The small molecule Hesperadin reveals a role for Aurora B in correcting kinetochore–microtubule attachment and in maintaining the spindle assembly checkpoint

Abstract

The proper segregation of sister chromatids in mitosis depends on bipolar attachment of all chromosomes to the mitotic spindle. We have identified the small molecule Hesperadin as an inhibitor of chromosome alignment and segregation. Our data imply that Hesperadin causes this phenotype by inhibiting the function of the mitotic kinase Aurora B. Mammalian cells treated with Hesperadin enter anaphase in the presence of numerous monooriented chromosomes, many of which may have both sister kinetochores attached to one spindle pole (syntelic attachment). Hesperadin also causes cells arrested by taxol or monastrol to enter anaphase within <1 h, whereas cells in nocodazole stay arrested for 3–5 h. Together, our data suggest that Aurora B is required to generate unattached kinetochores on monooriented chromosomes, which in turn could promote bipolar attachment as well as maintain checkpoint signaling.

SAC‐ing mitotic errors: How the spindle assembly checkpoint (SAC) plays defense against chromosome mis‐segregation

“…The mammalian Ndc80p complex [McCleland et al, 2003], the ROD and ZW10 kinetochore proteins [Basto et al, 2000;Chan et al, 2000], the outer kinetochore protein Zwint-1 [Obuse et al, 2004;Wang et al, 2004a], and the kinetochore-associated NEK2A protein [Lou et al, 2004] are also required for the spindle checkpoint, indicating that the kinetochore's role in SAC signaling is evolutionarily conserved, although no ROD, ZW10, or Zwint-1 homologues have been identified in yeast. The mammalian survivin/Aurora B complex regulates BubR1p and Mad2p localization to kinetochores [Lens et al, 2003] and, like the budding yeast Ipl1p/Aurora, is required for SAC function when insufficient tension is applied across sister kinetochores [Carvalho et al, 2003;Hauf et al, 2003;Lens et al, 2003]. …”

Identification of genes that confer tumor cell resistance to the Aurora B kinase inhibitor, AZD1152

“…Several small-molecule inhibitors have been developed including Hesperadin, ZM447439, VX-680/MK0457, AZD1152 and MLN8054. [6][7][8][9] AZD1152 is a novel acetanilide-substituted pyrazole-aminoquinazoline prodrug that is rapidly converted to the active drug, AZD1152 HQPA, in human plasma. 10 AZD1152 HQPA is a highly potent and selective inhibitor of Aurora B (K i of 0.36 nM) compared to Aurora A (K i of 1369 nM) and is inactive against a panel of 50 other kinases.…”

An integrated pharmacokinetic–pharmacodynamic model for an Aurora kinase inhibitor

“…Mad2 can directly interact with Cdc20 and inhibit the activation of APC/C [37]. Treatment of cells with AK-B inhibitors caused chromosome alignment problems, spindle checkpoint override and cytokinesis failure [34,38,39]. From the above observations and following [22], it can therefore be reasonably hypothesised that: (i) AK-A inhibition reduces all net transition rates in the state transition framework in Fig.…”

“…Depletion of AK-A, in cells that contained a correct bipolar spindle structure, resulted in a checkpoint dependent prolonged mitosis caused by unstable kinetochore-microtubule attachments [32]. Incorrect kinetochore-microtubule attachments can be resolved by AK-B [33]: if either a merotelic or syntelic attachment occurs, AK-B severs the kinetochore-microtubule attachment [1,34,35]. Consequently, AK-B inhibition retards the repair of incorrect microtubule-kinetochore attachment [32,34].…”

“…Incorrect kinetochore-microtubule attachments can be resolved by AK-B [33]: if either a merotelic or syntelic attachment occurs, AK-B severs the kinetochore-microtubule attachment [1,34,35]. Consequently, AK-B inhibition retards the repair of incorrect microtubule-kinetochore attachment [32,34]. Also, it has been observed that both AK-A and B mediate the recruitment of checkpoint proteins to the kinetochore, including Bub1, BubR1, CENP-E, Bub3, Mad1, and Mad2 [36].…”