DNA topoisomerase IIβ and neural development

DNA topoisomerase II beta is shown to have an unsuspected and critical role in neural development. Neurogenesis was normal in II beta mutant mice, but motor axons failed to contact skeletal muscles, and sensory axons failed to enter the spinal cord. Despite an absence of innervation, clusters of acetylcholine receptors were concentrated in the central region of skeletal muscles, thereby revealing patterning mechanisms that are autonomous to skeletal muscle. The defects in motor axon growth in II beta mutant mice resulted in a breathing impairment and death of the pups shortly after birth.