Prenylated Flavanone Isolated from Dalea Species as a Potential Multitarget-Neuroprotector in an In Vitro Alzheimer's Disease Mice Model

Alzheimer's disease (AD) involves a neurodegenerative process that has not yet been prevented, reversed, or stopped. Continuing with the search for natural pharmacological treatments, flavonoids are a family of compounds with proven neuroprotective effects and multi-targeting behavior. The American genus Dalea L. (Fabaceae) is an important source of bioactive flavonoids. In this opportunity, we tested the neuroprotective potential of three prenylated flavanones isolated from Dalea species in a new in vitro pre-clinical AD model previously developed by us. Our approach consisted in exposing neural cells to conditioned media (3xTg-AD ACM) from neurotoxic astrocytes derived from hippocampi and cortices of old 3xTg-AD mice, mimicking a local neurodegenerative microenvironment. Flavanone 1 and 3 showed a neuroprotective effect against 3xTg-AD ACM, being 1 more active than 3. The structural requirements to afford neuroprotective activity in this model are a 5'-dimethylallyl and 4'-hydroxy at the B ring. In order to search the mechanistic performance of the most active flavanone, we focus on the flavonoid-mediated regulation of GSK-3β-mediated tau phosphorylation previously reported. Flavanone 1 treatment decreased the rise of hyperphosphorylated tau protein neuronal levels induced after 3xTg-AD ACM exposure and inhibited the activity of GSK-3β. Finally, direct exposure of these neurotoxic 3xTg-AD astrocytes to flavanone 1 resulted in toxicity to these cells and reduced the neurotoxicity of 3xTg-AD ACM as well. Our results allow us to present compound 1 as a natural prenylated flavanone that could be used as a precursor to development and design of future drug therapies for AD.

Glutaredoxin 2 protects lens epithelial cells from epithelial-mesenchymal transition by suppressing mitochondrial oxidative stress-related upregulation of integrin-linked kinase

Glutaredoxin 2 (Grx2), a mitochondrial glutathione-dependent oxidoreductase, is crucial for maintaining redox homeostasis and cellular functions in the lens. The oxidative stress-induced epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is related to posterior capsule opacification. In this study, we investigated the effects of Grx2 on oxidative stress-induced EMT in LECs during posterior capsule opacification. We found that Grx2 expression was substantially decreased during the EMT of LECs and in a mouse model of cataract surgery. Deletion of Grx2 aggravated the generation of reactive oxygen species, including those that are mitochondria-derived, and promoted the proliferation and EMT of the LECs. This was reversed by Grx2 overexpression. In vivo, proteomic liquid chromatography-mass spectrometry analysis showed that integrin-linked kinase (ILK) was significantly upregulated in the lens posterior capsule of a Grx2 knockout (KO) mouse model. Compared with that of the wild-type group, the expression of ILK and EMT markers was increased in the Grx2 KO group which was reversed in the Grx2 knock-in group. Inhibition of ILK partially blocked Grx2 knockdown-induced EMT and prevented the increased phosphorylation of Akt and GSK-3β and the nuclear translocation of β-catenin in the Grx2 KO group. Finally, inhibition of the Wnt/β-catenin pathway partially blocked the Grx2 knockdown-induced EMT. In conclusion, we demonstrated that Grx2 protects LECs from oxidative stress-related EMT by regulating the ILK/Akt/GSK-3β axis.

Ketamine modulates neural stem cell differentiation by regulating TRPC3 expression through the GSK3β/β-catenin pathway

Ketamine, a popular anesthetic, is often abused by people for its hallucinogenic effect. Thus, the safety of ketamine in pediatric populations has been called into question for potential neurotoxic effects. However, ketamine also has neuroprotective effects in many brain injury models. The differentiation of neural stem cells (NSCs) was influenced significantly by ketamine, but the molecular mechanism is still unclear. NSCs were extracted from the hippocampi of postnatal day 1 rats and treated with ketamine to induce NSCs differentiation. Our results found that ketamine promoted neuronal differentiation of NSCs dose-dependently in a small dose range (P < 0.001). The main types of neurons from NSCs were cholinergic (51 ± 4 %; 95 % CI: 41-61 %) and glutamatergic neurons (34 ± 3 %; 95 % CI: 27-42 %). Furthermore, we performed RNA sequencing to promise a more comprehensive understanding of the molecules regulated by ketamine. Finally, we combined bioimaging and multiple molecular biology techniques to clarify that ketamine influences NSC differentiation by regulating transient receptor potential canonical 3 (TRPC3) expressions. Ketamine dramatically repressed TRPC3 expression (MD [95 % CI]=0.67 [0.40-0.95], P < 0.001) with a significant increase of phosphorylated glycogen synthase kinase 3β (p-GSK3β; MD [95 % CI]=1.00 [0.74-1.27], P < 0.001) and a decrease of β-catenin protein expression (MD [95 % CI]=0.60 [0.32-0.89], P = 0.001), thereby promoting the differentiation of NSCs into neurons and inhibiting their differentiation into astrocytes. These results suggest that TRPC3 is necessary for ketamine to modulate NSC differentiation, which occurs partly via regulation of the GSK3β/β-catenin pathway.

Sacubitril/valsartan attenuates myocardial ischemia/reperfusion injury via inhibition of the GSK3β/NF-κB pathway in cardiomyocytes

In ischemia/reperfusion (I/R) injury, both inflammation and apoptosis play a vital role, and the inhibition of excessive inflammation and apoptosis show substantial clinical potential in the treatment of I/R disease. The role of sacubitril/valsartan (SAC/VAL)-a first-in-class angiotensin receptor-neprilysin inhibitor (ARNI)-in inflammation regulation and apoptosis in the context of I/R injury needs to be further explored. In this study, we investigate the short- and long-term effects of SAC/VAL administration in treating adult murine I/R injury both in vivo and in vitro. Our results verified that the application of SAC/VAL could reduce infarct size and suppress apoptosis and the inflammatory response in the acute phase post I/R. Long-term application of SAC/VAL for four weeks significantly improved ventricular function and reversed pathological ventricular remodeling. Mechanistically, SAC/VAL treatment induces the inhibition of the GSK3β-mediated NF-κB pathway through synergistically blocking angiotensin 1 receptor (AT1R) and activating natriuretic peptide receptor (NPR). In summary, we reported the therapeutic role of SAC/VAL in regulating the GSK3β/NF-κB signaling pathway to suppress the inflammatory response and apoptosis, thereby reducing cardiac dysfunction and remodeling post I/R.

PLK2 targets GSK3β to protect against cisplatin-induced acute kidney injury

Cisplatin-induced acute kidney injury (AKI), which is accompanied by a rapid decline in renal function and a high risk of death, is a complex critical illness with no effective or specific treatment. Polo-like kinase 2 (PLK2), a serine/threonine kinase, is involved in the progression of multiple diseases, including cancers, cardiac fibrosis, diabetic nephropathy, etc. Here, by integrating two Gene Expression Omnibus (GEO) datasets of cisplatin-induced AKI animal models, we identified PLK2 as a significantly up-regulated gene in AKI renal tissues, which was then verified in different AKI animal models and cell models. Suppressing PLK2 using siRNAs or inhibitors could enhance cisplatin-induced AKI by inducing severe apoptosis and oxidative stress damage, while enforced PLK2 expression could prevent renal dysfunction induced by cisplatin. We further discovered that PLK2 might phosphorylate glycogen synthase kinase 3β (GSK3β) in the pathogenesis of AKI. In conclusion, our results show that PLK2 play a protective role in cisplatin-induced AKI and may be a new protective target of cisplatin nephrotoxicity.

Modification of mesenchymal stem cells by HMGB1 promotes the activity of Cav3.2 T-type calcium channel via PKA/β-catenin/γ-cystathionase pathway

Background

Mesenchymal stem cells (MSC) hold great promise for treating cardiovascular disease. Recently, we genetically modified MSCs with high mobility group box 1 (HMGB1), and these cells demonstrated high mobility by efficient migrating and homing to target neointima. The possible mechanism was investigated in the current study.

Methods

Rat MSCs were transfected with lentivirus containing HMGB1 cDNA to yield MSC-H cell line stably overexpressing HMGB1. The MSC-C cells which were transfected with empty lentivirus served as negative control, and the differentially expressed genes were analyzed by microarray. The cell mobility was determined by transwell migration assay. Intracellular free calcium and the expression of Cav3.2 T-type calcium channel (CACNA1H) were assayed to analyze activity of CACNA1H-mediated calcium influx. H₂S production and γ-cystathionase expression were examined to assess the activity of γ-cystathionase/H₂S signaling. The interaction of HMGB1 with γ-cystathionase in MSC-H cells was analyzed by co-immunoprecipitation. Luciferase reporter assay was performed to determine whether the promoter activity of γ-cystathionase was regulated by interaction of β-catenin and TCF/LEF binding site. Intercellular cAMP, PKA activity, phosphorylation of β-catenin, and GSK3β were investigated to reveal cAMP/PKA mediated β-catenin activation.

Result

Microarray analysis revealed that differentially expressed genes were enriched in cAMP signaling and calcium signaling. CACNA1H was upregulated to increase intracellular free calcium and MSC-H cell migration. Blockage of CACNA1H by ABT-639 significantly reduced intracellular free calcium and cell migration. The γ-cystathionase/H₂S signaling was responsible for CACNA1H activation. H₂S production was increased with high expression of γ-cystathionase in MSC-H cells, which was blocked by γ-cystathionase inhibitor DL-propargylglycine. Upregulation of γ-cystathionase was not attributed to interaction with HMGB1 overexpressed in MSC-H cells although γ-cystathionase was suggested to co-immunoprecipitate with oxidized HMGB1. Bioinformatics analysis identified a conserved TCF/LEF binding site in the promoter of γ-cystathionase gene. Luciferase reporter assay confirmed that the promoter had positive response to β-catenin which was activated in MSC-H cells. Finally, cAMP/PKA was activated to phosphorylate β-catenin at Ser657 and GSK3β, enabling persisting activation of Wnt/β-catenin signaling in MSC-H cells.

