Clenbuterol-sensitive delayed outward potassium currents in a cell model of spinal and bulbar muscular atrophy.

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by polyglutamine (polyQ) expansions in the androgen receptor (AR) gene. SBMA is characterized by selective dysfunction and degeneration of motor neurons in the brainstem and spinal cord through still unclear mechanisms in which ion channel modulation might play a central role as for other neurodegenerative diseases. The beta2-adrenergic agonist clenbuterol was observed to ameliorate the SBMA phenotype in mice and patient-derived myotubes. However, the underlying molecular mechanism has yet to be clarified. Here, we unveil that ionic current alterations induced by the expression of polyQ-expanded AR in motor neuron-derived MN-1 cells are attenuated by the administration of clenbuterol. Our combined electrophysiological and pharmacological approach allowed us to reveal that clenbuterol modifies delayed outward potassium currents. Overall, we demonstrated that the protection provided by clenbuterol restores the normal function through the modulation of K2-type outward potassium currents, possibly contributing to the protective effect on motor neuron toxicity in SBMA.