School of Dentistry, School of Medicine, University of Utah, Salt Lake City, Utah, USA.
Department of Neurobiology & Anatomy, School of Medicine, University of Utah, Salt Lake City, Utah, USA.
Dev Dyn. 2020 Oct;249(10):1274-1284. doi: 10.1002/dvdy.189. Epub 2020 Aug 4.
BACKGROUND: Despite the strides made in understanding the complex network of key regulatory genes and cellular processes that drive palate morphogenesis, patients suffering from these conditions face treatment options that are limited to complex surgeries and multidisciplinary care throughout life. Hence, a better understanding of how molecular interactions drive palatal growth and fusion is critical for the development of treatment and preventive strategies for cleft palates in humans. Our previous work demonstrated that Pax9-dependent Wnt signaling is critical for the growth and fusion of palatal shelves. We showed that controlled intravenous delivery of small molecule Wnt agonists specifically blocks the action of Dkks (inhibitors of Wnt signaling) and corrects secondary palatal clefts in Pax9 mice. While these data underscore the importance of the functional upstream relationship of Pax9 to the Wnt pathway, not much is known about how the genetic nature of Pax9's interactions in vivo and how it modulates the actions of these downstream effectors during palate formation. RESULTS: Here, we show that the genetic reduction of Dkk1 during palatogenesis corrected secondary palatal clefts in Pax9 mice with restoration of Wnt signaling activities. In contrast, genetically induced overexpression of Dkk1 mice phenocopied the defects in tooth and palate development visible in Pax9 strains. Results of ChIP-qPCR assays showed that Pax9 can bind to regions near the transcription start sites of Dkk1 and Dkk2 as well as the intergenic region of Wnt9b and Wnt3 ligands that are downregulated in Pax9 palates. CONCLUSIONS: Taken together, these data suggest that the molecular mechanisms underlying Pax9's role in modulating Wnt signaling activity likely involve the inhibition of Dkk expression and the control of Wnt ligands during palatogenesis.
背景:尽管在理解驱动腭裂发生的关键调控基因和细胞过程的复杂网络方面已经取得了进展,但患有这些疾病的患者的治疗选择仅限于复杂的手术和终生多学科护理。因此,更好地了解分子相互作用如何驱动腭的生长和融合对于开发人类腭裂的治疗和预防策略至关重要。我们之前的工作表明,Pax9 依赖性 Wnt 信号对于腭架的生长和融合至关重要。我们表明,小分子 Wnt 激动剂的静脉内控制递送特异性阻断 Dkks(Wnt 信号抑制剂)的作用,并纠正 Pax9 小鼠中的继发腭裂。虽然这些数据强调了 Pax9 对 Wnt 途径的功能上游关系的重要性,但对于 Pax9 在体内的遗传性质及其如何在腭形成过程中调节这些下游效应子的作用知之甚少。
结果:在这里,我们表明在腭发生过程中降低 Dkk1 的遗传水平可纠正 Pax9 小鼠中的继发腭裂,并恢复 Wnt 信号活性。相比之下,基因诱导的 Dkk1 过表达小鼠在牙齿和腭发育方面表现出与 Pax9 品系中可见的缺陷相似的表型。ChIP-qPCR 测定的结果表明,Pax9 可以结合 Dkk1 和 Dkk2 的转录起始位点附近区域以及 Wnt9b 和 Wnt3 配体的基因间区域,这些区域在 Pax9 腭中下调。
结论:综上所述,这些数据表明 Pax9 调节 Wnt 信号活性的分子机制可能涉及抑制 Dkk 表达和控制腭发生过程中的 Wnt 配体。
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