?-Tubulin Ring Complexes and EB1 play antagonistic roles in microtubule dynamics and spindle positioning.

ABSTRACT: ?-Tubulin is critical for microtubule (MT) assembly and organization. In metazoa, this protein acts in multiprotein complexes called ?-Tubulin Ring Complexes (?-TuRCs). While the subunits that constitute ?-Tubulin Small Complexes (?-TuSCs), the core of the MT nucleation machinery, are essential, mutation of ?-TuRC-specific proteins in Drosophila causes sterility and morphological abnormalities via hitherto unidentified mechanisms. Here, we demonstrate a role of ?-TuRCs in controlling spindle orientation independent of MT nucleation activity, both in cultured cells and in vivo, and examine a potential function for ?-TuRCs on astral MTs. ?-TuRCs locate along the length of astral MTs, and depletion of ?-TuRC-specific proteins increases MT dynamics and causes the plus-end tracking protein EB1 to redistribute along MTs. Moreover, suppression of MT dynamics through drug treatment or EB1 down-regulation rescues spindle orientation defects induced by ?-TuRC depletion. Therefore, we propose a role for ?-TuRCs in regulating spindle positioning by controlling the stability of astral MTs.

SUBMITTER: Bouissou A 

PROVIDER: S-EPMC3989606 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature