Abstract
Excitation-contraction coupling (ECC) in the cardiac myocyte is mediated by a number of highly integrated mechanisms of intracellular Ca2+ transport. Voltage- and Ca2+-dependent L-type Ca2+ channels (LCCs) allow for Ca2+ entry into the myocyte, which then binds to nearby ryanodine receptors (RyRs) and triggers Ca2+ release from the sarcoplasmic reticulum in a process known as Ca2+-induced Ca2+ release. The highly coordinated Ca2+-mediated interaction between LCCs and RyRs is further regulated by the cardiac isoform of the Ca2+/calmodulin-dependent protein kinase (CaMKII). Because CaMKII targets and modulates the function of many ECC proteins, elucidation of its role in ECC and integrative cellular function is challenging and much insight has been gained through the use of detailed computational models. Multiscale models that can both reconstruct the detailed nature of local signaling events within the cardiac dyad and predict their functional consequences at the level of the whole cell have played an important role in advancing our understanding of CaMKII function in ECC. Here, we review experimentally based models of CaMKII function with a focus on LCC and RyR regulation, and the mechanistic insights that have been gained through their application.
Highlights
Cardiac electrophysiology is a discipline with a rich and deep history dating back more than a half-century
This review focuses on the role of experimentally based models of CaMKII function with a focus on L-type Ca2+ channel (LCC) and ryanodine receptor (RyR) regulation, and the mechanistic insights that have been gained through their application
Integrative modeling of cardiac excitation-contraction coupling (ECC), cell signaling, and myocyte physiology has played a critical role in revealing mechanistic insights across a range of biological scales
Summary
Cardiac electrophysiology is a discipline with a rich and deep history dating back more than a half-century. Koivumaki et al (2009) built a model of the murine cardiac myocyte to analyze genetically engineered heart models in which CaMKIImediated phosphorylation of LCCs is disrupted or CaMKII is overexpressed They demonstrated how these genetic manipulations lead to the observed experimental phenotypes as a result of autoregulatory mechanisms that are inherent in intracellular Ca2+ cycling (e.g., steady-state regulation of SR content via Ca2+ release dependent inactivation of LCCs), and that disruption of the regulatory system itself (e.g., via CaMKII overexpression) leads to the most aberrant physiological phenotypes.
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