The type 2a sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) plays a central role in the intracellular Ca2+ homeostasis of cardiac myocytes, pumping Ca2+ 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 Ca2+ 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 Ca2+-ATPase and Ca2+ transport activities in cardiac SR vesicles, and on Ca2+ regulation in a HEK293 cell expression system and in mouse ventricular myocytes. We found that compound 1 enhances SERCA2a Ca2+-ATPase and Ca2+ 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 Ca2+ dynamics in HEK293 cells expressing human SERCA2a showed that compound 1 increases endoplasmic reticulum Ca2+ load by enhancing SERCA2a-mediated Ca2+ transport. Analysis of cytosolic Ca2+ dynamics in mouse ventricular myocytes revealed that compound 1 increases the action potential-induced Ca2+ transients and SR Ca2+ load, with negligible effects on L-type Ca2+ channels and Na+/Ca2+ exchanger. However, during adrenergic receptor activation, compound 1 did not further increase Ca2+ transients and SR Ca2+ load, but it decreased the propensity toward Ca2+ waves. Suggestive of concurrent desirable effects of compound 1 on RyR2, [3H]-ryanodine binding to cardiac SR vesicles shows a small decrease in nM Ca2+ and a small increase in μM Ca2+. Accordingly, compound 1 slightly decreased Ca2+ sparks in permeabilized myocytes. Thus, this novel compound shows promising characteristics to improve intracellular Ca2+ dynamics in cardiomyocytes that exhibit reduced SERCA2a Ca2+ uptake, as found in failing hearts.
|Original language||English (US)|
|Number of pages||11|
|State||Published - Jan 17 2023|
Bibliographical noteFunding Information:
This work was supported by the National Institutes of Health Grants R01HL151990 (to A.V.Z.), R01HL139065 (to D.D.T. and R.L.C.), R01HL138539 (to R.L.C.), and R37AG026160 (to D.D.T.). The authors would like to thank Dr. Christopher George (University of Cardiff, UK) for providing the vector encoding the human RyR2. The authors also would like to thank Dr. Masamitsu Iino for donating the R-CEPIA1er vector. R.L.C. and D.D.T. hold equity in, and serve as executive officers for, Photonic Pharma LLC, which had no role in this study. These relationships have been reviewed and managed by the University of Minnesota.
This work was supported by the National Institutes of Health Grants R01HL151990 (to A.V.Z.), R01HL139065 (to D.D.T. and R.L.C.), R01HL138539 (to R.L.C.), and R37AG026160 (to D.D.T.). The authors would like to thank Dr. Christopher George (University of Cardiff, UK) for providing the vector encoding the human RyR2. The authors also would like to thank Dr. Masamitsu Iino for donating the R-CEPIA1er vector.
© 2022 Biophysical Society
PubMed: MeSH publication types
- Journal Article
- Research Support, N.I.H., Extramural