| Summary: | 碩士 === 國防醫學院 === 生物化學研究所 === 106 === Kidney is a crucial organ which is responsible for blood filtration, removing nitrogen waste, and acid-base balance of the blood, each kidney is composed by around a million tiny units called nephrons. Prostasin is glycosylphosphatidylinositol (GPI)-anchored to the apical surface of different epithelial cells including the renal collecting duct principal cells. In kidney, prostasin is also called Channel-Activating Protease-1 (CAP1) which was described that epithelial sodium channels (ENaC) γ subunit could be activated by prostasin to increase urinary Na+ influx on distal convoluted tubule and collecting duct. Matriptase is type 2 transmembrane serine protease and expressed primarily in different epithelial cells. Matriptase is involved in many physiological processes, including skin differentiation, embryonic growth and skin barrier function. In previous reports, matriptase could activate downstream substrates through it proteolytic cleavage, like HGF, PAR2, even prostasin. The activated matriptase and prostasin are tightly regulated by the hepatocyte growth factor activator inhibitor (HAI)-1 and HAI-2. However, HAI-1 and HAI-2 specifically inhibit matriptase or prostasin in kidney is still not clear. This study aims to discover the functions of matriptase, prostasin, HAI-1 and HAI-2 in kidney. In this study, the location of matriptase, prostasin, and HAI-1/2 are in Henle’s loop, distal tubule, and collecting duct. Our results were confirmed by IHC. Besides, the colocalization of matriptse-HAI-1 and prostasin-HAI-2 were also confirmed. We further investigated the shedding of activated matriptase, prostasin, and their complex by detecting the urine from healthy human. However, the proteases and their inhibitors were decreased tremendously in the urine from patient with kidney diseases. Therefore we can examine renal function by detecting matriptase, prostasin, HAI-1, and HAI-2 in urine. Then we treat HK-2 cell, an immortalized cell line of proximal tubule, and found that matriptase were activated under environment stress in this cell line. The molecule weigh of matriptase complex in HK-2 cell were consistent with patients’ urine, but prostasin were not activated. Therefore, the activated matriptase is associated with kidney diseases. According to our results, matriptase and prostasin could have their specific functions in kidney. We expect to learn the possible roles of matriptase and prostasin in the near future.
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