Maintenance of muscle innervation
Are the same gene networks necessary for the establishment and maintenance of muscle innervation?
Each motoneuron axon terminal innervates specific muscle fibers and displays an unique architecture defined by their shape and number of synaptic boutons The unique wiring and architecture of motoneuron axon terminals ensure the proper contraction of muscles allowing correct movements. In adult, the maintenance of muscle innervation architecture is essential to keep the locomotor system functional. Motoneuron axon terminals are dynamic structures. Those innervating Drosophila flight muscles are dismantled and reestablished every day. During the night, the number of synaptic boutons decreases, while the correct number of boutons is restored during the day. Despite the dynamic nature of the motoneuron axon terminals, their unique wiring and architecture is always maintained. Peripheral nerves damaged by mechanical, chemical and biological stresses have the capacity to regenerate. For example, ablation of wing sensory neurons in Drosophila is followed by axon regeneration. In Crayfish, when a motor nerve is cut, it regenerates and innervates again the correct muscles. In humans, when a peripheral nerve is injured, axons regrow with a speed of 1 mm per day and muscle function can be recovered. Thus, the maintenance of muscle innervation across physiological conditions or after injury must preserve unique wiring and architecture of motoneuron axon terminals to sustain locomotor function.
To achieve our goal, we combine RNA profiling of motoneurons and muscles with state-of-the-art techniques and a newly designed genetic tool to visualize and modify the genotype of cells adult flies, and determine the impact of these manipulations on locomotion with unique behavioral technologies (Flywalker).