14-3-3 promotes sarcolemmal expression of cardiac CaV1.2 and nucleates isoproterenol-triggered channel super-clustering

Spooner, H. C.; Costa, A. D.; Hernandez Gonzalez, A.; Ibrahimkhail, H.; Yarov-Yarovoy, V.; Horne, M.; Dickson, E. J.; Dixon, R. E.

doi:10.1101/2024.08.16.607987

bioRxiv · 10.1101/2024.08.16.607987

14-3-3 promotes sarcolemmal expression of cardiac CaV1.2 and nucleates isoproterenol-triggered channel super-clustering

Spooner, H. C.·Costa, A. D.·Hernandez Gonzalez, A.·Ibrahimkhail, H.·Yarov-Yarovoy, V.·Horne, M.·Dickson, E. J.·Dixon, R. E.

View original source ↗Export metadata ↓

Abstract

The L-type Ca2+ channel (CaV1.2) is essential for cardiac excitation-contraction coupling. To contribute to the inward Ca2+ flux that drives Ca2+-induced-Ca2+-release, CaV1.2 channels must be expressed on the sarcolemma; thus the regulatory mechanisms that tune CaV1.2 expression to meet contractile demand are an emerging area of research. A ubiquitously expressed protein called 14-3-3 has been proposed to affect Ca2+ channel trafficking in non-myocytes, however whether 14-3-3 has similar effects on CaV1.2 in cardiomyocytes is unknown. 14-3-3 preferentially binds phospho-serine/threonine residues to affect many cellular processes and is known to regulate cardiac ion channels including NaV1.5 and hERG. Altered 14-3-3 expression and function have been implicated in cardiac pathologies including hypertrophy. Accordingly, we tested the hypothesis that 14-3-3 interacts with CaV1.2 in a phosphorylation-dependent manner and regulates cardiac CaV1.2 trafficking and recycling. Confocal imaging, proximity ligation assays, super-resolution imaging, and co-immunoprecipitation revealed a population of 14-3-3 colocalized and closely associated with CaV1.2. The degree of 14-3-3/CaV1.2 colocalization increased upon stimulation of {beta}-adrenergic receptors with isoproterenol. Notably, only the 14-3-3-associated CaV1.2 population displayed increased cluster size with isoproterenol, revealing a role for 14-3-3 as a nucleation factor that directs CaV1.2 super-clustering. 14-3-3 overexpression increased basal CaV1.2 cluster size and Ca2+ currents in ventricular myocytes, with maintained channel responsivity to isoproterenol. In contrast, isoproterenol-stimulated augmentation of sarcolemmal CaV1.2 expression and currents in ventricular myocytes were abrogated by 14-3-3 inhibition. These data support a model where 14-3-3 interacts with CaV1.2 in a phosphorylation-dependent manner to promote enhanced trafficking/recycling, clustering, and activity during {beta}-adrenergic stimulation. Significance StatementThe L-type Ca2+ channel, CaV1.2, plays an essential role in excitation-contraction coupling in the heart and in part regulates the overall strength of contraction during basal and fight- or-flight {beta}-adrenergic signaling conditions. Proteins that modulate the trafficking and/or activity of CaV1.2 are interesting both from a physiological and pathological perspective, since alterations in CaV1.2 can impact action potential duration and cause arrythmias. A small protein called 14-3-3 regulates other ion channels in the heart and other Ca2+ channels, but how it may interact with CaV1.2 in the heart has never been studied. Examining factors that affect CaV1.2 at rest and during {beta}-adrenergic stimulation is crucial for our ability to understand and treat disease and aging conditions where these pathways are altered.

