Glycogen Synthase Kinase-3 - An Overview of An Over-Achieving Protein Kinase
ABSTRACT Glycogen synthase kinase-3 (GSK-3) has attracted much scrutiny due to its plethora of cellular functions, novel mechanisms of regulation and its potential as a therapeutic target for several common diseases. In mammals, GSK-3 is encoded by two genes, termed GSK-3alpha and GSK-3beta, that yield related but distinct protein-serine kinases. GSK-3 is unusual in that its protein kinase activity tends to be high in resting cells and cellular stimuli, such as hormones and growth factors, result in its catalytic inactivation. Further, many of the substrate proteins of GSK-3 are functionally inhibited by phosphorylation. Thus, signals that inhibit GSK-3 often cause activation of its diverse array of target proteins. Regulation of GSK-3 is important for normal development, regulation of metabolism, neuronal growth and differentiation and modulation of cell death. Dysregulation of GSK-3 activity has been implicated in human pathologies such as neurodegenerative diseases and type-2 diabetes. In this introductory chapter we provide a primer on the modes of GSK-3 regulation and a description of the various signaling pathways and cellular processes in which GSK-3 is an active participant.
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- "A number of human diseases are connected to dysfunctions of GSK-3 (e.g. Alzheimer's disease, type 2 diabetes and cancer)        . The diversity of GSK-3 functions led to speculations about possible physiological roles of PfGSK-3, including metabolism regulation, cell cycle control and differentiation processes  . "
ABSTRACT: Plasmodium falciparum glycogen synthase kinase-3 (PfGSK-3) is one of the eukaryotic protein kinases that were identified as essential for the parasite causing malaria tropica. Although the physiological functions of PfGSK-3 are still unknown, it had been suggested as a putative target for novel antimalarial drugs. The high structural similarity of PfGSK-3 and its human orthologue HsGSK-3 makes the development of selective PfGSK-3 inhibitors a challenging task. Actually, established GSK-3 inhibitors are either unselective or are more potent for inhibition of the mammalian GSK-3. A high throughput screening campaign identified thieno[2,3-b]pyridines as a new class of PfGSK-3 inhibitors. Systematic variation of the substitution pattern at the parent scaffold led to compounds which selectively inhibited the plasmodial enzyme. These compounds also exhibited activity against erythrocyte stages of the parasites. A hypothetical explanation for the selectivity of the new antimalarial compounds was enunciated based on the results of docking a selective inhibitor into a PfGSK-3 homology model and by comparison of the results with an x-ray structure of HsGSK-3 co-crystallized with a similar but unselective compound. Copyright © 2015. Published by Elsevier B.V.Biochimica et Biophysica Acta 04/2015; DOI:10.1016/j.bbapap.2015.03.013 · 4.66 Impact Factor
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- "GSK3β is a highly activated serine/threonine kinase in resting cells with normal metabolism . Besides its influence on the glycogen synthesis GSK3β is involved in Wnt/β-catenin and Phosphatidylinositole 3 kinase (PI3K)/Akt signaling antagonizing cell growth and cell cycle progression in both pathways. "
ABSTRACT: Prognosis of adult patients suffering from acute lymphoblastic leukemia (ALL) is still unsatisfactory. Targeted therapy via inhibition of deregulated signaling pathways appears to be a promising therapeutic option for the treatment of ALL. Herein, we evaluated the influence of a novel arylindolylmaleimide (PDA-66), a potential GSK3beta inhibitor, on several ALL cell lines. ALL cell lines (SEM, RS4;11, Jurkat and MOLT4) were exposed to different concentrations of PDA-66. Subsequently, proliferation, metabolic activity, apoptosis and necrosis, cell cycle distribution and protein expression of Wnt and PI3K/Akt signaling pathways were analyzed at different time points. PDA-66 inhibited the proliferation of ALL cells significantly by reduction of metabolic activity. The 72 h IC50 values ranged between 0.41 to 1.28 muM PDA-66. Additionally, caspase activated induction of apoptosis could be detected in the analyzed cell lines. PDA-66 influenced the cell cycle distribution of ALL cell lines differently. While RS4;11 and MOLT4 cells were found to be arrested in G2 phase, SEM cells showed an increased cell cycle in G0/1 phase. PDA-66 displays significant antileukemic activity in ALL cells and classifies as candidate for further evaluation as a potential drug in targeted therapy of ALL.BMC Cancer 02/2014; 14(1):71. DOI:10.1186/1471-2407-14-71 · 3.36 Impact Factor
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- "Furthermore, Akt is also involved in the regulation of glycogen synthesis through the actions of the serine/threonine kinase glycogen synthase kinase 3 (GSK3) which consists of two isoforms, GSK3α and GSK3β and which phosphorylates and inactivates glycogen synthase (GS) [35,38,39]. In resting cells, GSK3 activity is high but on stimulation, GSK3 is inactivated through phosphorylation; GSK3α is phosphorylated at Ser 21 and GSK3β at the equivalent residue, Ser 9 [38,39]. "
ABSTRACT: Exposure to maternal obesity before and/or throughout pregnancy may increase the risk of obesity and insulin resistance in the offspring in childhood and adult life, therefore, resulting in its transmission into subsequent generations. We have previously shown that exposure to maternal obesity around the time of conception alone resulted in increased adiposity in female lambs. Changes in the abundance of insulin signalling molecules in skeletal muscle and adipose tissue precede the development of insulin resistance and type 2 diabetes. It is not clear, however, whether exposure to maternal obesity results in insulin resistance in her offspring as a consequence of the impact of increased adiposity on skeletal muscle or as a consequence of the programming of specific changes in the abundance of insulin signalling molecules in this tissue. We have used an embryo transfer model in the sheep to investigate the effects of exposure to either maternal obesity or to weight loss in normal and obese mothers preceding and for one week after conception on the expression and abundance of insulin signalling molecules in muscle in the offspring. We found that exposure to maternal obesity resulted in lower muscle GLUT-4 and Ser 9 phospho-GSK3α and higher muscle GSK3α abundance in lambs when compared to lambs conceived in normally nourished ewes. Exposure to maternal weight loss in normal or obese mothers, however, resulted in lower muscle IRS1, PI3K, p110β, aPKCζ, Thr 642 phospho-AS160 and GLUT-4 abundance in the offspring. In conclusion, maternal obesity or weight loss around conception have each programmed specific changes on subsets of molecules in the insulin signalling, glucose transport and glycogen synthesis pathways in offspring. There is a need for a stronger evidence base to ensure that weight loss regimes in obese women seeking to become pregnant minimize the metabolic costs for the next generation.PLoS ONE 12/2013; 8(12):e84594. DOI:10.1371/journal.pone.0084594 · 3.23 Impact Factor