Inhibiting ceramide synthase 5 expression in microglia decreases neuroinflammation after spinal cord injury

Microglia,the resident monocyte of the central nervous system,play a crucial role in the response to spinal cord injury.However,the precise mechanism remains unclear.To investigate the molecular mechanisms by which microglia regulate the neuroinflammatory response to spinal cord injury,we performed single-cell RNA sequencing dataset analysis,focusing on changes in microglial subpopulations.We found that the MG1 subpopulation emerged in the acute/subacute phase of spinal cord injury and expressed genes related to cell pyroptosis,sphingomyelin metabolism,and neuroinflammation at high levels.Subsequently,we established a mouse model of contusive injury and performed intrathecal injection of siRNA and molecular inhibitors to validate the role of ceramide synthase 5 in the neuroinflammatory responses and pyroptosis after spinal cord injury.Finally,we established a PC12-BV2 cell co-culture system and found that ceramide synthase 5 and pyroptosis-associated proteins were highly expressed to induce the apoptosis of neuron cells.Inhibiting ceramide synthase 5 expression in a mouse model of spinal cord injury effectively reduced pyroptosis.Furthermore,ceramide synthase 5-induced pyroptosis was dependent on activation of the NLRP3 signaling pathway.Inhibiting ceramide synthase 5 expression in microglia in vivo reduced neuronal apoptosis and promoted recovery of neurological function.Pla2g7 formed a“bridge”between sphingolipid metabolism and ceramide synthase 5-mediated cell death by inhibiting the NLRP3 signaling pathway.Collectively,these findings suggest that inhibiting ceramide synthase 5 expression in microglia after spinal cord injury effectively suppressed microglial pyroptosis mediated by NLRP3,thereby exerting neuroprotective effects.

Effect of Dexamethasone on Nitric Oxide Synthase and Caspase-3 Gene Expressions in Endotoxemia in Neonate Rat Brain

Objective To investigate the gene and protein expressions of three isoforms of nitric oxide synthase (NOS) and gene expression of Caspase-3, and effect of dexamethasone on them in neonatal rats with lipopolysaccharide (LPS)-induced endotoxemic brain damage. Methods Expressions of the three isoforms of NOS and caspase-3 mRNA in the brain were investigated by RT-PCR in postnatal 7-day wistar rats with acute endotoxemia by intraperitoneal administration of LPS. Regional distributions of NOSs were examined by immunohistochemical technique. Results nNOS and Caspase-3 mRNA were obviously detected. eNOS mRNA was faintly expressed, but iNOS mRNA was undetectable in the control rat brain. The expressions of NOS mRNA of three isoforms were weak 2 h after LPS (5 mg/mg) delivery, peaked at 6 h, and thereafter, reduced gradually up to 24 h. The expression intensity was in the order of nNOS> iNOS> eNOS. Widespread nNOS, scattered eNOS distribution and negative iNOS were identified in the control rat brain and all isoforms of NOS could be induced by LPS which reached the apex at 24 h in the order of nNOS> iNOS> eNOS as detected by immunostaining. Although Caspase-3 mRNA could be found in all groups, DNA fragmentation was only seen at 6 h and 24 h. The expressions of NOS and Caspase-3 mRNA were inhibited in the rat brain when dexamethasone was administrated. Conclusion LPS-induced NO production induces apoptosis of neurons through mechanism involving the Caspase-3 activation, which may play an important role in the pathogenesis of brain damage during endotoxemia, and neuro-protective effects of dexamethasone may be partially realized by inhibiting the expression of NOS mRNA.

