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| 7: Mol Hum Reprod. 2003 Mar;9(3):125-31. |
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- Role of protein tyrosine phosphorylation in the
thapsigargin-induced intracellular Ca(2+) store depletion during human sperm
acrosome reaction.
Dorval V, Dufour M, Leclerc P.
Departement d'Obstetrique/Gynecologie and Centre de recherche en Biologie de
la Reproduction, Universite Laval, and Centre de recherche du CHUQ, Quebec,
G1L 3L5 and.
During human sperm capacitation, an increase in phosphotyrosine content of
specific proteins results partially from an increase in the intracellular free
Ca(2+) concentrations. In the present study, the inter-regulation between
protein phosphotyrosine content and the intracellular Ca(2+) concentration
during the thapsigargin treatment of capacitated human sperm was investigated.
The involvement of a tyrosine kinase pathway in the thapsigargin-induced
acrosome reaction was also investigated. In response to thapsigargin, two
sperm subpopulations, called LR (low responsive) and HR (high responsive),
according to their increase in intracellular Ca(2+), were observed. In
addition to their high increase in intracellular Ca(2+), sperm from the HR
population expressed a higher protein phosphotyrosine content, and a higher
proportion (P < 0.05) of them underwent the acrosome reaction in response to
thapsigargin, as compared with LR sperm. Although the tyrosine kinase
inhibitor PP2 abolished the thapsigargin-induced increase in protein
phosphotyrosine content, it did not affect the intracellular Ca( 2+)
concentration or the percentage of acrosome-reacted sperm. The inability of an
src-related tyrosine kinase inhibitor to block the thapsigargin-mediated
Ca(2+) increase and acrosomal exocytosis suggests that, during the acrosome
reaction, the signalling pathway mediated by src-related tyrosine kinases is
involved upstream of the capacitative Ca(2+) entry.
PMID: 12606588 [PubMed - in process]
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