The effect of Li+ on GSK-3 inhibition: molecular dynamics simulation.
ABSTRACT Glycogen synthase kinase-3 (GSK-3) is a kind of serine-threonine protein kinase. It places important roles in several signaling pathways and it is a key therapeutic target for a number of diseases, such as diabetes, cancer, Alzheimer's disease and chronic inflammation. Mg(2+) ions which interact with ATP are conserved in GSK. They are important in phosphoryl transfer. Li(+) is an inhibitor for GSK-3. It is used to treat bipolar mood disorder. This paper illustrates the effect of Li(+) on GSK-3. When Mg(I)(2+) is replaced by Li(+), the atom fluctuation of GSK-3 will rise, and the in-line phosphoryl transfer mechanism is probably demolished and the binding of pre-phosphorylated substrates may be disturbed. All the results we obtained clearly suggest that inhibition to GSK-3 is caused by the Mg(I)(2+) replacement with Li(+).
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ABSTRACT: Glycogen synthase kinase 3β (GSK3β) is a ubiquitous serine/threonine kinase that plays a pivotal role in many biological processes. GSK3β catalyzes the transfer of γ-phosphate of ATP to the unique substrate Ser/Thr residues with the assistance of two natural activating cofactors Mg(2+) . Interestingly, the biological observation reveals that a non-native Ca(2+) ion can inhibit the GSK3β catalytic activity. Here, the inhibitory mechanism of GSK3β by the displacement of native Mg(2+) at site 1 by Ca(2+) was investigated by means of 80 ns comparative molecular dynamics (MD) simulations of the GSK3β···Mg(2+) -2/ATP/ Mg(2+) -1 and GSK3β···Mg(2+) -2/ATP/Ca(2+) -1 systems. MD simulation results revealed that using the AMBER point charge model force field for Mg(2+) was more appropriate in the reproduction of the active site architectural characteristics of GSK3β than using the magnesium-cationic dummy atom model force field. Compared with the native Mg(2+) bound system, the misalignment of the critical triphosphate moiety of ATP, the erroneous coordination environments around the Mg(2+) ion at site 2, and the rupture of the key hydrogen bond between the invariant Lys85 and the ATP O(β2) atom in the Ca(2+) substituted system were observed in the MD simulation due to the Ca(2+) ion in active site in order to achieve its preferred sevenfold coordination geometry, which adequately abolish the enzymatic activity. The obtained results are valuable in understanding the possible mechanism by why Ca(2+) inhibits the GSK3β activity and also provide insights into the mechanism of Ca(2+) inhibition in other structurally related protein kinases. Proteins 2012. © 2012 Wiley Periodicals, Inc.Proteins Structure Function and Bioinformatics 11/2012; · 3.34 Impact Factor
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ABSTRACT: Wogonin, a flavone from the root of Scutellaria baicalensis Georgi, has shown various biological activities. In our previous study, it was confirmed that wogonin could decrease the expression of hypoxia-inducible factor-1α (HIF-1α) by affecting its stability under hypoxia. However, it is still unknown whether wogonin could influence Wnt/β-catenin pathway under hypoxia. In this study, we found that wogonin disrupted Wnt/β-catenin signaling and reduced the secretion of vascular endothelial growth factor (VEGF, also known as vascular permeability factor, VPF), which increased vascular permeability in certain diseases. It was found that wogonin suppressed HUVECs hyperactivity and actin remodeling induced by hypoxia, inhibited transendothelial cell migration of the human breast carcinoma cell MDA-MB-231 and the extravasated Evans in vivo Miles vascular permeability assay. Wogonin-treated cells showed a decrease in the expression of Wnt protein and its co-receptors, as well as a parallel increase in the expression of Axin and GSK-3β in degradation complex, leading to degradation of β-catenin. In addition, wogonin promoted the binding between Axin and β-catenin, increased ubiquitination of β-catenin and promoted its degradation. Interestingly, wogonin decreased the expression of TCF-1, TCF-3, and LEF-1 and inhibited nuclear accumulation of β-catenin as well as the binding of β-catenin and TCF-1, TCF-3, or LEF-1. All of the above results showed that wogonin could inhibit the expression of VEGF, which is an important factor regulated by β-catenin. Taken together, the results suggested that wogonin was a potent inhibitor of Wnt/β-catenin and influenced vascular permeability, and this might provide new therapeutics in certain diseases. © 2013 Wiley Periodicals, Inc.Molecular Carcinogenesis 10/2013; · 4.27 Impact Factor
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ABSTRACT: Wogonin, a naturally occurring mono-flavonoid, has been reported to have tumor therapeutic potential and good selectivity both in vitro and in vivo. Herein, we investigated the anti-proliferation effects and associated mechanisms of wogonin in human colorectal cancer in vitro. The flow-cytometric analysis showed that wogonin induced a G1 phase cell cycle arrest in HCT116 cells in a concentration- and time-dependent manner. Meanwhile, the cell cycle-related proteins, such as Cyclin A, E, D1, and CDK2, 4 were down-regulated in wogonin-induced G1 cell cycle arrest. Furthermore, we showed that the anti-proliferation and G1 arrest effect of wogonin on HCT116 cells was associated with deregulation of Wnt/β-catenin signaling pathway. Wogonin-treated cells showed decreased intracellular levels of Wnt proteins, and activated degradation complex to phosphorylated and targeted β-catenin for proteasomal degradation. Wogonin inhibited β-catenin-mediated transcription by interfering in the transcriptional activity of TCF/Lef, and repressing the kinase activity of CDK8 which has been considered as an oncogene involving in the development of colorectal cancers. Moreover, CDK8 siRNA-transfected HCT116 cells showed similar results to wogonin treated cells. Thus, our data suggested that wogonin induced anti-proliferation and G1 arrest via Wnt/β-catenin signaling pathway and it can be developed as a therapeutic agent against human colorectal cancer.Toxicology 07/2013; · 3.75 Impact Factor