Involvement of phosphoinositide 3-kinase gamma in angiogenesis and healing of experimental myocardial infarction in mice

The role of PI3Kγ in the immune system: new insights and translational implications

Over the past two decades, new insights have positioned phosphoinositide 3-kinase-γ (PI3Kγ) as a context-dependent modulator of immunity and inflammation. Recent advances in protein structure determination and drug development have allowed for generation of highly specific PI3Kγ inhibitors, with the first now in clinical trials for several oncology indications. Recently, a monogenic immune disorder caused by PI3Kγ deficiency was discovered in humans and modelled in mice. Human inactivated PI3Kγ syndrome confirms the immunomodulatory roles of PI3Kγ and strengthens newly defined roles of this molecule in modulating inflammatory cytokine release in macrophages. Here, we review the functions of PI3Kγ in the immune system and discuss how our understanding of its potential as a therapeutic target has evolved.

Inhibition of Phosphoinositide 3-Kinase Gamma Protects Endothelial Cells via the Akt Signaling Pathway in Sepsis-Induced Acute Kidney Injury

INTRODUCTION

Sepsis is a primary cause of death in critically ill patients and is characterized by multiple organ dysfunction, including sepsis-induced acute kidney injury (AKI), which contributes to high mortality in sepsis. However, its pathophysiological mechanisms remain unclear. The kidney has one of the richest and most diversified endothelial cell populations in the body. This study was designed to investigate the effects of endothelial dysfunction in sepsis-induced AKI and explore possible intervention measures to offer new insight into the pathogenesis and treatment of sepsis-induced AKI.

METHODS

The circulating levels of endothelial adhesion molecules were detected in patients with sepsis and healthy controls to observe the role of endothelial damage in sepsis and sepsis-induced AKI. A murine sepsis model induced by cecal ligation and perforation was pretreated with a phosphoinositide 3-kinase gamma (PI3Kγ) inhibitor (CZC24832), and survival, kidney damage, and renal endothelial injury were assessed by pathological examination, immunohistochemistry, quantitative polymerase chain reaction, and Western blotting. Lipopolysaccharides and CZC24832 were administered to human umbilical vein endothelial cells in vitro, and endothelial cell function and the expression of adhesion molecules were evaluated.

RESULTS

Endothelial damage was more serious in sepsis-induced AKI than that in non-AKI, and the inhibition of PI3Kγ alleviates renal endothelial injury in a murine sepsis model, protecting endothelial cell function and repairing endothelial cell injury through the Akt signaling pathway.

CONCLUSIONS

In this study, endothelial cell dysfunction plays an important role in sepsis-induced AKI, and the inhibition of PI3Kγ alleviates endothelial cell injury in sepsis-induced AKI through the PI3Kγ/Akt pathway, providing novel targets for treating sepsis and related kidney injury.

Anti-Ischemic Effects of PIK3IP1 Are Mediated through Its Interactions with the ETA-PI3Kγ-AKT Axis

Oxidative stress, caused by the accumulation of reactive oxygen species (ROS) during acute myocardial infarction (AMI), is one of the main factors leading to myocardial cell damage and programmed cell death. Phosphatidylinositol-3-kinase-AKT (PI3K-AKT) signaling is essential for regulating cell proliferation, differentiation, and apoptosis. Phosphoinositide-3-kinase (PI3K)-interacting protein 1 (PIK3IP1) is an intrinsic inhibitor of PI3K in various tissues, but its functional role during AMI remains unknown. In this study, the anti-ischemic role of PIK3IP1 in an in vitro AMI setting was evaluated using H9c2 cells. The MTT assay demonstrated that cell viability decreased significantly via treatment with H₂O₂ (200–500 μM). The TUNEL assay results revealed substantial cellular apoptosis following treatment with 200 μM H₂O₂. Under the same conditions, the expression levels of hypoxia-inducible factor (HIF-1α), endothelin-1 (ET-1), bcl-2-like protein 4 (BAX), and cleaved caspase-3 were elevated, whereas those of PIK3IP1, LC3II, p53, and Bcl-2 decreased significantly. PIK3IP1 overexpression inhibited H₂O₂-induced and PI3K-mediated apoptosis; however, PIK3IP1 knockdown reversed this effect, suggesting that PIK3IP1 functions as an anti-apoptotic molecule. To identify both the upstream and downstream molecules associated with PIK3IP1, ET-1 receptor type-specific antagonists (BQ-123 and BQ-788) and PI3K subtype-specific antagonists (LY294002 and IPI-549) were used to determine the participating isoforms. Co-immunoprecipitation was performed to identify the binding partners of PIK3IP1. Our results demonstrated that ROS-induced cardiac cell death may occur through the ETA-PI3Kγ-AKT axis, and that PIK3IP1 inhibits binding with both ETA and PI3Kγ. Taken together, these findings reveal that PIK3IP1 plays an anti-ischemic role by reducing the likelihood of programmed cell death via interaction with the ETA-PI3Kr-AKT axis.

Reconstituted HDL-apoE3 promotes endothelial cell migration through ID1 and its downstream kinases ERK1/2, AKT and p38 MAPK

INTRODUCTION

Atherosclerotic Coronary Artery Disease (ASCAD) is the leading cause of mortality worldwide. Novel therapeutic approaches aiming to improve the atheroprotective functions of High Density Lipoprotein (HDL) include the use of reconstituted HDL forms containing human apolipoprotein A-I (rHDL-apoA-I). Given the strong atheroprotective properties of apolipoprotein E3 (apoE3), rHDL-apoE3 may represent an attractive yet largely unexplored therapeutic agent.

OBJECTIVE

To evaluate the atheroprotective potential of rHDL-apoE3 starting with the unbiased assessment of global transcriptome effects and focusing on endothelial cell (EC) migration as a critical process in re-endothelialization and atherosclerosis prevention. The cellular, molecular and functional effects of rHDL-apoE3 on EC migration-associated pathways were assessed, as well as the potential translatability of these findings in vivo.

METHODS

Human Aortic ECs (HAEC) were treated with rHDL-apoE3 and total RNA was analyzed by whole genome microarrays. Expression and phosphorylation changes of key EC migration-associated molecules were validated by qRT-PCR and Western blot analysis in primary HAEC, Human Coronary Artery ECs (HCAEC) and the human EA.hy926 EC line. The capacity of rHDL-apoE3 to stimulate EC migration was assessed by wound healing and transwell migration assays. The contribution of MEK1/2, PI3K and the transcription factor ID1 in rHDL-apoE3-induced EC migration and activation of EC migration-related effectors was assessed using specific inhibitors (PD98059: MEK1/2, LY294002: PI3K) and siRNA-mediated gene silencing, respectively. The capacity of rHDL-apoE3 to improve vascular permeability and hypercholesterolemia in vivo was tested in a mouse model of hypercholesterolemia (apoE KO mice) using Evans Blue assays and lipid/lipoprotein analysis in the serum, respectively.

