Walters James W, Dilks Stacie A, DiNardo Stephen
Department of Cell and Developmental Biology, University of Pennsylvania Medical Center, Philadelphia 19104-6058, USA.
Dev Biol. 2006 Sep 15;297(2):323-39. doi: 10.1016/j.ydbio.2006.04.454. Epub 2006 Apr 27.
Epithelial planar cell polarity (PCP) allows epithelial cells to coordinate their development to that of the tissue in which they reside. The mechanisms that impart PCP as well as effectors that execute the polarizing instructions are being sought in many tissues. We report that the epidermal epithelium of Drosophila embryos exhibits PCP. Cells of the prospective denticle field, but not the adjacent smooth field, align precisely. This requires Myosin II (zipper) function, and we find that Myosin II is enriched in a bipolar manner, across the parasegment, on both smooth and denticle field cells during denticle field alignment. This implies that actomyosin contractility, in combination with denticle-field-specific effectors, helps execute the cell rearrangements involved. In addition to this parasegment-wide polarity, prospective denticle field cells express an asymmetry, uniquely recognizing one cell edge over others as these cells uniquely position their actin-based protrusions (ABPs; which comprise each denticle) at their posterior edge. Cells of the prospective smooth field appear to be lacking proper effectors to elicit this unipolar response. Lastly, we identify fringe function as a necessary effector for high fidelity placement of ABPs and show that Myosin II (zipper) activity is necessary for ABP placement and shaping as well.
上皮平面细胞极性（PCP）使上皮细胞能够将自身发育与所在组织的发育协调起来。许多组织都在探寻赋予PCP的机制以及执行极化指令的效应器。我们报告称，果蝇胚胎的表皮上皮表现出PCP。预期形成齿状结构区域的细胞，而非相邻的平滑区域的细胞，精确排列。这需要肌球蛋白II（拉链）发挥作用，并且我们发现，在齿状结构区域排列过程中，肌球蛋白II以双极方式在副节两侧的平滑区域和齿状结构区域细胞中富集。这意味着肌动球蛋白收缩力与齿状结构区域特异性效应器共同作用，有助于执行相关的细胞重排。除了这种副节范围内的极性，预期形成齿状结构区域的细胞还表现出一种不对称性，这些细胞在将基于肌动蛋白的突起（ABP；每个齿状结构均由其构成）独特地定位在其后缘时，能独特地识别一条细胞边缘，而不是其他边缘。预期形成平滑区域的细胞似乎缺乏引发这种单极反应的合适效应器。最后，我们确定边缘蛋白功能是ABP高保真定位所必需的效应器，并表明肌球蛋白II（拉链）活性对于ABP的定位和塑形也必不可少。
