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Electrofocusing analysis of DNA polymerase beta in hypophysectomized rat testis
A Nagasaka1, S Yoshida, T Ohyama
1Department of Internal Medicine, Fujita Health University School of Medicine, Toyoake, Aichi, Japan.
Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme
|April 1, 1990
Summary
Pituitary hormones and testosterone influence DNA polymerase beta enzyme activity in rat testes, specifically affecting a peak at pH 8.2. This enzyme modification is unique to the testes and not observed in the brain.
Area of Science:
- Biochemistry
- Molecular Biology
- Endocrinology
Background:
- DNA polymerase beta (beta-enzyme) plays a crucial role in DNA repair.
- The activity and isoforms of beta-enzyme can be modulated by various physiological factors.
- Pituitary hormones and androgens are known regulators of testicular function.
Purpose of the Study:
- To investigate the effect of hypophysectomy on the isoelectric focusing profiles of DNA polymerase beta in rat testes and brain.
- To determine the role of gonadotropins and testosterone in reconstituting the affected beta-enzyme activity in testes.
Main Methods:
- Isoelectric focusing was employed to separate and quantify DNA polymerase beta enzyme activity.
- Experiments were conducted on sham-operated and hypophysectomized rats.
- Hormonal treatments (gonadotropins and testosterone) were administered to hypophysectomized rats.
Main Results:
- In sham-operated rat testes, three peaks of beta-enzyme activity were observed at pH 7.1, 8.2, and 9.1.
- Hypophysectomy resulted in the loss of the pH 8.2 beta-enzyme peak in rat testes.
- Treatment with gonadotropins and testosterone restored the pH 8.2 beta-enzyme peak in hypophysectomized rat testes.
- Hypophysectomy did not alter the isoelectric focusing profiles of beta-enzyme in rat brain.
Conclusions:
- The beta-enzyme activity in rat testes exhibits distinct isoforms that are sensitive to pituitary hormone regulation.
- The beta-enzyme peak at pH 8.2 in testes is specifically regulated by pituitary hormones and testosterone.
- These findings suggest that pituitary hormones play a role in modulating DNA polymerase beta activity in the testes through post-translational modifications or differential expression.