Elucidating the role of Polycomb Repressive Complexes in Lingual Papillae Development

总结 舌头是一个复杂的器官，对咀嚼、味觉和交流至关重要。 舌头的正常发育取决于不同组织之间复杂的相互作用，包括 肌肉、结缔组织和上皮。重要的是，如果不能建立这些相互作用， 发育缺陷，如无舌症、小舌症和舌系带过短。舌上皮是一组 上皮间充质附属物称为乳头。菌状乳头是味蕾的港湾 感觉。它们被角化的、非味觉的丝状乳头包围， 功能协调发展的Wnt和Shh信号通路是调节神经细胞的形成和发育的核心参与者。 菌状和丝状乳头;然而，细胞内在机制在特化和 这些建筑的维护情况仍不清楚。多梳阻遏复合物（PRC）1是一种主要的染色质 转录调节因子，并已被证明在谱系身份和早期胚胎发育中发挥关键作用。 然而，PRC 1介导的细胞谱系调节尚未在口腔组织中探索。 为了研究PRC 1在舌乳头发育中的作用，我们产生了小鼠，其中 PRC 1的基本亚基Ring 1a和Ring 1b在基底舌上皮细胞中被条件性地去除 （环1a/B 2KO）。我们的研究结果表明，在Ring 1a/B 2 KO小鼠中，菌状乳头没有维持， 丝状乳头不形成。对Ring 1a/b缺失舌上皮的进一步分析显示 Sonic Hedgehog（Shh）配体和转录因子Sox 2的广泛表达，而在 在对照小鼠中，这些基因的表达仅限于味觉祖细胞。的表达模式 Wnt信号通路的组分Wnt 10 B和Lef 1在Ring 1a/B 2 KO中也发生了改变;然而， 并不导致异常的经典Wnt信号传导。我们假设PRC 1限制基因表达， 从而促进舌乳头图案化和形成。剖析PRC 1的分子机制 为了控制舌上皮，我们将对FACS纯化的对照和Ring 1a/B进行RNA-seq分析。 无效舌上皮细胞。该分析将与具有针对PRC 1亚基的抗体的ChIP-seq结合 以确定PRC 1的直接目标确定Ring 1a/b-null中被破坏的特定分子途径 舌上皮，我们将进行基因本体论分析，并集中在候选基因，调节 上皮-间充质相互作用、转录调节和谱系身份。我们将分析 通过进行体内遗传学实验来确定候选基因的功能意义。 总之，我们的研究将使我们能够阐明PRC 1对舌上皮细胞的调节，包括其在舌上皮细胞中的表达。 与发育信号通路的相互作用。理解复杂的分子间相互作用 舌组织也可以帮助我们揭示先天性舌畸形形成的机制。

Summary The tongue is a complex organ that is essential for mastication, taste sensation, and communication. Proper development of the tongue is dependent on complex interactions between different tissues, including muscle, connective tissue, and epithelium. Importantly, failure to establish these interactions leads to developmental defects, such as aglossia, microglossia, and ankyloglossia. The lingual epithelium is an array of epithelial-mesenchymal appendages termed papillae. Fungiform papillae harbor taste buds required for taste sensation. They are surrounded by keratinized, non-gustatory filiform papillae, which provide essential barrier functions. Wnt and Shh signaling pathways are central players in regulating the patterning and development of fungiform and filiform papillae; however, the role of cell-intrinsic mechanisms in the specification and maintenance of these structures remains unclear. Polycomb repressive complex (PRC) 1 is a major chromatin transcriptional regulator and has been shown to play a critical role in lineage identity and early embryonic development; however, PRC1-mediated regulation of cell lineages has yet to be explored in oral tissues. To investigate the role of PRC1 in the development of lingual papillae, we generated mice in which essential PRC1 subunits, Ring1a and Ring1b, were conditionally ablated in the basal lingual epithelial cells (Ring1a/b 2KO). Our results showed that in Ring1a/b 2KO mice, the fungiform papillae are not maintained and the filiform papillae are not formed. Further analysis of the Ring1a/b-null lingual epithelium revealed widespread expression of the Sonic Hedgehog (Shh) ligand and the transcription factor Sox2, whereas in control mice, the expression of these genes was confined to taste progenitors. The expression pattern of components of the Wnt signaling pathway, Wnt10b and Lef1, was also altered in Ring1a/b 2KO; however, this did not result in aberrant canonical Wnt signaling. We hypothesize that PRC1 restricts gene expression and thus promotes lingual papilla patterning and formation. To dissect the molecular mechanisms of PRC1's control of the lingual epithelium, we will carry out an RNA-seq analysis of FACS-purified control and Ring1a/b- null lingual epithelial cells. This analysis will be coupled with ChIP-seq with antibodies against PRC1 subunits to identify the direct targets of PRC1. To identify the specific molecular pathways disrupted in the Ring1a/b-null lingual epithelium, we will carry out Gene Ontology analysis and focus on candidate genes that regulate epithelial-mesenchymal interactions, transcriptional regulation, and lineage identity. We will analyze the functional significance of the candidate genes by performing genetic experiments in vivo. Together, our studies will allow us to elucidate PRC1's regulation of the lingual epithelium, including its interaction with developmental signaling pathways. Understanding the complex molecular interactions between lingual tissues may also help us to reveal the mechanisms that cause congenital tongue abnormalities to form.