MiR-1246 Promotes Metastasis and Invasion of A549 cells by Targeting GSK-3β‒Mediated Wnt/β-Catenin Pathway / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: MicroRNAs (miRNAs) are a group of small non-coding RNAs involved in different cancers, including lung cancer. Here, we aim to investigate the expression profiles of circulating miRNAs and their roles contributed to the progress of lung cancer. MATERIALS AND METHODS: The levels of circulating miRNA in lung cancer patients were investigated by miRNAs assay. Then we predicted the target genes of aberrantly expressing miRNAs by searching genetic databases. Based on the A549 cells transfected with miR-1246 mimics or miR-1246 inhibitor,we further measured the roles of miR-1246 involving in the epithelial-mesenchymal transition (EMT), migration and invasion capacities of lung cancer cells in vitro. Finally, we detected the effects of miR-1246 on glycogen synthase kinase-3β (GSK-3β)/β-catenin pathway by immunofluorescence and Western blot, respectively. RESULTS: We identified that 14 miRNAs were aberrantly expressed in the serum of lung cancer patients. Among them, miR-1246 was the most up-regulated. The cell assays indicated that miR-1246 significantly increased the migration and invasion capabilities of A549 lung cancer cells. Meanwhile, immunofluorescence analysis revealed that miR-1246 promoted EMT process of A549 cells accompanying with decreasing E-cadherin expression, while increasing vimentin and transforming growth factor β (TGF-β) expression. Furthermore, an online tool predicated that miR-1246 might bind to 3′-untranslated region of GSK-3β, which was confirmed by overexpression and knockdown of miR-1246 assays. CONCLUSION: Taken together, the study illustrates that miR-1246 regulates Wnt/β-catenin pathway through targeting GSK-3β/β-catenin, which partly contributing to tumor metastasis. MiR-1246 may play an essential role in the diagnosis and therapeutic of lung cancer.

7,8,4′-Trihydroxyisoflavone, a Metabolized Product of Daidzein, Attenuates 6-Hydroxydopamine-Induced Neurotoxicity in SH-SY5Y Cells

Daidzein isolated from soybean (Glycine max) has been widely studied for its antioxidant and anti-inflammatory activities. However, the protective effects of 7,8,4′-trihydroxyisoflavone (THIF), a major metabolite of daidzein, on 6-hydroxydopamine (OHDA)-induced neurotoxicity are not well understood. In the current study, 7,8,4′-THIF significantly inhibited neuronal cell death and lactate dehydrogenase (LDH) release induced by 6-OHDA in SH-SY5Y cells, which were used as an in vitro model of Parkinson's disease (PD). Moreover, pretreatment with 7,8,4′-THIF significantly increased the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) and decreased malondialdehyde (MDA) activity in 6-OHDA-induced SH-SY5Y cells. In addition, 7,8,4′-THIF significantly recovered 6-OHDA-induced cleaved caspase-3, cleaved caspase-9, cleaved poly-ADP-ribose polymerase (PARP), increased Bax, and decreased Bcl-2 levels. Additionally, 7,8,4′-THIF significantly restored the expression levels of phosphorylated c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 1/2 (ERK 1/2), phosphatidylinositol 3-kinases (PI3K)/Akt, and glycogen synthase kinase-3 beta (GSK-3β) in 6-OHDA-induced SH-SY5Y cells. Further, 7,8,4′-THIF significantly increased the reduced tyrosine hydroxylase (TH) level induced by 6-OHDA in SH-SY5Y cells. Collectively, these results suggest that 7,8,4′-THIF protects against 6-OHDA-induced neuronal cell death in cellular PD models. Also, these effects are mediated partly by inhibiting activation of the MAPK and PI3K/Akt/GSK-3β pathways.

