MiR-181c-5p Promotes Inflammatory Response during Hypoxia/Reoxygenation Injury by Downregulating Protein Tyrosine Phosphatase Nonreceptor Type 4 in H9C2 Cardiomyocytes

Abstract

Background. Constitutive nuclear factor kappa B (NFκB) activation has been shown to exacerbate during myocardial ischemia/reperfusion (I/R) injury. We recently showed that miR-181c-5p exacerbated cardiomyocytes injury and apoptosis by directly targeting the 3′-untranslated region of protein tyrosine phosphatase nonreceptor type 4 (PTPN4). However, whether miR-181c-5p mediates cardiac I/R injury through NFκB-mediated inflammation is unknown. Thus, the present study aimed to investigate the role of miR-181c-5p during myocardial I/R injury and explore its mechanism in relation to inflammation in H9C2 cardiomyocytes. Methods and Results. In hypoxia/reoxygenation (H/R, 6 h hypoxia followed by 6 h reoxygenation)-stimulated H9C2 cardiomyocytes or postischemic myocardium of rat, the expression of miR-181c-5p was significantly upregulated, which was concomitant increased NFκB activity when compared to the nonhypoxic or nonischemic control groups. This is indicative that miR-181c-5p may be involved in NFκB-mediated inflammation during myocardial I/R injury. To investigate the potential role of miR-181c-5p in H/R-induced cell inflammation and injury, H9C2 cardiomyocytes were transfected with the miR-181c-5p agomir. Overexpression of miR-181c-5p significantly aggravated H/R-induced cell injury (increased lactate dehydrogenase (LDH) level) and exacerbated NFκB-mediated inflammation (greater phosphorylation and degradation of IκBα, phosphorylation of p65, and increased levels of proinflammatory cytokines tumor necrosis factor α (TNFα), interleukin (IL)-6, and IL-1β). In contrast, inhibition of miR-181c-5p by its antagomir transfection in vitro had the opposite effect. Furthermore, overexpression of miR-181c-5p significantly enhanced lipopolysaccharide-induced NFκB signalling. Additionally, knockdown of PTPN4, the direct target of miR-181c-5p, significantly aggravated H/R-induced phosphorylation and degradation of IκBα, phosphorylation of p65, and the levels of proinflammatory cytokines. PTPN4 knockdown also cancelled miR-181c-5p antagomir mediated anti-inflammatory effects in H9C2 cardiomyocytes during H/R injury. Conclusions. It is concluded that miR-181c-5p may exacerbate myocardial I/R injury and NFκB-mediated inflammation via PTPN4, and that targeting miR-181c-5p/PTPN4/NFκB signalling may represent a novel strategy to combat myocardial I/R injury.

miR-181c-5p mediates apoptosis of vascular endothelial cells induced by hyperoxemia via ceRNA crosstalk

“…Many studies have shown that miR-181c-5p has multiple functions, such as regulating cell apoptosis, inflammation, immunity, and mitochondrial function. MiR-181c-5p could down-regulate PTPN4 to promote the inflammatory response during ischemia/reperfusion injury, and also could regulates ischemia/reperfusion injury-induced neuronal cell death by targeting c-Fos 42 , 43 . Nevertheless, miR-181c-5p remains poorly studied in vascular endothelial cells.…”

Differential Expression of microRNAs Correlates With the Severity of Experimental Autoimmune Cystitis

“…Further, we also observed an increase in miR-181 in the UB and ILNs of IC mice compared to the control. MiR-181 plays a pro-inflammatory role in hypoxia/reoxygenation injury through non-receptor tyrosine phosphatase 4 (PTPN4) heart cells (32). MiR-181 also regulates T cell-based immune responses via its crucial role in the activation of CD4 + T cells (33).…”

MicroRNA-503 Exacerbates Myocardial Ischemia/Reperfusion Injury via Inhibiting PI3K/Akt- and STAT3-Dependent Prosurvival Signaling Pathways

“…The cytoplasmic enzyme lactate dehydrogenase (LDH) is released into the cell culture medium from the damaged cells. LDH activity was determined in cell culture supernatant with the use of Cytotoxicity Detection Kit (Roche, Mannheim, Germany) according to the manufacturer's instructions as described [ 34 ]. The absorbance was measured at wavelength of 492 nm with reference wavelength 620 nm.…”