Integrins Increase Sarcoplasmic Reticulum Activity for Excitation-Contraction Coupling in Human Stem Cell-Derived Cardiomyocytes

• Published in: International journal of molecular sciences Vol. 23; no. 18; p. 10940
• Main Authors: Wang, Brian X, Kane, Christopher, Nicastro, Laura, King, Oisín, Kit-Anan, Worrapong, Downing, Barrett, Deidda, Graziano, Couch, Liam S, Pinali, Christian, Mitraki, Anna, MacLeod, Kenneth T, Terracciano, Cesare M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 19-09-2022; MDPI
• Subjects: Action potential; Arginine - metabolism; Aspartic acid; Aspartic Acid - metabolism; Binding; Ca2+ cycling; Caffeine; Caffeine - pharmacology; Calcium (reticular); Calcium - metabolism; Calcium channels; Calcium channels (L-type); Calcium ions; Cardiac muscle; cardiomyocyte; Cardiomyocytes; Congestive heart failure; Coronary artery disease; Cycles; Excitation; Extracellular matrix; Fibronectin; Fibronectins - metabolism; fibrosis; Glass substrates; Glycine; Glycine - metabolism; Heart diseases; Humans; Induced Pluripotent Stem Cells; integrin; Integrins; Integrins - metabolism; Ligands; Microelectrodes; Morphology; Muscle contraction; Muscles; Myocytes, Cardiac - metabolism; Peptides; Pluripotency; Proteins; Ryanodine Receptor Calcium Release Channel - metabolism; Ryanodine receptors; Sarcoplasmic reticulum; Sarcoplasmic Reticulum - metabolism; Scaffolding; stem cell; Stem cells; Structure-function relationships; Ca2+ cycling; stem cell; cardiomyocyte; fibrosis; ryanodine receptor; integrin; sarcoplasmic reticulum
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms231810940

Engagement of the sarcoplasmic reticulum (SR) Ca
stores for excitation-contraction (EC)-coupling is a fundamental feature of cardiac muscle cells. Extracellular matrix (ECM) proteins that form the extracellular scaffolding supporting cardiac contractile activity are thought to play an integral role in the modulation of EC-coupling. At baseline, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) show poor utilisation of SR Ca
stores, leading to inefficient EC-coupling, like developing or human CMs in cardiac diseases such as heart failure. We hypothesised that integrin ligand-receptor interactions between ECM proteins and CMs recruit the SR to Ca
cycling during EC-coupling. hiPSC-CM monolayers were cultured on fibronectin-coated glass before 24 h treatment with fibril-forming peptides containing the integrin-binding tripeptide sequence arginine-glycine-aspartic acid (2 mM). Micropipette application of 40 mM caffeine in standard or Na
/Ca
-free Tyrode's solutions was used to assess the Ca
removal mechanisms. Microelectrode recordings were conducted to analyse action potentials in current-clamp. Confocal images of labelled hiPSC-CMs were analysed to investigate hiPSC-CM morphology and ultrastructural arrangements in Ca
release units. This study demonstrates that peptides containing the integrin-binding sequence arginine-glycine-aspartic acid (1) abbreviate hiPSC-CM Ca
transient and action potential duration, (2) increase co-localisation between L-type Ca
channels and ryanodine receptors involved in EC-coupling, and (3) increase the rate of SR-mediated Ca
cycling. We conclude that integrin-binding peptides induce recruitment of the SR for Ca
cycling in EC-coupling through functional and structural improvements and demonstrate the importance of the ECM in modulating cardiomyocyte function in physiology.