Glycogen synthase kinase-3β positively regulates the proliferation of human ovarian cancer cells

Although glycogen synthase kinase-3 （GSK-3） might act as a tumor suppressor since its inhibition is expected to mimic the activation of Wnt-signaling pathway, GSK-3β may contribute to NF-κB activation in cancer cells leading to increased cancer cell proliferation and survival. Here we report that GSK-3β activity was involved in the proliferation of human ovarian cancer cell both in vitro and in vivo. Inhibition of GSK-3 activity by pharmacological inhibitors suppressed proliferation of the ovarian cancer cells. Overexpressing constitutively active form of GSK-3β induced entry into the S phase, increased cyclin D1 expression and facilitated the proliferation of ovarian cancer cells. Furthermore, GSK-3 inhibition prevented the formation of the tumor in nude mice generated by the inoculation of human ovarian cancer cells. Our findings thus suggest that GSK-3β activity is important for the proliferation of ovarian cancer cells, implicating this kinase as a potential therapeutic target in ovarian cancer.

Lithium chloride ameliorates learning and memory ability and inhibits glycogen synthase kinase-3 beta activity in a mouse model of fragile X syndrome

In the present study,Fmr1 knockout mice （KO mice） were used as the model for fragile X syndrome.The results of step-through and step-down tests demonstrated that Fmr1 KO mice had shorter latencies and more error counts,indicating a learning and memory disorder.After treatment with 30,60,90,120,or 200 mg/kg lithium chloride,the learning and memory abilities of the Fmr1 KO mice were significantly ameliorated,in particular,the 200 mg/kg lithium chloride treatment had the most significant effect.Western blot analysis showed that lithium chloride significantly enhanced the expression of phosphorylated glycogen synthase kinase 3 beta,an inactive form of glycogen synthase kinase 3 beta,in the cerebral cortex and hippocampus of the Fmr1 KO mice.These results indicated that lithium chloride improved learning and memory in the Fmr1 KO mice,possibly by inhibiting glycogen synthase kinase 3 beta activity.

Cornel iridoid glycoside induces autophagy to protect against tau oligomer neurotoxicity induced by activation of glycogen synthase kinase-3β

Tau oligomers are the etiologic molecules of Alzheimer disease(AD), and correlate strongly with neuronal loss and exhibit neurotoxicity. Recent evidence indicates that small tau oligomers are the most relevant toxic aggregate species. The aim of the present study was to investigate the mechanisms of cornel iridoid glycoside(CIG) on tau oligomers and cognitive functions. We injected wortmannin and GF-109203 X(WM/GFX, 200 μmol·L-1 each) into the lateral ventricles to induce tau oligomer and memory impairment in rats. When oral y administered with CIG at 60 and 120 mg·kg-1 per day for 14 d, CIG decreased the escape latency in Morris water maze test. We also found that CIG restored the expression of presynaptic p-synapsin, synaptophysin, and postsynaptic density-95(PSD-95) decreased by WM/GFX in rat cortex. CIG reduced the accumulation of tau oligomers in the brain of WM/GFX rats and in cells transfected with wild type glycogen synthase kinase-3β(wt GSK-3β). In addition, CIG up-regulated the levels of ATG7, ATG12, Beclin-1, and LC3 II in vivo and in vitro, suggesting the restoration of autophagy function. These results suggest that CIG could ameliorate memory deficits and regulate memory-associated synaptic proteins through the clearance of tau oligomers accumulation. Moreover, CIG clears tau oligomers by restoring autophagy function.

The role of glycogen synthase kinase 3 beta in brain injury induced by myocardial ischemia/reperfusion injury in a rat model of diabetes mellitus

