Enzyme Glycogen Synthase Kinase Research Articles

Characterizing the effects of muscle-specific GSK3α/β reduction on murine muscle contractility and metabolism in female mice.

Dysregulation of skeletal muscle morphology and metabolism is associated with chronic diseases such as obesity and type 2 diabetes. The enzyme glycogen synthase kinase 3 (GSK3) is highly involved in skeletal muscle physiology and metabolism, acting as a negative regulator of muscle size, strength, adaptive thermogenesis, and glucose homeostasis. Correspondingly, we have shown that partial knockdown (∼40%) of GSK3 specifically in skeletal muscle increases lean mass, reduces fat mass, and activates muscle-based adaptive thermogenesis via sarco(endo)plasmic reticulum Ca2+ (SERCA) uncoupling in male mice. However, the effects of GSK3 knockdown in female mice have yet to be investigated. Here, we examined the effects of muscle-specific GSK3 knockdown on body composition, muscle size and strength, and whole body metabolism in female C57BL/6J mice. Our results show that GSK3 content is higher in the female soleus versus the male soleus; however, there were no differences in the extensor digitorum longus (EDL). Furthermore, muscle-specific GSK3 knockdown did not alter body composition in female mice, nor did it alter daily energy expenditure, glucose/insulin tolerance, mitochondrial respiration, or the expression of the SERCA uncouplers sarcolipin and neuronatin. We also did not find any differences in soleus muscle size, strength, or fatigue resistance. In the EDL, we found that an increase in absolute and specific force production, but there were no differences in fatigability. Therefore, our study highlights sex differences in the response to genetic reduction of gsk3, with most of the effects previously observed in male mice being absent in females.NEW & NOTEWORTHY Here we show that partial GSK3 knockdown has minimal effects on whole body metabolism and muscle contractility in female mice. This is partly inconsistent with previous results found in male mice, which reveal a potential influence of biological sex.

Low-Dose Lithium Supplementation Influences GSK3β Activity in a Brain Region Specific Manner in C57BL6 Male Mice.

Lithium, a commonly used treatment for bipolar disorder, has been shown to have neuroprotective effects for other conditions including Alzheimer's disease via the inhibition of the enzyme glycogen synthase kinase-3 (GSK3). However, dose-dependent adverse effects of lithium are well-documented, highlighting the need to determine if low doses of lithium can reliably reduce GSK3 activity. The purpose of this study was to evaluate the effects of a low-dose lithium supplementation on GSK3 activity in the brain of an early, diet-induced Alzheimer's disease model. Male C57BL/6J mice were divided into either a 6-week or 12-week study. In the 6-week study, mice were fed a chow diet or a chow diet with lithium-supplemented drinking water (10 mg/kg/day) for 6 weeks. Alternatively, in the 12-week study, mice were fed a chow diet, a high-fat diet (HFD), or a HFD with lithium-supplemented drinking water for 12 weeks. Prefrontal cortex and hippocampal tissues were collected for analysis. Results demonstrated reduced GSK3 activity in the prefrontal cortex as early as 6 weeks of lithium supplementation, in the absence of inhibitory phosphorylation changes. Further, lithium supplementation in an obese model reduced prefrontal cortex GSK3 activity as well as improved insulin sensitivity. Collectively, these data provide evidence for low-dose lithium supplementation to inhibit GSK3 activity in the brain. Moreover, these results indicate that GSK3 activity can be inhibited despite any changes in phosphorylation. These findings contribute to an overall greater understanding of low-dose lithium's ability to influence GSK3 activity in the brain and its potential as an Alzheimer's disease prophylactic.

Glycogen synthase kinase-3 (GSK-3) a magic enzyme: it's role in diabetes mellitus and glucose homeostasis, interactions with fluroquionlones. A mini-review.

