Bowerman M, Salsac C, Bernard V, Soulard C, Dionne A, Coque E, Benlefki S, Hince P, Dion PA, Butler-Browne G, Camu W, Bouchard JP, Delpire E, Rouleau GA, Raoul C, Scamps F. KCC3 loss-of-function contributes to Andermann syndrome by inducing activity-dependent neuromuscular junction defects. Neurobiology of disease. 2017 Jun 21;106(106). 35-48. PMID: 28647557 [PubMed]
Loss-of-function mutations in the potassium-chloride cotransporter KCC3 lead to Andermann syndrome, a severe sensorimotor neuropathy characterized by areflexia, amyotrophy and locomotor abnormalities. The molecular events responsible for axonal loss remain poorly understood. Here, we establish that global or neuron-specific KCC3 loss-of-function in mice leads to early neuromuscular junction (NMJ) abnormalities and muscular atrophy that are consistent with the pre-synaptic neurotransmission defects observed in patients. KCC3 depletion does not modify chloride handling, but promotes an abnormal electrical activity among primary motoneurons and mislocalization of Na(+)/K(+)-ATPase α1 in spinal cord motoneurons. Moreover, the activity-targeting drug carbamazepine restores Na(+)/K(+)-ATPase α1 localization and reduces NMJ denervation in Slc12a6(-/-) mice. We here propose that abnormal motoneuron electrical activity contributes to the peripheral neuropathy observed in Andermann syndrome.