Seshagiri, PB and Thomas, M and Sreekumar, A and Ray, P and Mariappa, D (2003) Pentoxifylline induced signalling events during capacitation of hamster spermatozoa: Significance of protein tyrosine phosphorylation. In: Cellular And Molecular Biology, 49 (3). pp. 371-380.
Full text not available from this repository. (Request a copy)Abstract
To fertilize the oocyte, mammalian spermatozoa must undergo capacitation and acrosome reaction. These events are believed to be associated with various biochemical changes primarily mediated by cAMP, Ca2+ and protein kinases. But the precise signaling mechanisms governing sperm function are not clear. To study this, we used pentoxifylline (PF), a sperm motility stimulant and a cAMP-phosphodiesterase inhibitor, during capacitation and acrosome reaction of hamster spermatozoa. PF induced an early onset of sperin capacitation and its action involved modulation of sperm cell signaling molecules viz., cAMP, [Ca2+](i) and protein kinases. The PF-induced capacitation was associated with an early and increased total protein phosphorylation coupled with changes in the levels of reactive oxygen species. Protein kinase (PK)-A inhibitor (H-89) completely inhibited phosphorylation of a 29 kDa protein while PK-C inhibitor (staurosporine) did not inhibit phosphorylation. Interestingly, PF induced protein tyrosine phosphorylation of a set of proteins (M-r 45-80 K) and a greater proportion of PF-treated spermatozoa exhibited protein tyrosine phosphorylation, compared to untreated controls (82 + 9% vs 34 +/- 10%; p<0.001); tyrosine-phosphorylated proteins were localized specifically to the mid-piece of the sperm. The profile of protein tyrosine phosphorylation was inhibitable by higher concentrations (>0.5 mM) of tyrosine kinase inhibitor, tyrphostin A47. However, at lower (0.1-0.25 mM) concentrations, the compound interestingly induced early sperm capacitation and protein tyrosine phosphorylation, like PF. These results show that protein tyrosine phosphorylation in the mid-piece segment (mitochondrial sheath) appears to be an early and essential event during PF-induced capacitation and a regulated level of tyrosine phosphorylation of sperm proteins is critical for capacitation of hamster spermatozoa.
| Item Type: | Journal Article |
|---|---|
| Publication: | Cellular And Molecular Biology |
| Publisher: | Cellular And Molecular Biology |
| Additional Information: | Copyright of this article belongs to Cellular And Molecular Biology. |
| Keywords: | spermatozoa (hamster);pentoxifylline;tyrosine phosphorylation;capacitation. |
| Department/Centre: | Division of Biological Sciences > Molecular Reproduction, Development & Genetics |
| Date Deposited: | 24 Nov 2009 10:13 |
| Last Modified: | 24 Nov 2009 10:13 |
| URI: | http://eprints.iisc.ac.in/id/eprint/17250 |
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