Overview of mechanism of electroacupuncture pretreatment for prevention and treatment of cardiovascular and cerebrovascular diseases

Cardio-cerebrovascular disease (CCVD) is a serious threat to huma strategy to prevent the occurrence and development of disease by giving electroacupuncture intervention before the disease occurs. EAP has been shown in many preclinical studies to relieve ischemic symptoms and improve damage from ischemia-reperfusion, with no comprehensive review of its mechanisms in cardiovascular disease yet. In this paper, we first systematically discussed the meridian and acupoint selection law of EAP for CCVD and focused on the progress of the mechanism of action of EAP for the prevention and treatment of CCVD. As a result, in preclinical studies, AMI and MCAO models are commonly used to simulate ischemic injury in CCVD, while MIRI and CI/RI models are used to simulate reperfusion injury caused by blood flow recovery after focal tissue ischemia. According to the meridian matching rules of EAP for CCVD, PC6 in the pericardial meridian is the most commonly used acupoint in cardiovascular diseases, while GV20 in the Du meridian is the most commonly used acupoint in cerebrovascular diseases. In terms of intervention parameters, EAP intervention generally lasts for 30 min, with acupuncture depths mostly between 1.5 and 5 mm, stimulation intensities mostly at 1 mA, and commonly used frequencies being low frequencies. In terms of molecular mechanisms, the key pathways of EAP in preventing and treating cardiovascular and cerebrovascular diseases are partially similar. EAP can play a protective role in cardiovascular and cerebrovascular diseases by promoting autophagy, regulating Ca2+ overload, and promoting vascular regeneration through anti-inflammatory reactions, antioxidant stress, and anti-apoptosis. Of course, both pathways involved have their corresponding specificities. When using EAP to prevent and treat cardiovascular diseases, it involves the metabolic pathway of glutamate, while when using EAP to prevent and treat cerebrovascular diseases, it involves the homeostasis of the blood-brain barrier and the release of neurotransmitters and nutritional factors. I hope these data can provide experimental basis and reference for the clinical promotion and application of EAP in CCVD treatment.

Mitochondrial Kinase Signaling for Cardioprotection

Myocardial ischemia/reperfusion injury is reduced by cardioprotective adaptations such as local or remote ischemic conditioning. The cardioprotective stimuli activate signaling cascades, which converge on mitochondria and maintain the function of the organelles, which is critical for cell survival. The signaling cascades include not only extracellular molecules that activate sarcolemmal receptor-dependent or -independent protein kinases that signal at the plasma membrane or in the cytosol, but also involve kinases, which are located to or within mitochondria, phosphorylate mitochondrial target proteins, and thereby modify, e.g., respiration, the generation of reactive oxygen species, calcium handling, mitochondrial dynamics, mitophagy, or apoptosis. In the present review, we give a personal and opinionated overview of selected protein kinases, localized to/within myocardial mitochondria, and summarize the available data on their role in myocardial ischemia/reperfusion injury and protection from it. We highlight the regulation of mitochondrial function by these mitochondrial protein kinases.

Ischemia-reperfusion injury: molecular mechanisms and therapeutic targets

Ischemia-reperfusion (I/R) injury paradoxically occurs during reperfusion following ischemia, exacerbating the initial tissue damage. The limited understanding of the intricate mechanisms underlying I/R injury hinders the development of effective therapeutic interventions. The Wnt signaling pathway exhibits extensive crosstalk with various other pathways, forming a network system of signaling pathways involved in I/R injury. This review article elucidates the underlying mechanisms involved in Wnt signaling, as well as the complex interplay between Wnt and other pathways, including Notch, phosphatidylinositol 3-kinase/protein kinase B, transforming growth factor-β, nuclear factor kappa, bone morphogenetic protein, N-methyl-D-aspartic acid receptor-Ca2+-Activin A, Hippo-Yes-associated protein, toll-like receptor 4/toll-interleukine-1 receptor domain-containing adapter-inducing interferon-β, and hepatocyte growth factor/mesenchymal-epithelial transition factor. In particular, we delve into their respective contributions to key pathological processes, including apoptosis, the inflammatory response, oxidative stress, extracellular matrix remodeling, angiogenesis, cell hypertrophy, fibrosis, ferroptosis, neurogenesis, and blood-brain barrier damage during I/R injury. Our comprehensive analysis of the mechanisms involved in Wnt signaling during I/R reveals that activation of the canonical Wnt pathway promotes organ recovery, while activation of the non-canonical Wnt pathways exacerbates injury. Moreover, we explore novel therapeutic approaches based on these mechanistic findings, incorporating evidence from animal experiments, current standards, and clinical trials. The objective of this review is to provide deeper insights into the roles of Wnt and its crosstalk signaling pathways in I/R-mediated processes and organ dysfunction, to facilitate the development of innovative therapeutic agents for I/R injury.

Ehrlichia effector SLiM-icry: Artifice of cellular subversion

As an obligately intracellular bacterial pathogen that selectively infects the mononuclear phagocyte, Ehrlichia chaffeensis has evolved sophisticated mechanisms to subvert innate immune defenses. While the bacterium accomplishes this through a variety of mechanisms, a rapidly expanding body of evidence has revealed that E. chaffeensis has evolved survival strategies that are directed by the versatile, intrinsically disordered, 120 kDa tandem repeat protein (TRP120) effector. E. chaffeensis establishes infection by manipulating multiple evolutionarily conserved cellular signaling pathways through effector-host interactions to subvert innate immune defenses. TRP120 activates these pathways using multiple functionally distinct, repetitive, eukaryote-mimicking short linear motifs (SLiMs) located within the tandem repeat domain that have evolved in nihilo. Functionally, the best characterized TRP120 SLiMs mimic eukaryotic ligands (SLiM-icry) to engage pathway-specific host receptors and activate cellular signaling, thereby repurposing these pathways to promote infection. Moreover, E. chaffeensis TRP120 contains SLiMs that are targets of post-translational modifications such as SUMOylation in addition to many other validated SLiMs that are curated in the eukaryotic linear motif (ELM) database. This review will explore the extracellular and intracellular roles TRP120 SLiM-icry plays during infection - mediated through a variety of SLiMs - that enable E. chaffeensis to subvert mononuclear phagocyte innate defenses.

Modeling incomplete penetrance in arrhythmogenic cardiomyopathy by human induced pluripotent stem cell derived cardiomyocytes

Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) are commonly used to model arrhythmogenic cardiomyopathy (ACM), a heritable cardiac disease characterized by severe ventricular arrhythmias, fibrofatty myocardial replacement and progressive ventricular dysfunction. Although ACM is inherited as an autosomal dominant disease, incomplete penetrance and variable expressivity are extremely common, resulting in different clinical manifestations. Here, we propose hiPSC-CMs as a powerful in vitro model to study incomplete penetrance in ACM. Six hiPSC lines were generated from blood samples of three ACM patients carrying a heterozygous deletion of exon 4 in the PKP2 gene, two asymptomatic (ASY) carriers of the same mutation and one healthy control (CTR), all belonging to the same family. Whole exome sequencing was performed in all family members and hiPSC-CMs were examined by ddPCR, western blot, Wes™ immunoassay system, patch clamp, immunofluorescence and RNASeq. Our results show molecular and functional differences between ACM and ASY hiPSC-CMs, including a higher amount of mutated PKP2 mRNA, a lower expression of the connexin-43 protein, a lower overall density of sodium current, a higher intracellular lipid accumulation and sarcomere disorganization in ACM compared to ASY hiPSC-CMs. Differentially expressed genes were also found, supporting a predisposition for a fatty phenotype in ACM hiPSC-CMs. These data indicate that hiPSC-CMs are a suitable model to study incomplete penetrance in ACM.

The role of β-catenin in cardiac diseases

The Wnt/β-catenin signaling pathway is a classical Wnt pathway that regulates the stability and nuclear localization of β-catenin and plays an important role in adult heart development and cardiac tissue homeostasis. In recent years, an increasing number of researchers have implicated the dysregulation of this signaling pathway in a variety of cardiac diseases, such as myocardial infarction, arrhythmias, arrhythmogenic cardiomyopathy, diabetic cardiomyopathies, and myocardial hypertrophy. The morbidity and mortality of cardiac diseases are increasing, which brings great challenges to clinical treatment and seriously affects patient health. Thus, understanding the biological roles of the Wnt/β-catenin pathway in these diseases may be essential for cardiac disease treatment and diagnosis to improve patient quality of life. In this review, we summarize current research on the roles of β-catenin in human cardiac diseases and potential inhibitors of Wnt/β-catenin, which may provide new strategies for cardiac disease therapies.

