Craig S S, Reckelhoff J F, Bond J S
Department of Anatomy, Virginia Commonwealth University, Richmond 23298-0001.
Am J Physiol. 1987 Oct;253(4 Pt 1):C535-40. doi: 10.1152/ajpcell.1987.253.4.C535.
An inherited deficiency of a metalloendopeptidase (meprin) activity occurs in kidneys of many inbred mouse strains. To clarify whether meprin protein is present in low-activity strains and determine the distribution of meprin in kidneys of mice with high- and low-meprin activities, kidney slices were stained through the use of the indirect immunoperoxidase technique and examined by light and electron microscopy. Light microscopy at high dilutions of anti-meprin IgG confirmed the brush border localization of meprin in high-meprin activity strains and revealed no detectable cross-reactive material in low-meprin activity strains. However, light and electron microscopy studies that use lower dilutions of anti-meprin immunoglobulin G (IgG) revealed cross-reactivity in low-activity strains, also at the luminal surface of the proximal tubules. Studies at lower magnifications indicated that meprin is primarily associated with the juxtamedullary region of the kidney in both high- and low-activity strains. Western blots of urinary proteins showed significant amounts of meprin-like proteins, but only in the urine of mice with high-meprin activity. The low activity of meprin in some inbred mouse strains is not associated with the presence of the protein in compartments of kidney cells other than the brush border or with secretion of the protein into the urine.
许多近交系小鼠的肾脏中存在金属内肽酶（meprin）活性的遗传性缺陷。为了阐明低活性品系中是否存在meprin蛋白，并确定meprin在高meprin活性和低meprin活性小鼠肾脏中的分布，通过间接免疫过氧化物酶技术对肾脏切片进行染色，并通过光学显微镜和电子显微镜进行检查。在高稀释度的抗meprin IgG下进行光学显微镜检查，证实了meprin在高meprin活性品系中的刷状缘定位，并显示在低meprin活性品系中未检测到交叉反应物质。然而，使用较低稀释度的抗meprin免疫球蛋白G（IgG）进行的光学显微镜和电子显微镜研究显示，低活性品系中也存在交叉反应，同样在近端小管的管腔表面。较低放大倍数下的研究表明，在高活性和低活性品系中，meprin主要与肾脏的近髓区域相关。尿蛋白的蛋白质印迹显示存在大量meprin样蛋白，但仅在高meprin活性小鼠的尿液中。某些近交系小鼠品系中meprin的低活性与除刷状缘外的肾细胞区室中该蛋白的存在或该蛋白分泌到尿液中无关。
