RRC ID 56203
Author Nam YW, Baskoylu SN, Gazgalis D, Orfali R, Cui M, Hart AC, Zhang M.
Title A V-to-F substitution in SK2 channels causes Ca2+ hypersensitivity and improves locomotion in a C. elegans ALS model.
Journal Sci Rep
Abstract Small-conductance Ca2+-activated K+ (SK) channels mediate medium afterhyperpolarization in the neurons and play a key role in the regulation of neuronal excitability. SK channels are potential drug targets for ataxia and Amyotrophic Lateral Sclerosis (ALS). SK channels are activated exclusively by the Ca2+-bound calmodulin. Previously, we identified an intrinsically disordered fragment that is essential for the mechanical coupling between Ca2+/calmodulin binding and channel opening. Here, we report that substitution of a valine to phenylalanine (V407F) in the intrinsically disordered fragment caused a ~6 fold increase in the Ca2+ sensitivity of SK2-a channels. This substitution resulted in a novel interaction between the ectopic phenylalanine and M411, which stabilized PIP2-interacting residue K405, and subsequently enhanced Ca2+ sensitivity. Also, equivalent valine to phenylalanine substitutions in SK1 or SK3 channels conferred Ca2+ hypersensitivity. An equivalent phenylalanine substitution in the Caenorhabditis elegans (C. elegans) SK2 ortholog kcnl-2 partially rescued locomotion defects in an existing C. elegans ALS model, in which human SOD1G85R is expressed at high levels in neurons, confirming that this phenylalanine substitution impacts channel function in vivo. This work for the first time provides a critical reagent for future studies: an SK channel that is hypersensitive to Ca2+ with increased activity in vivo.
Volume 8(1)
Pages 10749
Published 2018-7-16
DOI 10.1038/s41598-018-28783-2
PII 10.1038/s41598-018-28783-2
PMID 30013223
PMC PMC6048120
MeSH Amyotrophic Lateral Sclerosis / genetics* Amyotrophic Lateral Sclerosis / pathology Animals Animals, Genetically Modified Caenorhabditis elegans Calcium / metabolism* Calmodulin / metabolism Cells, Cultured Disease Models, Animal Humans Intrinsically Disordered Proteins / genetics* Intrinsically Disordered Proteins / metabolism Locomotion / genetics* Membrane Potentials / genetics Neurons / metabolism Phenylalanine / genetics Small-Conductance Calcium-Activated Potassium Channels / genetics* Small-Conductance Calcium-Activated Potassium Channels / metabolism Superoxide Dismutase-1 / genetics Superoxide Dismutase-1 / metabolism Valine / genetics
IF 4.011
Resource
C.elegans tm776