IGF-1 protects SH-SY5Y cells against MPP+-induced apoptosis via PI3K/PDK-1/Akt pathway

The involvement of Akt, mTOR, and S6K in the in vivo effect of IGF-1 on the regulation of rat cardiac Na+/K+-ATPase

BACKGROUND

We previously demonstrated that insulin-like growth factor-1 (IGF-1) regulates sodium/potassium adenosine triphosphatase (Na+/K+-ATPase) in vascular smooth muscle cells (VSMC) via phosphatidylinositol-3 kinase (PI3K). Taking into account that others' work show that IGF-1 activates the PI3K/protein kinase B (Akt) signaling pathway in many different cells, we here further questioned if the Akt/mammalian target of rapamycin (mTOR)/ribosomal protein p70 S6 kinase (S6K) pathway stimulates Na+/K+-ATPase, an essential protein for maintaining normal heart function.

METHODS AND RESULTS

There were 14 adult male Wistar rats, half of whom received bolus injections of IGF-1 (50 μg/kg) for 24 h. We evaluated cardiac Na+/K+-ATPase expression, activity, and serum IGF-1 levels. Additionally, we examined the phosphorylated forms of the following proteins: insulin receptor substrate (IRS), phosphoinositide-dependent kinase-1 (PDK-1), Akt, mTOR, S6K, and α subunit of Na+/K+-ATPase. Additionally, the mRNA expression of the Na+/K+-ATPase α1 subunit was evaluated. Treatment with IGF-1 increases levels of serum IGF-1 and stimulates Na+/K+-ATPase activity, phosphorylation of α subunit of Na+/K+-ATPase on Ser23, and protein expression of α2 subunit. Furthermore, IGF-1 treatment increased phosphorylation of IRS-1 on Tyr1222, Akt on Ser473, PDK-1 on Ser241, mTOR on Ser2481 and Ser2448, and S6K on Thr421/Ser424. The concentration of IGF-1 in serum positively correlates with Na+/K+-ATPase activity and the phosphorylated form of mTOR (Ser2448), while Na+/K+-ATPase activity positively correlates with the phosphorylated form of IRS-1 (Tyr1222) and mTOR (Ser2448).

CONCLUSION

These results indicate that the Akt/mTOR/S6K signalling pathway may be involved in the IGF-1 regulating cardiac Na+/K+-ATPase expression and activity.

Evaluation of Potential Neuroprotective Effects of Vanillin Against MPP+/MPTP-Induced Dysregulation of Dopaminergic Regulatory Mechanisms in SH-SY5Y Cells and a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative condition. The pathogenesis of PD is still unknown, and drugs available for PD treatment either have side effects or have suboptimal efficacy. Flavonoids are potent antioxidants having little toxicity with extended use, suggesting they might hold promising therapeutic potential against PD. Vanillin (Van) is a phenolic compound that has exhibited neuroprotective properties in various neurological disorders, including PD. However, the neuroprotective role of Van in PD and its underlying mechanisms are scarce and therefore need more exploration. Here, we evaluated the neuroprotective potential of Van and its associated mechanisms against MPP⁺/MPTP-induced neuronal loss in differentiated human neuroblastoma (SH-SY5Y) cells and the mouse model of PD. In the present study, Van treatment significantly enhanced the cell viability and alleviated oxidative stress, mitochondrial membrane potential, and apoptosis in MPP⁺-intoxicated SH-SY5Y cells. Moreover, Van significantly ameliorated the MPP⁺-induced dysregulations in protein expression of tyrosine hydroxylase (TH) and mRNA expressions of GSK-3β, PARP1, p53, Bcl-2, Bax, and Caspase-3 genes in SH-SY5Y cells. Similar to our in vitro results, Van significantly alleviated MPTP-induced neurobehavioral dysregulations, oxidative stress, aberrant TH protein expressions, and immunoreactivity in SNpc of mice brains. Treatment of Van also prevented MPTP-mediated loss of TH-positive intrinsic dopaminergic neurons to SNpc and TH-fibers projecting to the striatum of mice. Thus, Van exhibited promising neuroprotective properties in the current study against MPP⁺/MPTP-intoxicated SH-SY5Y cells and mice, indicating its potential therapeutic properties against PD pathology.