RESULTS

rHDL-apoE3 induced significant expression changes in 198 genes of HAEC mainly involved in re-endothelialization and atherosclerosis-associated functions. The most pronounced effect was observed for EC migration, with 42/198 genes being involved in the following EC migration-related pathways: 1) MEK/ERK, 2) PI3K/AKT/eNOS-MMP2/9, 3) RHO-GTPases, 4) integrin. rHDL-apoE3 induced changes in 24 representative transcripts of these pathways in HAEC, increasing the expression of their key proteins PIK3CG, EFNB2, ID1 and FLT1 in HCAEC and EA.hy926 cells. In addition, rHDL-apoE3 stimulated migration of HCAEC and EA.hy926 cells, and the migration was markedly attenuated in the presence of PD98059 or LY294002. rHDL-apoE3 also increased the phosphorylation of ERK1/2, AKT, eNOS and p38 MAPK in these cells, while PD98059 and LY294002 inhibited rHDL-apoE3-induced phosphorylation of ERK1/2, AKT and p38 MAPK, respectively. LY had no effect on rHDL-apoE3-mediated eNOS phosphorylation. ID1 siRNA markedly decreased EA.hy926 cell migration by inhibiting rHDL-apoE3-triggered ERK1/2 and AKT phosphorylation. Finally, administration of a single dose of rHDL-apoE3 in apoE KO mice markedly improved vascular permeability as demonstrated by the reduced concentration of Evans Blue dye in tissues such as the stomach, the tongue and the urinary bladder and ameliorated hypercholesterolemia.

CONCLUSIONS

rHDL-apoE3 significantly enhanced EC migration in vitro, predominantly via overexpression of ID1 and subsequent activation of MEK1/2 and PI3K, and their downstream targets ERK1/2, AKT and p38 MAPK, respectively, and improved vascular permeability in vivo. These novel insights into the rHDL-apoE3 functions suggest a potential clinical use to promote re-endothelialization and retard development of atherosclerosis.

PI3K as Mediator of Apoptosis and Contractile Dysfunction in TGFβ1-Stimulated Cardiomyocytes

BACKGROUND

TGFβ₁ is a growth factor that plays a major role in the remodeling process of the heart by inducing cardiomyocyte dysfunction and apoptosis, as well as fibrosis thereby restricting heart function. TGFβ₁ mediates its effect via the TGFβ receptor I (ALK5) and the activation of SMAD transcription factors, but TGFβ₁ is also known as activator of phosphoinositide-3-kinase (PI3K) via the non-SMAD signaling pathway. The aim of this study was to investigate whether PI3K is also involved in TGFβ₁-induced cardiomyocytes apoptosis and contractile dysfunction.

METHODS AND RESULTS

Incubation of isolated ventricular cardiomyocytes with TGFβ₁ resulted in impaired contractile function. Pre-incubation of cells with the PI3K inhibitor Ly294002 or the ALK5 inhibitor SB431542 attenuated the decreased cell shortening in TGFβ₁-stimulated cells. Additionally, TGFβ-induced apoptosis was significantly reduced by the PI3K inhibitor Ly294002. Administration of a PI3Kγ-specific inhibitor AS605240 abolished the TGFβ effect on apoptosis and cell shortening. This was also confirmed in cardiomyocytes from PI3Kγ KO mice. Induction of SMAD binding activity and the TGFβ target gene collagen 1 could be blocked by the PI3K inhibitor Ly294002, but not by the specific PI3Kγ inhibitor AS605240.

CONCLUSIONS

TGFβ₁-induced SMAD activation, cardiomyocyte apoptosis, and impaired cell shortening are mediated via both, the ALK5 receptor and PI3K, in adult cardiomyocytes. PI3Kγ specifically contributes to apoptosis induction and impairment of contractile function independent of SMAD signaling.

Role of PI3K in the Progression and Regression of Atherosclerosis

Phosphatidylinositol 3 kinase (PI3K) is a key molecule in the initiation of signal transduction pathways after the binding of extracellular signals to cell surface receptors. An intracellular kinase, PI3K activates multiple intracellular signaling pathways that affect cell growth, proliferation, migration, secretion, differentiation, transcription and translation. Dysregulation of PI3K activity, and as aberrant PI3K signaling, lead to a broad range of human diseases, such as cancer, immune disorders, diabetes, and cardiovascular diseases. A growing number of studies have shown that PI3K and its signaling pathways play key roles in the pathophysiological process of atherosclerosis. Furthermore, drugs targeting PI3K and its related signaling pathways are promising treatments for atherosclerosis. Therefore, we have reviewed how PI3K, an important regulatory factor, mediates the development of atherosclerosis and how targeting PI3K can be used to prevent and treat atherosclerosis.

Metabolomics study of dried ginger extract on serum and urine in blood stasis rats based on UPLC-Q-TOF/MS

Blood stasis syndrome (BSS) is the pathological basis of many cardiovascular diseases. Ginger is often used as herbal medicine, condiment, and health food in China and Southeast Asia to improve some symptoms of cardiovascular disease, but its mechanism of efficacy and metabolic processes is not clear enough. In this study, a rat model of BSS was successfully established and treated with different doses of dried ginger extract. After the end of the administration period, the blood and urine of 5 groups of rats were collected for metabonomic analysis. Multivariate statistical analysis was used to explore metabolites and metabolic pathways, and the correlation between metabolites and pharmacodynamic indicators was further explored. The experimental results show that the pharmacodynamic indicators of dried ginger group (DG) extracts of different doses have different degrees of changes than model group (MG), and the high dose of dried ginger group (GJH) changes is the most significant (p < .05 or p < .01). Besides, 22 different metabolites were identified in the experiment. These metabolites mainly involve seven metabolism pathways in different impact value. DG has therapeutic effects on BSS rats by regulating multiple metabolic pathways. This study provides an effective method for understanding the metabolic mechanism of DG extracts on BSS.

Pharmacological effects and mechanisms of muscone

Musk, the dried secretion from the preputial follicles of the male musk deer (genus Moschus), possesses various pharmacological activities and has been used extensively in traditional Chinese medicine for thousands of years. Muscone is the main active ingredient of musk and exerts pharmacological effects similar to those of musk. Although muscone was notably used to treat various disorders and diseases, such as neurological disorders, chronic inflammation and ischemia-reperfusion injury, most of the mechanisms of the pharmacological action of muscone remain unclear because of slow progress in research before the 21st century. In recent years, the pharmacological activities and mechanisms of muscone have been clarified. The present article summarizes the pharmacological and biological studies on cerebrovascular disease, cardiovascular disease, neurological effects, cancer and others and the associated mechanisms of the action of muscone to date.

