Incenp and an aurora-like kinase form a complex essential for chromosome segregation and efficient completion of cytokinesis.
BACKGROUND
In animal cells, cytokinesis begins shortly after the sister chromatids move to the spindle poles. The inner centromere protein (Incenp)has been implicated in both chromosome segregation and cytokinesis, but it is not known exactly how it mediates these two distinct processes.


RESULTS
We identified two Caenorhabditis elegans proteins, ICP-1 and ICP-2, with significant homology in their carboxyl termini to the corresponding region of vertebrate Incenp. Embryos depleted of ICP-1 by RNA-mediated interference had defects in both chromosome segregation and cytokinesis. Depletion of the Aurora-like kinase AIR-2 resulted in a similar phenotype. The carboxy-terminal region of Incenp is also homologous to that in Sli15p, a budding yeast protein that functions with the yeast Aurora kinase Ipl1p. ICP-1 bound C. elegans AIR-2 in vitro, and the corresponding mammalian orthologs Incenp and AIRK2 could be co-immunoprecipitated from cell extracts. A significant fraction of embryos depleted of ICP-1 and AIR-2 completed one cell division over the course of several cell cycles. ICP-1 promoted the stable localization of ZEN-4 (also known as CeMKLP1), a kinesin-like protein required for central spindle assembly.


CONCLUSIONS
ICP-1 and AIR-2 are part of a complex that is essential for chromosome segregation and for efficient completion of cytokinesis. We propose that this complex acts by promoting dissolution of sister chromatid cohesion and the assembly of the central spindle.
Kaitna
S
S
Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.
Mendoza
M
M
Jantsch-Plunger
V
V
Glotzer
M
M
D000595:Amino Acid Sequence; D064096:Aurora Kinase A; D064107:Aurora Kinase B; D064127:Aurora Kinases; D029742:Caenorhabditis elegans Proteins; D002453:Cell Cycle; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000378:metabolism*; D002875:Chromosomes; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D029742:Caenorhabditis elegans Proteins; D002868:Chromosomal Proteins, Non-Histone; C513185:Incenp protein, mouse; C576924:Aurkb protein, mouse; D064096:Aurora Kinase A; D064107:Aurora Kinase B; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; C576939:air-1 protein, C elegans; C491506:air-2 protein, C elegans