The Function Of JMY In Sertoli Cell And Its Mechanism

The testicular sustentacular cells,also known as Sertoli cells,are the only somatic cells that are in contact with spermatogenic cells in the seminiferous epithelium of the testis.The complex cell junctions between Sertoli cells and Sertoli cells as well as between Sertoli cells and germ cells provide support to spermatogenesis,especially the blood testis barrier formed by Sertoli-Sertoli cell junctions in the basal part of the seminiferous epithelium.Actin and Actin-related proteins,such as Wiskott-Aldrich syndrome protein(WASP),play an important role in maintaining the integrity and stability of the blood testis barrier in Sertoli cells.Recent studies have shown that junction-mediating and regulatory protein(JMY),a member of the WASp family similar to WASP,as an Actin regulator involves not only in cell adhesion and cell migration by promoting Actin assembly,but in endocytic vesicle trafficking as well.However,there is no article that reported JMY and its relationship with male reproduction.In the previous study,we initially found that JMY protein was highly expressed in mouse testis and mainly expressed in Sertoli cells.Conditional knockout(CKO)of Jmy in the Sertoli cells was enginerred to explore the function of JMY.On the basis of this model,combined with the research of regulation mechanism of cell junction,the correlation of cell junction between JMY and Sertoli cells was further explored in order to clarify the function of JMY on spermatogenesis and male reproduction by fertility comparison,sperm quality analysis,morphological analysis,primary Sertoli cell culture,related protein detection and cytoskeleton structure comparison.Here,we found a significant decline in fertility and sperm quality of the Jmy CKO mice.Moreover,the cells arrangement of the seminiferous epithelium seemed disorder and the abscission of spermatids were found in the lumen of seminiferous epithelium.More seriously,junction structures between the Sertoli cells were greatly disrupted and the integrity of blood–testis barrier was severely impaired.Meanwhile,endocytosis related proteins(i.e.Clathrin and EEA-1)were increased expression in Jmy CKO testes while junction proteins including the tight junction proteins(i.e.Claudin11)and adherens junction proteins(i.e.β-catenin,N-cadherin)were decreased expression.The biotin labeled membranal proteins were detected at the surface of cells and transported into the cytoplasm by endocytosis,but they could not undergo further endocytic trafficking and therefore they accumulated in the cytoplasm while the signal of biotin disappeared at the cell junction.Therefore,the results of this study showed that in Sertoli cells,JMY participated in endocytic vesicle trafficking,which mediated the cell junction proteins and maintained the dynamic stability of cell junctions in order to establish the function of the blood testis barrier.The deletion of JMY did not necessarily have impact on the endocytosis of Sertoli cells,but it blocked endocytic vesicles trafficking and the formation of early endosomes,resulting in the accumulation of endocytic vesicles in the cytoplasm,which caused the endocytosed junction protein not to be recycled back to the plasma membrane,finally leading to cell junction even the BTB impairement.In conclusion,by the research in Sertoli cell specific Jmy CKO mice,we found that JMY protein plays an crucial role in regulating cell junction and maintaining the function of BTB in Sertoli cells.At the same time,it revealed JMY could interact with α-Actinin and Sorbs 2 in Sertoli cells,thereby it might be involved in actin cytoskeletal organization and endocytic vesicle trafficking.From a clinical view,this study will provide an important theoretical and reliable experimental basis for the development of a new target pill for male contraceptives,which focued on cell junction in Sertoli cells.