Conclusion

Our study revealed that modification of MSCs with HMGB1 promoted CACNA1H-mediated calcium influx via PKA/β-catenin/γ-cystathionase pathway. This was a plausible mechanism for high mobility of MSC-H cell line.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02677-z.

Sex Differences and Estradiol Effects in MAPK and Akt Cell Signaling across Subregions of the Hippocampus

INTRODUCTION

Rapid effects of estrogens within the hippocampus of rodents are dependent upon cell-signaling cascades, and activation of these cascades by estrogens varies by sex. Whether these pathways are rapidly activated within the dentate gyrus (DG) and CA1 by estrogens across sex and the anatomical longitudinal axis has been overlooked.

METHODS

Gonadally intact female and male rats were given either vehicle or physiological systemic low (1.1 µg/kg) or high (37.3 µg/kg) doses of 17β-estradiol 30 min prior to tissue collection. To control for the effects of circulating estrogens, an additional group of female rats was ovariectomized (OVX) and administered 17β-estradiol. Brains were extracted, and tissue punches of the CA1 and DG were taken along the longitudinal hippocampal axis (dorsal and ventral) and analyzed for key mitogen-activated protein kinase (MAPK) and protein kinase B (Akt) cascade phosphoproteins.

RESULTS

Intact females had higher Akt pathway phosphoproteins (pAkt, pGSK-3β, and pp70S6K) than males in the DG (dorsal and ventral) and lower pERK1/2 in the dorsal DG. Most effects of 17β-estradiol on cell signaling occurred in OVX animals. In OVX animals, 17β-estradiol increased cell signaling of MAPK and Akt phosphoproteins (pERK1/2, pJNK, pAkt, and pGSK-3β) in the CA1 and pERK1/2 and pJNK DG.

DISCUSSION/CONCLUSIONS

Systemic 17β-estradiol treatment rapidly alters phosphoprotein levels in the hippocampus, dependent on reproductive status, and intact females have greater expression of Akt phosphoproteins than that in intact males in the DG. These findings shed light on underlying mechanisms of sex differences in hippocampal function and response to interventions that affect MAPK or Akt signaling.

GSK3-beta as a candidate therapeutic target in soft tissue sarcomas

Soft tissue sarcoma (STS) is a predominantly fatal rare malignancy with inadequate treatment options. Glycogen synthase kinase 3β (GSK-3β) is an emerging target in human malignancies. Its therapeutic relevance in STS is unknown. We analyzed the prognostic impact of GSK-3β gene and protein expression in two independent cohorts of patients with STS. We then treated STS cell lines and mice xenografts with a novel GSK-3 inhibitor 9-ING-41 alone or in combination with chemotherapy. We demonstrated that 9-ING-41 treatment induced significant STS cells apoptosis and was synergistic in vivo when combined with chemotherapy. Mechanistically, 9-ING-41 induces significant apoptosis of STS cells via suppression of NF-κB-mediated X-linked inhibitor of apoptosis protein (XIAP) expression. These data support the inclusion of patients with STS in clinical studies of 9-ING-41 alone and in combination with chemotherapy.

The GSK-3β/β-Catenin Signaling-Mediated Brain-Derived Neurotrophic Factor Pathway Is Involved in Aluminum-Induced Impairment of Hippocampal LTP In Vivo

The neurotoxic effects of aluminum (Al) are associated with the impairment of synaptic plasticity, the biological basis of learning and memory, the major form of which is long-term potentiation (LTP). The canonical glycogen synthase kinase-3β (GSK-3β)/β-catenin signaling-mediated brain-derived neurotrophic factor (BDNF) pathway has been suggested to play important roles in memory. Thus, Al may affect LTP through this pathway. In this study, a Sprague-Dawley rat model of neurotoxicity was established through intracerebroventricular (i.c.v.) injection of aluminum maltol (Al(mal)₃), which was achieved by preimplantation of a cannula into the lateral ventricle. The rats in the control and Al-treated groups received a daily injection of SB216763, an inhibitor of GSK-3β. Electrophysiology and western blot analysis were used to investigate the regulatory effect of the GSK-3β/β-catenin signaling-mediated BDNF pathway on LTP impairment induced by Al(mal)₃. The results confirmed that i.c.v. injection of Al(mal)₃ significantly suppressed the field excitatory postsynaptic potential (fEPSP) amplitude, as indicated by a decrease in BDNF protein expression, which was accompanied by dose-dependent decreases in β-catenin protein expression and the phosphorylation of GSK-3β at Ser9. Rats that received SB216763, a GSK-3β inhibitor, exhibited higher fEPSP amplitudes than control rats. Furthermore, SB216763 treatment upregulated the hippocampal protein expression of BDNF and β-catenin while increasing the ratio of p-GSK-3β/GSK-3β. From the perspective of the identified β-catenin-BDNF axis, Al impairs hippocampal LTP, possibly through the GSK-3β/β-catenin signaling-mediated BDNF pathway.

Discovery of thiazolidin-4-one analogue as selective GSK-3β inhibitor through structure based virtual screening

GSK-3β directly phosphorylate tubulin binding site of tau protein, indicating its importance in tau aggregation and, therefore, in Alzheimer's disease pathology. New GSK-3β inhibitors were identified using a structure-based screening, ADMET analysis. These studies revealed that ZINC09036109, ZINC72371723, ZINC72371725, and ZINC01373165 approached optimal ADMET properties along with good MM-GBSA dG binding. Protein kinase assays of these compounds against eight disease-relevant kinases were performed. During disease-relevant kinase profiling, ZINC09036109 ((E)-2-((3,4-dimethylphenyl)imino)-5-(3-methoxy-4-(naphthalen-2-ylmethoxy)benzyl)thiazolidin-4-one) emerged as a selective GSK-3β inhibitor with more than 10-fold selectivity over other disease-relevant kinases. Molecular dynamics study of ZINC09036109 molecule revealed interactions with Ile62, Phe67, Val135, Leu188, Asp200 amino acid residues of the binding site of GSK-3β, which were highly comparable to the co-crystallized molecule and hence validating comparative better activity of this compound compared to overall screened molecules.

Protective effect of GSK-3β/Nrf2 mediated by dimethyl fumarate in middle cerebral artery embolization reperfusion rat model

AIM

This study investigated the protective effect of dimethyl fumarate (DMF) in rats by mediating GSK3-β/Nrf2 using the middle cerebral artery embolization reperfusion (MCAO/R) rat model.

BACKGROUND

After an acute ischemic stroke (AIS), oxidative stress occurs. Dimethyl fumarate (DMF), a nuclear factor-E2-related factor 2 (Nrf2) activator, approved by the US Food and Drug Administration (FDA), was observed to regulate the Nrf2 pathway by acting as an anti-oxidative stress agent; however, whether this agent is involved in inhibiting GSK-3β remains to be established.

METHODS

DMF model was used to explore the effects of GSK-3β on Nrf2 expression level, Nrf2-ARE binding activity and Nrf2/ARE downstream expression level of anti-oxidant stress protein in Cerebral ischemia-reperfusion injury (CIRI). 60 rats were randomly divided into Sham group, MCAO/R group, solvent control group (DMSO group) and DMF treatment group, with 15 rats in each group. The MCAO/R, DMSO and DMF groups were considered in the MCAO/R model using the modified thread embolization method. In contrast, the Sham group was only anaesthetized and disinfected, and tissue muscle was dissected without inserting suture emboli. DMF group was gavaged with 45mg/kg per day of DMF, DMSO control group was gavaged with DMSO of equal volume, while MCAO/R group was only modeled without any intragastric treatment. The rats were treated seven days after the operation, and a neurological function Longa score was estimated. The rats were sacrificed seven days later, and the infarct volume was assessed by TTC staining. Hematoxylin-eosin (HE) staining was used to observe the pathological changes in rat brain tissue. Nissl staining was used to observe the expression of neurons in the infarcted cortex. Western blotting (WB) was used to observe the protein expression levels of glycogen synthase kinase 3β(GSK-3β), nuclear factor E2-related factor 2 (Nrf2), downstream heme oxygenase 1 (HO1) and NADPH quinone oxidoreductase 1 (NQO1) in four groups. The expression levels of GSK-3β and Nrf2 in the four groups were observed by immunohistochemistry and immunofluorescence.

RESULTS

(1) The Longa score of the MCAO/R, DMSO and DMF groups was found to be higher compared to the Sham group, indicating successful operation. The Longa score of the DMF group was lower than that of the other three groups 4-7 days after surgery (P<0.05). (2) HE and Nissl staining showed that the DMF group had lower neuron necrosis and higher gliosis compared to the control groups. (3) TTC staining results showed that the infarct volume of the DMF group was significantly smaller than the MCAO/R and DMSO groups. (4) Protein results showed that the GSK-3β expression in the DMF group was lower than that in all groups, while the expression of Nrf2, HO1 and NQO1 was higher compared to other groups.

CONCLUSION

DMF can reduce neurological deficits and infarct size in the MCAO/R model. The protective effect may be related to decreased GSK-3β expression and increased Nrf2 expression, which may play a role in anti-oxidative stress.

Glycogen synthase kinase 3β promotes osteosarcoma invasion and migration via regulating PTEN and phosphorylation of focal adhesion kinase

Aim: Typical features of human osteosarcoma are highly invasive and migratory capacities. Our study aimed to investigate the roles of glycogen synthase kinase 3β (GSK3β) in human osteosarcoma metastasis.

Methods: GSK3β expressions in clinical osteosarcoma tissues with or without metastasis were examined by immunohistochemical staining. The expressions of GSK3β, p-GSK3β^Ser9, and p-GSK3β^Tyr216 in human osteoblast cells (hFOB1.19) and human osteosarcoma cells (MG63, SaOS-2, and U2-OS) were detected by Western blotting. The GSK3β activity was measured by non-radio isotopic in vitro kinase assay. Migration and invasion abilities of MG-63 cells treated with small-molecular GSK3β inhibitors were respectively examined by monolayer-based wound-healing assay and transwell assay. The mRNA expressions of GSK3β, matrix metalloproteinase-2 (MMP-2), MMP-9, phosphatase with tensin homology (PTEN), and focal adhesion kinase (FAK) were detected after siRNA transfection for 72 h. Meanwhile, protein expressions of GSK3β, FAK, p-FAK^Y397, PTEN, MMP-2, and MMP-9 were measured by Western blotting.

