title: Semaphorin 3A signaling through neuropilin-1 is an early trigger for distal axonopathy in the SOD1G93A mouse model of amyotrophic lateral sclerosis.
abstract: Amyotrophic lateral sclerosis (ALS) is a motor neuron disease characterized by progressive distal axonopathy that precedes actual motor neuron death. Triggers for neuromuscular junction degeneration remain to be determined, but the axon repulsion factor semaphorin 3A (Sema3A), which is derived from terminal Schwann cells, is a plausible candidate. This study examines the hypothesis that Sema3A signaling through its motor neuron neuropilin-1 (NRP1) receptor triggers distal axonopathy and muscle denervation in the SOD1 mouse model of ALS. Neuropilin-1 was found to be expressed in axonal terminals at the mouse neuromuscular junction in vivo and in NSC-34 motor neuron-like cells in vitro. In differentiated NSC-34 cells, an anti-NRP1 antibody that selectively blocks Sema3A binding to NRP1 prevented Sema3A-induced growth cone collapse. Furthermore, intraperitoneal injections of anti-NRP1 antibody administered twice weekly from age 40 days significantly delayed and even temporarily reversed motor functional decline while prolonging the life span of SOD1 mice. Histologic evaluation at 90 and 125 days revealed that anti-NRP1 antibody reduced neuromuscular junction denervation and attenuated pathologic alterations in ventral roots at late-stage disease. These data suggest that peripheral NRP1 signaling is involved in the pathobiology of this ALS model and that antagonizing Sema3A/NRP1 binding or downstream signals could have implications for the treatment of ALS.
authors.affiliation: From the Departments of Pathology (KV, AC, ZK, SS, KH) and Neurosciences (KH), University of Toledo Health Sciences Campus, Toledo, Ohio; and Department of Pathology, University of California at San Diego, San Diego, California (PK).
authors.forename: Kalina
authors.initials: K
authors.lastname: Venkova
authors.forename: Alexander
authors.initials: A
authors.lastname: Christov
authors.forename: Zarine
authors.initials: Z
authors.lastname: Kamaluddin
authors.forename: Peter
authors.initials: P
authors.lastname: Kobalka
authors.forename: Saaid
authors.initials: S
authors.lastname: Siddiqui
authors.forename: Kenneth
authors.initials: K
authors.lastname: Hensley
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000473:pathology*; D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D001369:Axons / Q000473:pathology*; D002478:Cells, Cultured; D003627:Data Interpretation, Statistical; D005260:Female; D007150:Immunohistochemistry; D051379:Mice; D009046:Motor Neurons / Q000378:metabolism; D009469:Neuromuscular Junction / Q000473:pathology; D039942:Neuropilin-1 / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology; D040121:Semaphorin-3A / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013126:Spinal Nerve Roots / Q000473:pathology; D013482:Superoxide Dismutase / Q000235:genetics*; D000072105:Superoxide Dismutase-1; D016019:Survival Analysis
chemical_list: D019138:Antibodies, Blocking; D040121:Semaphorin-3A; D039942:Neuropilin-1; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1