In situ hybridization of prepro-epidermal growth factor mRNA in the mouse kidney.

The presence of prepro-epidermal growth factor (prepro-EGF) mRNA was studied in the mouse kidney by in situ hybridization using [3H]prepro-EGF cDNA and 35S-labeled prepro-EGF cRNA probes. In addition, anti-EGF serum was utilized to immunolocalize the peptide by the avidin-biotin complex immunoperoxidase method. Both EGF immunoreactivity and prepro-EGF mRNA hybridization were localized to the thick ascending limb of Henle (TAL) and the distal convoluted tubule (DCT), whereas the macula densa was negative. The glomerulus, the proximal portion of the nephron, and the collecting system were negative. Computer-assisted image analysis of the optical density of the autoradiographic and immunocytochemical signals were performed. The medullary TAL expressed significantly less prepro-EGF than the cortical TAL and the DCT.