IRF6 and SPRY4 Signaling Interact in Periderm Development.

Area of Science:

• Genetics and Developmental Biology
• Molecular and Cellular Biology

Background:

• Rare mutations in IRF6 and GRHL3 are linked to Van der Woude syndrome, an orofacial clefting disorder.
• Common variants in IRF6, GRHL3, and receptor tyrosine kinase (RTK) pathway genes contribute to isolated orofacial clefting.
• Mouse models show Irf6 loss or altered Fgf signaling cause abnormal oral epithelial adhesions and cleft palate, potentially due to disrupted periderm formation.

Purpose of the Study:

• To investigate the interaction between IRF6 and SPRY4 signaling in periderm function.
• To determine the combined effect of Irf6 heterozygous deficiency and Spry4 overexpression on oral epithelial adhesions.
• To explore the molecular mechanisms underlying these interactions in the context of orofacial clefting.

Main Methods:

• Crossed Irf6 heterozygous mice with transgenic mice overexpressing Spry4 in the basal epithelium (TgKRT14::Spry4).
• Utilized a novel quantitative assay to assess abnormal oral epithelial adhesions in double mutant embryos (Irf6+/-;TgKRT14::Spry4).
• Analyzed periderm-like cell markers (keratin 6) and gene expression (GRHL3) at sites of abnormal oral adhesions.

Main Results:

• While individual mutations caused oral adhesions, double mutants exhibited a nonadditive effect in the most severely affected embryos.
• Periderm-like cells expressing keratin 6 were present at abnormal adhesion sites.
• Abnormal expression of GRHL3 was observed in the double mutant embryos.

Conclusions:

• IRF6 and SPRY4 signaling pathways interact in regulating periderm differentiation and function.
• These findings suggest a potential interaction between IRF6 and RTK signaling in human orofacial clefting.
• The study provides a rationale for screening epistatic interactions between IRF6 and RTK pathway gene variants in human populations.