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Accumulating evidence has reported the role of microRNA-21-3p (miR-21-3p) in sepsis, and our objective was to discuss the effect of the miR-21-3p/regulator of calcineurin 1 (Rcan1) axis on cardiomyocyte apoptosis of septic rats. miR-21-3p and Rcan1 expression in myocardial tissues of lipopolysaccharide (LPS)-treated rats and LPS-treated H9c2 cardiomyocytes was determined. The influences of downregulating miR-21-3p or upregulating Rcan1 in cardiomyocyte apoptosis of LPS-treated rats and LPS-treated H9c2 cardiomyocytes were then evaluated. The target relation between Rcan1 and miR-21-3p was verified. It was observed that miR-21-3p was elevated and Rcan1 was reduced in LPS-treated rats and LPS-treated H9c2 cardiomyocytes. Downregulating miR-21-3p or upregulating Rcan1 could suppress cardiomyocyte apoptosis of LPS-treated rats and LPS-treated H9c2 cardiomyocytes. Based on the dual-luciferase activity assay, miR-21-3p was directly targeted Rcan1 in H9c2 cardiomyocytes. In the rescue experiment, the LPS+miR-21-3p inhibitor+si-Rcan1 group enhanced the apoptosis of H9c2 cardiomyocytes in comparison to the LPS+miR-21-3p inhibitor+si-NC group. Together, our findings identify that the miR-21-3p/Rcan1 axis may affect apoptosis of cardiomyocytes in sepsis, which provides a new idea for understanding the potential mechanism of sepsis.

MicroRNAs (miRNAs) play crucial roles in regulating various biological processes and are considered promising biomarkers for clinical diagnosis and therapy of acute pancreatitis. Herein, we present a duplex-specific nuclease (DSN enzyme) and DNAzyme-assisted fluorescent miRNA detections assay that can provide improved detection specificity due to a design of dual-target recognition and a comparable sensitivity. The dual-target recognitions are composed of (i) miRNA unfold hairpin structure toehold to form DNA-RNA duplex, among which the DNA section will be digested by DSN enzyme, releasing miRNA to participant in a next recycle. (ii) After DNAzyme-based nicking site formation in loop section of molecular beacon (MB), miRNA can bind with the loop section of MB and gradually unfold MB probe, generating fluorescence signals. With this general principle, distinct discrimination capability towards even one base pair mismatch of homogenous miRNA is obtained, showing a promising prospect in clinical diagnosis and therapy of acute pancreatitis., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Small extracellular vesicles (sEVs) have been reported to play important roles in cell-to-cell communication and are promising biomarkers for the early diagnosis of infections. Therefore, it is in high demand to develop a method that can integrate easy-to-operate sEV isolation and sensitive quantification. We herein propose a novel detection scaffold for sEV isolation via low-speed centrifugation and the quantification of sEVs through DNAzyme-based signal amplification. The detection scaffold is established through dumbbell probe-based RCA (rolling circle amplification), containing repeated CD63 aptamer sections and DNAzyme sections. The original state of the DNAzyme section is locked in a hairpin structure in the detection scaffold. In the presence of sEVs, the CD63 aptamer recognizes and binds with sEVs, leading to the aggregation of sEVs, which can be isolated by low-speed centrifugation and the exposure of the DNAzyme section. After the catalytic fluorescence signal generation from the DNAzyme-based molecular beacon (MB) cleavage, the method exhibited a detection range of 10 2 to 10 6 particles per μL. Considering the high sensitivity and wash-free and easy-to-operate features, the strategy reported herein paves a new avenue for the effective determination of sEVs and other membrane biomolecules in fundamental and applied research.