GLUTATHIONE TRANSFERASES OF CLASS-ALPHA, CLASS-MU AND CLASS-PI SHOW SELECTIVE EXPRESSION IN DIFFERENT REGIONS OF RAT-KIDNEY

1. Glutathione transferases (GST) are mainly cytosolic and occur in mu ltiple forms, which can be arranged in three distinct, structural clas ses. The different enzyme forms show distinct substrate specificities with electrophilic and genotoxic substances. The expression of the alp ha subunits 1, 2 and 8, the mu subunits 3, 4 and 6, and the pi subunit 7 of GST in different parts of the rat kidney was determined immunohi stochemically. 2. GST immunoreactivity was present predominantly in th e nephron, collecting duct and urothelium. 3. A conspicuous finding wa s that subunits 1, 2 and 8 were localized to the proximal tubules, whi le the mu subunit 3 was demonstrable in epithelial tubular cells from the distal tubules to the urothelium. The immunoreactivity of subunits 4 and 6 could be visualized in epithelial cells from the ascending th in limb to the collecting ducts. Subunit 7 was found in the thin limb of the loop of Henle, and in scattered cells in the distal tubules. 4. The urothelial cells covering the papilla and the renal calyces showe d immunoreactivity to GST subunits 2-4 and 6-8. 5. Thus, in the nephro n the class alpha GSTs were selectively expressed in the proximal tubu les and the class mu and class pi GST in the thin loop of Henle and di stal tubules. The cells in the collecting ducts and the urothelium, wh ich have a different ontogeny than the nephron, do not show any corres ponding differential distribution of the GST classes. 6. Cells in a gi ven location were in some cases found to be non-reactive with a given antiserum in an otherwise immunoreactive cell population, demonstratin g a spatial variation in GST expression. The immunoreactivity to the d ifferent forms of GST was predominantly cytoplasmic but a nuclear loca lization could also be demonstrated. 7. The panel of antibodies to GST may tentatively be used as markers in localizing lesions in restricte d parts of the nephrons and to elucidate dynamic alterations in the tu bular system in response to physiological and toxic agents.