Glycogen Synthase Kinase-3 Gene Research Articles

Function of glycogen synthase kinase3 in embryogenesis of Dermanyssus gallinae

In the life cycle of Dermanyssus gallinae, the embryo is a developmental stage that does not require blood meals, but needs glucose to produce adenosine triphosphate (ATP) through glycolysis or oxidative phosphorylation, providing energy for embryonic development. Glycogen synthase kinase 3 (GSK3), belonging to the serine/threonine kinase family, is a key enzyme involved in glycogen metabolism in many eukaryotes, but not be described in D. gallinae. The present study was conducted to explore the role of Dg-GSK3 in the embryogenesis of D. gallinae. The results of qPCR showed that Dg-GSK3 mRNA was expressed in different development stages of D. gallinae embryos. RNA interference (RNAi) was performed on the female mites and eggs by immersion, and it was found that lowering GSK3 expression level could significantly decrease the female egg laying rate and egg hatching rate (P < 0.05). Some eggs became shrunken and shriveled in appearance. The fecundity of female D. gallinae obtained from the rDg-GSK3-immunized group of chickens (2.56 ± 0.35 eggs per mite, P < 0.0001) decreased significantly from that of the control group (3.49 ± 0.35). The oviposition rate of rDg-GSK3-immunized group (75.94 ± 7.28 %, P = 0.0003）was significantly lower that of the control group (89.69 ± 2.63 %). In conclusion, Dg-GSK3 is a crucial gene during the embryogenesis of D. gallinae, which can affect both the female fecundity and the egg hatching, which help us understand the function of GSK3 gene in the embryogenesis of mites.

Silencing of Glycogen Synthase Kinase 3 Significantly Inhibits Chitin and Fatty Acid Metabolism in Asian Citrus Psyllid, Diaphorina citri.

Glycogen is a predominant carbohydrate reserve in various organisms, which provides energy for different life activities. Glycogen synthase kinase 3 (GSK3) is a central player that catalyzes glucose and converts it into glycogen. In this study, a GSK3 gene was identified from the D. citri genome database and named DcGSK3. A reverse transcription quantitative PCR (RT-qPCR) analysis showed that DcGSK3 was expressed at a high level in the head and egg. The silencing of DcGSK3 by RNA interference (RNAi) led to a loss-of-function phenotype. In addition, DcGSK3 knockdown decreased trehalase activity, glycogen, trehalose, glucose and free fatty acid content. Moreover, the expression levels of the genes associated with chitin and fatty acid synthesis were significantly downregulated after the silencing of DcGSK3. According to a comparative transcriptomics analysis, 991 differentially expressed genes (DEGs) were identified in dsDcGSK3 groups compared with dsGFP groups. A KEGG enrichment analysis suggested that these DEGs were primarily involved in carbon and fatty acid metabolism. The clustering analysis of DEGs further confirmed that chitin and fatty acid metabolism-related DEGs were upregulated at 24 h and were downregulated at 48 h. Our results suggest that DcGSK3 plays an important role in regulating the chitin and fatty acid metabolism of D. citri.

Glycogen Synthase Kinase 3 Gene Is Important in Growth and Molting of the Pacific White Shrimp Litopenaeus vannamei

Glycogen synthase kinase 3 (GSK3) is a vital multifunctional molecule that is widely distributed in invertebrates and vertebrates. GSK3 is a highly conserved serine/threonine (Ser/Thr) protein kinase, which plays an important role in insulin, Wnt, and various signaling pathways. In this study, a GSK3 gene were identified in the genome of the Pacific white shrimp, Litopenaeus vannamei, and analyzed its gene structure, phylogeny, and expression profiles. The deduced LvGSK3 protein contains a highly conserved Ser/Thr protein kinase catalytic (S_TKc) domain, the LvGSK3 gene exhibited high expression in different early developmental stages, most adult tissues, and premolting stages. RNA interference of LvGSK3 significantly retarded the increment of body weight and affected the expressions of molting-related genes compared with control groups. These results will improve our understanding of the conserved structure and functions of the LvGSK3 gene and show potential applications of shrimp growth.