Insulin-like growth factor-1 reduces hyperoxia-induced lung inflammation and oxidative stress and inhibits cell apoptosis through PERK/eIF2α/ATF4/CHOP signaling

Background: Insulin-like growth factor-1 (IGF-1), a member of the insulin family, has a high degree of homology with insulin and exhibits anti-inflammatory and anti-oxidative stress properties. However, the potential protective effect of IGF-1 on hyperoxia-induced lung injury remains unknown. In this study, we aimed to explore the effects and mechanism of action of IGF-1 in hyperoxia-induced lung injury in neonatal rats. Materials and Methods: Hematoxylin-eosin staining was used to observe pathological changes in lung tissue; transmission electron microscopy was used to examine the ultrastructure, and ELISA was used to detect the level of pro-inflammatory cytokines in bronchoalveolar lavage fluid. Further, malondialdehyde, glutathione, and superoxide dismutase activities in lung tissue were evaluated. TUNEL staining was used to detect cell apoptosis, and western blot analysis was used to detect the expression of Bax, Bcl-2, Caspase-3, p-PERK, p-eIF2α, ATF4, and CHOP in the lung tissue. Moreover, the wet/dry weight ratio of lung tissue was determined. Results: Intraperitoneal injection of IGF-1 effectively reduced lung tissue damage induced by hyperoxia; production of inflammatory cells and release of pro-inflammatory cytokines, oxidative stress, and cell apoptosis. Further, IGF-1 down-regulated the expression of ATF4, CHOP, and Bax/Bcl-2, and inhibited the phosphorylation of PERK and eIF2α. Conclusion: The results suggest that IGF-1 reduces hyperoxia-induced lung inflammation and oxidative stress in neonatal rats through the PERK/eIF2α/ATF4/CHOP signaling pathway and inhibits cell apoptosis.

Neuroprotective Effects of Oligosaccharides From Periplaneta Americana on Parkinson’s Disease Models In Vitro and In Vivo

Parkinson’s disease (PD) is one of the neurodegenerative diseases that is characterized by obvious motor and some nonmotor symptoms. Various therapeutics failed in the effective treatment of PD because of impaired neurological function in the brain and various complications. Periplaneta Americana oligosaccharides (OPA), the main active ingredients extracted from the medicine residues of Periplaneta Americana (P. Americana), have been reported to exert anti-inflammatory effects. The purpose of this study was to evaluate the possible mechanisms of OPA against 1-methyl-4-phenylpyridinium (MPP⁺)-induced apotosis in SH-SY5Y cells and its potential neuroprotective effects in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD subacute model mice. The data demonstrated that OPA significantly reversed the MPP⁺-induced decrease in SH-SY5Y cell viability, reduced the proportion of apoptotic cells, and protected SH-SY5Y cells from apoptosis in a dose-dependent manner by regulating the expression of apoptosis-related genes. Furthermore, OPA also alleviated the motor dysfunction of PD model mice, prevented the loss of tyrosine hydroxylase positive cells, suppressed the apoptosis of substantia nigra cells, and improved the dysbiosis of gut microbiota in vivo, suggesting that OPA demonstrated a significantly neuroprotective effect on PD model mice. These results indicated that OPA might be the possibility of PD therapeutics with economic utility and high safety.

Electroacupuncture Attenuates Learning and Memory Impairment via PI3K/Akt Pathway in an Amyloid β25-35-Induced Alzheimer’s Disease Mouse Model

