Phosphorylation Of Glycogen Synthase Kinase-3β Research Articles

Fisetin promotes osteoblast differentiation and osteogenesis through GSK-3β phosphorylation at Ser9 and consequent β-catenin activation, inhibiting osteoporosis

Fisetin is a bioactive flavonol that inhibits osteoclastogenesis and promotes osteoblastogenesis. However, the osteogenic activity of fisetin needs to be comprehensively elucidated. In the present study, we observed that fisetin significantly increased alkaline phosphatase (ALP) activity and bone mineralization in MC3T3-E1 preosteoblasts, accompanied by a significant increase in runt-related transcription factor 2 (RUNX2), ALP, collagen type Ⅰ alpha 1 (Col1α1), osterix (OSX), osteocalcin (OCN), and bone morphogenetic protein 4 (BMP4) expression. Furthermore, fisetin promoted vertebral formation in zebrafish larvae, with the highest fisetin concentration comparable with that observed in β-glycerophosphate treatment. Fisetin also inhibited prednisolone (PDS)-induced anti-osteoblastic genes, including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), tartrate-resistant acid phosphatase-6 (ACP6), dendritic cell-specific transmembrane protein (DC-STAMP), and cathepsin K (CTSK). Fisetin potently mitigated the PDS-induced inhibition of ALP activity and bone mineralization, as well as vertebral resorption in zebrafish larvae. Moreover, we confirmed that fisetin-induced osteogenic effect was activated through phosphorylation of glycogen synthase kinase-3β (GSK-3β) at Ser9, consequently releasing β-catenin from the destructive complex to promote its nuclear translocation. β-Catenin inhibition by FH535 and the stabilization of GSK-3β by DOI hydrochloride remarkably inhibited fisetin-induced osteogenic activities, indicating that the GSK-3β/β-catenin signaling pathway plays a vital role in fisetin-induced osteogenesis. Collectively, our findings suggest that fisetin stimulates osteogenic activity and could be used as an effective strategy to prevent bone resorption.

7,8-Dihydroxyflavone modulates bone formation and resorption and ameliorates ovariectomy-induced osteoporosis.

Imbalances in bone formation and resorption cause osteoporosis. Mounting evidence supports that brain-derived neurotrophic factor (BDNF) implicates in this process. 7,8-Dihydroxyflavone (7,8-DHF), a plant-derived small molecular TrkB agonist, mimics the functions of BDNF. We show that both BDNF and 7,8-DHF promoted the proliferation, osteogenic differentiation, and mineralization of MC3T3-E1 cells. These effects might be attributed to the activation of the Wnt/β-catenin signaling pathway as the expression of cyclin D1, phosphorylated-glycogen synthase kinase-3β (p-GSK3β), β-catenin, Runx2, Osterix, and osteoprotegerin (OPG) was all significantly up-regulated. Knockdown of β-catenin restrained the up-regulation of Runx2 and Osterix stimulated by 7,8-DHF. In particular, blocking TrkB by its specific inhibitor K252a suppressed 7,8-DHF-induced osteoblastic proliferation, differentiation, and expression of osteoblastogenic genes. Moreover, BDNF and 7,8-DHF repressed osteoclastic differentiation of RAW264.7 cells. The transcription factor c-fos and osteoclastic genes such as tartrate-resistant acid phosphatase (TRAP), matrix metalloprotein-9 (MMP-9), Adamts5 were inhibited by 7,8-DHF. More importantly, 7,8-DHF attenuated bone loss, improved trabecular microarchitecture, tibial biomechanical properties, and bone biochemical indexes in an ovariectomy (OVX) rat model. The current work highlights the dual regulatory effects that 7,8-DHF exerts on bone remodeling.

PDCD4 Negatively Regulated Osteogenic Differentiation and Bone Defect Repair of Mesenchymal Stem Cells Through GSK-3β/β-Catenin Pathway.

Mesenchymal stem cells (MSCs) have been shown to be involved in bone injury repair. Programmed cell death 4 (PDCD4) is not only a tumor suppressor gene but also plays roles in the regulation of MSC function. The aim of the study was to uncover PDCD4 potential regulatory roles and mechanisms in the osteogenic differentiation and bone defect repair of MSCs. shRNA technique was used to knock down PDCD4 expression in umbilical cord-derived mesenchymal stem cells (shPDCD4-UCMSCs). Their phenotype was characterized by flow cytometry and the differentiation potential was verified. We found that PDCD4 knockdown did not affect the surface molecule expression of UCMSCs, but significantly enhanced their osteogenic differentiation and osteogenesis-related molecule expression. Mechanistically, glycogen synthase kinase-3β (GSK-3β) phosphorylation and β-catenin expression were significantly increased in shPDCD4-UCMSCs during the osteogenic differentiation process. The β-catenin inhibitor PNU-74654 reversed shPDCD4-increased osteogenesis and osteogenesis-related molecule expression. The results of animal experiments showed that shPDCD4-UCMSCs markedly improved the defect healing in rabbits. Our findings suggest that PDCD4 acts as a negative regulator of MSC osteogenic differentiation through GSK-3β/β-catenin pathway. Targeting PDCD4 may be a way to improve MSC-mediated therapeutic effects on bone injury.

