Cyclooxygenase-2 Induced the ?-Amyloid Protein Deposition and Neuronal Apoptosis Via Upregulating the Synthesis of Prostaglandin E2 and 15-Deoxy-?12,14-prostaglandin J2.
ABSTRACT: Elevated levels of cyclooxygenase-2 (COX-2) and prostaglandins (PGs) have been shown to be involved in the pathogenesis of Alzheimer's disease. Analysis of the underlying mechanisms elucidated a function of sequential PGE2 and PGD2 synthesis in regulating ?-amyloid protein (A?) deposition by modulating tumor necrosis factor ? (TNF-?)-dependent presenilin (PS)1/2 activity in COX-2 and APP/PS1 crossed mice. Specifically, COX-2 overexpression accelerates the expression of microsomal PGE synthase-1 (mPGES-1) and lipocalin-type prostaglandin D synthase (L-PGDS), leading to the synthesis of PGE2 and 15-deoxy-?12,14-prostaglandin J2 (15d-PGJ2) in 6-month-old APP/PS1 mice. Consequently, PGE2 has the ability to increase A? production by enhancing the expression of PS1/2 in a TNF-?-dependent manner, which accelerates the cognitive decline of COX-2/APP/PS1 mice. More interestingly, low concentrations of 15d-PGJ2 treatment facilitate the effects of PGE2 on the deposition of A? via TNF-?-dependent PS1/2 mechanisms. In contrast, high concentrations of 15d-PGJ2 treatment inhibit the deposition of A? via suppressing the expression of TNF-?-dependent PS1/2. In this regard, a high concentration of 15d-PGJ2 appears to be a therapeutic agent against Alzheimer's disease. However, the high 15d-PGJ2 concentration treatment induces neuronal apoptosis via increasing the protein levels of Bax, cleaved caspase-3, and DFF45, which further impairs the learning ability of APP/PS1 mice.
Project description:Transferrin (Tf) is an important iron-binding protein postulated to play a key role in iron ion (Fe) absorption via the Tf receptor (TfR), which potentially contributes to the pathogenesis of Alzheimer's disease (AD). However, the role of Tf in AD remains unknown. Using mouse-derived neurons and APP/PS1 transgenic (Tg) mice as model systems, we firstly revealed the mechanisms of APH-1?/1? and presenilin 1 (PS1) upregulation by Fe in prostaglandin (PG) E2- and PGD2-dependent mechanisms. Specifically, Fe stimulated the expression of mPGES-1 and the production of PGE2 and PGD2 via the Tf and TfR system. Highly accumulated PGE2 markedly induced the expression of anterior pharynx-defective-1? and -1? (APH-1?/1?) and PS1 via an EP receptor-dependent mechanism. In contrast, PGD2 suppressed the expression of APH-1?/1? and PS1 via a prostaglandin D2 (DP) receptor-dependent mechanism. As the natural dehydrated product of PGD2, 15d-PGJ2 exerts inhibitory effects on the expression of APH-1?/1? and PS1 in a peroxisome proliferator-activated receptor (PPAR) ?-dependent manner. The expression of APH-1?/1? and PS1 ultimately determined the production and deposition of ?-amyloid protein (A?), an effect that potentially contributes to the pathogenesis of AD.
Project description:Cyclooxygenase-2 (COX-2) has been found to be induced during the early stage of Alzheimer's disease (AD). Using mouse-derived astrocyte and APP/PS1 transgenic (Tg) mice as model systems, we firstly elucidated the mechanisms underlying COX-2 metabolic production including prostaglandin (PG)E2- and PGI2-mediated tumor necrosis factor ? (TNF-?) regulation. Specifically, PGE2 accumulation in astrocyte activated the p38 and JNK/c-Jun signaling pathways via phosphorylation, resulting in TNF-? expression. In contrast, the administration of PGI2 attenuated the effects of PGE2 in stimulating the production of TNF-? by inhibiting the activity of TNF-? promoter and the binding activity of AP1 on the promoter of TNF-?. Moreover, our data also showed that not only A?1-42 oligomers but also A?1-42 fibrils have the ability to involve in mediating the antagonistic effects of PGE2 and PGI2 on regulating the expression of TNF-? via a p38- and JNK/c-Jun-dependent, AP1-transactivating mechanism. Reciprocally, the production of TNF-? finally accelerated the deposition of ?-amyloid protein (A?)1-42 in ?-amyloid plaques (APs), which contribute to the cognitive decline of AD.
