The role of BMP signalling in diseases of the motor unit (360G-Wellcome-205162_Z_16_Z)

Spinal and bulbar muscular atrophy (SBMA) is an X-linked, adult-onset, neuromuscular disease characterized by lower motor neuron degeneration as result of misfolding and accumulation of mutant Androgen Receptor (AR). In recent years this scenario of selective neuronal vulnerability has been challenged by the discovery that in SBMA, as in other diseases of the motor unit, skeletal muscle, rather than being a mere bystander of motor neuron degeneration, is primarily affected and therapies exclusively targeting muscle ameliorate the pathology in motor neuron while preventing the development of a neuromuscular phenotype in animal models. My goal is to elucidate the molecular mechanisms underlying the intrinsic contribution of skeletal muscle in SBMA pathogenesis. I will investigate the role of the Bone Morphogenetic Protein (BMP) signalling pathway in SBMA pathophysiology, testing the central hypothesis that failure to activate the protective BMP pathway in SBMA muscle in response to denervation causes primary muscle atrophy and affects motor neuron ability to cope with the stress posed by mutant AR. The rationale is to provide a molecular basis for the cell-autonomous and non-cell autonomous roles of muscle in the mechanisms of toxicity in SBMA and other diseases of the motor unit and to identify novel therapeutic targets.