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过程中决定基底细胞增殖或分化命运的作用。肺是为数不多的与外界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。基底细胞介导的伤口修复分为两个阶段：1)基底细胞增殖以实现再上皮化；2)基底细胞分化以形成功能性上皮。我的初步数据表明，2-catenin稳定的核信号导致上皮缺乏分化细胞的发育，2-catenin减少的核信号有利于基底细胞分化。我们假设细胞质中2-连环蛋白的隔离是由14-3-3、chibby和磷酸化角蛋白14组成的三方复合体介导的，并且在伤口修复过程中允许基底细胞分化。为了验证中心假设，本提案提出了三个具体目标。1)验证角蛋白14单体在14-3-3相互作用区域苏氨酸和丝氨酸残基上被磷酸化，磷酸化受蛋白激酶c调控的假说。2)验证2-catenin、14-3-3和chibby的相互作用调节2-catenin亚细胞定位的假说。3)验证2-catenin缺失的基底细胞不分化为分泌细胞和纤毛细胞，导致基底细胞增生和分泌细胞和纤毛细胞发育不全的假设。本研究旨在更好地理解呼吸系统疾病消退与进展的调控机制。拟议的研究有望为伤口修复过程中基底细胞信号传导的机制提供见解。了解伤口修复过程中的信号事件可能会导致新的靶点，从而在临床上操纵呼吸系统疾病的解决/进展。

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.