Glycogen Synthase Kinase 3β Enhances Hepatitis C Virus Replication by Supporting miR-122

Hepatitis C virus (HCV) infection is associated with alterations in host lipid and insulin signaling cascades, which are partially explained by a dependence of the HCV life cycle on key molecules in these metabolic pathways. Yet, little is known on the role in the HCV life cycle of glycogen synthase kinase 3 (GSK3), one of the most important kinases in cellular metabolism. Therefore, the impact of GSK3 on the HCV life cycle was assessed in human hepatoma cell lines harboring subgenomic genotype 1b and 2a replicons or producing cell culture-derived HCV genotype 2a by exposure to synthetic GSK3 inhibitors, GSK3 gene silencing, overexpression of GSK3 constructs and immunofluorescence analyses. In addition, the role of GSK3 in hepatitis E virus (HEV) replication was investigated to assess virus specificity of the observed findings. We found that both inhibition of GSK3 function by synthetic inhibitors as well as silencing of GSK3β gene expression resulted in a decrease of HCV replication and infectious particle production, whereas silencing of the GSK3α isoform had no relevant effect on the HCV life cycle. Conversely, overexpression of GSK3β resulted in enhanced HCV replication. In contrast, GSK3β had no effect on replication of subgenomic HEV replicon. The pro-viral effect of GSK3β on HCV replication was mediated by supporting expression of microRNA-122 (miR-122), a micro-RNA which is mandatory for wild-type HCV replication, as GSK3 inhibitors suppressed miR-122 levels and as inhibitors of GSK3 had no antiviral effect on a miR-122-independent HCV mutant. In conclusion, we have identified GSK3β is a novel host factor supporting HCV replication by maintaining high levels of hepatic miR-122 expression.

Glycogen Synthase Kinase-3 is involved in glycogen metabolism control and embryogenesis of Rhodnius prolixus.

Rhodnius prolixus is a blood-feeding insect that transmits Trypanosoma cruzi and Trypanosoma rangeli to vertebrate hosts. Rhodnius prolixus is also a classical model in insect physiology, and the recent availability of R. prolixus genome has opened new avenues on triatomine research. Glycogen synthase kinase 3 (GSK-3) is classically described as a key enzyme involved in glycogen metabolism, also acting as a downstream component of the Wnt pathway during embryogenesis. GSK-3 has been shown to be highly conserved among several organisms, mainly in the catalytic domain region. Meanwhile, the role of GSK-3 during R. prolixus embryogenesis or glycogen metabolism has not been investigated. Here we show that chemical inhibition of GSK-3 by alsterpaullone, an ATP-competitive inhibitor of GSK3, does not affect adult survival rate, though it alters oviposition and egg hatching. Specific GSK-3 gene silencing by dsRNA injection in adult females showed a similar phenotype. Furthermore, bright field and 4'-6-diamidino-2-phenylindole (DAPI) staining analysis revealed that ovaries and eggs from dsGSK-3 injected females exhibited specific morphological defects. We also demonstrate that glycogen content was inversely related to activity and transcription levels of GSK-3 during embryogenesis. Lastly, after GSK-3 knockdown, we observed changes in the expression of the Wingless (Wnt) downstream target β-catenin as well as in members of other pathways such as the receptor Notch. Taken together, our results show that GSK-3 regulation is essential for R. prolixus oogenesis and embryogenesis.

Effect of Imipramine, Paroxetine, and Lithium Carbonate on Neurobehavioral Changes of Streptozotocin in Rats: Impact on Glycogen Synthase Kinase-3 and Blood Glucose Level

Recent studies have demonstrated a scrutinized association of diabetes mellitus with depressive symptoms and major depression. Glycogen synthase kinase-3 (GSK-3) is a protein kinase enzyme constitutively active in non-stimulated cells and in multiple signalings. Independent lines of research provide a converging evidence for an involvement of GSK-3 in the regulation of behavior and hyperglycemia. The present study revealed that streptozotocin (STZ)-induced diabetic rats were found to show lengthened duration of immobility in the forced-swimming test (FST) and reduced locomotor and exploratory activities in the open-field test (OFT). Imipramine (15mg/kg), Paroxetine (10mg/kg) and lithium carbonate (36.94mg/kg) for 14days reduced immobility behavior in FST. Paroxetine and lithium carbonate increased the locomotor and exploratory activities, while imipramine decreased the locomotor activity in the OFT. Imipramine and lithium carbonate reduced the blood glucose level while paroxetine didn't alter it. STZ-induced diabetes increased GSK-3 gene expression which was determined using the reverse transcription-quantitative polymerase chain reaction test, while the three drugs decreased its expression. It can be concluded that lithium carbonate and imipramine can control both hyperglycemia and the associated symptoms of depression at the same time by inhibiting GSK-3 activity. On the other hand, paroxetine may only manage the depressive-like symptoms associated with diabetes through modulating the enzyme GSK-3, without changing blood glucose levels.

