INVESTIGADORES
KUNDA Patricia Elena
congresos y reuniones científicas
Título:
PP1-87B phosphatase comtrols mitosis by regulating the phosphorylation state of Moesin adn cortical rigidity
Autor/es:
KUNDA, PATRICIA; RODRIGUES, NELIO; MOEENDARBARY, EMADALDIN; BAUM, BUZZ
Reunión:
Conferencia; 4to European Cell Mechanics Meeting; 2011
Resumen:
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Animal cells retract
their margin and round up at the onset of mitosis. We have shown that mitotic
cell rounding is regulated by active Moesin, a member of the ERM family, in Drosophila
cells. Moesin is activated by Slik-dependent phosphorylation at the onset of
mitosis. It localizes uniformly tothe mitotic cell cortex where it is required
to establish a stiff cortex that acts as a mechanical support for spindle
assembly and orderly chromosome segregation.
Here we report that de-phosphorylation of Moesin
is important for the timely disassembly of the rigid cell cortex at anaphase.
By using RNAi screening in Drosophila cell lines, we have identified
PP187B, a type I serine/threonine phosphatase, that is responsible for
mitotic Moesin dephosphorylation. PP1 RNAi treated Drosophila
cells are smaller and rounder than control cells and, as expected for a
negative regulator of Moesin, exhibit a significant increase in cortical
stiffness. Furthermore, in mitosis in cell culture and in vivo in the
fly notum, PP1 suppression by RNAi leads to an increase in phospho-Moesin levels
and, more strikingly, to a delay in cell elongation prior to cytokinesis.
Moreover, mitotic spindles have a collapsed appearance in cells in which PP1 is
suppressed by RNAi, which is rescued by addition of latrunculin. This suggests
that coordination of the events of ERM protein phosphorylation upon entry into
mitosis with dephosphorylation at mitotic exit
is important to generate the appropriate mechanical features of cells
required for cell division.