ROS-Influenced Regulatory Cross-Talk With Wnt Signaling Pathway During Perinatal Development

Over a century ago, it was found that a rapid burst of oxygen is needed and produced by the sea urchin oocyte to activate fertilization and block polyspermy. Since then, scientific research has taken strides to establish that Reactive Oxygen Species (ROS), besides being toxic effectors of cellular damage and death, also act as molecular messengers in important developmental signaling cascades, thereby modulating them. Wnt signaling pathway is one such developmental pathway, which has significant effects on growth, proliferation, and differentiation of cells at the earliest embryonic stages of an organism, apart from being significant role-players in the instances of cellular transformation and cancer when this tightly-regulated system encounters aberrations. In this review, we discuss more about the Wnt and ROS signaling pathways, how they function, what roles they play overall in animals, and mostly about how these two major signaling systems cross paths and interplay in mediating major cellular signals and executing the predestined changes during the perinatal condition, in a systematic manner.

Therapeutic effect of adipose stromal vascular fraction spheroids for partial bladder outlet obstruction induced underactive bladder

BACKGROUND

Underactive bladder (UAB) is a common clinical problem but related research is rarely explored. As there are currently no effective therapies, the administration of adipose stromal vascular fraction (ad-SVF) provides a new potential method to treat underactive bladder.

METHODS

Male Sprague-Dawley rats were induced by partial bladder outlet obstruction (PBOO) for four weeks and randomly divided into three groups: rats treated with PBS (Sham group); rats administrated with ad-SVF (ad-SVF group) and rats performed with ad-SVF spheroids (ad-SVFsp group). After four weeks, urodynamic studies were performed to evaluate bladder functions and all rats were sacrificed for further studies.

RESULTS

We observed that the bladder functions and symptoms of UAB were significantly improved in the ad-SVFsp group than that in the Sham group and ad-SVF group. Meanwhile, our data showed that ad-SVF spheroids could remarkably promote angiogenesis, suppress cell apoptosis and stimulate cell proliferation in bladder tissue than that in the other two groups. Moreover, ad-SVF spheroids increased the expression levels of bFGF, HGF and VEGF-A than ad-SVF. IVIS Spectrum small-animal in vivo imaging system revealed that ad-SVF spheroids could increase the retention rate of transplanted cells in bladder tissue.

CONCLUSIONS

Ad-SVF spheroids improved functions and symptoms of bladder induced by PBOO, which contributes to promote angiogenesis, suppress cell apoptosis and stimulate cell proliferation. Ad-SVF spheroids provide a potential treatment for the future patients with UAB.

Rigosertib elicits potent anti-tumor responses in colorectal cancer by inhibiting Ras signaling pathway

BACKGROUND

The therapeutic potency of Rigosertib (RGS) in the treatment of the myelodysplastic syndrome has been investigated previously, but little is known about its mechanisms of action.

METHODS

The present study integrates systems and molecular biology approaches to investigate the mechanisms of the anti-tumor effects of RGS, either alone or in combination with 5-FU in cellular and animal models of colorectal cancer (CRC).

RESULTS

The effects of RGS were more pronounced in dedifferentiated CRC cell types, compared to cell types that were epithelial-like. RGS inhibited cell proliferation and cell cycle progression in a cell-type specific manner, and that was dependent on the presence of mutations in KRAS, or its down-stream effectors. RGS increased both early and late apoptosis, by regulating the expression of p53, BAX and MDM2 in tumor model. We also found that RGS induced cell senescence in tumor tissues by increasing ROS generation, and impairing oxidant/anti-oxidant balance. RGS also inhibited angiogenesis and metastatic behavior of CRC cells, by regulating the expression of CD31, E-cadherin, and matrix metalloproteinases-2 and 9.

CONCLUSION

Our findings support the therapeutic potential of this potent RAS signaling inhibitor either alone or in combination with standard regimens for the management of patients with CRC.

The Redox Modulating Sonlicromanol Active Metabolite KH176m and the Antioxidant MPG Protect Against Short-Duration Cardiac Ischemia-Reperfusion Injury

Purpose

Sonlicromanol is a phase IIB clinical stage compound developed for treatment of mitochondrial diseases. Its active component, KH176m, functions as an antioxidant, directly scavenging reactive oxygen species (ROS), and redox activator, boosting the peroxiredoxin-thioredoxin system. Here, we examined KH176m’s potential to protect against acute cardiac ischemia-reperfusion injury (IRI), compare it with the classic antioxidant N-(2-mercaptopropionyl)-glycine (MPG), and determine whether protection depends on duration (severity) of ischemia.

Methods

Isolated C56Bl/6N mouse hearts were Langendorff-perfused and subjected to short (20 min) or long (30 min) ischemia, followed by reperfusion. During perfusion, hearts were treated with saline, 10 μM KH176m, or 1 mM MPG. Cardiac function, cell death (necrosis), and mitochondrial damage (cytochrome c (CytC) release) were evaluated. In additional series, the effect of KH176m treatment on the irreversible oxidative stress marker 4-hydroxy-2-nonenal (4-HNE), formed during ischemia only, was determined at 30-min reperfusion.

Results

During baseline conditions, both drugs reduced cardiac performance, with opposing effects on vascular resistance (increased with KH176m, decreased with MPG). For short ischemia, KH176m robustly reduced all cell death parameters: LDH release (0.2 ± 0.2 vs 0.8 ± 0.5 U/min/GWW), infarct size (15 ± 8 vs 31 ± 20%), and CytC release (168.0 ± 151.9 vs 790.8 ± 453.6 ng/min/GWW). Protection by KH176m was associated with decreased cardiac 4-HNE. MPG only reduced CytC release. Following long ischemia, IRI was doubled, and KH176m and MPG now only reduced LDH release. The reduced protection against long ischemia was associated with the inability to reduce cardiac 4-HNE.

Conclusion

Protection against cardiac IRI by the antioxidant KH176m is critically dependent on duration of ischemia. The data suggest that with longer ischemia, the capacity of KH176m to reduce cardiac oxidative stress is rate-limiting, irreversible ischemic oxidative damage maximally accumulates, and antioxidant protection is strongly diminished.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10557-021-07189-9.

Anaplasmataceae: Dichotomous Autophagic Interplay for Infection

Autophagy is a vital conserved degradative process that maintains cellular homeostasis by recycling or eliminating dysfunctional cellular organelles and proteins. More recently, autophagy has become a well-recognized host defense mechanism against intracellular pathogens through a process known as xenophagy. On the host-microbe battlefield many intracellular bacterial pathogens have developed the ability to subvert xenophagy to establish infection. Obligately intracellular bacterial pathogens of the Anaplasmataceae family, including Ehrlichia chaffeensis, Anaplasma phaogocytophilium and Orientia tsutsugamushi have developed a dichotomous strategy to exploit the host autophagic pathway to obtain nutrients while escaping lysosomal destruction for intracellular survival within the host cell. In this review, the recent findings regarding how these master manipulators engage and inhibit autophagy for infection are explored. Future investigation to understand mechanisms used by Anaplasmataceae to exploit autophagy may advance novel antimicrobial therapies and provide new insights into how intracellular microbes exploit autophagy to survive.

Immune, inflammatory, autophagic and DNA damage responses to long-term H2O2 exposure in different tissues of common carp (Cyprinus carpio)

Hydrogen peroxide (H₂O₂) is a stable reactive oxygen species (ROS) in aquatic environment, and high concentration of ambient H₂O₂ may directly or indirectly affect aquatic animal health. However, the response mechanism of fish to ambient H₂O₂ has not been well studied yet. Therefore, the aim of the study was to investigate the immune, inflammatory, autophagic and DNA damage responses to long-term H₂O₂ exposure in different tissues of common carp. The results showed that H₂O₂ exposure induced a significant immune response, with alterations in the levels of immune parameters including AKP, ACP, LZM, C3, HSP90 and HSP70 in different tissues. The inflammatory response evoked by H₂O₂ exposure was associated with the activations of TLRs and NF-κB (P65) in the majority of tested tissues. The autophagy process was significantly affected by H₂O₂ exposure, evidenced by the upregulations of the autophagy-related genes in liver, gills, muscle, intestines, heart and spleen and the downregulations in kidney. Meanwhile, the mRNA level of atm, a primary transducer of DNA damage response, was upregulated in liver, gills, intestines and spleen, and the DNA damage was evidenced by increased 8-OHdG level in intestines after H₂O₂ exposure. Moreover, cell cycle regulation-related genes, including cyclin A1, B and/or E1, highly expressed in all tested tissues except heart after H₂O₂ exposure. Interestingly, IBR analysis exhibited that immune, inflammatory, autophagic and DNA damage responses to H₂O₂ exposure were in a dose-dependent and tissue-specific manner. These data may contribute to understanding H₂O₂ toxicity for fish and assessing potential risk of H₂O₂ in aquatic environment.