Myocardial ischemia/reperfusion injury can lead to severe brain injury.Glycogen synthase kinase 3 beta is known to be involved in myocardial ischemia/reperfusion injury and diabetes mellitus.However,the precise role of glycogen synthase kinase 3 beta in myocardial ischemia/reperfusion injury-induced brain injury is unclear.In this study,we observed the effects of glycogen synthase kinase 3 beta on brain injury induced by myocardial ischemia/reperfusion injury in diabetic rats.Rat models of diabetes mellitus were generated via intraperitoneal injection of streptozotocin.Models of myocardial ischemia/reperfusion injury were generated by occluding the anterior descending branch of the left coronary artery.Post-conditioning comprised three cycles of ischemia/reperfusion.Immunohistochemical staining and western blot assays demonstrated that after 48 hours of reperfusion,the structure of the brain was seriously damaged in the experimental rats compared with normal controls.Expression of Bax,interleukin-6,interleukin-8,terminal deoxynucleotidyl transferase d UTP nick end labeling,and cleaved caspase-3 in the brain was significantly increased,while expression of Bcl-2,interleukin-10,and phospho-glycogen synthase kinase 3 beta was decreased.Diabetes mellitus can aggravate inflammatory reactions and apoptosis.Ischemic post-conditioning with glycogen synthase kinase 3 beta inhibitor lithium chloride can effectively reverse these changes.Our results showed that myocardial ischemic post-conditioning attenuated myocardial ischemia/reperfusion injury-induced brain injury by activating glycogen synthase kinase 3 beta.According to these results,glycogen synthase kinase 3 beta appears to be an important factor in brain injury induced by myocardial ischemia/reperfusion injury.

Glycogen Synthase Kinase-3β,NLRP3 Inflammasome,and Alzheimer's Disease

Alzheimer’s disease (AD) is the most prevalent cause of dementia worldwide. Because of the progressive neurodegeneration, individual cognitive and behavioral functions are impaired, affecting the quality of life of millions of people. Although the exact pathogenesis of AD has not been fully elucidated, amyloid plaques, neurofibrillary tangles (NFTs), and sustaining neuroinflammation dominate its characteristics. As one of the major tau kinases leading to hyperphosphorylation and aggregation of tau, glycogen synthase kinase-3β (GSK-3β) has been drawing great attention in various AD studies. Another research focus of AD in recent years is the inflammasome, a multiprotein complex acting as a regulator in immunological reactions to exogenous and endogenous danger signals, of which the Nod-like receptor (NLR) family, pyrin domain-containing 3 (NLRP3) inflammasome has been studied mostly in AD and proven to play a significant role in AD development by its activation and downstream effects such as caspase-1 maturation and interleukin (IL)-1β release. Studies have shown that the NLRP3 inflammasome is activated in a GSK-3β-dependent way and that inhibition of the NLRP3 inflammasome downregulates GSK-3β, suggesting that these two important proteins are closely related. This article reviews the respective roles of GSK-3β and the NLRP3 inflammasome in AD as well as their relationship and interaction.

The Akt/glycogen synthase kinase-3β pathway participates in the neuroprotective effect of interleukin-4 against cerebral ischemia/reperfusion injury

Interleukin-4(IL-4) has a protective effect against cerebral ischemia/reperfusion injury. Animal experiments have shown that IL-4 improves the short-and long-term prognosis of neurological function. The Akt(also called protein kinase B, PKB)/glycogen synthase kinase-3β(Akt/GSK-3β) signaling pathway is involved in oxidative stress, the inflammatory response, apoptosis, and autophagy. However, it is not yet clear whether the Akt/GSK-3β pathway participates in the neuroprotective effect of IL-4 against cerebral ischemia/reperfusion injury. In the present study, we established a cerebral ischemia/reperfusion mouse model by middle cerebral artery occlusion for 60 minutes followed by a 24-hour reperfusion. An IL-4/anti-IL-4 complex(10 μg) was intraperitoneally administered 30 minutes before surgery. We found that administration of IL-4 significantly alleviated the neurological deficits, oxidative stress, cell apoptosis, and autophagy and reduced infarct volume of the mice with cerebral ischemia/reperfusion injury 24 hours after reperfusion. Simultaneously, IL-4 activated Akt/GSK-3β signaling pathway. However, an Akt inhibitor LY294002, which was injected at 15 nmol/kg via the tail vein, attenuated the protective effects of IL-4. These findings indicate that IL-4 has a protective effect on cerebral ischemia/reperfusion injury by mitigating oxidative stress, reducing apoptosis, and inhibiting excessive autophagy, and that this mechanism may be related to activation of the Akt/GSK-3β pathway. This animal study was approved by the Animal Ethics Committee of Renmin Hospital of Wuhan University, China(approval No. WDRY2017-K037) on March 9, 2017.