The main characteristic of Alzheimer's disease (AD) is the progressive decline of learning and memory ability. Electroacupuncture (EA) may improve AD-related learning and memory ability. However, the underlying molecular mechanism of action remains unclear. The objective of the present study was to assess the effects and the molecular mechanism of EA on learning and memory in an amyloid β_25-35 (Aβ_25-35) induced AD mouse model. The AD model was established by intracerebroventricular (ICV) administration of Aβ_25-35 oligomers. AD mice were electroacupunctured with wisdom three-needle combined with Baihui (GV20) five times per week for three consecutive weeks. The Morris water maze (MWM) and Y maze tests were applied to evaluate spatial learning and memory ability. A transmission electron microscope (TEM) was used to measure mitochondria and autophagy of hippocampal neurons, and western blot was applied to observe molecular changes in the mice hippocampus. The results suggested that EA treatment significantly alleviated learning and memory impairment related to AD, reduced mitochondria damage, improved autophagy, increased mitochondrial protein 2 (Mfn2), Beclin 1, and LC3B, and decreased the expressions of fission protein 1 (Fis1) level. Furthermore, EA further upregulated the protein expression of phosphatidylinositol 3-kinase (PI3K) and the ratio of p-Akt/Akt in the hippocampus of AD mice. This study demonstrates that EA treatment attenuates cognitive deficits, modulates mitochondrial fusion and fission, and enhances autophagy via the PI3K/Akt pathway in a mouse AD model.

CaMKK2 Promotes the Progression of Ovarian Carcinoma through the PI3K/PDK1/Akt Axis

Objective. To explore the functional role of Calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) in the progression of ovarian carcinoma (OC). Methods. RT-qPCR analysis and western blot were conducted to detect the mRNA and protein expression of CaMKK2, PI3K, PDK1 and Akt in OC tissues and cells, respectively. CCK-8 assay, transwell migration assay and flow cytometry were used to measure cell proliferation, migration and apoptosis, respectively. Results. CaMKK2, PI3K, PDK1 and Akt were highly expressed in OC tissues compared with the corresponding controls. CaMKK2 knockdown significantly suppressed the mRNA and protein expression of PI3K, PDK1 and Akt in HO8910 and OV90 cells. Moreover, CaMKK2 knockdown could dramatically repress cell proliferation, migration, and markedly elevate cell apoptosis in HO8910 and OV90 cells. Conclusions. CaMKK2 played a promotion role in OC progression via activating the PI3K/PDK1/Akt axis.

Treatment of microglia with Anti-PrP monoclonal antibodies induces neuronal apoptosis in vitro

Previous reports highlighted the neurotoxic effects caused by some motif-specific anti-PrP^C antibodies in vivo and in vitro. In the current study, we investigated the detailed alterations of the proteome with liquid chromatography–mass spectrometry following direct application of anti-PrP^C antibodies on mouse neuroblastoma cells (N2a) and mouse primary neuronal (MPN) cells or by cross-linking microglial PrP^C with anti-PrP^C antibodies prior to co-culture with the N2a/MPN cells. Here, we identified 4 (3 upregulated and 1 downregulated) and 17 (11 upregulated and 6 downregulated) neuronal apoptosis-related proteins following treatment of the N2a and N11 cell lines respectively when compared with untreated cells. In contrast, we identified 1 (upregulated) and 4 (2 upregulated and 2 downregulated) neuronal apoptosis-related proteins following treatment of MPN cells and N11 when compared with untreated cells. Furthermore, we also identified 3 (2 upregulated and 1 downregulated) and 2 (1 upregulated and 1 downregulated) neuronal apoptosis-related related proteins following treatment of MPN cells and N11 when compared to treatment with an anti-PrP antibody that lacks binding specificity for mouse PrP. The apoptotic effect of the anti-PrP antibodies was confirmed with flow cytometry following labelling of Annexin V-FITC. The toxic effects of the anti-PrP antibodies was more intense when antibody-treated N11 were co-cultured with the N2a and the identified apoptosis proteome was shown to be part of the PrP^C-interactome. Our observations provide a new insight into the prominent role played by microglia in causing neurotoxic effects following treatment with anti-PrP^C antibodies and might be relevant to explain the antibody mediated toxicity observed in other related neurodegenerative diseases such as Alzheimer.

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Antibody cross-linking neuronal PrPC induces apoptosis.

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Antibody cross-linking microglial PrPC induces neuronal apoptosis.

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Different apoptotic pathways were triggered by specific anti-PrP antibody treatments.