Smooth muscle cells-derived CXCL10 prevents endothelial healing through PI3Kγ-dependent T cells response

AIMS

Defects in efficient endothelial healing have been associated with complication of atherosclerosis such as post-angioplasty neoatherosclerosis and plaque erosion leading to thrombus formation. However, current preventive strategies do not consider re-endothelialization in their design. Here, we investigate mechanisms linking immune processes and defect in re-endothelialization. We especially evaluate if targeting phosphoinositide 3-kinase γ immune processes could restore endothelial healing and identify immune mediators responsible for these defects.

METHODS AND RESULTS

Using in vivo model of endovascular injury, we showed that both ubiquitous genetic inactivation of PI3Kγ and hematopoietic cell-specific PI3Kγ deletion improved re-endothelialization and that CD4+ T-cell population drives this effect. Accordingly, absence of PI3Kγ activity correlates with a decrease in local IFNγ secretion and its downstream interferon-inducible chemokine CXCL10. CXCL10 neutralization promoted re-endothelialization in vivo as the same level than those observed in absence of PI3Kγ suggesting a role of CXCL10 in re-endothelialization defect. Using a new established ex vivo model of carotid re-endothelialization, we showed that blocking CXCL10 restore the IFNγ-induced inhibition of endothelial healing and identify smooth muscle cells as the source of CXCL10 secretion in response to Th1 cytokine.

CONCLUSION

Altogether, these findings expose an unforeseen cellular cross-talk within the arterial wall whereby a PI3Kγ-dependent T-cell response leads to CXCL10 production by smooth muscle cells which in turn inhibits endothelial healing. Therefore, both PI3Kγ and the IFNγ/CXCL10 axis provide novel strategies to promote endothelial healing.

Recent discovery of phosphoinositide 3-kinase γ inhibitors for the treatment of immune diseases and cancers

Recently, PI3Kγ, a vital kinase, which involved in numerous intracellular signaling pathways, has been considered as a promising drug target for the treatment of immune diseases and certain cancers. Before the 21st century, few selective PI3Kγ inhibitors were discovered because no non-conserved structure in the ATP binding sites of PI3Kγ had been found. Since the discovery of the non-ATP binding pocket, the reported structures of potent and selective PI3Kγ inhibitors have become more diverse, and one compound (IPI549) has entered Phase I clinical trial. This review centers on a general overview of PI3Kγ inhibitors in clinical and preclinical as well as further therapeutic applications in human diseases.

Small extracellular vesicles secreted from human amniotic fluid mesenchymal stromal cells possess cardioprotective and promigratory potential

Mesenchymal stromal cells (MSCs) exhibit antiapoptotic and proangiogenic functions in models of myocardial infarction which may be mediated by secreted small extracellular vesicles (sEVs). However, MSCs have frequently been harvested from aged or diseased patients, while the isolated sEVs often contain high levels of impurities. Here, we studied the cardioprotective and proangiogenic activities of size-exclusion chromatography-purified sEVs secreted from human foetal amniotic fluid stem cells (SS-hAFSCs), possessing superior functional potential to that of adult MSCs. We demonstrated for the first time that highly pure (up to 1.7 × 1010 particles/µg protein) and thoroughly characterised SS-hAFSC sEVs protect rat hearts from ischaemia-reperfusion injury in vivo when administered intravenously prior to reperfusion (38 ± 9% infarct size reduction, p < 0.05). SS-hAFSC sEVs did not protect isolated primary cardiomyocytes in models of simulated ischaemia-reperfusion injury in vitro, indicative of indirect cardioprotective effects. SS-hAFSC sEVs were not proangiogenic in vitro, although they markedly stimulated endothelial cell migration. Additionally, sEVs were entirely responsible for the promigratory effects of the medium conditioned by SS-hAFSC. Mechanistically, sEV-induced chemotaxis involved phosphatidylinositol 3-kinase (PI3K) signalling, as its pharmacological inhibition in treated endothelial cells reduced migration by 54 ± 7% (p < 0.001). Together, these data indicate that SS-hAFSC sEVs have multifactorial beneficial effects in a myocardial infarction setting.

PI3K inhibitors in thrombosis and cardiovascular disease

Phosphoinositide 3-kinases (PI3Ks) are lipid kinases that regulate important intracellular signalling and vesicle trafficking events via the generation of 3-phosphoinositides. Comprising eight core isoforms across three classes, the PI3K family displays broad expression and function throughout mammalian tissues, and the (patho)physiological roles of these enzymes in the cardiovascular system present the PI3Ks as potential therapeutic targets in settings such as thrombosis, atherosclerosis and heart failure. This review will discuss the PI3K enzymes and their roles in cardiovascular physiology and disease, with a particular focus on platelet function and thrombosis. The current progress and future potential of targeting the PI3K enzymes for therapeutic benefit in cardiovascular disease will be considered, while the challenges of developing drugs against these master cellular regulators will be discussed.

PI3Kγ (Phosphoinositide 3-Kinase γ) Regulates Vascular Smooth Muscle Cell Phenotypic Modulation and Neointimal Formation Through CREB (Cyclic AMP-Response Element Binding Protein)/YAP (Yes-Associated Protein) Signaling

Objective- Vascular smooth muscle cells (VSMCs) phenotype modulation is critical for the resolution of vascular injury. Genetic and pharmacological inhibition of PI3Kγ (phosphoinositide 3-kinase γ) exerts anti-inflammatory and protective effects in multiple cardiovascular diseases. This study investigated the role of PI3Kγ and its downstream effector molecules in the regulation of VSMC phenotypic modulation and neointimal formation in response to vascular injury. Approach and Results- Increased expression of PI3Kγ was found in injured vessel wall as well in cultured, serum-activated wild-type VSMCs, accompanied by a reduction in the expression of calponin and SM22α, 2 differentiation markers of VSMCs. However, the injury-induced downregulation of calponin and SM22α was profoundly attenuated in PI3Kγ^-/- mice. Pharmacological inhibition and short hairpin RNA knockdown of PI3Kγ (PI3Kγ-KD) markedly attenuated YAP (Yes-associated protein) expression and CREB (cyclic AMP-response element binding protein) activation but improved the downregulation of differentiation genes in cultured VSMCs accompanied by reduced cell proliferation and migration. Mechanistically, activated CREB upregulated YAP transcriptional expression through binding to its promoter. Ectopic expression of YAP strikingly repressed the expression of differentiation genes even in PI3Kγ-KD VSMCs. Moreover, established carotid artery ligation and chimeric mice models demonstrate that deletion of PI3Kγ in naïve PI3Kγ^-/- mice as well as in chimeric mice lacking PI3Kγ either in bone marrow or vascular wall significantly reduced neointimal formation after injury. Conclusions- PI3Kγ controls phenotypic modulation of VSMCs by regulating transcription factor CREB activation and YAP expression. Modulating PI3Kγ signaling on local vascular wall may represent a new therapeutic approach to treat proliferative vascular disease.