PI3K-Akt-Wnt Pathway Is Implicated in Exercise-Induced Improvement of Short-term Memory in Cerebral Palsy Rats / 대한배뇨장애요실금학회지

PURPOSE: Maternal lipopolysaccharide (LPS) injection induces neurodevelopmental disorders, such as cerebral palsy. Exercise activates phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt) signaling pathway that enhances neurogenesis. Wnt ligands are also implicated in the hippocampal neurogenesis and synaptic plasticity. Glycogen synthase kinase-3β (GSK-3β) is a downstream molecule of Akt, and GSK-3β is known to modulate hippocampal neurogenesis negatively. METHODS: Cerebral palsy was made by maternal LPS-injection. On the 5 weeks after birth, treadmill running was applied to the rat pups of the exercise groups, for 30 minutes, 5 times a week during 6 weeks. RESULTS: Treadmill running alleviated short-term memory impairments of the cerebral palsy rat pups. Hippocampal cell proliferation was increased and hippocampal apoptosis was suppressed by treadmill running in the cerebral palsy rat pups. Hippocampal phosphorylated-PI3K/PI3K ratio, phosphorylated-Akt/Akt ratio, and Wnt expression were enhanced by treadmill running in the cerebral palsy rat pups. In contrast, hippocampal phosphorylated-GSK-3β/GSK-3β ratio and β-catenin expression were suppressed by treadmill running in the cerebral palsy rat pups. CONCLUSIONS: The results of this study showed that short-term memory improvement due to treadmill running in cerebral palsy occurs via activation of the PI3K-Akt-Wnt pathway.

β-arrestin2 Affects Cardiac Progenitor Cell Survival through Cell Mobility and Tube Formation in Severe Hypoxia

BACKGROUND AND OBJECTIVES: β-arrestin2 (β-arr2) basically regulates multiple signaling pathways in mammalian cells by desensitization and internalization of G-protein coupled receptors (GPCRs). We investigated impacts of β-arr2 on survival, mobility, and tube formation of cardiac progenitor cells (CPCs) obtained from wild-type (WT) mouse (CPC-WT), and β-arr2 knock-out (KO) mouse (CPC-KO) cultured in presence or absence of serum and oxygen as non-canonical roles in GPCR system. METHODS: CPCs were cultured in Dulbecco's Modified Eagle Medium/Nutrient Mixture F-12 -based media containing fetal bovine serum and growth factors. Survival of 2 types of CPCs in hypoxia and/or serum deprivation was measured by fluorescence-activated cell sorting. Wound healing ability, and tube formation ability on Matrigel of 2 kinds of CPCs were compared in normoxic and hypoxic cultures. Protein expression related to survival and mobility were measured with the Western blot for each culture conditions. RESULT: CPC-KO showed significantly worse mobility in the wound healing assay and in tube formation on Matrigel especially in hypoxic culture than did the CPC-WT. Also, CPC-KO showed significantly higher apoptosis fraction in both normoxic and hypoxic cultures than did the CPC-WT. Expression of proteins associated with cell survival and mobility, e.g., protein kinase B (Akt), β-catenin, and glycogen synthase kinase-3β (GSK-3β) was significantly worse in CPC-KO. CONCLUSIONS: The CPC-KO had significantly worse cell mobility, tube formation ability, and survival than the CPC-WT, especially in the hypoxic cultures. Apparently, β-arr2 is important on CPC survival by means of mobility and tube formation in myocardial ischemia.

Potential involvement of glycogen synthase kinase (GSK)-3β in a rat model of multiple sclerosis: evidenced by lithium treatment / 대한해부학회지

Glycogen synthase kinase (GSK)-3β has been known as a pro-inflammatory molecule in neuroinflammation. The involvement of GSK-3β remains unsolved in acute monophasic rat experimental autoimmune encephalomyelitis (EAE). The aim of this study was to evaluate a potential role of GSK-3β in central nervous system (CNS) autoimmunity through its inhibition by lithium. Lithium treatment significantly delayed the onset of EAE paralysis and ameliorated its severity. Lithium treatment reduced the serum level of pro-inflammatory tumor necrosis factor a but not that of interleukin 10. Western blot analysis showed that the phosphorylation of GSK-3β (p-GSK-3β) and its upstream factor Akt was significantly increased in the lithium-treated group. Immunohistochemical examination revealed that lithium treatment also suppressed the activation of ionized calcium binding protein-1-positive microglial cells and vascular cell adhesion molecule-1 expression in the spinal cords of lithium-treated EAE rats. These results demonstrate that lithium ameliorates clinical symptom of acute monophasic rat EAE, and GSK-3 is a target for the suppression of acute neuroinflammation as far as rat model of human CNS disease is involved.