The Effects of Ginsenoside Compound K on PDGF-BB-Induced PASMCs Proliferation and Phenotypic Conversion of Pulmonary Arterial Smooth Muscle Cells

To explore the inhibitory effects of ginsenoside compound K (CK) on pulmonary arterial smooth muscle cells (PASMCs) proliferation and phenotypic conversion in vitro and investigate its related mechanisms. PASMCs cultured in vitro were examined in the study. They were induced with platelet-derived growth factor-BB (PDGF-BB) and then treated with CK. The cells were randomly assigned to the control group (receiving no treatment), the model group (PDGF-BB, 20 ng/mL), and the intervention group (20 ng/mL PDGF-BB+5 μmol/L CK). The cell proliferation was measured by CCK-8 assay (on the basis of the above group assignment, concentrations of CK was set at 1, 3, and 5 μmol/L in the intervention group, and the drug group was added, receiving 1, 3, and 5 μmol/L CK, respectively). Cell cycle and apoptosis were examined by flow cytometry. The levels of mRNA and proteins of α-smooth muscle actin ( α-SMA) and smooth muscle 22α ( SM22 α), markers of phenotypic conversion, were detected by quantitative real-time PCR and Western blot. The levels of protein expression related to Wnt/β-catenin signaling pathway were examined by Western blot. Compared with the model group, CK significantly inhibited PDGF-BB-induced proliferation of PASMCs in a dose-dependent way. The results of 5 μmol/L CK intervention were not significantly different from that of the control group ( P>0.05). Hence, 5 μmol/L CK was chosen for subsequent experiments. Separate treatment of PASMCs with CK at doses of 1, 3, and 5 μmol/L did not reveal any cytotoxicity to PASMCs ( P>0.05). CK also arrested the cell cycle of PASMCs at the G 0/G 1 phase, promoted the apoptosis of PASMCs, and reversed the mRNA and protein expression of α-SMA and SM22 α ( P<0.01). In addition, CK down-regulated the expressions of cyclin D1 and β-catenin, while it up-regulated the protein expressions of phosphorylated glycogen synthase kinase-3β (pGSK-3β)/glycogen synthase kinase-3β (GSK-3β) ( P<0.01). CK was capable of inhibiting the abnormal proliferation of PASMCs and reversing the phenotypic conversion, and its acting mechanism may be related to the Wnt/β-catenin signaling pathway, suggesting the therapeutic potential of CK in controlling pulmonary arterial hypertension.

Enolase 2-Mediated Glucose Metabolism Promotes Cell Proliferation and Survival in Acute Lymphoblastic Leukemia

Background: The metabolic profiles of cancer cells have long been acknowledged to be altered and to provide new therapeutic opportunities. Expression of glycolytic enzyme enolase 2(ENO2) was found to be closely related with clinical features of acute lymphoblastic leukemia (ALL) patients, but its functions are still unclear in ALL.Methods: We evaluated the association between ENO2 mRNA expression of bone marrow mononuclear cells(BM-MCs) and efficacy of chemotherapy, and further explored the function of ENO2 in ALL.Results: The results showed that ENO2 mRNA expression in BM-MCs was significantly decreased when patients completed induction chemotherapy and reached complete remission(CR). ENO2 mRNA expression was increased when patients suffered relapse. Functional study demonstrated that ENO2 promoted cell growth, glycolysis, and glucocorticoid-resistance, all of which were effectively inhibited when ENO2 was silenced with shRNAs. Further study found that ENO2 upregulated various glycolysis-related genes, and ENO2 enhanced Akt activity with subsequent Glycogen synthase kinase3β(GSK-3β) phosphorylation, inducing cell proliferation and glycolysis. The combination of silencing ENO2 and 2-deoxyglucose (2-DG) synergistically inhibited leukemia cell survival.Conclusion: These results indicate that ENO2 may be a biological marker for monitoring chemotherapeutic efficacy and relapse in ALL. ENO2 may provide a potential therapeutic strategy for ALL. DisclosuresNo relevant conflicts of interest to declare.