Inhibition of γH2AX, COX-2 and regulation of antioxidant enzymes in MPP+-exposed SH-SY5Y cells pre-treated with rutin

Many plant-derived bioactive compounds such as rutin are reportedly effective in attenuating neuronal death in most neurodegenerative disorders. Parkinson's disease (PD) is characterized by the gradual degeneration of dopaminergic neurons in the substantia nigra of the midbrain, and has previously been modelled in-vitro through the specific neurotoxic activity of 1-methyl-4-phenylpyridinium (MPP⁺) on dopaminergic neurons. Rutin is a bioflavonoid with multiple pharmacological effects, and this study investigated the neuroprotective effects of rutin in the human dopaminergic SH-SY5Y cell line using the neurotoxin MPP⁺. SH-SY5Y cells pretreated with rutin, were exposed to MPP⁺ and evaluated for cell viability, nitric oxide (NO), reactive oxygen species (ROS) and antioxidant enzymes activities. In addition, western blot techniques were used to determine the protein expression levels of γH2AX and COX-2. Rutin significantly attenuated MPP⁺-induced loss of cell viability, mitigated ROS and NO production and inhibited the disruption of antioxidant enzymes activity. It was also observed that rutin significantly reduced protein expression levels of γH2AX and COX-2 in SH-SY5Y cells treated with MPP⁺. Taken together, findings from this study tend to suggest that rutin is a promising neuroprotective compound for the treatment of PD through its effects on some of the mechanisms that characterize this neurodegenerative disease.

Liquiritigenin exerts the anti-cancer role in oral cancer via inducing autophagy-related apoptosis through PI3K/AKT/mTOR pathway inhibition in vitro and in vivo

Operative treatment on oral cancer greatly damages the chewing and language function of the patient, we aim to find better solution with fewer side effects. The anti-tumor effects of Liquiritigenin (LQ) have been explored in kinds of cancers, but not in oral cancer. In this study, our purpose is to reveal the effects of LQ on oral cancer and the associated mechanism.Cell proliferation was examined through 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and 5-Ethynyl-2'- deoxyuridine (EDU) staining. Cell apoptosis in cells and tissues were assessed by flow cytometry and terminal dexynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, respectively. Expressions of AKT and light chain 3 (LC3) were detected through Immunofluorescence. In addition, xenograft model was established by injecting the CAL-27 cells (2 × 10⁶) subcutaneously into the right flanks of mice. Expression of Ki67 and Beclin1 in tissues was valued by Immunohistochemistry (IHC).We found that cell viability of CAL-27 and SCC-9 was effectively inhibited by LQ. Besides, obvious cell apoptosis and cell autophagy were induced by LQ. In addition, PI3K/AKT/mTOR pathway was sharply inactivated by LQ in oral cancer cells. Corresponding in vivo experiments demonstrated that tumor growth was largely restricted, cell apoptosis was augmented and autophagy was enhanced by LQ. What is more, phosphorylation of AKT in tumor tissues could also be inhibited by LQ. LQ inhibited the progression of oral cancer through inducing autophagy-associated apoptosis via PI3K/AKT/mTOR pathway inhibition, revealing a new possible scheme for the treatment of oral cancer.

Role of Receptor Protein Tyrosine Phosphatase β/ζ in Neuron-Microglia Communication in a Cellular Model of Parkinson's Disease

Pleiotrophin (PTN) is a neurotrophic factor that regulates glial responses in animal models of different types of central nervous system (CNS) injuries. PTN is upregulated in the brain in different pathologies characterized by exacerbated neuroinflammation, including Parkinson’s disease. PTN is an endogenous inhibitor of Receptor Protein Tyrosine Phosphatase (RPTP) β/ζ, which is abundantly expressed in the CNS. Using a specific inhibitor of RPTPβ/ζ (MY10), we aimed to assess whether the PTN/RPTPβ/ζ axis is involved in neuronal and glial injury induced by the toxin MPP+. Treatment with the RPTPβ/ζ inhibitor MY10 alone decreased the viability of both SH-SY5Y neuroblastoma cells and BV2 microglial cultures, suggesting that normal RPTPβ/ζ function is involved in neuronal and microglial viability. We observed that PTN partially decreased the cytotoxicity induced by MPP+ in SH-SY5Y cells underpinning the neuroprotective function of PTN. However, MY10 did not seem to modulate the SH-SY5Y cell loss induced by MPP+. Interestingly, we observed that media from SH-SY5Y cells treated with MPP+ and MY10 decreases microglial viability but may elicit a neuroprotective response of microglia by upregulating Ptn expression. The data suggest a neurotrophic role of microglia in response to neuronal injury through upregulation of Ptn levels.

