Cyclophilin A is required for angiotensin II-induced p47phox translocation to caveolae in vascular smooth muscle cells

Circ_005077 accelerates myocardial lipotoxicity induced by high-fat diet via CyPA/p47PHOX mediated ferroptosis

The long-term high-fat diet (HFD) can cause myocardial lipotoxicity, which is characterized pathologically by myocardial hypertrophy, fibrosis, and remodeling and clinically by cardiac dysfunction and heart failure in patients with obesity and diabetes. Circular RNAs (circRNAs), a novel class of noncoding RNA characterized by a ring formation through covalent bonds, play a critical role in various cardiovascular diseases. However, few studies have been conducted to investigate the role and mechanism of circRNA in myocardial lipotoxicity. Here, we found that circ_005077, formed by exon 2-4 of Crmp1, was significantly upregulated in the myocardium of an HFD-fed rat. Furthermore, we identified circ_005077 as a novel ferroptosis-related regulator that plays a role in palmitic acid (PA) and HFD-induced myocardial lipotoxicity in vitro and in vivo. Mechanically, circ_005077 interacted with Cyclophilin A (CyPA) and inhibited its degradation via the ubiquitination proteasome system (UBS), thus promoting the interaction between CyPA and p47phox to enhance the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase responsible for ROS generation, subsequently inducing ferroptosis. Therefore, our results provide new insights into the mechanisms of myocardial lipotoxicity, potentially leading to the identification of a novel therapeutic target for the treatment of myocardial lipotoxicity in the future.

Inhibitors of Cyclophilin A: Current and Anticipated Pharmaceutical Agents for Inflammatory Diseases and Cancers

Cyclophilin A, a widely prevalent cellular protein, exhibits peptidyl-prolyl cis-trans isomerase activity. This protein is predominantly located in the cytosol; additionally, it can be secreted by the cells in response to inflammatory stimuli. Cyclophilin A has been identified to be a key player in many of the biological events and is therefore involved in several diseases, including vascular and inflammatory diseases, immune disorders, aging, and cancers. It represents an attractive target for therapeutic intervention with small molecule inhibitors such as cyclosporin A. Recently, a number of novel inhibitors of cyclophilin A have emerged. However, it remains elusive whether and how many cyclophilin A inhibitors function in the inflammatory diseases and cancers. In this review, we discuss current available data about cyclophilin A inhibitors, including cyclosporin A and its derivatives, quinoxaline derivatives, and peptide analogues, and outline the most recent advances in clinical trials of these agents. Inhibitors of cyclophilin A are poised to enhance our comprehension of the molecular mechanisms that underpin inflammatory diseases and cancers associated with cyclophilin A. This advancement will aid in the development of innovative pharmaceutical treatments in the future.

Signaling pathways in vascular function and hypertension: molecular mechanisms and therapeutic interventions

Hypertension is a global public health issue and the leading cause of premature death in humans. Despite more than a century of research, hypertension remains difficult to cure due to its complex mechanisms involving multiple interactive factors and our limited understanding of it. Hypertension is a condition that is named after its clinical features. Vascular function is a factor that affects blood pressure directly, and it is a main strategy for clinically controlling BP to regulate constriction/relaxation function of blood vessels. Vascular elasticity, caliber, and reactivity are all characteristic indicators reflecting vascular function. Blood vessels are composed of three distinct layers, out of which the endothelial cells in intima and the smooth muscle cells in media are the main performers of vascular function. The alterations in signaling pathways in these cells are the key molecular mechanisms underlying vascular dysfunction and hypertension development. In this manuscript, we will comprehensively review the signaling pathways involved in vascular function regulation and hypertension progression, including calcium pathway, NO-NOsGC-cGMP pathway, various vascular remodeling pathways and some important upstream pathways such as renin-angiotensin-aldosterone system, oxidative stress-related signaling pathway, immunity/inflammation pathway, etc. Meanwhile, we will also summarize the treatment methods of hypertension that targets vascular function regulation and discuss the possibility of these signaling pathways being applied to clinical work.