TMEM88 exhibits an antiproliferative and anti-invasive effect in bladder cancer by downregulating Wnt/β-catenin signaling.

Transmembrane protein 88 (TMEM88) acts as a novel tumor-associated protein. The dysregulation of TMEM88 has been observed in several tumor types. However, the relevance of TMEM88 in tumorigenesis is still contradictory. This study assessed the relevance of TMEM88 in bladder cancer. TMEM88 levels were found to be significantly lower in bladder cancer tissue. Upregulation of TMEM88 resulted in a dramatic decrease in the cellular proliferative and invasive abilities of bladder cancer. Upregulation of TMEM88 decreased the level of active β-catenin and prohibited the activation of the Wnt/β-catenin pathway, an effect that was associated with downregulation of glycogen synthase kinase-3β (GSK-3β) phosphorylation. Suppression of GSK-3β or overexpression of β-catenin reversed the TMEM88-induced tumor-inhibiting effects in bladder cancer. Overexpression of TMEM88 prohibited the tumor formation and growth of bladder cancer cells in nude mice. In conclusion, this study demonstrates that TMEM88 exerts an antitumor function in bladder cancer through downregulation of Wnt/β-catenin signaling.

G2 and S phase-expressed-1 acts as a putative tumor promoter in cervical cancer by enhancing Wnt/β-catenin signaling via modulation of GSK-3β.

G2 and S phase-expressed-1 (GTSE1) is currently identified as a key regulator of carcinogenesis. However, the involvement of GTSE1 in cervical cancer is unclear. The aims of this work were to explore the relationship between GTSE1 and cervical cancer. Our data elucidated high GTSE1 expression in cervical cancer tissue, which predicted a poor prognosis in cervical cancer patients. GTSE1 knockdown had tumor-suppressive effects in cervical cancer cells by inhibiting cell proliferative and invasive abilities. GTSE1 knockdown decreased the level of phosphorylated glycogen synthase kinase-3β (GSK-3β) and active β-catenin, resulted in inactivation of Wnt/β-catenin signaling. Suppression of GSK-3β remarkably abolished the GTSE1-knockdown-induced inhibitory effects on Wnt/β-catenin signaling. Suppression of Wnt/β-catenin signaling abolished the GTSE1-overexpression-induced oncogenic effects. Notably, GTSE1 knockdown impeded the in vivo tumorigenicity of cervical cancer cells. In short, this work demonstrates that GTSE1 is overexpressed in cervical cancer and GTSE1 suppression exerts a tumor-inhibiting role in cervical cancer by down-regulating Wnt/β-catenin signaling. Our work underlines a crucial relevance between GTSE1 and cervical cancer progression and suggests GTSE1 as a promising therapeutic target for cervical cancer.

PAPP-A functions as a tumor suppressor and is downregulated in renal cell carcinoma.

Pregnancy‐associated plasma protein A (PAPP‐A) is a proteolytic enzyme produced by the placenta. The expression and role of PAPP‐A in renal cell carcinoma (RCC) remain elusive. The aim of this study was to investigate the role and the molecular mechanisms of PAPP‐A in RCC. Initially, we evaluated the expression of PAPP‐A in samples from patients with RCC and cell lines by quantitative PCR, western blot and immunohistochemical staining, and examined the role of PAPP‐A in RCC cells by cell viability, colony formation and Transwell assays. Next, we investigated the molecular mechanisms regulating the tumor suppressor function of PAPP‐A. Our results demonstrated that PAPP‐A is expressed at low levels in RCC tissues and cells. Clinical data analysis revealed a significant correlation between PAPP‐A expression and RCC‐related death (P < 0.0115). Overexpression of PAPP‐A inhibited viability, proliferation, migration and invasion of RCC cells. Furthermore, PAPP‐A overexpression significantly increased phosphorylation of c‐Jun N‐terminal kinase and decreased the expression of cyclin D1, phosphorylated glycogen synthase kinase‐3β and β‐catenin. This study is the first to report that downregulation of PAPP‐A is associated with poor prognosis in patients with RCC. In conclusion, PAPP‐A may serve as a novel prognostic marker and potentially as a therapeutic target in patients with RCC.

