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Reperfusion therapy after acute myocardial infarction (AMI) can effectively restore the blood supply and nutritional support of ischemic myocardium and save the dying myocardium. However, myocardial ischaemia‐reperfusion (I/R) injury has become a new threat to reperfusion therapy for AMI. Many long‐chain noncoding RNAs (lncRNAs) are dysregulated by I/R damage. Of these dysregulated lncRNAs, Gpr19 was selected as a potential gene of interest based on its high expression change. We aimed to explore the functional role and molecular mechanism of Gpr19 in I/R injury of AMI. C57BL/6 mice underwent I/R injury as in vivo models. Neonatal rat ventricular cardiomyocytes (NRCMs) exposed to an oxygen glucose deprivation/recovery (OGD/R) system were used as an in vitro model. A TUNEL assay, western blot, and oxidative stress analysis were conducted in this study to determine apoptosis and oxidative stress levels. Our results indicated that inhibition of Gpr19 improves cardiac function and reduces apoptosis and myocardial fibrosis scar formation in vivo. Suppression of Gpr19 attenuates oxidative stress and apoptosis in NRCMs exposed to OGD/R. We further demonstrated that inhibition of Gpr19 decreases oxidative stress and apoptosis in OGD/R‐induced NRCMs by regulating miR‐324‐5p and mitochondrial fission regulator 1 (Mtfr1). We elucidated the functional role and potential molecular mechanism of Gpr19 in I/R injury of AMI, provided a theoretical basis for the importance of Gpr9 in I/R injury, and provided a new perspective for the clinical treatment of I/R injury of AMI.

Efficient and robust single-atom catalysts (SACs) based on cheap and earth-abundant elements are highly desirable for electrochemical reduction of nitrogen to ammonia (NRR) under ambient conditions. Herein, for the first time, a Mn–N–C SAC consisting of isolated manganese atomic sites on ultrathin carbon nanosheets is developed via a template-free folic acid self-assembly strategy. The spontaneous molecular partial dissociation enables a facile fabrication process without being plagued by metal atom aggregation. Thanks to well-exposed atomic Mn active sites anchored on two-dimensional conductive carbon matrix, the catalyst exhibits excellent activity for NRR with high activity and selectivity, achieving a high Faradaic efficiency of 32.02% for ammonia synthesis at  − 0.45 V versus reversible hydrogen electrode. Density functional theory calculations unveil the crucial role of atomic Mn sites in promoting N2 adsorption, activation and selective reduction to NH3 by the distal mechanism. This work provides a simple synthesis process for Mn–N–C SAC and a good platform for understanding the structure-activity relationship of atomic Mn sites. Graphic Abstract

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