Results: Clinical osteosarcoma tissues with metastasis showed higher GSK3β expressions. MG63 and U2-OS cells that were easy to occur metastasis showed significantly higher expressions and activities of GSK3β than SaOS-2 cells. Inhibition of GSK3β with small-molecular GSK3β inhibitors in MG63 cells significantly attenuated cell migration and invasion. These effects were associated with reduced expressions of MMP-2 and MMP-9. Moreover, increased PTEN and decreased p-FAK^Y397 expressions were observed following GSK3β knockdown by siRNA transfection. Conclusion: GSK3β might promote osteosarcoma invasion and migration via pathways associated with PTEN and phosphorylation of FAK.

Downregulation of GSK-3β Expression via Ultrasound-Targeted Microbubble Destruction Enhances Atherosclerotic Plaque Stability in New Zealand Rabbits

Accumulating evidence suggests that atherosclerosis (AS) is the underlying cause of vascular diseases, including heart disease and stroke. Ultrasound-targeted microbubble destruction (UTMD) technology provides a tolerable, efficient and effective system for drug delivery and gene transfection, which has broad application prospects in the treatment of AS. In addition, glycogen synthase kinase (GSK)-3β has been implicated as a potentially valuable therapeutic agent for AS treatment; however, the specific molecular mechanisms remain unknown. Therefore, this study was conducted to explore the effect of downregulation of GSK-3β expression via UTMD on atherosclerotic plaque stability. We established a THP-1 macrophage-derived foam cell model in vitro and an atherosclerotic plaque model in the right common carotid artery of New Zealand rabbits. We determined levels of the relevant vulnerable plaque stability elements. The results indicate that GSK-3β was upregulated in the foam cells and in atherosclerotic rabbits. Downregulation of GSK-3β expression by UTMD suppressed vulnerable plaque factors and inflammation in vitro and in vivo, changed the cytoskeleton of the foam cells in vitro, increased Young's modulus and decreased the peak intensity of atherosclerotic plaque in vivo. Moreover, GSK-3β inhibition by UTMD did not influence the viability of the foam cells. Collectively, our results indicate that GSK-3β could be a potential target for anti-atherogenic interventions and, in particular, can improve the stability of AS plaques in combination with UTMD.

Identification and Mechanistic Characterization of a Peptide Inhibitor of Glycogen Synthase Kinase (GSK3β) Derived from the Disrupted in Schizophrenia 1 (DISC1) Protein

Glycogen synthase kinase 3-beta (GSK3β) is a critical regulator of several cellular pathways involved in neurodevelopment and neuroplasticity and as such is a potential focus for the discovery of new neurotherapeutics toward the treatment of neuropsychiatric and neurodegenerative diseases. The majority of efforts to develop inhibitors of GSK3β have been focused on developing small molecule inhibitors that compete with adenosine triphosphate (ATP) through direct interaction with the ATP binding site. This strategy has presented selectivity challenges due to the evolutionary conservation of this domain within the kinome. The disrupted in schizophrenia 1 (DISC1) protein has previously been shown to bind and inhibit GSK3β activity. Here, we report the characterization of a 44-mer peptide derived from human DISC1 (hDISCtide) that is sufficient to both bind and inhibit GSK3β in a noncompetitive mode distinct from classical ATP competitive inhibitors. Based on multiple independent biochemical and biophysical assays, we propose that hDISCtide interacts at two distinct regions of GSK3β: an inhibitory region that partially overlaps with the binding site of FRATide, a well-known GSK3β binding peptide, and a specific binding region that is unique to hDISCtide. Taken together, our findings present a novel avenue for developing a peptide-based selective inhibitor of GSK3β.

Unleashing β-catenin with a new anti-Alzheimer drug for bone tissue regeneration

The Wnt/β-catenin signaling pathway is critical for bone differentiation and regeneration. Tideglusib, a selective FDA approved glycogen synthase kinase-3β (GSK-3β) inhibitor, has been shown to promote dentine formation, but its effect on bone has not been examined. Our objective was to study the effect of localized Tideglusib administration on bone repair. Bone healing between Tideglusib treated and control mice was analysed at 7, 14 and 28 days postoperative (PO) with microCT, dynamic histomorphometry and immunohistology. There was a local downregulation of GSK-3β in Tideglusib animals, resulting in a significant increase in the amount of new bone formation with both enhanced cortical bone bridging and medullary bone deposition. The bone formation in the Tideglusib group was characterized by early osteoblast differentiation with down-regulation of GSK-3β at day 7 and 14, and higher accumulation of active β-catenin at day 14. Here, for the first time, we show a positive effect of Tideglusib on bone formation through the inactivation of GSK-3β. Furthermore, the findings suggest that Tideglusib does not interfere with precursor cell recruitment and commitment, contrary to other GSK-3β antagonists such as lithium chloride. Taken together, the results indicate that Tideglusib could be used directly at a fracture site during the initial intraoperative internal fixation without the need for further surgery, injection or drug delivery system. This FDA-approved drug may be useful in the future for the prevention of non-union in patients presenting with a high risk for fracture-healing.

Alleviation of brain injury by applying TGN-020 in the supraoptic nucleus via inhibiting vasopressin neurons in rats of focal ischemic stroke

AIMS

To understand mechanisms underlying vasopressin hypersecretion in stroke and its association with brain injury, we investigated effects of blocking aquaporin 4 (AQP4) in the supraoptic nucleus (SON) on vasopressin neuronal activity and cerebral injuries in male rats of unilateral middle cerebral artery occlusion (MCAO).

MAIN METHODS

Establishing MCAO model without or with microinjection of TGN-020 into the SON, performing Western blots and immunohistochemistry and analyzing the expression levels and spatial distribution of functional proteins in the SON and/or the cerebral cortex.

KEY FINDINGS

MCAO increased plasma vasopressin levels, caused neurological damage and increased glycogen synthase kinase 3β (GSK-3β) in the SON and the cortex of MCAO side. In the SON, MCAO significantly increased c-Fos in vasopressin neurons and astrocytic somata in the ventral glial lamina. MCAO significantly reduced glial fibrillary acidic protein (GFAP) and AQP4 around vasopressin neurons, which accompanied separation of GFAP from AQP4. By contrast, blocking AQP4 by microinjection of TGN-020 into the SON blocked MCAO-evoked GSK-3β increase as well as the reduction of AQP4 relative to GFAP around vasopressin neurons in the SON. In the cortex, TGN-020 in the SON also blocked MCAO-evoked increase in GSK-3β while reduced neurological damages.

SIGNIFICANCE

These findings indicate that MCAO disrupts interactions of GFAP with AQP4 in astrocytic processes in the SON, which increases vasopressin neuronal activity. Blocking AQP4 in the SON can block abnormal activation of vasopressin neurons and alleviate ischemic brain injury, which provides novel targets for alleviating ischemic brain injury.

PROTACs suppression of GSK-3β, a crucial kinase in neurodegenerative diseases

Glycogen synthase kinase 3β (GSK-3β) is involved in a variety of diseases such as neurodegenerative diseases, bipolar disorder, and diabetes. In this study, a series of heterobifunctional small molecule proteolysis targeting chimera (PROTAC) were designed and synthesized based on E3 ubiquitin ligase cereblon (CRBN). Most of PROTACs displayed good inhibitory activity, with the IC₅₀ values at the double-digits nanomolar levels and moderate protein degradation ability against GSK-3β. Western-blot data showed compound PG21 can effectively degrade GSK-3β in a dose-dependent manner, which can induce 44.2% protein degradation at 2.8 μM. Further pharmacological experiments revealed that the ability of PG21 to degrade GSK-3β is mediated by the ubiquitin-proteasome system (UPS). In addition, PG21 protects against glutamate-induced cell death in HT-22 cells. As the first PROTAC example to degrade GSK-3β protein, the present study has provided potential candidates for further investigation in the biological function of GSK-3β protein and its association with diseases.

Wnt modulation in bone healing

Genetic studies have been instrumental in the field of orthopaedics for finding tools to improve the standard management of fractures and delayed unions. The Wnt signaling pathway that is crucial for development and maintenance of many organs also has a very promising pathway for enhancement of bone regeneration. The Wnt pathway has been shown to have a direct effect on stem cells during bone regeneration, making Wnt a potential target to stimulate bone repair after trauma. A more complete view of how Wnt influences animal bone regeneration has slowly come to light. This review article provides an overview of studies done investigating the modulation of the canonical Wnt pathway in animal bone regeneration models. This not only includes a summary of the recent work done elucidating the roles of Wnt and β-catenin in fracture healing, but also the results of thirty transgenic studies, and thirty-eight pharmacological studies. Finally, we discuss the discontinuation of sclerostin clinical trials, ongoing clinical trials with lithium, the results of Dkk antibody clinical trials, the shift into combination therapies and the future opportunities to enhance bone repair and regeneration through the modulation of the Wnt signaling pathway.

Glycogen synthase kinase 3 β activity is essential for Polo-like kinase 2- and Leucine-rich repeat kinase 2-mediated regulation of α-synuclein

Parkinson's disease (PD) is a currently incurable disease and the number of patients is expected to increase due to the extended human lifespan. α-Synuclein is a pathological hallmark of PD and variations and triplications of the gene encoding α-synuclein are strongly correlated with the risk of developing PD. Decreasing α-synuclein is therefore a promising therapeutic strategy for the treatment of PD. We have previously demonstrated that Polo-like kinase 2 (PLK-2) regulates α-synuclein protein levels by modulating the expression of α-synuclein mRNA. In this study, we further expand the knowledge on this pathway and show that it depends on down-stream modulation of Glycogen-synthase kinase 3 β (GSK-3β). We show that PLK-2 inhibition only increases α-synuclein levels in the presence of active GSK-3β in both cell lines and primary neuronal cultures. Furthermore, direct inhibition of GSK-3β decreases α-synuclein protein and mRNA levels in our cell model and overexpression of Leucine-rich repeat kinase 2, known to activate GSK-3β, increases α-synuclein levels. Finally, we show an increase in endogenous α-synuclein in primary neurons when increasing GSK-3β activity. Our findings demonstrate a not previously described role of endogenous GSK-3β activity in the PLK-2 mediated regulation of α-synuclein levels. This finding opens up the possibility of GSK-3β as a novel target for decreasing α-synuclein levels by the use of small molecule compounds, hereby serving as a disease modulating strategy.