Static magnetic fields promote osteoblastic/cementoblastic differentiation in osteoblasts, cementoblasts, and periodontal ligament cells

PURPOSE: Although static magnetic fields (SMFs) have been used in dental prostheses and osseointegrated implants, their biological effects on osteoblastic and cementoblastic differentiation in cells involved in periodontal regeneration remain unknown. This study was undertaken to investigate the effects of SMFs (15 mT) on the osteoblastic and cementoblastic differentiation of human osteoblasts, periodontal ligament cells (PDLCs), and cementoblasts, and to explore the possible mechanisms underlying these effects. METHODS: Differentiation was evaluated by measuring alkaline phosphatase (ALP) activity, mineralized nodule formation based on Alizarin red staining, calcium content, and the expression of marker mRNAs assessed by reverse transcription polymerase chain reaction (RT-PCR). Signaling pathways were analyzed by western blotting and immunocytochemistry. RESULTS: The activities of the early marker ALP and the late markers matrix mineralization and calcium content, as well as osteoblast- and cementoblast-specific gene expression in osteoblasts, PDLCs, and cementoblasts were enhanced. SMFs upregulated the expression of Wnt proteins, and increased the phosphorylation of glycogen synthase kinase-3β (GSK-3β) and total β-catenin protein expression. Furthermore, p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB) pathways were activated. CONCLUSIONS: SMF treatment enhanced osteoblastic and/or cementoblastic differentiation in osteoblasts, cementoblasts, and PDLCs. These findings provide a molecular basis for the beneficial osteogenic and/or cementogenic effect of SMFs, which could have potential in stimulating bone or cementum formation during bone regeneration and in patients with periodontal disease.

Lithium ameliorates rat spinal cord injury by suppressing glycogen synthase kinase-3β and activating heme oxygenase-1 / 대한해부학회지

Glycogen synthase kinase (GSK)-3β and related enzymes are associated with various forms of neuroinflammation, including spinal cord injury (SCI). Our aim was to evaluate whether lithium, a non-selective inhibitor of GSK-3β, ameliorated SCI progression, and also to analyze whether lithium affected the expression levels of two representative GSK-3β–associated molecules, nuclear factor erythroid 2-related factor-2 (Nrf-2) and heme oxygenase-1 (HO-1) (a target gene of Nrf-2). Intraperitoneal lithium chloride (80 mg/kg/day for 3 days) significantly improved locomotor function at 8 days post-injury (DPI); this was maintained until 14 DPI (P<0.05). Western blotting showed significantly increased phosphorylation of GSK-3β (Ser9), Nrf-2, and the Nrf-2 target HO-1 in the spinal cords of lithium-treated animals. Fewer neuropathological changes (e.g., hemorrhage, inflammatory cell infiltration, and tissue loss) were observed in the spinal cords of the lithium-treated group compared with the vehicle-treated group. Microglial activation (evaluated by measuring the immunoreactivity of ionized calcium-binding protein-1) was also significantly reduced in the lithium-treated group. These findings suggest that GSK-3β becomes activated after SCI, and that a non-specific enzyme inhibitor, lithium, ameliorates rat SCI by increasing phosphorylation of GSK-3β and the associated molecules Nrf-2 and HO-1.

