Developmental Physiology of Ciliated Epithelia

描述（由申请人提供）：在许多器官系统中，上皮细胞产生沿着管腔表面沿着运输生物材料的有力纤毛流动，并且该流动的损失对人类健康具有重要意义。例如，呼吸道是一种纤毛上皮，其中流动用于运输保护性粘液层和组织损伤后清除肺部的机制。因此，呼吸道中纤毛流动的丧失是慢性哮喘、囊性纤维化和慢性阻塞性肺病发病的促成因素。尽管它们对人类健康的重要性，纤毛上皮细胞的发育和功能的细胞和分子机制仍然是未知的。我们建议研究这些机制使用一个易于处理的模型系统，爪蟾幼虫皮肤。幼虫的皮肤是胚胎发育过程中最早形成的器官之一，可以很容易地成像，并且非常容易进行遗传分析。此外，幼虫皮肤含有作为纤毛上皮细胞的标志的特化上皮细胞类型，包括专门产生纤毛流的多纤毛细胞、专门产生粘液的细胞和专门用于酸/碱运输的细胞。使用这个模型，所提出的实验将解决两个目标。在第一个目标中，提出了实验来确定纤毛细胞定向的机制，以便在同一方向上跳动。纤毛细胞的这种特性称为平面细胞极性，它是产生沿沿着适当组织轴定向的长距离流动的能力的基础。这些实验将剖析纤毛细胞形成时定向的图案线索，以及流动在细化纤毛细胞定向中的作用。在第二个目标中，提出实验来确定参与酸/碱运输的细胞形成的机制。这些细胞直接类似于肾脏中的嵌入细胞，其在pH调节中起关键作用。这些实验将确定转录因子在这些细胞形成中的作用，以及这些细胞如何变得专门分泌质子或碱等价物碳酸盐。这些目标中概述的实验结果将提供有关纤毛上皮中发现的特化细胞类型的形成和功能的基本信息，对诊断和治疗导致粘液纤毛转运和pH失调缺陷的人类疾病具有意义。公共卫生相关性：特化上皮细胞通过在肺和女性生殖道等器官中产生纤毛流动，在人类健康中发挥着重要作用，但构成这些上皮细胞的特化细胞类型在胚胎发生过程中如何形成仍在很大程度上未知。拟议的研究将使用非洲爪蟾幼虫皮肤作为模型系统，以确定两种专门的上皮细胞类型形成的基础发育机制，即多纤毛细胞和产生流体流动的细胞以及介导酸/碱运输的细胞。更好地了解这些细胞类型将有助于诊断和治疗影响纤毛上皮细胞的人类疾病，如慢性哮喘，囊性纤维化和慢性阻塞性肺病期间发生的粘液清除缺陷。

DESCRIPTION (provided by applicant): In many organ systems, epithelia produce a vigorous ciliary flow that transports biological materials along luminal surfaces and a loss of this flow has significant implications for human health. The respiratory tract, for instance, is a ciliated epithelium where flow is used to transport a protective mucus layer and a mechanism for clearing the lung after tissue damage. As a consequence, loss of ciliary flow in the respiratory tract is a contributing factor to morbidity in chronic asthma, cystic fibrosis, and chronic obstructive pulmonary disease. Despite their importance to human health, the cellular and molecular mechanisms that underlie the development and function of ciliated epithelia are still largely unknown. We propose to study these mechanisms using a tractable model system, the Xenopus larval skin. The larval skin is one of the earliest organs to form during embryonic development, can be easily imaged, and is extremely tractable to a genetic analysis. In addition, the larval skin contains specialized epithelia cell types that are the hallmark of ciliated epithelia, including the multi-ciliate cells specialized to produce ciliary flow, cells specialized to produce mucus, and cells specialized for acid/base transport. Using this model, the proposed experiments will address two Aims. In the first Aim, experiments are proposed to determine the mechanisms that orient ciliated cells so that beat in the same direction. This property of ciliated cells, called planar cell polarity, underlies the ability to produce long range flow that is directed along the appropriate tissue axis. These experiments will dissect the patterning cues that orient ciliated cells when they form, and the role of flow in refining ciliated cell orientation. In the second Aim, experiments are proposed to determine the mechanisms that underlie the formation of cells involved in acid/base transport. These cells are directly analogous to the intercalated cells in the kidney, which play critical roles in pH regulation. These experiments will determine the role of transcription factors in the formation of these cells, and how these cells become specialized to secrete protons or the base equivalent, carbonate. The results from the experiments outlined in these Aims will provide basic information about the formation and function of specialized cells types found in ciliated epithelia, with implications for the diagnosis and treatment of human diseases that cause defects in mucociliary transport and pH mis-regulation. PUBLIC HEALTH RELEVANCE: Specialized epithelia play important roles in human health by generating ciliary flow in such organs as the lung and the female reproductive tract but how the specialized cell types that make up these epithelia form during embryogenesis remains largely unknown. The proposed research will use the Xenopus larval skin as a model system to determine the developmental mechanisms that underlie the formation of two specialized epithelial cell types, namely cells that are multi-ciliated and produce fluid flow and cells that mediate acid/base transport. A better understanding of these cell types will aid in the diagnosis and treatment of human disease that affect ciliated epithelia, such as the mucus clearance defects that occurs during chronic asthma, cystic fibrosis, and chronic obstructive pulmonary disease.