A team at Fred Hutchinson Cancer Research Center has solved an 88-year-old mystery: how cells shield a specific segment of DNA so that sex cells — eggs or sperm in humans — end up with the right number of chromosomes.
Published Thursday in Molecular Cell, the work, done in fission yeast, reveals that a certain protein acts a like a traffic cop. This traffic-cop protein shields a key region of DNA from the wrong molecules while ushering the right ones over. The findings shed light on what may have gone awry when cells end up with too many or too few chromosomes, which can lead to spontaneous miscarriage or certain developmental disorders.
Swi6, the protein in question, “is a key regulator,” said senior author Dr. Gerald Smith, who worked with first author Dr. Mridula Nambiar to outline Swi6’s dual roles in proper chromosome sorting. “Mridula’s critical insight was that it has both positive and negative roles.”