ABSTRACT
We aimed to study the role of protein L-isoaspartyl methyltransferase (PIMT) in neuronal differentiation using basic fibroblast growth factor (bFGF)-induced neuronal differentiation, characterized by cell-body shrinkage, long neurite outgrowth, and expression of neuronal differentiation markers light and medium neurofilaments (NF). The bFGF-mediated neuronal differentiation of PC12 cells was induced through activation of mitogen-activated protein kinase (MAPK) signaling molecules [MAPK kinase 1/2 (MEK1/2), extracellular signal-regulated kinase 1/2 (ERK1/2), and p90RSK], and phosphatidylinositide 3-kinase (PI3K)/Akt signaling molecules PI3Kp110ß, PI3Kp110γ, Akt, and mTOR. Inhibitors (adenosine dialdehyde and S-adenosylhomocysteine) of protein methylation suppressed bFGF-mediated neuronal differentiation of PC12 cells. PIMTeficiency caused by PIMT-specific siRNA inhibited neuronal differentiation of PC12 cells by suppressing phosphorylation of MEK1/2 and ERK1/2 in the MAPK signaling pathway and Akt and mTOR in the PI3K/Akt signaling pathway. Therefore, these results suggested that PIMT was critical for bFGF-mediated neuronal differentiation of PC12 cells and regulated the MAPK and Akt signaling pathways. [BMB Reports 2016; 49(8): 437-442].
Subject(s)
Cell Differentiation/drug effects , Fibroblast Growth Factor 2/pharmacology , Neurons/cytology , Neurons/enzymology , Protein D-Aspartate-L-Isoaspartate Methyltransferase/metabolism , Animals , Mitogen-Activated Protein Kinases/metabolism , Neurons/drug effects , PC12 Cells , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Rats , Signal Transduction/drug effectsABSTRACT
Gouania leptostachya DC. var. tonkinensis Pitard. Rhamnaceae is a traditional medicinal plant used in Thailand for treating various inflammatory symptoms. However, no systematic studies have been performed concerning the anti-inflammatory effects or molecular mechanisms of this plant. The immunopharmacological activities of a methanol extract from the leaves and twigs of G. leptostachya (Gl-ME) were elucidated based on the gastritis symptoms of mice treated with HCl/EtOH and the inflammatory responses, such as nitric oxide (NO) release and prostaglandin E2 (PGE2) production, from RAW264.7 cells and peritoneal macrophages. Moreover, inhibitory target molecules were also assessed. Gl-ME dose-dependently diminished the secretion of NO and PGE2 from LPS-stimulated RAW264.7 cells and peritoneal macrophages. The gastritis lesions of HCl/EtOH-treated mice were also attenuated after Gl-ME treatment. The extract (50 and 300 µg/mL) clearly reduced mRNA expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2, nuclear translocation of p65/nuclear factor (NF)-κB, phosphorylation of p65-activating upstream enzymes, such as protein kinase B (AKT), inhibitor of κBα kinase (IKK), and inhibitor of κB (IκBα), and the enzymatic activity of Src. By HPLC analysis, one of the major components in the extract was revealed as resveratrol with NO and Src inhibitory activities. Moreover, this compound suppressed NO production and HCl/EtOH-induced gastric symptoms. Therefore, these results suggest that Gl-ME might be useful as an herbal anti-inflammatory medicine through the inhibition of Src and NF-κB activation pathways. The efficacy data of G. leptostachya also implies that this plant could be further tested to see whether it can be developed as potential anti-inflammatory preparation.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Macrophages, Peritoneal/drug effects , Plant Extracts/pharmacology , Rhamnaceae/chemistry , Stilbenes/pharmacology , Animals , Cell Line , Cyclooxygenase 2/metabolism , Dinoprostone/metabolism , Gastritis/drug therapy , I-kappa B Proteins/metabolism , Lipopolysaccharides/pharmacology , Male , Mice , Mice, Inbred C57BL , Mice, Inbred ICR , NF-KappaB Inhibitor alpha , NF-kappa B/metabolism , Nitric Oxide/metabolism , Nitric Oxide Synthase Type II/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Resveratrol , ThailandABSTRACT
Numerous derivatives of kojic acid have been synthesised to expand its immunopharmacological uses. Kojic acid is known to have anti-cancer, anti-inflammatory, and anti-melanogenesis effects. We found that (5-hydroxy-4-oxo-4H-pyran-2-yl)methyl 6-hydroxynaphthalene-2-carboxylate (MHNC) strongly suppressed the production of nitric oxide (NO) in an initial screening experiment. In this study, we explored the in vitro and in vivo anti-inflammatory activity of MHNC and its inhibitory mechanisms using lipopolysaccharide (LPS)-treated RAW264.7 cells and HCl/EtOH-treated ICR mice. MHNC dose-dependently diminished the secretion of nitric oxide (NO) and prostaglandin (PG)E2 in LPS-treated RAW264.7 cells. This compound also suppressed the upregulation of mRNA levels for the inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 genes. Additionally, the transcriptional activation of these genes was inhibited by MHNC through the suppression of the nuclear translocation of nuclear factor (NF)-κB subunits (p65 and p50), as determined by a luciferase reporter assay. Interestingly, MHNC treatment was found to suppress a series of upstream signalling cascades consisting of IκBα, AKT, PDK1, Src, and Syk for NF-κB activation. Furthermore, a direct enzyme assay with purified Src and Syk and luciferase assays using Src and Syk overexpression indicated that these enzymes were directly inhibited by MHNC. Finally, MHNC (20mg/kg) prevented inflammatory symptoms of the stomach in mice treated with HCl/EtOH by reducing phospho-IκBα levels. Taken together, our data suggest that MHNC may negatively modulate in vitro and in vivo inflammatory responses via the direct suppression of Syk/Src and NF-κB.
