microRNA-21 abrogates palmitate-induced cardiomyocyte apoptosis through caspase-3/NF-kB signal pathways

Abstract

Objective:The aim of the study was to investigate the role of microRNA-21 (miR-21) in cardiomyocyte apoptosis and to determine a possible mechanism.Methods:H9c2 embryonic rat heart-derived cells were used in the study. Cell viability was determined using the 3-(4.5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, and flow cytometry was used to evaluate cell apoptosis. Reverse transcription-polymerase chain reaction and western blot assays were used to detect mRNA and protein expression of the apoptosis-related proteins and miR-21. ELISA was used to detect reactive oxygen species (ROS).Results:Palmitate exposure greatly reduced miR-21 expression in cardiomyocytes. Apoptosis increased when miR-21 was inhibited with or without palmitate exposure. Consistently, reduced apoptosis was observed when miR-21 was overexpressed in cardiomyocytes. Caspase-3 activity was reduced after palmitate exposure. Bcl-2 protein expression was increased in H9c2 cells when transfected with the miR-21 mimic. MiR-21 overexpression alone did not induce ROS or DNA fragmentation; however, in conjunction with palmitate exposure, miR-21 mimic reduced ROS and DNA fragmentation. Moreover, palmitate administration overcame the antioxidant effect of 3 mM N-acetylcysteine to significantly inhibit apoptosis, DNA fragmentation, and caspase-3 activity. The exposure to palmitate greatly reduced p65 and p-p38 expression in the nucleus. A p38 inhibitor had no effect on the expression of Bcl-2 and cleaved caspase-3 in H9c2 cells alone; however, when combined with exposure to palmitate the p38 inhibitor induced Bcl-2 expression and inhibited caspase-3 activity. The p38 inhibitor by itself did not induce apoptosis, ROS production, or DNA fragmentation in H9c2 cells, but when palmitate was included with the p38 inhibitor, apoptosis, ROS production, and DNA fragmentation were reduced.Conclusion:miR-21 protects cardiomyocytes from apoptosis that is induced by palmitate through the caspase-3/NF-κB signal pathways.

The Cell Type–Specific Functions of miR-21 in Cardiovascular Diseases

“…As highlighted above, miR-21 participates in infarction injuries, cardiac remodeling, atherosclerosis, arrhythmias, and cardiomyopathy, which are caused by infection or metabolic disorders (Thum et al, 2008;Thum, 2012Thum, , 2014van Rooij and Olson, 2012;Fiedler and Thum, 2013;Li et al, 2016;Dai et al, 2018;Zhou et al, 2018). This indicates its potential as a clinical therapeutic target.…”

“…The miR-21 expression is particularly elevated in highglucose-cultured CFs, which results in increased collagen crosslink and cardiac fibrosis via Jun amino-terminal kinases/stressactivated protein kinases (JNK/SAPK) and p38 by regulating dual specific phosphatase 8 (DUSP8) (Liu et al, 2014). On the contrary, Zhou et al (2018) reported that miR-21 was downregulated in palmitate-treated CMs. miR-21 protected CMs from apoptosis through inhibiting p65 and p-p38 expression.…”

“…The reason for the varied observations might be attributed to the fact that, although high glucose and high fat contribute to the etiology of diabetic cardiomyopathy, different sources have varied effects on miR-21 expression, which could exert diverse functions in multiple cell types. Liu et al (2014) observed that high glucose increased the levels of miR-21, whereas Dai et al (2018) and Zhou et al (2018) observed that miR-21 expression decreased in response to palmitate. In addition, Liu et al (2014) observed that miR-21 increased collagen cross-link in CFs and cardiac fibrosis, whereas Dai et al (2018) and Zhou et al (2018) found that miR-21 exerted a protective effect in CMs.…”

miR-21 in Human Cardiomyopathies

“…In most cases, miR-21 expression levels were elevated in stress conditions such as oxidative stress, high glucose, and hypoxia (59)(60)(61)(62). However, oxygen-glucose deprivation (OGD) and palmitate exposure can considerably decrease miR-21 expression levels in cardiomyocytes (63,64).…”

lncRNA NONHSAT069381 and NONHSAT140844 Increase in Aging Human Blood, Regulating Cardiomyocyte Apoptosis

“…Sequential activation of caspases plays a central role in the execution phase of cell apoptosis [15]. Previous studies have shown that proapoptotic members of caspase-8 were regarded as the initiators of apoptosis and caspase-3 was the executor and terminator of multiple apoptotic pathways [16][17][18][19]. Among the human inhibitors of apoptosis proteins (IAPs), X-chromosome-linked IAP (XIAP) is the most studied [20].…”