Expression of transforming growth factor-alpha mRNA and peptide in rodent kidneys

The expression and function of transforming growth factor alpha (TGF-alpha) in the kidney are not fully characterised. There exists controversy concer ning the detection of renal TGF-alpha mRNA and the localisation of its immu noreactivity. In attempts to clarify the detection and localisation issue, the present study aimed to detect TGF-alpha mRNA in neonate and adult rat k idneys, to examine the specificity of two commonly used anti-TGF-alpha anti bodies and finally to localise renal TGF-alpha immunoreactivity using a spe cific antibody. TGF-alpha mRNA of around 4.8 kb was readily detected with a sensitive non radioactive northern analysis, with a similar abundance in n eonatal and adult rat kidneys. Renal TGF-alpha peptide of the 6-kDa mature form was identified by western blotting. By using various controls, includi ng specimens from TGF-alpha knock out mice in comparison with wildtype mice , the present study has confirmed the specificity of a polyclonal anti-huma n recombinant TGF-alpha antibody. With this antibody, TGF-alpha immunoreact ivity was localised to the proximal tubules in renal cortex. In addition, t he present study has also demonstrated a non-specificity in localising TGF- alpha in rodent kidneys by the most commonly used monoclonal anti-human TGF -alpha C-terminal peptide antibody, which stained collecting ducts in renal cortex and medulla.