Function, Regulation and Biological Roles of PI3Kγ Variants

Phosphatidylinositide 3-kinase (PI3K) γ is the only class IB PI3K member playing significant roles in the G-protein-dependent regulation of cell signaling in health and disease. Originally found in the immune system, increasing evidence suggest a wide array of functions in the whole organism. PI3Kγ occur as two different heterodimeric variants: PI3Kγ (p87) and PI3Kγ (p101), which share the same p110γ catalytic subunit but differ in their associated non-catalytic subunit. Here we concentrate on specific PI3Kγ features including its regulation and biological functions. In particular, the roles of its non-catalytic subunits serving as the main regulators determining specificity of class IB PI3Kγ enzymes are highlighted.

For Better or Worse: The Potential for Dose Limiting the On-Target Toxicity of PI 3-Kinase Inhibitors

The hyper-activation of the phosphoinositide (PI) 3-kinase signaling pathway is a hallmark of many cancers and overgrowth syndromes, and as a result, there has been intense interest in the development of drugs that target the various isoforms of PI 3-kinase. Given the key role PI 3-kinases play in many normal cell functions, there is significant potential for the disruption of essential cellular functions by PI 3-kinase inhibitors in normal tissues; so-called on-target drug toxicity. It is, therefore, no surprise that progress within the clinical development of PI 3-kinase inhibitors as single-agent anti-cancer therapies has been slowed by the difficulty of identifying a therapeutic window. The aim of this review is to place the cellular, tissue and whole-body effects of PI 3-kinase inhibition in the context of understanding the potential for dose limiting on-target toxicities and to introduce possible strategies to overcome these.

Synthesis of a 6-Aza-Isoindolinone-Based Inhibitor of Phosphoinositide 3-Kinase γ via Ruthenium-Catalyzed [2 + 2 + 2] Cyclotrimerization

Phosphoinositide 3-kinase (PI3Kγ) is a drug target that has been implicated in the treatment of a range of diseases. We have developed a synthesis of a novel PI3Kγ inhibitor containing a 1,2-dihydro-3H-pyrrolo[3,4-c]pyridin-3-one scaffold. The key step in the synthesis involved a ruthenium-catalyzed [2 + 2 + 2] cyclotrimerization reaction between a diyne and an alkoxycarbonyl isocyanate, a previously unreported coupling partner in such a reaction.

Vitamin E: Regulatory Role on Signal Transduction

Vitamin E modulates signal transduction pathways by several molecular mechanisms. As a hydrophobic molecule located mainly in membranes it contributes together with other lipids to the physical and structural characteristics such as membrane stability, curvature, fluidity, and the organization into microdomains (lipid rafts). By acting as the main lipid-soluble antioxidant, it protects other lipids such as mono- and poly-unsaturated fatty acids (MUFA and PUFA, respectively) against chemical reactions with reactive oxygen and nitrogen species (ROS and RNS, respectively) and prevents membrane destabilization and cellular dysfunction. In cells, vitamin E affects signaling in redox-dependent and redox-independent molecular mechanisms by influencing the activity of enzymes and receptors involved in modulating specific signal transduction and gene expression pathways. By protecting and preventing depletion of MUFA and PUFA it indirectly enables regulatory effects that are mediated by the numerous lipid mediators derived from these lipids. In recent years, some vitamin E metabolites have been observed to affect signal transduction and gene expression and their relevance for the regulatory function of vitamin E is beginning to be elucidated. In particular, the modulation of the CD36/FAT scavenger receptor/fatty acids transporter by vitamin E may influence many cellular signaling pathways relevant for lipid homeostasis, inflammation, survival/apoptosis, angiogenesis, tumorigenesis, neurodegeneration, and senescence. Thus, vitamin E has an important role in modulating signal transduction and gene expression pathways relevant for its uptake, distribution, metabolism, and molecular action that when impaired affect physiological and patho-physiological cellular functions relevant for the prevention of a number of diseases. © 2018 IUBMB Life, 71(4):456-478, 2019.

Hypoxia-Inducible Factor 1 alpha (HIF-1α)/Vascular Endothelial Growth Factor (VEGF) Pathway Participates in Angiogenesis of Myocardial Infarction in Muscone-Treated Mice: Preliminary Study

BACKGROUND Angiogenesis plays a crucial role in myocardial infarction (MI) treatment by ameliorating myocardial remodeling, thus improving cardiac function and preventing heart failure. Muscone has been reported to have beneficial effects on cardiac remodeling in MI mice. However, the effects of muscone on angiogenesis in MI mice and its underlying mechanisms remain unknown. MATERIAL AND METHODS Mice were randomly divided into sham, MI, and MI+muscone groups. The MI mouse model was established by ligating the left anterior descending coronary artery. Mice in the sham group received the same procedure except for ligation. Mice were administered muscone or an equivalent volume of saline for 4 consecutive weeks. Cardiac function was evaluated by echocardiograph after MI for 2 and 4 weeks. Four weeks later, all mice were sacrificed and Masson's trichrome staining was used to assess myocardial fibrosis. Isolectin B4 staining was applied to evaluate the angiogenesis in mouse hearts. Immunohistochemistry, Western blot analysis, and quantitative real-time polymerase chain reaction (qPCR) were performed to analyze expression levels of HIF-1a and its downstream genes. RESULTS Compared with the MI group, muscone treatment significantly improved cardiac function and reduced myocardial fibrosis. Moreover, muscone enhanced angiogenesis in the peri-infarct region and p-VEGFR2 expression in the vascular endothelial cells. Western blot analysis and qPCR showed that muscone upregulated expression levels of HIF-1a and VEGFA. CONCLUSIONS Muscone improved cardiac function in MI mice through augmented angiogenesis. The potential mechanism of muscone treatment in regulating angiogenesis of MI mice was upregulating expression levels of HIF-1α and VEGFA.