Hepatocyte‐specific Overexpression of Fatty Acid Desaturase 1 Improves Insulin Signaling and ameliorates hypertriglyceridemia in Male Rat

Objective Decreased fatty acid desaturase 1 (Fads1) activity results in the accumulation of saturated fat, which contributes to the development of nonalcoholic steatohepatitis (NASH). The aim of this study was to determine whether hepatic overexpression of Fads1 attenuates a dietary high-fat high-fructose (HFHF)-induced metabolic phenotype. Methods Hepatocyte-specific overexpression of Fads1 was achieved via the tail vein injection of recombinant adeno-associated virus (AAV) serotype 8 containing an albumin promoter with rat Fads1 sequence. Blank vectors served as controls. Male weanling Sprague-Dawley rats were assigned to five groups and fed with chow diet, low-fat high-fructose diet with AAV8 blank control (LFHF-AAV8-Blank), LFHF-AAV8-Fads1, high-fat high-fructose diet with AAV8 blank control (HFHF-AAV8-Blank), or HFHF-AAV8-Fads1 (n=8 rats/group) for 8 weeks. Metabolic phenotypes were characterized, including body weight, level of hepatic steatosis, glucose and insulin tolerance tests (GTT, ITT). Liver, skeletal muscle and adipose tissue insulin signaling were examined by western blot. Results Hepatocyte-specific overexpression of Fads1 significantly decreased body weight gain and improved glucose tolerance, but not hepatic steatosis, in LFHF-fed rats. These effects were not evident in HFHF-fed rats. On the contrary, white adipose tissue weight was markedly reduced in HFHF-AAV8-Fads1 rats compared to HFHF-AAV8-blank control rats, and to a lesser extent in LFHF rats. Both LFHF-AAV8-Fads1 and HFHF-AAV8-Fads1 rats displayed decreased fasting plasma triglycerides and increased plasma free fatty acids compared to their AAV8-blank control rats, and this was associated with upregulation of adipose tissue hormone sensitive lipase (HSL). While phosphorylated Akt (p-Akt) expression was downregulated, phosphorylated glycogen synthase kinase 3β (GSK-3β) was upregulated by both LFHF and HFHF diet in skeletal muscle, these alterations were not evident in the liver and adipose tissue. Moreover, decreased expression of p-Akt in skeletal muscle was partially restored in HFHF-AAV8-Fads1 rats, but not in LFHF-AAV8-Fads1 rats. Conclusion Our data demonstrated that hepatocyte-specific overexpression of Fads1 leads to the improvement of metabolic phenotypes in a diet- and tissue-specific manner, and this was associated with improved insulin signaling in skeletal muscle. The underlying mechanism(s) need further investigation.

SKA3 promotes glioblastoma proliferation and invasion by enhancing the activation of Wnt/β-catenin signaling via modulation of the Akt/GSK-3β axis

Spindle and kinetochore-related complex subunit 3 (SKA3) is a key modulator of the progression of multiple tumor types. However, the involvement of SKA3 in glioblastoma (GBM) has not been well studied. The current study aimed to explore the role of SKA3 expression and the potential function of the protein in GBM. Our data showed that SKA3 expression was significantly up-regulated in GBM. Functional assays demonstrated that the knockdown of SKA3 impeded the proliferation, colony formation and invasion of GBM cells, while SKA3 overexpression produced the opposite effects. Further investigation revealed that SKA3 overexpression enhanced the activation of Wnt/β-catenin signaling, which was associated with the enhanced phosphorylation of Akt and glycogen synthase kinase-3β (GSK-3β). Notably, the inhibition of Akt markedly abrogated the SKA3 overexpression-induced promotion of Wnt/β-catenin signaling in GBM cells. Further, the inhibition of Wnt/β-catenin signaling markedly abrogated the SKA3 overexpression-induced promotion of tumor growth. In addition, the knockdown of SKA3 significantly retarded tumor formation and GBM progression in vivo. In summary, these data demonstrate that SKA3 exerts promotes tumor growth in GBM by enhancing the activation of Wnt/β-catenin signaling via modulation of the Akt/GSK-3β axis. This work highlights the pivotal role of SKA3/Akt/GSK-3β/Wnt/β-catenin signaling in the progression of GBM and suggests that SKA3 is an attractive therapeutic target with potential to be used to treat GBM.

Neuroprotective Effects of Salicin in a Gerbil Model of Transient Forebrain Ischemia by Attenuating Oxidative Stress and Activating PI3K/Akt/GSK3β Pathway.

