The Regulation Of Rnase T2 On Sperm Motility

Ribonuclease T2 family(RNase T2) was found to exist in prokaryote and eukaryote and play an significant role in physiological activities, including scavenging of nucleic acids, modulating host immune responses and cell proliferation and motility. There are some evidences to suggest that RNase T2 is implicated as a tumor suppressor by its catalytic-independent function and the ACTIBIND,one of the ribonuclease T2 family members,can bind to actin of cancer cell and interfere with the intracellular actin network by compete with angiogenin, and finally to inhibit cancer cell growth and motility.The actin are rich in the acrosome area, neck and the tail of mammalian sperm that can play an important role in modulating sperm motility. Thus, we asked if a) there is RNase T2 presented in spermatozoa; b) RNase T2 modulates the sperm motility by interacting with actin cytoskeleton. c) RNase T2 can inhibit sperm motility, especially progressive motile.In this study, RNaseT2 expression in the reproductive system from male mouse as well as fresh spermatozoa from epididymal cauda was detected by Western blot and localized by indirect immunofluorescence analysis. We found that RNase T2 was mainly expressed in the epididymal caput, prostate and the lumen of ductus deferens. It also can be co-localized with actin in the acrosome area, neck and the middle piece of tail region. Thus, in order to determine the inhibitory effect of RNase T2 on sperm motility, especially for progressive motile, we purified RNase T2 protein from the growth medium of Aspergillus niger and the purified RNase T2 was identified by both SDS-PAGE and Western blot analyses. Therefore, the mouse spermatozoa was co-incubated with the RNase T2 protein in vitro and then the inhibitory efficiency on sperm motility and progressive motile were evaluated by a computer assisted semen analyzer(CASA). The results showed that RNase T2 could inhibit both sperm motility and progressive motile in a concentration and time dependant manners(p<0.05). On the other hand, we also identified and localized RNase T2 in healthy donor’s spermatozoa by immunofluorescence analyses. The result revealed that the RNase T2 was located in the acrosome, neck and middle piece of sperm flagellum. At the 0.1mg/ml concentration of RNase T2, the inhibitory effects of RNase T2 on both sperm motility and progressive motile were significant in a time-dependant manner.In conclusion, we found that RNase T2 has an inhibitory effect on sperm motility and progressive motile in both mouse and health donor’s spermatozoa. Definitely, it may be crucial for clarification of the molecular mechanism linked to RNase T2 function and also for pathogenesis investigation in asthenozoospermia.