Activation of the Mas receptors by AVE0991 and MrgD receptor using alamandine to limit the deleterious effects of Ang II-induced hypertension

The MrgD receptor agonist, alamandine (ALA) and Mas receptor agonist, AVE0991 have recently been identified as protective components of the renin-angiotensin system. We evaluated the effects of ALA and AVE0991 on cardiovascular function and remodeling in angiotensin (Ang) II-induced hypertension in rats. Sprague Dawley rats were subject to 4-week subcutaneous infusions of Ang II (80 ng/kg/min) or saline after which they were treated with ALA (50 μg/kg), AVE0991 (576 μg/kg), or ALA+AVE0991 during the last 2 weeks. Systolic blood pressure (SBP) and heart rate (HR) values were recorded with tail-cuff plethysmography at 1, 15, and 29 days post-treatment. After euthanization, the heart and thoracic aorta were removed for further analysis and vascular responses. SBP significantly increased in the Ang II group when compared to the control group. Furthermore, Ang II also caused an increase in cardiac and aortic cyclophilin-A (CYP-A), monocyte chemoattractant protein-1 (MCP-1), and cardiomyocyte degeneration but produced a decrease in vascular relaxation. HR, matrix metalloproteinase-2 and -9, NADPH oxidase-4, and lysyl oxidase levels were comparable among groups. ALA, AVE0991, and the drug combination produced antihypertensive effects and alleviated vascular responses. The inflammatory and oxidative stress related to cardiac MCP-1 and CYP-A levels decreased in the Ang II+ALA+AVE0991 group. Vascular but not cardiac angiotensin-converting enzyme-2 levels decreased with Ang II administration but were similar to the Ang II+ALA+AVE0991 group. Our experimental data showed the combination of ALA and AVE0991 was found beneficial in Ang II-induced hypertension in rats by reducing SBP, oxidative stress, inflammation, and improving vascular responses.

Cyclosporin A: A Repurposable Drug in the Treatment of COVID-19?

Coronavirus disease 2019 (COVID-19) is now at the forefront of major health challenge faced globally, creating an urgent need for safe and efficient therapeutic strategies. Given the high attrition rates, high costs, and quite slow development of drug discovery, repurposing of known FDA-approved molecules is increasingly becoming an attractive issue in order to quickly find molecules capable of preventing and/or curing COVID-19 patients. Cyclosporin A (CsA), a common anti-rejection drug widely used in transplantation, has recently been shown to exhibit substantial anti-SARS-CoV-2 antiviral activity and anti-COVID-19 effect. Here, we review the molecular mechanisms of action of CsA in order to highlight why this molecule seems to be an interesting candidate for the therapeutic management of COVID-19 patients. We conclude that CsA could have at least three major targets in COVID-19 patients: (i) an anti-inflammatory effect reducing the production of proinflammatory cytokines, (ii) an antiviral effect preventing the formation of the viral RNA synthesis complex, and (iii) an effect on tissue damage and thrombosis by acting against the deleterious action of angiotensin II. Several preliminary CsA clinical trials performed on COVID-19 patients report lower incidence of death and suggest that this strategy should be investigated further in order to assess in which context the benefit/risk ratio of repurposing CsA as first-line therapy in COVID-19 is the most favorable.

Cyclophilin 19 secreted in the host cell cytosol by Trypanosoma cruzi promotes ROS production required for parasite growth

Infection by Trypanosoma cruzi, the protozoan parasite that causes Chagas disease, depends on reactive oxygen species (ROS), which has been described to induce parasite proliferation in mammalian host cells. It is unknown how the parasite manages to increase host ROS levels. Here, we found that intracellular T. cruzi forms release in the host cytosol its major cyclophilin of 19 kDa (TcCyp19). Parasites depleted of TcCyp19 by using CRISPR/Cas9 gene replacement proliferate inefficiently and fail to increase ROS, compared to wild type parasites or parasites with restored TcCyp19 gene expression. Expression of TcCyp19 in L6 rat myoblast increased ROS levels and restored the proliferation of TcCyp19 depleted parasites. These events could also be inhibited by cyclosporin A, (a cyclophilin inhibitor), and by polyethylene glycol-linked to antioxidant enzymes. TcCyp19 was found more concentrated in the membrane leading edges of the host cells in regions that also accumulate phosphorylated p47^phox , as observed to the endogenous cyclophilin A, suggesting some mechanisms involved with the translocation process of the regulatory subunit p47^phox in the activation of the NADPH oxidase enzymatic complex. We concluded that cyclophilin released in the host cell cytosol by T. cruzi mediates the increase of ROS, required to boost parasite proliferation in mammalian hosts.

