A novel machine learning-based screening identifies statins as inhibitors of the calcium pump SERCA

Cruz-Cortés, Carlos; Velasco-Saavedra, M Andrés; Gortari, Eli Fernández-de; Guerrero-Serna, Guadalupe; Aguayo‐Ortiz, Rodrigo; Espinoza-Fonseca, L. Michel

doi:10.1016/j.jbc.2023.104681

Cited by 4 publications

References 80 publications

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Mechanisms for cardiac calcium pump activation by its substrate and a synthetic allosteric modulator using fluorescence lifetime imaging

Šeflová,

Cruz-Cortés,

Guerrero-Serna

et al. 2023

PNAS Nexus

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The discovery of allosteric modulators is an emerging paradigm in drug discovery, and signal transduction is a subtle and dynamic process that is challenging to characterize. We developed a time-correlated single photon counting (TCSPC) imaging approach to investigate the structural mechanisms for small-molecule activation of the cardiac sarcoplasmic reticulum Ca2+-ATPase (SERCA2a), a pharmacologically important pump that transports Ca2+ at the expense of ATP hydrolysis. We first tested whether the dissociation of SERCA2a from its regulatory protein phospholamban (PLN) is required for small-molecule activation. We found that CDN1163, a validated SERCA2a activator, does not have significant effects on the stability of the SERCA2a–PLN complex. TCSPC imaging experiments using the non-hydrolyzable ATP analog AMP-PCP showed ATP is an allosteric modulator of SERCA2a, increasing the fraction of catalytically competent structures at physiologically relevant Ca2+ concentrations. Unlike ATP, CDN1163 alone has no significant effects on the Ca2+-dependent shifts in the structural populations of SERCA2a, and it does not increase the pump’s affinity for Ca2+ ions. However, we found that CDN1163 enhances the ATP-mediated modulatory effects to increase the population of catalytically competent SERCA2a structures. Importantly, this structural shift occurs within the physiological window of Ca2+ concentrations at which SERCA2a operates. We demonstrated that ATP is both a substrate and modulator of SERCA2a and showed that CDN1163 and ATP act synergistically to populate SERCA2a structures that are primed for phosphorylation. This study provides novel insights into the structural mechanisms for SERCA2a activation by its substrate and a synthetic allosteric modulator.

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Mechanisms for cardiac calcium pump activation by its substrate and a synthetic allosteric modulator using fluorescence lifetime imaging

Šeflová,

Cruz-Cortés,

Guerrero-Serna

et al. 2023

PNAS Nexus

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Activation mechanism of the cardiac calcium pump by a small-molecule allosteric modulator

Šeflová,

Cruz-Cortés,

Guerrero-Serna

et al. 2023

Preprint

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The discovery of small-molecule allosteric modulators is an emerging paradigm in drug discovery, and signal transduction is a subtle and dynamic process that is challenging to characterize. We developed a time-correlated single photon counting (TCSPC) imaging approach to investigate the activation mechanism of a druggable protein by a small-molecule allosteric modulator. We tested this approach using the cardiac sarcoplasmic reticulum Ca2+-ATPase (SERCA2a), an important pharmacological target that transports Ca2+at the expense of ATP hydrolysis in the heart. We found that CDN1163, a validated SERCA2a activator, does not dissociate the endogenous complex between SERCA2a and its regulator phospholamban (PLN) in the presence of either Ca2+or AMP-PCP, a non-hydrolyzable ATP analog. CDN1163 does not influence SERCA2a’s affinity for Ca2+ions at functionally relevant conditions. Global analysis of the fluorescence lifetimes showed that ATP is both a substrate and a modulator that populates competent SERCA2a conformations. Interestingly, CDN1163 alone does not significantly induce changes in the structural populations of SERCA2a. Instead, CDN1163 potentiates the effects of ATP to further shift the equilibrium toward a competent SERCA2a conformation. Importantly, this population shift occurs at sub-physiological conditions, and within physiological Ca2+concentrations at which SERCA2a operates. We propose an activation mechanism whereby a small-molecule modulator synergizes with ATP to stabilize a conformation of SERCA2a primed for activation. This study demonstrates the power of TCSPC to reveal novel insights into how structural and biochemical states are coupled to allosterically activate a pharmacological target in the heart.

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Paradoxical SERCA dysregulation contributes to atrial fibrillation in a model of diet-induced obesity

Ponce-Balbuena,

Tyrrell,

Cruz-Cortés

et al. 2024

Preprint

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Obesity is a major risk factor for atrial fibrillation (AF) the most common serious cardiac arrhythmia, but the molecular mechanisms underlying diet-induced AF remain unclear. In this study, we subjected mice to a chronic high-fat diet and acute sympathetic activation (‘two-hit’ model) to study the mechanisms by which diet-induced obesity promotes AF. Surface electrocardiography revealed that diet-induced obesity and sympathetic activation synergize during intracardiac tachypacing to induce AF. At the cellular level, diet-induced obesity and acute adrenergic stimulation facilitate the formation of delayed afterdepolarizations in atrial myocytes, implicating altered Ca2+dynamics as the underlying cause of AF. We found that diet-induced obesity does not alter the expression of major Ca2+-handling proteins in atria, including the sarcoplasmic reticulum Ca2+-ATPase (SERCA), a major component of beat-to-beat Ca2+cycling in the heart. Paradoxically, obesity reduces phospholamban phosphorylation, suggesting decreased SERCA activity, yet atrial myocytes from obese mice showed a significantly increased Ca2+transient amplitude and SERCA-mediated Ca2+uptake. Adrenergic stimulation further increases the Ca2+transient amplitude but does not affect Ca2+reuptake in atrial myocytes from obese mice. Transcriptomics analysis showed that a high-fat diet prompts upregulation of neuronatin, a protein that has been implicated in obesity and is known to stimulate SERCA activity. We propose a mechanism in which obesity primes SERCA for paradoxical activation, and adrenergic stimulation facilitates AF conversion through a Ca2+-induced Ca2+release gain in atrial myocytes. Overall, this study links obesity, altered Ca2+signaling, and AF, and targeting this mechanism may prove effective for treating obesity-induced AF.

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A novel machine learning-based screening identifies statins as inhibitors of the calcium pump SERCA

Cited by 4 publications

References 80 publications

Mechanisms for cardiac calcium pump activation by its substrate and a synthetic allosteric modulator using fluorescence lifetime imaging

Mechanisms for cardiac calcium pump activation by its substrate and a synthetic allosteric modulator using fluorescence lifetime imaging

Activation mechanism of the cardiac calcium pump by a small-molecule allosteric modulator

Paradoxical SERCA dysregulation contributes to atrial fibrillation in a model of diet-induced obesity

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