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

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

doi:10.3389/fcell.2021.724778

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

Front Cell Dev Biol. 2022 Jan 3:9:724778. doi: 10.3389/fcell.2021.724778. eCollection 2021.

Authors

Yiliam Cruz-Garcia¹, Katalin Barkovits^{2

3}, Michael Kohlhaas⁴, Simone Pickel¹, Michelle Gulentz⁴, Cornelia Heindl¹, Kathy Pfeiffer^{2

3}, Petra Eder-Negrin⁴, Christoph Maack⁴, Katrin Marcus^{2

3}, Michaela Kuhn^{1

4}, Erick Miranda-Laferte^{1

5}

Affiliations

¹ Institute of Physiology, University of Würzburg, Würzburg, Germany.
² Medizinisches Proteom-Center, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.
³ Medical Proteome Analysis, Center for Proteindiagnostics (PRODI), Ruhr-University Bochum, Bochum, Germany.
⁴ Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany.
⁵ Institut für Biologische Informationsprozesse, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany.

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 Ca_vα₁, Ca_vβ, Ca_vα₂δ and Ca_vγ subunits. Here, using ascorbate peroxidase (APEX2)-mediated proximity labeling and quantitative proteomics, we identified 61 proteins in the nanoenvironments of Ca_vβ₂ in cardiomyocytes. These proteins are involved in diverse cellular functions such as cellular trafficking, cardiac contraction, sarcomere organization and excitation-contraction coupling. Moreover, pull-down assays and co-immunoprecipitation analyses revealed that Ca_vβ₂ 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 Ca_vβ₂ and is necessary for an effective pacing frequency-dependent increase of the Ca²⁺-induced Ca²⁺ release mechanism in cardiomyocytes.

Keywords: APEX-mediated proximity labeling; calcium-induced calcium release; cardiomyocytes; protein-protein interaction; ryanodine receptor; β-subunit voltage-gated calcium channels.