Project description:Background:Abnormal upregulation of prostaglandin E2 (PGE2) is considered to be a key oncogenic event in the development and progression of inflammation-associated human colon cancer. It has been reported that 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme catabolizing PGE2, is ubiquitously downregulated in human colon cancer. 15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), a peroxisome proliferator-activated receptor γ ligand, has been shown to have anticarcinogenic activities. In this study, we investigate the effect of 15d-PGJ2 on expression of 15-PGDH in human colon cancer HCT116 cells. Methods:HCT116 cells were treated with 15d-PGJ2 analysis. The expression of 15-PGDH in the treated cells was measured by Western blot analysis and RT-PCR. In addition, the cells were subjected to a 15-PGDH activity assay. To determine which transcription factor(s) and signaling pathway(s) are involved in 15d-PGJ2-induced 15-PGDH expression, we performed a cDNA microarray analysis of 15d-PGJ2-treated cells. The DNA binding activity of AP-1 was measured by an electrophoretic mobility shift assay. To determine whether the AP-1 plays an important role in the 15d-PGJ2-induced 15-PGDH expression, the cells were transfected with siRNA of c-Jun, a major subunit of AP-1. To elucidate the upstream signaling pathways involved in AP-1 activation by 15d-PGJ2, we examined its effect on phosphorylation of Akt by Western blot analysis in the presence or absence of kinase inhibitor. Results:15d-PGJ2 (10 μM) significantly upregulated 15-PGDH expression at the mRNA and protein levels in HCT-116 cells. 15-PGDH activity was also elevated by 15d-PGJ2. We observed that genes encoding C/EBP delta, FOS-like antigen 1, c-Jun, and heme oxygenase-1 (HO-1) were most highly induced in the HCT116 cells following 15d-PGJ2 treatment. 15d-PGJ2 increased the DNA binding activity of AP-1. Moreover, transfection with specific siRNA against c-Jun significantly reduced 15-PGDH expression induced by 15d-PGJ2. 15d-PGJ2 activates Akt and a pharmacological inhibitor of Akt, LY294002, abrogated 15d-PGJ2-induced 15-PGDH expression. We also observed that an inhibitor of HO-1, zinc protoporphyrin IX, also abrogated upregulation of 15-PGDH and down-regulation of cyclooxygenase-2 expression induced by 15d-PGJ2. Conclusions:These finding suggest that 15d-PGJ2 upregulates the expression of 15-PGDH through AP-1 activation in colon cancer HCT116 cells.
Project description:Cyclooxygenase-2 (COX-2) has been recently identified as being involved in the pathogenesis of Alzheimer's disease (AD). However, the role of an important COX-2 metabolic product, prostaglandin (PG) I2, in AD development remains unknown. Using mouse-derived astrocytes as well as APP/PS1 transgenic mice as model systems, we firstly elucidated the mechanisms of interferon ? (IFN?) regulation by PGE2 and PGI2. Specifically, PGE2 accumulation in astrocytes activated the ERK1/2 and NF-?B signaling pathways by phosphorylation, which resulted in IFN? expression. In contrast, the administration of PGI2 attenuated the effects of PGE2 on stimulating the production of IFN? via inhibiting the translocation of NF-?B from the cytosol to the nucleus. Due to these observations, we further studied these prostaglandins and found that both PGE2 and PGI2 increased A?1-42 levels. In detail, PGE2 induced IFN? expression in an A?1-42-dependent manner, whereas PGI2-induced A?1-42 production did not alleviate cells from IFN? inhibition by PGI2 treatment. More importantly, our data also revealed that not only A?1-42 oligomer but also fibrillar have the ability to induce the expression of IFN? via stimulation of NF-?B nuclear translocation in astrocytes of APP/PS1 mice. The production of IFN? finally accelerated the deposition of A?1-42 in ?-amyloid plaques.
