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Principal Investigator: Christopher A Ahern
Organization: UNIVERSITY OF IOWA
Fiscal Year: 2024
Award: $466,355
Funding agency: National Heart Lung and Blood Institute
Abstract
Voltage-gated sodium channels (NaVs) maintain the electrical cadence in cardiac muscle tissues by
selectively controlling the rapid inward passage of sodium. The NaV complex is comprised of a 260-kDa pore-
forming α-subunit (encoded primarily by NaV1.5 in heart) that partners with β -subunits (β1-β4) comprised of a
single transmembrane segment and exofacial immunoglobulin (Ig) fold. These β-subunits belong to a larger
family of β/MPZ proteins that includes other single pass Ig proteins such as MPZ(P0). Defects in sodium
channel function resulting from inherited mutations in either the α or β subunits are established causes of
human disease, and are associated with sudden infant death, atrial fibrillation, reperfusion and ischemia injury,
arrhythmia in the failing heart, epilepsy, and a variety of pain-causing syndromes. Other forms of heart disease
that develop later in life and that are exacerbated by obesity are also characterized by altered sodium channel
activity, in particular the inability to quickly and completely inactivate during the course of the cardiac action
potential.
The β-subunits have been proposed to regulate essentially every aspect of the pore-forming α subunit;
including protein complex trafficking and turn-over, voltage-dependent function, and pharmacology. However,
the molecular bases for these wide-ranging effects are poorly resolved primarily because the ‘gold standard’
heterologous cells that are used for ion channel characterization and high-throughput screening exhibit near
ubiquitous expression of β-subunits, and their near relatives. As such, the variability amongst expression
systems has stymied systematic study of β-subunit function. This in turn has prevented translational studies to
examine the effect of various β subunit disease-associated mutants as well as efforts to identify drugs that may
specifically modify specific α/β NaV complexes. We recently generated a CRISPR-modified human haploid cell
line that lacks multiple members of the β/MPZ family including β1-β4. Electrophysiological experiments with
these cells have revealed new emergent properties of NaV1.5 in the absence and presence of β subunits.
These data provide the proof-of-concept that mammalian cells lacking the β/MPZ family will provide a powerful
and needed way to specifically study many aspects of particular NaV α/β complexes, allowing better
fundamental structure/function studies, better understanding of how disease-causing mutations in both α and β
subunits cause pathology, and more precise tools for drug screening and drug safety profile testing.
Terms: <Action Potentials><Affect><Arrhythmia><Assay><Atrial Fibrillation><Auricular Fibrillation><Bioassay><Biological Assay><CRISPR><CRISPR/Cas system><Cardiac><Cardiac Arrhythmia><Cardiac Diseases><Cardiac Disorders><Cell Body><Cell Line><Cell Size><CellLine><Cells><Characteristics><Cholesterol><Clinical><Clustered Regularly Interspaced Short Palindromic Repeats><Complex><Cot Death><Crib Death><Cultured Cells><Cytoplasm><Data><Defect><Development><Disease><Disorder><Drug Screening><Drugs><Electrophysiology><Electrophysiology (science)><Engineering><Ensure><Epilepsy><Epileptic Seizures><Epileptics><Exhibits><Family><Family member><Gene Family><Genes><Genetic Alteration><Genetic Change><Genetic defect><Goals><Haploid Cells><Heart><Heart Arrhythmias><Heart Diseases><Hereditary><High Throughput Assay><Human><Immune Globulins><Immunoglobulins><InAs><Individual><Inherited><Intervention><Intervention Strategies><Ion Channel><Ionic Channels><Ischemia-Reperfusion Injury><Isoforms><Life><Lipids><Mammalian Cell><Manuals><Medication><Membrane><Membrane Channels><Modality><Modern Man><Molecular><Muscle><Muscle Tissue><Mutation><Myocardium><Na element><Na(v)1.1><Nav1.1><Neurophysiology / Electrophysiology><Obesity><Outcome><Pain><Painful><Pathology><Performance><Pharmaceutical Preparations><Pharmacology><Property><Protein Isoforms><Proteins><Reperfusion Damage><Reperfusion Injury><Research><SCN1A protein><SIDS><Seizure Disorder><Sodium><Sodium Channel><Sodium Ion Channels><Specificity><Strains Cell Lines><Structure><Sudden Infant Death><Sudden Unexpected Infant Death><Sudden infant death syndrome><Syndrome><System><Testing><Transgenes><Variant><Variation><Xenopus oocyte><adiposity><base><bases><cardiac muscle><clinical relevance><clinically relevant><corpulence><cultured cell line><developmental><disease causing variant><disease-causing mutation><drug development><drug safety><drug/agent><effective therapy><effective treatment><electrophysiological><epilepsia><epileptogenic><experiment><experimental research><experimental study><experiments><genome mutation><heart disorder><heart muscle><high throughput screening><human disease><indium arsenide><instrument><interventional strategy><ischemia injury><ischemic injury><medication safety><member><membrane structure><muscular><mutant><new drug treatments><new drugs><new pharmacological therapeutic><new therapeutics><new therapy><next generation therapeutics><novel drug treatments><novel drugs><novel pharmaco-therapeutic><novel pharmacological therapeutic><novel therapeutics><novel therapy><patch clamp><pathogenic variant><pharmaceutical safety><pharmacologic><prevent><preventing><protein complex><tool><trafficking><transgene><translational study><voltage>