Activation of Akt by SC79 protects myocardiocytes from oxygen and glucose deprivation (OGD)/re-oxygenation

p85α deficiency alleviates ischemia-reperfusion injury by promoting cardiomyocyte survival

Myocardial ischemia-reperfusion (I/R) injury is a prevalent cause of myocardial injury, involving a series of interconnected pathophysiological processes. However, there is currently no clinical therapy for effectively mitigating myocardial I/R injury. Here, we show that p85α protein levels increase in response to I/R injury through a comprehensive analysis of cardiac proteomics, and confirm this in the I/R-injured murine heart and failing human myocardium. Genetic inhibition of p85α in mice activates the Akt-GSK3β/Bcl-x(L) signaling pathway and ameliorates I/R-induced cardiac dysfunction, apoptosis, inflammation, and mitochondrial dysfunction. p85α silencing in cardiomyocytes alleviates hypoxia-reoxygenation (H/R) injury through activating the Akt-GSK3β/Bcl-x(L) signaling pathway, while its overexpression exacerbates the damage. Mechanistically, the interaction between MG53 and p85α triggers the ubiquitination and degradation of p85α, consequently enhancing Akt phosphorylation and ultimately having cardioprotective effects. Collectively, our findings reveal that substantial reduction of p85α and subsequently activated Akt signaling have a protective effect against cardiac I/R injury, representing an important therapeutic strategy for mitigating myocardial damage.

RIP3 orchestrates oxidative stress and pyroptosis in doxorubicin-induced cardiotoxicity through regulation of AKT/Nrf2 signaling cascade

This study was designed to explore the role of RIP3 in DOX-induced cardiotoxicity and its underlying molecular mechanisms. Our results demonstrate that RIP3 exacerbates DOX-induced cardiotoxicity through promoting oxidative stress and pyroptosis by regulating the AKT/Nuclear factor erythroid 2-related factor 2 (Nrf2) signal pathway. Inhibition of RIP3 using GSK-872 attenuated DOX-induced cardiac remodeling and contractile dysfunction. Moreover, using GSK-872 in vivo, the results revealed that inhibition of RIP3 alleviated DOX-induced cardiotoxicity by the resulting inhibition of oxidative stress and pyroptosis. In addition, inhibition of RIP3 increased the protein levels of AKT and Nrf2 in DOX-treated mouse hearts. Furthermore, the AKT inhibitor LY294002 lessened RIP3 reduction-offered protection against DOX-induced H9c2 cell injury by moderating oxidative stress and pyroptosis. Taken together, these data demonstrate that RIP3 activation orchestrates DOX-induced cardiotoxicity through elevated oxidative stress and pyroptosis in an AKT/Nrf2-dependent manner. Those findings highlight the clinical relevance and therapeutic potential of targeting RIP3 for the treatment of DOX-induced cardiotoxicity.

Effects of Akt Activator SC79 on Human M0 Macrophage Phagocytosis and Cytokine Production

Akt is an important kinase in metabolism. Akt also phosphorylates and activates endothelial and neuronal nitric oxide (NO) synthases (eNOS and nNOS, respectively) expressed in M0 (unpolarized) macrophages. We showed that e/nNOS NO production downstream of bitter taste receptors enhances macrophage phagocytosis. In airway epithelial cells, we also showed that the activation of Akt by a small molecule (SC79) enhances NO production and increases levels of nuclear Nrf2, which reduces IL-8 transcription during concomitant stimulation with Toll-like receptor (TLR) 5 agonist flagellin. We hypothesized that SC79's production of NO in macrophages might likewise enhance phagocytosis and reduce the transcription of some pro-inflammatory cytokines. Using live cell imaging of fluorescent biosensors and indicator dyes, we found that SC79 induces Akt activation, NO production, and downstream cGMP production in primary human M0 macrophages. This was accompanied by a reduction in IL-6, IL-8, and IL-12 production during concomitant stimulation with bacterial lipopolysaccharide, an agonist of pattern recognition receptors including TLR4. Pharmacological inhibitors suggested that this effect was dependent on Akt and Nrf2. Together, these data suggest that several macrophage immune pathways are regulated by SC79 via Akt. A small-molecule Akt activator may be useful in some infection settings, warranting future in vivo studies.

Inhibition of integrin binding to ligand arg-gly-asp motif induces AKT-mediated cellular senescence in hepatic stellate cells

BACKGROUND & AIMS

Hepatic stellate cells (HSCs) play an essential role in liver fibrogenesis. The induction of cellular senescence has been reported to inhibit HSC activation. Previously, we demonstrated that CWHM12, a small molecule arginine-glycine-aspartic acid (RGD) peptidomimetic compound, inhibits HSC activation. This study investigated whether the inhibitory effects of CWHM12 on HSCs affected cellular senescence.

METHODS

The immortalized human HSC lines, LX-2 and TWNT-1, were used to evaluate the effects of CWHM12 on cellular senescence via the disruption of RGD-mediated binding to integrins.

RESULTS

CWHM12 induces cell cycle arrest, senescence-associated beta-galactosidase activity, acquisition of senescence-associated secretory phenotype (SASP), and expression of senescence-associated proteins in HSCs. Further experiments revealed that the phosphorylation of AKT and murine double minute 2 (MDM2) was involved in the effects of CWHM12, and the inhibition of AKT phosphorylation reversed these effects of CWHM12 on HSCs.

CONCLUSIONS

Pharmacological inhibition of RGD-mediated integrin binding induces senescence in activated HSCs.

