Elucidation of the mechanism of essential hypertension making a transgenic mice made by putative kallikrein binding protein

激肽激酶是激肽原加工释放激肽的关键酶，激肽具有利尿和利钠作用。对激肽激酶活性的调控了解甚少。最近，Chao等人在人类和大鼠中发现了一种组织特异性的钾化钙素结合蛋白，可以抑制钾化钙素的活性。随后克隆了大鼠和小鼠的钾化钾素结合蛋白的编码基因。众所周知，原发性高血压患者肾钾likrein-kinin系统受到抑制。Western blot和Northern blot分析表明肾脏中存在钾likrein结合蛋白。我们采用反转录和聚合酶链反应的方法，利用显微解剖方法检测肾元上钾化钾素结合蛋白的精确定位。SD大鼠的信号以内髓集管最为丰富，外髓集管、近曲小管和肾小球的信号较少。在WKY中也有类似的分布，而在SHR中仅在髓内集管中检测到少量。肾元末端存在钾化钾素结合蛋白，提示该蛋白在调节体液和血压方面的重要性。为了探究该蛋白在原发性高血压发病机制中的作用，我们进一步尝试通过转基因小鼠过表达小钾likrein结合蛋白。目前我们正在进行全长基因的分离并在小鼠体内表达。

Kallikrein is a key enzyme in the processing of kininogen to release kinins, which exert diuretic and natriuretic actions. The regulation of kallikrein activities is poorly understood. Recently, Chao et al have identified a tissue specific kallikrein-binding protein that inhibits kallikrein activity, in human and rat. The gene coding for kallikrein-binding protein of rat and mouse has been subsequently cloned. It is well known that the renal kallikrein-kinin system is depressed in essential hypertension. The presence of kallikrein-binding protein in the kidney has been suggested by Western blot and Northern blot analysis. We used reverse-transcription and polymerase chain reaction to detect the precise localization of kallikrein-binding protein along the nephron using the microdissection method. In SD rats, the most abundant signals were found in inner medullary collecting duct, with small amount in outer medullary collecting duct, proximal convoluted tubule, and glomerulus. Similar distribution was found in WKY,however, in SHR,only a small amount was detected in inner medullary collecting duct. The presence of kallikrein-binding protein in terminal segment of the nephron suggests the importance of this protein in the regulation of body fluid and probably blood pressure. To explore the role of this protein in the mechanism of essential hypertension, we further tried to make transgenic mice to over-express the kallikrein-binding protein. Now we are processing the isolation of full length gene and express it to mice.