Extracellular cyclophilin A induces cardiac hypertrophy via the ERK/p47phox pathway

Excessive reactive oxygen species (ROS) are a critical driver of cardiac hypertrophy developing into heart failure. Cyclophilin A (CyPA), a member of the cyclophilin family, has been highlighted as a main secreted ROS-induced factor. The mechanism by which extracellular CyPA interacts with cardiomyocytes is unclear. We showed that extracellular CyPA is upregulated in cardiac hypertrophy rats and expressed around hypertrophic cardiomyocytes. Cell experiments further confirmed that extracellular CyPA induces H9c2 cardiomyocytes hypertrophy via ROS generation. Extracellular CyPA-induced ROS is derived from nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase, and extracellular CyPA activates p47phox membrane translocation through ERK1/2 pathway. When blocking extracellular matrix metalloproteinase inducer (EMMPRIN), most of the extracellular CyPA effects were significantly inhibited. The current study shows that extracellular CyPA is one of the key factors linking oxidative stress and cardiac hypertrophy, and may be a potential target for cardiac hypertrophy therapy.

Role of CyPA in cardiac hypertrophy and remodeling

Pathological cardiac hypertrophy is a complex process and eventually develops into heart failure, in which the heart responds to various intrinsic or external stress, involving increased interstitial fibrosis, cell death and cardiac dysfunction. Studies have shown that oxidative stress is an important mechanism for this maladaptation. Cyclophilin A (CyPA) is a member of the cyclophilin (CyPs) family. Many cells secrete CyPA to the outside of the cells in response to oxidative stress. CyPA from blood vessels and the heart itself participate in a variety of signaling pathways to regulate the production of reactive oxygen species (ROS) and mediate inflammation, promote cardiomyocyte hypertrophy and proliferation of cardiac fibroblasts, stimulate endothelial injury and vascular smooth muscle hyperplasia, and promote the dissolution of extracellular matrix (ECM) by activating matrix metalloproteinases (MMPs). The events triggered by CyPA cause a decline of diastolic and systolic function and finally lead to the occurrence of heart failure. This article aims to introduce the role and mechanism of CyPA in cardiac hypertrophy and remodeling, and highlights its potential role as a disease biomarker and therapeutic target.

Cyclophilin A Protects Cardiomyocytes against Hypoxia/Reoxygenation-Induced Apoptosis via the AKT/Nox2 Pathway

Hypoxia/reoxygenation (H/R) accelerates the process of cardiomyocyte apoptosis during ischemia-reperfusion. Excessive reactive oxygen species (ROS) are a critical driver of oxidative stress injury. Cyclophilin A (CyPA) is a major ROS-induced factor in atherosclerosis. There is a positive feedback mechanism between CyPA and ROS, which enables the oxidative stress response to continue and expand. However, it is unclear whether this positive feedback mechanism exists in cardiomyocytes. Through western blotting and flow cytometric assays and TUNEL assay, we found that CyPA inhibited the apoptosis of H9c2 cardiomyocytes under H/R conditions. By dihydroethidium (DHE) staining and electron spin resonance (ESR) assays, we demonstrated that CyPA reduced ROS production and suppressed O₂⁻ production dependent on reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. By western blotting, we showed that CyPA inhibited the expression of NADPH oxidase 2 (Nox2) protein by the AKT pathway. Through confocal microscopy assay, we found that CyPA reduced the expression of Nox2 membrane-bound subunits. The current study shows that a positive feedback mechanism does not exist in H9c2 cardiomyoblasts. CyPA protects H9c2 cardiomyoblasts against H/R-induced apoptosis via the AKT/Nox2 pathway. This could be a potential target for ischemia-reperfusion injury therapy.

Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT₁R) is believed to mediate most functions of ANG II in the system. AT₁R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT₁R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT₁R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.

Extracellular and Intracellular Cyclophilin A, Native and Post-Translationally Modified, Show Diverse and Specific Pathological Roles in Diseases

CypA (cyclophilin A) is a ubiquitous and highly conserved protein with peptidyl prolyl isomerase activity. Because of its highly abundant level in the cytoplasm, most studies have focused on the roles of CypA as an intracellular protein. However, emerging evidence suggests an important role for extracellular CypA in the pathogenesis of several diseases through receptor (CD147 or other)-mediated autocrine and paracrine signaling pathways. In this review, we will discuss the shared and unique pathological roles of extracellular and intracellular CypA in human cardiovascular diseases. In addition, the evolving role of post-translational modifications of CypA in the pathogenesis of disease is discussed. Finally, recent studies with drugs specific for extracellular CypA show its importance in disease pathogenesis in several animal models and make extracellular CypA a new therapeutic target.

Role of l-amino acid oxidase isolated from Calloselasma rhodostoma venom on neutrophil NADPH oxidase complex activation

The action of Cr-LAAO, an l-amino acid oxidase isolated from Calloselasma rhodosthoma snake venom, on NADPH oxidase activation in isolated human neutrophil function was investigated. This enzyme has an intrinsic activity of hydrogen peroxide production. Cr-LAAO, in its native form, induces the ROS production in neutrophil and migration of cytosolic NADPH oxidase components p40^phox, p47^phox and p67^phox to the membrane, and Rac, a GTPase protein member, with the involvement of intracellular signaling mediated by phospho PKC-α. In its inactive form, iCr-LAAO does not induce NADPH oxidase activation in neutrophil showing that the intrinsic enzymatic activity does not have a role in this process, suggesting that its primary structure is essential for the cell's stimulation. Accordingly, the data showed for the first time that the Cr-LAAO has a role in NADPH oxidase complex activation triggering relevant proinflammatory events in human neutrophils.

Extracellular Matrix Metalloproteinase Inducer EMMPRIN (CD147) in Cardiovascular Disease

The receptor EMMPRIN is involved in the development and progression of cardiovascular diseases and in the pathogenesis of myocardial infarction. There are several binding partners of EMMPRIN mediating the effects of EMMPRIN in cardiovascular diseases. EMMPRIN interaction with most binding partners leads to disease progression by mediating cytokine or chemokine release, the activation of platelets and monocytes, as well as the formation of monocyte-platelet aggregates (MPAs). EMMPRIN is also involved in atherosclerosis by mediating the infiltration of pro-inflammatory cells. There is also evidence that EMMPRIN controls energy metabolism of cells and that EMMPRIN binding partners modulate intracellular glycosylation and trafficking of EMMPRIN towards the cell membrane. In this review, we systematically discuss these multifaceted roles of EMMPRIN and its interaction partners, such as Cyclophilins, in cardiovascular disease.

Human serum albumin and oxidative stress in preeclamptic women and the mechanism of albumin for stress reduction

AIMS

The present study to address one of the mechanisms in preeclampsia, examined whether levels of oxidative stress, human serum albumin, and endothelial function correlate in pregnant women and whether human serum albumin reduces levels of superoxide produced by NADPH oxidase activation in the human vascular smooth muscle cells.

MATERIALS AND METHODS

Pregnant women with (Preeclampsia group, n = 33) and without preeclampsia (Normal group, n = 37) were recruited to determine levels of reactive oxygen species (serum diacron-reactive oxygen metabolite [d-ROM]), and the flow-mediated dilation (FMD). Human coronary arterial smooth muscle cells or omental arteries were subjected to evaluate isometric force recordings, levels of superoxide, western immunoblotting, and immunohistochemistry. The superoxide scavenging assay was also performed in a cell-free system.

KEY FINDINGS

Women in the preeclampsia group demonstrated lower FMD and higher serum d-ROM values than those in the normal group. There were the inverse correlations between serum levels of d-ROM and the degree of FMD and between serum levels of albumin and those of d-ROM. D-glucose reduced the levcromakalim-induced dilation of human omental arteries, and it increased levels of superoxide and the recruitment of the NADPH oxidase subunit p47phox in human coronary arterial smooth muscle cells. Human serum albumin (0.05 to 0.5 g/dL) prevented these alterations whereas it exerted no superoxide scavenging effect.

