Aim： To examine the possible effect of heat treatment on expression of heat shock proteins （Hsps） 105, 70, and 60 in primary monkey Sertoli cells and to evaluate the possible signal pathways. Methods： Western blot analysis, realtime polymerase chain reaction （PCR）, and confocal immunohistochemistry were used to analyze mRNA and protein levels of the Hsps in response to 43~C treatment of Sertoli cells isolated from pubertal monkey testes. Results： Staining with Hoechst 33342 indicated Sertoli cells did not undergo apoptosis after heat treatment. Hspl05 was expressed in cytoplasm of untreated Sertoli cells. Both Hspl05 mRNA and protein levels were increased approximately 20-fold compared to those of the untreated controls at 12 h after heat treatment. Untreated Sertoli cells did not express Hsp70, but heat stress induced its expression in the cell cytoplasm. The time-course of changes in Hsp70 was similar to that of Hsp105. In contrast to Hsp105 and Hsp70, the change in Hsp60 expression was much less obvious. The protein level between 12 h and 48 h after heat treatment was only approximately 1.5-fold that of the untreated control. Extracellular regulated kinase （ERK） 1/2 inhibitor （U0126） or phosphoinositide kinase-3 （PI3K） inhibitor （LY294002） could partially block the response of Hspl05 and Hsp70 induced by heat treatment. Conclusion： These results indicate that the heat-induced expression of the three types of Hsp in monkey Sertoli cells might be regulated by ERK and/or PI3K signal pathways, but the profile of their expression is different, suggesting that they might have different regulatory functions in Sertoli cells.
Min Chen Jin-Xiang Yuan Yu-Qiang Shi Xue-Sen Zhang Zhao-Yuan Hu Fei Gao Yi-Xun Liu
Artificial cryptorchidism or local testicular heat treatment can induce reversible oligospermia or azoospermia in monkeys and rats via germ cell apoptosis. Local warming of monkey testes in water at 43°C for 2 consecutive days (30 min per day) decreased the number of sperm in the semen by up to 80% on d 28, and the effect was completely reversed on d 144. Germ cells rely heavily on Sertoli cells for structural and nutritional support. Specialized junctions that play a pivotal role in spermatogenesis occur at sites of Sertoli-Sertoli and Sertoli-germ cell contact in the seminiferous epithelium. We demonstrated that expression of tight junction (TJ)-associated molecules, such as occludin and zonula occludens-1 (ZO-1), were greatly reduced 24–48 h after heat treatment, while the permeability of the blood-testis barrier (BTB) was simultaneously increased, but recovered 10 d later. These results indicate a reversible disruption of the BTB associated with transient inductions of transforming growth factor (TGF) β2 and β3 expression, p38 mitogen-activated protein kinase and extracellular signal-regulated kinase activation, and concomitant loss of occludin and ZO-1. This suggests that expression of TJ-associated molecules and the BTB was reversibly perturbed by mild testicular hyperthermia, and that the heat-induced induction of TGF-β might be involved in downregulating TJ-associated proteins, leading to cell junction reduction. This review discusses the changes in total gene expression patterns after experimental cryptorchidism in adult mouse testes, and the cloning of several novel, physiologically significant spermatogenesis-specific genes.
LIU YiXun & LI XiXia State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
