Global gene profiling of (-)-Epigallocatechin-3-gallate (EGCG)-induced neuronal death
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ABSTRACT: Alzheimer’s disease (AD) is the most common form of adult-onset dementia with severe intellectual deterioration and is characterised by the accumulation of the amyloid-β (Aβ) peptides and the presence of hyperphosphorylated microtubule- associated protein, tau. (-)-Epigallocatechin-3-gallate (EGCG) – a polyphenolic catechin found in green tea leaves, not only acts as a proteasome inhibitor, it is also involved in neuroprotection. A total of 7 RNA samples were analyzed. Cultured murine primary cortical neurons were treated with 1uM EGCG for 24h (n=3) in addition to the vehicle control (n=4).
Project description:Alzheimer’s disease (AD) is the most common form of adult-onset dementia with severe intellectual deterioration and is characterised by the accumulation of the amyloid-β (Aβ) peptides and the presence of hyperphosphorylated microtubule- associated protein, tau. (-)-Epigallocatechin-3-gallate (EGCG) – a polyphenolic catechin found in green tea leaves, not only acts as a proteasome inhibitor, it is also involved in neuroprotection.
Project description:We have identified Epigallocatechin Gallate (EGCG) as a potent modulator of microglia function. Our aim was to determine whether EGCG affects the transcriptome of microglia and identify genes and gene sets that may underly the effects of EGCG on microglia function.
Project description:We reported the molecular mechanisms of low combination doses of epigallocatechin-3-gallate and hydroxychavicol (EGCG+HC) in glioma cell lines 1321N1 and LN18. Using high throughput RNA sequencing, combined EGCG+HC exerted its anticancer effect by downregulating the axon guidance process and metabolic pathways, while simultaneously interfering with endoplasmic reticulum unfolded protein response pathway. Furthermore, EGCG+HC exerted its apoptotic effect through the alteration of mitochondrial genes such as MT-CO3 and MT-RNR2 in 1321N1 and LN18 cells respectively. EGCG+HC dynamically altered DYNLL1 alternative splicing expression in 1321N1 and DLD splicing expression in LN18 cell lines.
Project description:The inhibition of DYRK1A (Dual Specificity Tyrosine-Phosphorylation-Regulated Kinase 1A) activity, triplicated in trisomy 21 subjects, has been proved as a promising therapy for Down syndrome. Epigallocatechin-3-gallate (EGCG), a polyphenol of green tea, is an allosteric inhibitor of DYRK1A that showed beneficial pro-cognitive effects in clinical trials with DS individuals. However, EGCG induces several pharmacological effects, and there is no proof that the observed improvements result from DYRK1A inhibition. Besides, the direct consequences of Dyrk1A overexpression are not well defined. We therefore used quantitative proteomics to decipher the proteome and phosphoproteome alterations resulting from Dyrk1A overexpression and its inhibition to get insight into the mechanism of action of EGCG. Towards this aim, we used mice overexpressing Dyrk1A, and compared the hippocampal proteome and phosphoproteome with their wild type counterparts, in basal conditions, and after treatment with EGCG. Moreover, given that the human clinical trials found that the effects of EGCG potentiated the effects of cognitive stimulation, we also included in our study treatment with environmental enrichment and its combination with EGCG. We found that DYRK1A overexpression leads to alterations in protein and phosphoprotein levels of hundreds of proteins, and that the levels of proteins involved in key postsynaptic pathways are restored by the cognitive enhancer treatments, which could help conceiving new therapeutic strategies.
Project description:Epigallocatechin-3-gallate (EGCG), a major active polyphenol of green tea, has been shown to downregulate inflammatory responses in macrophages; however, the underlying mechanism has not been understood. Recently, we identified the 67-kDa laminin receptor (67LR) as a cell-surface EGCG receptor that mediates the anti-cancer action of EGCG at physiologically relevant concentrations (0.1-1 mM). Here we show the molecular basis for the downregulation of TLR4 signal transduction by EGCG at 1 mM in macrophages. Anti-67LR antibody treatment or RNAi-mediated silencing of 67LR resulted in abrogation of the inhibitory action of EGCG on LPS-induced activation of downstream signaling pathways and target gene expressions. Additionally, we found that EGCG reduced the TLR4 expression through 67LR. Interestingly, EGCG induced a rapid upregulation of Tollip protein, a negative regulator of TLR-signaling, and this EGCG action was prevented by 67LR silencing or anti-67LR antibody treatment. RNAi-mediated silencing of Tollip impaired the TLR4 signaling inhibitory activity of EGCG. Taken together, these findings demonstrate that 67LR plays a critical role in mediating anti-inflammatory action of a physiologically relevant EGCG and Tollip expression could be modulated through 67LR. These results provide a new insight into the understanding of negative regulatory mechanisms for TLR4 signaling pathway and consequent inflammatory responses which are implicated in the development and progression of many chronic diseases. We quantified expression profile of 210 inflammatory-relating genes in the 67LR-downregulated cells treated with LPS or/and EGCG by microarray
