Luteolin protects PC12 cells from rotenone-induced apoptosis

The 4-hydroxy-flavonoid compound luteolin is a phytoestrogen with antioxidant, anti-inflammatory, and anti-tumor properties. The present study analyzed the protective effects of luteolin against rotenone-induced PC12 cell apoptosis in a model of Parkinson＇s disease （PD）. Rotenone （1.6 μmol/L） was utilized to establish the In vitro PD model, resulting in low cell viability and an apoptotic rate of 36.1%. Luteolin （100 μmol/L） pretreatment significantly ameliorated rotenone-induced damage, improved cell morphology and viability, decreased comet tail length, reduced the rate of apoptosis （11.8%）, and down-regulated cleaved caspase-3 expression. Results demonstrate that luteolin protects PC12 cells against rotenone-induced apoptosis by decreasing cleaved caspase-3 expression.

Oligomeric proanthocyanidin protects retinal ganglion cells against oxidative stress-induced apoptosis

The death of retinal ganglion cells is a hallmark of many optic neurodegenerative diseases such as glaucoma and retinopathy. Oxidative stress is one of the major reasons to cause the cell death. Oligomeric proanthocyanidin has many health beneficial effects including antioxidative and neuro- protective actions. Here we tested whether oligomeric proanthocyanidin may protect retinal gan- glion cells against oxidative stress induced-apoptosis in vitro. Retinal ganglion cells were treated with hydrogen peroxide with or without oligomeric proanthocyanidin. 3-（4,5-Dimethylthiazol-2-yl）- 2,5-diphenyltetrazolium bromide （MTT） assay showed that treating retinal ganglion cell line RGC-5 cells with 20 pmol/L oligomeric proanthocyanidin significantly decreased the hydrogen peroxide （H202） induced death. Results of flow cytometry and Hoechst staining demonstrated that the death of RGC-5 cells was mainly caused by cell apoptosis. We further found that expression of pro-apoptotic Bax and caspase-3 were significantly decreased while anti-apoptotic Bcl-2 was greatly increased in H202 damaged RGC-5 cells with oligomeric proanthocyanidin by western blot assay. Furthermore, in retinal explant culture, the number of surviving retinal ganglion cells in H202-damaged retinal ganglion cells with oligomeric proanthocyanidin was significantly increased. Our studies thus demonstrate that oligomeric proanthocyanidin can protect oxidative stress-injured retinal ganglion cells by inhibiting apoptotic process.

Functional characterization of the NF-kB binding site in the human NOD2 promoter

Nucleotide-binding and oligomerization domain 2(NOD2),a member of the NOD protein family,plays an important role in innate immunity.In response to pathogen attack,NOD2 stimulates cytokine and defensin production by activating nuclear factor(NF)-kB,a key transcription factor responsible for mediating downstream reactions.However,the mechanism linking NOD2 regulation and NF-kB activation is poorly understood.Using bioinformatics,we found a completely preserved canonical NF-kB binding site in the NOD2 core promoter(216 to 225 bp)in both humans and chimpanzees.The functional role of this NF-kB binding site was investigated using the enhanced green fluorescent protein(EGFP)reporter system,site-directed mutagenesis,the NF-kB activation inhibitor(JSH-23)and the chromatin immunoprecipitation(ChIP)assay.The results show that the NF-kB binding site is critical for regulation of the NOD2 gene.Either deletion of the NF-kB binding elements within the NOD2 promoter or treatment with an NF-kB activation inhibitor could lead to a significant loss of NOD2 promoter activity as detected by reporter gene assay.The canonical NF-kB binding site was bound by NF-kB as determined by the ChIP method.Based on these results,we suggest a positive feedback regulation between NF-kB and NOD2,which may represent an efficient mechanism in response to pathogen invasion.