Differentiation-inducing factor-1 prevents hepatic stellate cell activation through inhibiting GSK3β inactivation

Differentiation-inducing factor-1 (DIF-1), a morphogen produced by the cellular slime mold Dictyostelium discoideum, is a natural product that has attracted considerable attention for its antitumor properties. Here, we report a novel inhibitory effect of DIF-1 on the activation of hepatic stellate cells (HSCs) responsible for liver fibrosis. DIF-1 drastically inhibited transdifferentiation of quiescent HSCs into myofibroblastic activated HSCs in a concentration-dependent manner, thus conferring an antifibrotic effect against in the liver. Neither SQ22536, an adenylate cyclase inhibitor, nor ODQ, a guanylate cyclase inhibitor, showed any effect on the inhibition of HSC activation by DIF-1. In contrast, TWS119, a glycogen synthase kinase 3β (GSK3β) inhibitor, attenuated the inhibitory effect of DIF-1. Moreover, the level of inactive GSK3β (phosphorylated at Ser9) was significantly reduced by DIF-1. DIF-1 also inhibited nuclear translocation of β-catenin and reduced the level of non-phospho (active) β-catenin. These results suggest that DIF-1 inhibits HSC activation by disrupting the Wnt/β-catenin signaling pathway through dephosphorylation of GSK3β. We propose that DIF-1 is a possible candidate as a therapeutic agent for preventing liver fibrosis.

PBX homeobox 1 enhances hair follicle mesenchymal stem cell proliferation and reprogramming through activation of the AKT/glycogen synthase kinase signaling pathway and suppression of apoptosis

BACKGROUND

PBX homeobox 1 (PBX1) is involved in the maintenance of the pluripotency of human embryonic and hematopoietic stem cells; however, the effects of PBX1 in the self-renewal and reprogramming of hair follicle mesenchymal stem cells (HF-MSCs) are unclear. The AKT/glycogen synthase kinase (GSK) 3β pathway regulates cell metabolism, proliferation, apoptosis, and reprogramming, and p16 and p21, which act downstream of this pathway, regulate cell proliferation, cell cycle, and apoptosis induced by reprogramming. Here, we aimed to elucidate the roles of PBX1 in regulating the proliferation and reprogramming of HF-MSCs.

METHODS

A lentiviral vector designed to carry the PBX1 sequence or PBX1 short hairpin RNA sequence was used to overexpress or knock down PBX1. The roles of PBX1 in proliferation and apoptosis were investigated by flow cytometry. Real-time polymerase chain reaction was performed to evaluate pluripotent gene expression. Dual-luciferase reporter assays were performed to examine the transcriptional activity of the NANOG promoter. Western blotting was performed to identify the molecules downstream of PBX1 involved in proliferation and reprogramming. Caspase3 activity was detected to assess HF-MSC reprogramming. The phosphatidylinositol 3-kinase/AKT inhibitor LY294002 was used to inhibit the phosphorylation and activity of AKT.

RESULTS

Overexpression of PBX1 in HF-MSCs increased the phosphorylation of AKT and nuclear translocation of β-catenin, resulting in the progression of the cell cycle from G0/G1 to S phase. Moreover, transfection with a combination of five transcription factors (SOMKP) in HF-MSCs enhanced the formation of alkaline phosphatase-stained colonies compared with that in HF-MSCs transfected with a combination of four transcription factors (SOMK). PBX1 upregulated Nanog transcription by activating the promoter and promoted the expression of endogenous SOX2 and OCT4. Furthermore, PBX1 expression activated the AKT/glycogen synthase kinase (GSK) 3β pathway and reduced apoptosis during the early stages of reprogramming. Inhibition of phospho-AKT or knockdown of PBX1 promoted mitochondrion-mediated apoptosis and reduced reprogramming efficiency.

CONCLUSIONS

PBX1 enhanced HF-MSC proliferation, and HF-MSCs induced pluripotent stem cells (iPSC) generation by activating the AKT/GSK3β signaling pathway. During the reprogramming of HF-MSCs into HF-iPSCs, PBX1 activated the NANOG promoter, upregulated NANOG, and inhibited mitochondrion-mediated apoptosis via the AKT/GSK3β pathway during the early stages of reprogramming.

Pharmacological stimulation of sigma-1 receptor promotes activation of astrocyte via ERK1/2 and GSK3β signaling pathway

Astrocyte is considered to be a type of passive supportive cells that preserves neuronal activity and survival. The dysfunction of astrocytes is involved in the pathological processes of major depression. Recent studies implicate sigma-1 receptors as putative therapeutic targets for current available antidepressant drugs. However, it is absent of direct evidences whether sigma-1 receptor could promote activation of astrocyte. In the present study, we took advantage of primary astrocyte culture and a highly selective agonist of sigma-1 receptor, (+)SKF-10047 to determine the effect of sigma-1 receptor on Brdu (bromodeoxyuridine) labeling positive cells, migration as well as GFAP (glial fibrillary acidic protein) expression of astrocyte. The results showed that (+)SKF-10047 notably increased the number of Brdu labeling positive cells, migration, and the expression of GFAP in primary astrocytes, which were blocked by antagonist of sigma-1 receptor. Moreover, we also found that (+)SKF-10047 increased the phosphorylation of ERK1/2 (extracellular signal-regulated kinases 1/2) and GSK3β (glycogen synthase kinase 3β) (ser 9) in the primary astrocytes. In addition, pharmacological inhibition of ERK1/2 and GSK3β (ser 9) abolished sigma-1 receptor-promoted activation of astrocyte. Therefore, sigma-1 receptor could be considerate as a new pattern for modulating astrocytic function might emerge as therapeutic strategies.

Effects of treadmill exercise on the anxiety-like behavior through modulation of GSK3β/β-catenin signaling in the maternal separation rat pup

Maternal separation causes depression and anxiety. Exercise ameliorates maternal separation-induced depression. In this study, we investigated the effect of treadmill exercise on anxiety-like behavior in relation with glycogen synthase kinase 3 beta (GSK3β)/β-catenin pathway using maternal separation rat pups. For this study, elevated plus maze test, immunohistochemistry for serotonin (5-hydroxytryptamine, 5-HT), tryptophan hydroxylase (TPH), and western blot for total GSK3β (t-GSK3β), phosphorylated GSK3β (p-GSK3β), total β-catenin (t-β-catenin), and phosphorylated β-catenin (p-β-catenin) were conducted. The rat pups in the exercise groups were scheduled to run on a treadmill for 30 min once a day for 10 days, starting on postnatal day 21. For the rat pups in the fluoxetine-treated group, fluoxetine was orally administrated once a day for 10 consecutive days, starting on postnatal day 21. Anxiety-like behavior was appeared in the rat pups by maternal separation. Maternal separation suppressed 5-HT and TPH expression in the dorsal raphe. Maternal separation suppressed phosphorylation of GSK3β and increased phosphorylation of β-catenin in the hippocampus. However, treadmill exercise and fluoxetine treatment alleviated anxiety and increased 5-HT and TPH expression in the dorsal raphe. Treadmill exercise and fluoxetine treatment also enhanced GSK3β phosphorylation and suppressed β-catenin phosphorylation in the hippocampus. In this study, alleviating effect of treadmill exercise on maternal separation-induced anxiety appeared through enhancing 5-HT expression and GSK3β phosphorylation, and then inhibiting β-catenin phosphorylation. These results showed that treadmill exercise relieves anxiety through GSK3β/β-catenin pathway. Treadmill exercise showed similar ameliorating effect on anxiety-like behavior as fluoxetine.

MiR-1246 Promotes Metastasis and Invasion of A549 cells by Targeting GSK-3β‒Mediated Wnt/β-Catenin Pathway

PURPOSE

MicroRNAs (miRNAs) are a group of small non-coding RNAs involved in different cancers, including lung cancer. Here, we aim to investigate the expression profiles of circulating miRNAs and their roles contributed to the progress of lung cancer.

Materials and Methods

The levels of circulating miRNA in lung cancer patients were investigated by miRNAs assay. Then we predicted the target genes of aberrantly expressing miRNAs by searching genetic databases. Based on the A549 cells transfected with miR-1246 mimics or miR-1246 inhibitor,we further measured the roles of miR-1246 involving in the epithelial-mesenchymal transition (EMT), migration and invasion capacities of lung cancer cells in vitro. Finally, we detected the effects of miR-1246 on glycogen synthase kinase-3β (GSK-3β)/β-catenin pathway by immunofluorescence and Western blot, respectively.

RESULTS

We identified that 14 miRNAs were aberrantly expressed in the serum of lung cancer patients. Among them, miR-1246 was the most up-regulated. The cell assays indicated that miR-1246 significantly increased the migration and invasion capabilities of A549 lung cancer cells. Meanwhile, immunofluorescence analysis revealed that miR-1246 promoted EMT process of A549 cells accompanying with decreasing E-cadherin expression, while increasing vimentin and transforming growth factor β (TGF-β) expression. Furthermore, an online tool predicated that miR-1246 might bind to 3'-untranslated region of GSK-3β, which was confirmed by overexpression and knockdown of miR-1246 assays.

CONCLUSION

Taken together, the study illustrates that miR-1246 regulates Wnt/β-catenin pathway through targeting GSK-3β/β-catenin, which partly contributing to tumor metastasis. MiR-1246 may play an essential role in the diagnosis and therapeutic of lung cancer.

