Regulation of transport mechanisms in lens cells

描述（由申请方提供）：透镜细胞利用Na，K-ATP酶 保持稳定的细胞质组成，从而保持透明性。为了 克服离子调节的困难，在这样一个大质量的紧密 透镜是特化的，使得上皮细胞，特别是 在透镜赤道部，Na，K-ATP酶保持高活性，而纤维细胞 Na，K-ATP酶活性低。这种Na，K-ATPase的不均匀分布 活动是重要的，因为它提供了循环的动力。 离子电流在后极向外流动，在前极向内流动， 柱然而，我们对不平等的空间 确定了Na，K-ATP酶活性的定位，因为所有的透镜细胞， 上皮和纤维具有相似的Na，K-ATP酶蛋白丰度。的 透镜细胞Na，K-ATPase蛋白表达水平与Na， K-ATPase活性。其他因素似乎也参与其中。在这里，我们计划研究如何 上皮细胞获得并维持高Na，K-ATP酶活性。研究 将进行研究之间的联系，钠，钾-ATP酶的活性和 透镜上皮细胞合成新的Na，K-ATP酶蛋白的能力 I）;确定Na，K-ATP酶的氧化翻译后修饰是否 蛋白质有助于降低Na，K-ATP酶活性（目的II）;以及 确定a亚基的酪氨酸磷酸化是否能导致 Na，K-ATP酶活性的变化（目的III）。这些研究的结果将 使我们更好地了解透镜离子调节和透镜细胞 支持长期保持透镜透明度的专门化。

DESCRIPTION (provided by applicant): Lens cells utilize Na, K-ATPase to preserve stable cytoplasmic composition and thus transparency. In order to overcome the difficulty of ion regulation in such a large mass of tightly packed cells, the lens is specialized such that epithelial cells, particularly at the lens equator, maintain a high activity of Na, K-ATPase while fiber cells have low Na, K-ATPase activity. This unequal distribution of Na, K-ATPase activity is important because it provides the driving force for circulating ionic currents that flow outward at the posterior pole, inward at the anterior pole. However there is a gap in our knowledge of how the unequal spatial localization of Na, K-ATPase activity is established because all lens cells, epithelium and fibers, have a similar abundance of Na, K-ATPase protein. The level of Na, K-ATPase protein expression in lens cells does not tally with Na, K-ATPase activity. Other factors seem to be involved. Here we plan to study how the epithelial cells achieve and maintain high Na, K-ATPase activity. Studies will be conducted to examine the link between activity of Na, K-ATPase and the ability of lens epithelial cells to synthesize new Na, K-ATPase protein (Aim I); determine whether oxidative posttranslational modification of Na, K-ATPase protein contributes to reduction of Na, K-ATPase activity (Aim II); and to determine whether tyrosine phosphorylation of the a subunit can bring about changes in Na, K-ATPase activity (Aim III). Results from these studies will give us a better understanding of lens ion regulation and lens cell specializations that underpin long term maintenance of lens transparency.