Sequestration of sorcin by aberrant forms of tau results in the defective calcium homeostasis

Neurofi brillary tangles (NFTs) of microtubule-associated protein tau are a pathological hallmark of Alzheimer's disease (AD). Endoplasmic reticulum (ER) stress has been known to be involved in the pathogenesis of AD. However, the exact role of ER stress in tau pathology has not yet been clearly elucidated. In present study, the possible relationship between tau pathology and ER stress was examined in terms of sorcin, which is a calcium binding protein and plays an important role in calcium homeostasis. Our previous yeast two hybrid study showed that sorcin is a novel tau interacting protein. Caspase-3-cleaved tau (T4C3) showed significantly increased tau-sorcin interaction compared to wild type tau (T4). Thapsigargin-induced ER stress and co-expression of constitutively active GSK3β (GSK3β-S9A) also exhibited significantly increased tau-sorcin interactions. T4C3-expressing cells showed potentiated thapsigargin-induced apoptosis and disruption of intracellular calcium homeostasis compared to T4-expressing cells. Overexpression of sorcin signifi cantly attenuated thapsigargin-induced apoptosis and disruption of calcium homeostasis. In contrary, siRNA-mediated knock-down of sorcin showed significantly increased thapsigargin-induced apoptosis and disruption of calcium homeostasis. These data strongly suggest that sequestration of sorcin by aberrant forms of tau compromises the function of sorcin, such as calcium homeostasis and cellular resistance by ER stress, which may consequently result in the contribution to the progression of AD.

Quercetin-3-O-β-D-Glucuronide Suppresses Lipopolysaccharide-Induced JNK and ERK Phosphorylation in LPS-Challenged RAW264.7 Cells

Quercetin, a flavonol, has been reported to exhibit a wide range of biological properties including anti-oxidant and anti-inflammatory activities. However, pharmacological properties of quercetin-3-O-β-D-glucuronide (QG), a glycoside derivative of quercetin, have not been extensively examined. The objective of this study is to elucidate the anti-inflammatory property and underlying mechanism of QG in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells in comparison with quercetin. QG significantly suppressed LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and PGE2, and pro-inflammatory protein expressions of iNOS and COX-2. To elucidate the underlying mechanism of the anti-inflammatory property of QG, involvement of MAPK signaling pathways was examined. QG significantly attenuated LPS-induced activation of JNK and ERK in concentration-dependent manners with a negligible effect on p38. In conclusion, the present study demonstrates QG exerts anti-inflammatory activity through the suppression of JNK and ERK signaling pathways in LPS-challenged RAW264.7 macrophage cells.

3,4,5-Trihydroxycinnamic Acid Inhibits LPS-Induced iNOS Expression by Suppressing NF-kappaB Activation in BV2 Microglial Cells

Although various derivatives of caffeic acid have been reported to possess a wide variety of biological activities such as neuronal protection against excitotoxicity and anti-inflammatory property, the biological activity of 3,4,5-trihydroxycinnamic acid (THC), a derivative of hydroxycinnamic acids, has not been clearly examined. The objective of the present study is to evaluate the anti-inflammatory effects of THC on lipopolysaccharide (LPS)-stimulated BV2 microglial cells. THC significantly suppressed LPS-induced excessive production of nitric oxide (NO) and expression of iNOS, which is responsible for the production of iNOS. THC also suppressed LPS-induced overproduction of pro-inflammatory cytokines such as IL-1beta and TNF-alpha in BV2 microgilal cells. Furthermore, THC significantly suppressed LPS-induced degradation of IkappaB, which retains NF-kappaB in the cytoplasm. Therefore, THC attenuated nuclear translocation of NF-kappaB, a major pro-inflammatory transcription factor. Taken together, the present study for the first time demonstrates that THC exhibits anti-inflammatory activity through the suppression of NF-kappaB transcriptional activation in LPS-stimulated BV2 microglial cells.