Chronic fluoride exposure induces neuronal apoptosis and impairs neurogenesis and synaptic plasticity: Role of GSK-3β/β-catenin pathway

Fluoride is becoming an ineluctable environmental pollutant and its longterm exposure would cause fluorosis and irreversible brain damage, but the molecular mechanisms remain far from fully understood. In the present study, we firstly evaluated the glycogen synthase kinase 3β (GSK-3β)/β-catenin pathway in the hippocampus of rats exposed to fluoride, given the well-established role of GSK-3β/β-catenin pathway in neuronal death and survival. Our data showed that sustained exposure to 50 mg/L and 100 mg/L NaF in drinking water dose-dependently induced neuronal loss and apoptosis in rat hippocampus. Neurogenesis was also weakened by fluoride administration in the hippocampal dentate gyrus region. Additionally, the synaptic markers, synaptophysin (SYP) and post-synaptic density 95 (PSD95) protein levels, were decreased by 100 mg/L NaF treatment, whereas 50 mg/L NaF only reduced SYP expression, indicating a compromised synaptic function. We further demonstrated that NaF, especially the higher dose, induced GSK-3β activity, with decreased inactive phosphorylated GSK-3β levels and increased GSK-3β, the active form of the kinase. Correspondingly, downstream β-catenin signaling was undermined by NaF treatment as evidenced by the fact that both two doses of NaF decreased nucleus β-catenin status and the higher dose of NaF also reduced cytoplasmic β-catenin protein expression. Taken together, the present study firstly showed the aberrant changes of GSK-3β/β-catenin signaling in the fluoride-exposed brain, highlighting the involvement of GSK-3β/β-catenin signaling in the fluoride-induced neurotoxicity.

Dexamethasone induces osteoblast apoptosis through ROS-PI3K/AKT/GSK3β signaling pathway

BACKGROUND

Osteoblasts play important roles in the process of osteogenesis and prevention of osteonecrosis. Dexamethasone (Dex), a type of glucocorticoids (GCs), induces apoptosis of osteoblasts and leads to the occurrence of non-traumatic osteonecrosis. This study aimed to explore the effects of phosphatidylinositol 3-kinase/Protein kinase 3 (PI3K/AKT) and glycogen synthase kinase 3β (GSK3β) on Dex-induced osteoblasts apoptosis.

METHODS

Viabilities, proliferation, and apoptosis of primary osteoblasts and pre-osteoblast MC3T3-E1 cells after Dex treatment were detected using cell counting kit-8 (CCK-8) assay, 5-bromo-2'-deoxyuridine (BrdU) incorporation assay, FITC-Annexin V/PI staining and western blotting, respectively. 2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) staining was performed to measure the intracellular reactive oxygen species (ROS) levels after Dex treatment. N-acetyl-l-cysteine (NAC) was used as ROS scavenger in this research. The expressions of PI3K/AKT and GSK3β in osteoblasts and MC3T3-E1 cells after Dex treatment were analyzed using western blotting and qRT-PCR, respectively. Then the effects of GSK3β knockdown on Dex-induced apoptosis of osteoblasts were explored. Alkaline phosphatase (ALP) activity assay was used to detect the role of Dex in regulating ALP activity.

RESULTS

Dex remarkably inhibited proliferation and induced apoptosis of osteoblasts and MC3T3-E1 cells. Dex potentially attenuated the osteoblast differentiation. The intracellular ROS levels were significantly increased after Dex treatment. Dex suppressed the activation of PI3K/AKT pathway in osteoblasts and MC3T3-E1 cells by down-regulating the expressions of p-PI3K and p-AKT. The expressions of GSK3β in osteoblasts and MC3T3-E1 cells were obviously up-regulated after Dex treatment. Knockdown of GSK3β alleviated Dex-induced osteoblast and MC3T3-E1 cell apoptosis by decreasing the expressions of Bax, cleaved-caspase 3, cleaved-caspase 9 and increasing the expression of Bcl-2.

CONCLUSION

Our research verified that Dex induced osteoblasts apoptosis by ROS-PI3K/AKT/GSK3β signaling pathway.

Discovery and anti-inflammatory evaluation of benzothiazepinones (BTZs) as novel non-ATP competitive inhibitors of glycogen synthase kinase-3β (GSK-3β)

Glycogen synthase kinase-3β (GSK-3β) has been identified to promote inflammation and its inhibitors have also been proven to treat some inflammatory mediated diseases in animal models. Non-ATP competitive inhibitors inherently have better therapeutical value due to their higher specificity than ATP competitive ones. In this paper, we designed and synthesized a series of new BTZ derivatives as non-ATP competitive GSK-3β inhibitors. Kinetic analysis revealed two typical compounds 6j and 3j showed the different non-ATP competitive mechanism of substrate competition or allosteric modulation to GSK-3β, respectively. As expected, the two compounds showed good specificity in a panel test of 16 protein kinases, even to the closest enzymes, like CDK-1/cyclin B and CK-II. The in vivo results proved that both compounds can greatly attenuate the LPS-induced acute lung injury (ALI) and diminish inflammation response in mice by inhibiting the mRNA expression of IL-1β and IL-6. Western blot analysis demonstrated that they negatively regulated GSK-3β, and the mechanism of the observed beneficial effects of the inhibitors may involve both the increased phosphorylation of the Ser9 residue on GSK-3β and protein expression of Sirtuin 1 (SIRT1). The results support that such novel BTZ compounds have a protective role in LPS-induced ALI, and might be attractive candidates for further development of inflammation pharmacotherapy, which greatly thanks to their inherently high selectivities by the non-ATP competitive mode of action. Finally, we proposed suggesting binding modes by Docking study to well explain the impacts of compounds on the target site.

Targeting Regulatory T Cells for Transplant Tolerance: New Insights and Future Perspectives

Background

Organ transplantation is considered the ultimate therapy for end-stage organ disease. While pharmacologic immunosuppression is the mainstay of therapeutic strategies to prolong the survival of the graft, long-term use of immunosuppressive medications carries the risk of organ toxicity, malignancies, serious opportunistic infections, and diabetes. Therapies that promote recipient tolerance in solid organ transplantation are able to improve patient outcomes by eliminating the need for long-term immunosuppression.

Summary

Establishing tolerance to an allograft has become an area of intense study and would be the ideal therapy in clinical practice. The discovery of a subset of T cells naturally committed to perform immunoregulation has led to further investigation into their role in the immunopathogenesis of transplantation. Evidence suggests that regulatory T cells (Tregs) are fundamentally involved in promoting allograft tolerance. Efforts to characterize specific markers for Tregs, while challenging, have identified Foxp3 gene expression as a crucial step in promoting the tolerance-inducing features of Tregs. A number of approaches, including those based on targeting the glycogen synthase kinase 3β signaling pathway or activating the melanocortinergic pathway, have been tested as a way to promote Treg lineage commitment and maintenance as well as to facilitate immune tolerance. In order to be effective in clinical practice, Tregs must be allospecific and possess a specific phenotype to avoid suppression of other aspects of the immune system or increasing the risk of malignancy or infections. Multiple experimental and clinical studies have demonstrated the impact of currently used immunosuppressants on the immunoregulatory activities of Tregs and their Foxp3 expression status. Pharmacological induction of tolerogenic Tregs for inducing transplant tolerance, including epigenetic therapies, is in the ascendant.

Key Messages

Therapies that promote Treg function and survival may represent a novel strategy for achieving immune tolerance in transplant patients.

[Protective effect of glycogen synthase kinase 3β inhibition via peroxisome proliferator-activated receptor alpha activation in mice with acute liver failure]

Objective: To investigate the role of the glycogen synthase kinase 3β (GSK3β) and the peroxisome proliferator-activated receptor alpha (PPARα) signaling pathway in acute liver failure and related mechanisms in a mouse model of acute liver failure induced by D-galactosamine/lipopolysaccharide (D-GalN/LPS). Methods: C57BL/6 mice were given intraperitoneal injection of D-GalN/LPS to establish a mouse model of acute liver failure. SB216763 was used to inhibit the activity of GSK3β and PPARα siRNA was used to inhibit the expression of PPARα. Western blotting was used to measure the expression of PPARα protein. The changes in liver pathology were observed to evaluate liver injury, and the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured to assess liver function. Quantitative real-time PCR was used to measure the mRNA expression of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-12p40 (IL-12p40), and PPARα. A one-way analysis of variance was used for comparison of means between multiple groups; the least significant difference test was used for data with homogeneity of variance, and the Games-Howell method was used for data with heterogeneity of variance. Results: In the mice with liver failure induced by D-GalN/LPS, GSK3β inhibition promoted the mRNA and protein expression of PPARα (F = 13.18 and 301.36, P = 0.00 and 0.00). In the mice with acute liver failure induced by D-GalN/LPS, GSK3β inhibition alleviated liver bleeding, inflammation, and necrosis and reduced the serum levels of ALT (F = 25.16, P = 0.000) and AST (F = 12.96, P = 0.001), as well as the mRNA expression of TNF-α (F = 32.17, P = 0.00), IL-1β (F = 11.57, P = 0.005), and IL-12p40 (F = 14.17, P = 0.015) in liver tissue. The inhibition of PPARα expression reversed the liver-protecting effect of GSK3β inhibition, which manifested as aggravation in liver bleeding, inflammation, and necrosis, increases in the serum levels of ALT (F = 25.16, P = 0.001) and AST (F = 12.96, P = 0.000), and an increase in the mRNA expression of TNF-α (F = 32.17, P = 0.00), IL-1β (F = 11.57, P = 0.024), and IL-12p40 (F = 14.17, P = 0.001) in liver tissue. Conclusion: In mice with acute liver failure induced by D-GalN/LPS, the GSK3β-PPARα-inflammatory factor signaling pathway may play an important role. GSK3β inhibition has a protective effect in mice with acute liver failure possibly by activating the inhibitory inflammatory factor of PPARα.