Diabetes mellitus (DM) is a non-communicable disease throughout the world in which there is persistently high blood glucose level from the normal range. The diabetes and insulin resistance are mainly responsible for the morbidities and mortalities of humans in the world. This disease is mainly regulated by various enzymes and hormones among which Glycogen synthase kinase-3 (GSK-3) is a principle enzyme and insulin is the key hormone regulating it. The GSK-3, that is the key enzyme is normally showing its actions by various mechanisms that include its phosphorylation, formation of protein complexes, and other cellular distribution and thus it control and directly affects cellular morphology, its growth, mobility and apoptosis of the cell. Disturbances in the action of GSK-3 enzyme may leads to various disease conditions that include insulin resistance leading to diabetes, neurological disease like Alzheimer's disease and cancer. Fluoroquinolones are the most common class of drugs that shows dysglycemic effects via interacting with GSK-3 enzyme. Therefore, it is the need of the day to properly understand functions and mechanisms of GSK-3, especially its role in glucose homeostasis via effects on glycogen synthase.

The Tumor Suppressor Protein TRAF3 Modulates GSK3 Activity and Susceptibility of B Lymphoma Cells to GSK3 Inhibition.

Simple SummaryTRAF3 is an adapter protein that regulates signals through many receptors important for B cell differentiation and function. Loss-of-function mutations or deletions of TRAF3 are common in B cell malignancies. Glycogen Synthase Kinase 3 (GSK3) regulates signaling in growth, survival, and metabolism pathways. GSK3 inhibitors have been effective against many solid tumors; the inhibitor used in this work is currently being tested for efficacy against BCLs. We found that TRAF3 and GSK3 associate in multiple BCL cell lines, and that BCLs with low TRAF3 have a higher susceptibility to GSK3 inhibition. In contrast to BCL cell lines, GSK3 inhibition has little effect on TRAF3-sufficient and deficient resting primary B cells. These results suggest TRAF3 level as a predictor of BCL responsiveness to GSK3 inhibitor therapy.TNF receptor-associated factor 3 (TRAF3) is an adapter protein that inhibits many signals that promote B cell survival and activation. Mice with a B cell-specific TRAF3 deficiency and humans with a rare haploinsufficiency in TRAF3 have enhanced development of BCLs as they age. Loss-of-function mutations in TRAF3 are common in B cell malignancies. Recent studies show that pharmacological inhibition of the enzyme glycogen synthase kinase 3 (GSK3), which regulates cellular growth, survival, and metabolism, inhibits growth and survival of BCL-derived B cells. In this study, we found that TRAF3 and GSK3 associated in B cells. The relative levels of TRAF3 in BCL cell lines correlated positively with the ratio of inactive to total GSK3β, and negatively correlated with susceptibility to GSK3 inhibition by the GSK3 inhibitory drug 9-ING-41, currently in clinical trials. Uniquely in BCLs with low TRAF3, GSK3 inhibition caused increased loss of the TRAF3-regulated, anti-apoptotic protein Mcl-1. GSK3 inhibition also blocked hyperresponsiveness to IL-6 receptor signaling in TRAF3-deficient BCL cells. Together, these results support the utility of 9-ING-41 as a treatment for BCL, and suggest that a decrease or loss of TRAF3 in BCLs could act as a biomarker for increased susceptibility to GSK3 inhibitor treatment.

GSK-3β-mediated regulation of Nrf2/HO-1 signaling as a new therapeutic approach in the treatment of movement disorders.

