institute of Genetics and Biophysics CNR, Naples, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Baldini
authors.affiliation: Department of Anatomy and Cell Biology, Craniofacial Anomalies Research Center, The University of Iowa, Iowa City, IA, USA, brad-amendt@uiowa.edu.
authors.forename: Brad A
authors.initials: BA
authors.lastname: Amendt
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D019465:Craniofacial Abnormalities; D004062:DiGeorge Syndrome / Q000196:embryology / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D005147:Facial Bones / Q000196:embryology / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism*; D014070:Tooth / Q000196:embryology / Q000378:metabolism*
chemical_list: D035683:MicroRNAs; C541554:Mirn96 microRNA, mouse; D020825:T-Box Domain Proteins; C491573:Tbx1 protein, mouse