TGF-alpha mRNA expression in renal organogenesis: a study in rat and human embryos

The peptides belonging to the epidermal growth factor (EGF) family play a significant role in kidney development by binding the EGF receptor. Transforming growth factor-alpha (TGF alpha), a member of this family, is thought to be the fetal ligand of the EGF receptor. The present study aims to localize the TGF alpha transcripts in rat and human embryonic kidneys using a nonradioactive in situ hybridization method on paraffin-embedded embryonic samples. The results obtained in this study, beside demonstrating the usefulness of the nonradioactive technique for the detection of TGF alpha mRNA in paraffin sections, allowed TGF alpha-producing cells to be seen in developing kidneys. TGF alpha mRNA and its respective peptide were found in the primitive mesonephric structures and within metanephric blastema and ureteric bud cells. The presence of the TGF alpha gene transcript in the developing rat and human kidney suggests that the TGF alpha peptide is of embryonic origin and that it may contribute to renal organogenetic processes together with other growth factors.