Movement disorders are neurological conditions characterized by involuntary motor movements, such as dystonia, ataxia, chorea myoclonus, tremors, Huntington's disease (HD), and Parkinson's disease (PD). It is classified into two categories: hypokinetic and hyperkinetic movements. Globally, movement disorders are a major cause of death. The pathophysiological process is initiated by excessive ROS generation, mitochondrial dysfunction, neuroinflammation, and neurotransmitters imbalance that lead to motor dysfunction in PD and HD patients. Several endogenous targets including Nrf2 maintain oxidative balance in the body. Activation of Nrf2 signaling is regulated by the enzyme glycogen synthase kinase (GSK-3β). In the cytoplasm, inhibition of GSK-3β regulates cellular proliferation, homeostasis, and apoptotic process by stimulating the nuclear factor erythroid 2 (Nrf2) pathway which is involved in the elevation of the cellular antioxidant enzymes which controls the ROS generation. The activation of Nrf2 increases the expression of antioxidant response elements (ARE), such as (Hemeoxygenase-1) HO-1, which decreases excessive cellular stress, mitochondrial dysfunction, apoptosis, and neuronal degeneration, which is the major cause of motor dysfunction. The present review explores the GSK-3β-mediated neuroprotection in various movement disorders through the Nrf2/HO-1 antioxidant pathway. This review provides alink between GSK-3β and the Nrf2/HO-1 signaling pathway in the treatment of PD and HD. In addition to that it highlights various GSK-3β inhibitors and the Nrf2/HO-1 activators, which exert robust neuroprotection against motor disorders. Therefore, the present review will help in the discovery of new therapy for PD and HD patients.

Tideglusib inhibition of GSK3 promotes the oxidative muscle phenotype and reduces serum creatine kinase in D2 mdx mice

Introduction Duchenne muscular dystrophy (DMD) is an X-linked disorder caused by an absence of dystrophin that compromises membrane integrity, ultimately resulting in muscle weakness, wasting, and premature death. The fast glycolytic muscle fibres are known to be most susceptible to dystrophic pathology, while slow oxidative fibres are less affected. Thus, promoting the slow oxidative phenotype has become a viable therapeutic strategy. Recent work from our lab has shown that inhibiting the enzyme glycogen synthase kinase 3 (GSK3) can promote the slow oxidative phenotype leading to enhancements in fatigue resistance. Furthermore, we have shown that inhibiting GSK3 augments muscle specific force production and myoblast fusion. Therefore, inhibiting GSK3 may aid in alleviating dystrophic pathology. Tideglusib is a potent GSK3 inhibitor currently undergoing clinical trials for myotonic dystrophy, another form of muscular dystrophy. Here, we tested whether treating the DMD preclinical mdx mouse with tideglusib would alter muscle oxidative phenotype, improve muscle function, and reduce serum creatine kinase (CK) levels, a marker of cellular damage. Methods Male DBA/2J wild type (WT) and mdx mice were ordered from Jackson Laboratories at 5-6 weeks of age. Three groups were included in this study; 1) WT healthy control, 2) mdx tideglusib (10 mg/kg/day, via oral gavage), and 3) mdx vehicle (26% peg400, 15% Chremaphor EL and water). The mdx-tideglusib and vehicle mice underwent their respective treatments for 2 weeks with ad libitum access to food and water. Subsequently, all mice were subjected to a hangwire test to assess muscle function. Mice were then euthanized and their serum extracted for CK activity analyses using a commercially available kit that was fitted onto a 96-well plate. Extensor digitorum longus (EDL) muscles were collected and homogenized for Western blotting to investigate phosphorylated (serine 9) and total GSK3b content along with myosin heavy chain (MHC) I and IIa levels. Results The hangwire test results showed that mdx mice treated with tideglusib were able to sustain hanging on the wire for a significantly longer period of time compared with the mdx vehicle group (p = 0.03). Serum CK analyses revealed that while the mdx vehicle group had significantly higher levels of activity compared with WT (p = 0.009), there was a 30% reduction in the mdx tideglusib mice that was no longer significantly different from WT. Western blotting revealed that though phosphorylated GSK3b levels were unaltered, tideglusib treatment led to a significant reduction in GSK3b content compared with vehicle (p = 0.04). Additionally, there was a significant increase in the oxidative MHC isoforms (I and IIa, p = 0.02) in the mdx tideglusib group compared with vehicle. Conclusions Our results demonstrate the potential use of tideglusib for DMD. We show that tideglusib treatment inhibited GSK3 in mdx mice through a reduction in total GSK3 content. In turn, we also found a significant increase in oxidative MHC isoforms (I and IIa), which was associated with enhanced muscle performance and reduced muscle damage.

