Disruption of ectoplasmic specializations between Sertoli cells and maturing spermatids by anti-nectin-2 and anti-nectin-3 antibodies

Aim： To understand the biological functions of the ectoplasmic specializations between Sertoli cells and maturing spermatids in seminiferous epithelia. Methods： In order to disrupt the function of the ectoplasmic specializations, nectin-2, which is expressed at the specialization, was neutralized with anti-nectin-2 antibody micro-injected into the lumen of the mouse seminiferous tubule. Anti-nectin-3 antibody was also micro-injected into the lumen in order to neutralize nectin-3, which is expressed at the specialization. Results： The actin filaments at the specialization disappeared, and exfoliation of maturing spermatids was observed by electron microscopy. Conclusion： Nectin-2 was neutralized by anti-nectin-2 antibody and nectin-3 was neutralized by anti-nectin-3 antibody, respectively. Inactivated nectin-2 and nectin-3 disrupted the nectin-afadin-actin system, and finally the actin filaments disappeared. As a result, the specialization lost the holding function and detachment of spermatids was observed. One of the functions of the specialization seems to be to hold maturing spermatids until spermiation.

Establishment of an oligoasthenospermia mouse model based on TAp73 gene suppression

Background:Oligoasthenospermia is one of the main causes of male infertility.Researchers usually use chemical drugs to directly damage germ cells to prepare oligoasthenospermia models,which disregards the adhesion and migration between spermatogenic cells and Sertoli cells.TAp73 is a critical regulator of the adhesin of germ cell;thus,we sought to explore a novel oligoasthenospermia model based on TAp73 gene suppression.Methods:Mice in the Pifithrin-αgroup were injected intraperitoneally with 2.5 mg/kg Pifithrin-α(TAp73 inhibitor)daily for 30 consecutive days.Reproductive hormone levels and epididymal sperm quality,as well as the network morphology of Sertoli cells were tested.Results:Sperm density,motility,and the relative protein and mRNA expression of TAp73 and Nectin 2 were obviously decreased in the Pifithrin-αgroup compared with the normal control group.No significant distinction was observed in the relative mRNA and protein expression of ZO-1.Furthermore,the tight junctions(TJs)and api-cal ectoplasmic specialization(ES)were destroyed in the Pifithrin-αgroup.Conclusion:The above results indicate that we successfully established a new oli-goasthenospermia mouse model.This study provides a foundation for further explo-ration of the roles of TAp73 genes during spermatogenesis and provides new research objects for further oligospermia research and future drug discovery.

Ezrin： a regulator of actin microfilaments in ce unctions of the rat testis

Ezrin, radixin, moesin and merlin （ERM） proteins are highly homologous actin-binding proteins that share extensive sequence similarity with each other. These proteins tether integral membrane proteins and their cytoplasmic peripheral proteins （e.g., adaptors, nonreceptor protein kinases and phosphatases） to the microfilaments of actin-based cytoskeleton. Thus, these proteins are crucial to confer integrity of the apical membrane domain and its associated junctional complex, namely the tight junction and the adherens junction. Since ectoplasmic specialization （ES） is an F-actin-rich testis-specific anchoring junction-a highly dynamic ultrastructure in the seminiferous epithelium due to continuous transport of germ cells, in particular spermatids, across the epithelium during the epithelial cycle-it is conceivable that ERM proteins are playing an active role in these events. Although these proteins were first reported almost 25 years and have since been extensively studied in multiple epithelia/endothelia, few reports are found in the literature to examine their role in the actin filament bundles at the ES. Studies have shown that ezrin is also a constituent protein of the actin-based tunneling nanotubes （TNT） also known as intercellular bridges, which are transient cytoplasmic tubular ultrastructures that transport signals, molecules and even organelles between adjacent and distant cells in an epithelium to coordinate cell events that occur across an epithelium. Herein, we critically evaluate recent data on ERM in light of recent findings in the field in particular ezrin regarding its role in actin dynamics at the ES in the testis, illustrating additional studies are warranted to examine its physiological significance in spermatogenesis.