Effects of chronic alcohol exposure on ischemia–reperfusion-induced acute kidney injury in mice: the role of β-arrestin 2 and glycogen synthase kinase 3

Little is known about the effects of chronic alcohol intake on the outcome of acute kidney injury (AKI). Hence, we examined the effects of chronic alcohol intake on the development of renal fibrosis following AKI in an animal model of bilateral renal ischemia–reperfusion (IR) injury. We first found that chronic alcohol exposure exacerbated bilateral IR-induced renal fibrosis and renal function impairment. This phenomenon was associated with increased bilateral IR-induced extracellular matrix deposition and an increased myofibroblast population as well as increased bilateral IR-induced expression of fibrosis-related genes in the kidneys. To explore the mechanisms underlying this phenomenon, we showed that chronic alcohol exposure enhanced β-arrestin 2 (Arrb2) expression and Akt and glycogen synthase kinase-3 (GSK3)β activation in the kidneys. Importantly, pharmacological GSK3 inhibition alleviated bilateral IR-induced renal fibrosis and renal function impairment. Furthermore, we demonstrated that Arrb2(−/−) mice exhibited resistance to IR-induced renal fibrosis and renal function impairment following chronic alcohol exposure, and these effects were associated with attenuated GSK3β activation in the kidneys. Taken together, our results suggest that chronic alcohol exposure may potentiate AKI via β-arrestin 2/Akt/GSK3β-mediated signaling in the kidney.

Neural Stem Cell Death Mechanisms Induced by Amyloid Beta

BACKGROUND AND PURPOSE: Amyloid beta (Aβ) is the main component of amyloid plaques, which are deposited in the brains of patients with Alzheimer's disease (AD). Biochemical and animal studies support the central role of Aβ in AD pathogenesis. Despite several investigations focused on the pathogenic mechanisms of Aβ, it is still unclear how Aβ accumulates in the central nervous system and subsequently initiates the disease at the cellular level. In this study, we investigated the pathogenic mechanisms of Aβ using proteomics and antibody microarrays. METHODS: To evaluate the effect of Aβ on neural stem cells (NSCs), we treated primary cultured cortical NSCs with several doses of Aβ for 48 h. A 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, trypan blue staining, and bromodeoxyuridine cell proliferation assay were performed. We detected several intracellular proteins that may be associated with Aβ by proteomics and Western blotting analysis. RESULTS: Various viability tests showed that Aβ decreased NSCs viability and cell proliferation in a concentration-dependent manner. Aβ treatment significantly decreased lactate dehydrogenase B, high-mobility group box 1, aldolase C, Ezrin, and survival signals including phosphorylated phosphoinositide 3-kinase, Akt, and glycogen synthase kinase-3β. CONCLUSIONS: These results suggest that several factors determined by proteomics and Western blot hold the clue to Aβ pathogenesis. Further studies are required to investigate the role of these factors.

Cytotoxic Effects of Gallic Acid and its Derivatives Against HIV-I-infected Microglia

In the previous study, we found that flavonoids and ginsenosides exhibited high eliminate rates of human immunodeficiency virus type 1 (HIV-1) D3-transfected macrophages. Based on these findings, here we synthesized the derivatives of gallic acid, including methyl gallate, methyl 4-O-methyl gallate, methyl 3,4-O-dimethyl gallate, and methyl 3,4,5-O-trimethyl gallate and measured their cellular toxic effects against HIV-1-infected macrophages. Of these, treatment with methyl 4-O-methyl gallate in the presence of lipopolysaccharide (LPS) and cycloheximide (CHX) most effectively eliminated HIV-1-transfected cytoprotective human microglial CHME5 cells and HIV-1-D3-infected human primary macrophages. Furthermore, these strongly inhibited LPS/CHX-induced phosphorylation of phosphoinositide 3-kinase (PI3K), pyruvate dehydrogenase lipoamide kinase isozyme 1 (PDK1), Akt, and glycogen synthase kinase-3β (GSK-3β) in the Tat-transfected cells and HIV-1-D3-infected human primary macrophages. These findings suggest that methyl 4-O-methyl gallate may be a promising candidate for eliminating HIV-1 infected macrophages by blocking PI3K/Akt signaling pathway.