Identification of anti-Parkinson's Disease Lead Compounds from Aspergillus ochraceus Targeting Adenosin Receptors A2A

Two novel alkaloids compounds together with fifteen know metabolites were identified from Aspergillus ochraceus. The stereochemistry features of the new molecules were determined via HRESIMS, NMR, ECD, and XRD analyses. Amongst these, compounds two compounds exhibited potential efficacy as anti-Parkinson's disease with the EC50 values of 2.30 and 2.45 μM, respectively. ADMET prediction showed that these compounds owned favorable drug-like characteristics and safe toxicity scores towards CNS drugs. Virtual screening analyses manifested that the compounds exhibited not only robust and reliable interactions to adenosine receptors A2A , but also higher binding selectivity to A2A receptors than to A1 and A3 receptors. Molecular dynamics simulation demonstrated the reliability of molecular docking results and the stability of the complexes obtained with the novel compounds and A2A receptors in natural environments. It is the first time that anti-PD lead compounds have been identified from Aspergillus ochraceus and targeting adenosine A2A receptors.

Effect of M2 Macrophage-Derived Soluble Factors on Proliferation and Apoptosis of SH-SY5Y Cells

Macrophages play the key role in the regulation of neuroregeneration. For evaluation of the neuroregenerative potential of M2 macrophages, we studied the effect of macrophages polarized with IL-4 (M2a (IL-4)) and by efferocytosis under conditions of serum deprivation (LS, Low Serum; M2(LS)) on proliferative activity and apoptosis of SH-SY5Y cells under conditions of deficiency of growth/serum factors. Conditioned media of both M2(LS) and M2a(IL-4) stimulated proliferation of SH-SY5Y cells. Moreover, soluble factors of M2(LS) and M2a(IL-4) reduced the degree of early apoptosis of SH-SY5Y cells and the protective effect of M2(LS) was observed at earlier terms of culturing. Our findings suggest that M2 macrophages have high neuroregenerative potential that is mediated through soluble factors and manifests itself both in stimulation of proliferation and inhibition of apoptosis of SH-SY5Y cells.

Dysregulation of IGF-1/GLP-1 signaling in the progression of ALS: potential target activators and influences on neurological dysfunctions

The prominent causes for motor neuron diseases like ALS are demyelination, immune dysregulation, and neuroinflammation. Numerous research studies indicate that the downregulation of IGF-1 and GLP-1 signaling pathways plays a significant role in the progression of ALS pathogenesis and other neurological disorders. In the current review, we discussed the dysregulation of IGF-1/GLP-1 signaling in neurodegenerative manifestations of ALS like a genetic anomaly, oligodendrocyte degradation, demyelination, glial overactivation, immune deregulation, and neuroexcitation. In addition, the current review reveals the IGF-1 and GLP-1 activators based on the premise that the restoration of abnormal IGF-1/GLP-1 signaling could result in neuroprotection and neurotrophic effects for the clinical-pathological presentation of ALS and other brain diseases. Thus, the potential benefits of IGF-1/GLP-1 signal upregulation in the development of disease-modifying therapeutic strategies may prevent ALS and associated neurocomplications.

Regulation of AKT/AMPK signaling, autophagy and mitigation of apoptosis in Rutin-pretreated SH-SY5Y cells exposed to MPP. Metab Brain Dis 2021;36:315-326. [PMID: 33146846 DOI: 10.1007/s11011-020-00641-z]

