Circular RNA-circPan3 attenuates cardiac hypertrophy via miR-320-3p/HSP20 axis

BACKGROUND

Circular RNAs are enriched in cardiac tissue and play important roles in the pathogenesis of heart diseases. In this study, we aimed to investigate the regulatory mechanism of a conserved heart-enriched circRNA, circPan3, in cardiac hypertrophy.

METHODS

Cardiac hypertrophy was induced by isoproterenol. The progression of cardiomyocyte hypertrophy was assessed by sarcomere organization staining, cell surface area measurement, and expression levels of cardiac hypertrophy markers. RNA interactions were detected by RNA pull-down assays, and methylated RNA immunoprecipitation was used to detect m6A level.

RESULTS

The expression of circPan3 was downregulated in an isoproterenol-induced cardiac hypertrophy model. Forced expression of circPan3 attenuated cardiomyocyte hypertrophy, while inhibition of circPan3 aggravated cardiomyocyte hypertrophy. Mechanistically, circPan3 was an endogenous sponge of miR-320-3p without affecting miR-320-3p levels. It elevated the expression of HSP20 by endogenously interacting with miR-320-3p. In addition, circPan3 was N6-methylated. Stimulation by isoproterenol downregulated the m6A eraser ALKBH5, resulting in N6-methylation and destabilization of circPan3.

CONCLUSIONS

Our research is the first to report that circPan3 has an antihypertrophic effect in cardiomyocytes and revealed a novel circPan3-modulated signalling pathway involved in cardiac hypertrophy. CircPan3 inhibits cardiac hypertrophy by targeting the miR-320-3p/HSP20 axis and is regulated by ALKBH5-mediated N6-methylation. This pathway could provide potential therapeutic targets for cardiac hypertrophy.

Clinical value of serum miR-320-3p expression in predicting the prognosis of sepsis-induced acute kidney injury

BACKGROUND

For investigating the expression of miR-320-3p in children with sepsis-induced acute kidney injury (AKI) and its prognostic value.

METHODS

A total of 142 patients were grouped into a survival group (n = 95) and death group (n = 47), which was based on their 28-day survival. Serum degrees of miR-320-3p, neutrophil gelatinase-associated lipid carrier protein (NGAL) and kidney injury molecule-1 (KIM-1) were detected. The Acute Physiology and Chronic Health scoring system Ⅱ (APACHE Ⅱ) marks were recorded. Target gene forecast and functional enrichment discussion of miR-320-3p were performed, and a protein-protein interaction (PPI) network diagram was plotted by applying bioinformatics methods. Multivariate logistic regression, ROC curve and Pearson correlation analysis were applied.

RESULTS

The death group showed greatly higher serum levels of miR-320-3p, KIM-1 and APACHE Ⅱ scores than the survival group (p < 0.01). Multivariate logistic regression analysis showed that levels of miR-320-3p, NGAL, KIM-1 and APACHE Ⅱ scores were independent risk elements for death in sepsis children with AKI (p < 0.01). According to ROC curve analysis, the region under the curve (0.963, 95% CI: 0.908-0.996) of miR-320-3p, NGAL, KIM-1 levels and APACHE Ⅱ scores combined to forecast the death of kids suffering from sepsis and AKI were the biggest. According to correlation analysis, the expression degree of serum miR-320-3p in the death group was positively correlated with NGAL, KIM-1 and APACHE Ⅱ scores (all p < 0.01).

CONCLUSIONS

The expression level of serum miR-320-3p in children with sepsis-induced AKI was significantly increased, and the combination of NGAL, KIM-1 and APACHE Ⅱ scores has good value for prognosis prediction in children.

MiR-320-3p Regulates the Proliferation and Differentiation of Myogenic Progenitor Cells by Modulating Actin Remodeling