Ischemic postconditioning enhances glycogen synthase kinase-3β expression and alleviates cerebral ischemia/reperfusion injury

The present study established global brain ischemia using the four-vessel occlusion method. Following three rounds of reperfusion for 30 seconds, and occlusion for 10 seconds, followed by reperfusion for 48 hours, infarct area, the number of TUNEL-positive cells and Bcl-2 expression were significantly reduced. However, glycogen synthase kinase-3β activity, cortical Bax and caspase-3 expression significantly increased, similar to results following ischemic postconditioning. Our results indicated that ischemic postconditioning may enhance glycogen synthase kinase-3β activity, a downstream molecule of the phosphatase and tensin homolog deleted on chromosome 10/phosphatidylinositol 3-kinase/protein kinase B signaling pathway, which reduces caspase-3 expression to protect the brain against ischemic injury.

1-methyl-4-phenylpyridinium ion induces endoplasmic reticulum stress through glycogen synthase kinase-3 beta activation in PC12 cells

1-methyl-4-phenylpyridinium ion （MPP^＋） induces endoplasmic reticulum stress and activates caspase-12 in PC12 cells, leading to neuronal apoptosis. However, the underlying molecular mechanism remains unknown. The present study investigated the regulatory effects of nerve growth factor （Akt activator） and lithium chloride （glycogen synthase kinase-3β inhibitor） on the endoplasmic reticulum stress signaling pathway. The results revealed that MPP＋ induced expression of Bip and C/EBP homologous protein. The upregulation of Bip and C/EBP homologous protein, as well as the decreased pro-caspase-12 level induced by MPP^＋ were inhibited by pretreatment of the nerve growth factor or lithium chloride. These results suggest that the phosphatidylinositol 3 kinase-Aktglycogen synthase kinase-3β pathway is involved in MPP-induced endoplasmic reticulum stress.

GSK3/Nrf2调控的生物节律在机体衰老中的规律

背景:生物节律(昼夜节律)紊乱是一个典型的与衰老有关的问题,维持生物节律的正常运作可能是一种很有前景的抗衰老策略。核转录因子NF-E2相关因子2的表达具有生物节律;糖原合成酶激酶3系统代表了一个“调节阀”,它控制核转录因子NF-E2相关因子2水平的细微振荡。抗氧化基因转录水平的昼夜变化可以影响生物体对氧化应激的反应,但是糖原合成酶激酶3/NF-E2相关因子2在调节机体衰老中的具体分子机制仍令人困惑。目的:拟通过对该领域文献的回顾,寻找糖原合成酶激酶3/核转录因子NF-E2相关因子2调控的生物节律在机体衰老中的一般规律。方法:文献资料法通过对有关“糖原合成酶激酶3、核转录因子NF-E2相关因子2、生物节律以及衰老”等相关文献进行检索、查阅和筛选,为全文的分析奠定理论基础。对比分析法通过对所得到文献进行阅读分析,比较文献之间的异同点,为论点提供合理的理论支撑。通过对文献的进一步对比分析,理清相关指标间的关系,为全文的分析明确思路。结果与结论:①糖原合成酶激酶3可通过对节律基因的调节间接调控核转录因子NF-E2相关因子2的表达;②糖原合成酶激酶3和核转录因子NF-E2相关因子2是抗衰老程序的组成部分,且与生物节律相关;③并且糖原合成酶激酶3/核转录因子NF-E2相关因子2参与多种代谢途径,包括与衰老相关疾病(2型糖尿病和癌症)和神经退行性疾病相关的代谢途径。

Human GM3 Synthase Attenuates Taxol-Triggered Apoptosis Associated with Downregulation of Caspase-3 in Ovarian Cancer Cells

