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Elucidating differential regulation of the cardiac sodium channel Nav1.5 by super-resolution microscopy

Applicant Vermij Sarah Helena
Number 172237
Funding scheme Doc.Mobility
Research institution New York University School of Medicine Sponsored Programs Administration
Institution of higher education Institution abroad - IACH
Main discipline Molecular Biology
Start/End 01.02.2017 - 31.08.2017
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All Disciplines (2)

Discipline
Molecular Biology
Cellular Biology, Cytology

Keywords (6)

ion channels; super-resolution microscopy; Nav1.5; intercalated disc; T tubules; cardiac arrhythmia

Lay Summary (German)

Lead
Verschiedene Herzrhythmuserkrankungen sind auf Mutationen in Nav1.5 zurückzuführen. Es ist jedoch unbekannt, wie Mutationen auf verschiedenen Loci eines Gens so viele Erkrankungen verursachen können.
Lay summary

Elucidating differential regulation of the cardiac sodium channel Nav1.5 by super-resolution microscopy

Inhalt und Ziele des Forschungsprojekts
Nav1.5 ist ein Ionenkanal in Herzmuskelzellen. Zusammen mit anderen Ionenkänalen, wird ein Signal generiert, das die Herzmuskelzellen beauftragt, sich zusammenzuziehen. Die Funktion von Nav1.5 hängt von der präzisen Lokalisierung in der Zelle ab, sowie von Proteinen, die Nav1.5 binden.

Das erste Ziel des Projekts ist zu zeigen, wo Nav1.5 in den Zellen lokalisiert wird: erstens, im Glanzstreifen, welche die Herzmuskelzellen miteinander verbinden; zweitens, in der Lateralmembran; und drittens, in den T-Tubuli, welche Einstülpungen der Lateralmembran sind.

Das zweite Ziel ist herauszufinden, wo die interagierenden Proteine Nav1.5 binden. Bestimmte Proteine könnten nur in einem bestimmten Lokation vorkommen.

Das dritte Ziel ist, Veränderungen in der Lokalisierung von Nav1.5 und interagierenden Proteine in verschiedenen Mausmodellen zu untersuchen. Diese Modelle repräsentieren Mutationen, die in Patienten mit Herzrhythmuserkrankungen identifiziert worden sind. Um das zerstörte elektrische Verhalten von dieser Mutationen zu erklären, müssen wir aufklären, wie sich das Molekularpuzzle in den Modellen ändert.

Diese Fragen werden adressiert mit dem Super-resolution Mikroskop in Professor Mario Delmar’s Labor an der New York University, USA. Dieses Mikroskop hat eine Auflösung von 20 Nanometer, und ermöglicht uns fast, individuelle Proteine sichtbar zu machen.

Wissenschaftlicher und gesellschafticher Kontext des Forschungsprojekts
Das Projekt ist stark von menschlichen Erkrankungen inspiriert. Wenn wir besser verstehen, wie Mutationen in einem Gene so viele verschiedene Effekte haben, ist eine Patientenspezifische Behandlung einen Schritt näher gebracht.

Direct link to Lay Summary Last update: 15.12.2016

Responsible applicant and co-applicants

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Thesis Defense Sarah Vermij Individual talk Characterizing Nav1.5 expression, organization, and electrical behavior in cardiomyocyte domains 30.08.2019 Bern, Switzerland Vermij Sarah Helena;
Computational tools to address the roles of cardiac ion channels: insights from the Bernese community Talk given at a conference Passive and active electrical properties of T-tubules 03.07.2019 Bern, Switzerland Vermij Sarah Helena;
Ephaptic Coupling Conference Talk given at a conference Nanoscale excitement: Characterizing the expression of the cardiac sodium channel Nav1.5 in cardiomyocyte domains 05.05.2019 Roanoke, Virginia, United States of America Vermij Sarah Helena;
LS2 Cardiov ascular Research Meeting Poster Defining nanoscale sub-populations of the cardiac sodium channel Nav1.5 in cardiomyocytes 14.03.2019 Fribourg, Switzerland Vermij Sarah Helena;
GCB Symposium 2019 Poster Defining nanoscale sub-populations of the cardiac sodium channel Nav1.5 in cardiomyocytes 31.01.2019 Bern, Switzerland Vermij Sarah Helena;
Life Sciences PostDoc Day 2018 Poster Nanoscale expression of the cardiac sodium channel Nav1.5 in the lateral membrane and T-tubules of murine cardiomyocytes 14.09.2018 Zürich, Switzerland Vermij Sarah Helena;
9th Ascona International Workshop on Cardiomyocyte Biology Poster Nanoscale expression of the cardiac sodium channel Nav1.5 in the lateral membrane and T-tubules of murine cardiomyocytes 22.04.2018 Ascona, Switzerland Vermij Sarah Helena;


Associated projects

Number Title Start Funding scheme
165741 Multiple Nav1.5 Pools in Cardiac Cells: Molecular Determinants and Functional Roles 01.04.2016 Project funding

Abstract

To understand how mutations in SCN5A, encoding the cardiac sodium channel Nav1.5, cause a broad range of diseases, elucidating the subcellular differentiation of Nav1.5 may be a crucial step. This functional differentiation is a relatively new concept. Nav1.5 occurs at least in the intercalated disc (ID) and lateral membrane (LM) of cardiomyocytes, but our data strongly suggest a third pool in the T-tubules (TT). Moreover, how the distribution of proteins that interact with and regulate Nav1.5 differ between pools remains unknown. This project will address these questions with direct stochastical optical reconstruction microscopy (dSTORM), which resolution of 20 nm allows us to image proteins almost individually. We will investigate firstly the TT pool of Nav1.5 by co-localizing Nav1.5 with TT markers Cav1.2 and Bin1. Secondly, the distribution of interacting proteins of the LM and TT pool will be addressed, since the ID pool is already well-characterized. C-terminal binding partners of Nav1.5 have our special attention, including CASK, SAP97, a1-syntrophin and dystrophin. Most of these proteins are known to bind LM Nav1.5, but partners of TT Nav1.5 remain unknown. Thirdly, we will investigate how Nav1.5 cluster size and their complexes differ in the following mouse models: cardiac-specific CASK KO mice show an increase in sodium current (INa), possibly because CASK may limit Nav1.5 clusters size, whereas cardiac-specific SAP97 KO mice have normal INa, and syntrophin KO mice have decreased INa. DeltaSIV KI mice, which Nav1.5 misses the last three C-terminal amino acids, loose the LM Nav1.5 pool but may have a larger TT pool. We may explain the changes in INa in those models by changes in the Nav1.5 complexes.Showing the presence of a TT pool of Nav1.5 would already open up a new field of research on the function of this TT pool. Moreover, this project will increase the understanding of the variety of Nav1.5-associated protein complexes in different mouse models. This will bring us a step closer towards understanding how different SCN5A mutations may affect pools and interacting proteins of Nav1.5 differently, which could explain the broad range in SCN5A-related diseases.
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