Axin localizes to mitotic spindles and centrosomes in mitotic cells.
Wnt signaling plays critical roles in cell proliferation and carcinogenesis. In addition, numerous recent studies have shown that various Wnt signaling components are involved in mitosis and chromosomal instability. However, the role of Axin, a negative regulator of Wnt signaling, in mitosis has remained unclear. Using monoclonal antibodies against Axin, we found that Axin localizes to the centrosome and along mitotic spindles. This localization was suppressed by siRNA specific for Aurora A kinase and by Aurora kinase inhibitor. Interestingly, Axin over-expression altered the subcellular distribution of Plk1 and of phosphorylated glycogen synthase kinase (GSK3beta) without producing any notable changes in cellular phenotype. In the presence of Aurora kinase inhibitor, Axin over-expression induced the formation of cleavage furrow-like structures and of prominent astral microtubules lacking midbody formation in a subset of cells. Our results suggest that Axin modulates distribution of Axin-associated proteins such as Plk1 and GSK3beta in an expression level-dependent manner and these interactions affect the mitotic process, including cytokinesis under certain conditions, such as in the presence of Aurora kinase inhibitor.
Kim
Shi-Mun
SM
Laboratory of Cell Biology, Department of Microbiology and Bank for Pathogenic Virus, College of Medicine, Korea University, Seoul 136-705, South Korea.
Choi
Eun-Jin
EJ
Song
Ki-Joon
KJ
Kim
Sewoon
S
Seo
Eunjeong
E
Jho
Eek-Hoon
EH
Kee
Sun-Ho
SH