Höfer D, Drenckhahn D
Department of Anatomy, Julius-Maximilians-University, Würzburg, Germany.
Histochemistry. 1993 Jan;99(1):29-35. doi: 10.1007/BF00268017.
The present study addressed the question as to whether the four different actin-associated proteins that are associated with the actin core bundle in intestinal microvilli (i.e. villin, fimbrin, myosin I and ezrin) are essential components of all microvilli of the body. The retina provides an excellent example of a tissue supplied with three different sets of microvilli, namely those of Müller's glial cells (Müller baskets), photoreceptors (calycal processes), and pigment epithelial cells. The main outcome of this study is that none of these microvilli contain all four actin-associated proteins present in intestinal microvilli. Müller cell microvilli contain villin, ezrin and myosin I (95 kDa isoform) but not fimbrin. Calycal processes of photoreceptors contain fimbrin but not villin, myosin I and ezrin. Finally, microvilli of pigment epithelial cells are positive for ezrin but not for villin, fimbrin and myosin I. Because of limited cross-reactivities of the antibodies to myosin I and ezrin, the myosin I data refer to the chicken retina whereas the findings with anti-ezrin were obtained with the rat retina. A further outcome of this study is that the actin filament core bundles in microvilli of chicken pigment epithelial cells are presumed to contain a crosslinking protein, which is not immunologically related to either villin, fimbrin or myosin I of the intestinal brush border.
本研究探讨了与肠微绒毛肌动蛋白核心束相关的四种不同肌动蛋白结合蛋白（即绒毛蛋白、丝束蛋白、肌球蛋白I和埃兹蛋白）是否为身体所有微绒毛的必需成分这一问题。视网膜是一个很好的例子，它有三种不同类型的微绒毛，即米勒神经胶质细胞的微绒毛（米勒篮）、光感受器的微绒毛（杯状突）和色素上皮细胞的微绒毛。本研究的主要结果是，这些微绒毛均不含有肠微绒毛中存在的全部四种肌动蛋白结合蛋白。米勒细胞微绒毛含有绒毛蛋白、埃兹蛋白和肌球蛋白I（95 kDa异构体），但不含有丝束蛋白。光感受器的杯状突含有丝束蛋白，但不含有绒毛蛋白、肌球蛋白I和埃兹蛋白。最后，色素上皮细胞的微绒毛埃兹蛋白呈阳性，但绒毛蛋白、丝束蛋白和肌球蛋白I呈阴性。由于针对肌球蛋白I和埃兹蛋白的抗体交叉反应性有限，肌球蛋白I的数据来自鸡视网膜，而抗埃兹蛋白的研究结果来自大鼠视网膜。本研究的另一个结果是，推测鸡色素上皮细胞微绒毛中的肌动蛋白丝核心束含有一种交联蛋白，该蛋白与肠刷状缘的绒毛蛋白、丝束蛋白或肌球蛋白I均无免疫相关性。
