Drosophila Aurora B Kinase Is Required for Histone H3 Phosphorylation and Condensin Recruitment during Chromosome Condensation and to Organize the Central Spindle during Cytokinesis

Abstract

Aurora/Ipl1-related kinases are a conserved family of enzymes that have multiple functions during mitotic progression. Although it has been possible to use conventional genetic analysis to dissect the function of aurora, the founding family member in Drosophila (Glover, D.M., M.H. Leibowitz, D.A. McLean, and H. Parry. 1995. Cell. 81:95–105), the lack of mutations in a second aurora-like kinase gene, aurora B, precluded this approach. We now show that depleting Aurora B kinase using double-stranded RNA interference in cultured Drosophila cells results in polyploidy. aurora B encodes a passenger protein that associates first with condensing chromatin, concentrates at centromeres, and then relocates onto the central spindle at anaphase. Cells depleted of the Aurora B kinase show only partial chromosome condensation at mitosis. This is associated with a reduction in levels of the serine 10 phosphorylated form of histone H3 and a failure to recruit the Barren condensin protein onto chromosomes. These defects are associated with abnormal segregation resulting from lagging chromatids and extensive chromatin bridging at anaphase, similar to the phenotype of barren mutants (Bhat, M.A., A.V. Philp, D.M. Glover, and H.J. Bellen. 1996. Cell. 87:1103–1114.). The majority of treated cells also fail to undertake cytokinesis and show a reduced density of microtubules in the central region of the spindle. This is accompanied by a failure to correctly localize the Pavarotti kinesin-like protein, essential for this process. We discuss these conserved functions of Aurora B kinase in chromosome transmission and cytokinesis.

Histone Hyperacetylation in Mitosis Prevents Sister Chromatid Separation and Produces Chromosome Segregation Defects

“…This indicates that association of condensation factors on chromatin is dependent on a favorable chromatin structure, which requires both Lys 9 deacetylation and Ser 10 phosphorylation. In line with this idea is the observation that Aurora B-depleted Drosophila cultured cells show altered chromosome condensation and defective association of the condensin Barren protein together with reduced H3 phosphorylation (Giet and Glover, 2001). The impaired association of HP1 protein to the centromeric region observed in Ptk1 and human cells after TSA treatment (Figure 7) demonstrates that centromeric chromatin structure is also altered when histones are maintained acetylated in mitosis.…”

“…The presence of this modified histone has been correlated with mitotic chromosome condensation in several eukaryotic systems (Hendzel et al, 1997;Wei et al, 1998). H3 phosphorylation at Ser10 is governed by the activity of aurora/Ipl1 kinases (Speliotes et al, 2000;Giet and Glover 2001;Crosio et al, 2002) in competition with the phosphatase activity of the serine/threonine protein phosphatase 1 (Hsu et al, 2000;Murnion et al, 2001). It has been shown that Ser 10-modified histone colo-calizes with the human condensin complex during G2/ prophase (Schmiesing et al, 2000), suggesting that this modification may have a role in destabilizing local chromatin structure to allow access of condensation factors to DNA or in recruiting the condensation machinery on the modified histone amino-terminal tail (Wei et al, 1998;Schmiesing et al, 2000).…”

Contractile Ring-independent Localization of DdINCENP, a Protein Important for Spindle Stability and Cytokinesis

“…They have important functions in such diverse aspect of mitosis as chromosome condensation, metaphase chromosome congression, kinetochore bipolar spindle attachment, proper chromosome segregation and checkpoint control Kim et al, 1999;Giet and Glover, 2001;Cheeseman et al, 2002;Tanaka et al, 2002;Gassmann et al, 2004;Sampath et al, 2004). Additionally, chromosomal-passenger proteins also play a prominent role during cytokinesis (Adams et al, 2001a).…”

“…Two dominant-negative mutants of INCENP cause cytokinesis defects in mammalian cells (Eckley et al, 1997;Mackay et al, 1998). Additionally, in C. elegans embryos and Drosophila cultured cells, depletion of INCENP causes a cytokinesis defect (Kaitna et al, 2000;Giet and Glover, 2001). Some of the requirements for INCENP during cytokinesis may be mediated by its partner, Aurora B. Aurora B can phosphorylate MgcRacGAP, a RhoA GAP important for the completion of cytokinesis (Minoshima et al, 2003).…”

Drosophila JIL-1 kinase mediates histone H3 Ser10 phosphorylation, maintains higher order chromatin structure, and is implicated in dosage compensation

“…Recent studies identified Ipll/aurora kinase as the mitotic histone H3 SerlO kinase and Glc7/PPl as the phosphatase catalyzing the reverse reaction to maintain the balance of SerlO phosphorylation (Hsu et al, 2000). Analysis of the D. melanogaster Aurora B kinase by a RNAi approach in Schneider 2 (S2) cells demonstrated that mitotic SerlO phosphorylation is controlled by the Aurora B kinase as well (Giet and Glover, 2001). …”