Super-resolution imaging reveals that loss of the C-terminus of connexin43 limits microtubule plus-end capture and NaV1.5 localization at the intercalated disc

Abstract

NaV1.5 and EB1 localization at the cell end is Cx43-dependent. Cx43 is part of a molecular complex that determines capture of the microtubule plus-end at the ID, facilitating cargo delivery. These observations link excitability and electrical coupling through a common molecular mechanism.

Sodium Channel Remodeling in Subcellular Microdomains of Murine Failing Cardiomyocytes

“…Na V 1.5 is trafficked to and delivered into the cell membrane by the microtubule network. Specific sites of delivery are determined by macromolecular complexes composed of anchoring and microtubule capture proteins 19, 24. In TAC hearts, increased protein expression levels of the microtubule protein α‐tubulin and plus‐end microtubule capture protein EB1 were observed, indicating a denser microtubule network and a potential increase in microtubule capture sites at the cell membrane (Figure 8A and 8B).…”

“…To this end, we used superresolution localization microscopy (STORM) to resolve the molecular organization of Na V 1.5 in fixed cardiomyocytes isolated from Sham and TAC ventricles, with a lateral resolution of 20 nm 19, 24. No differences in Scn5a mRNA levels or total Na V 1.5 protein levels were observed between Sham and TAC ventricular tissue (Figure 9A through 9C).…”

“…Smaller cluster size, yet unaltered cluster density, in TAC compared with Sham suggests a redirection and redistribution of channels to the newly formed sarcomeres at the LM in TAC cardiomyocytes. Several studies have previously shown that Nav1.5 channels are delivered to their final destination on the membrane through the microtubule network 19, 35. Although microtubule network density was increased in TAC cardiomyocytes, the observed increased detyrosinated tubulin (ie, Glu‐tubulin) levels indicate that the microtubule network is less dynamic25 and, thus, potentially less efficient 36, 37, 38.…”

“…Superresolution microscopy was conducted in a custom‐built system, based on simultaneous 2‐color direct stochastic optical reconstruction microscopy (STORM). Detailed experimental methods are provided in previous publications 19, 20. Cluster analysis was automated for standardization, following criteria detailed by Agullo‐Pascual et al 19.…”

Myocardial expression profiles of candidate molecules in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia compared to those with dilated cardiomyopathy and healthy controls

“…6,7 Recent studies have shown that these intercellular formations may also play a role in signal transduction, apoptosis, and adipogenesis. 8 Early histology and electron microscopy studies revealed that the fibrofatty replacement of the right ventricular myocardium is accompanied by inflammation and apoptosis. 9 Desmosomal mutations may lead to altered cellular distribution of desmosomes, as well as increased apoptosis.…”