Secreted frizzled protein 3 is a novel cardioprotective mechanism unique to the clinically relevant fourth window of ischemic preconditioning

Most studies on ischemic preconditioning (IPC) use one or two ischemic stimuli before examining cardioprotection. To better simulate the clinical situation, we examined, in pigs, the effects of six episodes of 10 min coronary artery occlusion (CAO) 12 h apart, followed by 60 min CAO. We named this model the fourth window of IPC. To determine the novel mechanisms mediating cardioprotection in the fourth window, gene analysis was examined in fourth window IPC cardiac tissue 60 min after the last episode of 10 min CAO. Secreted frizzled-related protein 3 (sFRP3) was the most significantly upregulated gene that was unique to the fourth window, that is, not found in the first, second, or third window IPC. To study the effects of sFRP3 on cardioprotection, sFRP3 was injected in the hearts of wild-type (WT) mice. In the [CAO/coronary artery reperfusion (CAR)] model (30 min CAO followed by 24 h CAR), infarct size was less, P < 0.01, after sFRP3 injection (14% ± 1.7%) compared with vehicle injection (48% ± 1.6%). sFRP3 injection also protected the development of heart failure following permanent CAO for 2 wk. Left ventricular ejection fraction was significantly improved, P < 0.05, at 2 wk after CAO with sFRP3 (53% ± 5%) compared with vehicle (36% ± 2%) and was accompanied by significant, P < 0.01, reductions in myocardial fibrosis (53% ± 4%), myocyte size (17% ± 3%), apoptosis (100%), and mortality (56%). Thus, sFRP3, unique to the clinically relevant fourth window IPC model, is a novel mechanism mediating ischemic cardioprotection.NEW & NOTEWORTHY1) This investigation identifies the novel fourth window of ischemic preconditioning. 2) sFRP3 was identified as the most significantly upregulated gene in the fourth window and was shown to induce cardioprotection when administered to the hearts of wild-type mice.

The Role of Oxidative Stress in Cardiovascular Aging and Cardiovascular Diseases

Aging can be seen as process characterized by accumulation of oxidative stress induced damage. Oxidative stress derives from different endogenous and exogenous processes, all of which ultimately lead to progressive loss in tissue and organ structure and functions. The oxidative stress theory of aging expresses itself in age-related diseases. Aging is in fact a primary risk factor for many diseases and in particular for cardiovascular diseases and its derived morbidity and mortality. Here we highlight the role of oxidative stress in age-related cardiovascular aging and diseases. We take into consideration the molecular mechanisms, the structural and functional alterations, and the diseases accompanied to the cardiovascular aging process.

MTORC1-Regulated Metabolism Controlled by TSC2 Limits Cardiac Reperfusion Injury

RATIONALE

The mTORC1 (mechanistic target of rapamycin complex-1) controls metabolism and protein homeostasis and is activated following ischemia reperfusion (IR) injury and by ischemic preconditioning (IPC). However, studies vary as to whether this activation is beneficial or detrimental, and its influence on metabolism after IR is little reported. A limitation of prior investigations is their use of broad gain/loss of mTORC1 function, mostly applied before ischemic stress. This can be circumvented by regulating one serine (S1365) on TSC2 (tuberous sclerosis complex) to achieve bidirectional mTORC1 modulation but only with TCS2-regulated costimulation.

OBJECTIVE

We tested the hypothesis that reduced TSC2 S1365 phosphorylation protects the myocardium against IR and is required for IPC by amplifying mTORC1 activity to favor glycolytic metabolism.

METHODS AND RESULTS

Mice with either S1365A (TSC2^SA; phospho-null) or S1365E (TSC2^SE; phosphomimetic) knockin mutations were studied ex vivo and in vivo. In response to IR, hearts from TSC2^SA mice had amplified mTORC1 activation and improved heart function compared with wild-type and TSC2^SE hearts. The magnitude of protection matched IPC. IPC requited less S1365 phosphorylation, as TSC2^SE hearts gained no benefit and failed to activate mTORC1 with IPC. IR metabolism was altered in TSC2^SA, with increased mitochondrial oxygen consumption rate and glycolytic capacity (stressed/maximal extracellular acidification) after myocyte hypoxia-reperfusion. In whole heart, lactate increased and long-chain acylcarnitine levels declined during ischemia. The relative IR protection in TSC2^SA was lost by lowering glucose in the perfusate by 36%. Adding fatty acid (palmitate) compensated for reduced glucose in wild type and TSC2^SE but not TSC2^SA which had the worst post-IR function under these conditions.

CONCLUSIONS

TSC2-S1365 phosphorylation status regulates myocardial substrate utilization, and its decline activates mTORC1 biasing metabolism away from fatty acid oxidation to glycolysis to confer protection against IR. This pathway is also engaged and reduced TSC2 S1365 phosphorylation required for effective IPC. Graphic Abstract: A graphic abstract is available for this article.

Perioperative Cardioprotection: General Mechanisms and Pharmacological Approaches

Cardioprotection encompasses a variety of strategies protecting the heart against myocardial injury that occurs during and after inadequate blood supply to the heart during myocardial infarction. While restoring reperfusion is crucial for salvaging myocardium from further damage, paradoxically, it itself accounts for additional cell death-a phenomenon named ischemia/reperfusion injury. Therefore, therapeutic strategies are necessary to render the heart protected against myocardial infarction. Ischemic pre- and postconditioning, by short periods of sublethal cardiac ischemia and reperfusion, are still the strongest mechanisms to achieve cardioprotection. However, it is highly impractical and far too invasive for clinical use. Fortunately, it can be mimicked pharmacologically, for example, by volatile anesthetics, noble gases, opioids, propofol, dexmedetomidine, and phosphodiesterase inhibitors. These substances are all routinely used in the clinical setting and seem promising candidates for successful translation of cardioprotection from experimental protocols to clinical trials. This review presents the fundamental mechanisms of conditioning strategies and provides an overview of the most recent and relevant findings on different concepts achieving cardioprotection in the experimental setting, specifically emphasizing pharmacological approaches in the perioperative context.

Glycogen synthase kinase 3β in tumorigenesis and oncotherapy (Review)

Glycogen synthase kinase 3β (GSK 3β), a multifunctional serine and threonine kinase, plays a critical role in a variety of cellular activities, including signaling transduction, protein and glycogen metabolism, cell proliferation, cell differentiation, and apoptosis. Therefore, aberrant regulation of GSK 3β results in a broad range of human diseases, such as tumors, diabetes, inflammation and neurodegenerative diseases. Accumulating evidence has suggested that GSK 3β is correlated with tumorigenesis and progression. However, GSK 3β is controversial due to its bifacial roles of tumor suppression and activation. In addition, overexpression of GSK 3β is involved in tumor growth, whereas it contributes to the cell sensitivity to chemotherapy. However, the underlying regulatory mechanisms of GSK 3β in tumorigenesis remain obscure and require further in‑depth investigation. In this review, we comprehensively summarize the roles of GSK 3β in tumorigenesis and oncotherapy, and focus on its potentials as an available target in oncotherapy.

PKG1α Cysteine-42 Redox State Controls mTORC1 Activation in Pathological Cardiac Hypertrophy

RATIONALE

Stimulated PKG1α (protein kinase G-1α) phosphorylates TSC2 (tuberous sclerosis complex 2) at serine 1365, potently suppressing mTORC1 (mechanistic [mammalian] target of rapamycin complex 1) activation by neurohormonal and hemodynamic stress. This reduces pathological hypertrophy and dysfunction and increases autophagy. PKG1α oxidation at cysteine-42 is also induced by these stressors, which blunts its cardioprotective effects.

OBJECTIVE

We tested the dependence of mTORC1 activation on PKG1α C42 oxidation and its capacity to suppress such activation by soluble GC-1 (guanylyl cyclase 1) activation.

METHODS AND RESULTS

Cardiomyocytes expressing wild-type (WT) PKG1α (PKG1αWT) or cysteine-42 to serine mutation redox-dead (PKG1αCS/CS) were exposed to ET-1 (endothelin 1). Cells expressing PKG1αWT exhibited substantial mTORC1 activation (p70 S6K [p70 S6 kinase], 4EBP1 [elF4E binding protein-1], and Ulk1 [Unc-51-like kinase 1] phosphorylation), reduced autophagy/autophagic flux, and abnormal protein aggregation; all were markedly reversed by PKG1αCS/CS expression. Mice with global knock-in of PKG1αCS/CS subjected to pressure overload (PO) also displayed markedly reduced mTORC1 activation, protein aggregation, hypertrophy, and ventricular dysfunction versus PO in PKG1αWT mice. Cardioprotection against PO was equalized between groups by co-treatment with the mTORC1 inhibitor everolimus. TSC2-S1365 phosphorylation increased in PKG1αCS/CS more than PKG1αWT myocardium following PO. TSC2S1365A/S1365A (TSC2 S1365 phospho-null, created by a serine to alanine mutation) knock-in mice lack TSC2 phosphorylation by PKG1α, and when genetically crossed with PKG1αCS/CS mice, protection against PO-induced mTORC1 activation, cardiodepression, and mortality in PKG1αCS/CS mice was lost. Direct stimulation of GC-1 (BAY-602770) offset disparate mTORC1 activation between PKG1αWT and PKG1αCS/CS after PO and blocked ET-1 stimulated mTORC1 in TSC2S1365A-expressing myocytes.

