Deoxyribonucleic acid repair and apoptosis in testicular germ cells of aging fertile men: the role of the poly(adenosine diphosphate-ribosyl)ation pathway

Objective

To explore the relationship between men's age and DNA damage repair proteins related to apoptosis in human testicular germ cells.

Design

Retrospective case–control study.

Setting

Academic institutions.

Patient(s)

Testicular specimens were obtained from 22 fertile volunteers aged 20–82 years.

Intervention(s)

Deoxyribonucleic acid repair markers were assessed using immunohistochemical staining for the cell proliferation marker [proliferating cell nuclear antigen (PCNA)]; DNA repair markers [poly(adenosine diphosphate-ribose) polymerase-1 (PARP-1), poly(adenosine diphosphate-ribose) (PAR), X-ray repair cross-complementing1(XRCC1), and apurinic/apyrimidinic endonuclease 1 (APE1)]; and apoptosis-associated markers (caspase 9, active caspase 3, and cleaved PARP-1).

Main Outcome Measure(s)

The prevalence and cellular localization of the above markers in testicular tissues of young, middle aged, and old men.

Result(s)

Statistically significant differences in DNA damage repair–associated proteins (PARP-1, PAR, XRCC1, and APE1), and apoptosis markers (caspase 9, active caspase 3, and cleaved PARP-1) were observed in testicular samples from older men. These differences were most marked in spermatocytes.

Conclusion(s)

The study demonstrates that there is an age-related increase in human testicular germ cell DNA break repair and apoptosis with age.

Key Words: Aging, DNA repair, apoptosis, germ cells, PARP-1, caspase