Membrane modifications in sperm cells represent a key step in sperm capacitation; however, the molecular basis of these modifications is not fully understood. Ezrin is the best-studied member of the ezrin/radixin/merl...Membrane modifications in sperm cells represent a key step in sperm capacitation; however, the molecular basis of these modifications is not fully understood. Ezrin is the best-studied member of the ezrin/radixin/merlin family. As a cross-linker between the cortical cytoskeleton and plasma membrane proteins, ezrin contributes to remodeling of the membrane surface structure. Furthermore, activated ezrin and the Rho dissociation inhibitor, RhoGDI, promote the formation of cortical cytoskeleton-polymerized actin through Rho activation. Thus, ezrin, actin, RhoGDI, Rho and plasma membrane proteins form a complicated network in vivo, which contributes to the assembly of the structure of the membrane surface. Previously, we showed that ezrin and RhoGDI1 are expressed in human testes. Thus, we sought to determine whether the ezrin-RhoGDIl-actin-membrane protein network has a role in human sperm capacitation. Our results by Western blot indicate that ezrin is activated by phosphorylation of the threonine567 residue during capacitation. Co-immunoprecipitation studies revealed that, during sperm capacitation, the interaction between ezrin and RhoGDI1 increases, and phosphostaining of two dimensional electrophoresis gels showed that RhoGDI 1 is phosphorylated, suggesting that RhoGDI 1 dissociates from RhoA and leads to actin polymerization on the sperm head. We speculate that activated ezrin interacts with polymerized actin and the glycosylated membrane protein cd44 after capacitation. Blocking sperm capacitation using ezrin- or actin-specific monoclonal antibodies decreases their acrosome reaction （AR） rate, but has no effect on the AR alone. Taken together, our results show that a network consisting of ezrin, RhoGDI1, RhoA, F-actin and membrane proteins functions to influence the modifications that occur on the membrane of the sperm head during human sperm capacitation.展开更多
Background:Capacitation is a set of physiological changes sperms undergo to acquire fertilizing capacity.In vivo,this process is directly associated with high calcium levels in sperm cytoplasm.Calcitriol,the vitamin D...Background:Capacitation is a set of physiological changes sperms undergo to acquire fertilizing capacity.In vivo,this process is directly associated with high calcium levels in sperm cytoplasm.Calcitriol,the vitamin D hypercalcemic metabolite,is related to human sperm motility,capacitation,and acrosome reaction.This work aimed to study the effect of calcitriol on bull sperm quality parameters and capacitation.Methods:One million freezethawed spermatozoa were obtained from different bulls and treated with 20 nM of calcitriol for 30 min.Untreated cells(negative control)and treated ones with calcitriol or heparin(100μg/mL,positive capacitation control)were evaluated for motility,viability,and functional parameters.Menadione(70μM,30 min)treatment was included as a reactive oxygen species(ROS)positive sperm agent.Results:The results elucidated that sperm exposed to 20 nM calcitriol showed higher viability,vigor,and capacitation than their positive and negative controls.The percentage of sperm with intact plasma and acrosome membranes,mitochondrial membrane potential(ΔΨm),and phosphatidylserine externalization was similar in all the conditions evaluated,while ROS production was higher with heparin and menadione-treated groups than the calcitriol group or negative control.Conclusion:Our results indicate that calcitriol induces the capacitation of thawed bull spermatozoa and maintains acceptable values of progressive motility,viability,and vigor without altering key biological parameters such as redox status,ΔΨm,and cell death.展开更多
Mammalian fertilization is a highly regulated process, much of which are not clearly understood. Here we presentsome information in order to elaborate a working hypothesis for this process, beginning with the sperm mo...Mammalian fertilization is a highly regulated process, much of which are not clearly understood. Here we presentsome information in order to elaborate a working hypothesis for this process, beginning with the sperm modifications inthe epidydimis up to sperm and egg plasmalemma interaction and fusion. We also discuss the still poorly understood ca-pacitation process, the phenomenon of sperm chemo-attraction that brings the capacitated sperm to interact with theoocyte vestments and certain aspects of the acrosome reaction. (Asian J Androl 2001 Dec; 3 : 243 - 249)展开更多
A cascade of dramatic physiological events is linked to the sperm acrosome reaction and binding to the oocyte's zona pellucida during human sperm capacitation.However,structural and functional sperm changes during...A cascade of dramatic physiological events is linked to the sperm acrosome reaction and binding to the oocyte's zona pellucida during human sperm capacitation.However,structural and functional sperm changes during capacitation currently remain poorly defined.Here,we performed a multibiomarker approach based on the utilization of sperm concentration,motility,viability,morphology,acrosome reaction,tyrosine phosphorylation,DNA fragmentation,and lectin-binding sites to analyze the impact caused by swim-up selection times(uncapacitated,1 h capacitated,and 4 h capacitated)on sperm function and structure in normozoospermic samples.We found that a 4 h swim-up capacitation increased sperm quality,because a large number of cells with normal morphology and lower DNA fragmentation rates were recovered.Furthermore,the long-term capacitation induced a higher percentage of cells with tyrosine phosphorylation of the principal piece as well as a redistribution of lectin-binding sites.Overall,the multivariate biomarkers analyzed showed a less variable distribution on spermatozoa recovered after 4 h capacitation than that with the shorter capacitation time.These findings stress the importance of capacitation time as a relevant factor in sperm quality with potential biological reproductive implications both for basic research and in assisted reproduction techniques.展开更多
基金Acknowledgment This work was supported by grants from the 973 program （No. 2006CB504002）, the National Natural Science Foundation of China （No. 30630030）, the Program for the Scholars of Changjiang and the Innovative Research Team of the University （PCSIRT） （No. IRT0631） and the Jiangsu Youth Technological Innovation Projects Foundation （No. BK2007602）.
