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EPAC microdomain regulation of Ca2+ handling via cAMP and CaMKII in atrial fibrillation (RP03)
Principal Investigators
Project Summary and Goals
Atrial fibrillation is the most common sustained cardiac arrhythmia and is associated with major alterations in the way heart cells handle calcium, a key ion required for normal contraction and electrical activity. These alterations are driven by abnormal activation of intracellular signaling pathways, including those regulated by cyclic AMP (cAMP) and the protein kinase CaMKII. Recent evidence suggests that cAMP signaling is organized into highly localized microdomains within cardiomyocytes, allowing specific cellular functions to be regulated independently. But what’s about CaMKII, is it also compartmentalized? Or EPAC2, the exchange protein directly activated by cAMP (EPAC) that activates CaMKII?
In preliminary studies, we found increased expression of EPAC2 in atrial tissue from patients with atrial fibrillation. We hypothesize that enhanced EPAC2 signalling promotes abnormal activation of CaMKII, leading to spontaneous calcium release events into cardiomyocytes that contribute to the arrhythmia. Furthermore, changes in the subcellular localization of CaMKII may amplify these pro-arrhythmic effects.
In this project, we will combine complementary expertise in Hamburg and Paris to investigate how EPAC- and CaMKII-dependent microdomains regulate calcium handling in human atrial cardiomyocytes from patients with and without atrial fibrillation.
Aims Addressed by the Doctoral Candidates
- Study how EPAC2 contributes to the subcellular cAMP and CaMKII signals in human atrial myocytes and how this pathway is remodeled in atrial pathophysiology.
- Analyze EPAC2 dependent modulation of Ca2+-handling in human atrial myocytes and how this modulation is altered during atrial fibrillation.
Key Techniques
- Isolation and culture of human cardiomyocytes
- Förster resonance energy transfer (FRET) biosensors
- Patch-clamp
- Confocal calcium imaging
Publications
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Mapping genetic changes in the cAMP-signaling cascade in human atria. Garnier A, Bork NI, Jacquet E, Zipfel S, Muñoz-Guijosa C, Baczkó I, Reichenspurner H, Donzeau-Gouge P, Maier LS, Dobrev D, Girdauskas E, Nikolaev VO, Fischmeister R, Molina CE (2021). J Mol Cell Cardiol. 155:10-20. -
Phosphodiesterase-4 Controls Cyclic AMP/PKA-Dependent Signaling in Human Atrium and Protects against Atrial Fibrillation. Molina CE, Leroy J, Richter W, Xie M, Scheitrum C, Lee I, Maack C, Rucker-Martin C, Verde I, Llach A, Hove-Madsen L, Conti M, Vandecasteele G, Fischmeister R (2012). J Am Coll Cardiol. 59:2182-2190. -
Epac2 mediates cardiac β1-adrenergic-dependent sarcoplasmic reticulum Ca2+ leak and arrhythmia. Pereira L, Cheng H, Lao DH, Na L, van Oort RJ, Brown JH, Wehrens XH, Chen J, Bers DM (2013). Circulation. 127:913-922. -
The cAMP binding protein Epac modulates Ca2+ sparks by a Ca2+/calmodulin kinase signalling pathway in rat cardiac myocytes. Pereira L, Métrich M, Fernández-Velasco M, Lucas A, Leroy J, Perrier R, Morel E, Fischmeister R, Richard S, Bénitah JP, Lezoualc'h F, Gómez AM (2007). J Physiol. 583:685-694.
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Novel Epac fluorescent ligand reveals distinct Epac1 vs. Epac2 distribution and function in cardiomyocytes. Pereira L, Rehmann H, Lao DH, Erickson JR, Bossuyt J, Chen J, Bers DM (2015). Proc Natl Acad Sci USA 112:399-406. -
Abnormal Calcium Handling in Atrial Fibrillation Is Linked to Changes in Cyclic AMP Dependent Signaling. Reinhardt F, Beneke K, Grammatica Pavlidou N, Conradi L, Hove-Madsen L, Molina CE (2021). Cells 10:3042.