THE PRIMARY CILIUM OF CONECTIVE TISSUE CELLS: INCIDENCE AND ORIENTATION

描述（由申请人提供）：现在已经确定，在身体的大多数细胞上存在一种修饰的，非活动的初级纤毛，作为天线感应细胞外环境，无论是管状器官的管腔还是结缔组织的细胞外基质。初级纤毛最终转导刺激，导致基因表达，控制细胞的基本生物学反应。在过去的五年中，人们对初级纤毛作为全身上皮细胞中的感觉细胞器的作用的了解有了显著的增加，其中最大的突破来自于发现与特定疾病有关的初级纤毛的某些异常，如幼儿多囊肾病。

DESCRIPTION (provided by applicant): It is now well established that on most cells of the body there exists a modified, non-motile primary cilium that acts as an antenna sensing the extracellular environment, be it the lumen of a tubular organ or the extracellular matrix of connective tissues. The primary cilium ultimately transduces stimuli that result in gene expression controlling fundamental biological responses of the cell. In the past five years there has been a significant increase in the understanding to the role of the primary cilium as a sensory organelle in epithelial cells throughout the body, with the greatest breakthroughs coming from discovering certain abnormalities of the primary cilium that are linked to specific diseases, such as polycystic kidney disease in young children. For parallel advancements to be made in understanding the functional role of the primary cilium in cells of connective tissues, methodology must be developed that allows easy detection of primary ciliary incidence and orientation, in vitro and in vivo. In epithelia, the primary cilium of each cell projects into the lumen of the organ or to the surface of a monolayer culture. In this superficial position its presence and orientation can be analyzed by light microscopical techniques following experimental manipulation. Primary cilia have been described as present in chondrocytes, tenocytes, and other connective tissue cells, but experimental analysis of their function remains a significant challenge because 1) the cilium projects into the extracellular matrix, and 2) many connective tissue cells do not maintain phenotypic stability in long-term monolayer culture. The goal of this proposal is to develop rapid versatile analytical methods based on imaging using multiphoton microscopy to examine the incidence, orientation and molecular structure of the primary cilium in articular cartilage, growth plate, tendon and intervertebral disc. This methodology will put the exploration of the function of the primary cilium in connective tissues on par with that of its counterpart in epithelial tissues. Establishment of this methodology will open the potential for exploring the function of the primary cilium of connective tissue cells in vivo through analysis of the cilium 1) in mouse models with chondrodysplasias thought to be linked to abnormalities in development of cellular polarity and tissue organization; 2) during development when anisotropy of cell and matrix organization of connective tissues is being established; and 3) in experiments in living animals involving manipulation of the biomechanical environment associated with a specific joint. An ability to assess rapidly the incidence and orientation of the primary cilium will provide a methodology that currently is missing for analysis of results from in vitro experimentation at the molecular level to test the hypothesis that the primary cilium of connective tissue cells functions as a mechanosensor.