BACKGROUND: Protein tyrosine phosphorylation is one of the main processes associated with sperm activation. Although this process and its targets have been well characterized, only few tyrosine kinases have been identified so far and their roles in spermatozoa are still largely unknown. In this study, we report the presence and localization of Src kinase in ejaculated human spermatozoa and investigate its role in regulating the processes underlying sperm activation. METHODS AND RESULTS: Specific anti-Src antibodies, against different epitopes of the protein, identified a single band of 70 kDa relating to a protein which is mainly localized in the post-acrosomal region of the head, neck and midpiece. By immunoprecipitation and immunofluorescence techniques performed with antibodies against Src phosphorylated at Tyr416, which identifies the active kinase, we showed an increased phosphorylation during sperm capacitation. Blocking Src activity with SU6656 resulted in a significant reduction in the protein tyrosine phosphorylation. Moreover, this inhibitor also blocked the progesterone-induced acrosome reaction and interfered with the calcium response to progesterone evaluated in fura-2-loaded spermatozoa. No effect on sperm motility and hyperactivation resulted from incubation with SU6656. CONCLUSIONS: We identified a novel Src isoform in human spermatozoa, which appears to be involved in regulating sperm capacitation, calcium fluxes, tyrosine phosphorylation and acrosome reaction.

Src activation triggers capacitation and acrosome reaction but not motility in human spermatozoa / G. Varano; A. Lombardi; G. Cantini; G. Forti; E. Baldi; M. Luconi.. - In: HUMAN REPRODUCTION. - ISSN 0268-1161. - STAMPA. - 23:(2008), pp. 2652-2662. [10.1093/humrep/den314]

Src activation triggers capacitation and acrosome reaction but not motility in human spermatozoa.

CANTINI, GIULIA;FORTI, GIANNI;BALDI, ELISABETTA;LUCONI, MICHAELA
2008

Abstract

BACKGROUND: Protein tyrosine phosphorylation is one of the main processes associated with sperm activation. Although this process and its targets have been well characterized, only few tyrosine kinases have been identified so far and their roles in spermatozoa are still largely unknown. In this study, we report the presence and localization of Src kinase in ejaculated human spermatozoa and investigate its role in regulating the processes underlying sperm activation. METHODS AND RESULTS: Specific anti-Src antibodies, against different epitopes of the protein, identified a single band of 70 kDa relating to a protein which is mainly localized in the post-acrosomal region of the head, neck and midpiece. By immunoprecipitation and immunofluorescence techniques performed with antibodies against Src phosphorylated at Tyr416, which identifies the active kinase, we showed an increased phosphorylation during sperm capacitation. Blocking Src activity with SU6656 resulted in a significant reduction in the protein tyrosine phosphorylation. Moreover, this inhibitor also blocked the progesterone-induced acrosome reaction and interfered with the calcium response to progesterone evaluated in fura-2-loaded spermatozoa. No effect on sperm motility and hyperactivation resulted from incubation with SU6656. CONCLUSIONS: We identified a novel Src isoform in human spermatozoa, which appears to be involved in regulating sperm capacitation, calcium fluxes, tyrosine phosphorylation and acrosome reaction.
2008
23
2652
2662
G. Varano; A. Lombardi; G. Cantini; G. Forti; E. Baldi; M. Luconi.
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/337936
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