Centriole Loss in Embryonic Development Disrupts Axonal Pathfinding and Muscle Integrity
Centrosomes, the primary microtubule-organizing centres (MTOCs), are important during early neuronal development, contributing to polarity establishment and axon formation. Although once considered dispensable in differentiated cells, accumulating evidence suggests that centrosomes remain active in many cell types, with functions that depend on cellular context. In mammalian neurons, centrosome-dependent microtubule (MT) remodelling has been implicated in axon elongation, and centrosome dysfunction has been associated with axonal guidance defects. While active centrosomes have been observed in Drosophila melanogaster tracheal cells, their neuronal activity in vivo has remained unclear. Here, we examined Drosophila Sas-4 mutants, which undergo gradual centrosome loss (CL), and found that 50% of homozygous mutants fail to hatch. Analysis revealed the presence of centrosomes in wild-type motor and sensory neurons, with centrosomes localizing near nascent axons in motor neurons. Embryonic CL altered axonal routing and muscle organization, and targeted Sas-4 reduction in pioneer neurons produced mild guidance phenotypes. Centrosome MTOC activity was confirmed by tubulin localization and MT reassembly analyses. In addition, CL was associated with increased motor axon tortuosity, consistent with a contribution of centrosomes to neuronal morphology. Together, these findings indicate that centrosomes, while not acting as essential MTOCs in this context, contribute to MT dynamics and aspects of early axonal and muscle development.