Journal of Cell Science 116, e405-e405 (2003)
Copyright © 2003 The Company of Biologists Limited
GSK-3 and spindle dynamics
Glycogen synthase kinase 3 (GSK-3) is a ubiquitously expressed enzyme that
is constitutively active in resting cells and phosphorylates a wide variety of
proteins — from glycogen synthase to microtubule-associated proteins.
During insulin signalling, the kinase PDK1 phosphorylates and activates
protein kinase B (PKB), which in turn phosphorylates and inactivates
GSK-3. James Wakefield and co-workers now show that a similar pathway controls
spindle dynamics at mitosis (see p.
637). They find that GSK-3 is present along spindle microtubules. In
addition, they demonstrate that the phosphorylated form is concentrated at
spindle poles and centrosomes. where phosphorylated, active PKB is also
present. Using two distinct GSK-3 inhibitors, the authors show that inhibition
of GSK-3 leads to an increase in the length of spindle microtubules and
defective chromosome alignment at prometaphase. Furthermore, live microscopy
reveals that this reduces chromosome movement and produces a prometaphase
arrest. Wakefield and co-workers conclude that spatiotemporal control of GSK-3
activity is important for control of microtubule dynamics at mitosis. It could
ensure stabilization of microtubules at centrosomes but allow them to remain
dynamic elsewhere and thus scour the cytoplasm for chromosomes.
Related articles in JCS:
- A role for glycogen synthase kinase-3 in mitotic spindle dynamics and chromosome alignment
- James G. Wakefield, David J. Stephens, and Jeremy M. Tavaré
JCS 2003 116: 637-646.
[Abstract]
[Full Text]
