In situ hybridization of human kidney tissue reveals cell-type-specific expression of the O6-methylguanine-DNA methyltransferase gene.

The cell-type-specific expression of human O6-methylguanine-DNA methyltransferase (O6-MT) was determined in paraffin-embedded sections of human kidney. A 39 base oligomer complementary to O6-MT cDNA was labeled with digoxigenin and visually detected in situ using an alkaline phosphatase-conjugated anti-digoxigenin antibody. This allowed direct determination of O6-MT-specific mRNA levels, while simultaneously identifying the structures and cell types in the kidney section. Expression of O6-MT was high in distal tubular and glomerular epithelial cells and low in the cells of the Bowman's capsule, collecting and proximal tubular cells. Hybridization of the oligomer was specific to RNA, since RNase and not DNase eliminated the signal. Expression was uniform in all the cell types, except the glomerular cells exhibited varying levels of high intensity. Cell-specific expression was constant between tissue sections from the same and different kidney tissues. These data may help explain the differential response of various cell types to alkylating agents.