Suppression of Autophagy and Activation of Glycogen Synthase Kinase 3beta Facilitate the Aggregate Formation of Tau

Neurofibrillary tangle (NFT) is a characteristic hallmark of Alzheimer's disease. GSK3beta has been reported to play a major role in the NFT formation of tau. Dysfunction of autophagy might facilitate the aggregate formation of tau. The present study examined the role of GSK3beta-mediated phosphorylation of tau species on their autophagic degradation. We transfected wild type tau (T4), caspase-3-cleaved tau at Asp421 (T4C3), or pseudophosphorylated tau at Ser396/Ser404 (T4-2EC) in the presence of active or enzyme-inactive GSK3beta. Trehalose and 3-methyladenine (3-MA) were used to enhance or inhibit autophagic activity, respectively. All tau species showed increased accumulation with 3-MA treatment whereas reduced with trehalose, indicating that tau undergoes autophagic degradation. However, T4C3 and T4-2EC showed abundant formation of oligomers than T4. Active GSK3beta in the presence of 3-MA resulted in significantly increased formation of insoluble tau aggregates. These results indicate that GSK3beta-mediated phosphorylation and compromised autophagic activity significantly contribute to tau aggregation.

Thrombin-induced Migration and Matrix Metalloproteinase-9 Expression Are Regulated by MAPK and PI3K Pathways in C6 Glioma Cells

Glioblastoma multiforme is one of the most common and aggressive tumors in central nervous system. It often possesses characteristic necrotic lesions with hemorrhages, which increase the chances of exposure to thrombin. Thrombin has been known as a regulator of MMP-9 expression and cancer cell migration. However, the effects of thrombin on glioma cells have not been clearly understood. In the present study, influences of thrombin on glioma cell migration were examined using Boyden chamber migration assay and thrombin-induced changes in MMP-9 expression were measured using zymography, semi-quantitative RT-PCR, and Western blotting. Furthermore, underlying signaling pathways by which thrombin induces MMP-9 expression were examined. Thrombin-induced migration and MMP-9 expression were significantly potentiated in the presence of wortmannin, a PI3K inhibitor, whereas MAPK inhibitors suppressed thrombin-induced migration and MMP-9 expression in C6 glioma cells. The present data strongly demonstrate that MAPK and PI3K pathways evidently regulate thrombin-induced migration and MMP-9 expression of C6 glioma cells. Therefore, the control of these pathways might be a beneficial therapeutic strategy for treatment of invasive glioblastoma multiforme.

Generation accumulation of murine ovarian genes in offspring exposed to microwave in uterus / 대한산부인과학회지

OBJECTIVE: The aim of this study was to evaluate generational accumulation of murine fetal ovarian genes following prenatal exposure to 1.765-GHz microwave radiation. METHODS: A 1.765-GHz microwave generator was used. Twenty pregnant ICR mice were divided into two groups: the microwave-exposed experimental (irradiated) group, and the sham-exposed (sham) group. On the fifth day post-mating, dam mice were exposed to microwave irradiation in the insulated cage for 8 hours each day. The remaining mice were treated in the same way. Second generation mice were raised for 8 weeks then classified into four groups for examination. We removed the neonatal ovaries on the seventh day after the third delivery. We investigated the expression of six genes in the ovaries: Tnfaip 8, TNFsf 12, Cfd, CCL 11, Zfp 74, and Brd 3. Real time reverse transcription-polymerase chain reaction was performed using total RNA extracted from the removed ovaries. RESULTS: In the third-generation offspring, we detected some differences in ovarian gene expression between the first group and the fourth. Expression of CCL 11, and TNFsf 12 was decreased in the first group compared to the fourth group. Expression of Tnfaip 8, brd 3, Cfd, and Zfp 74 was higher in the first group than in the fourth group. We found differing results when we compared ovarian gene expression in mice of the second generation with those of the third. CONCLUSION: The results suggest that there is no generational accumulation of murine ovarian genes in offspring exposed to 1.765-GHz microwaves in the uterus.

