HAUS4 is part of the HAUS augmin-like complex, which contributes to mitotic spindle assembly, maintenance of chromosome integrity and completion of cytokinesis [, ].Human augmin complex is composed of 8 subunits and interacts with the gamma-tubulin ring complex (gamma-TuRC) in centrosomes []. This interaction affects MT generation during mitosis and is critical for chromosome segregation and cytokinesis in human cells []. Similar to humans, Arabidopsis augmin complex also contains 8 subunits, including AUGMIN subunit 4 (AUG4) in this entry []. Despite lacking cetrosomes, the augmin complex in Arabidopsis also plays an important part in gamma-tubulin-dependent MT nucleation and the assembly of microtubule arrays during mitosis [].
HAUS4 contributes to mitotic spindle assembly, maintenance of centrosome integrity and completion of cytokinesis as part of the HAUS augmin-like complex [, ].Assembly of a robust microtubule-based mitotic spindle is essential for accurate segregation of chromosomes to progeny. Spindle assembly relies on the concerted action of centrosomes, spindle microtubules, molecular motors and non-motor spindle proteins. 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 [, ].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 [].The HAUS (Homologous to AUgmin Subunits) individual subunits have been designated HAUS1 to HAUS8 []. The HAUS augmin-like complex subunit 4 was previously known as C14orf94.
