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31 March 2017 c-Jun N-terminal kinase and p38 mitogen-activated protein kinase pathways link capacitation with apoptosis and seminal plasma proteins protect sperm by interfering with both routes
Carolina Luna, Noelia Mendoza, Adriana Casao, Rosaura Pérez-Pé, José A. Cebrián-Pérez, Teresa Muiño-Blanco
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Abstract

The mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), and p38 MAP kinase (p38) signaling cascades are involved in triggering apoptosis in somatic cells. Given that spermatozoa are able to undergo apoptosis, we tested the hypothesis that these pathways might be functional in ram spermatozoa as two signal transduction mechanisms that contribute to the modulation of capacitation and apoptosis. Indirect immunofluorescence and western blot analysis evidenced the presence of JNK and p38 in ram spermatozoa. To verify the involvement of these enzymes in sperm physiology, we determined the effect of specific inhibitors of JNK or p38 on in vitro capacitation induced with either cAMP-elevating agents or epidermal growth factor (EGF). Both inhibitions reduced the EGF-induced capacitation with a decrease in the chlortetracycline capacitated-sperm pattern, protein tyrosine phosphorylation, phosphatidylserine externalization, caspase-3 and -7 activation, and the proportion of DNA-damaged spermatozoa. No significant changes were found in the high-cAMP capacitated samples. The addition of 3.4 mg/ml seminal plasma proteins (SPPs) to the EGF-containing samples, either alone or together with each inhibitor, resulted in a decreased proportion of capacitated sperm pattern, protein tyrosine phosphorylation, loss of plasma membrane integrity, and apoptotic alterations. Furthermore, SPPs significantly reduced the phosphorylation level of JNK and p38 MAPK (active forms). These findings show a relationship between capacitation and apoptosis, and represent a step forward in the knowledge of the SPP protective mechanism in spermatozoa.

JNK and p38 MAPKs are activated during in vitro ram sperm capacitation with EGF, and seminal plasma proteins protect sperm not only acting at the plasma level but also by interfering with both MAPK pathways.

© The Authors 2017. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please journals.permissions@oup.com
Carolina Luna, Noelia Mendoza, Adriana Casao, Rosaura Pérez-Pé, José A. Cebrián-Pérez, and Teresa Muiño-Blanco "c-Jun N-terminal kinase and p38 mitogen-activated protein kinase pathways link capacitation with apoptosis and seminal plasma proteins protect sperm by interfering with both routes," Biology of Reproduction 96(4), 800-815, (31 March 2017). https://doi.org/10.1093/biolre/iox017
Received: 24 March 2017; Accepted: 28 March 2017; Published: 31 March 2017
JOURNAL ARTICLE
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