Neuron-secreted NLGN3 ameliorates ischemic brain injury via activating Gαi1/3-Akt signaling

We here tested the potential activity and the underlying mechanisms of neuroligin-3 (NLGN3) against ischemia-reperfusion-induced neuronal cell injury. In SH-SY5Y neuronal cells and primary murine cortical neurons, NLGN3 activated Akt-mTOR and Erk signalings, and inhibited oxygen and glucose deprivation (OGD)/re-oxygenation (OGD/R)-induced cytotoxicity. Akt activation was required for NLGN3-induced neuroprotection. Gαi1/3 mediated NLGN3-induced downstream signaling activation. NLGN3-induced Akt-S6K1 activation was largely inhibited by Gαi1/3 silencing or knockout. Significantly, NLGN3-induced neuroprotection against OGD/R was almost abolished by Gαi1/3 silencing or knockout. In vivo, the middle cerebral artery occlusion (MCAO) procedure induced NLGN3 cleavage and secretion, and increased its expression and Akt activation in mouse brain tissues. ADAM10 (A Disintegrin and Metalloproteinase 10) inhibition blocked MCAO-induced NLGN3 cleavage and secretion, exacerbating ischemic brain injury in mice. Neuronal silencing of NLGN3 or Gαi1/3 in mice also inhibited Akt activation and intensified MCAO-induced ischemic brain injury. Conversely, neuronal overexpression of NLGN3 increased Akt activation and alleviated MCAO-induced ischemic brain injury. Together, NLGN3 activates Gαi1/3-Akt signaling to protect neuronal cells from ischemia-reperfusion injury.

A small-molecule PI3Kα activator for cardioprotection and neuroregeneration

Harnessing the potential beneficial effects of kinase signalling through the generation of direct kinase activators remains an underexplored area of drug development1-5. This also applies to the PI3K signalling pathway, which has been extensively targeted by inhibitors for conditions with PI3K overactivation, such as cancer and immune dysregulation. Here we report the discovery of UCL-TRO-1938 (referred to as 1938 hereon), a small-molecule activator of the PI3Kα isoform, a crucial effector of growth factor signalling. 1938 allosterically activates PI3Kα through a distinct mechanism by enhancing multiple steps of the PI3Kα catalytic cycle and causes both local and global conformational changes in the PI3Kα structure. This compound is selective for PI3Kα over other PI3K isoforms and multiple protein and lipid kinases. It transiently activates PI3K signalling in all rodent and human cells tested, resulting in cellular responses such as proliferation and neurite outgrowth. In rodent models, acute treatment with 1938 provides cardioprotection from ischaemia-reperfusion injury and, after local administration, enhances nerve regeneration following nerve crush. This study identifies a chemical tool to directly probe the PI3Kα signalling pathway and a new approach to modulate PI3K activity, widening the therapeutic potential of targeting these enzymes through short-term activation for tissue protection and regeneration. Our findings illustrate the potential of activating kinases for therapeutic benefit, a currently largely untapped area of drug development.

Inhibition of PD-1 Alters the SHP1/2-PI3K/Akt Axis to Decrease M1 Polarization of Alveolar Macrophages in Lung Ischemia-Reperfusion Injury

Polarization of alveolar macrophages (AMs) into the M1 phenotype contributes to inflammatory responses and tissue damage that occur during lung ischemia-reperfusion injury (LIRI). Programmed cell death factor-1 (PD-1) regulates polarization of macrophages, but its role in LIRI is unknown. We examined the role of PD-1 in AM polarization in models of LIRI in vivo and in vitro. Adult Sprague-Dawley rats were subjected to ischemia-reperfusion with or without pretreatment with a PD-1 inhibitor, SHP1/2 inhibitor, or Akt activator. Lung tissue damage and infiltration by M1-type AMs were assessed. As an in vitro complement to the animal studies, rat alveolar macrophages in culture were subjected to oxygen/glucose deprivation and reoxygenation. Levels of SHP1/2 and Akt proteins were evaluated using Western blots, while levels of pro-inflammatory cytokines were measured using enzyme-linked immunosorbent assays. Injury upregulated PD-1 both in vivo and in vitro. Inhibiting PD-1 reduced the number of M1-type AMs, expression of SHP1 and SHP2, and levels of inflammatory cytokines. At the same time, it partially restored Akt activation. Similar results were observed after inhibition of SHP1/2 or activation of the PI3K/Akt pathway. PD-1 promotes polarization of AMs to the M1 phenotype and inflammatory responses through the SHP1/2-PI3K/Akt axis. Inhibiting PD-1 may be an effective therapeutic strategy to limit LIRI.

Activation of the JNKs/ATM-p53 axis is indispensable for the cytoprotection of dermal fibroblasts exposed to UVB radiation

Although UVB radiation is mainly absorbed by the epidermis, ~5-10% of its photons reach and affect the upper part of the dermis. Physiologically relevant UVB doses, able to provoke erythema, induce apoptosis in human dermal fibroblasts in vitro, as well as in the dermis of SKH-1 mice. Given the sparse and even contradictory existing information on the effect of UVB radiation on dermal fibroblasts' viability, aim of this work was to unravel the crucial signaling pathways regulating the survival of UVB-treated human dermal fibroblasts. We found that UVB radiation immediately stimulates the phosphorylation of MAPK family members, as well as Akt, and is genotoxic leading to the delayed ATM-p53 axis activation. Akt phosphorylation after UVB radiation is EGFR-mediated and EGFR inhibition leads to a further decrease of viability, while the Akt activator SC79 rescues fibroblasts to an extent by a mechanism involving Nrf2 activation. The known Nrf2 activator sulforaphane also exerts a partial protective effect, although by acting in a distinct mechanism from SC79. On the other hand, inhibition of JNKs or of the ATM-p53 axis leads to a complete loss of viability after UVB irradiation. Interestingly, JNKs activation is necessary for p53 phosphorylation, while the ATM-p53 pathway is required for the long-term activation of JNKs and Akt, reassuring the protection from UVB. Although UVB radiation results in intense and prolonged increase of intracellular ROS levels, classical anti-oxidants, such as Trolox, are unable to affect Akt, JNKs, or p53 phosphorylation and to reverse the loss of fibroblasts' viability. Collectively, here we provide evidence that the main viability-regulating UVB-triggered biochemical pathways act synergistically towards the protection of human dermal fibroblasts, with EGFR/Akt and Nrf2 serving as auxiliary anti-apoptotic machineries, while JNKs/ATM-p53 activation and interplay being overriding and indispensable for the perpetuation of cellular defense and the maintenance of cell viability.