GSK-3β Inhibition Affects Singing Behavior and Neurogenesis in Adult Songbirds

GSK-3 (glycogen synthase kinase-3) is a serine/threonine kinase which is a critical regulator in neuronal signaling, cognition, and behavior. We have previously shown that unlike other vertebrates that harbor both α and β GSK-3 genes, the α gene is missing in birds. Therefore, birds can be used as a new animal model to study the roles of GSK-3β in behavior and in regulating adult neurogenesis. In the present study, we inhibited GSK-3β in brains of adult male zebra finches (Taeniopygia guttata) and accordingly investigated how this inhibition affects behavior and cell proliferation. Our results show that GSK-3 inhibition: (1) affects specific aspects of singing behavior, which might be related to social interactions in birds, and (2) differentially affects cell proliferation in various parts of the ventricular zone. Taken together, our study demonstrates a role of GSK-3β in regulating singing behavior and neuronal proliferation in birds and highlights the importance of GSK-3β in modulating cognitive abilities as well as social behavior.

VPA inhibits myo‐inositol phosphate synthase activity by inhibition of Gsk3 (LB150)

Valproic acid (VPA) has been used for decades for the treatment of bipolar disorder. Yet, the therapeutic mechanism of VPA is not understood, hindering the development of more effective drugs. VPA causes inositol depletion in the human brain cells and in yeast cells. A similar degree of inositol depletion was observed in the yeast gsk3Δ mutant, in which the four glycogen synthase kinase 3 (GSK3) homologs were deleted including MCK1, MRK1, MDS1 and YGK3. VPA was also shown to inhibit Gsk3 in mammalian cells. These findings suggest that Gsk3 may play a role in inositol metabolism, and that VPA may cause inositol depletion by inhibiting Gsk3. The rate limiting enzyme in yeast inositol de novo synthesis is myo‐inositol phosphate synthase (MIPS). VPA treatment has been shown to cause a 50% decrease in MIPS activity. However, VPA did not inhibit MIPS in gsk3Δ cells, suggesting that VPA‐induced inositol depletion occurs by inhibition of Gsk3, leading to decreased MIPS activity. Of the four GSK3 homologs, we show that MCK1 is required for optimal inositol synthesis. mck1Δ is the only GSK3 single mutant that exhibited multiple features of inositol depletion, including inositol‐dependent growth, decreased intracellular inositol and decreased MIPS activity. VPA‐induced inhibition of MIPS was not observed in mck1Δ, indicating that Mck1 is required by VPA to inhibit MIPS. To verify that MCK1 is the sole GSK3 gene involved in regulating inositol metabolism, a triple mutant (mrk1Δmds1Δygk3Δ) was constructed. The triple mutant exhibited normal growth in inositol‐free media and increased intracellular inositol compared to WT, indicating that inositol depletion observed in gsk3Δ does not result from deletion of MRK1, MDS1 or YGK3. In conclusion, MCK1 is the yeast GSK3 homolog required for optimal inositol synthesis and VPA‐induced inhibition of MIPS is Mck1 dependent.Grant Funding Source: Supported by NIH‐DK081367 &amp; Wayne State University Enhancement Award for Doctoral Student Travel

Aberrant spindle dynamics and cytokinesis in Dictyostelium discoideum cells that lack glycogen synthase kinase 3

