Changes in Ect2 localization couple actomyosin-dependent cell shape changes to mitotic progression.
As they enter mitosis, animal cells undergo profound actin-dependent changes in shape to become round. Here we identify the Cdk1 substrate, Ect2, as a central regulator of mitotic rounding, thus uncovering a link between the cell-cycle machinery that drives mitotic entry and its accompanying actin remodeling. Ect2 is a RhoGEF that plays a well-established role in formation of the actomyosin contractile ring at mitotic exit, through the local activation of RhoA. We find that Ect2 first becomes active in prophase, when it is exported from the nucleus into the cytoplasm, activating RhoA to induce the formation of a mechanically stiff and rounded metaphase cortex. Then, at anaphase, binding to RacGAP1 at the spindle midzone repositions Ect2 to induce local actomyosin ring formation. Ect2 localization therefore defines the stage-specific changes in actin cortex organization critical for accurate cell division.
MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK.
Helen K
HK
Matthews
Ulysse
U
Delabre
Jennifer L
JL
Rohn
Jochen
J
Guck
Patricia
P
Kunda
Buzz
B
Baum
D000205:Actomyosin / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D048430:Cell Shape; D003599:Cytoskeleton / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis; D010766:Phosphorylation; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
C489850:ECT2 protein, human; D011518:Proto-Oncogene Proteins; D000205:Actomyosin; D020742:rhoA GTP-Binding Protein