Insight into the Role of the PI3K/Akt Pathway in Ischemic Injury and Post-Infarct Left Ventricular Remodeling in Normal and Diabetic Heart

Despite the significant decline in mortality, cardiovascular diseases are still the leading cause of death worldwide. Among them, myocardial infarction (MI) seems to be the most important. A further decline in the death rate may be achieved by the introduction of molecularly targeted drugs. It seems that the components of the PI3K/Akt signaling pathway are good candidates for this. The PI3K/Akt pathway plays a key role in the regulation of the growth and survival of cells, such as cardiomyocytes. In addition, it has been shown that the activation of the PI3K/Akt pathway results in the alleviation of the negative post-infarct changes in the myocardium and is impaired in the state of diabetes. In this article, the role of this pathway was described in each step of ischemia and subsequent left ventricular remodeling. In addition, we point out the most promising substances which need more investigation before introduction into clinical practice. Moreover, we present the impact of diabetes and widely used cardiac and antidiabetic drugs on the PI3K/Akt pathway and discuss the molecular mechanism of its effects on myocardial ischemia and left ventricular remodeling.

Small-molecule Akt-activation in airway cells induces NO production and reduces IL-8 transcription through Nrf-2

BACKGROUND

The non-cancerous functions of Akt in the airway are understudied. In some tissues, Akt phosphorylates and activates endothelial nitric oxide synthase (eNOS) to produce nitric oxide (NO) that has anti-inflammatory effects. NO production has antibacterial and antiviral effects in the airway, and increasing NO may be a useful anti-pathogen strategy. Akt also stimulates the nuclear factor erythroid 2-related factor 2 (Nrf-2) transcription factor, which transcribes antioxidant genes. Therefore, we hypothesized that activation of the Akt/eNOS pathway, which also activates Nrf-2, may have protective effects in human airway cells against injury.

METHODS

To directly test the effects of Akt signaling in the airway, we treated A549 and 16HBE cells as well as primary bronchial, nasal, and type II alveolar epithelial cells with small molecule Akt activator SC79. We examined the effects of SC79 on eNOS activation, NO production, Nrf-2 target levels, and interleukin-8 (IL-8) transcription during exposure to TNF-α or Pseudomonas flagellin (TLR5 agonist). Additionally, air-liquid interface bronchial cultures were treated with cadmium, an oxidative stressor that causes airway barrier breakdown.

RESULTS

SC79 induced a ~ twofold induction of p-eNOS and Nrf-2 protein levels blocked by PI3K inhibitor LY294002. Live cell imaging revealed SC79 increased acute NO production. Quantitative RT-PCR showed a ~ twofold increase in Nrf-2 target gene transcription. TNF-α or flagellin-induced IL-8 levels were also significantly reduced with SC79 treatment. Moreover, the transepithelial electrical resistance decrease observed with cadmium was ameliorated by SC79, likely by an acute increase in tight junction protein ZO-1 levels.

CONCLUSIONS

Together, the data presented here demonstrate SC79 activation of Akt induces potentially anti-pathogenic NO production, antioxidant gene transcription, reduces IL-8 transcription, and may protect against oxidative barrier dysfunction in a wide range of airway epithelial cells.

iKeap1 activates Nrf2 signaling to protect myocardial cells from oxygen glucose deprivation/re-oxygenation-induced oxidative injury

Nuclear factor E2-related factor 2 (Nrf2) activation could efficiently protect myocardial cells from oxygen glucose deprivation/re-oxygenation (OGDR). An ultra-large structure-based virtual screening has discovered iKeap1 as a novel, direct and potent Keap1 inhibitor. Here we found that iKeap1 efficiently activated Nrf2 signaling in H9c2 myocardial cells and primary murine myocardiocytes. iKeap1 induced Keap1-Nrf2 disassociation, cytosol Nrf2 protein stabilization and nuclear translocation. The antioxidant response element (ARE) activity and expression of Nrf2 cascade genes (HO1, NQO1 and GCLC) were increased in iKeap1-treated myocardial cells. In H9c2 cells and murine myocardiocytes, iKeap1 potently inhibited OGDR-induced oxidative injury by inhibiting reactive oxygen species (ROS) production, mitochondrial depolarization, lipid peroxidation and DNA damage. In addition, OGDR-induced myocardial cell death and apoptosis were largely ameliorated after pretreatment with the novel Keap1 inhibitor. Significantly, in H9c2 cells iKeap1-induced myocardial cytoprotection against OGDR was abolished with Nrf2 silencing or knockout (using CRISPR/Cas9 method). Moreover, CRISPR/Cas9-induced Keap1 knockout led to constitutive activation of Nrf2 cascade and inhibited OGDR-induced oxidative injury. Importantly, iKeap1 was unable to further protect Keap1-knockout H9c2 cells from OGDR. Together, iKeap1 activated Nrf2 signaling to protect myocardial cells from OGDR-induced oxidative injury and cell death.

Effect of Akt activation on apoptosis-related gene expression in the crop tissues of male and female pigeons (Columba livia)

The current study investigated whether the expression of apoptosis genes in the pigeon crops was affected by the Akt signaling pathway during crop milk formation. First, 78 pairs of adult White King pigeons were randomly assigned to 7 groups, and the expression of apoptosis-related genes and Akt signaling pathway-related proteins in the crop tissues during different breeding stages were examined. The results showed that the mRNA levels of Bak, caspase-3, caspase-6, and caspase-9 in female crops all increased and reached their highest levels at d 17 of incubation (I17). In male crops, the levels of caspase-3 and caspase-9 gene expression peaked at d 1 of chick rearing (R1). The lowest level of Bcl-2 gene expression in females was observed at I17. The expression ratios of p-Akt (Ser473)/Akt and p-Akt (Thr308)/Akt in male crops decreased to their minimum at R1, while it was observed at d 7 of chick rearing (R7) in females. Second, 36 pairs of adult pigeons were divided into 3 groups and were subjected to SC79 injections with dosages of 0, 0.02, or 0.04 mg/kg bodyweight. The SC79 injections resulted in a considerable decrease in growth performance of pigeon squabs. In male crops, the expression ratios of p-Akt (Ser473)/Akt and p-Akt (Thr308)/Akt were significantly elevated in the 0.02 mg/kg SC79 group, while in female crops, they were higher in the 0.04 mg/kg SC79 group (P < 0.05). The SC79 injection inhibited the gene expression of Bak in female crops, but enhanced the gene expression of Bcl-2 in both male and female crops. In the 0.04 mg/kg SC79 group, a 50.7 to 75.7% decrease was observed in the expression of caspase-3, caspase-6, and caspase-9 in male and female pigeon crops. Expression of the caspase-8 gene and total Akt protein in pigeon crops was not changed in different breeding stages or after SC79 injection. In conclusion, the expression of genes related to mitochondria-dependent apoptosis can be regulated by the Akt signaling pathway, which may play a potential role in pigeon milk formation.

