Câmpean Valentina, Theilig Franziska, Paliege Alex, Breyer Matthew, Bachmann Sebastian
Anatomisches Institut, Charité, Humboldt Universität, Berlin, Germany.
Am J Physiol Renal Physiol. 2003 Jul;285(1):F19-32. doi: 10.1152/ajprenal.00443.2002. Epub 2003 Mar 25.
Prostanoids derived from endogenous cylooxygenase (COX)-mediated arachidonic acid metabolism play important roles in the maintenance of renal blood flow and salt and water homeostasis. The relative importance of COX-1 and COX-2 isoforms is under active investigation. We have performed a comprehensive histochemical analysis by comparing rat and mouse kidneys for cellular and subcellular localization of COX-1 and -2 and microsomal-type PGE synthase (PGES), the rate-limiting biosynthetic enzyme in PGE2 synthesis. A choice of different sera was compared, and the results were confirmed by antigen-retrieval techniques, in situ hybridization, RT-PCR, and the use of COX knockout mice. In the glomerulus, significant COX-1 expression was detected in a subset of mesangial cells. Along the renal tubule, the known COX-2 expression in cTAL and macula densa was paralleled by PGES staining. In the terminal distal convoluted tubule, connecting tubule, and cortical and medullary collecting ducts, a significant COX-1 signal was colocalized with PGES; COX-2 was not found in these sites. Intercalated cells were generally negative. Cortical fibroblasts were COX-1 and PGES positive in mice, whereas in rats only PGES could be reliably detected. Lipid-laden interstitial cells of the inner medulla were COX-1, -2, and PGES positive. Vascular smooth muscle cells were not stained. The present data support prominent functions of renal prostanoids, predominantly PGE2, by defining expression sites of the key enzymes for their biosynthesis in the rat and mouse. Results define the renal cell types involved in prostaglandin autacoid functions within spatially restricted sites such as the juxtaglomerular apparatus, mesangium, distal convolutions and collecting duct, and in compartments of the renal interstitium.
内源性环氧化酶（COX）介导的花生四烯酸代谢产生的前列腺素类物质在维持肾血流量以及盐和水平衡方面发挥着重要作用。COX-1和COX-2同工型的相对重要性正在积极研究中。我们通过比较大鼠和小鼠肾脏中COX-1、COX-2以及微粒体型前列腺素E合酶（PGES，前列腺素E2合成中的限速生物合成酶）的细胞和亚细胞定位，进行了全面的组织化学分析。比较了不同血清的选择，并通过抗原修复技术、原位杂交、逆转录聚合酶链反应（RT-PCR）以及使用COX基因敲除小鼠来证实结果。在肾小球中，在一部分系膜细胞中检测到显著的COX-1表达。沿肾小管，已知在皮质升支粗段和致密斑中的COX-2表达与PGES染色平行。在终末远曲小管、连接小管以及皮质和髓质集合管中，显著的COX-1信号与PGES共定位；在这些部位未发现COX-2。闰细胞通常为阴性。小鼠皮质成纤维细胞COX-1和PGES呈阳性，而在大鼠中仅能可靠检测到PGES。髓质内层充满脂质的间质细胞COX-1、COX-2和PGES呈阳性。血管平滑肌细胞未染色。本研究数据通过确定大鼠和小鼠中前列腺素类物质生物合成关键酶的表达位点，支持了肾前列腺素类物质（主要是前列腺素E2）的突出功能。结果确定了在诸如肾小球旁器、系膜、远曲小管和集合管等空间受限部位以及肾间质隔室中参与前列腺素类自分泌功能的肾细胞类型。
