Tbx1 regulates oral epithelial adhesion and palatal development

Area of Science:

• Developmental Biology
• Genetics
• Craniofacial Development

Background:

• Cleft palate is a common craniofacial birth defect with complex etiology.
• The precise causes of various cleft palate forms, including submucosal clefts, remain unclear.
• T-box transcriptional factors (Tbx) play critical roles in embryonic development.

Purpose of the Study:

• To investigate the role of Tbx1 in palatal fusion and oral mucosal differentiation.
• To elucidate the pathogenesis of cleft palate phenotypes associated with Tbx1 disruption.
• To understand the contribution of Tbx1 to 22q11.2 deletion syndrome.

Main Methods:

• Generation and analysis of Tbx1-null (Tbx1(-/-)) and keratinocyte-specific Tbx1-conditional knockout (Tbx1(KCKO)) mice.
• Histological examination of palatal development and epithelial adhesion.
• In vitro studies using MCF7 epithelial cells to assess Tbx1's effect on cell growth and cell-cycle arrest.

Main Results:

• Tbx1 disruption in mice led to abnormal epithelial adhesion and various forms of cleft palate.
• Tbx1-null mice exhibited hyperproliferative epithelium that failed to differentiate properly.
• Tbx1 inactivation in keratinocytes caused anterior incomplete cleft palate; Tbx1 overexpression induced cell-cycle arrest in epithelial cells.

Conclusions:

• Tbx1 is essential for regulating the balance between keratinocyte proliferation and differentiation during palatogenesis.
• Impaired epithelial adhesion and compromised mesenchymal growth due to Tbx1 deficiency underlie cleft palate phenotypes.
• This study reveals novel insights into the pathogenesis of incomplete and submucous cleft palate.