Project description:<h4>Background</h4>15-Deoxy-?12,14-prostaglandin J2 (15d-PGJ2), one of the major metabolites from prostaglandin D2 in arachidonic acid metabolic pathway, has potential anti-inflammatory properties. The objective of this study was to explore the effects of 15d-PGJ2-loaded poly(D,L-lactide-co-glycolide) nanocapsules (15d-PGJ2-NC) on inflammatory responses and bone regeneration in local bone defect.<h4>Methods</h4>The study was conducted on 96 Wistar rats from June 2014 to March 2016. Saline, unloaded nanoparticles, free 15d-PGJ2or 15d-PGJ2-NC, were delivered through a collagen vehicle inside surgically created transcortical defects in rat femurs. Interleukin-6 (IL-6), interleukin-1 beta (IL-1?), and tumor necrosis factor-alpha (TNF-?) levels in the surrounding soft tissue were analyzed by Western blot and in the defect by quantitative real-time polymerase chain reaction over 14 days. Simultaneously, bone morphogenetic protein-6 (BMP-6) and platelet-derived growth factor-B (PDGF-B) messenger RNA (mRNA) in the defect were examined. New bone formation and EphrinB2 and osteoprotegerin (OPG) protein expression in the cortical defect were observed by Masson's Trichrome staining and immunohistochemistry over 28 days. Data were analyzed by one-way analysis of variance. Least-significant difference and Dunnett's T3 methods were used with a bilateral P< 0.05.<h4>Results</h4>Application of l5d-PGJ2-NC (100 ?g/ml) in the local bone defect significantly decreased IL-6, IL-1?, and TNF-? mRNA and protein, compared with saline-treated controls (P < 0.05). l5d-PGJ2-NC upregulated BMP-6 and PDGF-B mRNA (P < 0.05). New bone formation was observed in the cortical defect in l5d-PGJ2-NC-treated animals from 7th day onward (P < 0.001). Expression of EphrinB2 and OPG presented early on day 3 and persisted through day 28 in 15d-PGJ2-NC group (P < 0.05).<h4>Conclusion</h4>Stable l5d-PGJ2-NC complexes were prepared that could attenuate IL-6, IL-1?, and TNF-? expression, while increasing new bone formation and growth factors related to bone regeneration.
Project description:A persistent and nonresolving inflammatory response to accumulating A? peptide species is a cardinal feature in the development of Alzheimer's disease (AD). In response to accumulating A? peptide species, microglia, the innate immune cells of the brain, generate a toxic inflammatory response that accelerates synaptic and neuronal injury. Many proinflammatory signaling pathways are linked to progression of neurodegeneration. However, endogenous anti-inflammatory pathways capable of suppressing A?-induced inflammation represent a relatively unexplored area. Here we report that signaling through the prostaglandin-E2 (PGE2) EP4 receptor potently suppresses microglial inflammatory responses to A?42 peptides. In cultured microglial cells, EP4 stimulation attenuated levels of A?42-induced inflammatory factors and potentiated phagocytosis of A?42. Microarray analysis demonstrated that EP4 stimulation broadly opposed A?42-driven gene expression changes in microglia, with enrichment for targets of IRF1, IRF7, and NF-?B transcription factors. In vivo, conditional deletion of microglial EP4 in APPSwe-PS1?E9 (APP-PS1) mice conversely increased inflammatory gene expression, oxidative protein modification, and A? deposition in brain at early stages of pathology, but not at later stages, suggesting an early anti-inflammatory function of microglial EP4 signaling in the APP-PS1 model. Finally, EP4 receptor levels decreased significantly in human cortex with progression from normal to AD states, suggesting that early loss of this beneficial signaling system in preclinical AD development may contribute to subsequent progression of pathology.
Project description:Urinary obstruction is associated with inflammation and oxidative stress, leading to renal dysfunction. Previous studies have shown that 15-deoxy-?12,14-prostaglandin J2 (15d-PGJ2) has both antioxidant and anti-inflammatory effects. Using a unilateral ureteral obstruction (UUO) mouse model, we examined the effects of 15d-PGJ2 on oxidative stress and inflammation in the kidney. Mice were subjected to UUO for 3 days and treated with 15d-PGJ2. Protein and RNA expression were examined using immunoblotting and qPCR. 15d-PGJ2 increased NF-E2-related nuclear factor erythroid-2 (Nrf2) protein expression in response to UUO, and heme oxygenase 1 (HO-1), a downstream target of Nrf2, was induced by 15d-PGJ2. Additionally, 15d-PGJ2 prevented protein carbonylation, a UUO-induced oxidative stress marker. Inflammation, measured by nuclear NF-?B, F4/80, and MCP-1, was increased in response to UUO and further increased by 15d-PGJ2. Renal injury was aggravated by 15d-PGJ2 treatment as measured by kidney injury molecule-1 (KIM-1) and cortical caspase 3 content. No effect of 15d-PGJ2 was observed on renal function in mice subjected to UUO. This study illustrates differentiated functioning of 15d-PGJ2 on inflammation and oxidative stress in response to obstructive nephropathy. High concentrations of 15d-PGJ2 protects against oxidative stress during 3-day UUO in mice; however, it aggravates the associated inflammation.
