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

الملخص EN

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.