Chibby and Wnt Signaling in Ciliated Cell Differentiation

描述(申请人提供)：我们的呼吸道中有大量的活动纤毛，并以波的形式同步跳动，推动吸入的碎片和粘液中的病原体进入咽部。这为预防呼吸道感染提供了一种重要的先天防御机制。在呼吸道上皮具纤毛的细胞的顶端表面，通常可发现100至300个可移动的纤毛。运动纤毛功能障碍与人类疾病，特别是原发性睫状体运动障碍(PCD)有关。尽管它们在临床上很重要，但人们对控制纤毛运动和纤毛细胞分化的关键分子和信号通路知之甚少。因此，了解这些基本的生物学现象对于开发新的治疗策略来预防和治疗PCD和其他纤毛相关疾病至关重要。CHIBBY(CBY)最初是作为Wnt/β-catenin信号通路的一种进化保守的拮抗剂被分离出来的。CBY在物理上与关键的下游辅活化子连环蛋白相互作用，并抑制连环蛋白介导的转录激活。有趣的是，CBY基因敲除(CBY-/-)小鼠由于完全缺乏粘液纤毛运输活动而遭受反复呼吸道感染，这让人想起PCD。我们的研究进一步表明，CBY-/-小鼠鼻腔和肺上皮中的纤毛细胞分化较差，其特征是活动纤毛数量显着减少。与此表型一致，我们发现内源CBY蛋白定位于纤毛的底部。因此，我们的研究结果表明，CBY在呼吸道活动纤毛的正确形成/功能中起着重要作用。然而，CBY-/-小鼠纤毛缺陷背后的细胞和分子基础在很大程度上仍未被探索。此外，CBY的纤毛功能是否与Wnt/β-catenin信号有关尚不清楚。本研究的目的是阐明CBY、CBY相互作用蛋白和Wnt/β-catenin信号在纤毛运动发生和气管纤毛细胞分化中的作用。为了实现这一目标，我们提出了以下具体目标：1.研究CBY在气管纤毛细胞分化中的作用；2.检测CBY基因在气管纤毛细胞分化过程中的转录调控；3.分离CBY结合伙伴并确定它们在纤毛细胞分化中的作用。我们期望这些实验将有助于从根本上理解纤毛发生和纤毛细胞分化的分子和细胞机制。 与公共健康相关：可移动的纤毛(纤毛细胞的微小毛状突起)排列在我们的呼吸道来回波动，有效地清除吸入的碎片和粘液中的微生物，而功能障碍的纤毛患者反复受到呼吸道感染，导致呼吸功能不全。因此，了解运动纤毛形成和纤毛细胞分化的机制对于开发治疗由纤毛功能障碍引起的疾病的新疗法至关重要。我们的研究探讨了CHIBBY蛋白和Wnt信号通路在运动纤毛形成和纤毛细胞分化中的作用，很可能有助于我们更好地理解这些重要的生物学过程。

DESCRIPTION (provided by applicant): Motile cilia are abundant in our respiratory tract, and beat synchronously in waves to propel inhaled debris and pathogens entrapped in mucus to the pharynx. This provides an important innate defense mechanism against respiratory infections. Motile cilia are usually found as clusters of 100 to 300 on the apical surface of a ciliated cell in the respiratory epithelium. Dysfunction of motile cilia has been linked to human diseases, especially primary ciliary dyskinesia (PCD). Despite their clinical importance, little is known about the key molecules and signaling pathways that govern motile ciliogenesis and ciliated cell differentiation. Therefore, understanding these fundamental biological phenomena is crucial for developing novel therapeutic strategies for the prevention and treatment of PCD and other cilia-related disorders. Chibby (Cby) was originally isolated as an evolutionarily conserved antagonist of the Wnt/¿-catenin signaling pathway. Cby physically interacts with the pivotal downstream coactivator ¿-catenin and inhibits ¿-catenin-mediated transcriptional activation. Intriguingly, Cby-knockout (Cby-/-) mice suffer from recurrent respiratory infections due to a complete absence of mucociliary transport activity, reminiscent of PCD. Our studies further revealed that ciliated cells in the nasal and lung epithelia of Cby-/- mice are poorly differentiated characterized by a markedly decreased number of motile cilia. Consistent with this phenotype, we found that endogenous Cby protein localizes to the base of cilia. Our findings therefore establish that Cby plays an essential role in proper formation/function of motile cilia in the respiratory tract. However, the cellular and molecular bases underlying the ciliary defects of Cby-/- mice remain largely unexplored. In addition, whether the ciliogenic function of Cby relates to Wnt/¿-catenin signaling is unclear. The goal of this proposal is to elucidate the roles of Cby, Cby-interacting proteins and Wnt/ ¿-catenin signaling in motile ciliogenesis and tracheal ciliated cell differentiation. In order to achieve this goal, we propose the following Specific Aims: Specific Aim 1. Investigate the role of Cby in tracheal ciliated cell differentiation; Specific Aim 2. Examine transcriptional regulation of the Cby gene during differentiation of tracheal ciliated cells; Specific Aim 3. Isolate Cby-binding partners and define their roles in ciliated cell differentiation. We expect that these experiments will contribute to a fundamental understanding of the molecular and cellular mechanisms of ciliogenesis and ciliated cell differentiation. PUBLIC HEALTH RELEVANCE: Motile cilia (tiny hair-like projections from ciliated cells) lining our respiratory tract wave back and forth to effectively remove inhaled debris and microorganisms entrapped in mucus, and human patients with dysfunctional cilia suffer from recurrent respiratory infections, leading to respiratory insufficiency. Therefore, understanding mechanisms of motile cilia formation and ciliated cell differentiation is critical for development of new therapies for diseases caused by dysfunctional cilia. Our research investigates roles of Chibby protein and Wnt signaling pathway in motile cilia formation and ciliated cell differentiation, and will most likely contribute to our better understanding of these important biological processes.