Outlining cardiac ion channel protein interactors and their signature in the human electrocardiogram

Abstract

Protein–protein interactions are essential for normal cellular processes and signaling events. Defining these interaction networks is therefore crucial for understanding complex cellular functions and interpretation of disease-associated gene variants. We need to build a comprehensive picture of the interactions, their affinities and interdependencies in the specific organ to decipher hitherto poorly understood signaling mechanisms through ion channels. Here we report the experimental identification of the ensemble of protein interactors for 13 types of ion channels in murine cardiac tissue. Of these, we validated the functional importance of ten interactors on cardiac electrophysiology through genetic knockouts in zebrafish, gene silencing in mice, super-resolution microscopy and patch clamp experiments. Furthermore, we establish a computational framework to reconstruct human cardiomyocyte ion channel networks from deep proteome mapping of human heart tissue and human heart single-cell gene expression data. Finally, we integrate the ion channel interactome with human population genetics data to identify proteins that influence the electrocardiogram (ECG). We demonstrate that the combined channel network is enriched for proteins influencing the ECG, with 44% of the network proteins significantly associated with an ECG phenotype. Altogether, we define interactomes of 13 major cardiac ion channels, contextualize their relevance to human electrophysiology and validate functional roles of ten interactors, including two regulators of the sodium current (epsin-2 and gelsolin). Overall, our data provide a roadmap for our understanding of the molecular machinery that regulates cardiac electrophysiology.

High-Resolution Proteomics Unravel a Native Functional Complex of Cav1.3, SK3, and Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels in Midbrain Dopaminergic Neurons

“…Understanding the role of the ion channel complex in the pathophysiology of neurological disease is still in its infancy and lagging behind the comprehension of cardiac dysfunctions. Recently, Maurya et al [ 99 ] identified protein interactants for 13 types of ion channels and established ion channel networks in murine and human heart tissues. Correlations were found in human population genetics data to specifically identify interacting proteins that influence the electrocardiogram [ 99 ].…”

“…Recently, Maurya et al [ 99 ] identified protein interactants for 13 types of ion channels and established ion channel networks in murine and human heart tissues. Correlations were found in human population genetics data to specifically identify interacting proteins that influence the electrocardiogram [ 99 ]. Nevertheless, in neurons, AMPAR interacting partners regulating the number and function of AMPA receptors at the post-synapse, controlling synaptic strength and plasticity, have been often found in human patients suffering from schizophrenia or autistic spectrum disorders (see [ 100 ] for a review).…”

The proteostasis interactomes of trafficking-deficient variants of the voltage-gated potassium channel KV11.1 associated with long QT syndrome

“…This study is the first to investigate the interactomes of trafficking-deficient K V 11.1 variants and compare them to WT K V 11.1 using AP-MS coupled with TMT labeling. Through this approach, we identified several proteins already known to interact with K V 11.1, such as the E3 ubiquitin ligase ( NEDD4L ), the four-and-a-half LIM domains protein 2 ( FHL2 ), the lectin-based folding chaperone calnexin ( CANX ) , caveolin 1 ( CAV1 ), and the 14-3-3ε protein ( YWHAE ) ( 26 , 27 , 38 , 39 , 40 , 41 ). The truncated variant interaction with 14-3-3ε was reduced compared to either WT or the full-length K V 11.1-G601S variant, consistent with previous work that suggests 14-3-3ε interacts with the C-terminal domain ( 39 ).…”

Developing Cardiac Digital Twins at Scale: Insights from Personalised Myocardial Conduction Velocity

“…This finding reaffirms previous research highlighting age-related changes including both structural changes such as increased LV wall mass 43 , possibly driven by cardiomyocyte hypertrophy and functional changes such as the decline in diastolic function 24,44 . This decline in the CV may be driven by well-established age-related cellular and tissue level remodelling including impaired sodium channel function 44 (potentially though loss-of-function genetic mutations such as SCN5A as identified in previous ECG age-delta GWAS 45 and experimental studies 46 ) and the development of myocardial fibrosis 24,47 . It may also be affected by gap junction decoupling such as connexin 43 downregulation which is a known pathological remodelling in patients with ventricular hypertrophy and ischaemic heart diseases 48 .…”