Kousa Y A, Roushangar R, Patel N, Walter A, Marangoni P, Krumlauf R, Klein O D, Schutte B C
1 Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA.
2 Pediatrics and Human Development, Michigan State University, East Lansing, MI, USA.
J Dent Res. 2017 Oct;96(11):1306-1313. doi: 10.1177/0022034517719870. Epub 2017 Jul 21.
Rare mutations in IRF6 and GRHL3 cause Van der Woude syndrome, an autosomal dominant orofacial clefting disorder. Common variants in IRF6 and GRHL3 also contribute risk for isolated orofacial clefting. Similarly, variants within genes that encode receptor tyrosine kinase (RTK) signaling components, including members of the FGF pathway, EPHA3 and SPRY2, also contribute risk for isolated orofacial clefting. In the mouse, loss of Irf6 or perturbation of Fgf signaling leads to abnormal oral epithelial adhesions and cleft palate. Oral adhesions can result from a disruption of periderm formation. Here, we find that IRF6 and SPRY4 signaling interact in periderm function. We crossed Irf6 heterozygous ( Irf6) mice with transgenic mice that express Spry4 in the basal epithelial layer ( Tg). While embryos with either of these mutations can have abnormal oral adhesions, using a new quantitative assay, we observed a nonadditive effect of abnormal oral epithelial adhesions in the most severely affected double mutant embryos ( Irf6;Tg). At the molecular level, the sites of abnormal oral adhesions maintained periderm-like cells that express keratin 6, but we observed abnormal expression of GRHL3. Together, these data suggest that Irf6 and RTK signaling interact in regulating periderm differentiation and function, as well as provide a rationale to screen for epistatic interactions between variants in IRF6 and RTK signaling pathway genes in human orofacial clefting populations.
IRF6和GRHL3中的罕见突变会导致范德伍迪综合征，这是一种常染色体显性遗传性口面部裂畸形疾病。IRF6和GRHL3中的常见变异也会增加孤立性口面部裂畸形的风险。同样，编码受体酪氨酸激酶（RTK）信号传导成分的基因内的变异，包括FGF途径的成员、EPHA3和SPRY2，也会增加孤立性口面部裂畸形的风险。在小鼠中，Irf6缺失或Fgf信号传导紊乱会导致口腔上皮粘连异常和腭裂。口腔粘连可能是由于周皮形成中断所致。在这里，我们发现IRF6和SPRY4信号在周皮功能中相互作用。我们将Irf6杂合（Irf6）小鼠与在基底上皮层表达Spry4的转基因小鼠（Tg）进行杂交。虽然这两种突变的胚胎都可能出现口腔粘连异常，但使用一种新的定量分析方法，我们在受影响最严重的双突变胚胎（Irf6；Tg）中观察到口腔上皮粘连异常的非加性效应。在分子水平上，口腔粘连异常的部位保留了表达角蛋白6的周皮样细胞，但我们观察到GRHL3表达异常。总之，这些数据表明Irf6和RTK信号在调节周皮分化和功能方面相互作用，也为在人类口面部裂畸形人群中筛选IRF6和RTK信号通路基因变异之间的上位性相互作用提供了理论依据。