Hydroxy-substituted trans-cinnamoyl derivatives as multifunctional tools in the context of Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial pathology that requires multifaceted agents able to address its peculiar nature. In recent years, a plethora of proteins and biochemical pathways has been proposed as possible targets to counteract neurotoxicity. Although the complex scenario is not completely elucidated, close relationships are emerging among some of these actors. In particular, increasing evidence has shown that aggregation of amyloid beta (Aβ), glycogen synthase kinase 3β (GSK-3β) and oxidative stress are strictly interconnected and their concomitant modulation may have a positive and synergic effect in contrasting AD-related impairments. We designed compound 3 which demonstrated the ability to inhibit both GSK-3β (IC₅₀ = 24.36 ± 0.01 μM) and Aβ₄₂ self-aggregation (IC₅₀ = 9.0 ± 1.4 μM), to chelate copper (II) and to act as exceptionally strong radical scavenger (k_inh = 6.8 ± 0.5 · 10⁵ M^-1s^-1) even in phosphate buffer at pH 7.4 (k_inh = 3.2 ± 0.5 · 10⁵ M^-1s^-1). Importantly, compound 3 showed high-predicted blood-brain barrier permeability, did not exert any significant cytotoxic effects in immature cortical neurons up to 50 μM and showed neuroprotective properties at micromolar concentration against toxic insult induced by glutamate.

Ablation of periostin inhibits post-infarction myocardial regeneration in neonatal mice mediated by the phosphatidylinositol 3 kinase/glycogen synthase kinase 3β/cyclin D1 signalling pathway

AIMS

To resolve the controversy as to whether periostin plays a role in myocardial regeneration after myocardial infarction (MI), we created a neonatal mouse model of MI to investigate the influence of periostin ablation on myocardial regeneration and clarify the underlying mechanisms.

METHODS AND RESULTS

Neonatal periostin-knockout mice and their wildtype littermates were subjected to MI or sham surgery. In the wildtype mice after MI, fibrosis was detectable at 3 days and fibrotic tissue was completely replaced by regenerated myocardium at 21 days. In contrast, in the knockout mice, significant fibrosis in the infarcted area was present at even 3 weeks after MI. Levels of phosphorylated-histone 3 and aurora B in the myocardium, detected by immunofluorescence and western blotting, were significantly lower in knockout than in wildtype mice at 7 days after MI. Similarly, angiogenesis was decreased in the knockout mice after MI. Expression of both the endothelial marker CD-31 and α-smooth muscle actin was markedly lower in the knockout than in wildtype mice at 7 days after MI. The knockout MI group had elevated levels of glycogen synthase kinase (GSK) 3β and decreased phosphatidylinositol 3-kinase (PI3K), phosphorylated serine/threonine protein kinase B (p-Akt), and cyclin D1, compared with the wildtype MI group. Similar effects were observed in experiments using cultured cardiomyocytes from neonatal wildtype or periostin knockout mice. Administration of SB216763, a GSK3β inhibitor, to knockout neonatal mice decreased myocardial fibrosis and increased angiogenesis in the infarcted area after MI.

CONCLUSION

Ablation of periostin suppresses post-infarction myocardial regeneration by inhibiting the PI3K/GSK3β/cyclin D1 signalling pathway, indicating that periostin is essential for myocardial regeneration.

GSK3β attenuates TGF-β1 induced epithelial-mesenchymal transition and metabolic alterations in ARPE-19 cells

While TGF-β1 is known to induce epithelial-mesenchymal transition (EMT), a major factor in the pathogenesis of proliferative vitreoretinopathy (PVR), in ARPE-19 cells. The molecular pathways involved in EMT formation have not yet to be fully characterized. In this study, we have found that TGF-β1-mediated induction of EMT in ARPE-19 cells varied in a dose- and time-dependent manner. Specifically, TGF-β1 inhibited GSK-3β by accelerating phosphorylation at ser9. GSK-3β inhibitor or knockdown of GSK-3β resulted in enhanced TGF-β1-mediated EMT, migration and collagen contraction in ARPE-19 cells, which were then abrogated by GSK-3β overexpression and PI3K/AKT inhibitor. Importantly, GSK-3β also mediated metabolic reprogramming in TGF-β1-treated cells. Our results indicate that GSK-3β plays a pivotal role in TGF-β1-mediated EMT in ARPE-19 cells.

Salidroside reduces tau hyperphosphorylation via up-regulating GSK-3β phosphorylation in a tau transgenic Drosophila model of Alzheimer's disease

Background

Alzheimer’s disease (AD) is an age-related and progressive neurodegenerative disease that causes substantial public health care burdens. Intensive efforts have been made to find effective and safe treatment against AD. Salidroside (Sal) is the main effective component of Rhodiola rosea L., which has several pharmacological activities.

The objective of this study was to investigate the efficacy of Sal in the treatment of AD transgenic Drosophila and the associated mechanisms.

Methods

We used tau transgenic Drosophila line (TAU) in which tau protein is expressed in the central nervous system and eyes by the Gal4/UAS system. After feeding flies with Sal, the lifespan and locomotor activity were recorded. We further examined the appearance of vacuoles in the mushroom body using immunohistochemistry, and detected the levels of total glycogen synthase kinase 3β (t-GSK-3β), phosphorylated GSK-3β (p-GSK-3β), t-tau and p-tau in the brain by western blot analysis.

Results

Our results showed that the longevity was improved in salidroside-fed Drosophila groups as well as the locomotor activity. We also observed less vacuoles in the mushroom body, upregulated level of p-GSK-3β and downregulated p-tau following Sal treatment.

Conclusion

Our data presented the evidence that Sal was capable of reducing the neurodegeneration in tau transgenic Drosophila and inhibiting neuronal loss. The neuroprotective effects of Sal were associated with its up-regulation of the p-GSK-3β and down-regulation of the p-tau.

The ethanolic extract of the Eclipta prostrata L. ameliorates the cognitive impairment in mice induced by scopolamine

ETHNOPHARMACOLOGICAL RELEVANCE

Eclipta prostrata L. (Asteraceae) has been prescribed for whole body nourishment and nervine tonic in Asia. However, the effects of E. prostrata in learning and memory have not been fully explored.

AIM OF THE STUDY

To scientifically elucidate the effects of E. prostrata on cognitive functions, we examined whether E. prostrata could ameliorate a cholinergic blockade-induced memory impairment, and we also investigated the effects of E. prostrata on the synaptic plasticity in the hippocampus.

MATERIALS AND METHODS

Memory impairment was induced by scopolamine, a cholinergic muscarinic receptor antagonist. The anti-amnesic effects of the ethanolic extract of Eclipta prostrata L. (EEEP) were measured in mice by the passive avoidance, Y-maze and Morris water maze tasks. To test the effects of EEEP on synaptic plasticity, we measured long-term potentiation (LTP) in the hippocampus. We also studied several signaling molecules related to learning and memory, such as phosphorylated protein kinase B (Akt) or phosphorylated glycogen synthase kinase-3β (GSK-3β).

RESULTS

In the passive avoidance task, EEEP (50 or 100mg/kg, p.o.) significantly ameliorated the shortened step-through latency induced by scopolamine. EEEP (100mg/kg, p.o.) also showed significant increase in alternation behavior during the Y-maze task. In the Morris water maze task, scopolamine-induced a decrease in both the swimming time within the target zone and the number of crossings where the platform had been placed were significantly reversed by EEEP (50 or 100mg/kg, p.o.). Moreover, EEEP (100μg/ml) significantly enhanced hippocampal LTP without affecting basal synaptic transmission. The administration of EEEP (100mg/kg) increased the phosphorylation levels of Akt and GSK-3β in the hippocampal region.

CONCLUSION

These results suggest that EEEP has memory-ameliorating activity against scopolamine-induced cognitive impairment and facilitates LTP in the hippocampus. This could be, at least in part, mediated by the activation of the Akt-GSK-3β signaling pathway.

Glycogen metabolic reprogramming in hepatocellular carcinoma: An update

Hepatocellular carcinoma (HCC) is a highly prevalent malignant tumor. Abnormal glycogen metabolism, an important metabolism process in HCC, mainly results from the variant structure, function, and expression levels of the corresponding enzymes and proteins. This variation, also called metabolic reprogramming, can regulate glycogen metabolic pathway to promote HCC tumorigenesis. This review aims to summarize glycogen metabolism-regulated factors (including glucose transporters, glycogen synthase kinase 3β, and glycogen phosphorylase) involved in glycogen metabolic reprogramming in HCC

The role of the Wnt canonical signaling in neurodegenerative diseases

The Wnt/β-catenin or Wnt canonical pathway controls multiple biological processes throughout development and adult life. Growing evidences have suggested that deregulation of the Wnt canonical pathway could be involved in the pathogenesis of neurodegenerative diseases. The Wnt canonical signaling is a pathway tightly regulated, which activation results in the inhibition of the Glycogen Synthase Kinase 3β (GSK-3β) function and in increased β-catenin activity, that migrates into the nucleus, activating the transcription of the Wnt target genes. Conversely, when the Wnt canonical pathway is turned off, increased levels of GSK-3β promote β-catenin degradation. Hence, GSK-3β could be considered as a key regulator of the Wnt canonical pathway. Of note, GSK-3β has also been involved in the modulation of inflammation and apoptosis, determining the delicate balance between immune tolerance/inflammation and neuronal survival/neurodegeneration. In this review, we have summarized the current acknowledgements about the role of the Wnt canonical pathway in the pathogenesis of some neurodegenerative diseases including Alzheimer's disease, cerebral ischemia, Parkinson's disease, Huntington's disease, multiple sclerosis and amyotrophic lateral sclerosis, with particular regard to the main in vitro and in vivo studies in this field, by reviewing 85 research articles about.

HFS-Triggered AMPK Activation Phosphorylates GSK3β and Induces E-LTP in Rat Hippocampus In Vivo

BACKGROUND

The AMP-activated protein kinase (AMPK) is a sensor of cellular energy and nutrient status, with substantial amount of cross talk with other signaling pathways, including its phosphorylation by Akt, PKA, and GSK3β.

AIMS

Various signaling pathways and energy-consuming transport of glutamate receptors subunits are required in synaptic plasticity. However, it is unknown which energy sensors integrate the signaling pathways in these processes. In this article, we elucidated the role of AMPK activation and GSK3β phosphorylation after HFS during the inducement of early-phase long-term potentiation (E-LTP).

