• Le 25 June 2021
    En visio
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  • 11h30

Targeting the microtubule (+)-end tracking EB1-CLASP2 protein complex modulates NaV1.5 preferentially at the intercalated discs of cardiomyocytes

Targeting the microtubule (+)-end tracking EB1-CLASP2 protein complex modulates NaV1.5 preferentially at the intercalated discs of cardiomyocytes

Vincent PORTERO, PhD invited by Richard Redon (Eq I)

Post-doctoral researcher,Hart Long center, Laboratory of experimental cardiology, LUMC Leiden, The Netherlands



Rationale: Loss-of-function of the cardiac sodium channel NaV1.5 causes conduction slowing and arrhythmias. NaV1.5 is differentially distributed within subcellular domains of cardiomyocytes, with sodium current (INa) being enriched at the intercalated discs (ID). Various pathophysiological conditions associated with lethal arrhythmias display ID-specific INa reduction, but the mechanisms underlying microdomain-specific targeting of NaV1.5 remain largely unknown. Objective: To investigate the role of the microtubule (MT) plus-end tracking proteins end binding protein 1 (EB1) and CLIP-associated protein 2 (CLASP2) in mediating NaV1.5 trafficking and subcellular distribution in cardiomyocytes.

Methods and Results: EB1 overexpression in human induced pluripotent stem cell-derived cardiomyocytes (hiPSCCMs) resulted in enhanced whole-cell INa, increased action potential (AP) upstroke velocity (Vmax), and enhanced NaV1.5 localization at the plasma membrane as detected by multi-color stochastic optical reconstruction microscopy (STORM). Fluorescence recovery after photobleaching (FRAP) experiments in HEK293A cells demonstrated that EB1 overexpression promoted NaV1.5 forward trafficking. Knockout of MAPRE1 in hiPSC-CMs led to reduced whole-cell INa, decreased Vmax and AP duration (APD) prolongation. Similarly, acute knockout of the MAPRE1 homolog in zebrafish (mapre1b) resulted in decreased ventricular conduction velocity and Vmax as well as increased APD. STORM imaging and macropatch INa measurements showed that subacute treatment (2-3 hours) with SB216763 (SB2), a GSK3β inhibitor known to modulate CLASP2-EB1 interaction, reduced GSK3β localization and increased NaV1.5 and INa preferentially at the ID region of wild type murine ventricular cardiomyocytes. By contrast, SB2 did not affect whole cell INa or NaV1.5 localization in cardiomyocytes from Clasp2-deficient mice, uncovering the crucial role of CLASP2 in SB2-mediated modulation of NaV1.5 at the ID.

Conclusions: Our findings demonstrate the modulatory effect of the MT plus-end tracking protein EB1 on NaV1.5 trafficking and function, and identify the EB1-CLASP2 complex as a target for preferential modulation of INa within the ID region of cardiomyocytes.


Vincent Portero is specialized in cardiac genetics and electrophysiology.

From a biomedical background, Vincent started his PhD in 2010 in l’Institut du Thorax in Nantes, France. Supervised by both Pr. Redon and Pr. Charpentier, Vincent performed both genetics and molecular / electrophysiological experiments aiming at unraveling new genes and pathways involved in sudden cardiac death. He was involved in several projects using various genetics approaches such as GWAS, burden test and familial approaches using next generation sequencing techniques. He obtained his doctor title in 2013 from the Nantes university (France).

He then joined the Department of Experimental Cardiology at the Academic Medical Center in Amsterdam (Dr. Remme’s group). During this period, he used integrative genomic approaches, molecular techniques, pharmacological interventions in hiPSC-derived cardiomyocyte disease models. Moreover, he also further strengthened his skills and knowledge regarding both cellular and animal electrophysiology. During his six years post-doctoral position, Vincent obtained several personal subsidies to finance his projects and also participated in PhD student supervision.

In December 2020,Vincent joined the Laboratory of Experimental Cardiology in the Leiden University Medical Center (Leiden, The Netherlands). With Dr. Pijnappels and Dr. De Vries, he aims to further decipher cardiac arrhythmia mechanisms and to explore new avenues to counter their occurrence.