CONCLUSIONS

Oxidation of PKG1α at C42 reduces its phosphorylation of TSC2, resulting in amplified PO-stimulated mTORC1 activity and associated hypertrophy, dysfunction, and depressed autophagy. This is ameliorated by direct GC-1 stimulation.

Isoform- and Cell Type-Specific Roles of Glycogen Synthase Kinase 3 N-Terminal Serine Phosphorylation in Liver Ischemia Reperfusion Injury

Glycogen synthase kinase 3 (Gsk3) α and β are both constitutively active and inhibited upon stimulation by N-terminal serine phosphorylation. Although roles of active Gsk3 in liver ischemia reperfusion injury (IRI) have been well appreciated, whether Gsk3 N-terminal serine phosphorylation has any functional significance in the disease process remains unclear. In a murine liver partial warm ischemia model, we studied Gsk3 N-terminal serine mutant knock-in (KI) mice and showed that liver IRI was decreased in Gsk3αS21A but increased in Gsk3βS9A mutant KI mice. Bone marrow chimeric experiments revealed that the Gsk3α, but not β, mutation in liver parenchyma protected from IRI, and both mutations in bone marrow-derived cells exacerbated liver injuries. Mechanistically, mutant Gsk3α protected hepatocytes from inflammatory (TNF-α) cell death by the activation of HIV-1 TAT-interactive protein 60 (TIP60)-mediated autophagy pathway. The pharmacological inhibition of TIP60 or autophagy diminished the protection of the Gsk3α mutant hepatocytes from inflammatory cell death in vitro and the Gsk3α mutant KI mice from liver IRI in vivo. Thus, Gsk3 N-terminal serine phosphorylation inhibits liver innate immune activation but suppresses hepatocyte autophagy in response to inflammation. Gsk3 αS21, but not βS9, mutation is sufficient to sustain Gsk4 activities in hepatocytes and protect livers from IRI via TIP60 activation.

Bisoprolol, a β1 antagonist, protects myocardial cells from ischemia-reperfusion injury via PI3K/AKT/GSK3β pathway

The aim of this work was to explore whether bisoprolol plays a protective role in cardiomyocytes against ischemia-reperfusion injury via PI3K/AKT/ GSK3β pathway. We pretreated male Sprague Dawley (SD) rats with bisoprolol by oral administration prior to 0.5 h ischemia/4 h reperfusion. Myocardial infarct size and serum levels of cTnI and CK-MB were measured. In vitro, H9c2 cells were treated with hypoxia and reoxygenation, followed by measurement of cell viability, apoptosis, ROS production, cytometry, activities of AKT, GSK3β, and p-38 in the presence and absence of GSK3β siRNA. We found that bisoprolol reduced infarct size from 44% in I/R group to 31% in treated group (P < 0.05). The levels of cTnI and CK-MB were decreased from 286 ± 7 pg/mL and 32.2 ± 2 ng/mL in I/R group to 196 ± 2 pg/mL and 19.6 ± 0.9 ng/mL in the treated group, respectively (P < 0.05). Bisoprolol also increased cell viability while decreased apoptosis and ROS production in the treatment of hypoxia/ reoxygenation. Furthermore, bisoprolol increased AKT and GSK3β phosphorylation, an effect that was immediately eliminated by LY294002. GSK3β-specific siRNA experiment further confirmed that bisoprolol protected the myocardium against hypoxia/reoxygenation-induced injury via suppressing GSK3β activity. In conclusion, bisoprolol protected myocardium against ischemia-reperfusion injury via the PI3K/AKT/ GSK3β pathway.

Cardioprotection in right heart failure

Ischaemic and pharmacological conditioning of the left ventricle is mediated by the activation of signalling cascades, which finally converge at the mitochondria and reduce ischaemia/reperfusion (I/R) injury. Whereas the molecular mechanisms of conditioning in the left ventricle are well characterized, cardioprotection of the right ventricle is principally feasible but less established. Similar to what is known for the left ventricle, a dysregulation in signalling pathways seems to play a role in I/R injury of the healthy and failing right ventricle and in the ability/inability of the right ventricle to respond to a conditioning stimulus. The maintenance of mitochondrial function seems to be crucial in both ventricles to reduce I/R injury. As far as currently known, similar molecular mechanisms mediate ischaemic and pharmacological preconditioning in the left and right ventricles. However, the two ventricles seem to respond differently towards exercise‐induced preconditioning.

LINKED ARTICLES

This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc

High ratio of ω-3/ω-6 polyunsaturated fatty acids targets mTORC1 to prevent high-fat diet-induced metabolic syndrome and mitochondrial dysfunction in mice

Adjusting ω-3/ω-6 polyunsaturated fatty acids (PUFAs) ratio in high-fat diet is one potential mean to improve metabolic syndrome; however, underlying mechanisms remain unclear. Four groups of mice were fed 60% kcal diets with saturated fatty acids, three different ω-3/ω-6 PUFAs ratios (low, middle and high) for 12 weeks, respectively. Body weight, atherosclerosis marker, insulin signal index and level of lipid accumulation in liver were significantly lowered in High group compared with saturated fatty acids group and Low group at week 12. Expressions of p-mTOR and raptor were inhibited by high ω-3 PUFAs. Importantly, ω-3 PUFAs intake up-regulated mitochondrial electron transport chain and tricarboxylic acid cycle pathway through metabolomics analysis in liver. Mitochondrial complexes activities were raised, fumaric acid was reduced and oxidative stress was alleviated in High group. We conclude that consuming long-term high-fat diet with same calories but high ω-3/ω-6 PUFAs ratio relieves metabolic syndrome by regulating mTORC1 pathway to enhance mitochondrial function.

Investigating and re-evaluating the role of glycogen synthase kinase 3 beta kinase as a molecular target for cardioprotection by using novel pharmacological inhibitors

AIMS

Glycogen synthase kinase 3 beta (GSK3β) link with the mitochondrial Permeability Transition Pore (mPTP) in cardioprotection is debated. We investigated the role of GSK3β in ischaemia (I)/reperfusion (R) injury using pharmacological tools.

METHODS AND RESULTS

Infarct size using the GSK3β inhibitor BIO (6-bromoindirubin-3'-oxime) and several novel analogues (MLS2776-MLS2779) was determined in anaesthetized rabbits and mice. In myocardial tissue GSK3β inhibition and the specificity of the compounds was tested. The mechanism of protection focused on autophagy-related proteins. GSK3β localization was determined in subsarcolemmal (SSM) and interfibrillar mitochondria (IFM) isolated from Langendorff-perfused murine hearts (30'I/10'R or normoxic conditions). Calcium retention capacity (CRC) was determined in mitochondria after administration of the inhibitors in mice and in vitro. The effects of the inhibitors on mitochondrial respiration, reactive oxygen species (ROS) formation, ATP production, or hydrolysis were measured in SSM at baseline. Cyclosporine A (CsA) was co-administered with the inhibitors to address putative additive cardioprotective effects. Rabbits and mice treated with MLS compounds had smaller infarct size compared with control. In rabbits, MLS2776 and MLS2778 possessed greater infarct-sparing effects than BIO. GSK3β inhibition was confirmed at the 10th min and 2 h of reperfusion, while up-regulation of autophagy-related proteins was evident at late reperfusion. The mitochondrial amount of GSK3β was similar in normoxic SSM and IFM and was not altered by I/R. The inhibitors did not affect CRC or respiration, ROS and ATP production/hydrolysis at baseline. The co-administration of CsA ensured that cardioprotection was CypD-independent.

CONCLUSION

Pharmacological inhibition of GSK3β attenuates infarct size beyond mPTP inhibition.

Reciprocal regulation of TORC signaling and tRNA modifications by Elongator enforces nutrient-dependent cell fate

Nutrient availability has a profound impact on cell fate. Upon nitrogen starvation, wild-type fission yeast cells uncouple cell growth from cell division to generate small, round-shaped cells that are competent for sexual differentiation. The TORC1 (TOR complex 1) and TORC2 complexes exert opposite controls on cell growth and cell differentiation, but little is known about how their activity is coordinated. We show that transfer RNA (tRNA) modifications by Elongator are critical for this regulation by promoting the translation of both key components of TORC2 and repressors of TORC1. We further identified the TORC2 pathway as an activator of Elongator by down-regulating a Gsk3 (glycogen synthase kinase 3)-dependent inhibitory phosphorylation of Elongator. Therefore, a feedback control is operating between TOR complex (TORC) signaling and tRNA modification by Elongator to enforce the advancement of mitosis that precedes cell differentiation.

