The Study Of GGPPS-mediated Physical Niche And Chemical Niche Regulating Spermatogenesis

Non-obstructive azoospermia(NOA)heavily affects male infertility,which is thought that sperm production is severely disturbed or even absent.However,researches to clarify the exact mechanisms of and reason for this disease are lacking.Generally,thereVe three kinds of NOA:Sertoli cell only,hypospermatosenesis and maturation arrest.The latter two kinds of NOA both show germ cell existing,which maturation arrest patients have more germ cells.Thus,understanding the mechanisms that rebooting spermatogenesis in hypospermatogesis and maturation arrest patients has important implications for the treatment of male fertility.In seminiferous tubule.Sertoli cell and germ cell are two major cell types.Sertoli cells extend their thin cytoplasm arms around all the germ cells to nurture their development and these intercellular associations are maintained throughout the process of spermatogenesis.Mature Sertoli cells form three types of intercellular junctions:cadherin-based adherens junctions,occiudin-based tight junctions and connexin-based gap junctions.These junctions are involved in forming the blood-testis barrier(BTB).In addition to BTB,the developing germ cells also interact with Sertoli cells and form a number of distinct stage-specific junctions.The BTB and cell junctions both compose the physical niche to maintain spermatogenesis.On the other hand,Sertoli cell can secrete cytokines such as GDNF,FGF2 and CxcI12 to maintain SSC niche.Also,metabolites are secreted by Sertoli cell such as lactate to support spermatogenesis.They constitute the chemical niche for the maintenance of SSC function.The physical and chemical niche are essential for spermatogenesis by providing physical and chemical support.GGPPS is a branch point enzy,e in the mevalonate pathway that catalyzes the synthesis of geranylgeranyl diphosphate(GGPP)from farnesyl diphosphate(FPP),which can be involved in prenylating signal proteins such as the Ras family.Our previous work indicated that Ggpps deletion in Sertoli cell led to male infertilitv.We also found that the expression level of GGPPS in NOA patients was lower than that in OA patients.This suggests us that GGPPS may be involved in regulation of NOA mechanism.In this study,we demonstrate that,although spermatogenesis is arrested in NOA patients,undifferentiated spermatogonialstem cells(SSCs)still exist in the basal compartment of the seminiferous tubules.The existence of these SSCs is dependent on the integrity of the BTB,which is formed by the Sertoli cells,not only conveying signals but also providing essential structure support for germ cell development.However,the BTB in NOA patients is incomplete and the adhesions between Sertoli cells and germ cells are also broken.When we knockout Ggpps specifically in Sertoli cell to mimic the characteristics of NOA,the BTB and cell adhesions in the adiuminai compartment are severely destroyed.When we treat the Sertoli cells with FPP transferase inhibitor(FTI)to decrease the farnesylation of small G-proteins,we discover that the expression of junction proteins in knockout mice are increased.These data demonstrate that the defective BTB structure and cell adhesion are associated with altered prenylation of small G-proteins after Ggpps knockout.In addition,we find that the glucose metabolic enzymes in Sertoli cell are decreased after Ggpps deletion,which may block the metabolic communication between Sertoli cell and germ cell to disturb spermatogenesis.In the context of disrupted BTB and cell adhesion,we apply berberine(BBR),which has been described to ameliorate metabolic disorders and improve intestinal barrier dysfunction,to treat the knockout mice,and find that berberine is not only able to ameliorate abnormal cell adhesions,but also able to improve the chemical niche.These evidences suggest that cell junctions between the SCs and GCs are crucial for spermatogenesis and that ameliorating the disrupted BTB could be a prospective therapeutic strategy for NOA patients.The study aims to clarify the mechanism underlie the regulation of the NOA patients.We construct a mice model and discover that the role of Ggpps in Sertoli cell is vital for spermatogenesis by influencing the physical and chemical niche.On the one hand,it regulates the BTB structure and cell junctions;on the other hand,it’s involved in maintenance of chemical niche to support gern cell development.At last,we find that berberine could reboot the spermatogenesis by not only ameliorating the disrupted BTB structure and cell junctions,but also regulating the chemical niche,which may supply a new target for NOA treatment.