Regulation of transport mechanisms in lens cells

描述（由申请人提供）：我们刚刚开始了解任何组织（不仅仅是透镜）如何调节Na，K-ATP酶活性。我们实验室的工作使我们认为透镜Na，K-ATP酶活性可以通过依赖于酪氨酸磷酸化的机制进行微调。这可能是Na，K-ATP酶活性空间分布的基础。它还可以使透镜增加前上皮或纤维某些区域中休眠的Na，K-ATP酶的活性。导致Na，K-ATP酶活性变化的机制涉及Src酪氨酸激酶，并且可以通过从透镜本身释放的激动剂如ATP或内皮素-1来启动。一些激动剂引起Na，K-ATP酶活性的增加，而另一些激动剂引起抑制，即使酪氨酸磷酸化参与两种反应。在这个建议中，我们提出了一个计划来测试的假设，导致Na，K-ATP酶的激活和抑制的信号通路涉及不同的Src激酶，与Na，K-ATP酶。在寻求理解Src酪氨酸激酶和Na，K-ATP酶之间的相互作用时，我们提出研究以弄清楚Src家族激酶活化和Na，K-ATP酶活性调节如何适合于其他信号传导事件（例如瞬时细胞质钙升高）的背景。具体目标是：（1）检验Src激酶家族的不同成员参与刺激性和抑制性Na，K-ATP酶活性反应的假设。(2)确定Src激酶激活在导致受体激活后Na，K-ATP酶活性改变的信号事件序列中的位置。(3)研究Src-Na，K-ATPase相互作用如何影响透镜功能。通过对透镜Na，K-ATPase的研究，我们希望获得的信息将有助于我们在将来计划实验来解释为什么透镜钠-钾稳态在人类皮质性白内障中失败。 公共卫生豁免。 透镜细胞利用Na，K-ATP酶维持稳定的胞质离子组成。Na，K-ATP酶活性的调节是重要的，因为当离子组成异常时，晶状体变得不透明。我们实验室的工作使我们认为，透镜有一个精细调节Na，K-ATP酶活性的优雅系统。我们想知道更多关于这个机制是如何工作的，以及它是如何影响透镜功能的。初步研究告诉我们，该机制涉及Src酪氨酸激酶。在这里，我们提出的研究，以了解Src激酶和Na，K-ATP酶之间的相互作用。

DESCRIPTION (provided by applicant): We are just beginning to understand how any tissue, not just lens, regulates Na,K-ATPase activity. Work in our laboratory causes us to think lens Na,K- ATPase activity can be fine tuned by a mechanism dependent on tyrosine phosphorylation. This may underlie the spatial distribution of Na,K-ATPase activity. It also may enable the lens to increase the activity of dormant Na,K- ATPase in the anterior epithelium or in some regions of the fibers. The mechanism leading to a change of Na,K-ATPase activity involves Src tyrosine kinases and can be set in motion by agonists like ATP or endothelin-1 that are released from the lens itself. Some agonists cause an increase of Na,K-ATPase activity while others cause inhibition even though tyrosine phosphorylation is involved in both responses. In this proposal we present a plan to test the hypothesis that the signaling pathways leading to Na,K-ATPase activation and inhibition involve different Src kinases that associate with Na,K-ATPase. In seeking to understand the interaction between Src tyrosine kinases and Na,K- ATPase we propose studies to figure out how Src-family kinase activation and Na,K-ATPase activity modulation fit in the context of other signaling events such as the transient cytoplasmic calcium rise. The specific aims are: (1) Test the hypothesis that different members of the Src kinase family are involved in stimulatory and inhibitory Na,K-ATPase activity responses. (2) Determine where Src kinase activation fits in the sequence of signaling events that leads to altered Na,K-ATPase activity following receptor activation. (3) Study how Src-Na,K- ATPase interactions affect lens function. By studying lens Na,K-ATPase we hope to obtain information that will help us plan experiments in the future to explain why lens sodium-potassium homeostasis fails in human cortical cataract. PUBLIC HEALTH RELEVEANCE. Lens cells utilize Na, K-ATPase to maintain a stable cytoplasmic ion composition. Regulation of Na,K-ATPase activity is important because lenses become opaque when the ion composition is abnormal. Work in our laboratory causes us to think the lens has an elegant system for fine tuning Na,K-ATPase activity. We want to know more about how the mechanism works and how it affects lens function. Pilot studies tell us the mechanism involves Src tyrosine kinases. Here we propose studies to understand the interaction between Src kinases and Na,K-ATPase.