DOI: 10.5061/dryad.jdfn2z3fs
title: Data from: NaV1.6 dysregulation within myocardial T-tubules by D96V calmodulin enhances proarrhythmic sodium and calcium mishandling

description: Calmodulin (CaM) plays critical roles in cardiomyocytes, regulating Na+
 (NaV) and L-type Ca2+ channels (LTCC). LTCC dysregulation by mutant CaMs
 has been implicated in action potential duration (APD) prolongation and
 arrhythmogenic long QT (LQT) syndrome. Intriguingly, D96V-CaM prolongs APD
 more than other LQT-associated CaMs despite inducing comparable levels of
 LTCC dysfunction, suggesting dysregulation of other depolarizing channels.
 Here, we provide evidence implicating NaV dysregulation within transverse
 (T)-tubules in D96V-CaM-associated arrhythmias. D96V-CaM induces
 pro-arrhythmic late Na+ current (INa) by impairing inactivation of NaV1.6,
 but not the predominant cardiac NaV isoform, NaV1.5. We investigated
 arrhythmia mechanisms using mice with cardiac-specific expression of
 D96V-CaM (cD96V). Super-resolution microscopy revealed close proximity of
 NaV1.6 and RyR2 within T-tubules. NaV1.6 density within these regions
 increased in cD96V relative to WT. Consistent with NaV1.6 dysregulation by
 D96V-CaM in these regions, we observed increased late NaV activity in
 T-tubules. The resulting late INa promoted aberrant Ca2+ release and
 prolonged APD in myocytes, leading to LQT and ventricular tachycardia (VT)
 in vivo. Cardiac-specific NaV1.6 knockout protected cD96V mice from
 increased T-tubular late NaV activity, and its arrhythmogenic
 consequences. In summary, we demonstrate that D96V-CaM promotes
 arrhythmias by dysregulating LTCC and NaV1.6 within T-tubules and thereby,
 facilitating aberrant Ca2+ release.
description: STORM: Zip file containing single molecule localization data from
 STORM AP and Ca records: Zip file containing action
 potential (AP) and calcium imaging (Ca<sup>2+</sup>)
 records 4,9 ahTTX IC50: Zip file containing patch clamp
 records from dose-response (IC50) experiments for 4,9ah TTX blockade of
 human and mouse Na<sub>V</sub>1.5 and
 Na<sub>V</sub>1.6 AIP AP in cD96V: Zip file
 containing action potential (AP) records from cD96V myocytes incubated
 in Autocamtide-2-related inhibitory peptide, myristoylated (AIP)
 Ca Sparks: Zip file containing records of
 Ca<sup>2+</sup> sparks Cardiac myocytes and
 CHO whole cell D96V-CaM INa: Zip file containing whole cell sodium current
 (I<sub>Na</sub>) records from mouse cardiac myocytes and CHO
 cells dialyzed with WT-CaM and D96V-CaM ECG: Zip file
 containing ECG data Fibrosis: Zip file containing
 fibrosis assessment data ICa: Zip file containing whole
 cell patch clamp records of Ca<sup>2+</sup> current (ICa) in
 cD96V and cD96V x cNaV1.6KO myocytes IPSC INa: Zip file
 containing whole cell patch clamp records of Na<sup>+</sup>
 currents (INa) in human induced pluripotent stem cells derived cardiac
 myocytes (hIPSC-CMs) dialyzed with WT-CaM or D96V-CaM
 ITC: Zip file containing isothermal titration calorimetry (ITC)
 data MRI Data: Zip file containing magnetic resonance
 imaging (MRI) data WB: Zip file containing western blot
 (WB) data Confocal Data: Zip file containing confocal
 microscopy data is split into 9 volumes (001 – 009) Ca
 waves and SR load: Zip file containing calcium imaging data is split into
 4 volumes (001 – 004) Smart patch: Zip file containing
 scanning ion conductance microscopy guided ‘smart’ patch clamp
 data