Targeting the immunity protein kinases for immuno-oncology

With the rise of immuno-oncology, small-molecule modulators targeting immune system and inflammatory processes are becoming a research hotspot. This work mainly focuses on key kinases acting as central nodes in immune signaling pathways. Although over thirty small-molecule kinase inhibitors have been approved by FDA for the treatment of various cancers, only a few are associated with immuno-oncology. With the going deep of the research work, more and more immunity protein kinase inhibitors are approved for clinical trials to treat solid tumors and hematologic malignancies by FDA, which remain good prospects. Meanwhile, in-depth understanding of biological function of immunity protein kinases in immune system is pushing the field forward. This article focuses on the development of safe and effective small-molecule immunity protein kinase inhibitors and further work needs to keep the promises of these inhibitors for patients' welfare.

8e Protects against Acute Cerebral Ischemia by Inhibition of PI3Kγ-Mediated Superoxide Generation in Microglia

The inflammatory response mediated by microglia plays a critical role in the progression of ischemic stroke. Phosphoinositide 3-kinase gamma (PI3Kγ) has been implicated in multiple inflammatory and autoimmune diseases, making it a promising target for therapeutic intervention. The aim of this study was to evaluate the efficacy of 8e, a hydrogen sulfide (H₂S) releasing derivative of 3-n-butylphthalide (NBP), on brain damage and PI3Kγ signaling following cerebral ischemia injury. 8e significantly reduced sensorimotor deficits, focal infarction, brain edema and neural apoptosis at 72 h after transient middle cerebral artery occlusion (tMCAO). The NOX2 isoform of the NADPH oxidase family is considered a major enzymatic source of superoxide. We found that the release of superoxide, together with the expression of NOX2 subunits p47^phox, p-p47^phox, and the upstream PI3Kγ/AKT signaling were all down-regulated by 8e, both in the penumbral region of the rat brain and in the primary cultured microglia subjected to oxygen-glucose deprivation (OGD). With the use of siRNA and pharmacological inhibitors, we further demonstrated that 8e regulates the formation of superoxide in activated microglia through the PI3Kγ/AKT/NOX2 signaling pathway and subsequently prevents neuronal death in neighboring neurons. Our experimental data indicate that 8e is a potential candidate for the treatment of ischemic stroke and PI3Kγ-mediated neuroinflammation.

Design and Synthesis of a Novel Series of Orally Bioavailable, CNS-Penetrant, Isoform Selective Phosphoinositide 3-Kinase γ (PI3Kγ) Inhibitors with Potential for the Treatment of Multiple Sclerosis (MS)

The lipid kinase phosphoinositide 3-kinase γ (PI3Kγ) has attracted attention as a potential target to treat a variety of autoimmune disorders, including multiple sclerosis, due to its role in immune modulation and microglial activation. By minimizing the number of hydrogen bond donors while targeting a previously uncovered selectivity pocket adjacent to the ATP binding site of PI3Kγ, we discovered a series of azaisoindolinones as selective, brain penetrant inhibitors of PI3Kγ. This ultimately led to the discovery of 16, an orally bioavailable compound that showed efficacy in murine experimental autoimmune encephalomyelitis (EAE), a preclinical model of multiple sclerosis.

Identification of a Potent, Selective, and Efficacious Phosphatidylinositol 3-Kinase δ (PI3Kδ) Inhibitor for the Treatment of Immunological Disorders

PI3Kδ plays an important role controlling immune cell function and has therefore been identified as a potential target for the treatment of immunological disorders. This article highlights our work toward the identification of a potent, selective, and efficacious PI3Kδ inhibitor. Through careful SAR, the successful replacement of a polar pyrazole group by a simple chloro or trifluoromethyl group led to improved Caco-2 permeability, reduced Caco-2 efflux, reduced hERG PC activity, and increased selectivity profile while maintaining potency in the CD69 hWB assay. The optimization of the aryl substitution then identified a 4'-CN group that improved the human/rodent correlation in microsomal metabolic stability. Our lead molecule is very potent in PK/PD assays and highly efficacious in a mouse collagen-induced arthritis model.

Ghrelin Promotes Functional Angiogenesis in a Mouse Model of Critical Limb Ischemia Through Activation of Proangiogenic MicroRNAs

Current therapeutic strategies for the treatment of critical limb ischemia (CLI) have only limited success. Recent in vitro evidence in the literature, using cell lines, proposes that the peptide hormone ghrelin may have angiogenic properties. In this study, we aim to investigate if ghrelin could promote postischemic angiogenesis in a mouse model of CLI and, further, identify the mechanistic pathway(s) that underpin ghrelin's proangiogenic properties. CLI was induced in male CD1 mice by femoral artery ligation. Animals were then randomized to receive either vehicle or acylated ghrelin (150 μg/kg sc) for 14 consecutive days. Subsequently, synchrotron radiation microangiography was used to assess hindlimb perfusion. Subsequent tissue samples were collected for molecular and histological analysis. Ghrelin treatment markedly improved limb perfusion by promoting the generation of new capillaries and arterioles (internal diameter less than 50 μm) within the ischemic hindlimb that were both structurally and functionally normal; evident by robust endothelium-dependent vasodilatory responses to acetylcholine. Molecular analysis revealed that ghrelin's angiogenic properties were linked to activation of prosurvival Akt/vascular endothelial growth factor/Bcl-2 signaling cascade, thus reducing the apoptotic cell death and subsequent fibrosis. Further, ghrelin treatment activated proangiogenic (miR-126 and miR-132) and antifibrotic (miR-30a) microRNAs (miRs) while inhibiting antiangiogenic (miR-92a and miR-206) miRs. Importantly, in vitro knockdown of key proangiogenic miRs (miR-126 and miR-132) inhibited the angiogenic potential of ghrelin. These results therefore suggest that clinical use of ghrelin for the early treatment of CLI may be a promising and potent inducer of reparative vascularization through modulation of key molecular factors.

