MOG1 rescues defective trafficking of na_v1.5 mutations in brugada syndrome and sick sinus syndrome

Background-Loss-of-function mutations in Na_v1.5 cause sodium channelopathies, including Brugada syndrome, dilated cardiomyopathy, and sick sinus syndrome; however, no effective therapy exists. MOG1 increases plasma membrane (PM) expression of Na_v1.5 and sodium current (I _Na) density, thus we hypothesize that MOG1 can serve as a therapeutic target for sodium channelopathies. Methods and Results-Knockdown of MOG1 expression using small interfering RNAs reduced Na_v1.5 PM expression, decreased I_Na densities by 2-fold in HEK/Na_v1.5 cells and nearly abolished I_Na in mouse cardiomyocytes. MOG1 did not affect Na_v1.5 PM turnover. MOG1 small interfering RNAs caused retention of Na_v1.5 in endoplasmic reticulum, disrupted the distribution of Na_v1.5 into caveolin-3-enriched microdomains, and led to redistribution of Na_v1.5 to noncaveolin-rich domains. MOG1 fully rescued the reduced PM expression and I_Na densities by Na _v1.5 trafficking-defective mutation D1275N associated with sick sinus syndrome/dilated cardiomyopathy/atrial arrhythmias. For Brugada syndrome mutation G1743R, MOG1 restored the impaired PM expression of the mutant protein and restored I_Na in a heterozygous state (mixture of wild type and mutant Na_v1.5) to a full level of a homozygous wild-type state. Conclusions-Use of MOG1 to enhance Na_v1.5 trafficking to PM may be a potential personalized therapeutic approach for some patients with Brugada syndrome, dilated cardiomyopathy, and sick sinus syndrome in the future.