Salicin is a major natural compound of willow bark and displays diverse beneficial biological properties, such as antioxidant activity. However, little information available for the neuroprotective potential of salicin against ischemic brain injury has been reported. Thus, this study was performed to investigate the neuroprotective potential of salicin against ischemia and reperfusion (IR) injury and its mechanisms in the hippocampus using a gerbil model of 5-min transient ischemia (TI) in the forebrain, in which a massive loss (death) of pyramidal neurons cells occurred in the subfield Cornu Ammonis 1 (CA1) among the hippocampal subregions (CA1-3) at 5 days after TI. To examine neuroprotection by salicin, gerbils were pretreated with salicin alone or together with LY294002, which is a phosphatidylinositol 3-kinase (PI3K) inhibitor, once daily for 3 days before TI. Treatment with 20 mg/kg of salicin significantly protected CA1 pyramidal neurons against the ischemic injury. Treatment with 20 mg/kg of salicin significantly reduced the TI-induced increase in superoxide anion generation and lipid peroxidation in the CA1 pyramidal neurons after TI. The treatment also reinstated the TI-induced decrease in superoxide dismutases (SOD1 and SOD2), catalase, and glutathione peroxidase in the CA1 pyramidal cells after TI. Moreover, salicin treatment significantly elevated the levels of phosphorylation of Akt and glycogen synthase kinase-3β (GSK3β), which is a major downstream target of PI3K, in the ischemic CA1. Notably, the neuroprotective effect of salicin was abolished by LY294002. Taken together, these findings clearly indicate that salicin protects against ischemic brain injury by attenuating oxidative stress and activating the PI3K/Akt/GSK3β pathway.

Antihypertrophic Memory After Regression of Exercise-Induced Physiological Myocardial Hypertrophy Is Mediated by the Long Noncoding RNA Mhrt779.

Exercise can induce physiological myocardial hypertrophy (PMH), and former athletes can live 5 to 6 years longer than nonathletic controls, suggesting a benefit after regression of PMH. We previously reported that regression of pathological myocardial hypertrophy has antihypertrophic effects. Accordingly, we hypothesized that antihypertrophic memory exists even after PMH has regressed, increasing myocardial resistance to subsequent pathological hypertrophic stress. C57BL/6 mice were submitted to 21 days of swimming training to develop PMH. After termination of exercise, PMH regressed within 1 week. PMH regression mice (exercise hypertrophic preconditioning [EHP] group) and sedentary mice (control group) then underwent transverse aortic constriction or a sham operation for 4 weeks. Cardiac remodeling and function were evaluated with echocardiography, invasive left ventricular hemodynamic measurement, and histological analysis. LncRNA sequencing, chromatin immunoprecipitation assay, and comprehensive identification of RNA-binding proteins by mass spectrometry and Western blot were used to investigate the role of Mhrt779 involved in the antihypertrophic effect induced by EHP. At 1 and 4 weeks after transverse aortic constriction, the EHP group showed less increase in myocardial hypertrophy and lower expression of the Nppa and Myh7 genes than the sedentary group. At 4 weeks after transverse aortic constriction, EHP mice had less pulmonary congestion, smaller left ventricular dimensions and end-diastolic pressure, and a larger left ventricular ejection fraction and maximum pressure change rate than sedentary mice. Quantitative polymerase chain reaction revealed that the long noncoding myosin heavy chain-associated RNA transcript Mhrt779 was one of the markedly upregulated lncRNAs in the EHP group. Silencing of Mhrt779 attenuated the antihypertrophic effect of EHP in mice with transverse aortic constriction and in cultured cardiomyocytes treated with angiotensin II, and overexpression enhanced the antihypertrophic effect. Using chromatin immunoprecipitation assay and quantitative polymerase chain reaction, we found that EHP increased histone 3 trimethylation (H3K4me3 and H3K36me3) at the a4 promoter of Mhrt779. Comprehensive identification of RNA-binding proteins by mass spectrometry and Western blot showed that Mhrt779 can bind SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4 (Brg1) to inhibit the activation of the histone deacetylase 2 (Hdac2)/phosphorylated serine/threonine kinase (Akt)/phosphorylated glycogen synthase kinase 3β(p-GSK3β) pathway induced by pressure overload. Myocardial hypertrophy preconditioning evoked by exercise increases resistance to pathological stress via an antihypertrophic effect mediated by a signal pathway of Mhrt779/Brg1/Hdac2/p-Akt/p-GSK3β.