SIGNIFICANCE

Serum albumin relates to oxidative stress inversely, but to the endothelial function positively, in pregnant women. Human serum albumin appears to reduce oxidative stress via NADPH oxidase inhibition in the human vascular smooth muscle, indicating that the serum level may be a critical determinant of vascular oxidative stress in some human diseases.

Extracellular Cyclophilin A, Especially Acetylated, Causes Pulmonary Hypertension by Stimulating Endothelial Apoptosis, Redox Stress, and Inflammation

OBJECTIVE

Oxidative stress and inflammation play key roles in the development of pulmonary arterial hypertension (PAH). Cyclophilin A (CypA) is secreted in response to oxidative stress and promotes inflammation and cardiovascular disease. Endothelial cell (EC) dysfunction is an early event in the pathogenesis of PAH. We evaluated the role of extracellular CypA in PAH and compared the effects of acetylated CypA (AcK-CypA, increased by oxidative stress) and CypA on EC dysfunction.

APPROACH AND RESULTS

In transgenic mice that express high levels of CypA in EC specifically, a PAH phenotype was observed at 3 months including increased right ventricular systolic pressure, α-smooth muscle actin expression in small arterioles, and CD45-positive cells in the lungs. Mechanistic analysis using cultured mouse pulmonary microvascular EC and human pulmonary microvascular EC showed that extracellular CypA and AcK-CypA stimulated EC inflammatory signals: increased VCAM1 (vascular cell adhesion molecule 1) and ICAM1 (intercellular adhesion molecule 1), phosphorylation of p65, and degradation of IkB. Extracellular CypA and AcK-CypA increased EC apoptosis measured by TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) staining, Apo-ONE assay, and caspase 3 cleavage. Oxidative stress stimulated CypA and AcK-CypA secretion, which further promoted EC oxidative stress. AcK-CypA, compared with CypA, stimulated greater increases in apoptosis, inflammation, and oxidative stress. MM284, a specific inhibitor of extracellular CypA, attenuated EC apoptosis induced by CypA and AcK-CypA.

CONCLUSIONS

EC-derived CypA (especially AcK-CypA) causes PAH by a presumptive mechanism involving increased EC apoptosis, inflammation, and oxidative stress. Our results suggest that inhibiting secreted extracellular CypA is a novel therapeutic approach for PAH.

Redox Proteomics and Platelet Activation: Understanding the Redox Proteome to Improve Platelet Quality for Transfusion

Blood banks use pathogen inactivation (PI) technologies to increase the safety of platelet concentrates (PCs). The characteristics of PI-treated PCs slightly differ from those of untreated PCs, but the underlying reasons are not well understood. One possible cause is the generation of oxidative stress during the PI process. This is of great interest since reactive oxygen species (ROS) act as second messengers in platelet functions. Furthermore, there are links between protein oxidation and phosphorylation, another mechanism that is critical for cell regulation. Current research efforts focus on understanding the underlying mechanisms and identifying new target proteins. Proteomics technologies represent powerful tools for investigating signaling pathways involving ROS and post-translational modifications such as phosphorylation, while quantitative techniques enable the comparison of the platelet resting state versus the stimulated state. In particular, redox cysteine is a key player in platelet activation upon stimulation by different agonists. This review highlights the experiments that have provided insights into the roles of ROS in platelet function and the implications for platelet transfusion, and potentially in diseases such as inflammation and platelet hyperactivity. The review also describes the implication of redox mechanism in platelet storage considerations.

