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Heat stress reduces poly(ADPR)polymerase expression in rat testis
F Tramontano1, M Malanga, B Farina
1Department of Organic & Biological Chemistry, University Federico II of Naples, Italy.
Molecular Human Reproduction
|June 29, 2000
Summary
Heat stress significantly reduces poly(ADPR)polymerase (PARP) concentration and activity in adult rat testes. Unexpectedly, PARP degradation, a marker of apoptosis, was not observed following heat-induced stress.
Area of Science:
- Reproductive Biology
- Molecular Biology
- Biochemistry
Background:
- Poly(ADPR)polymerase (PARP) is a chromatin enzyme involved in DNA repair.
- PARP activity is high in the testis and linked to germ cell differentiation and apoptosis.
- Heat stress can impact testicular function and cellular processes.
Purpose of the Study:
- To investigate the effects of heat stress on PARP concentration, activity, and associated molecules in adult rat testes.
- To examine changes in poly(ADP-ribose) (pADPR) acceptor proteins and poly(ADPR)glycohydrolase (PARG) activity.
- To determine if PARP degradation, an indicator of apoptosis, occurs after heat stress.
Main Methods:
- Artificial cryptorchidism was used to induce heat stress in adult rats.
- PARP concentration and activity assays were performed.
- PARG activity and pADPR length were analyzed.
- Apoptotic degradation of PARP was assessed.
Main Results:
- A significant decrease in PARP concentration and activity was observed 4 and 8 days post-heat stress.
- No significant changes in PARG activity or pADPR length were detected.
- Apoptotic degradation of PARP was not observed despite heat stress.
Conclusions:
- PARP gene expression is developmentally regulated during spermatogenesis and suppressed by heat stress.
- Heat stress leads to a reduction in PARP levels and activity without inducing its apoptotic degradation.
- The findings suggest a suppression of PARP during the loss of meiotic spermatocytes induced by artificial cryptorchidism.