Tensile stress in orienting planar cell polarity

描述（由申请人提供）：在许多器官系统中，投射数百根跳动纤毛的细胞（称为多纤毛细胞）产生沿着沿着腔表面运输生物材料的有力流体流。多纤毛细胞分布在呼吸道、生殖道和脑室中，它们产生的血流对人类健康有重要意义。为了使器官功能有效，纤毛流动必须沿着特定的轴：例如，在肺中，流动将粘液排出而不是更深地进入气道。为了产生定向流动，发育中的上皮细胞需要获得平面轴，从而使细胞内以及细胞之间的纤毛定向跳动。为了确定多纤毛细胞如何获得平面细胞极性（PCP），我们开创了一个模型系统，即X。平滑幼虫皮肤多纤毛细胞开始分化后不久，在发育中的皮肤，产生一个蓬勃的纤毛流动，总是从前面到后面。在原肠胚形成期间发生的全局模式化事件已知固定纤毛流动的方向，但是对于介导该模式化事件的机制一无所知，如在PCP的所有其他已知实例中的情况。在这个探索性的建议中，我们将测试一个新的模型，其中平面极性的方向部分取决于胚胎发生过程中组织中发生的拉伸应力的方向。在皮肤的情况下，这种张应力在原肠胚形成期间通过中胚层在对合和轴向伸长期间产生的力而发生。具体地说，我们将采用一种称为牵引器拉力的装置，在平面轴正常建立的阶段，向孤立的发育中的皮肤施加定向应力。这些实验将扩展初步的研究结果，确定的参数，定向应力可以指定一个平面轴，并确定是否定向应力工程上游或平行于PCP信号通路。总之，本文提出的实验将提供一个重要的原理证明，从而建立一个新的模型，研究如何在胚胎中的力量造型和图案组织。 公共卫生相关性：多纤毛细胞通过在脑、肺和生殖道中产生定向流体流动而在人类健康中发挥重要作用，但对相对于器官轴定向流动方向的机制知之甚少。为了研究这些机制，拟议的研究将采用一个模型系统来测试一个新的假设，其中由发育中的组织引起的张应力用于定向纤毛流动的方向。从拟议的实验结果将潜在地建立一个新的范式纤毛流动的方向是如何建立在发展过程中，并将有影响人类疾病的诊断和治疗的纤毛上皮细胞，如睫状体缺陷，发生在原发性纤毛运动障碍和卡特格纳综合征。

DESCRIPTION (provided by applicant): In many organ systems, cells projecting hundreds of beating cilia, called multiciliate cells, produce a vigorous fluid flow that transports biological materials along luminal surfaces. Multiciliate cells populate the respiratory and reproductive tracts, and the ventricles of the brain, and the flow they produce has significant implications for human health. To be effective in organ function, ciliary flow has to direct along a specific axis: in the lung, for example, flow propels mucus out of rather than deeper into the airways. To produce directed flow, developing epithelia need to acquire a planar axis, thus orienting cilia beating within a cell, as well as between cells. To determine how multiciliate cells acquire planar cell polarity (PCP), we have pioneered a model system, namely the X. laevis larval skin. Multiciliate cells begin to differentiate in the developing skin soon after gastrulation, producing a vigorous ciliary flow that invariably is directed from anterior to posterior. A global patterning event that occurs during gastrulation is known to fix the direction of ciliary flow, but nothing is known about the mechanisms that mediate this patterning event as is the case in all other known examples of PCP. In this exploratory proposal, we will test a new model where the direction of planar polarity is dictated in part by the orientation of tensile stress that occurs in the tissue during embryogenesis. In the case of the skin, this tensile stress occurs during gastrulation via the forces generated by mesoderm during involution and axial elongation. Specifically, we will employ a device, called the tractor pull, to apply oriented stress to isolated developing skin, at stages when the planar axis is normally established. These experiments will extend on preliminary findings, determine the parameters by which oriented stress can specify a planar axis, and determine whether oriented stress works upstream or in parallel with the PCP signaling pathway. In sum, the experiments proposed here will provide an important proof of principle, thus establishing a new model for studying how forces in the embryo sculpt and pattern tissues. PUBLIC HEALTH RELEVANCE: Multiciliate cells play important roles in human health by generating directed fluid flow in the brain, lung and reproductive tract, but the mechanisms that orient flow direction in relation to an organ axis are poorly understood. To study these mechanisms, the proposed research will employ a model system to test a novel hypothesis where tensile stress incurred by a developing tissue acts to orient the direction of ciliary flow. Results from the proposed experiments will potentially establish a new paradigm for how the direction of ciliary flow is established during development, and will have implications for diagnosis and treatment of human disease that affect ciliated epithelia, such as the ciliary defects that occurs during primary ciliary dyskinesia and Kartegener's syndrome.