Association between palatal morphogenesis and Pax9 expression pattern in CL/Fr embryos with clefting during palatal...

Area of Science:

• Developmental Biology
• Genetics
• Craniofacial Development

Background:

• Cleft lip and palate (CLP) is a common congenital condition.
• The CL/Fr mouse strain exhibits spontaneous CLP.
• Pax9 gene expression is critical for craniofacial development.

Purpose of the Study:

• To investigate Pax9 mRNA expression during palatal morphogenesis in CL/Fr embryos.
• To assess the correlation between secondary palatal morphogenesis and Pax9 expression in spontaneous CLP.

Main Methods:

• Whole mount in situ hybridization using a digoxigenin-labeled probe.
• Analysis of Pax9 mRNA expression in palatal shelves of normal (C57BL/6, CL/Fr-N) and cleft (CL/Fr-BCL) embryos.
• Organ culture of palatal shelves from E13.5 embryos to assess expression in separated versus paired shelves.

Main Results:

• Pax9 mRNA was expressed in the medial edge (ME) of palatal shelves in normal embryos during key stages of palatal elevation (E13.5-E14.5) and downregulated upon fusion (E15.5).
• In CL/Fr cleft embryos, Pax9 remained expressed in the ME region on E15.5, failing to downregulate.
• Organ culture showed sustained Pax9 expression in separated CL/Fr-N and CL/Fr-BCL palatal shelves, but downregulation in paired shelves.

Conclusions:

• Altered Pax9 mRNA expression patterns are associated with spontaneous cleft lip and palate in CL/Fr mice.
• There is a direct correlation between abnormal Pax9 expression and impaired palatal fusion.
• Pax9 plays a significant role in the regulation of palatal fusion.