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Expression of Hsp70-2 in rhesus monkey testis during germ cell apoptosis induced by testosterone undecanoate
Xin-Chang Zhou1, Zhi-Hong Zhang, Zhao-Yuan Hu
1State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
Abstract:
Hsp70-2 functions as a molecular chaperone that assists other proteins in their folding, transport and assembly into complexes, and is postulated to be linked to the mechanisms that inhibit apoptosis. Here we have determined the association between Hsp70-2 gene and germ cell apoptosis induced by a high dose of testosterone undecanoate (TU). In this study, in situ analysis of cell DNA fragmentation and expression of Hsp70-2 in TU-treated monkey testes were compared with the normal testes. The TUNEL analysis data showed that a large number of germ cell apoptosis occurred in the testes on Day 30 after TU injection. Therefore, we speculate that spermatogenesis failure in TU-treated monkey testis may be a result of the germ cell apoptosis induced by a high dose of TU. As compared with that of normal testes, however, the level of Hsp70-2 mRNA was only slightly decreased while that of Hsp70-2 protein was almost unchanged in the testes from Day 7 to day 30 at the early stage of the germ cell apoptosis after TU treatment, but the levels of both Hsp70-2 mRNA and protein dropped dramatically on Day 60 when a large number of germ cells had undergone apoptosis and were depleted. Therefore, it is suggested that the Hsp70-2 may be not a molecule to prevent germ cell apoptosis induced by injection of TU in the testes at the early stage.
Insights
High doses of testosterone undecanoate (TU) induce germ cell apoptosis in monkey testes. Heat shock protein 70-2 (Hsp70-2) levels do not prevent early-stage germ cell apoptosis, suggesting a limited role in mitigating TU-induced effects.
Area of Science:
- Reproductive biology
- Molecular biology
- Cellular stress response
Background:
- Heat shock protein 70-2 (Hsp70-2) acts as a molecular chaperone involved in protein folding and assembly.
- Hsp70-2 is implicated in mechanisms that inhibit apoptosis.
- Testosterone undecanoate (TU) is used to suppress spermatogenesis, but its effects on germ cell apoptosis and Hsp70-2 require investigation.
Purpose of the Study:
- To investigate the association between the Hsp70-2 gene and germ cell apoptosis induced by high-dose testosterone undecanoate (TU) in monkey testes.
- To compare DNA fragmentation and Hsp70-2 expression in TU-treated versus normal monkey testes.
Main Methods:
- In situ analysis of DNA fragmentation using TUNEL assay.
- Quantitative assessment of Hsp70-2 mRNA and protein expression levels.
- Comparison between testes from TU-treated monkeys and normal control monkeys at various time points (Day 7, 30, and 60 post-injection).
Main Results:
- Significant germ cell apoptosis was observed in monkey testes by Day 30 after TU injection.
- Hsp70-2 mRNA levels showed a slight decrease, while Hsp70-2 protein levels remained largely unchanged during the early stages (Day 7-30) of TU-induced germ cell apoptosis.
- Both Hsp70-2 mRNA and protein levels decreased dramatically by Day 60, coinciding with extensive germ cell depletion.
Conclusions:
- High-dose TU induces significant germ cell apoptosis in monkey testes, potentially leading to spermatogenesis failure.
- Hsp70-2 does not appear to play a protective role against early-stage germ cell apoptosis induced by TU.
- The observed decrease in Hsp70-2 levels at later stages suggests a potential consequence rather than a preventative mechanism against TU-induced germ cell apoptosis.