The Anti-Inflammatory Activity of Eucommia ulmoides Oliv. Bark. Involves NF-κB Suppression and Nrf2-Dependent HO-1 Induction in BV-2 Microglial Cells

In the present study, we investigated the anti-inflammatory properties of Eucommia ulmoides Oliv. Bark. (EUE) in lipopolysaccharide (LPS)-stimulated microglial BV-2 cells and found that EUE inhibited LPS-mediated up-regulation of pro-inflammatory response factors. In addition, EUE inhibited the elevated production of pro-inflammatory cytokines, mediators, and reactive oxygen species (ROS) in LPS-stimulated BV-2 microglial cells. Subsequent mechanistic studies revealed that EUE suppressed LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs), phosphoinositide-3-kinase (PI3K)/Akt, glycogen synthase kinase-3β (GSK-3β), and their downstream transcription factor, nuclear factor-kappa B (NF-κB). EUE also blocked the nuclear translocation of NF-κB and inhibited its binding to DNA. We next demonstrated that EUE induced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and upregulated heme oxygenase-1 (HO-1) expression. We determined that the significant up-regulation of HO-1 expression by EUE was a consequence of Nrf2 nuclear translocation; furthermore, EUE increased the DNA binding of Nrf2. In contrast, zinc protoporphyrin (ZnPP), a specific HO-1 inhibitor, blocked the ability of EUE to inhibit NO and PGE2 production, indicating the vital role of HO-1. Overall, our results indicate that EUE inhibits pro-inflammatory responses by modulating MAPKs, PI3K/Akt, and GSK-3β, consequently suppressing NF-κB activation and inducing Nrf2-dependent HO-1 activation.

Glycogen synthase kinase 3β and cyclin D1 expression in cervical carcinogenesis

OBJECTIVE: Glycogen synthase kinase 3β (GSK3β) is a pluripotent protein kinase involved in the development of cancers through regulation of numerous oncogenic molecules. Cyclin D1, an important regulator of G1 to S phase transition in various cells, is one of target proteins that GSK3β regulate. Our objective was to assess the expression of GSK3β and cyclin D1 in cervical neoplasm of different histologic grades and to identify their correlation in cervical carcinogenesis. METHODS: Immunohistochemical analysis of GSK3β and cyclin D1 was performed in a total of 137 patients with 12 normal, 62 cervical intraepithelial neoplasia (CIN) (31 CIN1 and 31 CIN3) and 63 invasive cancers including 56 squamous cell carcinomas and 7 adenocarcinomas. RESULTS: The expression of GSK3β increased in parallel with the lesion grade, while that of cyclin D1 decreased with severity of the lesion (P<0.001). There was a significant inverse correlation between GSK3β and cyclin D1 expression in overall cervical neoplasia (Φ=-0.413, P<0.001). GSK3β expression was higher in squamous cell carcinoma than in adenocarcinoma (P=0.049). CONCLUSION: These results suggest that the expressional increase in GSK3β plays a role in cervical carcinogenesis and has inverse correlation with cyclin D1 expression in this process. In addition, GSK3β expression appears to be associated with the histologic type of cervical cancer, especially squamous cell carcinoma.

