Dong Ju Son

Inhibitory effect of sesaminol glucosides on lipopolysaccharide-induced NF-κB activation and target gene expression in cultured rat astrocytes

The inflammatory reaction plays an important role in the pathogenesis of the neurodegenerative disorder including Alzheimers disease (AD). Sesame lignan compounds such as sesaminol glucosides (SG) exhibit a range of pharmacological activities including anti-oxidative and anti-inflammatory action. In this study, we tried to elucidate possible effects of SG on lipopolysaccharide (LPS)-induced inflammatory reaction and its underlying mechanism in cultured astrocytes. SG (10-100 microg/ml) inhibited LPS-induced generation of nitric oxide (NO) and reactive oxygen species (ROS), as well as inhibited LPS-induced cytosolic phospholipase A2 (cPLA2), cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) expression dose-dependently. This inhibitory effect of SG on NO and ROS generation was enforced by addition of glutathione (GSH) in culture. In addition, SG prevented LPS-induced DNA binding and transcriptional activity of nuclear factor KappaB (NF)-kappaB. Consistent with the inhibitory effect on NF-kappaB activity, SG inhibits phosphorylation and degradation of inhibitory KappaB (IkappaB), thereby translocation of p50 of NF-kappaB. These data show that SG has an anti-inflammatory effect through inhibition of NF-kappaB, and may be a useful agent for prevention of inflammatory disease like AD.

Inhibitory effect of punicalagin on lipopolysaccharide-induced neuroinflammation, oxidative stress and memory impairment via inhibition of nuclear factor-kappaB.

&NA; Neuroinflammation is significant in the pathogenesis and development of Alzheimers disease (AD). Previously, we showed lipopolysaccharide (LPS)‐induced neuroinflammation caused memory impairment. We investigated the possible preventive effects of punicalagin (PUN), a component of pomegranate, on memory deficiency caused by LPS, along with the fundamental mechanisms. LPS‐treated cultured astrocytes and microglial BV‐2 cells were investigated for anti‐neuroinflammatory effects of PUN. PUN (1.5 mg/kg) ameliorates LPS (250 &mgr;g/kg daily 7 times)‐induced memory impairment as well as prevents the LPS‐induced expression of inflammatory proteins. In in vitro study, we also found that PUN (1 &mgr;g/ml) inhibited the LPS‐(10, 20 and 50 &mgr;M) induced expression of iNOS and Cox‐2 as well as the production of ROS, NO, TNF‐&agr; and IL‐1&bgr;. PUN also suppress activation of NF‐&kgr;B via inhibition of I&kgr;B degradation as well as p50 and p65 translocation into the nucleus in LPS treated mouse brain and cultured astrocytes and microglial BV‐2 cells. Consistent with the inhibitory effect on neuro inflammation, PUN inhibited LPS‐induced A&bgr;1‐42 generation through down‐regulation of APP and BACE1 expression in in vivo and in vitro study. Moreover, PUN directly binds to NF‐&kgr;B subunit p50 evidenced by a docking model and pull down assay. These results suggest that PUN inhibits LPS‐induced memory impairment via anti‐inflammatory and anti‐amylogenic mechanisms through inhibition of NF‐&kgr;B activation. HighlightsNeuroinflammation and amyloidogenesis are main symptoms of Alzheimers disease.NF‐&kgr;B activation can induce the inflammation and amyloidogenesis pathways.Punicalagin inhibits NF‐&kgr;B activation through direct binding to its subunit P50.Punicalagin reduces LPS‐induced neuroinflammation and amyloidogenesis.Punicalagin is a possible candidate for treating Alzheimers disease.

Mutant presenilin 2 causes abnormality in the brain lipid profile in the development of Alzheimer's disease.

Mutation in the presenilin 2 (PS2mt) is known to be one of factors involved in the development of Alzheimer’s disease (AD). It was recently revealed that an abnormality of lipid metabolism is a phenomenon occurring in AD. Therefore, the aim of this study was to investigate the potential relationship between the mutation of PS2 and alterations of the lipid profile within the brain. The results showed there increases in the levels of cholesterol, low density lipoprotein and triglyceride, but a decrease in the level of high density lipoprotein in brain tissues expressing mutant PS2. These findings indicated that PS2mt is involved in the abnormalities of the lipid profile, which could cause or result in the development of AD.