Fibroblast Growth Factor 9 (FGF9) negatively regulates the early stage of chondrogenic differentiation

Fibroblast growth factor signaling is essential for mammalian bone morphogenesis and growth, involving membranous ossification and endochondral ossification. FGF9 has been shown to be an important regulator of endochondral ossification; however, its role in the early differentiation of chondrocytes remains unknown. Therefore, in this study, we aimed to determine the role of FGF9 in the early differentiation of chondrogenesis. We found an increase in FGF9 expression during proliferating chondrocyte hypertrophy in the mouse growth plate. Silencing of FGF9 promotes the growth of ATDC5 cells and promotes insulin-induced differentiation of ATDC5 chondrocytes, which is due to increased cartilage matrix formation and type II collagen (col2a1) and X (col10a1), Acan, Ihh, Mmp13 gene expression. Then, we evaluated the effects of AKT, GSK-3β, and mTOR. Inhibition of FGF9 significantly inhibits phosphorylation of AKT and GSK-3β, but does not affected the activation of mTOR. Furthermore, phosphorylation of inhibited AKT and GSK-3β was compensated using the AKT activator SC79, and differentiation of ATDC5 cells was inhibited. In conclusion, our results indicate that FGF9 acts as an important regulator of early chondrogenesis partly through the AKT/GSK-3β pathway.

FGF20-FGFR1 signaling through MAPK and PI3K controls sensory progenitor differentiation in the organ of Corti

BACKGROUND

Fibroblast Growth Factor 20 (FGF20)-FGF receptor 1 (FGFR1) signaling is essential for cochlear hair cell (HC) and supporting cell (SC) differentiation. In other organ systems, FGFR1 signals through several intracellular pathways including MAPK (ERK), PI3K, phospholipase C ɣ (PLCɣ), and p38. Previous studies implicated MAPK and PI3K pathways in HC and SC development. We hypothesized that one or both would be important downstream mediators of FGF20-FGFR1 signaling for HC differentiation.

RESULTS

By inhibiting pathways downstream of FGFR1 in cochlea explant cultures, we established that both MAPK and PI3K pathways are required for HC differentiation while PLCɣ and p38 pathways are not. Examining the canonical PI3K pathway, we found that while AKT is necessary for HC differentiation, it is not sufficient to rescue the Fgf20-/- phenotype. To determine whether PI3K functions downstream of FGF20, we inhibited Phosphatase and Tensin Homolog (PTEN) in Fgf20-/- explants. Overactivation of PI3K resulted in a partial rescue of the Fgf20-/- phenotype, demonstrating a requirement for PI3K downstream of FGF20. Consistent with a requirement for the MAPK pathway for FGF20-regulated HC differentiation, we show that treating Fgf20-/- explants with FGF9 increased levels of dpERK.

CONCLUSIONS

Together, these data provide evidence that both MAPK and PI3K are important downstream mediators of FGF20-FGFR1 signaling during HC and SC differentiation.

Circular RNA Involved in the Protective Effect of Malva sylvestris L. on Myocardial Ischemic/Re-Perfused Injury

Ischemic heart disease has become a major health challenge worldwide. Malva sylvestris L. (MS) is a traditional herbal medicine with anti-inflammatory properties and have been used as antioxidant and anti- inflammatory agent in infectious diseases and inflammatory diseases.In this study, we aimed at elucidating the mechanism of MS against ischemia-reperfusion (I/R)–induced injury in vivo and in vitro. The I/R animal model in rats and oxygen glucose deprivation/re-oxygenation (OGD/Re) model in H9c2 cells were used in this study. MS was used to pre-treat the rats and cells. Electrocardiogram, histology staining, qPCR, ELISA, CCK-8, and circRNA microarray were performed. We found that pre-treatment with MS extract attenuate OGD/Re-induced cell apoptosis and cell viability inhibition in H9c2 cells. In addition, pre-treatment with MS protected against I/R injury in vivo. The protective effects of MS pre-treatment were associated with inflammatory genes expression and cytokines release. Further mechanistic investigation revealed that MS protected cardiomyocytes through regulating circular RNA (circRNA). We identified a novel circRNA circ003593 that mediated the protective role of MS in vitro through NLRP3 complex, which was associated with reperfusion injury salvage kinase (RISK) signaling pathway. Conclusion: this study is the first time to demonstrate the protective role of MS on I/R injury. Our findings reveal a novel circRNA circ003593-mediated the protective role of MS through NLRP3 inflammasome. Circ003593 may serve as a potential therapeutic target for ischemic heart diseases.

Targeting the kinase insert loop of PERK selectively modulates PERK signaling without systemic toxicity in mice

Chronic activation of the unfolded protein response (UPR), notably the branch comprising the kinase PERK and the translation initiation factor eIF2α, is a pathological feature of many neurodegenerative diseases caused by protein misfolding. Partial reduction of UPR signaling at the level of phosphorylated eIF2α is neuroprotective and avoids the pancreatic toxicity caused by full inhibition of PERK kinase activity. However, other stress pathways besides the UPR converge on phosphorylated eIF2α in the integrated stress response (ISR), which is critical to normal cellular function. We explored whether partial inhibition of PERK signaling may be a better therapeutic option. PERK-mediated phosphorylation of eIF2α requires its binding to the insert loop within PERK's kinase domain, which is, itself, phosphorylated at multiple sites. We found that, as expected, Akt mediates the phosphorylation of Thr⁷⁹⁹ in PERK. This phosphorylation event reduced eIF2α binding to PERK and selectively attenuated downstream signaling independently of PERK activity and the broader ISR. Induction of Thr⁷⁹⁹ phosphorylation with a small-molecule activator of Akt similarly reduced PERK signaling and increased both neuronal and animal survival without measurable pancreatic toxicity in a mouse model of prion disease. Thus, promoting PERK phosphorylation at Thr⁷⁹⁹ to partially down-regulate PERK-eIF2α signaling while avoiding widespread ISR inhibition may be a safe therapeutic approach in neurodegenerative disease.