TRPM8 downregulation by angiotensin II in vascular smooth muscle cells is involved in hypertension

Angiotensin II (Ang II)-induced injury of vascular smooth muscle cells (VSMCs) serves an important role in hypertension and other cardiovascular disorders. Transient receptor potential melastatin 8 (TRPM8) is a thermally‑regulated Ca2+‑permeable channel that is activated by reduced body temperature. Although several recent studies have revealed the regulatory effect of TRPM8 in vascular tone and hypertension, the precise role of TRPM8 in dysfunction of vascular smooth muscle cells (VSMCs) induced by Ang II remains elusive. In the present study, the possible function of TRPM8 in Ang II‑induced VSMCs malfunction in vivo and in vitro was investigated. In the aortae from rats that had undergone a two‑kidney one‑clip operation, which is a widely‑used renovascular hypertension model, the mRNA and protein levels of TRPM8 were reduced. In addition, exogenous Ang II treatment decreased TRPM8 mRNA and protein expression levels in primary cultures of rat VSMCs. TRPM8 activation by menthol, a pharmacological agonist, in VSMCs, significantly attenuated the Ang II‑induced increase in reactive oxygen species and H2O2 production. In addition, TRPM8 activation reduced the Ang II‑induced upregulation of NADPH oxidase (NOX) 1 and NOX4 in VSMCs. Furthermore, TRPM8 activation relieved the Ang II‑induced activation of ras homolog gene family, member A‑rho associated protein kinase 2 and janus kinase 2 signaling pathways in VSMCs. In conclusion, the results presented in the current study indicated that TRPM8 downregulation by Ang II in VSMCs may be involved in hypertension.

Daily sesame oil supplementation mitigates ketoconazole-induced oxidative stress-mediated apoptosis and hepatic injury

Ketoconazole (KCZ) is the most commonly used systemic antifungal drug. However, long-term treatment of KCZ induces hepatic injury. Oxidative stress is involved in KCZ-induced hepatic injury. Oxidative stress plays an important role in apoptosis-associated hepatic damage. Sesame oil is rich in potent antioxidants and antifungal constituents. It attenuates hepatic injury by inhibiting oxidative stress. Thus, sesame oil may protect against KCZ-induced oxidative stress, apoptosis and hepatic damage. The aim of the present study was to investigate the protective effect of sesame oil as a nutritional supplement on KCZ-induced hepatic injury in mice. KCZ (300 mg/kg/day) was administered by gastric intubation; 30 min later, sesame oil (0, 0.0625, 0.125, 0.25 or 0.5 ml/kg/day; p.o.) was administered to mice for 14 days. Blood and liver tissue were collected. Hepatic injury was evaluated by serum biochemistry and histology. Oxidative stress was evaluated by myeloperoxidase activity, p47-phox, reactive oxygen species generation, lipid peroxidation and glutathione level. Apoptosis was evaluated by p53, caspase-3, Bcl-2, Bax and Cyto-C expression. Osteopontin was measured to assess liver healing. Sesame oil attenuated hepatic injury; it also decreased oxidative stress and apoptosis in KCZ-treated mice. Sesame oil may be used as a nutritional supplement with existing antifungal therapies to neutralize the adverse hepatotoxic nature of antifungal drugs by attenuating hepatic apoptosis through redox system to protect and heal liver injury in KCZ-treated mice.

RhoA/Rho-Kinase in the Cardiovascular System

Twenty years ago, Rho-kinase was identified as an important downstream effector of the small GTP-binding protein, RhoA. Thereafter, a series of studies demonstrated the important roles of Rho-kinase in the cardiovascular system. The RhoA/Rho-kinase pathway is now widely known to play important roles in many cellular functions, including contraction, motility, proliferation, and apoptosis, and its excessive activity induces oxidative stress and promotes the development of cardiovascular diseases. Furthermore, the important role of Rho-kinase has been demonstrated in the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, and heart failure. Cyclophilin A is secreted by vascular smooth muscle cells and inflammatory cells and activated platelets in a Rho-kinase-dependent manner, playing important roles in a wide range of cardiovascular diseases. Thus, the RhoA/Rho-kinase pathway plays crucial roles under both physiological and pathological conditions and is an important therapeutic target in cardiovascular medicine. Recently, functional differences between ROCK1 and ROCK2 have been reported in vitro. ROCK1 is specifically cleaved by caspase-3, whereas granzyme B cleaves ROCK2. However, limited information is available on the functional differences and interactions between ROCK1 and ROCK2 in the cardiovascular system in vivo. Herein, we will review the recent advances about the importance of RhoA/Rho-kinase in the cardiovascular system.

