From tip to toe - dressing centrioles in gamma TuRC

Abstract

Centrioles are microtubule-based cylindrical structures that assemble the centrosome and template the formation of cilia. The proximal part of centrioles is associated with the pericentriolar material, a protein scaffold from which microtubules are nucleated. This activity is mediated by the.-tubulin ring complex (gamma TuRC) whose central role in centrosomal microtubule organization has been recognized for decades. However, accumulating evidence suggests that gamma TuRC activity at this organelle is neither restricted to the pericentriolar material nor limited to microtubule nucleation. Instead, gamma TuRC is found along the entire centriole cylinder, at subdistal appendages, and inside the centriole lumen, where its canonical function as a microtubule nucleator might be supplemented or replaced by a function in microtubule anchoring and centriole stabilization, respectively. In this Opinion, we discuss recent insights into the expanded repertoire of gamma TuRC activities at centrioles and how distinct subpopulations of gamma TuRC might act in concert to ensure centrosome and cilia biogenesis and function, ultimately supporting cell proliferation, differentiation and homeostasis. We propose that the classical view of centrosomal gamma TuRC as a pericentriolar material-associated microtubule nucleator needs to be revised.