Woo Jin Jun

Epigallocatechin-3-gallate, a histone acetyltransferase inhibitor, inhibits EBV-induced B lymphocyte transformation via suppression of RelA acetylation.

Because the p300/CBP-mediated hyperacetylation of RelA (p65) is critical for nuclear factor-kappaB (NF-kappaB) activation, the attenuation of p65 acetylation is a potential molecular target for the prevention of chronic inflammation. During our ongoing screening study to identify natural compounds with histone acetyltransferase inhibitor (HATi) activity, we identified epigallocatechin-3-gallate (EGCG) as a novel HATi with global specificity for the majority of HAT enzymes but with no activity toward epigenetic enzymes including HDAC, SIRT1, and HMTase. At a dose of 100 micromol/L, EGCG abrogates p300-induced p65 acetylation in vitro and in vivo, increases the level of cytosolic IkappaBalpha, and suppresses tumor necrosis factor alpha (TNFalpha)-induced NF-kappaB activation. We also showed that EGCG prevents TNFalpha-induced p65 translocation to the nucleus, confirming that hyperacetylation is critical for NF-kappaB translocation as well as activity. Furthermore, EGCG treatment inhibited the acetylation of p65 and the expression of NF-kappaB target genes in response to diverse stimuli. Finally, EGCG reduced the binding of p300 to the promoter region of interleukin-6 gene with an increased recruitment of HDAC3, which highlights the importance of the balance between HATs and histone deacetylases in the NF-kappaB-mediated inflammatory signaling pathway. Importantly, EGCG at 50 micromol/L dose completely blocks EBV infection-induced cytokine expression and subsequently the EBV-induced B lymphocyte transformation. These results show the crucial role of acetylation in the development of inflammatory-related diseases.

Gallic Acid Suppresses Lipopolysaccharide-Induced Nuclear Factor-κB Signaling by Preventing RelA Acetylation in A549 Lung Cancer Cells

Although multiple studies have revealed that gallic acid plays an important role in the inhibition of malignant transformation, cancer development, and inflammation, the molecular mechanism of gallic acid in inflammatory diseases is still unclear. In this study, we identified gallic acid from Rosa rugosa as a histone acetyltransferase (HAT) inhibitor with global specificity for the majority of HAT enzymes, but with no activity toward epigenetic enzymes including sirtuin (silent mating type information regulation 2 homologue) 1 (S. cerevisiae), histone deacetylase, and histone methyltransferase. Enzyme kinetic studies indicated that gallic acid uncompetitively inhibits p300/CBP-dependent HAT activities. We found that gallic acid inhibits p300-induced p65 acetylation, both in vitro and in vivo, increases the level of cytosolic IκBα, prevents lipopolysaccharide (LPS)-induced p65 translocation to the nucleus, and suppresses LPS-induced nuclear factor-κB activation in A549 lung cancer cells. We have also shown that gallic acid treatment inhibits the acetylation of p65 and the LPS-induced serum levels of interleukin-6 in vivo. Importantly, gallic acid generally inhibited inflammatory responses caused by other stimuli, including LPS, IFN-γ, and interleukin-1β, and further downregulated the expression of nuclear factor-κB–regulated antiapoptotic genes. These results show the crucial role of acetylation in the development of inflammatory diseases. (Mol Cancer Res 2009;7(12):2011–21)

Antioxidant effects of Origanum majorana L. on superoxide anion radicals

A purified compound with antioxidant properties (28 mg), T3b, was isolated from a methanol extract (10 g) of Origanum majorana L. by sequential procedures, with silica gel column, thin-layer, and LH-20 Sephadex gel column chromatographies. The in vitro scavenging activity of T3b on superoxide anion radical (O2−) was investigated and compared to those of seven commercially available synthetic or natural antioxidants. Of those, the strongest scavenging action was observed in T3b with an IC50 of 1.44 μg/ml. The T3b also exhibited significant inhibitory effects on 12-O-tetradecanolyphorbol-13-acetate (TPA)-induced O2− generation and hydrogen peroxide formation in differentiated HL-60 cells, indicating that the isolated compound is a potent chemopreventer. The purified compound from O. majorana L. was shown to possess both O2− scavenging activity and an inhibitory effect against TPA-induced O2− generation.