Ginsenoside Rh3 activates Nrf2 signaling and protects endometrial cells from oxygen and glucose deprivation-reoxygenation

Oxygen and glucose deprivation (OGD)-reoxygenation (OGDR) induces oxidative injury to endometrial cells in vitro. We tested the potential effect of ginsenoside Rh3 (GRh3) in the process. Our results show that GRh3 activated Nrf2 signaling in T-HESC cells and primary murine endometrial cells. GRh3 induced Nrf2 Ser-40 phosphorylation and Keap1-Nrf2 disassociation, causing Nrf2 protein stabilization and nuclear translocation, which led to transcription and expression of antioxidant response element-dependent genes (HO1, NQO1 and GCLC). In T-HESC cells and primary murine endometrial cells, GRh3 potently attenuated OGDR-induced reactive oxygen species production, lipid peroxidation and mitochondrial depolarization, as well as cell viability reduction and necrosis. Activation of Nrf2 is required for GRh3-induced anti-OGDR actions in endometrial cells. Nrf2 inhibition, by Nrf2 shRNA, knockout (through CRISPR-Cas9-editing) or S40T mutation, abolished GRh3-induced endometrial cell protection against OGDR. Additionally, forced activation of Nrf2, by Keap1 knockout, mimicked and nullified GRh3-induced anti-OGDR actions in T-HESC cells. Together, we conclude that GRh3 protects endometrial cells from OGDR via activation of Nrf2 signaling.

Keap1-targeting microRNA-941 protects endometrial cells from oxygen and glucose deprivation-re-oxygenation via activation of Nrf2 signaling

BACKGROUND

Mimicking ischemia-reperfusion injury, oxygen and glucose deprivation (OGD)-re-oxygenation (OGDR) applied to endometrial cells produces significant oxidative stress and programmed necrosis, which can be inhibited by nuclear-factor-E2-related factor 2 (Nrf2) signaling. MicroRNA (miRNA)-induced repression of Keap1, a Nrf2 suppressor protein that facilitates Nrf2 degradation, is novel strategy to activate Nrf2 cascade.

METHODS

MicroRNA-941 (miR-941) was exogenously expressed in HESC and primary human endometrial cells, and the Nrf2 pathway examined by Western blotting and real-time quantitative PCR analysis. The endometrial cells were treated with OGDR, cell programmed necrosis and apoptosis were tested.

RESULTS

MiR-941 is a novel Keap1-targeting miRNA that regulates Nrf2 activity. In T-HESC cells and primary human endometrial cells, ectopic overexpression of miR-941 suppressed Keap1 3'-UTR (untranslated region) expression and downregulated its mRNA/protein expression, leading to activation of the Nrf2 cascade. Conversely, inhibition of miR-941 elevated Keap1 expression and activity in endometrial cells, resulting in suppression of Nrf2 activation. MiR-941 overexpression in endometrial cells attenuated OGDR-induced oxidative stress and programmed necrosis, whereas miR-941 inhibition enhanced oxidative stress and programmed necrosis. MiR-941 overexpression and inhibition were completely ineffective in Keap1-/Nrf2-KO T-HESC cells (using CRISPR/Cas9 strategy). Restoring Keap1 expression, using an UTR-depleted Keap1 construct, abolished miR-941-induced anti-OGDR activity in T-HESC cells. Thus Keap1-Nrf2 cascade activation is required for miR-941-induced endometrial cell protection.

CONCLUSIONS

Targeting Keap1 by miR-941 activates Nrf2 cascade to protect human endometrial cells from OGDR-induced oxidative stress and programmed necrosis. Video Abstract.

microRNA-1203 targets and silences cyclophilin D to protect human endometrial cells from oxygen and glucose deprivation-re-oxygenation

Oxygen and glucose deprivation (OGD)-re-oxygenation (OGDR) stimulation to the human endometrial cells mimics ischemia-reperfusion injury. Cyclophilin D (CypD)-dependent programmed necrosis pathway mediates OGDR-induced cytotoxicity to human endometrial cells. We here identified a novel CypD-targeting miRNA, microRNA-1203 (miR-1203). In T-HESC and primary human endometrial cells, ectopic overexpression of miR-1203, using a lentiviral construct, potently downregulated the CypD 3’-untranslated region (3’-UTR) activity and its expression. Both were however upregulated in endometrial cells with forced miR-1203 inhibition by its anti-sense sequence. Functional studies demonstrated that ectopic miR-1203 overexpression in endometrial cells alleviated OGDR-induced programmed necrosis, inhibiting mitochondrial CypD-p53-adenine nucleotide translocator 1 association, mitochondrial depolarization, reactive oxygen species production, and medium lactate dehydrogenase release. Contrarily OGDR-induced programmed necrosis and cytotoxicity were intensified with forced miR-1203 inhibition in endometrial cells. Significantly, ectopic miR-1203 overexpression or inhibition failed to change OGDR-induced cytotoxicity in CypD-knockout T-HESC cells. Furthermore, ectopic miR-1203 overexpression was unable to protect T-HESC endometrial cells from OGDR when CypD was restored by an UTR-depleted CypD construct. Collectively, these results show that miR-1203 targets and silences CypD to protect human endometrial cells from OGDR

Buyang Huanwu Tang inhibits cellular epithelial-to-mesenchymal transition by inhibiting TGF-β1 activation of PI3K/Akt signaling pathway in pulmonary fibrosis model in vitro

Background

Pulmonary fibrosis (PF) is a chronic and progressive interstitial lung disease. Buyang Huanwu Tang (BYHWT), a classical traditional Chinese medicine formula, has been widely utilized for the treatment of PF in China. This present study aimed to explore the mechanism of BYHWT in the treatment of PF in vitro.