Hypoxic postconditioning activates the Wnt/β-catenin pathway and protects against transient global cerebral ischemia through Dkk1 Inhibition and GSK-3β inactivation

The Wingless/Int (Wnt)/β-catenin pathway plays an essential role in cell survival. Although postconditioning with 8% oxygen can alleviate transient global cerebral ischemia (tGCI)-induced neuronal damage in hippocampal CA1 subregion in adult rats as demonstrated by our previous studies, little is understood about the role of Wnt/β-catenin pathway in hypoxic postconditioning (HPC)-induced neuroprotection. This study tried to investigate the involvement of Wnt/β-catenin pathway in HPC-induced neuroprotection against tGCI and explore the underlying molecular mechanism thereof. We observed that HPC elevated nuclear β-catenin level as well as increased Wnt3a and decreased Dickkopf-1 (Dkk1) expression in CA1 after tGCI. Accordingly, HPC enhanced the expression of survivin and reduced the ratio of B-cell lymphoma/lewkmia-2 (Bcl-2)-associated X protein (Bax) to Bcl-2 following reperfusion. Moreover, our study has shown that these effects of HPC were abolished by lentivirus-mediated overexpression of Dkk1, and that the overexpression of Dkk1 completely reversed HPC-induced neuroprotection. Furthermore, HPC suppressed the activity of glycogen synthase kinase-3β (GSK-3β) in CA1 after tGCI, and the inhibition of GSK-3β activity with SB216763 increased the nuclear accumulation of β-catenin, up-regulated the expression of survivin, and reduced the ratio of Bax to Bcl-2, thus preventing the delayed neuronal death after tGCI. Finally, the administration of LY294002, an inhibitor of PI3K, increased GSK-3β activity and blocked nuclear β-catenin accumulation, thereby decreasing survivin expression and elevating the Bax-to-Bcl-2 ratio after HPC. These results suggest that activation of the Wnt/β-catenin pathway through Dkk1 inhibition and PI3K/protein kinase B pathway-mediated GSK-3β inactivation contributes to the neuroprotection of HPC against tGCI.-Zhan, L., Liu, D., Wen, H., Hu, J., Pang, T., Sun, W., Xu, E. Hypoxic postconditioning activates the Wnt/β-catenin pathway and protects against transient global cerebral ischemia through Dkk1 inhibition and GSK-3β inactivation.

Alteration of the Wnt/GSK3β/β‑catenin signalling pathway by rapamycin ameliorates pathology in an Alzheimer's disease model

The abnormal activation of glycogen synthase kinase 3β (GSK3β) is one of the mechanisms involved in the pathogenesis of Alzheimer's disease (AD), which results in amyloid β‑peptide (Aβ) plaque overproduction, Tau hyperphosphorylation and neuronal loss. A number of studies have reported that the activation of the mammalian target of rapamycin (mTOR) contributes to the generation and deposition of Aβ, as well as to the formation of neurofibrillary tangles (NFTs) by inhibiting autophagy. GSK3β is also involved in the mTOR signalling pathway. However, whether the inhibition of the activation of mTOR via the regulation of the function of GSK3β affects the pathology of AD remains unclear. In this study, we intraperitoneally injected amyloid precursor protein (APP)/presenilin‑1 (PS1) transgenic mice with rapamycin, a known activator of autophagy that inhibits mTOR. Our results revealed that rapamycin treatment decreased senile plaque deposition by reducing APP generation, and downregulating β‑ and γ‑secretase activity. Rapamycin also increased Aβ clearance by promoting autophagy and reduced Tau hyperphosphorylation by upregulating the levels of insulin‑degrading enzyme. Additionally, rapamycin markedly promoted the proliferation of differentiated SH‑SY5Y cells stably transfected with the APPswe gene and prevented neuronal loss in the brains of mice in a model of AD. Moreover, rapamycin induced autophagy and promoted autolysosome degradation. In this study, we provide evidence that rapamycin inhibits GSK3β activation and elevates β‑catenin expression by improving the Wnt3a expression levels, which facilitates the amelioration of AD pathology. On the whole, our findings indicate that rapamycin inhibits the activation of mTOR and alters the Wnt/GSK3β/β‑catenin signalling pathway; thus, it may serve as a therapeutic target in the treatment of AD.

Milrinone-Induced Pharmacological Preconditioning in Cardioprotection: Hints for a Role of Mitochondrial Mechanisms

The activation of mitochondrial calcium-sensitive potassium (mBK_Ca) channels is crucially involved in cardioprotection induced by preconditioning. For milrinone (Mil)-induced preconditioning, the involvement of mBK_Ca-channels and further mitochondrial signaling is unknown. We hypothesize that (1) Mil-induced preconditioning is concentration-dependent and (2) that the activation of mBK_Ca-channels, release of reactive oxygen species (ROS), and the mitochondrial permeability transition pore (mPTP) could be involved. Isolated hearts of male Wistar rats were perfused with Krebs-Henseleit buffer and underwent 33 min of ischemia followed by 60 min of reperfusion. For determination of a concentration-dependent effect of Mil, hearts were perfused with different concentrations of Mil (0.3–10 µM) over 10 min before ischemia. In a second set of experiments, in addition to controls, hearts were pretreated with the lowest protective concentration of 1 µM Mil either alone or combined with the mBK_Ca-channel blocker paxilline (Pax + Mil), or paxilline alone (Pax). In additional groups, Mil was administered with and without the ROS scavenger N-2-mercaptopropionylglycine (MPG + Mil, MPG) or the mPTP inhibitor cyclosporine A (MPG + Mil + CsA, CsA + Mil), respectively. Infarct sizes were determined by triphenyltetrazolium chloride (TTC) staining. The lowest and most cardioprotective concentration was 1 µM Mil (Mil 1: 32 ± 6%; p < 0.05 vs. Con: 63 ± 8% and Mil 0.3: 49 ± 6%). Pax and MPG blocked the infarct size reduction of Mil (Pax + Mil: 53 ± 6%, MPG + Mil: 59 ± 7%; p < 0.05 vs. Mil: 34 ± 6%) without having an effect on infarct size when administered alone (Pax: 53 ± 7%, MPG: 58 ± 5%; ns vs. Con). The combined administration of CsA completely restored the MPG-inhibited cardioprotection of Mil (MPG + Mil + CsA: 35 ± 7%, p < 0.05 vs. MPG + Mil). Milrinone concentration-dependently induces preconditioning. Cardioprotection is mediated by the activation of mBK_Ca-channels, release of ROS and mPTP inhibition.

Rhein protects the myocardiac cells against hypoxia/reoxygention-induced injury by suppressing GSK3β activity

BACKGROUND

Rhein, an anthraquinone compound isolated from rhubarb, has been shown to protect the pancreatic β cells from hyperglycemia induced apoptosis in our previous studies.

PURPOSE

In the present study, we examined whether rhein can protect myocardial cells against ischemia reperfusion (I/R)-induced apoptosis and investigated the underlying mechanism.

METHODS

We used an in vitro model of myocardial hypoxia/reoxygenation (H/R) injury. H9c2 cells were incubated with rhein for 1 h and then subjected to hypoxia for 6 h, followed by reoxygenation for 2 h. Cells viability, apoptosis and ROS were assayed for the treated cells. AKT, p-AKT, GSK3β, p- GSK3β, P38 and p-P38 proteins were analyzed using Western blotting. PI3K/AKT inhibitor, LY294002, and GSK3β siRNA were also used to determine the signaling pathways involved in the protection by rhein.

RESULTS

Rhein increased viability, decreased apoptosis and ROS production, of the cells that were exposed to H/R. Rhein also increased the phosphorylation of AKT and GSK3β, an effect that was eliminated by LY294002. GSK3β silencing by siRNA showed similar effect as LY294002. The p-P38 level was upregulated by H/R and downregulated in the presence of rhein; however, the p-P38 downregulation was completely abolished by GSK3β silencing.

CONCLUSION

Rhein protects myocardial H9c2 cells against hypoxia/reoxygenation induced injury via AKT/ GSK3β/p38 pathway.

Glycogen synthase kinase 3β promotes liver innate immune activation by restraining AMP-activated protein kinase activation

BACKGROUND & AIMS

Glycogen synthase kinase 3β (Gsk3β [Gsk3b]) is a ubiquitously expressed kinase with distinctive functions in different types of cells. Although its roles in regulating innate immune activation and ischaemia and reperfusion injuries (IRIs) have been well documented, the underlying mechanisms remain ambiguous, in part because of the lack of cell-specific tools in vivo.

METHODS

We created a myeloid-specific Gsk3b knockout (KO) strain to study the function of Gsk3β in macrophages in a murine liver partial warm ischaemia model.