METHODS

Synaptic LTP in vivo was induced by high-frequency stimulation (HFS at 200 Hz at a 5-s interval). In addition, phosphorylation of AMPK and glycogen synthase kinase 3β (GSK3β) were measured using Western blotting. The amount of hippocampal AMP, ADP and ATP was measured by HPLC.

RESULTS

We showed that the phosphorylation of AMPK and GSK3β was significantly increased by HFS in vivo. HFS-induced AMPK activation occurred via increased (AMP + ADP)/ATP ratio and activation of Ca(2+) /calmodulin-dependent kinase kinase beta (CaMKKβ). Pharmacological inhibition of AMPK by compound C (CC) prevented HFS-induced inhibitory phosphorylation of GSK3β and the induction of LTP in dentate gyrus (DG) area in vivo.

CONCLUSIONS

Our findings reveal that HFS-triggered AMPK activation phosphorylates GSK3β and induces E-LTP in vivo.

P2X7 nucleotide receptor signaling potentiates the Wnt/β-catenin pathway in cells of the osteoblast lineage

The P2X7 and Wnt/β-catenin signaling pathways regulate osteoblast differentiation and are critical for the anabolic responses of bone to mechanical loading. However, whether these pathways interact to control osteoblast activity is unknown. The purpose of this study was to investigate the effects of P2X7 activation on Wnt/β-catenin signaling in osteoblasts. Using MC3T3-E1 cells, we found that combined treatment with Wnt3a and the P2X7 agonist 2'(3')-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP) elicited more sustained β-catenin nuclear localization than that induced by Wnt3a alone. Wnt3a-induced increases in β-catenin transcriptional activity were also potentiated by treatment with BzATP. Consistent with involvement of P2X7, a high ATP concentration (1 mM) potentiated Wnt3a-induced β-catenin transcriptional activity, whereas a low concentration (10 μM) of ATP, adenosine 5'-diphosphate (ADP), or uridine 5'-triphosphate (UTP) failed to elicit a response. The potentiation of β-catenin transcriptional activity elicited by BzATP was also inhibited by two distinct P2X7 antagonists: A 438079 and A 740003. Furthermore, responses to Wnt3a in calvarial cells isolated from P2rx7 knockout mice were significantly less than in cells from wild-type controls. In MC3T3-E1 cells, BzATP increased inhibitory phosphorylation of glycogen synthase kinase 3β (GSK3β), a process that was blocked by A 438079 and diminished by inhibition of protein kinase C. Thus, P2X7 signaling may potentiate the canonical Wnt pathway through GSK3β inhibition. Taken together, we show that P2X7 activation prolongs and potentiates Wnt/β-catenin signaling. Consequently, cross-talk between P2X7 and Wnt/β-catenin pathways may modulate osteoblast activity in response to mechanical loading.

Allosteric Modulation of Sigma-1 Receptors Elicits Rapid Antidepressant Activity

AIMS

Sigma-1 receptors are involved in the pathophysiological process of several neuropsychiatric diseases such as epilepsy, depression. Allosteric modulation represents an important mechanism for receptor functional regulation. In this study, we examined antidepressant activity of the latest identified novel and selective allosteric modulator of sigma-1 receptor 3-methyl-phenyl-2, 3, 4, 5-tetrahydro-1H-benzo[d]azepin-7-ol (SOMCL-668).

METHODS AND RESULTS

A single administration of SOMCL-668 decreased the immobility time in the forced swimming test (FST) and tailing suspended test in mice, which were abolished by pretreatment of sigma-1 receptor antagonist BD1047. In the chronic unpredicted mild stress (CUMS) model, chronic application of SOMCL-668 rapidly ameliorated anhedonia-like behavior (within a week), accompanying with the enhanced expression of brain-derived neurotrophic factor (BDNF) and phosphorylation of glycogen synthase kinase 3β (GSK3β) (Ser-9) in the hippocampus. SOMCL-668 also rapidly promoted the phosphorylation of GSK3β (Ser-9) in an allosteric manner in vitro. In the cultured primary neurons, SOMCL-668 enhanced the sigma-1 receptor agonist-induced neurite outgrowth and the secretion of BDNF.

CONCLUSION

SOMCL-668, a novel allosteric modulator of sigma-1 receptors, elicits a potent and rapid acting antidepressant effect. The present data provide the first evidence that allosteric modulation of sigma-1 receptors may represent a new approach for antidepressant drug discovery.

Radiosynthesis and preliminary PET evaluation of glycogen synthase kinase 3β (GSK-3β) inhibitors containing [(11)C]methylsulfanyl, [(11)C]methylsulfinyl or [(11)C]methylsulfonyl groups

Three compounds 1-3 containing methyl-sufanyl, sufinyl, or sulfonyl groups are strong inhibitors of glycogen synthase kinase 3β (GSK-3β), an enzyme associated with Alzheimer's disease. We labeled 1-3 with (11)C for a positron emission tomography (PET) brain imaging study. A novel thiophenol precursor 4 for radiosynthesis was prepared by reacting sulfoxide 2 with trifluoroacetic anhydride. [(11)C]1 was synthesized by reacting 4 with [(11)C]methyl iodide in 52 ± 5% radiochemical yield (n = 5, based on [(11)C]CO2, corrected for decay). Oxidation of [(11)C]1 with Oxone® produced [(11)C]2 and [(11)C]3, respectively. PET with [(11)C]1 and [(11)C]3 showed 2 fold higher brain uptake of radioactivity in a mouse model of cold water stress in which GSK-3β expression was increased, than in the controls.

Puerarin induces the upregulation of glutathione levels and nuclear translocation of Nrf2 through PI3K/Akt/GSK-3β signaling events in PC12 cells exposed to lead

Oxidative stress is thought to be involved in lead-induced toxicity, especially affecting the brain. We reported previously that puerarin possesses antioxidative properties in the nervous system. Therefore, the aim of the present study was to test the hypothesis that puerarin inhibits lead acetate-induced oxidative stress in PC12 cells by interrupting phosphatidylinositol-3 kinase (PI3K)/Akt signaling through increasing glutathione (GSH) synthesis. Our results showed that puerarin attenuates oxidative stress in a concentration-dependent manner in PC12 cells exposed to lead acetate demonstrated by scavenging reactive oxygen species (ROS) and reducing lipid peroxidation (LPO). Treatment with puerarin significantly up-regulates glutamate cysteine ligase catalytic subunit (GCLc) expression both at its mRNA and protein levels, but not glutamate cysteine ligase modifier (GCLm) subunit, accompanying the elevation of cellular glutathione level. The increased nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) was not because of increased transcription of Nrf2 as Nrf2 transcript levels did not change after puerarin treatment. The effects of puerarin could be partially blocked by pharmacologic inhibition of PI3K and the glycogen synthase kinase 3β (GSK-3β) pathways with LY294002 and LiCl, respectively. On the other hand, puerarin treatment promoted Akt and GSK-3β phosphorylation in PC12 cells exposed to lead acetate. Moreover, puerarin failed to modulate the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), p-c-Jun N-terminal kinases (JNK), and p-p38 mitogen-activated protein kinase (MAPK) demonstrating some specificity for its action on the PI3K/GSK-3β pathway. These findings suggest that puerarin as a phytoestrogen might be an attractive agent for prevention and treatment of chronic diseases related to lead neurotoxicity.

Brain derived neurotrophic factor is involved in the regulation of glycogen synthase kinase 3β (GSK3β) signalling

Glycogen synthase kinase 3β (GSK3β) is involved in several biochemical processes in neurons regulating cellular survival, gene expression, cell fate determination, metabolism and proliferation. GSK3β activity is inhibited through the phosphorylation of its Ser-9 residue. In this study we sought to investigate the role of BDNF/TrkB signalling in the modulation of GSK3β activity. BDNF/TrkB signalling regulates the GSK3β activity both in vivo in the retinal tissue as well as in the neuronal cells under culture conditions. We report here for the first time that BDNF can also regulate GSK3β activity independent of its effects through the TrkB receptor signalling. Knockdown of BDNF lead to a decline in GSK3β phosphorylation without having a detectable effect on the TrkB activity or its downstream effectors Akt and Erk1/2. Treatment with TrkB receptor agonist had a stimulating effect on the GSK3β phosphorylation, but the effect was significantly less pronounced in the cells in which BDNF was knocked down. The use of TrkB receptor antagonist similarly, manifested itself in the form of downregulation of GSK3β phosphorylation, but a combined TrkB inhibition and BDNF knockdown exhibited a much stronger negative effect. In vivo, we observed reduced levels of GSK3β phosphorylation in the retinal tissues of the BDNF(+/-) animals implicating critical role of BDNF in the regulation of the GSK3β activity. Concluding, BDNF/TrkB axis strongly regulates the GSK3β activity and BDNF also exhibits GSK3β regulatory effect independent of its actions through the TrkB receptor signalling.

Expression of PI3-K, PKB and GSK-3 β in the skeletal muscle tissue of gestational diabetes mellitus

OBJECTIVE

To analyze the expression of phosphatidylinositol 3 kinase (PI3-K), protein kinase B (PKB) and glycogen synthase kinase 3 beta (GSK-3 β) in skeletal muscle tissue of gestational diabetes mellitus (GDM).

METHODS

A total of 90 cases of pregnant women were divided into observation group and control group according to the occurrence of GDM with 45 cases in either, and the expression of PI3-K, PKB, GSK-3 β mRNA expression in skeletal muscle tissue was compared between two groups.

RESULTS

The total PI3-K p85 protein was significantly higher in the observation group compared with the control group, the activity of PI3-K was lower than that of the latter; The total PKB, GSK-3 β protein in skeletal tissue had no significant difference between two groups, while the serine phosphorylation levels of PKB and GSK-3β were significantly lower in observation group compared with the control group.

CONCLUSIONS

The downregulation of PI3-K, PKB and GSK-3βin skeletal tissue of GDM caused by phosphorylation dysfunction of signaling molecules is the reason for insulin resistance and transporter function decline which lead to GDM.

