Gene expression analysis reveals that formation of the mouse anterior secondary palate involves recruitment of cells from the posterior side.
Cleft palate is a common birth defect caused by disruptions in secondary palate development. Anterior-posterior (A-P) regional specification plays a critical role in palate development and fusion. Previous studies have shown that at the molecular level, the anterior palate can be defined by the expression of Shox-2 and the posterior palate by Meox-2 expression in certain mouse strains. Here, we have extended previous studies by performing a more detailed analysis of these genes during mouse palate development. We found that the expression patterns of Shox-2 and Meox-2 are dynamic during palate development. At embryonic day 12.5 (E12.5), Shox-2 expression is localized to the anterior end and its expression domain covers less than 25% of the length of the palate shelf. The Shox-2 expression domain then gradually expands towards the posterior end and ultimately occupies more than 60% of the palate shelf by E14.5. The expansion of the Shox-2 domain may involve induction of Shox2 expression in additional cells. Reciprocally, the Meox-2 expression domain at E12.5 covers a large portion of the palate shelf, a region more than 70% of the entire palate, but then regresses to the posterior 25% by E14.5. This regression is likely caused by the repression of Meox-2 expression in certain Meox2 expressing cells, rather than the cessation of cell proliferation. Therefore, certain Meox-2 positive "primitive posterior cells" are differentiated/converted into Shox-2 positive "definitive anterior cells" during A-P regional specification.
Li
Qun
Q
Department of Molecular, Cellular and Craniofacial Biology and Birth Defects Center, University of Louisville, KY 40202, USA.
Ding
Jixiang
J
D000818:Animals; D002455:Cell Division; D002972:Cleft Palate / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D051957:MSX1 Transcription Factor / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D010160:Palate, Soft / Q000166:cytology / Q000196:embryology* / Q000502:physiology
D018398:Homeodomain Proteins; D051957:MSX1 Transcription Factor; C484194:Meox2 protein, mouse; C484084:Msx1 protein, mouse; C484663:Shox2 protein, mouse