Expression and clinical significance of nuclear factor κB/B cell lymphoma-2 signal pathway and glycogen synthase kinase 3β in oral squamous cell carcinoma / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aims to examine the expression of nuclear factor κB (NF-κB)/B cell lymphoma-2 (Bcl-2) signal pathway and glycogen synthase kinase 3β (GSK-3β) in oral squamous cell carcinoma (OSCC) and provide references for the early diagnosis and prognosis evaluation of OSCC.</p><p><b>METHODS</b>A total of 55 cases of OSCC and 10 cases of paracan- cerous mucosa were examined in this study. Their expressions of GSK-3β, NF-κB and Bcl-2 were detected using the SP me- thod immunohistochemistry. The correlation between their expression in OSCC and the clinical and pathological peculiarity of OSCC was analyzed.</p><p><b>RESULTS</b>The positive expression of GSK-3β, NF-κB, and Bcl-2 in OSCC were significantly higher than that in paracancerous mucosa (P < 0.01). The expression of GSK-3β, NF-κB, and Bcl-2 had no obvious relationship with patient's age, sex, and clinical stages of the disease (P > 0.05). The expression of Bcl-2 was significantly correlated with the degree of tumor differentiation (P < 0.05), whereas the expression of GSK-3β and NF-κB in OSCC had no obvious relation- ship with the degree of tumor differentiation (P > 0.05). Strong positive correlations were observed among the expressions of GSK-3β, NF-κB, and Bcl-2 (P < 0.05).</p><p><b>CONCLUSION</b>The positive expression of GSK-3β, NF-κB, and Bcl-2 in OSCC are sig- nificantly higher than that in paracancerous mucosa. Detecting GSK-3β, NF-κB, and Bcl-2 in OSCC may have implications in the early diagnosis and prognosis evaluation of OSCC.</p>

Atractylochromene Is a Repressor of Wnt/beta-Catenin Signaling in Colon Cancer Cells

Wnt/beta-catenin signaling pathway was mutated in about 90% of the sporadic and hereditary colorectal cancers. The abnormally activated beta-catenin increases the cancer cell proliferation, differentiation and metastasis through increasing the expression of its oncogenic target genes. In this study, we identified an inhibitor of beta-catenin dependent Wnt pathway from rhizomes of Atractylodes macrocephala Koidzumi (Compositae). The active compound was purified by activity-guided purification and the structure was identified as 2,8-dimethyl-6-hydroxy-2-(4-methyl-3-pentenyl)-2H-chromene (atractylochromene, AC). AC suppressed beta-catenin/T-cell factor transcriptional activity of HEK-293 reporter cells when they were stimulated by Wnt3a or inhibitor of glycogen synthase kinase-3beta. AC down-regulated the nuclear level of beta-catenin through the suppression of galectin-3 mediated nuclear translocation of beta-catenin in SW-480 colon cancer cells. Furthermore, AC inhibits proliferation of colon cancer cell. Taken together, AC from A. macrocephala might be a potential chemotherapeutic agent for the prevention and treatment of human colon cancer.

Cloning and Molecular Characterization of beta-1,3-Glucan Synthase from Sparassis crispa

A beta-glucan synthase gene was isolated from the genomic DNA of polypore mushroom Sparassis crispa, which reportedly produces unusually high amount of soluble beta-1,3-glucan (beta-glucan). Sequencing and subsequent open reading frame analysis of the isolated gene revealed that the gene (5,502 bp) consisted of 10 exons separated by nine introns. The predicted mRNA encoded a beta-glucan synthase protein, consisting of 1,576 amino acid residues. Comparison of the predicted protein sequence with multiple fungal beta-glucan synthases estimated that the isolated gene contained a complete N-terminus but was lacking approximately 70 amino acid residues in the C-terminus. Fungal beta-glucan synthases are integral membrane proteins, containing the two catalytic and two transmembrane domains. The lacking C-terminal part of S. crispa beta-glucan synthase was estimated to include catalytically insignificant transmembrane alpha-helices and loops. Sequence analysis of 101 fungal beta-glucan synthases, obtained from public databases, revealed that the beta-glucan synthases with various fungal origins were categorized into corresponding fungal groups in the classification system. Interestingly, mushrooms belonging to the class Agaricomycetes were found to contain two distinct types (Type I and II) of beta-glucan synthases with the type-specific sequence signatures in the loop regions. S. crispa beta-glucan synthase in this study belonged to Type II family, meaning Type I beta-glucan synthase is expected to be discovered in S. crispa. The high productivity of soluble beta-glucan was not explained but detailed biochemical studies on the catalytic loop domain in the S. crispa beta-glucan synthase will provide better explanations.

