PTEN in the middle of the cell (top) and PI3 kinase at the poles (bottom) help drive cytokinesis.
DEVREOTES/ELSEVIER
A dividing cell mimics two half cells migrating away from each other, according to Chris Janetopoulos, Peter Devreotes, and colleagues (Johns Hopkins University, Baltimore, MD). A gradient of PI(3,4,5)P
3 appears to help the two ends of the cell to expand outwards, even as the middle of the cell favors contraction.Devreotes has long studied PI(3,4,5)P
3 involvement in
Dictyostelium migration, where signaling through chemotaxis receptors leads to PI(3,4,5)P
3 accumulation at the front of the cell. The excess PI(3,4,5)P
3 supports actin-led forward propulsion, whereas low PI(3,4,5)P
3 at the rear of the cell results in contraction. This situation is maintained by membrane localization of PI kinases at the front of the cell and of the PIP phosphatase PTEN at the rear.
