Developmental Physiology of Ciliated Epithelia

描述（由申请人提供）：在许多器官系统中，上皮产生强有力的纤毛流，沿着腔面运输生物材料，这种流动的丧失对人类健康有重大影响。例如，呼吸道是纤毛上皮，其流动用于运输保护性黏液层，也是组织损伤后清理肺部的机制。因此，呼吸道纤毛流的丧失是慢性哮喘、囊性纤维化和慢性阻塞性肺疾病发病的一个因素。尽管纤毛上皮对人类健康很重要，但其发育和功能背后的细胞和分子机制在很大程度上仍是未知的。我们建议使用一个可处理的模型系统——爪蟾幼虫皮肤来研究这些机制。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，幼虫皮肤含有特殊的上皮细胞类型，这是纤毛上皮的标志，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运输酸/碱的细胞。使用这个模型，提出的实验将解决两个目标。在第一个目标中，提出了实验来确定定向纤毛细胞使其在同一方向上跳动的机制。纤毛细胞的这种特性被称为平面细胞极性，是产生沿着适当组织轴方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位的模式线索，以及流动在完善纤毛细胞定位中的作用。在第二个目标中，提出了实验来确定参与酸/碱运输的细胞形成的机制。这些细胞直接类似于肾脏中的插层细胞，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，以及这些细胞如何特化以分泌质子或碱当量碳酸盐。这些目的中概述的实验结果将提供关于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，对诊断和治疗引起纤毛粘膜运输缺陷和pH失调的人类疾病具有重要意义。公共卫生相关性：特化上皮通过在肺和女性生殖道等器官中产生纤毛流，在人类健康中发挥重要作用，但在胚胎发生过程中，构成这些上皮的特化细胞类型如何形成，在很大程度上仍然未知。该研究将使用非洲爪蟾幼虫皮肤作为模型系统，以确定两种特殊上皮细胞类型形成的发育机制，即多纤毛细胞和产生流体流动的细胞和介导酸/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的人类疾病，如慢性哮喘、囊性纤维化和慢性阻塞性肺疾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.