New N-aryl-N-alkyl-thiophene-2-carboxamide compound enhances intracellular Ca dynamics by increasing SERCA2a Ca pumping. Journal Article

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Authors: Nikolaienko, R; Bovo, E; Yuen, SL; Treinen, LM; Berg, K; Aldrich, CC; Thomas, DD; Cornea, RL; Zima, AV
Article Title: New N-aryl-N-alkyl-thiophene-2-carboxamide compound enhances intracellular Ca dynamics by increasing SERCA2a Ca pumping.
Abstract: The type 2a sarco/endoplasmic reticulum Ca-ATPase (SERCA2a) plays a central role in the intracellular Ca homeostasis of cardiac myocytes, pumping Ca from the cytoplasm into the sarcoplasmic reticulum (SR) lumen to maintain relaxation (diastole) and prepare for contraction (systole). Diminished SERCA2a function has been reported in several pathological conditions, including heart failure. Therefore, development of new drugs that improve SERCA2a Ca transport is of great clinical significance. In this study, we characterized the effect of a recently identified N-aryl-N-alkyl-thiophene-2-carboxamide (or compound 1) on SERCA2a Ca-ATPase and Ca transport activities in cardiac SR vesicles, and on Ca regulation in a HEK293 cell expression system and in mouse ventricular myocytes. We found that compound 1 enhances SERCA2a Ca-ATPase and Ca transport in SR vesicles. Fluorescence lifetime measurements of fluorescence resonance energy transfer between SERCA2a and phospholamban indicated that compound 1 interacts with the SERCA-phospholamban complex. Measurement of endoplasmic reticulum Ca dynamics in HEK293 cells expressing human SERCA2a showed that compound 1 increases endoplasmic reticulum Ca load by enhancing SERCA2a-mediated Ca transport. Analysis of cytosolic Ca dynamics in mouse ventricular myocytes revealed that compound 1 increases the action potential-induced Ca transients and SR Ca load, with negligible effects on L-type Ca channels and Na/Ca exchanger. However, during adrenergic receptor activation, compound 1 did not further increase Ca transients and SR Ca load, but it decreased the propensity toward Ca waves. Suggestive of concurrent desirable effects of compound 1 on RyR2, [H]-ryanodine binding to cardiac SR vesicles shows a small decrease in nM Ca and a small increase in μM Ca. Accordingly, compound 1 slightly decreased Ca sparks in permeabilized myocytes. Thus, this novel compound shows promising characteristics to improve intracellular Ca dynamics in cardiomyocytes that exhibit reduced SERCA2a Ca uptake, as found in failing hearts.
Journal Title: Biophysical journal
ISSN: 1542-0086; 0006-3495
Publisher: Unknown  
Date Published: 2022