Basal Cell Differentiation by Keratin 14 Cytosolic Sequestration of Beta-Catenin

描述（由申请人提供）：本提案的目的是确定关键信号分子在伤口修复期间决定基底细胞增殖或分化命运中的作用。肺是少数几个与外部环境直接接触的人体器官系统之一，这需要广泛的防御能力。上呼吸道疾病是异常损伤反应信号传导和缺陷性伤口修复的结果。基底细胞介导的伤口修复发生在两个阶段：1）用于再上皮化目的的基底细胞增殖，和2）用于功能性上皮发育的基底细胞分化。我的初步数据表明，2-catenin的核信号的稳定导致上皮细胞的发展，缺乏分化的细胞，并减少核信号的2-catenin是允许的基底细胞分化。我们假设2-连环蛋白的细胞质隔离是由14-3-3，chibby和磷酸角蛋白14组成的三方复合物介导的，并且允许伤口修复过程中的基底细胞分化。为了检验中心假设，本提案提出了三个具体目标。1)为了验证以下假设：单体角蛋白14在14-3-3相互作用结构域中的苏氨酸和丝氨酸残基上被磷酸化，并且磷酸化受蛋白激酶C调节。2)检验2-连环蛋白、14-3-3和chibby之间的相互作用调节2-连环蛋白的亚细胞定位的假设。3)为了检验2-catenin无效的基底细胞不分化为分泌或纤毛细胞，导致基底细胞增生和分泌和纤毛细胞发育不全的假设。 该提案旨在更好地了解呼吸系统疾病缓解与进展中涉及的调节机制。预期所提出的研究将为伤口修复期间的基底细胞信号传导提供机制性见解。伤口修复过程中信号事件的知识可能会导致新的目标，通过该目标在临床上操纵呼吸系统疾病的解决/进展。 公共卫生相关性：肺疾病如支气管肺发育不良、慢性肺疾病、囊性纤维化、哮喘和特发性肺纤维化的特征在于气道重塑。在这些疾病中，通常存在异常伤口愈合的成分，其特征是特化（分化）细胞的丢失和表现出扁平形态的细胞（未分化的基底细胞）的增加。深入了解促进基底细胞分化的信号传导机制可能会导致治疗分子靶点，可用于缓解和/或解决与上皮重塑相关的呼吸系统疾病。

DESCRIPTION (provided by applicant): The purpose of this proposal is to identify the role of key signaling molecules in determining the proliferation or differentiation fate of basal cells during wound repair. The lung is one of few human organ systems to have direct contact with the external environment, a fact that necessitates extensive defense capacities. Upper respiratory diseases are the result of aberrant injury response signaling and defective wound repair. Basal cell-mediated wound repair occurs in two stages: 1) basal cell proliferation for the purpose of re-epithelialization, and 2) basal cell differentiation for development of a functional epithelium. My preliminary data indicate that stabilization of nuclear signaling by 2-catenin results in the development of an epithelium that lacks differentiated cells, and that decreased nuclear signaling by 2-catenin is permissive for basal cell differentiation. We hypothesis that cytoplasmic sequestration of 2-catenin is mediated by a tripartite complex composed of 14-3-3, chibby, and phospho-keratin 14 and is permissive for basal cell differentiation during wound repair. To test the central hypothesis, three Specific Aims are addressed in this proposal. 1) To test the hypothesis that monomeric keratin 14 is phosphorylated on threonine and serine residues in the 14-3-3 interaction domain, and phosphorylation is regulated by protein kinase C. 2) To test the hypothesis that interactions between 2-catenin, 14-3-3, and chibby regulate subcellular localization of 2-catenin. 3) To test the hypothesis that 2-catenin null basal cells do not differentiate into secretory or ciliated cells, resulting in basal cell hyperplasia and secretory and ciliated cell hypoplasia. This proposal seeks to better understand regulatory mechanisms involved in respiratory disease resolution vs. progression. The proposed studies are expected to provide mechanistic insight to basal cell signaling during wound repair. Knowledge of signaling events during wound repair may lead to novel targets by which to manipulate respiratory disease resolution/progression in the clinic. PUBLIC HEALTH RELEVANCE: Lung diseases such as bronchopulmonary dysplasia, chronic pulmonary disease, cystic fibrosis, asthma, and idiopathic pulmonary fibrosis are characterized by airway remodeling. In these diseases, there is often a component of aberrant wound healing, characterized by the loss of specialized (differentiated) cells and an increase in cells that exhibit a flattened morphology (non-differentiated basal cells). Insight into signaling mechanisms that promote basal cell differentiation may lead to therapeutic molecular targets that can be used to alleviate and/or resolve respiratory diseases associated with epithelial remodeling.