Background: Taxol (paclitaxel) inhibits proliferation and induces apoptosis in a variety of cancer cells, but it also upregulates cytoprotective proteins and/or pathways that compromise its therapeutic efficacy. Materials and Method: The roles of GM3 synthase (α2,3-sialyltransferase, ST3Gal V), in attenuating Taxol-induced apoptosis and triggering drug resistance were determined by cloning and overexpressing this enzyme in SKOV3 human ovarian cancer cell line, treating SKOV3 and the transfectants (SKOV3/GS) with Taxol and determining apoptosis, cell survival, clonogenic ability, and caspase-3 activation. Results: In this report, we demonstrated that Taxol treatment resulted in apoptosis which was associated with caspase-3 activation. Taxol treatment upregulated the expression of human GM3 synthase, an enzyme that transfers a sialic acid to lactosylceramide. Moreover, we cloned the full-length GM3 synthase gene and showed for the first time that forced expression of GM3 synthase attenuated Taxol-induced apoptosis and increased resistance to Taxol in SKOV3 cells. Conclusions: GM3 synthase overexpression inhibited Taxol-triggered caspase-3 activation, revealing that upregulation of GM3 synthase prevents apoptosis and hence reduces the efficacy of Taxol therapy.

Protection of INS-1 Cells from Free Fatty Acid-induced Apoptosis by Inhibiting the Glycogen Synthase Kinase-3

To examine the role of glycogen synthase kinase 3 （GSK-3） in the apoptosis of pancreatic β-cells to better understand the pathogenesis and to find new approach to the treatment of type 2 diabetes, apoptosis was induced by oleic acid （OA） in INS-1 cells and the activity of GSK-3 was inhibited by LiCl. The PI staining and flow cytometry were employed for the evaluation of apoptosis. The phosphorylation level of GSK-3 was detected by Western blotting. The results showed that OA at 0.4 mmol/L could cause conspicuous apoptosis of INS- 1 cells and the activity of GSK-3 was significantly increased. After the treatment with 24 mmolFL of LiCl, a inhibitor of GSK-3, the OA-induced apoptosis of INS-1 cells was lessened and the phosphorylation of GSK-3 was increased remarkably. It is concluded that GSK-3 activation plays an important role in OA-induced apoptosis in pancreatic β-cells and inhibition of the GSK-3 activity can effectively protect INS-1 cells from the OA-induced apoptosis. Our study provides a new experimental basis and target for the clinical treatment of type-2 diabetes.

Effects of Nephritis No.3 Recipe on Nitric Oxide,Nitric Oxide Synthase Secreted by Cultured Mesangial Cells in Rats and the Gene Expression of Inducible Nitric Oxide Synthase

Objective:To explore the effect of the Nephritis No. 3 (N-3) recipe on nitric oxide (NO), nitric oxide synthase (NOS) secreted by cultured mesangial cells (MC) and its gene expression of the in-ducible nitric oxide synthase (iNOS). Methods:The drug (nephritis No. 3)-containing serum was prepared with serum pharmacological technique, and then was applied to react on mesangial cells cultured in fetal calf serum (FCS) and cells cultured in FCS plus lipopolysaccharide. To observe the secretion of NO and NOS and the gene expression of iNOS by means of RT-PCR. Results:Under the two kinds of culture conditions, the content of NO and NOS in the groups with drug-containing serum were higher than those without drug-containing serum (P<0. 05, P<0. 01), and the expression of iNOS mRNA was up-regulated too. Conclusion: The N-3 could significantly promote the secretion of NO and NOS and the mRNA expression of iNOS in rats.

Absence of Nitric Oxide Synthase 3 Increases Amyloid <i>β</i>-Protein Pathology in Tg-5xFAD Mice