RESULTS

Compared with controls, myeloid Gsk3b KO mice were protected from IRI, with diminished proinflammatory but enhanced anti-inflammatory immune responses in livers. In bone marrow-derived macrophages, Gsk3β deficiency resulted in an early reduction of Tnf gene transcription but sustained increase of Il10 gene transcription on Toll-like receptor 4 stimulation in vitro. These effects were associated with enhanced AMP-activated protein kinase (AMPK) activation, which led to an accelerated and higher level of induction of the novel innate immune negative regulator small heterodimer partner (SHP [Nr0b2]). The regulatory function of Gsk3β on AMPK activation and SHP induction was confirmed in wild-type bone marrow-derived macrophages with a Gsk3 inhibitor. Furthermore, we found that this immune regulatory mechanism was independent of Gsk3β Ser9 phosphorylation and the phosphoinositide 3-kinase-Akt signalling pathway. In vivo, myeloid Gsk3β deficiency facilitated SHP upregulation by ischaemia-reperfusion in liver macrophages. Treatment of Gsk3b KO mice with either AMPK inhibitor or SHP small interfering RNA before the onset of liver ischaemia restored liver proinflammatory immune activation and IRI in these otherwise protected hosts. Additionally, pharmacological activation of AMPK protected wild-type mice from liver IRI, with reduced proinflammatory immune activation. Inhibition of the AMPK-SHP pathway by liver ischaemia was demonstrated in tumour resection patients.

CONCLUSIONS

Gsk3β promotes innate proinflammatory immune activation by restraining AMPK activation.

LAY SUMMARY

Glycogen synthase kinase 3β promotes macrophage inflammatory activation by inhibiting the immune regulatory signalling of AMP-activated protein kinase and the induction of small heterodimer partner. Therefore, therapeutic targeting of glycogen synthase kinase 3β enhances innate immune regulation and protects liver from ischaemia and reperfusion injury.

Ehrlichia Activation of Wnt-PI3K-mTOR Signaling Inhibits Autolysosome Generation and Autophagic Destruction by the Mononuclear Phagocyte

In multicellular organisms, autophagy is induced as an innate defense mechanism. Notably, the obligate intracellular bacterium Ehrlichia chaffeensis resides in early endosome-like vacuoles and circumvents lysosomal fusion through an unknown mechanism, thereby avoiding destruction in the autophagolysosome. In this report, we reveal that Wnt signaling plays a crucial role in inhibition of lysosomal fusion and autolysosomal destruction of ehrlichiae. During early infection, autophagosomes fuse with ehrlichial vacuoles to form an amphisome indicated by the presence of autophagy markers such as LC3 (microtubule-associated protein 1 light chain 3), Beclin-1, and p62. LC3 colocalized with ehrlichial morulae on days 1, 2, and 3 postinfection, and increased LC3II levels were detected during infection, reaching a maximal level on day 3. Ehrlichial vacuoles did not colocalize with the lysosomal marker LAMP2, and lysosomes were redistributed and dramatically reduced in level in the infected cells. An inhibitor specific for the Wnt receptor signaling component Dishevelled induced lysosomal fusion with ehrlichial inclusions corresponding to p62 degradation and promoted transcription factor EB (TFEB) nuclear localization. E. chaffeensis infection activated the phosphatidylinositol 3-kinase (PI3K)-Akt-mTOR (mechanistic target of rapamycin) pathway, and activation was induced by three ehrlichial tandem repeat protein (TRP) effectors, with TRP120 inducing the strongest activation. Moreover, induction of glycogen synthase kinase-3 (GSK3) performed using a Wnt inhibitor and small interfering RNA (siRNA) knockdown of critical components of PI3K-GSK3-mTOR signaling decreased ehrlichial survival. This report reveals Ehrlichia exploitation of the evolutionarily conserved Wnt pathway to inhibit autolysosome generation, thereby leading to evasion of this important innate immune defense mechanism.

Wnt signaling in cardiovascular disease: opportunities and challenges

PURPOSE OF REVIEW

Cardiometabolic diseases increasingly afflict our aging, dysmetabolic population. Complex signals regulating low-density lipoprotein receptor-related protein (LRP) and frizzled protein family members - the plasma membrane receptors for the cadre of Wnt polypeptide morphogens - contribute to the control of cardiovascular homeostasis.

RECENT FINDINGS

Both canonical (β-catenin-dependent) and noncanonical (β-catenin-independent) Wnt signaling programs control vascular smooth muscle (VSM) cell phenotypic modulation in cardiometabolic disease. LRP6 limits VSM proliferation, reduces arteriosclerotic transcriptional reprogramming, and preserves insulin sensitivity while LRP5 restrains foam cell formation. Adipose, skeletal muscle, macrophages, and VSM have emerged as important sources of circulating Wnt ligands that are dynamically regulated during the prediabetes-diabetes transition with cardiometabolic consequences. Platelets release Dkk1, a LRP5/LRP6 inhibitor that induces endothelial inflammation and the prosclerotic endothelial-mesenchymal transition. By contrast, inhibitory secreted frizzled-related proteins shape the Wnt signaling milieu to limit myocardial inflammation with ischemia-reperfusion injury. VSM sclerostin, an inhibitor of canonical Wnt signaling in bone, restrains remodeling that predisposes to aneurysm formation, and is downregulated in aneurysmal vessels by epigenetic methylation.

SUMMARY

Components of the Wnt signaling cascade represent novel targets for pharmacological intervention in cardiometabolic disease. Conversely, strategies targeting the Wnt signaling cascade for other therapeutic purposes will have cardiovascular consequences that must be delineated to establish clinically useful pharmacokinetic-pharmacodynamic relationships.

CoQ0-induced mitochondrial PTP opening triggers apoptosis via ROS-mediated VDAC1 upregulation in HL-60 leukemia cells and suppresses tumor growth in athymic nude mice/xenografted nude mice

Coenzyme Q (CoQ) analogs with variable numbers of isoprenoid units have been demonstrated as anticancer and antioxidant/pro-oxidant molecules. This study examined the in vitro and in vivo antitumor and apoptosis activities of CoQ₀ (2,3-dimethoxy-5-methyl-1,4-benzoquinone, zero isoprenoid side-chains) through upregulation of the Voltage-dependent anion channel 1 (VDAC1) signaling pathway on human promyelocytic leukemia. CoQ₀ (0-40 μg/mL) treatment significantly reduced HL-60 cell viability, and up-regulated mitochondrial VDAC1 expression. CoQ₀ treatment triggers intracellular ROS generation, calcium release, ΔΨm collapse and PTP opening in HL-60 cells. CoQ₀ treatment induced apoptosis, which was associated with DNA fragmentation, cytochrome c release, caspase-3 and PARP activation, and Bax/Bcl-2 dysregulation. Annexin V-PI staining indicated that CoQ₀ promotes late apoptosis. Furthermore, the blockade of CoQ₀-induced ROS production by antioxidant NAC pretreatment substantially attenuated CoQ₀-induced apoptosis. The activation of p-GSK3β expression, cyclophilin D inhibition, and p53 activation through ROS are involved in CoQ₀-induced HL-60 apoptotic cell death. Notably, ROS-independent p38 activation is involved in CoQ₀-mediated apoptosis in HL-60 cells. In addition, the silencing of VDAC1 also prevented CoQ₀-induced mitochondrial translocation of Bax, activation of caspase-3, and reduction in Bcl-2. Intriguingly, VDAC1 silencing did not prevent ROS production induced by CoQ₀, which in turn indicates that CoQ₀ induced ROS-mediated VDAC1 and then mitochondrial apoptosis in HL-60 cells. In vivo results revealed that CoQ₀ is effective in delaying tumor incidence and reducing the tumor burden in HL-60-xenografted nude mice. Taken together, CoQ₀ could be a promising anticancer agent for the treatment of human promyelocytic leukemia through upregulation of VDAC1 signaling pathways.

GSK3 inhibitor AR-A014418 promotes osteogenic differentiation of human adipose-derived stem cells via ERK and mTORC2/Akt signaling pathway

Small molecule-based bone tissue engineering is emerging as a promising strategy for bone defects restoration. In this study, we intended to identify the roles and mechanisms of AR-A014418, a highly selective inhibitor of GSK3, on the osteogenic differentiation. We found that AR-A014418 exhibited a dose-dependent effect on osteogenic differentiation of human adipose-derived stem cells (hASCs). hASCs treated with AR-A014418 showed higher activity of ERK and mTORC2/Akt signaling. Administration of ERK inhibitor U0126 or knockdown of RICTOR by siRNA attenuated AR-A014418 induced osteogenic differentiation of hASCs. Our results suggested that AR-A014418 significantly promoted osteogenic potential of hASCs partially by the activation of ERK and mTORC2/Akt signaling pathway, and might be used for bone tissue engineering as an osteo-inductive factor.

