Abstract
MiR-499a-5p was significantly downregulated in degenerative tissues and correlated with apoptosis. Nonetheless, the biological function of miR-499a-5p in acute ischemic stroke has been still unclear. In this study, we found that the plasma levels of miR-499a-5p were significantly downregulated in 64 ischemic stroke patients and negatively correlated with the National Institutes of Health Stroke Scale score. Then, we constructed cerebral ischemia/reperfusion (I/R) injury in rats after middle cerebral artery occlusion and subsequent reperfusion and oxygen-glucose deprivation and reoxygenation (OGD/R)-treated SH-SY5Y cell model. Transfection with miR-499a-5p mimic was accomplished by intracerebroventricular injection in the in vivo I/R injury model. We further found that miR-499a-5p overexpression decreased infarct volumes and cell apoptosis in the in vivo I/R stroke model using TTC and TUNEL staining. PDCD4 was a direct target of miR-499a-5p by luciferase report assay and Western blotting. Knockdown of PDCD4 reduced the infarct damage and cortical neuron apoptosis caused by I/R injury. MiR-499a-5p exerted neuroprotective roles mainly through inhibiting PDCD4-mediated apoptosis by CCK-8 assay, LDH release assay, and flow cytometry analysis. These findings suggest that miR-499a-5p might represent a novel target that regulates brain injury by inhibiting PDCD4-mediating apoptosis.
Highlights
Ischemic stroke is identified as a type of cerebrovascular disease accounting for nearly 90% of stroke cases with lower life quality of victims and huger public health burden (Benjamin et al 2018; LuengoFernandez et al 2013)
RT-qPCR analysis first demonstrated that the expression of miR-499a-5p was significantly decreased in the I/R group compared with sham group, but notably increased after intracerebroventricular injection of miR-499a-5p mimic in I/R group (Figure 2A)
Western blot analysis showed that the protein levels of MRPS35, ARGLU1, PFN2 and HNRNPC were downregulated in different degrees after miR-499a-5p mimic transfection compared with siNC transfection in oxygen-glucose deprivation and reoxygenation (OGD/R) cell model (Figure 1S-B). we focused on programmed cell death 4 (PDCD4), closely associated with the occurrence of apoptosis, has been involved in several miRNAs-meditated I/R injury (Cheng et al 2009; Zheng et al 2020), which was selected as a potential target of miR-499a-5p
Summary
Ischemic stroke is identified as a type of cerebrovascular disease accounting for nearly 90% of stroke cases with lower life quality of victims and huger public health burden (Benjamin et al 2018; LuengoFernandez et al 2013). Sudden insufficient blood flow to an area of the brain is the main characteristics of ischemic stroke, which could cause neuronal cell apoptosis, necrosis and other metabolism-related disorders (Tobin et al 2014). Despite the advances in rapid restoration of the blood supply for ischemic stroke, blood flow reperfusion, a process termed cerebral ischemia/reperfusion (I/R) injury seriously limits its development (Chomova and Zitnanova 2016). MicroRNAs (miRNAs/miRs), small endogenous noncoding RNA molecules (18–25 nts) regulate a various of biological processes, including cell proliferation, apoptosis and neuroinflammation primarily through the interaction with mRNAs via binding their 3′-untranslated region (3′-UTR) regions (Bartel 2004; Qian Zhang 2017; Zhong et al 2019). MiR-132 could attenuate cerebral injury by protecting blood-brain barrier disruption in ischemia stroke (Zuo et al 2019). It's worth noting that Kang et al (Liu et al 2019)
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