InterPro domain: IPR026243

Assembly of a robust microtubule-based mitotic spindle is essential for accurate segregation of chromosomes to progeny [ 1 ]. Spindle assembly relies on the concerted action of centrosomes, spindle microtubules, molecular motors and non-motor spindle proteins [ 2 ]. A number of novel regulators of spindle assembly have been identified: one of these is HAUS, an 8-subunit protein complex that shares similarity with Drosophila Augmin [ 2 , 2 ]. Plants also have a augmin complex consisting of eight subunits. Subunits AUG1 to AUG6 can be aligned with the human HAUS1 to HAUS6 proteins [ 3 ].

HAUS localises to interphase centrosomes and to mitotic spindle micro- tubules; its disruption induces microtubule-dependent fragmentation of centrosomes, and an increase in centrosome size. HAUS disruption results in the destabilisation of kinetochore microtubules and eventual formation of multipolar spindles. Such severe mitotic defects are alleviated by co-depletion of NuMA, indicating that both factors regulate opposing activities. HAUS disruption alters NuMA localisation, suggesting that mis-localised NuMA activity contributes to the observed spindle and centrosome defects. The Augmin complex (HAUS) is thus a critical, evolutionarily conserved multi-subunit protein complex that regulates centrosome and spindle integrity [ 4 ].

The HAUS (Homologous to AUgmin Subunits) individual subunits have been designated HAUS1 to HAUS8 [ 4 ]. HAUS augmin-like complex subunit 1 (also known as enhancer of invasion-cluster, HEI-C [ 4 ], and coiled-coil domain-containing protein 5) is a coiled-coil protein required for passage through mitosis [ 4 ].

1. HAUS, the 8-subunit human Augmin complex, regulates centrosome and spindle integrity. Curr. Biol. 19, 816-26
2. The augmin complex plays a critical role in spindle microtubule generation for mitotic progression and cytokinesis in human cells. Proc. Natl. Acad. Sci. U.S.A. 106, 6998-7003
3. Characterization of the Arabidopsis augmin complex uncovers its critical function in the assembly of the acentrosomal spindle and phragmoplast microtubule arrays. Plant Cell 24, 1494-509
4. Human enhancer of invasion-cluster, a coiled-coil protein required for passage through mitosis. Mol. Cell. Biol. 24, 3957-71