Celecoxib Attenuates Kainic Acid-induced Neuronal Cell Death Through Suppression of Microglial c-Jun N-terminal Kinase Phosphorylation

In the present study, neuroprotective property of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, and its underlying mechanism were examined in the animal model of kainic acid (KA)-induced excitotoxicity. KA, administered intracerebroventricularly (i.c.v.), induced marked neuronal cell death with concurrent microglial activation and subsequent induction of inducible nitric oxide synthase (iNOS) in the hippocampus. Histopathological analysis demonstrated that celecoxib (100 mg/kg), pre-treated 1 hr before or post-treated 2 hr after KA i.c.v. injection, significantly attenuated KA-induced death of pyramidal neurons in CA3 region. Celecoxib obviously suppressed KA-induced microglial activation and subsequent iNOS expression. KA- induced phosphorylation of c-Jun N-terminal kinases (JNK) was attenuated with celecoxib treatments. The results of the present study demonstrate that suppression of JNK phosphorylation by celecoxib contributes to its neuroprotective action against KA-induced excitotoxicity suggesting that celecoxib may be a potentially valuable in the treatment of acute brain pathologies associated with excitotoxic neuronal damage such as epilepsy, stroke, and traumatic brain injury.

Microarray analysis of gene expression in mice ovaries exposed to a 1.765 GHz microwave in utero / 대한산부인과학회지

OBJECTIVE: The aim of this study was to evaluate the effects on murine fetal ovarian gene expression of prenatal exposure to 1.765 GHz of microwave irradiation. METHODS:Ten pregnant ICR mice were divided into two groups. At 5th days after mating, dam mice were exposed to microwave (SAR: 0.38~1.71 W/kg) in the insulated cage for 8 hours each day. The remaining mice were treated in the same way. Neonatal ovaries were removed for study 7 days after delivery. Microarray analysis was performed using total RNA extracted from the removed ovaries. We investigated the differences in ovarian gene expression between the groups. SPSS 12.0 was used for statistical analysis. P<0.05 was considered to be statistically significant. RESULTS: The mean birth weight of the offspring in the irradiated group was significantly lower than that in the sham group (1.54+/-.22 g vs. 1.60+/-.21 g, P=0.012). The mean number of offspring per pregnancy in the irradiated group was significantly higher than in the sham group (13.60+/-.70 vs. 11.40+/-.17, P=0.009). We detected that in the irradiated ovaries, 14 genes were expressed at levels 2-fold higher than in the sham ovaries and 74 genes were expressed at levels 2-fold lower than in the sham ovaries. CONCLUSION: We found differences in fetal ovarian gene expression between the irradiated and sham groups. In the irradiated group, the Tnfaip8, TNFsf 12, Cfd, CCL 11, and Zfp74 genes were down-regulated and the Brd 3 gene was up-regulated.

Microarray analysis of gene expression in mice ovaries exposed to a 1.765 GHz microwave in utero / 대한산부인과학회지

OBJECTIVE: The aim of this study was to evaluate the effects on murine fetal ovarian gene expression of prenatal exposure to 1.765 GHz of microwave irradiation. METHODS:Ten pregnant ICR mice were divided into two groups. At 5th days after mating, dam mice were exposed to microwave (SAR: 0.38~1.71 W/kg) in the insulated cage for 8 hours each day. The remaining mice were treated in the same way. Neonatal ovaries were removed for study 7 days after delivery. Microarray analysis was performed using total RNA extracted from the removed ovaries. We investigated the differences in ovarian gene expression between the groups. SPSS 12.0 was used for statistical analysis. P<0.05 was considered to be statistically significant. RESULTS: The mean birth weight of the offspring in the irradiated group was significantly lower than that in the sham group (1.54+/-.22 g vs. 1.60+/-.21 g, P=0.012). The mean number of offspring per pregnancy in the irradiated group was significantly higher than in the sham group (13.60+/-.70 vs. 11.40+/-.17, P=0.009). We detected that in the irradiated ovaries, 14 genes were expressed at levels 2-fold higher than in the sham ovaries and 74 genes were expressed at levels 2-fold lower than in the sham ovaries. CONCLUSION: We found differences in fetal ovarian gene expression between the irradiated and sham groups. In the irradiated group, the Tnfaip8, TNFsf 12, Cfd, CCL 11, and Zfp74 genes were down-regulated and the Brd 3 gene was up-regulated.