Gallic acid, a histone acetyltransferase inhibitor, suppresses β‐amyloid neurotoxicity by inhibiting microglial‐mediated neuroinflammation

SCOPEnWe examined the biological effect of gallic acid (GA) as a nuclear factor (NF)-κB acetyltransferase inhibitor on microglial-mediated β-amyloid neurotoxicity and restorative effects on the Aβ-induced cognitive dysfunction.nnnMETHODS AND RESULTSnThe protective effects of GA on the survival of neuronal cells were assessed with an MTT assay and a co-culture system. For the co-culture experiments, both BV-2 and primary microglia cells were treated with GA prior to Aβ stimulation, and conditioned media were transferred to Neuro-2A cells. The mRNA and protein levels of inflammatory cytokines in both microglia and Neuro-2A cells were assessed with real-time polymerase chain reaction and western blotting. Inhibition of nuclear factor kappa B (NF-κB) acetylation with GA treatment resulted in reduced cytokine production in microglia cells and protection of neuronal cells from Aβ-induced neurotoxicity. Furthermore, we observed a restorative effect of GA on Aβ-induced cognitive dysfunction in mice with Y-maze and passive avoidance tests. Finally, we found that GA treatment efficiently blocked neuronal cell death by downregulating the expression of cytokines and the in vivo levels of NF-κB acetylation.nnnCONCLUSIONnThese results suggest that selective inhibition of NF-κB acetylation by the histone acetyltransferase inhibitor GA is a possible therapeutic approach for alleviating the inflammatory progression of Alzheimer disease.

Ferulic Acid Supplementation Prevents Trimethyltin-Induced Cognitive Deficits in Mice

This study’s objective was to clarify the ameliorative effects ferulic acid (4-hydroxy-3-methoxycinnamic acid) has against cognitive deficits and ChAT activation in trimethyltin (TMT) induced, memory injured mice following a 28-d ferulic acid treatment. After administering TMT for 3 d, each mouse performed Y-maze and passive avoidance tests to check immediate working memory performance and cognitive function. The results showed that ferulic acid administration attenuated TMT-induced memory injury and a decline in ChAT activity in the mice. This suggests that ferulic acid might be useful for preventing cognitive dysfunction as well as for boosting the activation of ChAT in dementia.

Ameliorative effect of 1,2-benzenedicarboxylic acid dinonyl ester against amyloid beta peptide-induced neurotoxicity.

Amyloid beta peptide (Aβ)-induced oxidative stress may be linked to neurodegenerative disease. Ethanol extracts of Rosa laevigata protected PC12 cells from hydrogen peroxide-induced oxidative stress. (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) reduction assays revealed a significant increase in cell viability when oxidatively stressed PC12 cells were treated with R. laevigata extract. The effect of R. laevigata on oxidative stress-induced cell death was further investigated by lactate dehydrogenase release assays and trypan blue exclusion assays. Administration of 1,2-benzenedicarboxylic acid dinonyl ester from R. laevigata extract to mice infused with Aβ significantly reversed learning and memory impairment in behavioural tests. After behavioural testing, the mice were sacrificed and brains were collected for the examination of lipid peroxidation, catalase activity and acetylcholinesterase (AchE) activity. These results suggest that 1,2-benzenedicarboxylic acid dinonyl ester from R. laevigata extract may be able to reduce Aβ-induced neurotoxicity, possibly by reducing oxidative stress. Therefore, R. laevigata extract may be useful for the prevention of oxidative stress-induced neurodegenerative disorders.