LY294002 prevents lipopolysaccharide‑induced hepatitis in a murine model by suppressing IκB phosphorylation

Although fulminant hepatitis represents a ubiquitous human health problem, there is a lack of effective therapeutic strategies that have few side‑effects and the precise mechanisms underlying fulminant hepatitis are not fully understood. Phosphoinositide 3‑kinase (PI3K) is a pivotal kinase known to regulate inflammatory responses in hepatic diseases. Although previous research indicates that PI3K is involved in cardiac diseases, including myocardial infarction, it currently remains unclear whether the inhibition of PI3K is essential for ameliorating the severity of lipopolysaccharide (LPS)‑induced hepatitis. The aim of the present study was to investigate whether pharmacological blockade of PI3K ameliorates the development of LPS‑induced murine acute hepatic injury. A murine model of LPS‑induced acute hepatic injury was used to investigate the therapeutic effect of the pan‑PI3K inhibitor, LY294002 on murine fulminant hepatitis and to investigate potential underlying mechanisms. The current report presents the in vivo role of LY294002 in protecting the mice from fulminant hepatitis. LY294002 was observed to exert significant protective effects on the liver by reducing the activities of alanine aminotransferase and aspartate aminotransferase, as well as by improving the histological architecture of the liver. In LPS‑induced hepatitis, treatment with LY294002 clearly inhibited intrahepatic synthesis of various disease‑relevant proinflammatory cytokines, including tumor necrosis factor‑α, interleukin (IL)‑6, IL‑1β and interferon‑γ. Furthermore, LY294002 was observed to significantly inhibit IκB phosphorylation in LPS‑injured mouse liver samples. Therefore, LY294002 may protect the liver from LPS‑induced injury by inhibition of the IκB‑nuclear factor κ‑light‑chain‑enhancer of activated B cell dependent signaling pathway. Thus, the current report provides evidence that LY294002 exerts potent effects against LPS‑induced hepatic injury, indicating its potential therapeutic value for the treatment of acute hepatitis.

Diazoxide protects L6 skeletal myoblasts from H2O2-induced apoptosis via the phosphatidylinositol-3 kinase/Akt pathway

OBJECTIVES AND DESIGN

Transplanted cell survival might greatly improve the therapeutic efficacy of cell therapy. Diazoxide (DZ), a highly selective mitochondrial ATP-sensitive potassium channel opener, is known to suppress cell apoptosis and protect cells in oxidative stressed ischemic environment. We explored the mechanisms involved in DZ pre-treatment-induced anti-apoptotic effect on L6 skeletal myoblast (SKM).

MATERIALS AND METHODS

L6 SKMs were divided into control group, H2O2 group, DZ + H2O2 group and DZ + LY + H2O2 group. Treatments of 400 μmol/L H2O2 for 24 h alone, or after 200 μmol/L DZ pre-treatment for 30 min, or after DZ and 50 μmol/L LY294002 co-administration for 30 min were performed. The cell apoptosis rates were assessed by flow cytometric analysis. The changes of mitochondrial membrane potential were determined by JC-1 mitochondrial staining. The activation of phosphatidylinositol-3 kinase (PI3K)/Akt, caspase-9 and caspase-3 was detected by western blot.

RESULTS

Compared with the H2O2 group, DZ pre-treatment protected cells from H2O2-induced damage, increased Akt phosphorylation, prevented mitochondrial membrane depolarization as well as the activation of caspase-9 and caspase-3 and decreased the cell apoptosis rate. However, the DZ-induced cytoprotective and anti-apoptosis effects were partly inhibited by co-administration of a PI3K inhibitor, LY294002.

CONCLUSIONS

These data suggest that DZ pre-treatment contributes to protection of L6 SKMs against apoptosis at least partly by activating the PI3K/Akt pathway and subsequently inhibiting the mitochondrial-mediated caspase-dependent apoptotic signalling pathway.

OSM Enhances Angiogenesis and Improves Cardiac Function after Myocardial Infarction

Oncostatin M (OSM) has been reported to stimulate angiogenesis by upregulating VEGF and bFGF, implying that it could be a therapeutic strategy in treating ischemic diseases. The present study was aimed at investigating whether OSM could improve cardiac function via prompting angiogenesis following myocardial infarction (MI). Wild type (WT) and Oβ knock-out (Oβ^−/−) mice were, respectively, randomized into sham group, MI + vehicle group, and MI + OSM group. WT mice displayed significantly impaired cardiac function after MI. OSM treatment attenuated cardiac dysfunction in WT MI mice, while Oβ deletion abrogated the protective effects. Besides, OSM attenuated heart hypertrophy and pulmonary congestion evidenced by decreased heart weight/body weight and lung weight/body weight ratio. Further, reduction of apoptosis and fibrosis in infarct border zone was observed in OSM treated WT MI mice compared with vehicle. Moreover, in WT mice subjected to MI, OSM treatment significantly increased capillary density along with upregulation of p-Akt and angiogenic factors VEGF and bFGF in comparison with vehicle, and this phenomenon was not found in Oβ^−/− mice. In conclusion, OSM treatment preserved cardiac function, inhibited apoptosis and fibrosis, and stimulated angiogenesis via upregulating VEGF and bFGF in infarct border zone of ischemic myocardium, indicating that OSM could be a novel therapeutic target for MI.

The influence of dysfunctional signaling and lipid homeostasis in mediating the inflammatory responses during atherosclerosis

Atherosclerosis, the underlying cause of myocardial infarction and thrombotic cerebrovascular events, is responsible for the majority of deaths in westernized societies. Mortality from this disease is also increasing at a marked rate in developing countries due to the acquisition of a westernized lifestyle accompanied with elevated rates of obesity and diabetes. Atherosclerosis is recognized as a chronic inflammatory disorder associated with lipid accumulation and the development of fibrotic plaques within the walls of medium and large arteries. A range of immune cells, such as macrophages and T-lymphocytes, through the action of various cytokines, such as interleukins-1 and -33, transforming growth factor-β and interferon-γ, orchestrates the inflammatory response in this disease. The disease is also characterized by marked dysfunction in lipid homeostasis and signaling pathways that control the inflammatory response. This review will discuss the molecular basis of atherosclerosis with particular emphasis on the roles of the immune cells and cytokines along with the dysfunctional lipid homeostasis and cell signaling associated with this disease.

Discovery of fluoroquinolone derivatives as potent, selective inhibitors of PI3Kγ

A new class of fluoroquinolone derivatives having improved potency toward PI3K was designed through a docking study.

Dipeptidyl peptidase-4 inhibitors and their effects on the cardiovascular system

It is well known that patients with type 2 diabetes mellitus (T2DM) are at increased risk of cardiovascular (CV) disease. Elevated plasma glucose levels that independently lead to increased cardiovascular risk, combined with associated co-morbidities such as obesity, hypertension, and dyslipidemia, further contribute to the development of CV complications. Dipeptidyl peptidase 4 inhibitors (DPP-4 inhibitors) are a relatively new class of drugs used for the treatment of diabetes and recently have been widely used in clinical practice. They exert their actions through degradation inhibition of endogenous glucagon-like peptides (GLP-1) and glucose-dependent insulinotropic peptides (GIP), with a resulting increase in glucose mediated insulin secretion and a suppression of glucagon secretion. Since GLP-1 is known to have an impact not only on plasma glucose levels but also to have cardiovascular protective effects there is increased speculation of whether DPP-4 inhibitors will have similar effects. Though many short-term studies have been encouraging, ongoing long-term clinical trials on humans are needed to provide further clarity to the complete safety profiles of these agents in terms of cardiovascular risk, and whether they may exert potential cardiovascular benefit. This review includes available data on the cardiovascular effects of DPP-4 inhibitors as well as their overall safety profile.