文摘Membrane modifications in sperm cells represent a key step in sperm capacitation; however, the molecular basis of these modifications is not fully understood. Ezrin is the best-studied member of the ezrin/radixin/merlin family. As a cross-linker between the cortical cytoskeleton and plasma membrane proteins, ezrin contributes to remodeling of the membrane surface structure. Furthermore, activated ezrin and the Rho dissociation inhibitor, RhoGDI, promote the formation of cortical cytoskeleton-polymerized actin through Rho activation. Thus, ezrin, actin, RhoGDI, Rho and plasma membrane proteins form a complicated network in vivo, which contributes to the assembly of the structure of the membrane surface. Previously, we showed that ezrin and RhoGDI1 are expressed in human testes. Thus, we sought to determine whether the ezrin-RhoGDIl-actin-membrane protein network has a role in human sperm capacitation. Our results by Western blot indicate that ezrin is activated by phosphorylation of the threonine567 residue during capacitation. Co-immunoprecipitation studies revealed that, during sperm capacitation, the interaction between ezrin and RhoGDI1 increases, and phosphostaining of two dimensional electrophoresis gels showed that RhoGDI 1 is phosphorylated, suggesting that RhoGDI 1 dissociates from RhoA and leads to actin polymerization on the sperm head. We speculate that activated ezrin interacts with polymerized actin and the glycosylated membrane protein cd44 after capacitation. Blocking sperm capacitation using ezrin- or actin-specific monoclonal antibodies decreases their acrosome reaction （AR） rate, but has no effect on the AR alone. Taken together, our results show that a network consisting of ezrin, RhoGDI1, RhoA, F-actin and membrane proteins functions to influence the modifications that occur on the membrane of the sperm head during human sperm capacitation.
基金Research was funded by grants from National University of Río Cuarto(UNRC)through the Secretary of Science and Technology(SECYT,PPI 2020-2022,Res 083).
文摘Background:Capacitation is a set of physiological changes sperms undergo to acquire fertilizing capacity.In vivo,this process is directly associated with high calcium levels in sperm cytoplasm.Calcitriol,the vitamin D hypercalcemic metabolite,is related to human sperm motility,capacitation,and acrosome reaction.This work aimed to study the effect of calcitriol on bull sperm quality parameters and capacitation.Methods:One million freezethawed spermatozoa were obtained from different bulls and treated with 20 nM of calcitriol for 30 min.Untreated cells(negative control)and treated ones with calcitriol or heparin(100μg/mL,positive capacitation control)were evaluated for motility,viability,and functional parameters.Menadione(70μM,30 min)treatment was included as a reactive oxygen species(ROS)positive sperm agent.Results:The results elucidated that sperm exposed to 20 nM calcitriol showed higher viability,vigor,and capacitation than their positive and negative controls.The percentage of sperm with intact plasma and acrosome membranes,mitochondrial membrane potential(ΔΨm),and phosphatidylserine externalization was similar in all the conditions evaluated,while ROS production was higher with heparin and menadione-treated groups than the calcitriol group or negative control.Conclusion:Our results indicate that calcitriol induces the capacitation of thawed bull spermatozoa and maintains acceptable values of progressive motility,viability,and vigor without altering key biological parameters such as redox status,ΔΨm,and cell death.
文摘Mammalian fertilization is a highly regulated process, much of which are not clearly understood. Here we presentsome information in order to elaborate a working hypothesis for this process, beginning with the sperm modifications inthe epidydimis up to sperm and egg plasmalemma interaction and fusion. We also discuss the still poorly understood ca-pacitation process, the phenomenon of sperm chemo-attraction that brings the capacitated sperm to interact with theoocyte vestments and certain aspects of the acrosome reaction. (Asian J Androl 2001 Dec; 3 : 243 - 249)
基金the Human Fertility Chair,the Department of Biotechnology of the University of Alicante(VIGROB-186)the project of the Spanish Ministry of Economy and Competitiveness(AGL2015-70159-P).
文摘A cascade of dramatic physiological events is linked to the sperm acrosome reaction and binding to the oocyte's zona pellucida during human sperm capacitation.However,structural and functional sperm changes during capacitation currently remain poorly defined.Here,we performed a multibiomarker approach based on the utilization of sperm concentration,motility,viability,morphology,acrosome reaction,tyrosine phosphorylation,DNA fragmentation,and lectin-binding sites to analyze the impact caused by swim-up selection times(uncapacitated,1 h capacitated,and 4 h capacitated)on sperm function and structure in normozoospermic samples.We found that a 4 h swim-up capacitation increased sperm quality,because a large number of cells with normal morphology and lower DNA fragmentation rates were recovered.Furthermore,the long-term capacitation induced a higher percentage of cells with tyrosine phosphorylation of the principal piece as well as a redistribution of lectin-binding sites.Overall,the multivariate biomarkers analyzed showed a less variable distribution on spermatozoa recovered after 4 h capacitation than that with the shorter capacitation time.These findings stress the importance of capacitation time as a relevant factor in sperm quality with potential biological reproductive implications both for basic research and in assisted reproduction techniques.
