title: Antisense peptide nucleic acid targeting GluR3 delays disease onset and progression in the SOD1 G93A mouse model of familial ALS.
abstract: Glutamate excitotoxicity is strongly implicated as a major contributing factor in motor neuron degeneration in amyotrophic lateral sclerosis (ALS). Excitotoxicity results from elevated intracellular calcium ion (Ca(2+)) levels, which in turn recruit cell death signaling pathways. Recent evidence suggests that alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunit (GluR) stoichiometry is a dominant factor leading to excess Ca(2+) loading in neurodegeneration. In particular, the Ca(2+) permeable glutamate receptor subunit 3 (GluR3) has been implicated in several neurologic conditions such as bipolar disorder and epilepsy. Recent proteomic analysis within our group on the copper zinc superoxide dismutase (SOD1)(G93A) transgenic mouse model of familial ALS (FALS) reveals a potentially deleterious upregulation of GluR3 in spinal cord compared to that in wild-type littermates. Based on this finding we designed a 12mer antisense peptide nucleic acid (PNA) directed against GluR3. This sequence significantly reduced levels of GluR3 protein and protected neuroblastoma x spinal cord (NSC-34) cells against death induced by the AMPA receptor-specific agonist (S)-5-fluorowillardiine. We subsequently treated SOD1(G93A) mice thrice weekly with intraperitoneal injections of the antisense PNA (2.5 mg/kg) commencing at postnatal day 50. Mice treated with the antisense sequence had significantly extended survival compared to mice injected with a nonsense sequence. Western blot analysis, however, did not reveal a significant reduction in GluR3 protein levels in whole extracts of the lumbar spinal cord. These results suggest that interference with the GluR3 component of the AMPA receptor assembly may be a novel strategy for controlling excitotoxic destruction of motor neurons and may lead to new therapeutic opportunities for the treatment of human ALS.
authors.affiliation: Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Victoria, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Rembach
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Turner
authors.forename: Stephen
authors.initials: S
authors.lastname: Bruce
authors.forename: Irwin K
authors.initials: IK
authors.lastname: Cheah
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Scott
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Lopes
authors.forename: Chrissandra J
authors.initials: CJ
authors.lastname: Zagami
authors.forename: Philip M
authors.initials: PM
authors.lastname: Beart
authors.forename: Nam S
authors.initials: NS
authors.lastname: Cheung
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Langford
authors.forename: Surindar S
authors.initials: SS
authors.lastname: Cheema
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology / Q000235:genetics / Q000628:therapy*; D000818:Animals; D016375:Antisense Elements (Genetics) / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism / Q000633:toxicity; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D004195:Disease Models, Animal; D018450:Disease Progression; D015536:Down-Regulation / Q000187:drug effects* / Q000235:genetics; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D009410:Nerve Degeneration / Q000201:enzymology / Q000235:genetics / Q000628:therapy; D020135:Peptide Nucleic Acids / Q000494:pharmacology*; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D015996:Survival Rate
chemical_list: D016375:Antisense Elements (Genetics); D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D020135:Peptide Nucleic Acids; D018091:Receptors, AMPA; C104723:glutamate receptor ionotropic, AMPA 3; C109415:SOD1 G93A protein; D013482:Superoxide Dismutase; D002118:Calcium