GSK3α: An Important Paralog in Neurodegenerative Disorders and Cancer

The biological activity of the enzyme glycogen synthase kinase-3 (GSK3) is fulfilled by two paralogs named GSK3α and GSK3β, which possess both redundancy and specific functions. The upregulated activity of these proteins is linked to the development of disorders such as neurodegenerative disorders (ND) and cancer. Although various chemical inhibitors of these enzymes restore the brain functions in models of ND such as Alzheimer’s disease (AD), and reduce the proliferation and survival of cancer cells, the particular contribution of each paralog to these effects remains unclear as these molecules downregulate the activity of both paralogs with a similar efficacy. Moreover, given that GSK3 paralogs phosphorylate more than 100 substrates, the simultaneous inhibition of both enzymes has detrimental effects during long-term inhibition. Although the GSK3β kinase function has usually been taken as the global GSK3 activity, in the last few years, a growing interest in the study of GSK3α has emerged because several studies have recognized it as the main GSK3 paralog involved in a variety of diseases. This review summarizes the current biological evidence on the role of GSK3α in AD and various types of cancer. We also provide a discussion on some strategies that may lead to the design of the paralog-specific inhibition of GSK3α.

Proposition of Potential GSK-3β Inhibitors for the Treatment of Alzheimer's Disease: A Molecular Modeling Study.

The enzyme Glycogen Synthase Kinase 3-β (GSK-3β) is related to neuronal cell degeneration, representing a promising target to treat Alzheimer's Disease (AD). In this work, we performed a molecular modeling study of existing GSK-3β inhibitors by means of evaluation of their IC50 values, derivation of a pharmacophore model, molecular docking simulations, ADME/Tox properties predictions, molecular modifications and prediction of synthetic viability. In this manner, inhibitor 15 (CID 57399952) was elected a template molecule, since it demonstrated to bear relevant structural groups able to interact with GSK-3β, and also presented favorable ADME/Tox predicted properties, except for mutagenicity. Based on this inhibitor chemical structure we proposed six analogues that presented the absence of alerts for mutagenic and carcinogenic activity, both for rats and mouse; likewise they all presented low risk alerts for inhibition of hERG and medium prediction of synthetic viability. It is concluded that the analogues of GSK-3β inhibitors were optimized in relation to the toxicity endpoint of the template molecule, being, therefore, presented as novel and promising drug candidates for AD treatment.

Low-dose lithium feeding increases the SERCA2a-to-phospholamban ratio, improving SERCA function in murine left ventricles.

What is the central question of this study? Inhibition of glycogen synthase kinase-3 (GSK3) has been shown to improve cardiac SERCA2a function. Lithium can inhibit GSK3, but therapeutic doses used in treating bipolar disorder can have toxic effects. It has not been determined whether subtherapeutic doses of lithium can improve cardiac SERCA function. What is the main finding and its importance? Using left ventricles from wild-type mice, we found that subtherapeutic lithium feeding for 6weeks decreased GSK3 activity and increased cardiac SERCA function compared with control-fed mice. These findings warrant the investigation of low-dose lithium feeding in preclinical models of cardiomyopathy and heart failure to determine the therapeutic benefit of GSK3 inhibition. The sarco(endo)plasmic reticulum Ca2+ -ATPase (SERCA) pump is responsible for regulating calcium (Ca2+ ) within myocytes, with SERCA2a being the dominant isoform in cardiomyocytes. Its inhibitor, phospholamban (PLN), acts by decreasing the affinity of SERCA for Ca2+ . Changes in the SERCA2a:PLN ratio can cause Ca2+ dysregulation often seen in patients with dilated cardiomyopathy and heart failure. The enzyme glycogen synthase kinase-3 (GSK3) is known to downregulate SERCA function by decreasing the SERCA2a:PLN ratio. In this study, we sought to determine whether feeding mice low-dose lithium, a natural GSK3 inhibitor, would improve left ventricular SERCA function by altering the SERCA2a:PLN ratio. To this end, male wild-type C57BL/6J mice were fed low-dose lithium via drinking water (10mgkg-1 day-1 LiCl for 6weeks) and left ventricles were harvested. GSK3 activity was significantly reduced in LiCl-fed versus control-fed mice. The apparent affinity of SERCA for Ca2+ was also increased (pCa50 ; control, 6.09±0.03 versus LiCl, 6.26±0.04, P<0.0001) along with a 2.0-fold increase in SERCA2a:PLN ratio in LiCl-fed versus control-fed mice. These findings suggest that low-dose lithium supplementation can improve SERCA function by increasing the SERCA2a:PLN ratio. Future studies in murine preclinical models will determine whether GSK3 inhibition via low-dose lithium could be a potential therapeutic strategy for dilated cardiomyopathy and heart failure.