Methods

TGF-β1 stimulated human alveolar epithelial A549 cells were used as in vitro model for PF. Post the treatment of BYHWT, cell viability was measured by MTT assay, and cell morphology was observed under microscope. The epithelial-to-mesenchymal transition (EMT) markers (E-cadherin, Vimentin) and collagen I (Col I) were detected by western blot, immunofluorescence staining and real-time quantitative polymerase chain reaction. With the co-administration of activators (IGF-1, SC79) and inhibitors (LY294002, MK2206), the effect of BYHWT on PI3K/Akt pathway was analyzed by western blot.

Results

BYHWT inhibited cell growth, and prevented cell morphology changed from epithelial to fibroblasts in TGF-β1 induced A549 cells. BYHWT decreased Vimentin and Col I, while increased E-cadherin at both protein and mRNA levels. Moreover, phosphorylation of PI3K (p-PI3K) and phosphorylation of Akt (p-Akt) were significantly down-regulated by BYHWT in TGF-β1 stimulated A549 cells.

Conclusion

These results indicate that BYHWT suppressed TGF-β1-induced collagen accumulation and EMT of A549 cells by inhibiting the PI3K/Akt signaling pathway. These findings suggest that BYHWT may have potential for the treatment of PF.

SC79, a novel Akt activator, protects dopaminergic neuronal cells from MPP+ and rotenone

In pathogenesis of Parkinson's disease (PD), mitochondrial dysfunction causes substantial reactive oxygen species (ROS) production and oxidative stress, leading to dopaminergic (DA) neuronal cell death. Mitochondrial toxins, including MPP⁺ (1-methyl-4-phenylpyridinium ion) and rotenone, induce oxidative injury in cultured DA neuronal cells. The current study tested the potential effect of SC79, a first-in-class small-molecule Akt activator, against the process. In SH-SY5Y cells and primary murine DA neurons, SC79 significantly attenuated MPP⁺- and rotenone-induced viability reduction, cell death, and apoptosis. SC79 activated Akt signaling in DA neuronal cells. Akt inhibition (by LY294002 and MK-2206) or CRISPR-Cas9-mediated Akt1 knockout completely abolished SC79-induced DA neuroprotection against MPP⁺. Further studies demonstrated that SC79 attenuated MPP⁺- and rotenone-induced ROS production, mitochondrial depolarization, and lipid peroxidation in SH-SY5Y cells and primary DA neurons. Moreover, upregulation of Nrf2-dependent genes (HO1 and NQO1) and Nrf2 protein stabilization were detected in SC79-treated SH-SY5Y cells and primary DA neurons. Together we show that SC79 protects DA neuronal cells from mitochondrial toxins possibly via activation of Akt-Nrf2 signaling.

A natural diarylheptanoid protects cortical neurons against oxygen–glucose deprivation-induced autophagy and apoptosis

Objectives

This study aims to investigate the neuroprotective effects of curcumin analogues, 7-(4-Hydroxy-3-methoxyphenyl)-1-phenyl-4E-hepten-3-one (AO-2) on oxygen–glucose deprivation and re-oxygenation (OGD/R) induced injury in cortical neurons, which is a widely accepted in-vitro model for ischaemic reperfusion.

Methods

In this study, AO-2 was added to cortical neurons for 2 h as pretreatment, and then cortical neurons were subjected to OGD/R in the presence of AO-2 for 4 h. Cell viability was tested by 2′, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay and apoptosis by flow cytometry and Live & Dead cell assay. Western blot analysis detected the change in AKT/mTOR (mammalian target of rapamycin) signalling pathway.

Key findings

Treatment of AO-2 increased cell survival of OGD/R-treated cortical neurons. Transient AKT/mTOR inhibition, induction of the autophagy marker LC3-II (microtubule-associated protein 1A/1B-light chain 3 phosphatidylethanolamine conjugate), and cleavage of the apoptosis marker Caspase-3 were observed at different stages of OGD/R, and AO-2 reversed all three events. Importantly, treatment of the mTOR inhibitor rapamycin blocked the neuroprotective effects of AO-2 on reducing LC3-II and cleaved Caspase-3 expression and cancelled AO-2-mediated neuronal survival.

Conclusions

These results demonstrate that AO-2 increases resistance of cortical neurons to OGD/R by decreasing autophagy and cell apoptosis, which involves an mTOR-dependent mechanism.

Protective effects of the AKT activator SC79 on renal ischemia-reperfusion injury

BACKGROUND AND AIMS

SC79, an AKT activator, has been reported to protect experimental ischemia-elicited neuronal death, brain injury, and myocardiocyte hypoxia/reoxygenation (H/R) injury. However, the protection of SC79 from renal ischemia-reperfusion (I/R) injury and the precise mechanisms involved are unknown. Here, we investigated the effects of SC79 in renal tubular epithelial cells in vitro and in mouse kidney in vivo following hypoxia-reoxygenation (H/R) and renal I/R injury.

METHODS

The kidneys of Sprague-Dawley rats were subjected to 30 min of warm ischemia followed by 24 h of reperfusion. Murine renal tubular epithelial NRK-52E cells were subjected to hypoxia for 6 h and reoxygenation for 24 h. The NRK-52E cells and the renal I/R injury model were treated with SC79 and/or LY294002 at different times and concentrations. Serum creatinine (Cr) concentration, renal histology, cellular viability, and cell apoptosis were assessed. Levels of phospho-Akt, bad, Bim, bax, bcl-2, and bcl-XL in NRK-52E cells and renal tissues were determined by western blotting.

RESULTS

SC79 improved viability and inhibited apoptosis in NRK-52E cells following H/R. SC79 decreased serum Cr and markedly improved pathology and decreased cell apoptosis in kidneys following I/R. In addition, SC79 promoted the expression of phospho-Akt, bcl-2, and bcl-XL, and decreased the expression levels of bid, bax, and bim. PI3K inhibitor (LY294002) pre-treatment completely abolished these effects of SC79.