Accumulating evidence suggest that apoptosis, autophagy and dysregulation of signaling pathways are common mechanisms involved in Parkinson's disease (PD) pathogenesis, and thus development of therapeutic agents targeting these mechanisms may be useful for the treatment of this disease. Although rutin (a bioflavonoid) is reported to have pharmacological benefits such as antioxidant, anti-inflammatory and antitumor activities, there are very few reports on the activity of this compound in 1-methyl-4-phenylpyridinium (MPP⁺)-induced PD models. Accordingly, we investigated the effects of rutin on apoptosis, autophagy and cell signaling markers (AKT/AMPK) in SH-SY5Y cells exposed to MPP⁺. Results show reduced changes in nuclear morphology and mitigation of caspase 3/7 and 9 activities in rutin pre-treated cells exposed to MPP⁺. Likewise, rutin regulated cell signaling pathways (AKT/AMPK) and significantly decreased protein expression levels of cleaved PARP, cytochrome c, LC3-II and p62. Also, rutin significantly increased protein expression levels of full-length caspase 3 in SH-SY5Y cells treated with MPP⁺. Transmission electron microscope (TEM) images demonstrated a reduction in autophagosomes in rutin-pretreated SH-SY5Y cells exposed to MPP⁺. These results provide experimental support for rutin's neuroprotective activity against MPP⁺-induced toxicity in SH-SY5Y cells, which is as a promising therapeutic agent for clinical trials in humans.

The neuroprotective effect of Rho-kinase Inhibition in 1-methyl-4-phenylpyridinium (MPP+)-induced cellular model of neurodegeneration

Introduction: The 1-methyl 4-phenyl 1,2,3,6-tetrahydropiridium (MPTP) induced model of neurodegeneration in Parkinson's disease (PD) is one of the most commonly used experimental models. This neurotoxic agent , or rather its metabolite MPP+, leads to inhibition of mitochondrial complex I, an increase in free radicals' production and ATP depletion, all resulting in cellular demise and death. Rho-kinase is an enzyme involved with numerous cellregulatory mechanisms, such as cytoskeleton organization, axonogenesis, vesicular transport regulation and apoptosis regulation, which are all important for cell survival. Aim: Our aim was to investigate the effects of Rho-kinase inhibition on the MPP+ induced model of neurodegeneration and the role of Akt and adenosine monophosphate-activated protein kinase (AMPK) signaling pathways in this process. Material and methods: The experiments were performed on the human neuroblastoma SHSY5Y cell line. The MTT test was used to measure the viability of the cells after the MPP+ and/ or Rho-kinase inhibitor, fasudil, treatments. Changes in activation levels, or expression of pAMPK, pAkt, AMPK and Akt, were measured using the immunoblotting method, and the protein levels were quantified by densitometry. Results: The MPP+ caused a dose-dependent decrease in cellular viability, compared to the control group (untreated cells), while fasudil treatment, prior to MPP+ exposure, improved cell viability in a dose dependant manner, compared to MPP+ treatment. Analysis of activation status of target proteins showed an increase in Akt activation after the fasudil treatment, while the AMPK activation was not significantly changed. Conclusion: Inhibition of Rho-kinase using fasudil causes a decrease in MPP+ induced cell death, which is possibly mediated by an activation of the Akt/PI3K signaling pathway.

Conditional knockout of the PDK-1 gene in osteoblasts affects osteoblast differentiation and bone formation

Osteoblasts are the main functional cells of bone formation, and they are responsible for the synthesis, secretion, and mineralization of the bone matrix. Phosphatidylinositol-3-kinase/Akt is an important signaling pathway involved in the regulation of cell proliferation, death, and survival. Some studies have shown that 3-phosphoinositide-dependent protein kinase-1 (PDK-1) plays an important role in the phosphorylation of Akt. In the present study, an osteocalcin (OCN) promoter-driven Cre-LoxP system was established to specifically delete the PDK-1 gene in osteoblasts. It was found that the size and weight of PDK-1 conditional gene knockout (cKO) mice were significantly reduced. von Kossa staining and microcomputed tomography showed that the trabecular thickness, trabecular number, and bone volume were significantly decreased, whereas trabecular separation was increased, as compared with wide-type littermates, which were characterized by a decreased bone mass. A model of distal femoral defect was established, and it was found that cKO mice delayed bone defect repair. In osteoblasts derived from PDK-1 cKO mice, the alkaline phosphatase (ALP) secretion and ability of calcium mineralization were significantly decreased, and the expressions of osteoblast-related proteins, runt-related transcription factor 2, OCN, and ALP were also clearly decreased. Moreover, the phosphorylation level of Akt and downstream factor GSK3β and their response to insulin-like growth factor-1 (IGF-1) decreased clearly. Therefore, we believe that PDK-1 plays a very important role in osteoblast differentiation and bone formation by regulating the PDK-1/Akt/GSK3β signaling pathway.