Glycogen synthase kinase-3 inhibition as a potential pharmacological target for vascular dementia: In silico and in vivo evidence

Vascular dementia is a serious problem as it creates significant disability and dependency in the affected person. Lives of these patients can be improved through the advent of novel drug targets which can be targeted by pharmacological therapies. However, finding a precise and druggable target for vascular dementia is experimentally impossible and challenging task owing to a complex and mostly unknown interplay between the cognitive abilities of the brain with a diversity of vascular diseases. To address this issue, we have systematically analyzed the literature reports by using well-known methods and approaches of bioinformatics (viz. network pharmacology, reverse pharmacology, enrichment analysis of KEGG pathways, biological processes of Gene Ontology and DIAMOnD algorithm). Because glycogen synthase kinase-3 (GSK-3) seems to be one of the most promising targets, therefore, we have tested the capacity of lithium carbonate, a classical inhibitor of GSK-3, for treatment of dementia resulting from mild chronic cerebral hypoperfusion in mice. To this end, our study shows in-vivo validation of predicted target, i.e., pharmacological deactivation of GSK-3 enzyme and its impact on cognitive abilities employing a behavioral test battery, i.e., object recognition task, step-through passive avoidance task, elevated plus maze task and water maze task. In this framework, we observed that lithium carbonate attenuates recognition, emotion, spatial and fear-motivated learning and memory impairments along with attenuation of oxidative stress, cholinergic dysfunction and glutamate-induced excitotoxicity in cerebral cortex and hippocampus. In conclusion, we propose GSK-3 as a promising drug target for vascular dementia in light of experimental results and in-silico predictions.

Podocyte GSK3 is an evolutionarily conserved critical regulator of kidney function

Albuminuria affects millions of people, and is an independent risk factor for kidney failure, cardiovascular morbidity and death. The key cell that prevents albuminuria is the terminally differentiated glomerular podocyte. Here we report the evolutionary importance of the enzyme Glycogen Synthase Kinase 3 (GSK3) for maintaining podocyte function in mice and the equivalent nephrocyte cell in Drosophila. Developmental deletion of both GSK3 isoforms (α and β) in murine podocytes causes late neonatal death associated with massive albuminuria and renal failure. Similarly, silencing GSK3 in nephrocytes is developmentally lethal for this cell. Mature genetic or pharmacological podocyte/nephrocyte GSK3 inhibition is also detrimental; producing albuminuric kidney disease in mice and nephrocyte depletion in Drosophila. Mechanistically, GSK3 loss causes differentiated podocytes to re-enter the cell cycle and undergo mitotic catastrophe, modulated via the Hippo pathway but independent of Wnt-β-catenin. This work clearly identifies GSK3 as a critical regulator of podocyte and hence kidney function.

GSK-3 Inhibitors: From theBrain to theRetina and Back Again.