Project description:The epigenetic regulation of transcription factor genes is critical for T cell lineage specification. A specific methylation pattern within a conserved region of the lineage specifying transcription factor gene FOXP3, the Treg-specific demethylated region (TSDR), is restricted to regulatory T (Treg) cells and required for stable expression of FOXP3 and suppressive function. We analyzed the impact of hypomethylating agents 5-Aza-2`-deoxycytidine and Epigallocatechin-3-gallate (EGCG) on human CD4+CD25- T for generating Treg cell specific DNA methylation pattern within FOXP3-TSDR and inducing functional Treg cells. Gene expression, including lineage specifying transcription factors of the major T cell lineages and their leading cytokines, functional properties and global transcriptome changes were analyzed. 5-Aza-2`-deoxycytidine induced FOXP3-TSDR methylation and expression of Treg cell specific genes FOXP3 and LRRC32. Proliferation of 5-Aza-2´deoxycytidine treated cells was reduced, but they did not show suppressive function. Hypomethylation was not restricted to FOXP3-TSDR and expression of master transcription factors and leading cytokines of Th1 and Th17 cells were induced. EGCG induced global DNA hypomethylation to a lower degree than 5-Aza-2´deoxycitidine, but no relevant hypomethylation within FOXP3-TSDR or expression of Treg cell specific genes. Both DNMT inhibitors did not induce full functional human Treg cells. Although 5-Aza-2`-deoxycytidine treated cells phenotypically appeared to be Treg cells, they did not suppress proliferation of responder cells, which is an essential capability to be used in Treg cell transfer therapy. In this study we analyze the potency of the two hypomethylating agents 5-Aza-2`-deoxycytidine (5-Aza-dC) and Epigallocatechin-3-gallate (EGCG) for in vitro induction of functional Treg cell cells through generation of a specific methylation pattern within FOXP3-TSDR. We analyzed the expression of Treg cell specific genes and for their functional properties from CD4+CD25- T cells. 5-Aza-dC is a derivative of 5-Azacytidine. Both substances are inhibitors of DNA methyltransferases (DNMTs) and used for therapy of patients with myelodysplastic syndrome and acute myeloid leukaemia. In these patients, 5-Azacytidine has been reported to augment regulatory T cell expansion in blood. EGCG is the most abundant catechin of green tea and has been reported to have cardio protective, anti-cancer, anti-infective properties and protective effects on autoimmune diseases. EGCG has also been described as a potent inhibitor of DNMTs and to induce Foxp3 in Jurkat T cell line.
Project description:Epigallocatechin gallate (EGCG), the major green tea polyphenol, has been a subject of global interest as a potential chemopreventive or chemotherapeutic supplement for breast cancer. While on one hand epidemiological studies suggest inverse correlation between green tea consumption and breast cancer risk, investigations using cell culture and animal models of breast carcinogenesis on the other hand have demonstrated antiproliferative, antitumor, anti-invasive and anti-metastatic properties of EGCG. Mechanism of how EGCG affects cell proliferation, apoptosis, migration and cell cycle by affecting the function of a wide range of molecular targets have also been studied. However, the question as to how EGCG impacts on estrogen responsive genes has not been addressed. This issue is of relevance to our notion of EGCG as a potential chemopreventive or chemotherapeutic agent against breast cancer, which is estrogen dependent in majority of the newly diagnosed cases. Here, using the estrogen receptor α (ERα) positive MCF-7 breast cancer cells as a model, we have examined the effect of EGCG on the estrogen regulated genes. MCF7 cells were treated with vehicle (Ethanol) or EGCG in the presence or absence of estrogen for 24hrs. Total RNA was extracted; Cy3 labeled cRNA was hybridized to Genotypic Technology designed Custom Human Whole Genome 8x60k Microarray (Agilent-027114). Median signal intensities were used for the analysis. After background subtraction (normexp) and normalization (quantile) differentially expressed genes were identified using linear models.
Project description:Epigallocatechin gallate (EGCG), the major green tea polyphenol, has been a subject of global interest as a potential chemopreventive or chemotherapeutic supplement for breast cancer. While on one hand epidemiological studies suggest inverse correlation between green tea consumption and breast cancer risk, investigations using cell culture and animal models of breast carcinogenesis on the other hand have demonstrated antiproliferative, antitumor, anti-invasive and anti-metastatic properties of EGCG. Mechanism of how EGCG affects cell proliferation, apoptosis, migration and cell cycle by affecting the function of a wide range of molecular targets have also been studied. However, the question as to how EGCG impacts on estrogen responsive genes has not been addressed. This issue is of relevance to our notion of EGCG as a potential chemopreventive or chemotherapeutic agent against breast cancer, which is estrogen dependent in majority of the newly diagnosed cases. Here, using the estrogen receptor α (ERα) positive MCF-7 breast cancer cells as a model, we have examined the effect of EGCG on the estrogen regulated genes.
Project description:Aging significantly affects intercellular communication between vascular endothelial cells (ECs) and hematopoietic cells, leading to vascular inflammation and age-associated diseases. This study determined how senescent ECs communicate with monocytes, whether extracellular vesicles (EVs) released from senescent ECs affect monocyte functions, and investigated the potential for epigallocatechin-3-gallate (EGCG), a flavonoid in green tea, to reverse these effects. Human umbilical vein endothelial cells (HUVECs) were treated with Etoposide (10 µM, 24h) to induce senescence, followed by EGCG (100 µM, 24h) treatment to evaluate its potential as a senotherapeutic agent. The interaction between ECs and monocytes was analyzed using a co-culture system and direct treatment of monocytes with EC-derived EVs. EGCG reduced senescence-associated phenotypes in ECs, as evidenced by decreased senescence-associated (SA)-β-Gal activity and reversal of Etoposide-induced senescence markers. Monocytes co-cultured with EGCG-treated senescent ECs showed decreased pro-inflammatory responses compared to those co-cultured with untreated senescent ECs. Additionally, senescent ECs produced more EVs than non-senescent ECs. EVs from senescent ECs enhanced lipopolysaccharide (LPS)-induced pro-inflammatory activation of monocytes, whereas EVs from EGCG-treated senescent ECs mitigated this activation, maintaining monocyte activation at normal levels. Our findings reveal that EGCG confers anti-senescent effects via modulation of the senescent EC secretome (including EVs) with the capacity to modify monocyte activation. These findings suggest that EGCG could act as a senotherapeutic agent to reduce vascular inflammation related to aging.