Hypoglycemic and hypolipidemic effects of total glycosides of Cistanche tubulosa in diet/streptozotocin-induced diabetic rats

Ethnopharmacological relevanceCistanche tubulosa (Schrenk) R. Wight (Orobanchaceae) is a frequently prescribed component in many traditional herbal prescriptions which are used to treat diabetes in China. In recent studies, the antidiabetic activity of Cistanche tubulosa extracts have been confirmed. However, no systematic investigation has been reported on the total glycosides of Cistatnche tubulosa (TGCT). Aim of the studyThe present study aimed to investigate the hypoglycemic and hypolipidemic effects of TGCT and the potential mechanisms in diet/streptozotocin (STZ)-induced diabetic rats, and to chemically characterize the main constituents of TGCT. Materials and methodsThe major constituents of TGCT were characterized by HPLC/Q-TOF-MS and the analytical quantification was performed with HPLC-DAD. Type 2 diabetic rats were induced by high-fat high-sucrose diet (HFSD) and a single injection of STZ (30 mg/kg). TGCT (50 mg/kg, 100 mg/kg and 200 mg/kg) or metformin (200 mg/kg) were orally administered for 6 weeks. Body weight and calorie intake were monitored throughout the experiment. Fasting plasma glucose (FPG), oral glucose tolerance test (OGTT), area under curve of glucose (AUC-G), glycosylated hemoglobin (HbA1c), fasting insulin, serum C-peptide, glycogen content and insulin sensitivity index were tested. The levels of phosphorylated protein kinase B and phosphorylated glycogen synthase kinase 3β, the activities of hexokinase and pyruvate kinase were assayed. Meanwhile, the changes in serum lipid profiles, superoxide dismutase, glutathione peroxidase, malondialdehyde and inflammatory factors were measured. Histological of pancreas were also evaluated by haematoxylin-eosin stain. ResultsOur investigation revealed the presence of phenylethanoid glycosides (PhGs): echinacoside (500.19 ± 11.52 mg/g), acteoside (19.13 ± 1.44 mg/g) and isoacteoside (141.82 ± 5.78 mg/g) in TGCT. Pharmacological tests indicated that TGCT significantly reversed STZ-induced weight loss (11.1%, 200 mg/kg); decreased FPG (56.4%, 200 mg/kg) and HbA1c (37.4%, 200 mg/kg); ameliorated the OGTT, AUC-G and insulin sensitivity; increased glycogen content (40.8% in liver and 52.6% in muscle, 200 mg/kg) and the activities of carbohydrate metabolizing enzymes; regulated lipid profile changes and the activities of antioxidant enzymes; diminished serum markers of oxidative stress and inflammation in a dose-dependent manner (p < 0.05). ConclusionsThis study confirmed that TGCT was an effective nutritional agent for ameliorating hyperglycemia and hyperlipidemia in diet/STZ-induced diabetic rats, which might be largely attributed to the activities of TGCT on inhibitions of oxidative stress and inflammation.

Glutaredoxin 2 protects cardiomyocytes from hypoxia/reoxygenation-induced injury by suppressing apoptosis, oxidative stress, and inflammation via enhancing Nrf2 signaling

Glutaredoxin 2 (GRX2) plays a cytoprotective role under various pathological conditions. However, whether GRX2 plays a role during myocardial ischemia-reperfusion injury has not been fully elucidated. In this work, we aimed to explore the detailed role and mechanism of GRX2 in modulating hypoxia/reoxygenation (H/R)-induced cardiac injury in vitro. H/R treatment resulted in a significant increase in GRX2 expression in cardiomyocytes. GRX2 knockdown enhanced the sensitivity of cardiomyocytes to H/R-induced apoptosis, oxidative stress, and inflammation, while GRX2 up-regulation exerted a cardioprotective role in H/R-injured cardiomyocytes. Further investigations revealed that GRX2 up-regulation enhanced the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling associated with upregulation of the phosphorylation of Akt and glycogen synthase kinase-3β (GSK-3β). Akt inhibition markedly abolished GRX2-mediated activation of Nrf2, while GSK-3β inhibition reversed GRX2-knockdown-mediated inhibition of Nrf2. In addition, Nrf2 inhibition markedly abrogated GRX2-mediated protective effects against H/R-induced apoptosis, oxidative stress and inflammation. Overall, this work indicates that GRX2 protects cardiomyocytes from H/R-induced apoptosis, oxidative stress, and inflammation by enhancing Nrf2 activation via modulation of the Akt/GSK-3β axis. Our study highlights a potential relevance of GRX2 in myocardial ischemia-reperfusion injury; it may serve as an attractive target for cardioprotection.

Icarisid II promotes proliferation and neuronal differentiation of neural stem cells via activating Wnt/β-catenin signaling pathway.

