Uchl1 and its associated proteins were involved in spermatocyte apoptosis in mouse experimental cryptorchidism.

Uchl1 was found to be involved in spermatocyte apoptosis. The aim of the present study was to test whether Uchl1 and its associated proteins Jab1 and p27(kip1) were involved in spermatogenic damages in response to heat-stress in cryptorchidism. Hematoxylin and eosin (HE) staining and DNA end labeling (TUNEL) were used to observe morphological and apoptotic characteristics of spermatogenic cells; Immunohistochemical analysis was used to detect changes of Uchl1 and its associated proteins Jab1 and p27(kip1) in response to heat-stress from cryptorchidism leading to spermatocyte losses; And protein affinity analysis (pull-down) and immunofluorescence co-localization were used to verify the relevance among the three proteins in spermatocytes. The results showed that, Jab1 and p27(kip1), in parallel to Uchl1, increased in spermatocytes of apoptotic appearances in response to heat-stress, but not in multinucleated giant cells; Jab1 bound to Uchl1 in testis protein extracts, and co-localized with Uchl1 and p27(kip1) specifically in spermatocytes with apoptotic appearances. These results suggest that the accumulation of Uchl1 protein is involved in the heat-stress-induced spermatocyte apoptosis through a new pathway related with Jab1 and p27(kip1), but not the formation of multinucleated giant cells.

PTOV1 is associated with UCH-L1 and in response to estrogen stimuli during the mouse oocyte development.

To investigate the biological significance of ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) involvement in oocyte maturation, we screened for proteins that bound to UCH-L1 in mouse ovaries, and we found that the prostate tumor overexpressed-1 (PTOV1) protein was able to bind to UCH-L1. PTOV1 is highly expressed in prostate cancers and considered as a potential marker for carcinogenesis and the progress of prostate cancer. It was reported that PTOV1 plays an important role in cell cycle regulation, but its role in mammalian oocyte development and meiosis is still unclear. In this paper, it was found that the expression levels of PTOV1 in mouse ovaries progressively increased from prepubescence to adulthood. And we found by immunohistochemistry that PTOV1 spreaded in both the cytoplasm and nuclei of oocytes during prepuberty, but in normal adult mouse oocytes, it concentrated not only in nuclei but also on the plasma membrane, though in some oocytes with abnormal shapes, PTOV1 did not display the typical distribution patterns. In granulosa cells, however, it was found to locate in the cytoplasm at all the selected ages. In postnatal mouse ovaries (28 days), estradiol treatment induced the adult-specific distribution pattern of PTOV1 in oocytes. In addition, UCH-L1 was shown to be associated with CDK1, which participated in the regulation of cell cycle and oocyte maturation. Therefore, we propose that the distribution changes of PTOV1 are age-dependent, and significant for mouse oocyte development and maturation. Moreover, the discovery that PTOV1 is associated with UCH-L1 in mouse oocytes supports the explanations for that UCH-L1 is involved in oocyte development and maturation, especially under the regulation of estrogen.

Ubiquitin carboxyl-terminal hydrolase L1 contributes to the oocyte selective elimination in prepubertal mouse ovaries.

Apoptosis of abnormal oocytes is essential for defective oocyte elimination during prepubertal ovary development, and the ubiquitin system regulates the cell apoptosis via the degradation of specific proteins. Ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) is a component of the ubiquitin system, and the UCH-L1-dependent apoptosis is important for spermatogenesis. In the present study, the change in the number of follicles and the expression of UCH-L1 in oocytes were determined in prepubertal mouse ovaries by immunohistochemical techniques. A significant decrease in the follicular pool was found in prepubertal mouse ovaries during the period of day 21 to day 28 after birth, and accordingly, the UCH-L1 protein expression was increased, to some degree in association with Jun activation domain-binding protein 1 (Jab1) and cyclin-dependent kinase inhibitor p27(Kipl). The increased UCH-L1 protein, together with the corresponding changes of Jab1 was detected in morphologically abnormal oocytes of prepubertal ovaries. Through the immunofluorescent colocalization, UCH-L1 was shown concentrating in abnormal oocytes, and a parallel change in Jab1 was also seen. The affinity analysis confirmed the interaction between UCH-L1 and Jab1 in ovaries. These results suggest that UCH-L1 plays an important role, possibly in association with Jab1 and p27(Kipl), in selective elimination of abnormal oocytes during mouse prepubertal development.