Insights for Oxidative Stress and mTOR Signaling in Myocardial Ischemia/Reperfusion Injury under Diabetes

Diabetes mellitus (DM) displays a high morbidity. The diabetic heart is susceptible to myocardial ischemia/reperfusion (MI/R) injury. Impaired activation of prosurvival pathways, endoplasmic reticulum (ER) stress, increased basal oxidative state, and decreased antioxidant defense and autophagy may render diabetic hearts more vulnerable to MI/R injury. Oxidative stress and mTOR signaling crucially regulate cardiometabolism, affecting MI/R injury under diabetes. Producing reactive oxygen species (ROS) and reactive nitrogen species (RNS), uncoupling nitric oxide synthase (NOS), and disturbing the mitochondrial quality control may be three major mechanisms of oxidative stress. mTOR signaling presents both cardioprotective and cardiotoxic effects on the diabetic heart, which interplays with oxidative stress directly or indirectly. Antihyperglycemic agent metformin and newly found free radicals scavengers, Sirt1 and CTRP9, may serve as promising pharmacological therapeutic targets. In this review, we will focus on the role of oxidative stress and mTOR signaling in the pathophysiology of MI/R injury in diabetes and discuss potential mechanisms and their interactions in an effort to provide some evidence for cardiometabolic targeted therapies for ischemic heart disease (IHD).

Effect of pioglitazone on the abrogated cardioprotective effect of ischemic preconditioning in hyperlipidemic rat heart

Objectives:

The signaling pathways upstream of glycogen synthase kinase-3β (GSK-3β) get reduced during ischemic preconditioning (IPC) in hyperlipidemic rat heart. Pioglitazone, an insulin sensitizer, exerts cardioprotection through GSK-3β. The objective of the study is to investigate the role of pioglitazone on the attenuated cardioprotective effect of IPC in hyperlipidemic rat heart.

Materials and Methods:

The rats were administered high-fat diet for 8 weeks to induce experimental hyperlipidemia (HL). After mounting on a Langendorff apparatus, isolated perfused hearts were given four cycles of IPC; each consists of 5 min of both ischemia and reperfusion followed by 30 min of ischemia and 120 min of reperfusion. Insulin (50 mU/ml) was perfused alone and in combination with pioglitazone (2 μM), while in other groups, this combination was repeated with wortmannin (100 nM), a selective PI3K inhibitor and rapamycin (1 nM), a selective mammalian target of rapamycin (mTOR) inhibitor, separately, and in combination. Myocardial injury was assessed by measuring infarct size and the levels of creatinine kinase-myocardial band (CK-MB) and lactate dehydrogenase (LDH) in the coronary effluent.

Results:

IPC significantly decreased the infarct size and levels of LDH and CK-MB in normal but not in HL rat heart. Perfusion of insulin along with pioglitazone significantly reduced the infarct size and release of CK-MB and LDH in IPC-treated HL rat hearts. Perfusion of wortmannin or rapamycin alone significantly and in combination almost completely abolished the pioglitazone-induced restored cardioprotection (P < 0.05).

Conclusion:

Cardioprotective effect of IPC gets lost in hyperlipidemic rat heart. The results suggest that perfusion of pioglitazone restored the cardioprotective effect of IPC in hyperlipidemic rat heart, an effect that may be via PI3K and mTOR.

Inorganic polyphosphate promotes cyclin D1 synthesis through activation of mTOR/Wnt/β-catenin signaling in endothelial cells

Essentials Polyphosphate (polyP) activates mTOR but its role in Wnt/β-catenin signaling is not known. PolyP-mediated cyclin D1 expression (β-catenin target gene) was monitored in endothelial cells. PolyP and boiled platelet-releasates induced the expression of cyclin D1 by similar mechanisms. PolyP establishes crosstalk between mTOR and Wnt/β-catenin signaling in endothelial cells.

SUMMARY

Background Inorganic polyphosphate (polyP) elicits intracellular signaling responses in endothelial cells through activation of mTOR complexes 1 and 2. Glycogen synthase kinase 3 (GSK-3) is known to be a negative regulator of mTOR and Wnt/β-catenin signaling pathways. Objective The objective of this study was to investigate the effect of polyP on the expression, degradation and subcellular localization of the Wnt/β-catenin target gene, cyclin D1, in endothelial cells. Methods Regulation of cyclin D1 expression, phosphorylation and subcellular localization by polyP or platelet releasates was monitored in the absence and presence of pharmacological inhibitors and/or siRNA for specific molecules of the upstream mTOR/Wnt/β-catenin signaling network by established methods. Results Both synthetic polyP and boiled-platelet releasates induced the phosphorylation-dependent inactivation of GSK-3, thereby increasing the expression and nuclear localization, but inhibiting the degradation of cyclin D1. Inhibitors of mTORC1 (PI3K, AKT, PLC, PKC), rapamycin and siRNA for raptor (mTORC1-specific component) and β-catenin, all inhibited polyP-mediated regulation of cyclin D1 expression, phosphorylation and subcellular localization in endothelial cells. The signaling effect of polyP was effectively inhibited by the recombinant extracellular domain of the receptor for advanced glycation end products (RAGE) and/or by the RAGE siRNA. Specific pharmacological inhibitors and siRNA knockdown of ERK1/2 and NF-κB pathways indicated that polyP-mediated cyclin D1 expression and nuclear localization are IKKɑ and ERK1/2 dependent, whereas its inhibitory effect on phosphorylation-dependent degradation of cyclin D1 is IKKβ-dependent. Conclusion We conclude that a RAGE-dependent polyP-mediated crosstalk between mTOR and the GSK-3/Wnt/β-catenin signaling network can modulate important physiological processes in endothelial cells.

Wnt Signaling in Cardiac Disease

Wnt signaling encompasses multiple and complex signaling cascades and is involved in many developmental processes such as tissue patterning, cell fate specification, and control of cell division. Consequently, accurate regulation of signaling activities is essential for proper embryonic development. Wnt signaling is mostly silent in the healthy adult organs but a reactivation of Wnt signaling is generally observed under pathological conditions. This has generated increasing interest in this pathway from a therapeutic point of view. In this review article, the involvement of Wnt signaling in cardiovascular development will be outlined, followed by its implication in myocardial infarct healing, cardiac hypertrophy, heart failure, arrhythmias, and atherosclerosis. The initial experiments not always offer consensus on the effects of activation or inactivation of the pathway, which may be attributed to (i) the type of cardiac disease, (ii) timing of the intervention, and (iii) type of cells that are targeted. Therefore, more research is needed to determine the exact implication of Wnt signaling in the conditions mentioned above to exploit it as a powerful therapeutic target.

MicroRNA-21 Mediates Isoflurane-induced Cardioprotection against Ischemia-Reperfusion Injury via Akt/Nitric Oxide Synthase/Mitochondrial Permeability Transition Pore Pathway

BACKGROUND

The role of microRNA-21 in isoflurane-induced cardioprotection is unknown. The authors addressed this issue by using microRNA-21 knockout mice and explored the underlying mechanisms.

METHODS

C57BL/6 and microRNA-21 knockout mice were echocardiographically examined. Mouse hearts underwent 30 min of ischemia followed by 2 h of reperfusion in vivo or ex vivo in the presence or absence of 1.0 minimum alveolar concentration of isoflurane administered before ischemia. Cardiac Akt, endothelial nitric oxide synthase (eNOS), and neuronal nitric oxide synthase (nNOS) proteins were determined by Western blot analysis. Opening of the mitochondrial permeability transition pore (mPTP) in cardiomyocytes was induced by photoexcitation-generated oxidative stress and detected by rapid dissipation of tetramethylrhodamine ethyl ester fluorescence using a confocal microscope.

RESULTS

Genetic disruption of miR-21 gene did not alter phenotype of the left ventricle, baseline cardiac function, area at risk, and the ratios of phosphorylated-Akt/Akt, phosphorylated-eNOS/eNOS, and phosphorylated-nNOS/nNOS. Isoflurane decreased infarct size from 54 ± 10% in control to 36 ± 10% (P < 0.05, n = 8 mice per group), improved cardiac function after reperfusion, and increased the ratios of phosphorylated-Akt/AKT, phosphorylated-eNOS/eNOS, and phosphorylated-nNOS/nNOS in C57BL/6 mice subjected to ischemia-reperfusion injury. These beneficial effects of isoflurane were lost in microRNA-21 knockout mice. There were no significant differences in time of the mPTP opening induced by photoexcitation-generated oxidative stress in cardiomyocytes isolated between C57BL/6 and microRNA-21 knockout mice. Isoflurane significantly delayed mPTP opening in cardiomyocytes from C57BL/6 but not from microRNA-21 knockout mice.

CONCLUSIONS

Isoflurane protects mouse hearts from ischemia-reperfusion injury by a microRNA-21-dependent mechanism. The Akt/NOS/mPTP pathway is involved in the microRNA-21-mediated protective effect of isoflurane.