Anti-diabetic effects of benfotiamine on an animal model of type 2 diabetes mellitus / 대한수의학회지

Although benfotiamine has various beneficial anti-diabetic effects, the detailed mechanisms underlying the impact of this compound on the insulin signaling pathway are still unclear. In the present study, we evaluated the effects of benfotiamine on the hepatic insulin signaling pathway in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which are a type 2 diabetes mellitus model. OLETF rats treated with benfotiamine showed decreased body weight gain and reduced adipose tissue weight. In addition, blood glucose levels were lower in OLETF rats treated with benfotiamine. Following treatment with benfotiamine, the levels of Akt phosphorylation (S473/T308) in the OLETF groups increased significantly compared to the OLETF control group so that they were almost identical to the levels observed in the control group. Moreover, benfotiamine restored the phosphorylation levels of both glycogen synthase kinase (GSK)-3alpha/beta (S21, S9) and glycogen synthase (GS; S641) in OLETF rats to nearly the same levels observed in the control group. Overall, these results suggest that benfotiamine can potentially attenuate type 2 diabetes mellitus in OLETF rats by restoring insulin sensitivity through upregulation of Akt phosphorylation and activation of two downstream signaling molecules, GSK-3alpha/beta and GS, thereby reducing blood glucose levels through glycogen synthesis.

Glycogen Synthase Kinase 3 Inactivation Induces Cell Senescence through Sterol Regulatory Element Binding Protein 1-Mediated Lipogenesis in Chang Cells

BACKGROUND: Enhanced lipogenesis plays a critical role in cell senescence via induction of expression of the mature form of sterol regulatory element binding protein 1 (SREBP1), which contributes to an increase in organellar mass, one of the indicators of senescence. We investigated the molecular mechanisms by which signaling molecules control SREBP1-mediated lipogenesis and senescence. METHODS: We developed cellular models for stress-induced senescence, by exposing Chang cells, which are immortalized human liver cells, to subcytotoxic concentrations (200 microM) of deferoxamine (DFO) and H2O2. RESULTS: In this model of stress-induced cell senescence using DFO and H2O2, the phosphorylation profile of glycogen synthase kinase 3alpha (GSK3alpha) and beta corresponded closely to the expression profile of the mature form of SREBP-1 protein. Inhibition of GSK3 with a subcytotoxic concentration of the selective GSK3 inhibitor SB415286 significantly increased mature SREBP1 expression, as well as lipogenesis and organellar mass. In addition, GSK3 inhibition was sufficient to induce senescence in Chang cells. Suppression of GSK3 expression with siRNAs specific to GSK3alpha and beta also increased mature SREBP1 expression and induced senescence. Finally, blocking lipogenesis with fatty acid synthase inhibitors (cerulenin and C75) and siRNA-mediated silencing of SREBP1 and ATP citrate lyase (ACL) significantly attenuated GSK3 inhibition-induced senescence. CONCLUSION: GSK3 inactivation is an important upstream event that induces SREBP1-mediated lipogenesis and consequent cell senescence.

Glycogen Synthase Kinase 3 Inactivation Induces Cell Senescence through Sterol Regulatory Element Binding Protein 1-Mediated Lipogenesis in Chang Cells

BACKGROUND: Enhanced lipogenesis plays a critical role in cell senescence via induction of expression of the mature form of sterol regulatory element binding protein 1 (SREBP1), which contributes to an increase in organellar mass, one of the indicators of senescence. We investigated the molecular mechanisms by which signaling molecules control SREBP1-mediated lipogenesis and senescence. METHODS: We developed cellular models for stress-induced senescence, by exposing Chang cells, which are immortalized human liver cells, to subcytotoxic concentrations (200 microM) of deferoxamine (DFO) and H2O2. RESULTS: In this model of stress-induced cell senescence using DFO and H2O2, the phosphorylation profile of glycogen synthase kinase 3alpha (GSK3alpha) and beta corresponded closely to the expression profile of the mature form of SREBP-1 protein. Inhibition of GSK3 with a subcytotoxic concentration of the selective GSK3 inhibitor SB415286 significantly increased mature SREBP1 expression, as well as lipogenesis and organellar mass. In addition, GSK3 inhibition was sufficient to induce senescence in Chang cells. Suppression of GSK3 expression with siRNAs specific to GSK3alpha and beta also increased mature SREBP1 expression and induced senescence. Finally, blocking lipogenesis with fatty acid synthase inhibitors (cerulenin and C75) and siRNA-mediated silencing of SREBP1 and ATP citrate lyase (ACL) significantly attenuated GSK3 inhibition-induced senescence. CONCLUSION: GSK3 inactivation is an important upstream event that induces SREBP1-mediated lipogenesis and consequent cell senescence.