Anti-inflammatory strategies for ventricular remodeling following ST-segment elevation acute myocardial infarction

Acute myocardial infarction (AMI) leads to molecular, structural, geometric, and functional changes in the heart in a process known as ventricular remodeling. An intense organized inflammatory response is triggered after myocardial ischemia and necrosis and involves all components of the innate immunity, affecting both cardiomyocytes and noncardiomyocyte cells. Inflammation is triggered by tissue injury; it mediates wound healing and scar formation and affects ventricular remodeling. Many therapeutic attempts aimed at reducing inflammation in AMI during the past 3 decades presented issues of impaired healing or increased risk of cardiac rupture or failed to show any additional benefit in addition to standard therapies. More recent strategies aimed at selectively blocking one of the key factors upstream rather than globally suppressing the response downstream have shown some promising results in pilot trials. We herein review the pathophysiological mechanisms of inflammation and ventricular remodeling after AMI and the results of clinical trials with anti-inflammatory strategies.

Sonic hedgehog mediates a novel pathway of PDGF-BB-dependent vessel maturation

Recruitment of mural cells (MCs), namely pericytes and smooth muscle cells (SMCs), is essential to improve the maturation of newly formed vessels. Sonic hedgehog (Shh) has been suggested to promote the formation of larger and more muscularized vessels, but the underlying mechanisms of this process have not yet been elucidated. We first identified Shh as a target of platelet-derived growth factor BB (PDGF-BB) and found that SMCs respond to Shh by upregulating extracellular signal-regulated kinase 1/2 and Akt phosphorylation. We next showed that PDGF-BB-induced SMC migration was reduced after inhibition of Shh or its signaling pathway. Moreover, we found that PDGF-BB-induced SMC migration involves Shh-mediated motility. In vivo, in the mouse model of corneal angiogenesis, Shh is expressed by MCs of newly formed blood vessels. PDGF-BB inhibition reduced Shh expression, demonstrating that Shh is a target of PDGF-BB, confirming in vitro experiments. Finally, we found that in vivo inhibition of either PDGF-BB or Shh signaling reduces NG2(+) MC recruitment into neovessels and subsequently reduces neovessel life span. Our findings demonstrate, for the first time, that Shh is involved in PDGF-BB-induced SMC migration and recruitment of MCs into neovessels and elucidate the molecular signaling pathway involved in this process.

Postischemic revascularization: from cellular and molecular mechanisms to clinical applications

After the onset of ischemia, cardiac or skeletal muscle undergoes a continuum of molecular, cellular, and extracellular responses that determine the function and the remodeling of the ischemic tissue. Hypoxia-related pathways, immunoinflammatory balance, circulating or local vascular progenitor cells, as well as changes in hemodynamical forces within vascular wall trigger all the processes regulating vascular homeostasis, including vasculogenesis, angiogenesis, arteriogenesis, and collateral growth, which act in concert to establish a functional vascular network in ischemic zones. In patients with ischemic diseases, most of the cellular (mainly those involving bone marrow-derived cells and local stem/progenitor cells) and molecular mechanisms involved in the activation of vessel growth and vascular remodeling are markedly impaired by the deleterious microenvironment characterized by fibrosis, inflammation, hypoperfusion, and inhibition of endogenous angiogenic and regenerative programs. Furthermore, cardiovascular risk factors, including diabetes, hypercholesterolemia, hypertension, diabetes, and aging, constitute a deleterious macroenvironment that participates to the abrogation of postischemic revascularization and tissue regeneration observed in these patient populations. Thus stimulation of vessel growth and/or remodeling has emerged as a new therapeutic option in patients with ischemic diseases. Many strategies of therapeutic revascularization, based on the administration of growth factors or stem/progenitor cells from diverse sources, have been proposed and are currently tested in patients with peripheral arterial disease or cardiac diseases. This review provides an overview from our current knowledge regarding molecular and cellular mechanisms involved in postischemic revascularization, as well as advances in the clinical application of such strategies of therapeutic revascularization.

Mechanistic target of rapamycin complex 2 protects the heart from ischemic damage

BACKGROUND

The mechanistic target of rapamycin (mTOR) comprises 2 structurally distinct multiprotein complexes, mTOR complexes 1 and 2 (mTORC1 and mTORC2). Deregulation of mTOR signaling occurs during and contributes to the severity of myocardial damage from ischemic heart disease. However, the relative roles of mTORC1 versus mTORC2 in the pathogenesis of ischemic damage are unknown.

METHODS AND RESULTS

Combined pharmacological and molecular approaches were used to alter the balance of mTORC1 and mTORC2 signaling in cultured cardiac myocytes and in mouse hearts subjected to conditions that mimic ischemic heart disease. The importance of mTOR signaling in cardiac protection was demonstrated by pharmacological inhibition of both mTORC1 and mTORC2 with Torin1, which led to increased cardiomyocyte apoptosis and tissue damage after myocardial infarction. Predominant mTORC1 signaling mediated by suppression of mTORC2 with Rictor similarly increased cardiomyocyte apoptosis and tissue damage after myocardial infarction. In comparison, preferentially shifting toward mTORC2 signaling by inhibition of mTORC1 with PRAS40 led to decreased cardiomyocyte apoptosis and tissue damage after myocardial infarction.

CONCLUSIONS

These results suggest that selectively increasing mTORC2 while concurrently inhibiting mTORC1 signaling is a novel therapeutic approach for the treatment of ischemic heart disease.

Xenon and isoflurane reduce left ventricular remodeling after myocardial infarction in the rat

BACKGROUND

Xenon and isoflurane are known to have cardioprotective properties. We tested the hypothesis that these anesthetics positively influence myocardial remodeling 28 days after experimental perioperative myocardial infarction and compared their effects.

METHODS

A total of 60 male Sprague-Dawley rats were subjected to 60 min of coronary artery occlusion and 120 min of reperfusion. Prior to ischemia, the animals were randomized for the different narcotic regimes (0.6 vol% isoflurane, 70 vol% xenon, or intraperitoneal injection of s-ketamine). Acute injury was quantified by echocardiography and troponin I. After 4 weeks, left ventricular function was assessed by conductance catheter to quantify hemodynamic compromise. Cardiac remodeling was characterized by quantification of dilatation, hypertrophy, fibrosis, capillary density, apoptosis, and expression of fetal genes (α/β myosin heavy chains, α-skeletal actin, periostin, and sarco/endoplasmic reticulum Ca2+-ATPase).