Project description:An endogenous anticancer agent, 15-deoxy -?12,14-prostaglandin J2 (15d-PGJ2) induces apoptosis in the chemoresistant renal cell carcinoma (RCC). Peroxisome proliferator-activated receptor-? (PPAR?) is a nuclear receptor for 15d-PGJ2, and mediates the cytotoxicity of 15d-PGJ2 in many cancerous cells. However, 15d-PGJ2 induces apoptosis independently of PPAR? in human RCC cell line such as Caki-2. In the present study, we found that 15d-PGJ2 ameliorated the chemoresistance to one of anthracycline antibiotics, doxorubicin, in Caki-2 cells. Doxorubicin alone exhibited weak cytotoxicity at the concentrations effective for other cancer cells such as Hela cells. In addition, it did not activate caspase 3. However, the cytotoxicity of doxorubicin was increased remarkably and accompanied with the caspase- 3 activation in the presence of 15d-PGJ2. Doxorubicin alone damaged plasma membrane, and the combined application of 15d-PGJ2 with doxorubicin increased the membrane permeability slightly. PPAR? was involved in neither the anti-tumor activity nor the synergistic effect of 15d-PGJ2. 15d-PGJ2 induces apoptosis in Caki-2 cells via suppressing the phosphoinositide 3-kinase (PI3K)-Akt pathway. The effect of PI3K inhibitor on the cytotoxicity of doxorubicin was additive, but not synergistic. Although the PI3K inhibitor mimicked the cytotoxicity of 15d-PGJ2, it might not be involved in the synergism between 15d-PGJ2 and doxorubicin. In conclusion, 15d-PGJ2 enhanced the chemosensitivity of doxorubicin via the pathway independent of PPAR? and PI3K.
Project description:15-deoxy-?(12,14)-prostaglandin J2 (15d-PGJ2) is an anti-inflammatory downstream product of the cyclooxygenase enzymes. It has been implicated to play a protective role in a variety of inflammatory mediated diseases, including rheumatoid arthritis, neural damage, and myocardial infarctions. Here we show that 15d-PGJ2 also plays a role in Salmonella infection. Salmonella enterica Typhimurium is a Gram-negative facultative intracellular pathogen that is able to survive and replicate inside phagocytic immune cells, allowing for bacterial dissemination to systemic sites. Salmonella species cause a wide range of morbidity and mortality due to gastroenteritis and typhoid fever. Previously we have shown that in mouse models of typhoid fever, Salmonella infection causes a major perturbation in the prostaglandin pathway. Specifically, we saw that 15d-PGJ2 production was significantly increased in both liver and feces. In this work we show that 15d-PGJ2 production is also significantly increased in macrophages infected with Salmonella. Furthermore, we show that the addition of 15d-PGJ2 to Salmonella infected RAW264.7, J774, and bone marrow derived macrophages is sufficient to significantly reduce bacterial colonization. We also show evidence that 15d-PGJ2 is reducing bacterial uptake by macrophages. 15d-PGJ2 reduces the inflammatory response of these infected macrophages, as evidenced by a reduction in the production of cytokines and reactive nitrogen species. The inflammatory response of the macrophage is important for full Salmonella virulence, as it can give the bacteria cues for virulence. The reduction in bacterial colonization is independent of the expression of Salmonella virulence genes SPI1 and SPI2, and is independent of the 15d-PGJ2 ligand PPAR-?. 15d-PGJ2 also causes an increase in ERK1/2 phosphorylation in infected macrophages. In conclusion, we show here that 15d-PGJ2 mediates the outcome of bacterial infection, a previously unidentified role for this prostaglandin.
Project description:15-deoxy-delta 12,14-prostaglandin J2 (15d-PGJ2) is an anti-inflammatory/anti-neoplastic prostaglandin that functions through covalent binding to cysteine residues of various target proteins. We previously showed that 15d-PGJ2 mediated anti-inflammatory responses are dependent on the translational inhibition through its interaction with eIF4A (Kim et al., 2007). Binding of 15d-PGJ2 to eIF4A specifically blocks the interaction between eIF4G and eIF4A, which leads to the formation of stress granules (SGs), which then cluster mRNAs with inhibited translation. Here, we show that the binding between 15d-PGJ2 and eIF4A specifically blocks the interaction between the MIF4G domain of eIF4G and eIF4A. To reveal the mechanism of this interaction, we used computational simulation-based docking studies and identified that the carboxyl tail of 15d-PGJ2 could stabilize the binding of 15d-PGJ2 to eIF4A through arginine 295 of eIF4A, which is the first suggestion that the 15d-PGJ2 tail plays a physiological role. Interestingly, the putative 15d-PGJ2 binding site on eiF4A is conserved across many species, suggesting a biological role. Our data propose that studying 15d-PGJ2 and its targets may uncover new therapeutic approaches in anti-inflammatory drug discovery.