noncentrosomal

Noncentrosomal refers to microtubule organizing activity that occurs independently of the centrosome, the major MTOC in many animal cells. In noncentrosomal organization, microtubules are nucleated and/or stabilized at alternative sites within the cytoplasm, at organelles such as the Golgi apparatus or nuclear envelope, or at cortical sites near the cell cortex. This leads to noncentrosomal microtubule arrays that support specialized cell architectures and functions.

In many differentiated cells, centrosomes are reduced in their role as MTOCs, and noncentrosomal MTOCs take on nucleation and anchoring duties. Gamma-tubulin ring complexes and other nucleation factors can be recruited to noncentrosomal sites, and a class of minus-end–stabilizing and -anchoring proteins, including CAMSAPs and ninein, helps organize noncentrosomal arrays. Golgi-anchored MTOCs, mediated by proteins that tether gamma-tubulin to the Golgi, provide a prominent example of noncentrosomal organization in mammalian cells.

Biological contexts include neural, epithelial, and muscle tissues, where noncentrosomal arrays contribute to cell polarity, directed vesicle transport, and proper tissue architecture. In neurons, microtubules organize in dendrites and axons largely without centrosomal input. Plant cells also rely on noncentrosomal mechanisms for cortical microtubule arrays, as conventional centrosomes are absent.

Studied for understanding development, polarity, and disease, noncentrosomal organization is investigated through imaging of microtubules and centrosomal components, and by perturbing noncentrosomal nucleation factors. Disruptions of noncentrosomal MTOCs have been linked to developmental defects and neurological disorders, underscoring their functional importance.