Mammalian sperm translate nuclear-encoded proteins by mitochondrial-type ribosomes
Abstract
It is widely accepted that spermatozoa are translationally silent. The present study demonstrates, for the first time, incorporation of labeled amino acids into polypeptides during sperm capacitation, which was completely inhibited by mitochondrial translation inhibitors but not by the cytoplasmic translation inhibitor. Unlike 80S cytoplasmic ribosomes, 55S mitochondrial ribosomes were present in polysomal fractions, indicating that these ribosomes are actively involved in protein translation in spermatozoa. Inhibition of protein translation significantly reduced sperm motility, capacitation and in vitro fertilization rate. Thus, contrary to the accepted dogma, nuclear genes are expressed as proteins in sperm during their residence in the female reproductive tract until fertilization.
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Footnotes
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Supplemental material is available at http://genesdev.org.
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Article published online ahead of print. Article and publication date are at http://www.genesdev.org/cgi/doi/10.1101/gad.367606.
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↵1 Corresponding author.
↵1 E-MAIL breith{at}mail.biu.ac.il; FAX 972-3-5344766.
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- Accepted December 19, 2005.
- Received September 20, 2005.
- Cold Spring Harbor Laboratory Press