Adult neurogenesis plays a vital role in maintaining cognitive functions in mammals and human beings. Mobilization of hippocampal neurogenesis has been regarded as a promising therapeutic approach to restore injured neurons in neurodegenerative diseases including Alzheimer's disease (AD). Icarisid II (ICS II), an active ingredient derived from Epimedii Folium, has been reported to exhibit multiple neuroprotective effects. In the present study, we investigated the effects of ICS II on the proliferation and differentiation of neural stem cells (NSCs) and amyloid precusor protein (APP)-overexpressing NSCs (APP-NSCs) in vitro. Our results demonstrated that ICS II dose-dependently suppressed apoptosis and elevated viability of APP-NSCs. ICS II (1 μM) potently promoted proliferation and neuronal differentiation of NSCs and APP-NSCs. ICS II (1 μM) significantly upregulated Wnt-3a expression, increased the phosphorylation of glycogen synthase kinase-3β and enhanced the nuclear transfer of β-catenin. Moreover, ICS II also promoted astrocytes to secrete Wnt-3a, which positively modulates Wnt/β-catenin signaling pathway. These findings demonstrate that ICS II promotes NSCs proliferation and neuronal differentiation partly by activating the Wnt/β-catenin signaling pathway.

KLK11 acts as a tumor-inhibitor in laryngeal squamous cell carcinoma through the inactivation of Akt/Wnt/β-catenin signaling.

Kallikrein-associated peptidase 11 (KLK11) has emerged as a key tumor-associated protein that is implicated in a wide spectrum of tumor types. However, the detailed involvement of KLK11 in laryngeal squamous cell carcinoma (LSCC) has not been well studied. The aims of our work were to evaluate whether KLK11 plays a role in LSCC. We found that both the mRNA and protein expression of KLK11 were significantly lower in LSCC tissues than in normal tissues. Low expression of KLK11 was also observed in LSCC cell lines, and the up-regulation of KLK11 caused a significant inhibitory effect on the proliferation, colony formation and invasion of LSCC cells. On the contrary, the knockdown of KLK11 markedly accelerated the proliferative and invasive abilities of LSCC cells. Molecular mechanism research revealed that KLK11 overexpression decreased the phosphorylation of glycogen synthase kinase-3β (GSK-3β) and down-regulated the expression of active β-catenin, leading to the inactivation of Wnt/β-catenin signaling in LSCC cells. Furthermore, GSK-3β inhibition markedly abrogated the KLK11-mediated suppressive effect on Wnt/β-catenin signaling. Notably, the reactivation of Wnt/β-catenin partially reversed KLK11-mediated tumor-inhibition effect in LSCC. In addition, the xenograft tumor assay demonstrated that the up-regulation of KLK11 retarded tumor formation and the growth of LSCC cells in vivo. Taken together, the findings of our work demonstrate that KLK11 exerts a tumor-inhibition role in LSCC by down-regulating Wnt/β-catenin signaling. Our work highlights a pivotal role of KLK11 in LSCC progression and suggests it as an attractive anticancer target for LSCC treatment.

Spindle and kinetochore‑associated complex subunit 3 accelerates breast cancer cell proliferation and invasion through the regulation of Akt/Wnt/β-catenin signaling.

Spindle and kinetochore‑associated complex subunit 3 (SKA3) has recently been identified as a novel regulator of carcinogenesis in multiple types of cancers. However, the function and potential regulatory mechanisms of SKA3 in breast cancer remain poorly understood. The present study was designed to gain a detailed relevance of SKA3 in breast cancer. Expression of SKA3 in breast cancer was examined via real-time quantitative PCR, western blotting and immunohistochemistry analysis. Malignant behaviors of breast cancer cells were investigated via cell counting kit-8, cell apoptosis, and transwell invasion assays. The activity of Wnt/β-catenin signaling was monitored via luciferase reporter assay. The tumorigenicity of breast cancer cells in vivo was assessed via xenograft tumor assay. SKA3 expression was elevated in breast cancer tissue and was correlated with shorter survival rates in breast cancer patients. Knockdown of SKA3 caused marked reductions in cellular proliferation and invasion in breast cancer cells, whereas SKA3 overexpression accelerated proliferation and invasion. Knockdown of SKA3 resulted in decreased Akt and glycogen synthase kinase-3β phosphorylation, and decreased expression of active β-catenin, which lead to the inactivation of Wnt/β-catenin signaling. Inhibition of Akt significantly reversed the SKA3 overexpression-induced activation of Wnt/β-catenin signaling. Inhibition of Wnt/β-catenin signaling markedly abrogated SKA3 overexpression-induced tumor-promotion effects, while re-activation of Wnt/β-catenin signaling significantly reversed SKA3 knockdown-mediated tumor-inhibition effects. Knockdown of SKA3 resulted in a significant decrease in breast cancer tumor formation in vivo. SKA3 accelerates proliferation and invasion in breast cancer through the modulation of Akt/Wnt/β-catenin signaling.