Enzyme glycogen synthase kinase-3 (GSK-3) is a candidate pharmacological target for the treatment of neurodegenerative diseases of the brain. Given the many molecular, cellular, and functional features shared by the brain and the retina in both physiological and pathological processes, drugs originally designed to treat neurodegenerative diseases of the brain could be useful candidates for the treatment of retinal degenerative pathologies. Moreover, the accessibility of the eye to noninvasive, quantitative diagnostic techniques allows for easier evaluation of the efficacy of candidate therapies in clinical trials. In this chapter, we discuss the potential of GSK-3 inhibitors in the treatment of retinal degeneration.

NO-sGC-cGMP signaling influence the anxiolytic like effect of lithium in mice in light and dark box and elevated plus maze

Glutamate is an excitatory neurotransmitter implicated in the pathogenesis of psychiatric disorders. Glutamate results in the activation of an enzyme called glycogen synthase kinase-3 (GSK-3) acting through N-methyl-d-aspartate (NMDA) receptors. Impaired expression of GSK-3 affects behavior and neurochemicals level in the brain responsible for the pathogenesis of mood disorders. It has been reported that lithium acts as an inhibitor of GSK-3 and inhibit the enzyme GSK-3 in an uncompetitive manner. In the present study, anxiolytic like effect of lithium in mice is investigated through light and dark box (LDB) and elevated plus maze (EPM). Lithium (50, 100 and 200 mg/kg, i.p.) was administered to the mice to determine the anxiety related behavior. Results obtained suggests that the administration of lithium (100 mg/kg, i.p.) reversed the anxiety related behavior of mice and decreased the levels of glutamate and nitrite as compared to control. Glutamate acting through the NMDA receptor has been found to regulate the expression of enzyme neuronal nitric oxide synthase (nNOS), which is responsible for the release of nitric oxide (NO), suggesting a possible link between NO and GSK-3 also. Therefore, to determine the possible interaction with NO, sub-effective dose of lithium was administered in combination with NO donor i.e. l-Arginine (50 mg/kg, i.p.), NOS and soluble guanylate cyclase (sGC) inhibitor i.e. methylene blue (1 mg/kg, i.p.) and phosphodiesterase inhibitor i.e. sildenafil (1 mg/kg, i.p.). The results obtained demonstrated that the anxiolytic like effect of lithium was abolished by the pretreatment with NO donor and potentiated by the pretreatment with NOS inhibitor. Therefore, it is suggested that NO signaling pathway influence the anxiolytic like activity of lithium in mice, further suggesting the link between the GSK-3 and NO signaling in the regulation of anxiety related behavior.

Abstract 1696: Glycogen synthase kinase (GSK-3) inactivation downregulates PD-1 and synergizes with PD-1/PL1 and CTLA-4 blockade in cancer immunotherapy

Abstract Immune checkpoint blockade (ICB) of negative co-receptors on T-cells such as cytotoxic T-cell antigen-4 (CTLA-4) and programmed cell death-1 (PD-1) is a promising approach for the treatment of cancer. Despite this success, the poor prognosis for most patients continues to highlight a need for developing novel clinical interventions. In this context, we identified the enzyme glycogen synthase kinase-3 (GSK-3) as the major regulator of PD-1 expression on T-cells (Taylor et al., 2016 Immunity). We have shown that small molecule inhibitors (SMIs) of GSK-3 are as effective as anti-PD-1 in controlling the growth of B16 melanoma, or EL4 lymphoma, in primary tumor and metastatic settings (Taylor et al., 2017 Can Res; Krueger and Rudd, Immunity 2017). At the same time, the fact that GSK-3 inactivation up-regulates transcription factor T-bet which upregulates interferon gamma (IFNγ) and granzyme B (GZMB) suggested that GSK-3 inactivation might provide extra value beyond of its down-regulation of PD-1. Here, we show that GSK-3 SMIs can synergize with anti-PD-1 and anti-CTLA-4 to eliminate B16 solid tumors that are otherwise resistant to anti-PD-1, or anti-CTLA-4 inhibition alone. At a cellular level, GSK-3 inactivation preferentially down-regulated PD-1 on CD8+ tumor infiltrating T-cells, while at a molecular level, GSK-3 SMIs inhibited PD-1 transcription, increased granzyme B (GZMB)/ interferon-gamma1 (IFNγ) transcription and directly acted upon glycogen synthase to skew metabolism towards greater glycolysis. We further showed that the inactivation of GSK-3α/β through siRNA or by SMIs substituted for CD28 co-stimulation in the potentiation of cytotoxic CD8+ CTL function. This data supports a model where GSK-3 mediates the dependency of anti-PD-1 immunotherapy on the expression of CD28. Overall, our data show that GSK-3 inactivation is an immune-sensitizer which assists the immune system to overcome tumor resistance to immune check-point blockade. Citation Format: Christopher E. Rudd. Glycogen synthase kinase (GSK-3) inactivation downregulates PD-1 and synergizes with PD-1/PL1 and CTLA-4 blockade in cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1696.