Light and Dark of Reactive Oxygen Species for Vascular Function: 2014 ASVB (Asian Society of Vascular Biology)

Vascular-derived hydrogen peroxide (H2O2) serves as an important signaling molecule in the cardiovascular system and contributes to vascular homeostasis. H2O2 is a second messenger, transducing the oxidative signal into biological responses through posttranslational protein modification. The balance between oxidant and antioxidant systems regulates intracellular redox status, and their imbalance causes oxidative or reductive stress, leading to cellular damage in cardiovascular systems. Excessive H2O2 deteriorates vascular functions and promotes vascular disease through multiple pathways. The RhoA/Rho-kinase pathway plays an important role in various fundamental cellular functions, including production of excessive reactive oxygen species, leading to the development of cardiovascular diseases. Rho-kinase (ROCK1 and ROCK2) belongs to the family of serine/threonine kinases and is an important downstream effector of the small GTP-binding protein RhoA. Rho-kinase plays a crucial role in the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, stroke, and heart failure. Thus, Rho-kinase inhibitors may be useful for the treatment of cardiovascular diseases in humans. In this review, we will briefly discuss the roles of vascular-derived H2O2 and review the recent progress in the translational research on the therapeutic importance of the Rho-kinase pathway in cardiovascular medicine.

Cyclophilin A in cardiovascular homeostasis and diseases

Vascular homeostasis is regulated by complex interactions between many vascular cell components, including endothelial cells, vascular smooth muscle cells (VSMCs), adventitial inflammatory cells, and autonomic nervous system. The balance between oxidant and antioxidant systems determines intracellular redox status, and their imbalance can cause oxidative stress. Excessive oxidative stress is one of the important stimuli that induce cellular damage and dysregulation of vascular cell components, leading to vascular diseases through multiple pathways. Cyclophilin A (CyPA) is one of the causative proteins that mediate oxidative stress-induced cardiovascular dysfunction. CyPA was initially discovered as the intracellular receptor of the immunosuppressive drug cyclosporine 30 years ago. However, recent studies have established that CyPA is secreted from vascular cell components, such as endothelial cells and VSMCs. Extracellular CyPA augments the development of cardiovascular diseases. CyPA secretion is regulated by Rho-kinase, which contributes to the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, and heart failure. We recently reported that plasma CyPA levels are significantly higher in patients with coronary artery disease, which is associated with increased numbers of stenotic coronary arteries and the need for coronary intervention in such patients. Furthermore, we showed that the vascular erythropoietin (Epo)/Epo receptor system plays an important role in production of nitric oxide and maintenance of vascular redox state and homeostasis, with a potential mechanistic link to the Rho-kinase-CyPA pathway. In this article, I review the data on the protective role of the vascular Epo/Epo receptor system and discuss the roles of the CyPA/Rho-kinase system in cardiovascular diseases.

Expression and significance of cortactin and HDAC6 in human prostatic foamy gland carcinoma

Cortactin, the cytoplasmic substrate of HDAC6, is known to play an actin cytoskeletal regulatory role which is implicated in the motility of cancer cells, and thus in cancer progression. Its activity is found to be regulated by HDAC6. However, the significance of cortactin and HDAC6 remains unclear in uncommon histologic variant human prostatic foamy gland carcinoma (PfCa). In this study, we aimed to identify the expression and potential role of cortactin and HDAC6 in PfCa. Therefore, 16 PfCa specimens containing 48 foci with distinctive lesions were collected to identify the status of cortactin and HDAC6 by immunohistochemistry. Their correlation between clinicopathological characteristics and prognostic values were further analysed. The effect of cortactin and HDAC6 on prostate cancer cell migration and invasion was then evaluated in IA8 cells. The results showed that expression of cortactin and HDAC6 was significantly higher in PfCa foci, compared to that of high-grade prostatic intraepithelial neoplasia (HGPIN) foci and benign foci (P < 0.05). Cortactin and HDAC6 were associated with poor prognosis of patients with PfCa (P < 0.05). Multivariable Cox regression analysis showed HDAC6 level was a significant prognostic factor for survival of patients with PfCa (β = 1.200, Wald value = 7.282, P = 0.007, 95% CI = 1.389-7.941, P < 0.01, β > 0). Both knocking down cortactin and inhibition of HDAC6 activity with tubacin reduced in vitro migration and invasion ability of IA8 cells substantially. Furthermore, HDAC6 has prognostic value for patients with PfCa. Dysregulation of cortactin and HDAC6 is implicated in the invasiveness and migration of prostate cancer cells.