Cramming the causative mechanism of glycogen synthase kinase-3β mediated by ischemic preconditioning against ovariectomy challenged rat heart

High risks of cardiovascular diseases in women are associated with low estrogen levels. Ischemic preconditioning (IPC) exhibits protection in the heart by Glycogen synthase kinase-3β (GSK-3β) phosphorylation that inhibits the mPTP opening, and this protective action of IPC is attenuated by estrogen deficiency. An experiment was performed on female Wistar rats with/without ovariectomy (OVX). Isolated rat heart was attached with perfusion assembly. Infract size, coronary flow, LDH, CKMB and histopathology were estimated. Sham control group decreased the LDH, CKMB and infract size in normal rat heart. The IPC mediated protection of heart was attenuated in OVX rat heart. Inhibition of GSK-3β is found to enhance the threshold of mPTP opening during reperfusion. The treatment with atractyloside stuck significantly the protection of heart of IPC in normal and OVX rat heart. These observations show that downregulation of GSK-3β through an impaired opening of mPTP during reperfusion and GSK-3β might be potential adjuvant to IPC against cardiac injury in OVX challenged rats.

Protective effect and mechanism of docosahexaenoic acid on the cognitive function in female APP/PS1 mice.

Docosahexaenoic acid (DHA) has been studied for many years owing to its protective effect on the decline in brain function. DHA intake reduces the risk of Alzheimer's disease (AD) and decreases amyloid deposition; however, the underlying molecular mechanism has not been completed elucidated. In this study, the effect of DHA on the cognitive function of amyloid precursor protein (APP)/PS1 in wild-type mice and its related mechanism were investigated. Results from the Morris water maze test showed that DHA improved learning and memory function in mice. Moreover, DHA reduced neuronal damage in mice brains, as determined using Nissl staining. Unsaturated fatty acid levels in the brain of mice increased (p < 0.01) after DHA administration and saturated fatty acid levels decreased (p < 0.01). The deposition of amyloid-beta (Aβ) plaques and tau protein neurofibrillary tangles was significantly inhibited. The mechanism of action of DHA was attributed to the upregulation of the expression of β-secretase (BACE)2, which competed with BACE1 to cleave APP, thus decreasing the production of extracellular Aβ fragments (p < 0.01). The expression level of insulin-degrading enzyme was not significantly different. The expression of N-methyl-D-aspartate receptors was further downregulated and the phosphorylation of glycogen synthase kinase-3β and tau protein was inhibited (p < 0.01). These data indicated that DHA could protect cognitive function in mice by reducing Aβ plaque formation and decreasing tau phosphorylation levels.

Acylated Ghrelin Administration Inhibits Sleeve Gastrectomy - Induced Hippocampal Oxidative Stress, Apoptosis and Tau-Hyperphosphorylation by Activating the PI3K/Akt Pathway

This study investigated the impact of exogenous replacement therapy with acylated ghrelin (AG) post sleeve gastrectomy (SG) on the memory function in rats. In addition, we investigated the possible underlying mechanisms, including the effects on markers of oxidative stress, tau phosphorylation, and apoptosis. Adult male Wistar rats were divided into four groups (N = 18/group) as follows: sham (control), SG, SG+AG (100 μM), and SG+AG+LY294002 (0.25 μg/100 g). We continued all treatments daily for four weeks post-surgery. SG impaired the spatial, retention, and recognition memories as tested by the Morris water maze test, passive avoidance test, and novel object recognition test, respectively. Also, it enhanced the levels of reactive oxygen species and lipid peroxides, reduced glutathione and protein levels of Bcl-2, and increased the levels of Bax and cleaved caspase-3 in the hippocampus. In addition, SG reduced the hippocampal levels of acetylcholine and brain-derived neurotrophic factor. Concomitantly, it inhibited the hippocampal activity of Akt and increased the activity of glycogen synthase kinase 3β and tau protein phosphorylation. Exogenous administration of acylated ghrelin to rats that had undergone SG prevented memory deficits. Also, it prevented the alteration in the above-mentioned biochemical parameters, an effect that was abolished by co-administration of LY294002 (phosphoinositide 3-kinase inhibitor). In conclusion, AG replacement therapy after SG in rats protects them against memory deficits and hippocampal damage by suppressing tau protein phosphorylation, mediated by activating PI3K/Aktinduced inhibition of glycogen synthase kinase 3β.