The augmin complex plays a critical role in spindle microtubule generation for mitotic progression and cytokinesis in human cells.
The mitotic spindle is constructed from microtubules (MTs) nucleated from centrosomes, chromosome proximal regions, and preexisting spindle MTs. Augmin, a recently identified protein complex, is a critical factor in spindle MT-based MT generation in Drosophila S2 cells. Previously, we identified one subunit of human augmin. Here, by using mass spectrometry, we identified the full human augmin complex of 8 subunits and show that it interacts with the gamma-tubulin ring complex (gamma-TuRC). Unlike augmin-depleted S2 cells, in which the defect in spindle-mediated MT generation is mostly compensated by centrosomal MTs, augmin knockdown alone in HeLa cells triggers the spindle checkpoint, reduces tension on sister kinetochores, and severely impairs metaphase progression. Human augmin knockdown also reduces the number of central spindle MTs during anaphase and causes late-stage cytokinesis failure. A link between augmin and gamma-TuRC is likely critical for these functions, because a gamma-TuRC mutant that attenuates interaction with augmin does not restore function in vivo. These results demonstrate that MT generation mediated by augmin and gamma-TuRC is critical for chromosome segregation and cytokinesis in human cells.
Uehara
Ryota
R
Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Nozawa
Ryu-suke
RS
Tomioka
Akiko
A
Petry
Sabine
S
Vale
Ronald D
RD
Obuse
Chikashi
C
Goshima
Gohta
G
D000818:Animals; D048749:Cytokinesis; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000378:metabolism; D008677:Metaphase; D008870:Microtubules / Q000378:metabolism*; D008938:Mitosis; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D008941:Spindle Apparatus / Q000378:metabolism*
D046912:Multiprotein Complexes; D021122:Protein Subunits