AUTHOR=Cruz-Garcia Yiliam , Barkovits Katalin , Kohlhaas Michael , Pickel Simone , Gulentz Michelle , Heindl Cornelia , Pfeiffer Kathy , Eder-Negrin Petra , Maack Christoph , Marcus Katrin , Kuhn Michaela , Miranda-Laferte Erick 

TITLE=Nanoenviroments of the β-Subunit of L-Type Voltage-Gated Calcium Channels in Adult Cardiomyocytes

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=Volume 9 - 2021

YEAR=2022

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2021.724778

DOI=10.3389/fcell.2021.724778

ISSN=2296-634X

ABSTRACT=In cardiomyocytes, Ca2+ influx through L-type voltage-gated calcium channels (LTCCs) following membrane depolarization regulates crucial Ca2+-dependent processes including duration and amplitude of the action potentials and excitation-contraction coupling. LTCCs are heteromultimeric proteins composed of the Cavα1, Cavβ, Cavα2δ and Cavγ subunits. Here, using ascorbate peroxidase (APEX2)-mediated proximity labeling and quantitative proteomics, we identified 61 proteins in the nano-environments of Cavβ2 in cardiomyocytes. These proteins are involved in diverse cellular functions such as cellular trafficking, muscular contraction, sarcomere organization and excitation-contraction coupling. Moreover, pull-down assays and co-immunoprecipitation analyses revealed that Cavβ2 interacts with the ryanodine receptor 2 (RyR2) in adult cardiomyocytes, probably coupling LTCCs and the RyR2 into a supramolecular complex at the dyads. This interaction is mediated by the Src-homology 3 domain of Cavβ2 and is necessary for an effective pacing frequency‐dependent increase of the Ca2+-induced Ca2+ release mechanism in cardiomyocytes.