Cardioprotective effect of IGF-1 against myocardial ischemia/reperfusion injury through activation of PI3K/Akt pathway in rats in vivo

Objective

It remains unknown whether insulin-like growth factor-1 (IGF-1) can attenuate myocardial ischemia/reperfusion (I/R) injury in vivo by activating the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway. This study investigated the possible interaction of IGF-1 with the PI3K/Akt pathway in cardioprotection against in vivo myocardial I/R injury in rats.

Methods

We established a myocardial I/R model in rats through left anterior descending artery ligation for 40 minutes followed by 6 hours reperfusion. The PI3K/Akt inhibitor, LY294002 (0.3 mg/kg), was injected through the caudal vein 30 minutes before myocardial ischemia, and IGF-1 (1 µg/kg or 5 µg/kg) was injected through the caudal vein 10 minutes before myocardial ischemia.

Results

IGF-1 treatment decreased myocardial infarct size; myocardial cell apoptosis; and serum lactate dehydrogenase, creatine kinase MB, and cardiac troponin I levels in rats with myocardial I/R in vivo. Moreover, IGF-1 treatment led to significant increases in expression levels of p-Akt (Ser473) and B cell lymphoma 2, while reducing expression levels of caspase-9 mRNA and cleaved caspase-9 protein in rats with myocardial I/R. However, pretreatment with LY294002 significantly reduced the cardioprotective effects of IGF-1.

Conclusion

Treatment with IGF-1 may confer cardiac protection against in vivo myocardial I/R injury via the PI3K/Akt pathway in rats.

Effect of Vasicinone against Paraquat-Induced MAPK/p53-Mediated Apoptosis via the IGF-1R/PI3K/AKT Pathway in a Parkinson's Disease-Associated SH-SY5Y Cell Model

Vasicinone is a quinazoline alkaloid isolated from the Adhatoda vasica plant. In this study, we explored the neuroprotective effect and underlying molecular mechanism of vasicinone against paraquat-induced cellular apoptosis in SH-SY5Y cells. Vasicinone reduced the paraquat-induced loss of cell viability, rescued terminal deoxynucleotide transferase-mediated dUTP nick end-labeling (TUNEL)-positive apoptotic nuclei, and suppressed generation of reactive oxygen species (ROS) in a dose-dependent manner. Western blotting analysis revealed that vasicinone increased the phosphorylation of IGF1R/PI3K/AKT cell survival signaling molecules and downregulated the paraquat-induced, mitogen-activated protein kinase (MAPK)/c-Jun N-terminal kinase (JNK)-mediated apoptotic pathways compared to that observed in cells not treated with vasicinone. This protection depended critically on the activation of IGF1R, and the silencing of IGF1R by siRNA completely abrogated the protective effect of vasicinone in SH-SY5Y cells. Our findings indicated that vasicinone is a potential candidate for the treatment of Parkinson’s disease and possibly other oxidative stress-related neurodegenerative disorders.

Amplification of USP13 drives non-small cell lung cancer progression mediated by AKT/MAPK signaling

USP13 is emerging as a potential target in cancer therapy. However, the effect of USP13 on tumor progression is controversial. Here we focused on non-small cell lung cancer (NSCLC), a common cancer with high mortality, and studied the role of USP13 in tumor growth. By analysis of multi-level genetic database, we found USP13 is high expressed in heart among healthy primary tissues and is most amplified in lung cancer. Clinical samples of NSCLC showed tumor exhibited high USP13 level compared with adjacent normal tissues. We further utilized lung adenocarcinoma A549 and squamous carcinoma H226 cells as cell model and investigated USP13 effect by USP13 knockdown. As a results, downregulation of USP13 dramatically inhibited A549 and H226 cell proliferation by AKT/MAPK signaling and suppressed tumor growth in nude mice. Collectively, we identified USP13 as a tumor promoter in NSCLC and provide a promising target in cancer therapy.

