Overby L H, Gardlik S, Philpot R M, Serabjit-Singh C J
Laboratory of Cellular and Molecular Pharmacology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina.
Lab Invest. 1994 Apr;70(4):468-78.
Glutathione S-transferases detoxify a broad range of exogenous compounds, but are important also in the metabolism of endogenous compounds. Physiologically relevant substrates are the endoperoxide and hydroperoxide metabolites of arachidonic acid that play important roles in many tissues including the kidney.
We used immunohistochemical and immunoblotting techniques in a systematic study of renal localization of four rabbit enzymes that represent three major mammalian cytosolic glutathione S-transferase classes, alpha, pi, and mu.
The two alpha-class enzymes (rbGST alpha I, rbGST alpha II) were distributed discretely in kidney, ureter, and bladder, while pi and mu were widely distributed in the renal system. Immunohistochemical localization in paraffin sections with antibodies specific for rbGST alpha I or rbGST alpha II demonstrated that no compartment of the renal system contained both enzymes. Collecting ducts of the inner medulla and all epithelial cells of the kidney pelvis, ureter, and bladder contained rbGST alpha I. All cells lining proximal tubules contained rbGST alpha II. No other compartment of the renal system exhibited immunoreactivity with anti-rbGST alpha II. Antibody specific for pi reacted with cells lining nephrons, ureter, and bladder and with endothelial cells throughout the renal system. Localization of pi was most prominent in the collecting ducts of medulla and in the epithelial cells lining the kidney pelvis, ureter, and bladder. As anti-mu did not react in tissue sections, distribution of mu was determined by immunoblotting. Immunoblots of cytosolic preparations from whole kidney, cortex, medulla, and epithelia of ureter, bladder, and kidney pelvis were prepared and tested with each of the 4 antibodies. This second localization method confirmed the distribution data from tissue sections for rbGST alpha I, rb GST alpha II, and pi; also, it demonstrated that the staining observed in tissue was specifically for each enzyme. mu was detected in all the renal cytosolic preparations except those from the epithelium of the kidney pelvis.
The discrete renal distribution of rbGST alpha I and rbGST alpha II and their distinct catalytic activities with prostaglandin substrates suggest important roles for these enzymes in prostaglandin-dependent renal functions.
谷胱甘肽S-转移酶可使多种外源性化合物解毒，但其在内源性化合物的代谢中也很重要。生理相关底物是花生四烯酸的内过氧化物和氢过氧化物代谢产物，它们在包括肾脏在内的许多组织中发挥重要作用。
我们使用免疫组织化学和免疫印迹技术，对代表三种主要哺乳动物胞质谷胱甘肽S-转移酶类别（α、π和μ）的四种兔酶进行肾脏定位的系统研究。
两种α类酶（rbGSTαI、rbGSTαII）在肾脏、输尿管和膀胱中呈离散分布，而π和μ在泌尿系统中广泛分布。用针对rbGSTαI或rbGSTαII的特异性抗体对石蜡切片进行免疫组织化学定位表明，泌尿系统的任何区域都不含有这两种酶。内髓集合管以及肾盂、输尿管和膀胱的所有上皮细胞都含有rbGSTαI。近端小管的所有内衬细胞都含有rbGSTαII。泌尿系统的其他区域均未显示出与抗rbGSTαII的免疫反应性。针对π的特异性抗体与肾单位、输尿管和膀胱的内衬细胞以及整个泌尿系统的内皮细胞发生反应。π的定位在髓质集合管以及肾盂、输尿管和膀胱的上皮细胞中最为显著。由于抗μ在组织切片中不发生反应，因此通过免疫印迹确定μ的分布。制备了来自全肾、皮质、髓质以及输尿管、膀胱和肾盂上皮细胞的胞质提取物的免疫印迹，并使用4种抗体中的每一种进行检测。这种第二种定位方法证实了组织切片中rbGSTαI、rbGSTαII和π的分布数据；此外，它还表明在组织中观察到的染色是每种酶特有的。除了肾盂上皮细胞的提取物外，在所有肾脏胞质提取物中均检测到了μ。
rbGSTαI和rbGSTαII在肾脏中的离散分布以及它们对前列腺素底物的独特催化活性表明这些酶在前列腺素依赖性肾脏功能中发挥重要作用。
