Abstract
The sulfonylurea receptor 1 (Sur1)-NC(Ca-ATP) channel plays a central role in necrotic cell death in central nervous system (CNS) injury, including ischemic stroke, and traumatic brain and spinal cord injury. Here, we show that Sur1-NC(Ca-ATP) channels are formed by co-assembly of Sur1 and transient receptor potential melastatin 4 (Trpm4). Co-expression of Sur1 and Trpm4 yielded Sur1-Trpm4 heteromers, as shown in experiments with Förster resonance energy transfer (FRET) and co-immunoprecipitation. Co-expression of Sur1 and Trpm4 also yielded functional Sur1-Trpm4 channels with biophysical properties of Trpm4 and pharmacological properties of Sur1. Co-assembly with Sur1 doubled the affinity of Trpm4 for calmodulin and doubled its sensitivity to intracellular calcium. Experiments with FRET and co-immunoprecipitation showed de novo appearance of Sur1-Trpm4 heteromers after spinal cord injury in rats. Our findings depart from the long-held view of an exclusive association between Sur1 and K(ATP) channels and reveal an unexpected molecular partnership with far-ranging implications for CNS injury.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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ATP-Binding Cassette Transporters / antagonists & inhibitors
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ATP-Binding Cassette Transporters / metabolism*
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Animals
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COS Cells
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Cell Membrane / drug effects
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Cell Membrane / metabolism
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Chlorocebus aethiops
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Diazoxide / pharmacology
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Fluorescence Resonance Energy Transfer
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Glyburide / pharmacology
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Glycosylation / drug effects
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HEK293 Cells
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Humans
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Immunoprecipitation
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Mice
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Potassium Channels, Inwardly Rectifying / antagonists & inhibitors
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Potassium Channels, Inwardly Rectifying / metabolism*
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Protein Binding / drug effects
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Protein Multimerization / drug effects
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Rats
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Receptors, Drug / antagonists & inhibitors
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Receptors, Drug / metabolism*
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Recombinant Proteins / metabolism
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Spinal Cord Injuries / metabolism
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Spinal Cord Injuries / pathology
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Sulfonylurea Receptors
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TRPM Cation Channels / metabolism*
Substances
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ABCC8 protein, human
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ATP-Binding Cassette Transporters
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Abcc8 protein, mouse
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Abcc8 protein, rat
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Potassium Channels, Inwardly Rectifying
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Receptors, Drug
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Recombinant Proteins
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Sulfonylurea Receptors
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TRPM Cation Channels
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TRPM4 protein, mouse
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TRPM4 protein, rat
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Diazoxide
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Glyburide