Santos-Bredariol Andréa Silveira, Belmonte Mônica Aparecida, Kihara Alexandre Hiroaki, Santos Marinilce Fagundes, Hamassaki Dânia Emi
Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-900, Brazil.
J Comp Neurol. 2006 Feb 20;494(6):976-85. doi: 10.1002/cne.20861.
Among several small Rho GTPases observed in the chick retina, RhoB was transiently expressed during development and mainly present in glial Müller cells in the adult. The aim of this study was to compare the distribution of RhoB in the chick and mouse adult retinas and to study its potential role in the maintenance of cell morphology. The distribution of RhoB was studied in situ and pure Müller cell cultures were submitted to Clostridium difficile toxin A and lysophosphatidic acid (LPA) treatment in order to inactivate and activate Rho proteins, respectively. Cell morphology, F-actin arrangement, RhoB, and vimentin distribution were studied by immunofluorescence and confocal microscopy. The results showed that, in both species, all vimentin-containing cells also expressed RhoB in situ and in vitro. Toxin A promoted cell rounding and detachment due to actin depolymerization, changing the distribution of RhoB only in chick cells. In serum-starved cells LPA stimulated actin polymerization and cell spreading, but only in chick cells was RhoB distribution recruited to expanding cellular processes and newly formed focal adhesions. These data suggest that, although RhoB is expressed by Müller cells in chick and mouse, its role in the maintenance of cellular morphology and regulation may be different. In addition, we show that RhoB may be an interesting Müller cell marker in the adult retina.
在鸡视网膜中观察到的几种小Rho GTP酶中，RhoB在发育过程中短暂表达，在成体中主要存在于神经胶质Müller细胞中。本研究的目的是比较RhoB在鸡和小鼠成体视网膜中的分布，并研究其在维持细胞形态方面的潜在作用。通过原位研究RhoB的分布，并将纯Müller细胞培养物分别用艰难梭菌毒素A和溶血磷脂酸（LPA）处理，以分别使Rho蛋白失活和激活。通过免疫荧光和共聚焦显微镜研究细胞形态、F-肌动蛋白排列、RhoB和波形蛋白分布。结果表明，在这两个物种中，所有含波形蛋白的细胞在原位和体外也都表达RhoB。毒素A由于肌动蛋白解聚而促进细胞变圆和脱离，仅在鸡细胞中改变RhoB的分布。在血清饥饿的细胞中，LPA刺激肌动蛋白聚合和细胞铺展，但仅在鸡细胞中，RhoB分布被募集到扩展的细胞突起和新形成的粘着斑中。这些数据表明，尽管RhoB在鸡和小鼠的Müller细胞中都有表达，但其在维持细胞形态和调节方面的作用可能不同。此外，我们表明RhoB可能是成体视网膜中一种有趣的Müller细胞标志物。
