Regulation of transport mechanisms in lens cells

描述(申请人提供)：我们刚刚开始了解任何组织，而不仅仅是晶状体，是如何调节Na，K-ATPase活性的。我们实验室的工作使我们认为晶状体Na，K-ATPase的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-ATPase活性空间分布的基础。它还可以使晶状体前上皮或纤维某些区域休眠的Na，K-ATPase活性增加。导致Na，K-ATPase活性改变的机制涉及Src酪氨酸激酶，并可由晶状体本身释放的激动剂如ATP或ET-1启动。一些激动剂引起Na，K-ATPase活性增加，而另一些激动剂则引起抑制，尽管这两种反应都涉及酪氨酸磷酸化。在这个提议中，我们提出了一个计划来检验这一假设，即导致Na，K-ATPase激活和抑制的信号通路涉及与Na，K-ATPase相关的不同的Src激酶。为了了解Src酪氨酸激酶和Na，K-ATPase之间的相互作用，我们提出了一些研究，以弄清楚Src家族的激酶激活和Na，K-ATPase活性调节如何适用于其他信号事件，如短暂的细胞质钙升高。其具体目的是：(1)验证不同的Src激酶家族成员参与刺激和抑制Na，K-ATPase活性反应的假设。(2)确定在受体激活后导致Na，K-ATPase活性改变的信号事件序列中，Src激酶激活的位置。(3)研究Src-Na、K-ATPase相互作用对晶状体功能的影响。通过对晶状体Na，K-ATPase的研究，我们希望获得的信息将有助于我们计划未来的实验，以解释人类皮质性白内障晶状体钠钾稳态失败的原因。公共卫生保障。晶状体细胞利用Na，K-ATPase来维持稳定的细胞质离子组成。调节Na，K-ATPase活性很重要，因为当离子组成异常时，晶状体会变得不透明。我们实验室的工作让我们认为这种晶状体有一个优雅的系统来微调Na，K-ATPase的活性。我们想更多地了解这一机制是如何工作的，以及它是如何影响晶状体功能的。初步研究告诉我们，这种机制与Src酪氨酸激酶有关。在这里，我们提出了一些研究，以了解Src激酶和Na，K-ATPase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.