Institute of Developmental and Regenerative Biology, College of Life and Environmental Science, Hangzhou Normal University, Zhejiang, China Key Laboratory of Mammalian Organogenesis and Regeneration, Zhejiang, China Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences and BK21 Program, Chonbuk National University School of Dentistry, Jeonju, South Korea.
Institute of Developmental and Regenerative Biology, College of Life and Environmental Science, Hangzhou Normal University, Zhejiang, China Key Laboratory of Mammalian Organogenesis and Regeneration, Zhejiang, China.
J Dent Res. 2015 Jul;94(7):961-7. doi: 10.1177/0022034515583532. Epub 2015 Apr 28.
Cleft palate represents one of the major congenital birth defects in humans. Despite the essential roles of ectodermal canonical Wnt and mesenchymal Wnt signaling in the secondary palate development, the function of mesenchymal canonical Wnt activity in secondary palate development remains elusive. Here we show that Gpr177, a highly conserved transmembrane protein essential for Wnt trafficking, is required for secondary palate development. Gpr177 is expressed in both epithelium and mesenchyme of palatal shelves during mouse development. Wnt1(Cre)-mediated deletion of Gpr177 in craniofacial neural crest cells leads to a complete cleft secondary palate, which is formed mainly due to aberrant cell proliferation and increased cell death in palatal shelves. By BATGAL staining, we reveal an intense canonical Wnt activity in the anterior palate mesenchyme of E12.5 wild-type embryos but not in Gpr177(Wnt1-Cre) embryos, suggesting that mesenchymal canonical Wnt signaling activated by Gpr177-mediated mesenchymal Wnts is critical for secondary palate development. Moreover, phosphorylation of JNK and c-Jun is impaired in the Gpr177(Wnt1-Cre) palate and is restored by implantation of Wnt5a-soaked beads in the in vitro palate explants, suggesting that Gpr177 probably regulates palate development via the Wnt5a-mediated noncanonical Wnt pathway in which c-Jun and JNK are involved. Importantly, certain cellular processes and the altered gene expression in palates lacking Gpr177 are distinct from that of the Wnt5a mutant, further demonstrating involvement of other mesenchymal Wnts in the process of palate development. Together, these results suggest that mesenchymal Gpr177 is required for secondary palate development by regulating and integrating mesenchymal canonical and noncanonical Wnt signals.
腭裂是人类主要的先天性出生缺陷之一。尽管外胚层经典 Wnt 和间质 Wnt 信号在腭的二次发育中起着至关重要的作用，但间质经典 Wnt 活性在腭的二次发育中的作用仍不清楚。在这里，我们发现 Gpr177 是一种高度保守的跨膜蛋白，对 Wnt 运输至关重要，它是腭发育所必需的。Gpr177 在小鼠发育过程中腭板的上皮和间质中均有表达。颅面神经嵴细胞中 Wnt1(Cre)介导的 Gpr177 缺失导致完全腭裂，这主要是由于腭板中异常的细胞增殖和增加的细胞死亡所致。通过 BATGAL 染色，我们在 E12.5 野生型胚胎的前腭间质中发现了强烈的经典 Wnt 活性，但在 Gpr177(Wnt1-Cre)胚胎中没有，这表明 Gpr177 介导的间质 Wnts 激活的间质经典 Wnt 信号对腭的二次发育至关重要。此外，Gpr177(Wnt1-Cre)腭中的 JNK 和 c-Jun 的磷酸化受损，并且通过在体外腭外植体中植入 Wnt5a 浸泡的珠粒可恢复，这表明 Gpr177 可能通过涉及 c-Jun 和 JNK 的 Wnt5a 介导的非经典 Wnt 途径来调节腭的发育。重要的是，缺乏 Gpr177 的腭中的某些细胞过程和改变的基因表达与 Wnt5a 突变体不同，这进一步证明了其他间质 Wnt 参与了腭发育的过程。总之，这些结果表明，间质 Gpr177 通过调节和整合间质经典和非经典 Wnt 信号来调节间质经典和非经典 Wnt 信号，从而调节间质经典和非经典 Wnt 信号，从而调节间质经典和非经典 Wnt 信号。