INIBIDORES DA GSK-3: UMA NOVA ESTRATÉGIA PARA A REGENERAÇÃO DENTAL

A enzima GSK-3 (glicogênio sintase quinase 3) regula múltiplas etapas da bioquímica celular e alterações em sua atividade estão envolvidas em diversas doenças. Desde a década de 1990, a GSK-3 tornou-se importante sítio-alvo para o desenvolvimento de novos fármacos e vários inibidores foram avaliados para o tratamento de diversas patologias como diabetes e doença de Alzheimer. O tideglusibe é um inibidor da GSK-3 planejado para o tratamento da doença de Alzheimer. Recentemente, ficou demonstrado que esse fármaco pode induzir a reparação natural da polpa dental por meio da ativação de células estaminais, levando à regeneração do material dentário da área danificada. Esse processo de regeneração natural representa uma inovação entre as técnicas de restauração dentária ao estimular a multiplicação das células da polpa dental e conduzir à vedação de pequenas cavidades. O objetivo desse artigo é apresentar uma revisão do papel da enzima GSK-3, seus inibidores e os efeitos do tideglusibe na regeneração dental.

Sol-gel derived lithium-releasing glass for cartilage regeneration.

Wnt-signalling cascade is one of the crucial pathways involved in the development and homeostasis of cartilage. Influencing this pathway can potentially contribute to improved cartilage repair or regeneration. One key molecular regulator of the Wnt pathway is the glycogen synthase kinase-3 enzyme, the inhibition of which allows initiation of the signalling pathway. This study aims to utilise a binary SiO2-Li2O sol-gel derived glass for controlled delivery of lithium, a known glycogen synthase kinase-3 antagonist. The effect of the dissolution products of the glass on chondrogenic differentiation in an invitro 3D pellet culture model is reported. Dissolution products that contained 5 mM lithium and 3.5 mM silicon were capable of inducing chondrogenic differentiation and hyaline cartilaginous matrix formation without the presence of growth factors such as TGF-β3. The results suggest that sol-gel derived glass has the potential to be used as a delivery vehicle for therapeutic lithium ions in cartilage regeneration applications.

Wnt and GSK3 Signaling Pathways in Bipolar Disorder: Clinical and Therapeutic Implications.

The neurobiology of bipolar disorder, a chronic and systemic ailment is not completely understood. The bipolar phenotype manifests in myriad ways, and psychopharmacological agents like lithium have long term beneficial effects. The enzyme glycogen synthase kinase 3 (GSK3) has come into focus, as lithium and several other mood stabilizing medications inhibit its activity. This kinase and its key upstream modulator, Wnt are dysregulated in mood disorders and there is a growing impetus to delineate the chief substrates involved in the development of these illnesses. In May 2016, a comprehensive literature search was undertaken which revealed that there is over activity of GSK3 in bipolar disorder with deleterious downstream effects like proinflammatory status, increased oxidative stress, and circadian dysregulation leading to declining neurotrophic support and enhanced apoptosis of neural elements. By developing specific GSK3 inhibitors the progressive worsening in bipolar disorder can be forestalled with improved prospects for the sufferers.