RESULTS

Whereas xenon and isoflurane impeded the acute effects of ischemia-reperfusion on hemodynamics and myocardial injury at a comparable level, differences were found after 4 weeks. Xenon in contrast to isoflurane or ketamine anesthetized animals demonstrated a lower remodeling index (0.7 ± 0.1 vs. 0.9 ± 0.3 and 1.0 ± 0.3g/ml), better ejection fraction (62 ± 9 vs. 49 ± 7 and 35 ± 6%), and reduced expression of β-myosin heavy chain and periostin. The effects on hypertrophy, fibrosis, capillary density, and apoptosis were comparable.

CONCLUSIONS

Compared to isoflurane and s-ketamine, xenon limited progressive adverse cardiac remodeling and contractile dysfunction 28 days after perioperative myocardial infarction.

Protective effect of erythropoietin on renal injury induced in rats by four weeks of exhaustive exercise

Background

The protective effect of Erythropoietin (EPO) analogue rHuEPO on acute renal injury induced by exhaustive exercise had been reported. The purpose of this study is to probe into the protective effect of EPO on chronic renal injury induced by repeated exhaustive exercise for four weeks.

Methods

Eighty adult male Sprague–Dawley rats were used in this experiment. The animals were randomly allocated to one of four groups: control (C), exhaustive exercise test (ET), ET plus EPO pre-treatement (ET+EPO) and ET+EPO plus LY294002 pretreatment (ET+EPO+LY).

Results

Compared with the rats in control group, there was considerable damage in kidney cells in rats of ET group as revealed by histological and ultrastructural examinations. However, treatment with EPO during the training, the exhaustive running distance was significant increased (P < 0.01), and the pathological changes of kidney cell were much less compared with those of rats without EPO intervention. When LY294002, a specific inhibitor of phospholipids phthalocyanine inositol 3-kinase, was added to the EPO treated rats, the injury changes of renal cell were becoming more pronounced.

Conclusions

The protective effect of EPO on chronic renal injury induced by repeated exhaustive exercise was demonstrated in the present study. We proposed that the effect could be due to inhibiting the cell apoptosis and blocking the formation of interstitial fibrosis via activation of the PI3K/Akt pathway, thus plays role in the endogenous protection of the kidney injury.

Therapeutic applications of PI3K inhibitors in cardiovascular diseases

PI3Ks are signaling enzymes engaged by different types of membrane receptors and activated in cardiovascular diseases such as hypertension, atherosclerosis, thrombosis and heart failure. Studies performed on genetically modified animals have provided proof-of-concept that general or isoform-specific blockade of these enzymes can modify disease development and progression. Hence, therapeutic inhibition of PI3Ks with novel pharmacological compounds constitutes a promising area of drug development. In particular, inhibitors of PI3Ks have the potential to reduce blood pressure, restrain the development of atherosclerosis and/or stabilize atherosclerotic plaques, blunt platelet aggregation, prevent left ventricular remodeling and preserve myocardial contractility in heart failure. This review summarizes the rationale of PI3K inhibition in the most prevalent cardiovascular diseases, and the available data on the therapeutic effects of PI3K inhibitors in their preclinical models. Implications for future drug development and human therapy are also discussed.

Phosphoinositide 3-kinase γ inhibits cardiac GSK-3 independently of Akt

Activation of cardiac phosphoinositide 3-kinase α (PI3Kα) by growth factors, such as insulin, or activation of PI3Kγ downstream of heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors stimulates the activity of the kinase Akt, which phosphorylates and inhibits glycogen synthase kinase-3 (GSK-3). We found that PI3Kγ inhibited GSK-3 independently of the insulin-PI3Kα-Akt axis. Although insulin treatment activated Akt in PI3Kγ knockout mice, phosphorylation of GSK-3 was decreased compared to control mice. GSK-3 is activated when dephosphorylated by the protein phosphatase 2A (PP2A), which is activated when methylated by the PP2A methyltransferase PPMT-1. PI3Kγ knockout mice showed increased activity of PPMT-1 and PP2A and enhanced nuclear export of the GSK-3 substrate NFATc3. GSK-3 inhibits cardiac hypertrophy, and the hearts of PI3Kγ knockout mice were smaller compared to those of wild-type mice. Cardiac overexpression of a catalytically inactive PI3Kγ (PI3Kγ(inact)) transgene in PI3Kγ knockout mice reduced the activities of PPMT-1 and PP2A and increased phosphorylation of GSK-3. Furthermore, PI3Kγ knockout mice expressing the PI3Kγ(inact) transgene had larger hearts than wild-type or PI3Kγ knockout mice. Our studies show that a kinase-independent function of PI3Kγ could directly inhibit GSK-3 function by preventing the PP2A-PPMT-1 interaction and that this inhibition of GSK-3 was independent of Akt.

Inhibition of anti-apoptotic signals by Wortmannin induces apoptosis in the remote myocardium after LAD ligation: evidence for a protein kinase C-δ-dependent pathway

It has been shown that, in the remote myocardium after infarction (MI), protein kinase C (PKC) inhibition reduces apoptosis both by blocking proapoptotic pathways and by activating antiapoptotic signals including the Akt pathway. However, it was open if vice versa, blockade of antiapoptotic pathways may influence proapoptotic signals. To clarify this, the present study tested the effects of the PI3-kinase blocker Wortmannin on proapoptotic signals and on apoptosis execution in the remote myocardium after infarction. Rats were subjected to MI by LAD ligation in situ. Some were pre-treated with Wortmannin alone or in combination with the PKC inhibitor Chelerythrine. After 24 h, pro- and anti-apoptotic signals (caspase-3, PKC isoforms, p38-MAPK, p42/44-MAPK, Akt, Bad), and marker of apoptosis execution (TUNEL) were quantified in the myocardium remote from the infarction. Wortmannin treatment increased apoptosis in the remote myocardium both at baseline and after MI, together with an activation of the PKC-δ/p38-MAPK-pathway. PKC-ε and p42/44-MAPK were unaffected. Combined treatment with Wortmannin and Chelerythrine fully reversed the pro-apoptotic effects of Wortmannin both at baseline and after MI. The PKC-δ-p38-MAPK-pathway as a strong signal for apoptosis in the non-infarcted myocardium can be influenced by targeting the anti-apoptotic PI3-kinase pathway. This gives evidence of a bi-directional crosstalk of pro- and anti-apoptotic signals after infarction.