Department of Anatomy and Cell Biology and the Craniofacial Anomalies Research Center, The University of Iowa, Iowa City, IA, 52242, USA.
Department of Endodontics, College of Dentistry, The University of Iowa, Iowa City, IA, 52242, USA; Iowa Institute of Oral Health Research, University of Iowa, Iowa City, IA, 52242, USA.
Dev Biol. 2020 Feb 15;458(2):246-256. doi: 10.1016/j.ydbio.2019.11.010. Epub 2019 Nov 23.
In this study, we investigated the role of the transcription factor Six2 in palate development. Six2 was selected using the SysFACE tool to predict genes from the 2p21 locus, a region associated with clefting in humans by GWAS, that are likely to be involved in palatogenesis. We functionally validated the predicted role of Six2 in palatogenesis by showing that 22% of Six2 null embryos develop cleft palate. Six2 contributes to palatogenesis by promoting mesenchymal cell proliferation and regulating bone formation. The clefting phenotype in Six2 embryos is similar to Pax9 null embryos, so we examined the functional relationship of these two genes. Mechanistically, SIX2 binds to a PAX9 5' upstream regulatory element and activates PAX9 expression. In addition, we identified a human SIX2 coding variant (p.Gly264Glu) in a proband with cleft palate. We show this missense mutation affects the stability of the SIX2 protein and leads to decreased PAX9 expression. The low penetrance of clefting in the Six2 null mouse combined with the mutation in one patient with cleft palate underscores the potential combinatorial interactions of other genes in clefting. Our study demonstrates that Six2 interacts with the developmental gene regulatory network in the developing palate.
在这项研究中，我们研究了转录因子 Six2 在腭发育中的作用。Six2 是使用 SysFACE 工具选择的，该工具用于预测与 GWAS 中人类裂隙相关的 2p21 基因座上的基因，这些基因可能参与腭发生。我们通过证明 22%的 Six2 缺失胚胎发生腭裂，功能验证了 Six2 在腭发生中的预测作用。Six2 通过促进间充质细胞增殖和调节骨形成来促进腭发生。Six2 胚胎的裂隙表型与 Pax9 缺失胚胎相似，因此我们研究了这两个基因的功能关系。从机制上讲，SIX2 与 PAX9 的 5'上游调控元件结合并激活 PAX9 的表达。此外，我们在一个腭裂患者中鉴定出一个人类 SIX2 编码变异（p.Gly264Glu）。我们表明，这种错义突变影响 SIX2 蛋白的稳定性，并导致 PAX9 表达减少。Six2 缺失小鼠中腭裂的低外显率加上一个腭裂患者的突变，突出了其他基因在腭裂中的潜在组合相互作用。我们的研究表明，Six2 与发育中的腭的发育基因调控网络相互作用。
