Role And Mechanism Of Gsk3? In Heat Stress-Induced Impairment Of Testicular Sertoli Cell Metabolism And Sperm Motility

Spermatogenesis and semen quality of male are an important affecting factor of reproduction efficiency.In the process of spermatogenesis,sertoli cells mainly functions are provide the necessary nutrients for the development of the germ cells and phagocytosis of apoptotic germ cells.Glycogen synthase kinase 3a(GSK3a)is participate in regulation of mitochondrial function.Studies have showed that GSK3a is also involved in regulation of sperm motility.However,in the state of heat stress,role of GSK3a in spennatogenesis and regulation of sperm motility are not clear.In this study,role and mechanism of GSK3a in heat stress induced impairment of testicular sertoli cell metabolism and sperm motility were investigated.1 Role and mechanism of GSK3a in the effects of heat stress on testicular sertoli cell phagocytosis and metabolismIn this study,male adult mice were exposed to 42? heat stress as the model.The results showed that p-GSK3a(Ser21)is mainly distributed in testicular sertoli cells,and heat stress resulted in a significant decrease in the level of phosphorylation of the GSK3a(Ser21)in the testicular sertoli cells.It is worth noting that tail vein injection GSK3a inhibitor SB216763 can reduce the apoptosis of testicular germ cells by heat stress.In vitro.TM4 cell line used as the model,results showed that heat stress-induced phagocytosis significantly decreased of TM4 cell,GSK3? inhibitor can relieve that heat stress-induced phagocytosis downregulation of TM4 cell.Heat stress-induced TM4 cell mitochondrial dysfunction that is indicated through decreased of MMP,increased in the level of phosphorylation of the Drpl.The decreased of phagocytosis in HS-treated Sertoli cells,whereas GSK3a inhibitor supplementation restored the level of phagocytosis.GSK3a activation inhibits in mitochondrial fission via phosphorylation of Drpl at Ser637.Besides,heat stress-induced increased of TG,lactic acid content and lipid droplets accumulation.In summary,in the case of heat stress,GSK3a is involved in the regulation of TM4 cell phagocytosis and metabolism,which is related with mitochondrial dysfunction.The results demonstrate that Inactivation of GSK3a is required for mitochondria-mediated apoptotic germ cell phagocytosis in Sertoli cell.2 Role and mechanism of GSK3a in the effect of heat stress on sperm mitochondrial function and motilityPrevious studies indicated that GSK3a Ser21 phosphorylation was involved in the regulation of mitochondrial activity,the effect of heat stress on sperm motility may be related to the regulation of mitochondrial function and ATP synthesis by GSK3a.To test this hypothesis,we used mature boar sperm as model to explore the impacts of heat stress on mitochondrial function and sperm motility.A 6 h exposure to heat stress induced significant decrease in sperm progressive motility.Concurrently,heat stress induced mitochondrial dysfunction that is indicated by decreased of MMP,respiratory chain complex I and IV activities and ATP contents.Exogenous ATP abolished this effect suggesting that reduced of ATP synthesis is the committed step in heat stress induced reduction of sperm motility.At the molecular level,the mitochondrial protein contents were significantly decreased in heat-stressed sperm.Notably,the cytochrome c oxidase subunit 4(COX4),which was synthesized in cytoplasm and translocated into mitochondria,was significantly lower in mitochondria of heat-stressed sperm.Heat stress resulted in a significant decrease in the level of phosphorylation of the GSK3a(Ser21).The GSK3a inhibitor CHIR99021 was able to abolish the effects of heat stress on sperm and their mitochondria-Taken together,our results demonstrate that heat stress affects sperm motility through downregulation of mitochondrial activity and ATP synthesis,which involves dephosphorylation of GSK3a and interference of mitochondrial function.