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Expression of transforming growth factor-alpha mRNA and peptide in rodent kidneys
1Child Health Research Institute, North Adelaide, South Australia, Australia.
Abstract:
The expression and function of transforming growth factor alpha (TGF-(alpha) in the kidney are not fully characterised. There exists controversy concerning the detection of renal TGF-alpha mRNA and the localisation of its immunoreactivity. In attempts to clarify the detection and localisation issue, the present study aimed to detect TGF-alpha mRNA in neonate and adult rat kidneys, to examine the specificity of two commonly used anti-TGF-alpha antibodies and finally to localise renal TGF-alpha immunoreactivity using a specific antibody. TGF-alpha mRNA of around 4.8 kb was readily detected with a sensitive nonradioactive northern analysis, with a similar abundance in neonatal and adult rat kidneys. Renal TGF-alpha peptide of the 6-kDa mature form was identified by western blotting. By using various controls, including specimens from TGF-alpha knock out mice in comparison with wild-type mice, the present study has confirmed the specificity of a polyclonal anti-human recombinant TGF-alpha antibody. With this antibody, TGF-alpha immunoreactivity was localised to the proximal tubules in renal cortex. In addition, the 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.
Insights
Transforming growth factor alpha (TGF-α) mRNA and peptide are present in rat kidneys. Specific antibodies reveal TGF-α localized to proximal tubules, clarifying its renal expression.
Area of Science:
- Nephrology
- Molecular Biology
- Immunohistochemistry
Background:
- The expression and function of transforming growth factor alpha (TGF-α) in the kidney remain incompletely understood.
- Controversy exists regarding the detection of renal TGF-α mRNA and the localization of its immunoreactivity.
Purpose of the Study:
- To detect TGF-α mRNA in neonatal and adult rat kidneys.
- To examine the specificity of two commonly used anti-TGF-α antibodies.
- To localize renal TGF-α immunoreactivity using a specific antibody.
Main Methods:
- Sensitive nonradioactive northern analysis for mRNA detection.
- Western blotting to identify the mature TGF-α peptide.
- Specificity testing of antibodies using TGF-α knockout and wild-type mice.
Main Results:
- TGF-α mRNA (~4.8 kb) was detected in both neonatal and adult rat kidneys at similar abundance.
- The 6-kDa mature form of TGF-α peptide was identified by western blotting.
- A polyclonal antibody confirmed specificity and localized TGF-α immunoreactivity to proximal tubules.
- A commonly used monoclonal antibody showed non-specificity, staining collecting ducts.
Conclusions:
- TGF-α is expressed in rat kidneys at both mRNA and peptide levels.
- Proximal tubules are identified as the primary site of TGF-α immunoreactivity in the renal cortex.
- The specificity of antibodies is critical for accurate TGF-α localization in renal research.