Roles of GSK-3 and microRNAs on epithelial mesenchymal transition and cancer stem cells.

Various signaling pathways exert critical roles in the epithelial to mesenchymal transition (EMT) and cancer stem cells (CSCs). The Wnt/beta-catenin, PI3K/PTEN/Akt/mTORC, Ras/Raf/MEK/ERK, hedgehog (Hh), Notch and TP53 pathways elicit essential regulatory influences on cancer initiation, EMT and progression. A common kinase involved in all these pathways is moon-lighting kinase glycogen synthase kinase-3 (GSK-3). These pathways are also regulated by micro-RNAs (miRs). TP53 and components of these pathways can regulate the expression of miRs. Targeting members of these pathways may improve cancer therapy in those malignancies that display their abnormal regulation. This review will discuss the interactions of the multi-functional GSK-3 enzyme in the Wnt/beta-catenin, PI3K/PTEN/Akt/mTORC, Ras/Raf/MEK/ERK, Hh, Notch and TP53 pathways. The regulation of these pathways by miRs and their effects on CSC generation, EMT, invasion and metastasis will be discussed.

CCND1 Mutations Increase Protein Stability and Promote Ibrutinib Resistance in Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) represents 6-8% of non-Hodgkin's lymphoma with a median survival of 3-5 years. CyclinD1 (CCND1) chromosomal translocation t(11;14) is the hallmark of this neoplasm, which leads to its deregulated expression. Recent knock down studies of CCND1 in MCL have shown that its role is not only limited to promote cell cycle progression but also for maintaining genomic stability. Knock down of CCND1 results in increased DNA damage in MCL cells and makes them more susceptible to chemotherapy. However, CCND1 is not only prone to frequent translocation but also to somatic mutations. Genomic studies have identified recurring somatic mutations in the coding region of CCND1 in approximately 30% of MCL cases. The hot spot of these mutations is concentrated in exon 1 of CCND1. However, the functional consequence of these mutations is not known. We generated the most common CCND1 mutations (E36K, Y44D or C47S) by site directed mutagenesis and overexpressed these mutants in JEKO-1, UPN-1 or Z-138 MCL cell lines. Here, we show that these single mutations, as compared to the wild type (WT), increased CCND1 protein levels in MCL cell lines and primary tumors. Mechanistically, mutations Y44D or C47S increase the stability of CCND1 protein through attenuation of threonine-286 phosphorylation, which is a prerequisite for export of CCND1 from the nucleus to the cytoplasm, followed by proteolysis through the ubiquitin-proteasome pathway. But the two mutants have stronger affinity to interact with the threonine-286 phosphorylating enzyme glycogen synthase kinase 3 beta ,whereas interaction with cyclin-dependent kinase 4 remains unaffected. Furthermore we observed that these two mutants are preferentially localized in the nucleus compared to WT, as determined by cell fractionation and immunofluorescence assays. In order to understand the relevance of stable CCND1 protein in MCL, we studied the response of WT or mutant CCND1-expressing MCL cell lines to ibrutinib, an FDA- approved Bruton tyrosine kinase inhibitor used for MCL treatment. We observed that forced expression of WT or mutant CCND1 increased the resistance of JEKO-1 cells to ibrutinib. The Y44D mutation sustained the resistance to ibrutinib at supraphysiologic concentrations (5-10 μM). Furthermore, primary MCL tumors with CCND1 mutations expressed a more stable protein and were resistant to ibrutinib than WT cases. These findings uncover new mechanisms for MCL cells to increase CCND1 protein level through somatic mutations, which may provide a survival advantage to the lymphoma cells in developing resistance against the emerging ibrutinib therapy. DisclosuresPillai:Trillium Therapeutics: Research Funding. Pham:Vyripharm Biopharmaceuticals: Research Funding.

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.