The Effect of Helicobacter pylori on Epidermal Growth Factor Receptor-Induced Signal Transduction and the Preventive Effect of Celecoxib in Gastric Cancer Cells

BACKGROUND/AIMS: Helicobacter pylori infection induces cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) overexpression, and these factors may engage in cross-talk. The aim of the present study was to evaluate the effect of H. pylori on EGFR signaling pathways and to determine whether celecoxib has an inhibitory effect on this pathway. METHODS: The AGS cell line was cocultured with H. pylori G27 and the isogenic cagE- mutant. The expression of COX-2, EGFR, heparin binding-epidermal growth factor (HB-EGF), and transforming growth factor-beta (TGF-beta) was measured by real time-polymerase chain reaction (RT-PCR). Next, Western blot analyses of COX-2, EGFR, total Akt, phosphorylated Akt (pAkt), and phosphorylated glycogen synthase kinase-3beta (pGSK3beta) were performed after incubating H. pylori-treated AGS cells for 24 hours with various concentrations of celecoxib (0, 10, 20, and 30 micromol/L). RESULTS: H. pylori infection upregulated the mRNA levels of COX-2, EGFR, HB-EGF, and TGF-beta, as detected by RT-PCR. However, AGS cells treated with cagE- mutants, which have a defective type IV secretion system, did not exhibit EGFR upregulation. Celecoxib had inhibitory effects on the H. pylori-induced overexpression of COX-2 (p=0.015), EGFR (p=0.025), pAkt (p=0.025), and pGSK3beta (p=0.029) by Western blot analysis. CONCLUSIONS: H. pylori with an intact type IV secretion system activated the COX-2 and EGFR-Akt pathways in the AGS cell line. As celecoxib exhibited inhibitory effects on the EGFR signaling pathway, the cross-talk of COX-2 and EGFR likely mediates H. pylori-induced gastric cancer.

Ferulic acid regulates the AKT/GSK-3beta/CRMP-2 signaling pathway in a middle cerebral artery occlusion animal model / 한국실험동물학회지

Ferulic acid, a component of the plants Angelica sinensis (Oliv.) Diels and Ligusticum chuanxiong Hort, exerts a neuroprotective effect by regulating various signaling pathways. This study showed that ferulic acid treatment prevents the injury-induced increase of collapsin response mediator protein 2 (CRMP-2) in focal cerebral ischemia. Glycogen synthase kinase-3beta (GSK-3beta) regulates CRMP-2 function through phosphorylation of CRMP-2. Moreover, the pro-apoptotic activity of GSK-3beta is inactivated by phosphorylation by Akt. This study investigated whether ferulic acid modulates the expression of CRMP-2 and its upstream targets, Akt and GSK-3beta, in focal cerebral ischemia. Male rats were treated immediately with ferulic acid (100 mg/kg, i.v.) or vehicle after middle cerebral artery occlusion (MCAO), and then cerebral cortices were collected 24 hr after MCAO. MCAO resulted in decreased levels of phospho-Akt and phospho-GSK-3beta, while ferulic acid treatment prevented the decrease in the levels of these proteins. Moreover, phospho-CRMP-2 and CRMP-2 levels increased during MCAO, whereas ferulic acid attenuated these injury-induced increases. These results demonstrate that ferulic acid regulates the Akt/GSK-3beta/CRMP-2 signaling pathway in focal cerebral ischemic injury, thereby protecting against brain injury.