ABSTRACT
Type 2 diabetes manifests beta cell deficiencies and alpha cell expansion which is consistent with relative insulin deficiency and glucagon oversecretion. The effects of hyperglycemia on alpha cells are not as understood in comparison to beta cells. Hyperglycemia increases oxidative stress, which induces Akt activation or FoxO activation, depending on cell type. Several studies independently reported that FoxO1 translocations in alpha cells and beta cells were opposite. We compared the responses of pancreatic alpha cells and beta cells against hyperglycemia. Alpha TC-1 cells and Beta TC-6 cells were incubated with control (5mM Glucose) or high glucose (33mM Glucose) with or without PI3K inhibitor or FoxO1 inhibitor. We assessed PI3K, pAkt and phosphorylated FoxO1 (pFoxO1) in both cell lines. Immunostaining of BrdU and FoxO1 was detected by green fluorescence microscopy and confocal microscopy. Hyperglycemia and H2O2 decreased PI3K and pAKT in beta cells, but increased them in alpha cells. FoxO1 localizations and pFoxO1 expressions between alpha cells and beta cells were opposite. Proliferation of beta cells was decreased, but alpha cell proliferation was increased under hyperglycemia. Antioxidant enzymes including superoxide dismutase (SOD) and catalase were increased in beta cells and they were reversed with FoxO1 inhibitor treatment. Increased proliferation in alpha cells under hyperglycemia was attenuated with PI3K inhibitor. In conclusion, hyperglycemia increased alpha cell proliferation and glucagon contents which are opposite to beta cells. These differences may be related to contrasting PI3K/pAkt changes in both cells and subsequent FoxO1 modulation.
Subject(s)
Diabetes Mellitus, Type 2/metabolism , Forkhead Box Protein O1/analysis , Glucagon-Secreting Cells/metabolism , Hyperglycemia/metabolism , Insulin-Secreting Cells/metabolism , Proto-Oncogene Proteins c-akt/analysis , Adenoma , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Forkhead Box Protein O1/antagonists & inhibitors , Glucagon/analysis , Glucagon-Secreting Cells/chemistry , Glucose/administration & dosage , Glucose/metabolism , Hydrogen Peroxide/pharmacology , Insulin/metabolism , Insulin Secretion , Insulin-Secreting Cells/chemistry , Insulinoma , Mice , Pancreatic Neoplasms , Phosphatidylinositol 3-Kinases/analysis , Phosphoinositide-3 Kinase Inhibitors , PhosphorylationABSTRACT
It has been suggested that taurine chloramine (TauCl) plays an important role in the downregulation of proinflammatory mediators. However, little is known about its effect on the expression of matrix metalloproteinases (MMPs). In this study, we investigated the effects of TauCl on synovial expression of MMPs. The effects of TauCl on MMP expression in IL-1beta stimulated fibroblast-like synoviocytes (FLSs) were studied using the following techniques. Real-time PCR and semi-quantitative PCR were employed to analyze the mRNA expression of MMPs. ELISA was used to determine protein levels of MMPs. Western blot analyses were performed to analyze the mitogen-activated protein kinase and inhibitor of nuclear factor-kappaB (IkappaB) kinase signalling pathways. Finally, electrophoretic mobility shift assay and immunohistochemistry were used to assess localization of transcription factors. IL-1beta increased the transcriptional and translational levels of MMP-1 and MMP-13 in rheumatoid arthritis FLSs, whereas the levels of MMP-2 and MMP-9 were unaffected. TauCl at a concentration of 400 to 600 micromol/l greatly inhibited the transcriptional and translational expression of MMP-13, but the expression of MMP-1 was significantly inhibited at 800 micromol/l. At a concentration of 600 micromol/l, TauCl did not significantly inhibit phosphorylation of mitogen-activated protein kinase or IkappaB degradation in IL-1beta stimulated rheumatoid arthritis FLSs. The degradation of IkappaB was significantly inhibited at a TauCl concentration of 800 micromol/l. The inhibitory effect of TauCl on IkappaB degradation was confirmed by electrophoretic mobility shift assay and immunochemical staining for localization of nuclear factor-kappaB. TauCl differentially inhibits the expression of MMP-1 and MMP-13, and inhibits expression of MMP-1 primarily through the inhibition of IkappaB degradation, whereas it inhibits expression of MMP-13 through signalling pathways other than the IkappaB pathway.
Subject(s)
Enzyme Inhibitors/pharmacology , Fibroblasts/drug effects , Interleukin-1beta/pharmacology , Matrix Metalloproteinase Inhibitors , Taurine/analogs & derivatives , Arthritis, Rheumatoid , Cells, Cultured , Dose-Response Relationship, Drug , Fibroblasts/enzymology , Fibroblasts/pathology , Gene Expression/drug effects , Humans , Matrix Metalloproteinase 1/biosynthesis , Matrix Metalloproteinase 1/genetics , Matrix Metalloproteinase 13/biosynthesis , Matrix Metalloproteinase 13/genetics , Signal Transduction , Synovial Membrane/cytology , Taurine/pharmacologyABSTRACT
In an attempt to develop an antiinflammatory herbal remedy that is as potent as current synthetic medicines, the cortex of Phellodendron amurense Rupr (Rutaceae) and the rhizomes of Coptis chinensis Franch (Ranunculaceae) were combined in a 2:1 ratio. This ratio was chosen based on in vitro experiments and traditional Asian medicine prescriptions. The combined ethanol extract, named RAH13, was evaluated for antiinflammatory properties using animal models of acute inflammation such as the croton oil-induced ear edema test and an acetic acid-induced capillary permeability test. Models of chronic inflammation were also tested using the cotton pellet test and a delayed-type hypersensitivity (DTH) test. Oral administration of RAH13 at a dose of 200 mg/kg showed in vivo antiinflammatory activity as potent as the effects associated with 100 mg/mL of celecoxib or 1 mg/kg of dexamethasone. These effects were seen in both acute and chronic inflammation models, suggesting that RAH13 may be effective in controlling some inflammation-related diseases.