KINASE REGULATION OF THE EPITHELIAL NA CHANNEL

某些肾上皮细胞(肾单位的远端部分)存在的钠通道对肾脏重吸收钠是至关重要的。该通道的调节不仅是影响尿钠最终成分的重要机制，也是影响全身钠稳态的重要机制。该通道的三个亚基分别于1993年和1994年被克隆。这导致发现该通道的突变可导致某些类型的高血压疾病。因此，了解这一经络的调节对于理解某些类型的经络相关高血压疾病至关重要。这个通道受到荷尔蒙和体液因素的高度调节。这些调节模式涉及第二信使蛋白和激酶，如蛋白激酶A和C(PKA和PKC)。对克隆通道的激酶调节以及它与天然上皮细胞的关系的了解才刚刚开始。初步数据表明，克隆通道和天然通道的激酶调节存在差异，这一发现可能归因于该通道没有其他未克隆的亚基。此外，对本地通道的PKC调控也缺乏详细的了解。PKC参与多种细胞反应，从调节通道活性到细胞程序性死亡(细胞凋亡)。PKC作用的这种多样性归因于多种具有不同细胞功能的PKC亚型的存在。众所周知，PKC及其各种异构体是由激素和其他第二信使启动的各种细胞信号级联反应调节该通道的中心。然而，人们对它们在上皮细胞中的功能知之甚少，也没有人知道它们对钠通道的影响。本项目致力于阐明不同的PKC亚型在调控克隆通道中的作用。这项建议的长期目标是更好地深入了解通道调节的一个重要领域，以及识别与克隆通道相互作用的其他分子。这些结果将为更好地了解某些类型的渠道功能障碍铺平道路，这些功能障碍可能导致高血压，仅在美国就有近6000万人受到影响。

The Na channel present in certain kidney epithelia (distal portion of the nephron) is critical to Na reabsorption by the kidneys. Regulation of this channel is an important mechanism that not only affects the final urine Na composition but also total body Na homeostasis. Three subunits of this channel were cloned in 1993 and 1994. This lead to the discovery that mutations of this channel can result in certain types of hypertensive diseases. Thus, an understanding of the regulation of this channel is critical in understanding certain types of channel-related hypertensive diseases. This channel is highly regulated by hormonal and humoral factors. These mode of regulation involve second messenger proteins and kinases, such as protein kinase A and C (PKA and PKC). An understanding of kinase regulation of the cloned channel and its relationship to that found in native epithelia is just beginning. Preliminary data indicates differences between the kinase regulation of the cloned and native channels, a finding that may be attributed to the absence of other uncloned subunits of this channel. Moreover, a detailed understanding of the PKC regulation of the native channel is also lacking. PKC has been implicated in a variety of cellular responses, ranging from the regulation of channel activity to programmed cell death (apoptosis). This diversity of actions of PKC are attributed to the existence of multiple PKC isoforms with distinct cellular functions. It is well established that PKC and its various isoforms are central to the regulation of this channel by a variety of cell signaling cascades, initiated by hormones and other second messengers. However, little is known about their function in epithelia, and none is known about their effect on Na+ channels. This project deals with the elucidation of the roles of the different PKC isoforms in regulation of the cloned channels. The Long term objectives of this proposal are to provide a better in-depth understanding of an important area of channel regulation, along with identification of additional molecules that interact with the cloned channel. These results will pave the way for a better understanding of certain types of channel dysfunction that could result in hypertension, a disease that affects nearly 60 million individuals in the US alone.