Parkin deficiency exacerbate ethanol-induced dopaminergic neurodegeneration by P38 pathway dependent inhibition of autophagy and mitochondrial function

Parkinsons disease (PD) is a neurodegenerative disease characterized by selective degeneration of dopaminergic neurons in the substantia nigra. Parkin (which encoded by Park2), an E3 ubiquitin ligase, is the most frequently mutated gene that has casually been linked to autosomal recessive early onset familial PD. We tested the effect of Park2 on ethanol-induced dopaminergic neurodegeneration in Park2 knockout (KO) transgenic mice after chronic ethanol feeding. Male Park2 wild type (WT) and KO mice (8 weeks old) were fed on a Lieber-DeCarli diet containing 6.6% ethanol for 2 weeks, and compared their responses. We found that knockout of Park2 exacerbates ethanol-induced behavioral impairment as well as dopamine depletion. In the mechanism study, we found that knockout of Park2 increased reactive oxygen species (ROS) production, mitophagy formation, mitochondrial dysfunction, and expression of pro-apoptotic proteins, but decreased expression of pro-autophagic proteins. Knockout of Park2 also increased ethanol-induced activation of p38 mitogen-activated protein kinase. In addition, ROS production, mitophagy formation, mitochondrial dysfunction, and expression of pro-apoptotic proteins were increased, but expression of pro-autophagic proteins were decreased by a treatment of ethanol (100 μM) in Park2 siRNA-transfacted PC12 cells (5 μM). Moreover, the exacerbating effects of Park2 deletion on ethanol-induced ROS generation, mitophagy, mitochondrial dysfunction as well as cell death were reduced by p38 specific inhibitor (SB203580) in in vitro (10 μM) and in vivo 10 mg/kg). Park2 deficiency exacerbates ethanol-induced dopaminergic neuron damage through p38 kinase dependent inhibition of autophagy and mitochondrial function.

Stimulation of Cell Growth by Erythropoietin in RAW264.7 Cells: Association with AP-1 Activation

Erythropoietin (EPO), a hematopoietic factor, is required for normal erythrocyte developments, but it has been demonstrated to have many other functions, and its receptor is localized in other tissues. In the present study, we investigated whether EPO can promote other cell proliferation and possible molecular mechanisms. EPO restored the inhibition of the RAW264.7 and PC12 cell growth by fetal bovine serum (FBS) withdrawal in a dose dependent manner but not that of other cell types tested. The restoring effect of EPO was completed when the RAW264.7 cells were cultured in the medium containing as low as 3% of FBS, and 10 U/mL EPO could replace FBS. The restoring effect of EPO in the RAW264.7 cells was associated with the increased of c-Fos and c-Jun expression as well as AP-1 activation. These data demonstrate that EPO can stimulate RAW264.7 cell as well as PC12 cell growth even when the cells were cultured without FBS or in the presence of small amounts of FBS in the medium, and this stimulating effect is associated with the activation of AP-1 transcription factor.

Determination of a Ginseng Saponin Metabolite, IH901, in Rat Plasma by Liquid Chromatography‐Tandem Mass Spectrometry

Abstract We developed a liquid chromatography‐tandem mass spectrometric (LC‐MS/MS) method for the determination of a ginseng saponin metabolite, IH901 or compound K (20‐O‐β‐D‐glucopyranosyl‐20(S)‐protopanaxadiol) in rat plasma. The method involves protein precipitation by acetonitrile and HPLC separation of the sample extracts on a reversed‐phase column (X‐terra™ RP18) with isocratic elution of 20 mM ammonium acetate and acetonitrile (30:70, v/v), at a flow rate of 0.2 mL/min. The MS analysis was performed by electrospray positive ionization mass spectrometry using multiple reaction‐monitoring mode. The mass transitions of IH901 and prednisolone (internal standard) were m/z 640→425 and 361→343, respectively. The standard curves for IH901 were linear over the concentration range of 2.0–500 ng/mL. The lower limit of quantification was 2 ng/mL and the limited of detection was 1 ng/mL for IH901. The coefficient of variation of intra‐ and inter‐day assays at five quality control levels ranged from 2.0 to 13.9% and the accuracy varied between 93.2 and 110.5%. This method was used to determine IH901 in plasma samples after the oral administration of a single 30 mg/kg dose on SD rats.