γ-Tubulin ring complexes regulate microtubule plus end dynamics

gamma-Tubulin is critical for the initiation and regulation of microtubule (MT) assembly. In Drosophila melanogaster, it acts within two main complexes: the gamma-tubulin small complex (gamma-TuSC) and the gamma-tubulin ring complex (gamma-TuRC). Proteins specific of the gamma-TuRC, although nonessential for viability, are required for efficient mitotic progression. Until now, their role during interphase remained poorly understood. Using RNA interference in Drosophila S2 cells, we show that the gamma-TuRC is not critical for overall MT organization. However, depletion of any component of this complex results in an increase of MT dynamics. Combined immunofluorescence and live imaging analysis allows us to reveal that the gamma-TuRC localizes along interphase MTs and that distal gamma-tubulin spots match with sites of pause or rescue events. We propose that, in addition to its role in nucleation, the gamma-TuRC associated to MTs may regulate their dynamics by limiting catastrophes.