KINASE REGULATION OF THE EPITHELIAL NA CHANNEL

存在于某些肾上皮细胞（肾单位的远端部分）中的Na通道对于肾脏的Na重吸收至关重要。 该通道的调节是一种重要的机制，不仅影响最终尿钠组成，而且影响全身钠稳态。 1993年和1994年克隆了该通道的三个亚基。 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，了解该通道的调节对于了解某些类型的通道相关高血压疾病至关重要。 该通道受激素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及其与天然上皮中发现的激酶调节的关系的理解才刚刚开始。 初步数据表明，克隆和天然通道的激酶调节之间的差异，这一发现可能归因于该通道的其他未克隆亚基的存在。 此外，还缺乏对天然通道的PKC调节的详细了解。PKC参与多种细胞反应，从通道活性调节到程序性细胞死亡（凋亡）。 这种PKC作用的多样性归因于具有不同细胞功能的多种PKC异构体的存在。 已经确定PKC及其各种亚型是通过多种细胞信号级联调节该通道的中心，这些细胞信号级联由激素和其他第二信使启动。然而，对它们在上皮中的功能知之甚少，对它们对Na+通道的作用也一无所知。 本项目涉及阐明不同的PKC亚型在克隆通道调节中的作用。 该提案的长期目标是提供对通道调节的重要领域的更好的深入理解，沿着鉴定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可能导致高血压的某些类型的通道功能障碍铺平道路，仅在美国就有近6000万人患有高血压。

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.