CONCLUSIONS

The protective role of SC79 against H/R of NRK-52E cells or renal I/R injury is related to activation of phosphorylation of AKT, resulting in a decrease in the pro-apoptotic proteins bim, bax, and bad and an increase in the anti-apoptotic proteins bcl-2 and bcl-XL induced by cell H/R and renal I/R injury.

SC79, the AKT Activator Protects Cerebral Ischemia in a Rat Model of Ischemia/Reperfusion Injury

Background

Activation of AKT pathway attenuates brain damage and neuronal apoptosis during cerebral ischemia/reperfusion (I/R) injury. SC79 is a novel, selective and highly-efficient Akt activator. This study aimed to investigate the neuroprotective effect of SC79 against cerebral I/R injury in a rat model, and to explore the possible underlying mechanisms.

Material/Methods

Male Sprague-Dawley rats received cerebral ischemia for 1 hour, followed by brain reperfusion for 0.5–24 hours. The cerebral I/R injury animal model were treated with SC79 alone or SC79 in combination with LY294002. Western blots were used to detect the levels of expression of phosphatidylinositol AKT (p-Akt), Bax, and bcl-2. Twenty-four hours after cerebral I/R, the degree of brain injury was evaluated by detecting the neurological deficit score (NDS). The infarct rate of brain tissue was observed by TTC (2, 3, 5-triphenyltetrazolium chloride) staining. TUNEL (terminal deoxynucleotidyl transferase-mediated UTP nick end labeling) staining was used to detect cell apoptosis.

Results

p-Akt was activated during early cerebral I/R at 0.5 hours, and reached the highest levels at 4 hours, then gradually decreased from 6 hours, and reached and maintained the lowest levels at 12–24 hours. Bax expression was gradually increased from 6 hours and reached the highest level at 24 hours. However, bcl-2 expression was gradually increased and reached the highest levels at 4 hours, then gradually decreased from 6 hours, and reached the lowest levels at 24 hours. Administration of SC79 decreased infarct volumes and improved neurological function significantly. LY294002 in combination with SC79 lost the capability of SC79 to resist the cerebral I/R injury. SC79 treatment alone activated p-Akt and promoted anti-apoptotic bcl-2 and inhibited anti-apoptotic Bax expression in middle cerebral artery occlusion (MCAO) mice. However, combined SC79 and LY294002 treatment abolished SC79-induced p-Akt activity, inhibited anti-apoptotic bcl-2 and promoted anti-apoptotic Bax expression in MCAO mice. Furthermore, SC79 treatment alone attenuated apoptotic neuronal cell death, but abolished this effect in SC79 in combination with LY294002 treated groups.

Conclusions

SC79 significantly increased Akt activation and reduced infarct volume and subsequently improved neurological function in ischemic brain after cerebral I/R injury in rats. These findings suggested that SC79 may be as a neuroprotective drug to be potentially used in the clinic.

Protective Effects the Akt Activator SC79 in Hepatic Ischemia-Reperfusion Injury

BACKGROUND SC79 has been reported to protect against experimental ischemia-elicited neuronal death and brain injury and to protect myocardiocytes from hypoxia/reoxygenation (H/R) injury. Here, we investigated the effects of SC79 in primary hepatocytes in vitro and in rat liver in vivo following hypoxia-reoxygenation (H/R) and hepatic I/R injury. MATERIAL AND METHODS The livers of Sprague-Dawley rats were subjected to 45 min of ischemia followed by 2-24 h of reperfusion. The primary hepatocytes were subjected to hypoxia for 6 h and for 2-24 h. The hepatocytes cells or the hepatic I/R injury model livers were treated with SC79 or/and LY294002 at different times and concentrations. The serum ALT, AST, histologic examination, cellular viability, and cell apoptosis were assessed. The levels of phospho-Akt, Bad, Bim, Bax, Bcl-2, and Bcl-XL were determined by Western blot analysis. RESULTS SC79 improved viability and inhibited apoptosis in hepatocytes following H/R. SC79 decreased serum AST and ALT, markedly improved pathology, and decreased cell apoptosis in livers following I/R. In addition, SC79 promoted the expression of phospho-Akt, Bcl-2, and Bcl-XL, and decreased the expression of Bid, Bax, and Bim. PI3K inhibitor (LY294002) pre-treatment completely abolished the above-mentioned effects of SC79. CONCLUSIONS The protective role of SC79 against H/R of hepatocytes or hepatic I/R injury is related to activation of phosphorylation of Akt, resulting in the decrease of pro-apoptotic protein of Bim, Bax, and Bad, and increase of the anti-apoptotic protein Bcl-2 and Bcl-xL induced by cell H/R and hepatic I/R injury.

SC79 protects dopaminergic neurons from oxidative stress

Oxidative stress could lead to dopaminergic neuronal cell death. SC79 is a novel, selective and highly-efficient Akt activator. The current study tested its effect in dopaminergic neurons with oxidative stress. In both SH-SY5Y cells and primary murine dopaminergic neurons, pre-treatment with SC79 largely inhibited hydrogen peroxide (H2O2)-induced cell viability reduction, apoptosis and necrosis. SC79 activated Akt in the neuronal cells, which was required for its neuroprotection against H2O2. Inhibition of Akt activation (by MK-2206 or AT7867) or expression (by targeted short hairpin RNA) largely attenuated SC79-induced neuroprotection. Further, CRISPR-Cas9-mediated Akt1 knockout in SH-SY5Y cells abolished SC79-induced neuroprotective function against H2O2. Reversely, forced activation of Akt by the constitutively-active Akt1 mimicked SC79-induced anti-H2O2 activity. Together, we conclude that activation of Akt by SC79 protects dopaminergic neurons from H2O2.