Effects of Polysaccharides from Rhizomes of Curcuma zedoaria on Macrophage Functions

The effects of Curcuma zedoaria, which is used as a condiment, in perfumery, and as a medicine, on immune response were investigated by measuring macrophage-stimulating activity in macrophages and RAW 264.7 cells. In this study, CZ-1 and CZ-1-III, the fractions partially purified from C. zedoaria, had a strong, dose-dependent lysosomal enzyme activity. It was suggested that active portions of CZ-1-III were polysaccharides rather than proteins. Phagocytic activity increased as a similar pattern in both the Gram-negative and Gram-positive bacteria, time-dependently. It was demonstrated that CZ-1-III can augment the oxygen burst response but had an even higher activity in vivo than in vitro. Also a significant increase of H2O2, NO, and TNF-α production was observed. However, the production of TNF-α at the concentration of 1,000 μg/ml decreased. These data suggested that C. zedoaria had macrophage-stimulating activity and the possibility of being used as a biological response modifier.

Neuroprotective effects of Eriobotrya japonica against β-amyloid-induced oxidative stress and memory impairment

The generation of oxygen free radicals and oxidative damage is believed to be involved in the pathogenesis of neurodegenerative disorders. Eriobotrya japonica has been used to treat several diseases in East Asia. In this study, we investigated the protective effect of an E. japonica extract against Aβ peptide-induced oxidative stress. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay demonstrated that the E. japonica extract scavenged approximately 40% of DPPH radicals. Also, treatment of the E. japonica extract inhibited Aβ(1-42)-mediated neuronal cell death. Furthermore, treatment of E. japonica extract efficiently suppressed the increase in intracellular ROS triggered by the Aβ(1-42) peptide. Importantly, mice pre-treated with the E. japonica extract showed restoration of alternation behavior and reversal of Aβ(1-42)-induced memory impairment. Consequently, the E. japonica extract substantially inhibited the increase in lipid peroxidation and restored superoxide dismutase activity. These results suggest that E. japonica protects from oxidative stress and cognitive deficits induced by the Aβ peptide.

DNAJB1 destabilizes PDCD5 to suppress p53-mediated apoptosis.

Although PDCD5 promotes p53-mediated apoptosis in various cancers, little is known about PDCD5 regulation. We recently found that DNAJB1 interacts with PDCD5 and induces the ubiquitin-dependent proteasomal degradation of PDCD5, thereby inhibiting p53-mediated apoptosis. To investigate these novel roles for PDCD5 and DNAJB1, we performed DNAJB1 mapping with PDCD5. PDCD5 specifically binds to the DNAJB1-D5 domain (Δ180-210), which was found to be essential for the stabilization of PDCD5. Further study showed that DNAJB1 post-translationally regulates PDCD5 stability. DNAJB1 ubiquitinated PDCD5 via a ubiquitin-mediated pathway. In human lung A549 cancer cells, DNAJB1 promoted the ubiquitination and degradation of PDCD5 and inhibited p53 activation. However, DNAJB1 knockdown in A549 cells increased the etoposide-induced activation of the p53-mediated apoptosis pathway and repressed cancer cell growth. Because this function was p53 dependent, DNAJB1 depletion increased the expression of p53-targeted apoptosis genes. In conclusion, we screened a novel PDCD5-associating protein, DNAJB1, by yeast two-hybrid screening and provided evidences that DNAJB1 targets PDCD5 to suppress p53-dependent apoptosis of cancer cells. Thus, we identified DNAJB1 as a negative regulator of PDCD5-mediated apoptosis and found that the apoptosis network of PDCD5 regulates cancer cell death.

Histone deacetylase 3 is selectively involved in L3MBTL2-mediated transcriptional repression

MINT‐7719897: HDAC3 (uniprotkb:O15379) physically interacts (MI:0915) with L3MBTL2 (uniprotkb:Q969R5) by two hybrid (MI:0018)