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

描述(由申请人提供)：本建议的目的是确定关键信号分子在决定伤口修复过程中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，这一事实需要广泛的防御能力。上呼吸道疾病是损伤反应信号异常和伤口修复缺陷的结果。基底层细胞介导的创面修复经历了两个阶段：1)基底层细胞增殖以实现再上皮化，2)基底层细胞分化以形成功能上皮。我的初步数据表明，2-连环蛋白稳定核信号会导致缺乏分化细胞的上皮的发育，而2-连环蛋白减少核信号对基底细胞分化是允许的。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组成的三方复合体介导的，并允许伤口修复过程中的基底细胞分化。为了检验中心假设，这项提议涉及三个具体目标。1)验证单体角蛋白14在14-3-3相互作用区域的苏氨酸和丝氨酸残基上被磷酸化，并受蛋白激酶C调节的假说。2)检验2-连环蛋白、14-3-3与CHIBBY相互作用调节2-连环蛋白亚细胞定位的假说。3)验证2-连环素缺失的基底细胞不分化为分泌细胞或纤毛细胞，导致基底细胞增生、分泌细胞和纤毛细胞发育不良的假说。这项建议旨在更好地理解呼吸系统疾病缓解与进展过程中涉及的调控机制。这项拟议的研究有望为伤口修复过程中的基底细胞信号转导提供机械学上的见解。了解创伤修复过程中的信号事件可能会导致在临床上操纵呼吸道疾病的解决/进展的新靶点。 公共卫生相关性：肺部疾病，如支气管肺发育不良、慢性肺部疾病、囊性纤维化、哮喘和特发性肺纤维化，其特征是呼吸道重构。在这些疾病中，通常有一个异常伤口愈合的组成部分，其特征是特化(分化)细胞的丧失和表现为扁平形态的细胞(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机制可能导致治疗分子靶点，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.