Bauhinia championii flavone inhibits apoptosis and autophagy via the PI3K/Akt pathway in myocardial ischemia/reperfusion injury in rats

This study aimed to determine the effects of Bauhinia championii flavone (BCF) on myocardial ischemia/reperfusion injury (MI/RI) in rats and to explore potential mechanisms. The MI/RI model in rats was established by ligating the left anterior descending coronary artery for 30 minutes, then reperfusing for 3 hours. BCF at 20 mg/kg was given 20 minutes prior to ischemia via sublingual intravenous injection, with 24 μg/kg phosphoinositide 3-kinase inhibitor (PI3K; wortmannin) as a control. The creatine kinase-MB and nitric oxide content were assessed by colorimetry. The levels of mitochondrial permeability transition pores and tumor necrosis factor alpha were determined by an enzyme-linked immunosorbent assay. Cardiomyocyte apoptosis was detected by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Additionally, the expression of PI3K, endothelial nitric oxide synthase, caspase-3, and Beclin1 was analyzed by fluorescence quantitative polymerase chain reaction and Western blotting, respectively. Akt and microtubule-associated protein 1 light chain 3-II protein levels were also evaluated. Pretreatment with BCF significantly decreased the levels of creatine kinase-MB, tumor necrosis factor alpha, and mitochondrial permeability transition pores, but increased the nitric oxide content. Furthermore, BCF inhibited apoptosis, downregulated caspase-3, Beclin1, and microtubule-associated protein 1 light chain 3-II, upregulated PI3K, and increased the protein levels of phosphorylated Akt and endothelial nitric oxide synthase. However, all of the previously mentioned effects of BCF were blocked when BCF was coadministered with wortmannin. In conclusion, these observations indicated that BCF has cardioprotective effects against MI/RI by reducing cell apoptosis and excessive autophagy, which might be related to the activation of the PI3K/Akt signaling pathway.

Apelin-13 protects the heart against ischemia-reperfusion injury through the RISK-GSK-3β-mPTP pathway

INTRODUCTION

Apelin plays an important role in the protection against myocardial ischemia-reperfusion (I/R) injury, while the mechanism still remains unclear. In the current study, we aimed to evaluate the protective effect of apelin-13, and the main mechanism.

MATERIAL AND METHODS

The in vivo I/R injury model (Sprague-Dawley rat) was established, then infarct size, expression levels of phospho-protein kinase B (p-Akt), phospho-extracellular signal-regulated kinase (p-ERK) and phospho-glycogen synthase kinase-3β (p-GSK-3β) were measured. The fluorescence intensity of tetramethylrhodamine ethyl ester perchlorate (TMRE) of the isolated myocardial cells was determined to evaluate the opening of the mitochondrial permeability transition pore (mPTP) caused by oxidant stress and hypoxia/reoxygenation.

RESULTS

For the established I/R injury model, apelin-13 and SB216763 (GSK-3β inhibitor) significantly reduced the infarct size (p < 0.05), which could be abolished by LY294002 (PI3K inhibitor), PD98059 (MEK inhibitor) and atractyloside (mPTP accelerator). The enhanced expression levels of p-Akt, p-ERK and p-GSK-3β caused by apelin-13 (p < 0.05) could be counteracted by LY294002 and PD98059. The reduced fluorescence intensity of TMRE in the H2O2/apelin-13 and H2O2/SB216763 treated groups was significantly lower (p < 0.05), indicating that apelin-13 and SB216763 could reduce the decline in mitochondrial membrane potential caused by oxidant stress, and the fluorescence intensity in the hypoxia/reoxygenation + apelin-13 group was significantly lower (p < 0.05), which suggested that apelin-13 could inhibit the mitochondrial membrane potential changes induced by hypoxia/reoxygenation.

CONCLUSIONS

The protective mechanism of apelin-13 might be that inactivation of GSK-3β could inhibit the opening of mPTP by activating PI3K/Akt and ERK1/2 involved in the reperfusion injury salvage kinase (RISK) pathway.

Role of Opioid Receptors Signaling in Remote Electrostimulation--Induced Protection against Ischemia/Reperfusion Injury in Rat Hearts

Aims

Our previous studies demonstrated that remote electro-stimulation (RES) increased myocardial GSK3 phosphorylation and attenuated ischemia/ reperfusion (I/R) injury in rat hearts. However, the role of various opioid receptors (OR) subtypes in preconditioned RES-induced myocardial protection remains unknown. We investigated the role of OR subtype signaling in RES-induced cardioprotection against I/R injury of the rat heart.

Methods & Results

Male Spraque-Dawley rats were used. RES was performed on median nerves area with/without pretreatment with various receptors antagonists such as opioid receptor (OR) subtype receptors (KOR, DOR, and MOR). The expressions of Akt, GSK3, and PKCε expression were analyzed by Western blotting. When RES was preconditioned before the I/R model, the rat's hemodynamic index, infarction size, mortality and serum CK-MB were evaluated. Our results showed that Akt, GSK3 and PKCε expression levels were significantly increased in the RES group compared to the sham group, which were blocked by pretreatment with specific antagonists targeting KOR and DOR, but not MOR subtype. Using the I/R model, the duration of arrhythmia and infarct size were both significantly attenuated in RES group. The mortality rates of the sham RES group, the RES group, RES group + KOR antagonist, RES group + DOR/MOR antagonists (KOR left), RES group + DOR antagonist, and RES group + KOR/MOR antagonists (DOR left) were 50%, 20%, 67%, 13%, 50% and 55%, respectively.

Conclusion

The mechanism of RES-induced myocardial protection against I/R injury seems to involve multiple target pathways such as Akt, KOR and/or DOR signaling.

E2F1-dependent miR-421 regulates mitochondrial fragmentation and myocardial infarction by targeting Pink1

Mitochondrial fragmentation plays an important role in the progression of cardiac diseases, such as myocardial infarction and heart failure. Mitochondrial network is controlled by many factors in different cell types. Here we show that the interplay between E2F1, miR-421 and Pink1 regulates mitochondrial morphology and cardiomyocyte cell death. Pink1 reduces mitochondrial fragmentation and protects cardiomyocyte from apoptosis. On the other hand, miR-421 promotes cardiomyocyte mitochondrial fragmentation, apoptosis and myocardial infarction by suppressing Pink1 translation. Finally, we show that transcription factor E2F1 activates miR-421 expression. Knocking down E2F1 suppresses mitochondrial fragmentation, apoptosis and myocardial infarction by affecting miR-421 levels. Collectively, these data identify the E2F1/miR-421/Pink axis as a regulator of mitochondrial fragmentation and cardiomyocyte apoptosis, and suggest potential therapeutic targets in treatment of cardiac diseases.

Cardioprotective Signature of Short-Term Caloric Restriction

Objective

To understand the molecular pathways underlying the cardiac preconditioning effect of short-term caloric restriction (CR).

Background

Lifelong CR has been suggested to reduce the incidence of cardiovascular disease through a variety of mechanisms. However, prolonged adherence to a CR life-style is difficult. Here we reveal the pathways that are modulated by short-term CR, which are associated with protection of the mouse heart from ischemia.

Methods

Male 10-12 wk old C57bl/6 mice were randomly assigned to an ad libitum (AL) diet with free access to regular chow, or CR, receiving 30% less food for 7 days (d), prior to myocardial infarction (MI) via permanent coronary ligation. At d8, the left ventricles (LV) of AL and CR mice were collected for Western blot, mRNA and microRNA (miR) analyses to identify cardioprotective gene expression signatures. In separate groups, infarct size, cardiac hemodynamics and protein abundance of caspase 3 was measured at d2 post-MI.

Results

This short-term model of CR was associated with cardio-protection, as evidenced by decreased infarct size (18.5±2.4% vs. 26.6±1.7%, N=10/group; P=0.01). mRNA and miR profiles pre-MI (N=5/group) identified genes modulated by short-term CR to be associated with circadian clock, oxidative stress, immune function, apoptosis, metabolism, angiogenesis, cytoskeleton and extracellular matrix (ECM). Western blots pre-MI revealed CR-associated increases in phosphorylated Akt and GSK3ß, reduced levels of phosphorylated AMPK and mitochondrial related proteins PGC-1α, cytochrome C and cyclooxygenase (COX) IV, with no differences in the levels of phosphorylated eNOS or MAPK (ERK1/2; p38). CR regimen was also associated with reduced protein abundance of cleaved caspase 3 in the infarcted heart and improved cardiac function.

Role of MEK, PI3, p38, Tyrosine, and mTOR Kinases in Regulation of Heart Resistance to the Arrhythmogenic Action of Short-Term Ischemia and Reperfusion

MEK, PI3, p38, tyrosine, and mTOR kinases are not involved in the regulation of heart resistance to the arrhythmogenic action of short-term ischemia/reperfusion in non-adapted rats.