Eukaryotic cell division requires the co-ordinated assembly and disassembly of the mitotic spindle, accurate chromosome segregation and temporal control of cytokinesis to generate two daughter cells. While the absolute details of these processes differ between organisms, there are evolutionarily conserved core components common to all eukaryotic cells, whose identification will reveal the key processes that control cell division. Glycogen synthase kinase 3 (GSK-3) is a major protein kinase found throughout the eukaryotes and regulates many processes, including cell differentiation, growth, motility and apoptosis. In animals, GSK-3 associates with mitotic spindles and its inhibition causes mis-regulation of chromosome segregation. Two suppressor screens in yeast point to a more general effect of GSK-3 on cell division, however the direct role of GSK-3 in control of mitosis has not been explored outside the animal kingdom. Here we report that the Dictyostelium discoideum GSK-3 orthologue, GskA, associates with the mitotic spindle during cell division, as seen for its mammalian counterparts. Dictyostelium possesses only a single GSK-3 gene that can be deleted to eliminate all GSK-3 activity. We found that gskA-null mutants failed to elongate their mitotic spindle and were unable to divide in shaking culture, but have no chromosome segregation defect. These results suggest further conservation for the role of GSK-3 in the regulation of spindle dynamics during mitosis, but also reveal differences in the mechanisms ensuring accurate chromosome segregation.

Selective loss of glycogen synthase kinase-3α in birds reveals distinct roles for GSK-3 isozymes in tau phosphorylation

Mammalian glycogen synthase kinase-3 (GSK-3), a critical regulator in neuronal signaling, cognition, and behavior, exists as two isozymes GSK-3α and GSK-3β. Their distinct biological functions remains largely unknown. Here, we examined the evolutionary significance of each of these isozymes. Surprisingly, we found that unlike other vertebrates that harbor both GSK-3 genes, the GSK-3α gene is missing in birds. GSK-3-mediated tau phosphorylation was significantly lower in adult bird brains than in mouse brains, a phenomenon that was reproduced in GSK-3α knockout mouse brains. Tau phosphorylation was detected in brains from bird embryos suggesting that GSK-3 isozymes play distinct roles in tau phosphorylation during development. Birds are natural GSK-3α knockout organisms and may serve as a novel model to study the distinct functions of GSK-3 isozymes.

Evidence that glycogen synthase kinase‐3 isoforms have distinct substrate preference in the brain

Mammalian glycogen synthase kinase-3 (GSK3) is generated from two genes, GSK3α and GSK3β, while a splice variant of GSK3β (GSK3β2), containing a 13 amino acid insert, is enriched in neurons. GSK3α and GSK3β deletions generate distinct phenotypes. Here, we show that phosphorylation of CRMP2, CRMP4, β-catenin, c-Myc, c-Jun and some residues on tau associated with Alzheimer's disease, is altered in cortical tissue lacking both isoforms of GSK3. This confirms that they are physiological targets for GSK3. However, deletion of each GSK3 isoform produces distinct substrate phosphorylation, indicating that each has a different spectrum of substrates (e.g. phosphorylation of Thr509, Thr514 and Ser518 of CRMP is not detectable in cortex lacking GSK3β, yet normal in cortex lacking GSK3α). Furthermore, the neuron-enriched GSK3β2 variant phosphorylates phospho-glycogen synthase 2 peptide, CRMP2 (Thr509/514), CRMP4 (Thr509), Inhibitor-2 (Thr72) and tau (Ser396), at a lower rate than GSK3β1. In contrast phosphorylation of c-Myc and c-Jun is equivalent for each GSK3β isoform, providing evidence that differential substrate phosphorylation is achieved through alterations in expression and splicing of the GSK3 gene. Finally, each GSK3β splice variant is phosphorylated to a similar extent at the regulatory sites, Ser9 and Tyr216, and exhibit identical sensitivities to the ATP competitive inhibitor CT99021, suggesting upstream regulation and ATP binding properties of GSK3β1 and GSK3β2 are similar.

Role of Glycogen Synthase Kinase 3 (GSK-3) in innate immune response of human immature dendritic cells toAspergillus fumigatus

Dysregulation of the Th1/Th2 cytokine balance and a switch to a Th2 immune response contribute to the development of and the unfavorable outcome from invasive aspergillosis (IA). We explore in this paper the role of glycogen synthase kinase 3 (GSK-3) in human immature dendritic cells (iDCs) relative to infection caused by A. fumigatus by the use of GSK-3 inhibitors (LiCl, SB415286) and RNA interference technology. In iDCs exposed to A. fumigatus germ tubes, inhibition of GSK-3 with LiCl or SB415286, as well as transfection with small interfering RNA, led to markedly elevated expression of the anti-inflammatory cytokine IL-10. In contrast, pro-inflammatory cytokine response was only partially regulated by GSK-3. Screening of patients after allogeneic stem cell transplantation (with or without IA) for the presence of genetic markers (rs334558, rs6438552) in the GSK-3 gene revealed no significant association with an increased risk for IA. In conclusion, GSK-3 might be involved in the regulation of the anti-inflammatory response of iDCs in the context of infections due to A. fumigatus, albeit the exact mechanisms have to be clarified in future experiments.

