Kinesin-1 Prevents Capture of the Oocyte Meiotic Spindle by the Sperm Aster

摘要

Centrioles are lost during oogenesis and inherited from the sperm at fertilization. In the zygote, the centrioles recruit pericentriolar proteins from the egg to form a mature centrosome that nucleates a sperm aster. The sperm aster then captures the female pronucleus to join the maternal and paternal genomes. Because fertilization occurs before completion of female meiosis, some mechanism must prevent capture of the meiotic spindle by the sperm aster. Here we show that in wild-type . Caenorhabditis elegans zygotes, maternal pericentriolar proteins are not recruited to the sperm centrioles until after completion of meiosis. Depletion of kinesin-1 heavy chain or its binding partner resulted in premature centrosome maturation during meiosis and growth of a sperm aster that could capture the oocyte meiotic spindle. Kinesin prevents recruitment of pericentriolar proteins by coating the sperm DNA and centrioles and thus prevents triploidy by a nonmotor mechanism. Because fertilization occurs before completion of oocyte meiosis, female meiotic spindles must be protected from interference from sperm asters. McNally et al. show that in . Caenorhabditis elegans zygotes, kinesin-1 prevents sperm aster formation by blocking recruitment of maternal pericentriolar proteins to the paternal centrioles until after completion of meiosis.