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The aim of the present study was to observe the dynamic changes of the growth arrest and DNA damage-inducible 153 (GADD153) gene and caspase-12 in the brain tissue of rats with cerebral ischemia-reperfusion injury (CIRI) and the impact of curcumin pretreatment. A total of 60 rats were randomly divided into the normal group (N), the sham operation group (S), the dimethyl sulfoxide control group (D) and the curcumin treatment group (C). For group D and C, 12 (T1), 24 (T2) and 72 h (T3) of reperfusion were performed after 2 h ischemia. The expression levels of GADD153 and caspase-12 in the brain tissue were detected and compared among the groups by immunohistochemistry, immunofluorescence double staining and western blotting. The expression levels of GADD153 and caspase-12 were increased at T1compared with groups N and S, and the expression of caspase-12 peaked at T2 in group D, while GADD153 was increased until T3 in group D. Compared with group D, the expression levels of GADD153 and caspase-12 in group C at T2 and T3 were significantly decreased (P<0.05). Endoplasmic reticulum stress is involved in the pathological process of CIRI. Curcumin may decrease the expression levels of the above two factors, thus exhibiting protective effects against CIRI in rats.

RNAi (RNA interference) is an important defense response against virus infection in plants. The core machinery of the RNAi pathway in plants include DCL (Dicer Like), AGO (Argonaute) and RdRp (RNA dependent RNA polymerase). Although involvement of these RNAi components in virus infection responses was demonstrated in Arabidopsis thaliana, their contribution to antiviral immunity in Nicotiana benthamiana, a model plant for plant-pathogen interaction studies, is not well understood. In this study, we investigated the role of N. benthamiana NbAGO2 gene against TMV (Tomato mosaic virus) infection. Silencing of NbAGO2 by transient expression of an hpRNA construct recovered GFP (Green fluorescent protein) expression in GFP-silenced plant, demonstrating that NbAGO2 participated in RNAi process in N. benthamiana. Expression of NbAGO2 was transcriptionally induced by both MeSA (Methylsalicylate acid) treatment and TMV infection. Down-regulation of NbAGO2 gene by amiR-NbAGO2 transient expression compromised plant resistance against TMV infection. Inhibition of endogenous miR403a, a predicted regulatory microRNA of NbAGO2, reduced TMV infection. Our study provides evidence for the antiviral role of NbAGO2 against a Tobamovirus family virus TMV in N. benthamiana, and SA (Salicylic acid) mediates this by induction of NbAGO2 expression upon TMV infection. Our data also highlighted that miR403a was involved in TMV defense by regulation of target NbAGO2 gene in N. Benthamiana.

Excessive K(+) efflux promotes central neuronal apoptosis; however, the type of potassium channel that mediates K(+) efflux in response to different apoptosis-inducing stimuli is still unknown. It is hypothesized that the activation of large-conductance Ca(2+)-activated K(+) channels (BKCa) mediates hypoxia/reoxygenation (H/R)- and ischemia/reperfusion (I/R)-induced neuronal apoptosis. Rat hippocampal neuronal cultures underwent apoptosis after reoxygenation, as assessed by morphologic observation, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and caspase-3 activation. Single-channel recordings revealed upregulation of BKCa channel activity 6 h after reoxygenation, which might be caused by elevated cytosolic Ca(2+). The K(+) ionophore valinomycin and the BKCa channel opener NS1619 induced neuronal apoptosis. Transfection of the BKCa channel α subunit into Chinese hamster ovary (CHO-K1) cells, which do not express endogenous K(+) channels, or into neurons will induce cell apoptosis, indicating that the opening of the BKCa channel serves as a pivotal event in mediating cell apoptosis. The specific BKCa channel blockers charybdotoxin and iberiotoxin and the nonselective K(+) channel blocker tetraethylammonium at concentrations more specific to the BKCa channel were neuroprotective. The A-type potassium channel blocker 4-aminopyridine and apamin, a small-conductance Ca(2+)-activated K(+) channel blocker, were not protective. This result suggests the involvement of the BKCa channel in H/R-induced apoptosis. Similarly, specific BKCa channel blockers also showed neuroprotection in neurons subjected to oxygen-glucose deprivation/reoxygenation or animals subjected to forebrain ischemia-reperfusion. These results demonstrate that the over-activity of BKCa channels mediates hippocampal neuronal damage induced by H/R in vitro and I/R in vivo.

This study aimed to identify potential miRNAs highly associated with the response to brain ischemic stroke. The miRNAs microarray expression profiles data were downloaded from Gene Expression Omnibus database under accession number GSE51586, including three ischemia and three ipsilateral normal samples from mouse brain tissues. Limma package was used to identify differentially expressed miRNAs between ischemia and ipsilateral normal samples. The common target genes of miRNA predicted from TargetScan, PicTar, miRanda and DIANA-microT databases were used as the candidate subset in which functional modules were identified by performing gene ontology enrichment analysis using ClusterProfile. Finally, the miRNA functional synergistic network was constructed by assembling all miRNA synergistic pairs. Fifty-one differentially expressed miRNAs were identified between ischemia and ipsilateral normal samples, including 32 up- and 19 down-regulated miRNAs. Among them, 24 miRNAs can commonly regulate at least one target gene and thus were used to construct a network, which included 274 pairs of co-regulating miRNAs. Further, 242 pairs of miRNAs interaction involving 23 miRNAs were shown to be synergetic in function. Sixteen miRNAs forming 20 miRNAs interaction pairs participated in inflammatory response, such as mir-185 and mir-674-3p. The 16 miRNAs related to inflammatory response during ischemic stroke may provide underlying targets for prevention and treatment of stroke.

Nitric oxide (NO) and p38 have been shown to be involved in the ischemia/hypoxia-induced neuronal injury. In this study, we examined the activation patterns of mitogen-activated protein kinases and explored the relationship between NO and p38 in a model of hippocampal neuronal death induced by hypoxia/reoxygenation (H/R). p38 activity increased robustly during hypoxia and after reoxygenation, while the increase of c-Jun amino-terminal kinase and extracellular signal-related kinase activities showed mild tendency. Inhibition of p38 with SB203580 or SB202190 rescued neuronal death, whereas inhibition of extracellular signal-related kinases with PD98059 or c-Jun amino-terminal kinases with SP600125 offered no protection. p38 inhibitors also reduced neuronal death induced by the NO donor S-nitrosoglutathione. L-NAME, a nonspecific NO synthase inhibitor, blocked the p38 activation and rescued H/R-induced neuronal death. These results suggest that NO is an upstream signal of p38 that mediates the H/R-induced neuronal death.