Maintenance of stem cell self-renewal in head and neck cancers requires actions of GSK3β influenced by CD44 and RHAMM

Cells sorted from head and neck cancers on the basis of their high expression of CD44 have high potency for tumor initiation. These cells are also involved in epithelial to mesenchymal transition (EMT) and we have previously reported that cancer stem cells (CSCs) exist as two biologically distinct phenotypes. Both phenotypes are CD44(high) but one is also ESA(high) and maintains epithelial characteristics, the other is ESA(low) , has mesenchymal characteristics and is migratory. Examining CD44-regulated signal pathways in these cells we show that CD44, and also RHAMM, act to inhibit phosphorylation of glycogen synthase kinase 3β (GSK3β). We show that inhibitory phosphorylation reduces the formation of both "tumor spheres" and "holoclone" colonies, functional indicators of stemness. GSK3β inhibition also reduces the expression of stem cell markers such as Oct4, Sox2, and Nanog and upregulates expression of the differentiation markers Calgranulin B and Involucrin in the CD44(high) /ESA(high) cell fraction. Transition of CSCs out of EMT and back to the epithelial CSC phenotype is induced by GSK3β knockdown. These results indicate that GSK3β plays a central role in determining and maintaining the phenotypes and behavior of CSCs in vitro and are likely to be involved in controlling the growth and spread of tumors in vivo.

Redox-sensitive glycogen synthase kinase 3β-directed control of mitochondrial permeability transition: rheostatic regulation of acute kidney injury

Mitochondrial dysfunction plays a pivotal role in necroapoptotic cell death and in the development of acute kidney injury (AKI). Evidence suggests that glycogen synthase kinase (GSK) 3β resides at the nexus of multiple signaling pathways implicated in the regulation of mitochondrial permeability transition (MPT). In cultured renal tubular epithelial cells, a discrete pool of GSK3β was detected in mitochondria. Coimmunoprecipitation assay confirmed that GSK3β physically interacts with cyclophilin F and voltage-dependent anion channel (VDAC), key MPT regulators that possess multiple GSK3β phosphorylation consensus motifs, suggesting that GSK3β has a direct control of MPT. Upon a strong burst of reactive oxygen species elicited by the pro-oxidant herbicide paraquat, the activity of the redox-sensitive GSK3β was drastically enhanced. This was accompanied by augmented phosphorylation of cyclophilin F and VDAC, associated with MPT and cell death. Inhibition of GSK3β by either the selective inhibitor 4-Benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8) or forced expression of a kinase-dead mutant obliterated paraquat-induced phosphorylation of cyclophilin F and VDAC, prevented MPT, and improved cellular viability. Conversely, ectopic expression of a constitutively active GSK3β amplified the effect of paraquat on cyclophilin F and VDAC phosphorylation and sensitized cells to paraquat-induced MPT and death. In vivo, paraquat injection elicited marked oxidant stress in the kidney and resulted in acute kidney dysfunction and massive tubular apoptosis and necrosis. Consistent with in vitro findings, the activity of GSK3β was augmented in the kidney after paraquat injury, associated with increased phosphorylation of cyclophilin F and VDAC and sensitized MPT. TDZD-8 blocked GSK3β activity in the kidney, intercepted cyclophilin F and VDAC phosphorylation, prevented MPT, attenuated tubular cell death, and ameliorated paraquat-induced AKI. Our data suggest that the redox-sensitive GSK3β regulates renal tubular injury in AKI by controlling the activity of MPT regulators.

Dual effects of neuroprotection and neurotoxicity by general anesthetics: role of intracellular calcium homeostasis

Although general anesthetics have long been considered neuroprotective, there are growing concerns about neurotoxicity. Preclinical studies clearly demonstrated that commonly used general anesthetics are both neuroprotective and neurotoxic, with unclear mechanisms. Recent studies suggest that differential activation of inositol 1,4,5-trisphosphate receptors, a calcium release channel located on the membrane of endoplasmic reticulum (ER), play important role on determining the fate of neuroprotection or neurotoxicity by general anesthetics. General anesthetics at low concentrations for short duration are sublethal stress factors which induce endogenous neuroprotective mechanisms and provide neuroprotection via adequate activation of InsP3R and moderate calcium release from ER. On the other hand, general anesthetics at high concentrations for prolonged duration are lethal stress factors which induce neuronal damage by over activation of InsP3R and excessive and abnormal Ca(2+) release from ER. This review emphasizes the dual effects of both neuroprotection and neurotoxicity via differential regulation of intracellular Ca(2+) homeostasis by commonly used general anesthetics and recommends strategy to maximize neuroprotective but minimize neurotoxic effects of general anesthetics.

Distinctive microRNA signature associated of neoplasms with the Wnt/β-catenin signaling pathway

As the crucial biological regulators, microRNAs that act by suppressing their target genes are involved in a variety of pathophysiological processes. It is generally accepted that microRNAs are often dysregulated in many types of neoplasm and other human diseases. In neoplasm, microRNAs may function as oncogenes or tumor suppressors. As constitutive activation of the Wnt signaling pathway is a common feature of neoplasm and contributes to its development, progression and metastasis in various cancers, numerous studies have revealed that microRNA-mediated gene regulation are interconnected with the Wnt/β-catenin signaling pathway, forming a Wnt/β-catenin-microRNA regulatory network, which is critical to successful targeting of the Wnt/β-catenin pathway for oncotherapy. In this review, we aim to accumulate recent advances on microRNAs that work in tandem with Wnt/β-catenin signaling in tumorigenesis, with particular focus on how microRNAs affect Wnt/β-catenin activity as well as how microRNAs are regulated through the Wnt/β-catenin pathway.

Distinctive microRNA signature associated of neoplasms with the Wnt/β-catenin signaling pathway

As the crucial biological regulators, microRNAs that act by suppressing their target genes are involved in a variety of pathophysiological processes. It is generally accepted that microRNAs are often dysregulated in many types of neoplasm and other human diseases. In neoplasm, microRNAs may function as oncogenes or tumor suppressors. As constitutive activation of the Wnt signaling pathway is a common feature of neoplasm and contributes to its development, progression and metastasis in various cancers, numerous studies have revealed that microRNA-mediated gene regulation are interconnected with the Wnt/β-catenin signaling pathway, forming a Wnt/β-catenin-microRNA regulatory network, which is critical to successful targeting of the Wnt/β-catenin pathway for oncotherapy. In this review, we aim to accumulate recent advances on microRNAs that work in tandem with Wnt/β-catenin signaling in tumorigenesis, with particular focus on how microRNAs affect Wnt/β-catenin activity as well as how microRNAs are regulated through the Wnt/β-catenin pathway.

GSK3β is a checkpoint for TNF-α-mediated impaired osteogenic differentiation of mesenchymal stem cells in inflammatory microenvironments

BACKGROUND

The fate and differentiation of mesenchymal stem cells (MSCs) depend on various microenvironmental cues. In chronic inflammatory bone disease, bone regeneration is inhibited. The present study therefore sought to identify the underlying molecule mechanisms.

METHODS

We isolated periodontal ligament stem cells (PDLSCs), a new population of MSCs, from the periodontal ligament tissues of periodontitis patients and healthy controls (p-PDLSCs and h-PDLSCs). The secretion of inflammatory cytokines, like TNF-α, IL-1β, IL-6 and IL-8, after LPS stimulation was measured by ELISA. The expressions of p-GSK3β and GSK3β in two types of PDLSCs were detected by Western blot. TOPFlash was used to assay the Tcf/Lef transcriptional activity. Knockdown of GSK3β by siRNA and over-expression of GSK3β by adenoviruses were performed to confirm the role of GSK3β in the impaired osteogenic differentiation of PDLSCs under inflammatory microenvironment.

RESULTS

We demonstrated that p-PDLSCs displayed impaired osteogenic capacity than h-PDLSCs. Upon inflammatory stimulation, monocytes, but not PDLSCs, released inflammatory cytokines among which TNF-α directly act on PDLSCs and suppressed their osteogenic differentiation. TNF-α induced the phosphorylation of GSK3β, the deactivated form of GSK3β, which increased nuclear β-catenin and Lef-1 accumulation, and eventually reduced the Runx2-associated osteogenesis in PDLSCs. Over-expression of GSK3β rescued osteogenesis in TNF-α-stimulated PDLSCs, whereas inactivation of GSK3β was sufficient to liberate the β-catenin/Lef-1/Runx2 pathway.

CONCLUSION

GSK3β plays an obligatory role in the TNF-α-mediated inhibition of osteogenesis in MSCs.

GENERAL SIGNIFICANCE

The strategy to target GSK3β may provide a potential approach to bone regeneration in inflammatory microenvironments.

Role of glycogen synthase kinase 3β in protective effect of propofol against hepatic ischemia-reperfusion injury. J Surg Res. 2013;185:388-398. [PMID: 23743186 DOI: 10.1016/j.jss.2013.05.004]

BACKGROUND

It was previously reported that propofol, an intravenously administered hypnotic and anesthetic agent, protects organs from ischemia-reperfusion (I/R) injury. However, the underlying mechanisms are largely unknown. Glycogen synthase kinase 3β (GSK-3β) is known to play an important role in the oxidative stress-induced apoptosis. In this study, we investigated the role of GSK-3β and mitochondrial permeability transition pore (MPTP) in the protective effects of propofol against hepatic I/R injury.

MATERIALS AND METHODS

The left and median hepatic artery and the portal vein branches were blocked by no-damage artery clips to create the model of partial ischemia (70%), and liver lobes were subjected to warm ischemia for 30, 60, 90 min, respectively. Reperfusion of 120 min was then initiated by the removal of clamp. The MPTP opening was assessed by measuring mitochondrial large amplitude swelling and mitochondrial membrane potential.

RESULTS

Pretreatment with propofol in conditions of hepatic I/R inhibits the apoptosis of hepatocytes as evidenced by decreased terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells. Importantly, propofol suppressed the mitochondrial GSK-3β by promoting or preserving its phosphorylation at Ser9, thus restraining the opening of MPTP and preventing the mitochondrial swell and mitochondrial membrane potential collapse.

CONCLUSIONS

Propofol protects liver from I/R injury by sustaining the mitochondrial function, which is possibly involved with the modulation of MPTP and GSK-3β.