Aim: The abnormal accumulation, assembly and deposition of the amyloid β-protein (Aβ) are prominent pathological features of patients with Alzheimer’s disease (AD) and related disorders. A number of factors in the brain can influence Aβ accumulation and associated pathologies. The aim of the present study was to determine the consequences of deleting nitric oxide synthase (NOS) 3, the endothelial form of NOS, in Tg-5xFAD mice, a model of parenchymal AD-like amyloid pathology. Methods: Tg-5xFAD mice were bred with NOS3-/- mice. Cohorts of Tg-5xFAD mice and bigenic Tg-5xFAD/NOS3-/- mice were aged to six months followed by collection of the blood and brain tissues from the mice for biochemical and pathological analyses. Results: ELISA analyses show that the absence of NOS3 results in elevated levels of cerebral and plasma Aβ peptides in Tg-5xFAD mice. Immunohistochemical analyses show that the absence of NOS3 increased the amount of parenchymal Aβ deposition and fibrillar amyloid accumulation in Tg-5xFAD mice. The elevated levels of Aβ were not due to changes in the expression levels of transgene encoded human amyloid precursor protein (APP), endogenous β-secretase, or increased proteolytic processing of APP. Conclusions: The results from this study suggest that the loss of NOS3 activity enhances Aβ pathology in Tg-5xFAD mice. These findings are similar to previous studies of NOS2 deletion suggesting that reduced NOS activity and NO levels enhance amyloid-associated pathologies in human APP transgenic mice.

Thymidylate synthase confers pemetrexed resistance of non-small cell lung cancer cells by EGFR/PI3K/AKT pathway

Chemotherapy drug resistance is the main cause leading to the relapse and metastasis of non-small cell lung cancer(NSCLC)patients.Our study aimed to investigate the mechanism of pemetrexed resistance in NSCLC.Firstly,the pemetrexed(PEM)-resistant PC-9 and A549 lung adenocarcinoma cell lines(PC-9/PEM and A549/PEM)were established.The expression of thymidylate synthase(TS)in PC-9/PEM,A549/PEM,A549,and PC-9 cells were analyzed by qRT-PCR and western blot.Then,cell viability,colony formation,migration,and invasion were performed on PEM-resistant cells transfected with TS siRNA.The role of EGFR in PEM resistance of PEM-resistant cells was investigated using EGFR siRNA.The effects of gefitinib and EGFR siRNA on EGFR/PI3K/AKT pathway and downstream signaling Cyclin D1 and E2F1 in PEM-resistant cells were analyzed.Results showed that the protein level of TS was significantly increased in A549/PEM and PC-9/PEM.TS knockdown inhibited the potency of proliferation,colony-forming potential,migration,and invasion in PEM-resistant cells.EGFR knockdown abrogated the resistance to PEM of PEM-resistant cells and suppressed the migration and invasion of PEM-resistant cells.Gefitinib treatment and EGFR knockdown respectively inhibited the EGFR/PI3K/AKT pathway and downregulated Cyclin D1 and E2F1 in PEM-resistant cells.Thus,TS might be a predictive marker for PEM resistance in NSCLC.Inhibition of the EGFR pathway abrogated the resistance to PEM and inhibited the EGFR/PI3K/AKT and downstream signaling of PEM-resistant NSCLC cell lines.

Effect of glycogen synthase kinase 3β on treatment of corticosterone-induced depression in mice treated with Xiaobuxintang-2

Objective:Xiaobuxintang-2(XBXT-2)has antidepressant effects,but the underlying mechanism is still unclear.In this study,we used the corticosterone-induced depression mouse model to study the antidepressant effect of XBXT-2and its underlying mechanisms.Methods:A mouse model of depression was induced by corticosterone.The mice were divided into 5 groups:(i)control group,(ii)corticosterone group(CORT),(iii)corticosterone+XBXT-2(CORT+XBXT-2)group,(iv)corticosterone+XBXT-2+lentiviral empty group(CORT+XBXT-2+no-load),(v)corticosterone+XBXT-2+lentivirus GSK3βOverexpression group(CORT+XBXT-2+GSK3β).The expression level of GSK3βin the hippocampus was detected by immunoblotting,and the depression status of the mice was evaluated by forced swimming test and tail suspension test.Results:The GSK3βlentivirus induced the high expression of GSK3βin the hippocampus of mice,and the mRNA and protein levels were significantly increased compared with the control group.The immobility time is significantly increased in corticosterone injection-induced depression model mice(CORT group),and XBXT-2 can effectively reduce the immobility time of depression model mice.Overexpression of GFP empty lentivirus did not affect mouse behavior,whereas overexpression of GSK3βsignificantly increased immobility time in depression model mice according to forced swimming and tail suspension experiments.Conclusion:High expression of GSK3βin the hippocampus of mice can inhibit the therapeutic effect of XBXT-2 on the corticosterone-induced depression in mice.