Isolation and characterization of a novel glycogen synthase kinase-3 gene, GmGSK, in Glycine max L. that enhances abiotic stress tolerance in Saccharomyces cerevisiae

A novel glycogen synthase kinase-3 gene, GmGSK, was isolated from Glycine max. It is 1,596 bp in length with one ORF of 410 amino acids. Southern blot analysis revealed that it has at least two copies in the G. max genome. GmGSK, when transiently expressed in Nicotiana tabacum leaves, was localized in both cell membrane and cytoplasm. Northern blot analysis indicated that GmGSK is expressed in all tissues, with highest expression in the root. GmGSK can be induced by various abiotic stresses. When transformed with GmGSK, Saccharomyces cerevisiae exhibited enhanced resistance to salt and drought stress.

Planarian GSK3s are involved in neural regeneration

Glycogen synthase kinase-3 (GSK3) is a key element in several signaling cascades that is known to be involved in both patterning and neuronal organization. It is, therefore, a good candidate to play a role in neural regeneration in planarians. We report the characterization of three GSK3 genes in Schmidtea mediterranea. Phylogenetic analysis shows that Smed-GSK3.1 is highly conserved compared to GSK3 sequences from other species, whereas Smed-GSK3.2 and Smed-GSK3.3 are more divergent. Treatment of regenerating planarians with 1-azakenpaullone, a synthetic GSK3 inhibitor, suggests that planarian GSK3s are essential for normal differentiation and morphogenesis of the nervous system. Cephalic ganglia appear smaller and disconnected in 1-azakenpaullone-treated animals, whereas visual axons are ectopically projected, and the pharynx does not regenerate properly. This phenotype is consistent with a role for Smed-GSK3s in neuronal polarization and axonal growth.

