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New androgen-stimulated proteins in the kidneys of female mice
Abstract:
Testosterone administration to female mice for 25 days produced a 70% increase in total kidney protein in both A/J and C57BL/6J mice. This is in contrast to the known androgen-responsive proteins, such as beta-glucuronidase and alcohol dehydrogenase, which each represent less than 1% of the total kidney proteins even after maximum stimulation. To investigate this discrepancy, we initiated a study to identify major proteins which increase with androgen treatment. Three new cytoplasmic proteins designated T1, T2, and T3 were found in different subcellular fractions of both A/J and C57BL/6J mice. T1 (43,000 daltons) and T2 (60,000 daltons) were found in the mitochondrial-lysosomal fraction of 25-day androgen-treated mice. T3 (54,000 daltons) was found in the microsomal fraction. Each of these proteins increased several-fold during androgen treatment, so that they were easily identified using sodium dodecyl sulfate polyacrylamide gel electrophoresis. By contrast, no major changes were noted in the soluble proteins. A nonhistone chromosomal protein of 54,000 mol wt (T4) was found in chromatin preparations from androgen-stimulated A/J mice. Additional studies with androgen-insensitive Tfm/Y mice and with various hormones indicated that stimulation of the T proteins was dependent on androgenic steroid and a functional androgen receptor.
Insights
Testosterone treatment significantly increased kidney protein in mice by identifying three novel proteins (T1, T2, T3). These androgen-responsive proteins are key to understanding testosterone
Area of Science:
- Endocrinology
- Molecular Biology
- Biochemistry
Background:
- Testosterone administration to female mice increased total kidney protein by 70%.
- Known androgen-responsive proteins represent <1% of kidney proteins, suggesting other proteins are involved.
Purpose of the Study:
- Identify major kidney proteins that increase with androgen treatment.
- Investigate the discrepancy between total protein increase and known androgen-responsive proteins.
Main Methods:
- Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used to identify and quantify proteins.
- Subcellular fractionation isolated proteins from mitochondrial-lysosomal and microsomal fractions.
- Chromatin preparations were analyzed for nonhistone chromosomal proteins.
Main Results:
- Three novel cytoplasmic proteins (T1, T2, T3) were identified in different subcellular fractions.
- T1 (43 kDa) and T2 (60 kDa) were found in the mitochondrial-lysosomal fraction; T3 (54 kDa) in the microsomal fraction.
- A 54 kDa nonhistone chromosomal protein (T4) was identified in chromatin from androgen-stimulated mice.
- Protein stimulation was androgen-dependent and required a functional androgen receptor, as shown in Tfm/Y mice.
Conclusions:
- Testosterone significantly increases specific kidney proteins beyond known androgen-responsive enzymes.
- Novel proteins T1, T2, T3, and T4 are major androgen-induced proteins in mouse kidney.
- These findings highlight new targets for understanding androgenic effects in the kidney.