Centrosome Loss in Embryonic Development Disrupts Axonal Pathfinding and Muscle Integrity

Centrosomes, the primary microtubule-organizing centres (MTOCs), are essential during early neuronal development, contributing to polarity establishment and axon formation. Although once considered unnecessary in differentiated cells, evidence shows that centrosomes remain active in many cells, with roles depending on cellular context. In mammalian neurons, centrosome-driven microtubule (MT) remodelling supports axon elongation, and centrosome dysfunction causes axonal guidance defects. While active centrosomes have been observed in Drosophila melanogaster tracheal cells, their neuronal activity in vivo remained unclear. Here, we examined Drosophila Sas-4 mutants, which undergo centrosome loss (CL), and found that 50% of homozygous mutants fail to hatch. Analysis revealed that centrosomes are present in wild-type motor and sensory neurons, localizing near nascent axons in motor neurons. Complete centrosome loss caused axonal misrouting and muscle abnormalities, while targeted Sas-4 reduction in pioneer neurons produced subtle guidance defects. Active centrosomes were confirmed through tubulin localization and MT reassembly studies. CL increased motor axon tortuosity, linking centrosomes to neuronal morphology. These findings demonstrate that centrosomes are not essential MTOCs but regulate MT dynamics and early axonal development.