Skeletal myogenesis is essential for the maintenance of muscle quality and quantity, and impaired myogenesis is intimately associated with muscle wasting diseases. Although microRNA (miRNA) plays a crucial role in myogenesis and relates to muscle wasting in obesity, the molecular targets and roles of miRNAs modulated by saturated fatty acids (SFA) are largely unknown. In the present study, we investigated the role of miR-320-3p on the differentiation of myogenic progenitor cells. Palmitic acid (PA), the most abundant dietary SFA, suppressed myogenic factors expression and impaired differentiation in C2C12 myoblasts, and these effects were accompanied by CFL2 downregulation and miR-320-3p upregulation. In particular, miR-320-3p appeared to target CFL2 mRNA directly and suppress the expression of CFL2, an essential factor for filamentous actin (F-actin) depolymerization. Transfection of myoblasts with miR-320-3p mimic increased F-actin formation and nuclear translocation of Yes-associated protein 1 (YAP1), a key component of mechanotransduction. Furthermore, miR-320-3p mimic increased myoblast proliferation and markedly impeded the expression of MyoD and MyoG, consequently inhibiting myoblast differentiation. In conclusion, our current study highlights the role of miR-320-3p on CFL2 expression, YAP1 activation, and myoblast differentiation and suggests that PA-inducible miR-320-3p is a significant mediator of muscle wasting in obesity.

Circ_UTRN ameliorates caerulein-induced acute pancreatitis in vitro via reducing inflammation and promoting apoptosis through miR-320-3p/PTK2 axis

OBJECTIVES

Circular RNAs (circRNAs) have been demonstrated to play important roles in acute pancreatitis (AP). Herein, this study aimed to investigate the role and mechanism of circRNAs utrophin (circ_UTRN) in AP.

METHODS

In vitro cultured rat pancreatic acinar cell line AR42J was exposed to caerulein (10 nmol/L) to mimic an AP cell model. The levels of circ_UTRN and microRNA (miR)-320-3p and protein tyrosine kinase 2 (PTK2) were examined using quantitative real-time polymerase chain reaction and Western blot assays. Cell apoptosis was analysed by flow cytometry and Western blot assays. ELISA was employed to detect the levels of tumour necrosis factor-α (TNF-α), IL-1β and IL-6. The binding interaction between miR-320-3p and circ_UTRN or PTK2 was verified using dual-luciferase reporter assay.

KEY FINDINGS

The expression of circ_UTRN was decreased by caerulein in pancreatic acinar cells, ectopic overexpression of circ_UTRN reduced inflammation and promoted apoptosis in caerulein-mediated pancreatic acinar cells. In a mechanical study, circ_UTRN served as a sponge of miR-320-3p, and miR-320-3p directly targeted PTK2. Rescue assay suggested that the promotion of apoptosis and inhibition of inflammation induced by circ_UTRN re-expression in caerulein-mediated pancreatic acinar cells were partially abolished by miR-320-3p overexpression or PTK2 knockdown. Besides that, miR-320-3p inhibition impaired caerulein-induced cell apoptosis arrest and inflammation via targeting PTK2.

CONCLUSIONS

Up-regulation of circ_UTRN in pancreatic acinar cells attenuates caerulein-evoked cell apoptosis arrest and inflammation enhancement via miR-320-3p/PTK2, suggesting that circ_UTRN/miR-320-3p/PTK2 axis might be engaged in caerulein-induced AP.

Tcf3-activated lncRNA Gas5 regulates newborn mouse cardiomyocyte apoptosis in diabetic cardiomyopathy

Diabetic cardiomyopathy can cause cardiac dysfunction and eventually lead to heart failure and sudden death. Long noncoding RNA (lncRNA) Gas5 has been reported to play a function in cardiomyocyte. Here we studied the function of Gas5 on newborn mouse cardiomyocyte (NMC) apoptosis to detect its molecular mechanism. High-glucose treatment was implemented to induce the apoptosis of NMC in this study. And terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, JC-1 assay, and flow cytometry analysis were conducted to know about the apoptosis of NMC when Gas5 and Tcf3 were silenced. Meanwhile, RNA pull-down assay and luciferase reporter assay were conducted to verify the binding of RNAs. Finally, rescue assay was implemented to evaluate the influence on apoptosis situation affected by competing endogenous RNA pathways. Tcf3 was found to bind to the Gas5 promoter to activate the expression of Gas5. Meanwhile, Gas5 and Tcf3 were both found to promote the apoptosis of NMC. Also, mmu-miR-320-3p could bind to Gas5 and Tcf3. Moreover, the Gas5/miR-320-3p/Tcf3 pathway was found to modulate the apoptosis of NMC. In conclusion, Tcf3-activated lncRNA Gas5 regulates NMC apoptosis in diabetic cardiomyopathy.