Axonal Charcot–Marie–Tooth disease patient-derived motor neurons demonstrate disease-specific phenotypes including abnormal electrophysiological properties

• Published in: Experimental neurology Vol. 263; pp. 190 - 199
• Main Authors: Saporta, Mario A., Dang, Vu, Volfson, Dmitri, Zou, Bende, Xie, Xinmin (Simon), Adebola, Adijat, Liem, Ronald K., Shy, Michael, Dimos, John T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2015
• Subjects: Adult; Animals; Axonal Charcot–Marie–Tooth disease; Axonal transport; Cell Separation; Charcot-Marie-Tooth Disease - genetics; Charcot-Marie-Tooth Disease - pathology; Charcot-Marie-Tooth Disease - physiopathology; Child; Electrophysiological Phenomena; Electrophysiology; Female; Gene Knock-In Techniques; GTP Phosphohydrolases - genetics; Humans; Induced Pluripotent Stem Cells; Inherited Neuropathies; Intermediate Filaments - pathology; Male; Mice; Mitochondria - pathology; Mitochondrial Proteins - genetics; Motor neurons; Motor Neurons - pathology; Neurofilament Proteins - genetics; Patch-Clamp Techniques; Phenotype; Point Mutation; Real-Time Polymerase Chain Reaction; Electrophysiology; Motor neurons; Inherited Neuropathies; Axonal Charcot–Marie–Tooth disease; Axonal transport; Induced pluripotent stem cells
• ISSN: 0014-4886; 1090-2430; 1090-2430
• DOI: 10.1016/j.expneurol.2014.10.005

Charcot–Marie–Tooth (CMT) disease is a group of inherited peripheral neuropathies associated with mutations or copy number variations in over 70 genes encoding proteins with fundamental roles in the development and function of Schwann cells and peripheral axons. Here, we used iPSC-derived cells to identify common pathophysiological mechanisms in axonal CMT. iPSC lines from patients with two distinct forms of axonal CMT (CMT2A and CMT2E) were differentiated into spinal cord motor neurons and used to study axonal structure and function and electrophysiological properties in vitro. iPSC-derived motor neurons exhibited gene and protein expression, ultrastructural and electrophysiological features of mature primary spinal cord motor neurons. Cytoskeletal abnormalities were found in neurons from a CMT2E (NEFL) patient and corroborated by a mouse model of the same NEFL point mutation. Abnormalities in mitochondrial trafficking were found in neurons derived from this patient, but were only mildly present in neurons from a CMT2A (MFN2) patient. Novel electrophysiological abnormalities, including reduced action potential threshold and abnormal channel current properties were observed in motor neurons derived from both of these patients. Human iPSC-derived motor neurons from axonal CMT patients replicated key pathophysiological features observed in other models of MFN2 and NEFL mutations, including abnormal cytoskeletal and mitochondrial dynamics. Electrophysiological abnormalities found in axonal CMT iPSC-derived human motor neurons suggest that these cells are hyperexcitable and have altered sodium and calcium channel kinetics. These findings may provide a new therapeutic target for this group of heterogeneous inherited neuropathies. •Patient-derived spinal motor neurons closely resemble primary neurons.•CMT2E neurons have disrupted neurofilament and axonal mitochondrial dynamics.•CMT2A and CMT2E neurons are hyperexcitable and have altered ion channel kinetics.•Therefore, our results suggest a novel potential target for drug therapy in CMT.•Our data supports the use of cellular reprogramming to study Inherited Neuropathies.