Phosphorylation of SERCA2 at the heart of cardioprotection in human-derived cardiomyocytes

• Published in: Archives of cardiovascular diseases 2024-06, Vol.117 (6-7), p.S182-S182
• Main Authors: Boulogne, Laura, Dargar, Tanushri, Brun, Camille, Leon, Christelle, Chouabe, Christophe, Thibault, Hélène, Bidaux, Gabriel, Sebbag, Laurent, Gache, Vincent, Gomez, Ludovic
• Format: Article
• Language: English
• ISSN: 1875-2136; 1875-2128
• DOI: 10.1016/j.acvd.2024.05.043

Despite promising preclinical results targeting sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA2), clinical trials application remains limited, highlighting the urgency to develop suitable model reflecting clinical physiopathology. Recently, we discovered a new regulatory mechanism of SERCA2 based on serine 663-phosphorylation involved as a key regulator of Ca2+ homeostasis in several cell types (HEK, MEF and isolated mice cardiomyocytes). To assess translational potential, we developed a human-induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM) model focused on modulation of SERCA2 activity. hiPSC-derived cardiomyocytes were infected (6days, MOI 200 000) with the AAV9-Serca [WT], the AAV9-Serca2[S663A] phosphoresistant or the AAV9-Serca2[S663E] phosphomimetic mutants. For [Ca2+]ERexperiments, basal and refilling slope were measured in hiPSC-CM using D4ER Ca2+ probe. Cytosolic Ca2+ imaging was investigated using Fura2 probe (2μM). Cell viability was evaluated after 5h hypoxia (1%O2) and 5h reoxygenation (H/R). In opposite to SERCA2[S663E] cells, the evaluation of SERCA2 activity revealed that SERCA2[S663A] hiPSC-CM displayed significantly increased ER Ca2+ refilling rate (+56%) and ER Ca2+ content (+66%) versus SERCA2[WT]. Interestingly, SERCA2[S663A] displayed a significant decreased cell death after H/R stress compared to SERCA2[WT]. Although, measuring of cytosolic Ca2+ transients in beating control hiPSC-CMs, there were no changes (peak amplitude 0.08μm, area under curve 0.04μm2) in all mutants due to ineffective infection. Our results provide an essential regulatory mechanism of Ca2+ homeostasis and cell death, based on the phosphorylation state of SERCA2 in human cell types, notably hiPSC-CM. Although still requiring some adjustments, hiPSC-CM appear to be an essential model for translational research in the field of heart disease.