Porcine Placenta Extract Enhances Ceramide Synthase 3 Expression through the PPARδ/ILK/Akt/mTOR/STAT3 Pathway

Porcine placenta extract (PPE) is widely accepted as an ingredient in complementary and alternative medicine and previous studies have reported its availability, however, its underlying action mechanism remains unclear. In this study, we investigated the underlying mechanism of PPE-induced ceramide synthase 3 upregulation. PPE enhanced the expression of ceramide synthase 3 at both the mRNA and protein levels in HaCaT cells. Moreover, PPE-induced ceramide synthase3 upregulation was suppressed by the Akt inhibitor, suggesting the involvement of Akt in the underlying mechanism. As the PI3K inhibitor did not affect PPE-induced ceramide synthase 3 upregulation, the factors upstream of Akt were estimated. Inhibition and small interfering RNA experiments demonstrated that the peroxisome proliferator-activated receptors δ (PPARδ) and integrin-linked kinase (ILK) are involved in the phosphorylation of Akt. Next, we explored the factors downstream of Akt and found that PPE induced phosphorylation of the STAT3 while PPE-induced upregulation of ceramide synthase 3 was significantly suppressed by the inhibitor of the mTOR, suggesting that the mTOR/STAT3 pathway is involved in the downstream of Akt. These results demonstrate that PPE upregulates CerS3 expression via the PPARδ/ILK/Akt/mTOR/STAT3 pathway.

Regenerative potential of targeting glycogen synthase kinase-3 signaling in neural tissues

Multiple roles of glycogen synthase kinase-3（GSK-3）in neural tissues：GSK-3 is a serine/threonine kinase that has two isoforms encoded by two different genes,GSK-3αand GSK-3β,in mammals.GSK-3 has several sites of serine and tyrosine phosphorylation.

Molecular docking study of xylogranatins binding to glycogen synthase kinase-3β

Objective The mangrove tree Xylocarpus granatum J.Koenig(X.granatum)is a medicinal plant used to treat various diseases in several Asian countries.Many bioactive natural products have been isolated from the plants,particularly several groups of limonoids,including 18 xylogranatins(Xyl-A to R),all of which bear a furyl-δ-lactone core commonly found in limonoids.Based on a structural analogy with the limonoids obacunone and gedunin,we hypothesized that xylogranatins could target the enzyme glycogen synthase kinase-3β(GSK-3β),a major target for the treatment of neurodegenerative pathologies,viral infections,and cancers.Methods We investigated the binding of the 18 xylogranatins to GSK-3βusing molecular docking in comparison with two known reference GSK-3βATP-competitive inhibitors,LY2090314 and AR-A014418.For each compound bound to GSK-3β,the empirical energy of interaction(ΔE)was calculated and compared to that obtained with known GSK-3βinhibitors and limonoid triterpenes that target this enzyme.Results Five compounds were identified as potential GSK-3βbinders,Xyl-A,-C,-J,-N,and-O,for which the calculated empiricalΔE was equivalent to that calculated using the best reference molecule AR-A014418.The best ligand is Xyl-C,which is known to have marked anticancer properties.Binding of Xyl-C to the ATP-binding pocket of GSK-3βpositions the furyl-δ-lactone unit deep into the binding-site cavity.Other xylogranatin derivatives bearing a central pyridine ring or a compact polycyclic structure are much less adapted for GSK-3βbinding.Structure-binding relationships are discussed.Conclusion GSK-3βmay contribute to the anticancer effects of X.granatum extract.This study paves the way for the identification of other furyl-δ-lactone-containing limonoids as GSK-3βmodulators.