Naomaitai Ameliorated Brain Damage in Rats with Vascular Dementia by PI3K/PDK1/AKT Signaling Pathway

Background/Aims

Naomaitai can improve blood perfusion and ameliorate the damage in the paraventricular white matter. This study was focused on observing the neuroprotective effect of Naomaitai on the vascular dementia of rat and exploring the action mechanism of PI3K/PDK1/AKT signaling pathway.

Methods

A vascular dementia model of rats was established by permanent, bilateral common carotid artery occlusion. Rats' behavior was tested by Neurological deficit score and the Morris water maze. The pathology and apoptosis were detected through HE staining and TUNEL assay. Myelin sheath loss and nerve fiber damage were detected by LFB staining. Inflammatory factors, oxidative stress, and brain damage markers were detected through ELISA. The expression of apoptosis-related proteins and PI3K/PDK1/AKT signaling pathway related proteins were measured by western blot. The expressions of PI3K, PDK1, AKT, and MBP in paraventricular white matter cells were detected by immunofluorescence.

Results

Naomaitai treatment decreased neurological function score in rats with vascular dementia, ameliorated paraventricular white matter damage caused by long-term hypoxia, and hypoperfusion reduced the brain injury markers S-100β and NSE contents, suppressed inflammatory reaction and oxidative stress, reduced IL-1β, IL-6, TNF-α, and MDA contents, and remarkably increased IL-10 and SOD contents. TUNEL and western blot assay showed that Naomaitai treatment decreased neuronal cell apoptosis, increased Bcl-2 expression, and reduced caspase-3 and Bax expression. Furthermore, we found Naomaitai inhibited PI3K and PDK1 expression and activated phosphorylated AKT protein in rats with vascular dementia. However, the protective effect of Naomatai in rats with vascular dementia was inhibited, and expression of PI3K signaling pathway-related proteins was blocked after administration of PI3K inhibitor.

Conclusion

Naomaitai can ameliorate brain damage in rats with vascular dementia, inhibit neuronal apoptosis, and have anti-inflammatory and antioxidative stress effects, which may be regulated by the PI3K/PDK1/AKT signaling pathway.

Low expression of PDK1 inhibits renal cell carcinoma cell proliferation, migration, invasion and epithelial mesenchymal transition through inhibition of the PI3K-PDK1-Akt pathway

As the most commonly occurring form of primary renal tumor, renal cell carcinoma (RCC) is a malignancy accompanied by a high mortality rate. 3-phosphoinositide-dependent protein kinase 1 (PDK1) has been established as a protein target and generated considerable interest in both the pharmaceutical and academia industry. The aim of the current study was to investigate the effect of si-PDK1 on the RCC cell apoptosis, proliferation, migration, invasion and epithelial mesenchymal transition (EMT) in connection with the PI3K-PDK1-Akt pathway. Microarray analysis from the GEO database was adopted to identify differentially expressed genes (DEGs) related to RCC, after which the positive expression of the PDK1 protein in tissue was determined accordingly. The optimal silencing si-RNA was subsequently selected and RCC cell lines 786-O and A498 were selected and transfected with either a si-PDK1 or activator of the PI3K-PDK1-Akt pathway for grouping purposes. The mRNA and protein expressions of PDK1, the PI3K-PDK1-Akt pathway-, EMT- and apoptosis-related genes were then evaluated. The effect of si-PDK1 on cell proliferation, apoptosis, invasion and migration was then analyzed. Through microarray analysis of GSE6344, GSE53757, GSE14762 and GSE781, PDK1 was examined. PDK1 was determined to be highly expressed in RCC tissues. Si-PDK1 exhibited marked reductions in relation to the mRNA and protein expression of PDK1, PI3K, AKT as well as Vimentin while elevated mRNA and protein expressions of E-cadherin were detected, which ultimately suggested that cell migration, proliferation and invasion had been inhibited coupled with enhanced levels of cell apoptosis. While a notable observation was made highlighting that the PI3K-PDK1-Akt pathway antagonized the effect of PDK1 silencing. Taken together, the key observations of this study provide evidence suggesting that high expressions of PDK1 are found in RCC, while highlighting that silencing PDK1 could inhibit RCC cell proliferation, migration, invasion and EMT by repressing the PI3K-PDK1-Akt pathway.