Neuronal dendrites require microtubules (MTs) for the growth and branching of their complex structure. MT nucleation is mediated by γ-tubulin ring complexes (γ-TuRCs), which can be recruited to pre-existing MTs by the augmin complex, promoting branched MT nucleation events. Although augmin and γ-TuRCs are important for correct MT organisation and neuronal growth in culture, their significance in vivo is less clear. Now, two groups independently demonstrate that augmin and γ-TuRCs are important for dendritic growth and branching in vivo in Drosophila dendritic arborisation (da) neurons. In one study (Mukherjee et al., 2024), Paul Conduit and colleagues show that depletion of γ-TuRCs from highly branching class IV da neurons strongly perturbs dendritic growth and branching. Additionally, augmin depletion specifically reduces higher-order branching, attributed to reduced MT growth within terminal dendrites, which are consequently destabilised. In another study (Zhang et al., 2024), Anna Ziegler, Gaia Tavosanis and colleagues also use class IV da neurons to show that MT density is maintained through augmin and γ-TuRCs, where their depletion also results in a reduction in higher-order dendritic branches, something also attributed to reduced MT growth within terminal dendrites. Taken together, these two studies corroborate an important role for γ-TuRCs within neurons in vivo and highlight augmin as a factor that promotes higher-order dendritic branching.