Source connections

Published article ↗

Explore related subjects

physiology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Spooner, H. C., Costa, A. D., Hernandez Gonzalez, A., Ibrahimkhail, H., Yarov-Yarovoy, V., Horne, M., Dickson, E. J., Dixon, R. E.. 2024-08-19. 14-3-3 promotes sarcolemmal expression of cardiac CaV1.2 and nucleates isoproterenol-triggered channel super-clustering. https://doi.org/10.1101/2024.08.16.607987

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Thoracoabdominal pressure transmission during prone and supine cardiopulmonary resuscitation in fresh-frozen human cadavers

Background: Prone cardiopulmonary resuscitation (CPR) may be necessary when turning a prone patient supine would delay chest compressions. Although prone compressions can generate arterial pressures comparable with or greater than supine CPR, the pathway of pressure transmission is uncertain. We examined synchronized intrathoracic, intra-abdominal, and central arterial pressures in both supine and prone positions. Methods: Two thawed fresh-frozen adult cadavers underwent three, 2-minute mechanical CPR trials per position in a counterbalanced crossover sequence. Solid-state catheters recorded pleural, peritoneal, and central arterial pressures simultaneously. Trial-level outcomes included peak pressure, mean pressure, pressure-time area, and the mean peritoneal-to-pleural pressure gradient. Exploratory fixed-effects models included position, cadaver, and their interaction. Results: Prone CPR increased peak intrathoracic pressure by 7.04 mmHg, peak intra-abdominal pressure by 21.69 mmHg, and peak arterial pressure by 15.40 mmHg. Mean intra-abdominal and arterial pressures increased by 16.22 and 9.90 mmHg, respectively. The mean peritoneal-to-pleural gradient reversed direction from -8.46 mmHg supine to 4.85 mmHg prone. Intrathoracic pressure-time area increased 3.4-fold, from 1.62 to 5.46 mmHg{middle dot}s, and arterial pressure-time area increased 2.2-fold, from 2.96 to 6.42 mmHg{middle dot}s. Conclusions: Compared to supine, prone mechanical CPR generated higher arterial pressures and reversed the pressure relationship across the thoracoabdominal boundary in both cadavers. Higher abdominal pressure coincided with a larger intrathoracic pressure-time area, a pattern compatible with reduced caudal pressure dissipation.

physiology↗

bioRxiv2026

Hypothalamic Farnesoid X Receptor deficiency alters energy balance by modulating hepatic glucose production and adipose tissue metabolism through central insulin signaling.

Objectives: The bile acid nuclear receptor Farnesoid X Receptor (FXR, NR1H4) is a major regulator of metabolism and energy homeostasis in peripheral organs. It modulates bile acid, glucose, and lipid metabolism, as well as fat mass and body weight. However, FXR is also expressed in the brain, particularly in the hypothalamus, a key center for the regulation of energy homeostasis. Although one study has demonstrated a role for brain FXR activation in energy balance, its specific hypothalamic role is still unknown. Here, we examined the role of FXR in the mediobasal hypothalamus in the regulation of energy balance. Methods: We used a genetic approach combined with metabolic phenotyping to determine the effect of FXR invalidation in the mediobasal hypothalamus on metabolic parameters involved in the central regulation of energy homeostasis. Results: Our results demonstrate that hypothalamic FXR deficiency induces a positive energy balance, resulting in a reduction in energy expenditure due to alterations in glucose metabolism accompanied by structural changes in white adipose tissues. Conclusion: This study uncovers a previously unrecognized role for hypothalamic FXR in the central homeostatic control of energy balance, providing new insights into its contribution to peripheral glucose metabolism and adipose tissue structural remodeling.

physiology↗

bioRxiv2026

Rad and Phospholamban are Key Drivers of the Ventricular Adrenergic Response and Stress-Induced Arrhythmia

The adrenergic response is a fundamental mechanism that regulates heart rate (chronotropy), cardiac contractility (inotropy) and relaxation (lusitropy). Adrenergic stress is also a recognized trigger of arrhythmia in disease. Yet, our understanding of the underlying molecular basis remains incomplete. Protein kinase A (PKA) and the calcium/calmodulin-dependent kinase II (CaMKII) phosphorylate multiple targets proposed to participate in the adrenergic response, including the GTP-binding protein Rad, phospholamban (PLB) and ryanodine receptor 2 (RyR2). Here we demonstrate that phosphorylation of both Rad and PLB is necessary for inotropy and lusitropy. We show that changes in cardiac contractility and relaxation are primarily dependent on intracellular calcium handling. Finally, we report that Rad and PLB control stress-induced arrhythmogenesis, despite the phosphorylation of other pro-arrhythmic targets. We have identified the essential molecular components of the adrenergic response, resolving a long-standing debate in cardiac excitation-contraction coupling and refining current models of sympathetic regulation in health and disease.

physiology↗