Targeting sphingosine kinase 2 by ABC294640 inhibits human skin squamous cell carcinoma cell growth

The activity of ABC294640, a small-molecular sphingosine kinase 2 (SphK2) inhibitor, in human skin squamous cell carcinoma (SCC) cells was tested in this study. SphK2 mRNA and protein are expressed in established (A431 cheilocarcinoma cell line) and primary human skin SCC cells. ABC294640 dose-dependently inhibited survival, cell cycle progression and proliferation of skin SCC cells. Furthermore, ABC294640 induced caspase-3/-9 and apoptosis activation in skin SCC cells. The SphK2 inhibitor was however non-cytotoxic to SphK2-null skin melanocytes, keratinocytes and fibroblasts. ABC294640 induced ceramide accumulation, sphingosine-1-phosphate (S1P) reduction, Akt-S6K1 inhibition and JNK activation in skin SCC cells. Conversely, its cytotoxicity against SCC cells was largely attenuated by co-treatment of S1P, the Akt activator SC79, and the JNK inhibitor SP600125. In vivo, ABC294640 oral administration inhibited A431 xenograft tumor growth in nude mice. Akt-S6K1 inhibition and JNK activation were observed in ABC294640-treated tumors. Collectively, ABC294640 efficiently inhibits human skin SCC cell growth in vitro and in vivo.

Akt activation improves microregional oxygen supply/consumption balance after cerebral ischemia-reperfusion

There have been reports that activation of Akt may provide neuroprotection after cerebral ischemia-reperfusion. We tested the hypothesis that activation of Akt would decrease infarct size and improve microregional O₂ supply/consumption balance after cerebral ischemia-reperfusion. This hypothesis was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 h and reperfusion for 2 h with or without SC-79 (Akt activator, 0.05 mg/kg, three doses). Regional cerebral blood flow was determined using a C¹⁴-iodoantipyrine autoradiographic technique. Regional small vessel (20-60 μm diameter) arterial and venous oxygen saturations were determined microspectrophotometrically. Akt phosphorylation was determined by Western blot. There were no significant hemodynamic or blood gas differences between groups. The control ischemic-reperfused cortex had a similar O₂ consumption, but lower blood flow and higher O₂ extraction compared to the contralateral cortex. However, microregional O₂ supply/consumption balance was significantly reduced in the ischemic-reperfused cortex with many areas of low O₂ saturation (42 of 80 veins with O₂ saturation below 50%). SC-79 did not significantly affect cerebral O₂ consumption, but significantly improved O₂ supply/consumption balance in the reperfused area (18 of 80 veins with O₂ saturation below 50%). This was associated with a reduced cortical infarct size (13.3 ± 0.5% control vs 6.7 ± 0.3% SC-79). In control, Akt phosphorylation was elevated at 2 h after ischemia. With SC-79, Akt was activated at 15 min but not at 2 h in the ischemic reperfused area. These results suggest that early Akt activation is important for not only cell survival, but also for the control of local oxygen balance after cerebral ischemia-reperfusion.

Ginseng Rh2 protects endometrial cells from oxygen glucose deprivation/re-oxygenation

In this study, oxygen glucose deprivation/re-oxygenation (OGDR) was applied to cultured endometrial cells to mimic ischemic-reperfusion injuries. We also tested the potential effect of Ginseng Rh2 (GRh2) against the process. In established T-HESC human endometrial cells and primary murine endometrial cells, GRh2 largely inhibited OGDR-induced viability reduction and cell death. Remarkably, OGDR induced programmed necrosis in the endometrial cells, evidenced by cyclophilin D-p53-adenine nucleotide translocator 1 (ANT-1) mitochondrial association, mitochondrial depolarization, reactive oxygen species production, and lactate dehydrogenase release. Notably, such effects by OGDR were largely attenuated with co-treatment of GRh2. Further, cyclophilin D inhibition or knockdown also protected endometrial cells from OGDR. On the other hand, forced over-expression of cyclophilin D facilitated OGDR-induced T-HESC cell necrosis, which was dramatically inhibited by GRh2. Together, GRh2 protects endometrial cells from OGDR possibly via inhibiting CypD-dependent programmed necrosis pathway.

Targeting cyclophilin-D by compound 19 protects neuronal cells from oxygen glucose deprivation/re-oxygenation

Oxygen and glucose deprivation (OGD) with re-oxygenation (OGDR) is applied to neuronal cells to mimic ischemia-reperfusion injuries. Activation of cyclophilin D (Cyp-D)-dependent programmed necrosis pathway mediates OGDR-induced neuronal cell damages. Here, we tested the potential effect of Compound 19 (C19), a novel Cyp-D inhibitor, in this process. In both established neuronal cell lines (Neuro-2a and NB41A3 cells) and the primary murine CA1 hippocampal neurons, pretreatment with C19 largely attenuated OGDR-induced cell viability reduction and cell death. Significantly, C19 was ineffective in Cyp-D-silenced Neuro-2a cells. OGDR induced mitochondria-dependent programmed necrosis in neuronal cells. OGDR induced p53 translocation to mitochondria and association with Cyp-D, causing mitochondrial depolarization, cytochrome C release and reactive oxygen species production. Such effects were largely attenuated with pre-treatment of C19. Importantly, C19 was significantly more efficient than other known Cyp-D inhibitors in protecting neuronal cells from OGDR. These results suggest that targeting Cyp-D by C19 protects neuronal cells from OGDR.

AntagomiR-451 inhibits oxygen glucose deprivation (OGD)-induced HUVEC necrosis via activating AMPK signaling

Oxygen glucose deprivation (OGD) application in cultured human umbilical vein endothelial cells (HUVECs) mimics ischemic injuries. AntagomiR-451, the miroRNA-451 ("miR-451") inhibitor, could activate pro-survival AMP-activated protein kinase (AMPK) signaling. In the current study, we showed that forced-expression of antagomiR-451 depleted miRNA-451 and significantly attenuated OGD-induced necrosis of HUVECs. Activation of AMPK was required for antagomiR-451-mediated pro-survival actions. AMPK inhibition, by AMPKα shRNA or dominant negative mutation, almost completely abolishedantagomiR-451-mediated HUVEC protection again OGD. Reversely, forced-activation of AMPK by exogenous expression of constructively-active AMPKα inhibited OGD-induced HUVEC necrosis. At the molecular level, antagomiR-451 expression in HUVECs inhibited OGD-induced programmed necrosis, the latter was evidenced by mitochondrial p53-cyclophilinD (Cyp-D) association, mitochondrial depolarization as well as reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) breach. Together, we suggest that antagomiR-451 activates AMPK to inhibit OGD-induced programmed necrosis in HUVECs.