Controlling Cell Division’s Last Step

Before a cell divides in two, it must ensure that the daughter cell possesses correctly copied DNA as well as essential organelles and cytoplasm. Researchers have now pinpointed the protein that acts as a checkpoint before the final split can occur (Science, DOI: 10.1126/science.12171180). In addition to illuminating how the essential biological process of cell division is controlled, the discovery may also provide insights into cancer, because cell division occurs unchecked in this disease. The final physical separation of cells is orchestrated by a complex of about seven or eight proteins, says Juan Martin-Serrano of King’s College London School of Medicine. His team found that when one of the proteins (CHMP4C) in this complex becomes phosphorylated, the final separation of the two cells is stalled. Cells use this checkpoint as an opportunity to ensure chromosome segregation has taken place without error, he adds. “This is quite a surprising finding,” comments Harald Stenmark, a biochemist at Oslo University Hospital, in Norway. Researchers had thought CHMP4C was a green light forward, but it turns out that CHMP4C is actually a brake, he says.