Kei on GSK: a contribution by the 2007 recipient of the Young Scientist Award

EDITORIAL FOCUSKei on GSK: a contribution by the 2007 recipient of the Young Scientist AwardAmira KlipAmira KlipPublished Online:01 Jan 2008https://doi.org/10.1152/ajpendo.00731.2007This is the final version - click for previous versionMoreSectionsPDF (29 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat from time to time, we like to highlight articles authored by winners of the awards offered by the American Physiological Society. The Endocrinology and Metabolism section of APS conferred the 2007 Young Scientist Award to Kei Sakamoto, PhD. Kei is a prolific young scientist who has contributed to the American Journal of Physiology-Endocrinology and Metabolism with numerous publications and by serving on its Editorial Board since January 2007.Kei began his doctoral training at Yokohama City University in his native Japan, but soon transferred to the Joslin Diabetes Center/Harvard Medical School to complete it under the supervision of Dr. Laurie Goodyear. In 2003 he joined the group led by Dr. Dario Alessi at the MRC Protein Phosphorylation Unit of the University of Dundee for further training as a postdoctoral fellow. Since January 2006 he has been a Principal Investigator in the same Unit, and this year he was appointed Head of Molecular Physiology.What is Kei focusing on now? These days it is glycogen metabolism.Muscle glycogen synthesis is stimulated by insulin, and this depends on increased glucose transport and phosphorylation to glucose 6-phosphate, an allosteric activator of glycogen synthase, along with the activation of glycogen synthase by insulin-promoted dephosphorylation of the enzyme on sites Ser641 and Ser645. Insulin achieves the latter by inactivating glycogen synthase kinase-3 (GSK-3). Insulin-stimulated Akt phosphorylates and inactivates both the α- and β-isoforms of GSK-3, thus allowing for a net decrease in glycogen synthase phosphorylation at Ser641/645. Hence, it has been thought that insulin stimulates glycogen synthesis largely by dephosphorylating glycgen synthase through the PI3K-PKB-GSK-3 pathway. The study by Sakamoto and colleagues (1), highlighted below, provides genetic evidence that the insulin-stimulated muscle can synthesize glycogen normally in the absence of this system.The story began with a previous study in which Kei participated as a postodoctoral fellow in the group of Dr. Dario Alessi. McManus, Sakamoto, Alessi, and colleagues created a genetically modified homozygous mouse model in which the two endogenous GSK-3 genes had been eliminated and replaced, through gene knockin (KI), by corresponding genes encoding mutations at the NH2-terminal phosphorylation sites [from serine to alanine residues (2)]. The clear advantage of such a model is the complete replacement of the wild-type kinases with constitutively active forms whose expression is transcriptionally regulated by the wild-type GSK-3 gene promoters.Sakamoto and colleagues [Bouskila et al. (1)] now took advantage of that mouse model to show that, compared with wild-type littermates, muscles from these KI mice have similar glycogen content in the fasted and fed state or following a bolus injection of glucose, despite lack of insulin-stimulated glycogen synthase activity. The muscles from the KI mice also had similar rates of glycogen accumulation compared with controls 1 or 2 h after exposure to insulin in vitro. As well, insulin increased normally both glucose transport and glucose 6-phosphate levels in KI mice. Furthermore, KI mice did not have compensatory alterations in glycogen metabolism muscle phosphorylase activity and responded normally to epinephrine by inhibition of glycogen synthase and stimulation of glycogen phosphorylase. The authors suggest, by extrapolation of the results, that glucose 6-phosphate may be the major regulator of insulin-stimulated glycogen accumulation. This is an intriguing proposition that will likely elicit further direct analysis, a challenge that Kei Sakamoto contemplates, probably along with many of our reader experts in this area.We are pleased to highlight the work of this young scientist and hope that it will inspire young investigators in pursuit of the intricacies of endocrinology and metabolism.REFERENCES1 Bouskila M, Hirshman M, Jensen J, Goodyear L, Sakamoto K. Insulin promotes glycogen synthesis in the absence of GSK3 phosphorylation in skeletal muscle. Am J Physiol Endocrinol Metab (November 6, 2007). doi:10.1152/ajpendo.0407.2007.Google Scholar2 McManus EJ, Sakamoto K, Armit LJ, Ronaldson L, Shapiro N, Marquez R, Alessi DR. Role that phosphorylation of GSK3 plays in insulin and Wnt signalling defined by knockin analysis. EMBO J 24: 1571–1583, 2005.Crossref | PubMed | ISI | Google ScholarAUTHOR NOTESAddress for reprint requests and other correspondence: A. Klip, Division of Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 1X8 Canada (e-mail: [email protected]) Download PDF Previous Back to Top Next FiguresReferencesRelatedInformation More from this issue > Volume 294Issue 1January 2008Pages E27-E27 Copyright & PermissionsCopyright © 2008 by American Physiological Societyhttps://doi.org/10.1152/ajpendo.00731.2007PubMed18042667History Published online 1 January 2008 Published in print 1 January 2008 Metrics

Drosophila mojoless, a Retroposed GSK-3, Has Functionally Diverged to Acquire an Essential Role in Male Fertility

Retroposition is increasingly recognized as an important mechanism for the acquisition of new genes. We show that a glycogen synthase kinase-3 gene, shaggy (sgg), retroposed at least 50 MYA in the Drosophila genus to generate a new gene, mojoless (mjl). We have extensively analyzed the function of mjl and examined its functional divergence from the parental gene sgg in Drosophila melanogaster. Unlike Sgg, which is expressed in many tissues of both sexes, Mjl is expressed specifically in the male germ line, where it is required for male germ line survival. Our analysis indicates that mjl has acquired a specific function in the maintenance of male germ line viability. However, it has not completely lost its ancestral biochemical function and can partially compensate for loss of the parental gene sgg when ectopically expressed in somatic cells. We postulate that mjl has undergone functional diversification and is now under stabilizing selection in the Drosophila genus.

Active glycogen synthase kinase-3 gene transfer inhibits smooth muscle proliferation and neointima formation after balloon injury in rats

Active glycogen synthase kinase-3 gene transfer inhibits smooth muscle proliferation and neointima formation after balloon injury in rats