Nox family NADPH oxidases: Molecular mechanisms of activation

NADPH oxidases of the Nox family are important enzymatic sources of reactive oxygen species (ROS). Numerous homologue-specific mechanisms control the activity of this enzyme family involving calcium, free fatty acids, protein-protein interactions, intracellular trafficking, and posttranslational modifications such as phosphorylation, acetylation, or sumoylation. After a brief review on the classic pathways of Nox activation, this article will focus on novel mechanisms of homologue-specific activity control and on cell-specific aspects which govern Nox activity. From these findings of the recent years it must be concluded that the activity control of Nox enzymes is much more complex than anticipated. Moreover, depending on the cellular activity state, Nox enzymes are selectively activated or inactivated. The complex upstream signaling aspects of these events make the development of "intelligent" Nox inhibitors plausible, which selectively attenuate disease-related Nox-mediated ROS formation without altering physiological signaling ROS. This approach might be of relevance for Nox-mediated tissue injury in ischemia-reperfusion and inflammation and also for chronic Nox overactivation as present in cancer initiation and cardiovascular disease.

CD137-CD137L interaction regulates atherosclerosis via cyclophilin A in apolipoprotein E-deficient mice

Background

Our previous studies showed that increased levels of cyclophilin A (CyPA) may be a valuable marker for predicting the severity of acute coronary syndromes and that interruption of CD137-CD137L interactions diminished the formation and progression of atherosclerosis in apolipoprotein E-deficient (ApoE−/−) mice. Here, we sought to determine whether the proinflammatory factor CyPA is involved in atherosclerosis regulated by CD137-CD137L interactions.

Methods and Results

A constrictive collar was placed around the right carotid arteries of ApoE−/− mice that were fed a high-fat diet to induce atherosclerotic plaque formation. After that, the mice were intraperitoneally injected with anti-CD137 or anti-CD137L in the presence or absence of the recombinant lentiviral vectors LVTHM-CyPA or pGC-FU-CyPA, respectively. Interestingly, activation of CD137-CD137L was negatively correlated with CyPA expression in vivo and in vitro. Stimulating CD137-CD137L interaction significantly increased CyPA, which was concurrent with the upregulation of proinflammatory cytokines, chemokines and matrix metalloproteinases and resulted in the promotion of atherosclerosis in ApoE-/- mice. Silencing CyPA could eliminate these effects, and restoration of CyPA effectively and consistently attenuated the atherosclerotic suppression phenotypes elicited by the blockade of CD137-CD137L.

Conclusion

These observations suggest that CD137-CD137L interactions mediated via regulation of CyPA contribute to the progression of atherosclerosis.

Cyclophilin A is an important mediator of platelet function by regulating integrin αIIbβ3 bidirectional signalling

Cyclophilin A (CyPA) is an important mediator in cardiovascular diseases. It possesses peptidyl-prolyl cis-trans isomerase activity (PPIase) and chaperone functions, which regulate protein folding, intracellular trafficking and reactive oxygen species (ROS) production. Platelet glycoprotein receptor αIIbβ3 integrin activation is the common pathway for platelet activation. It was our objective to understand the mechanism by which CyPA-regulates αIIbβ3 activation in platelets. Mice deficient for CyPA (CyPA-/-) had prolonged tail bleeding time compared to wild-type (WT) controls despite equivalent platelet numbers. In vitro studies revealed that CyPA-/- platelets exhibited dramatically decreased thrombin-induced platelet aggregation. In vivo, formation of occlusive thrombi following FeCl3 injury was also significantly impaired in CyPA-/- mice compared with WT-controls. Furthermore, CyPA deficiency inhibited flow-induced thrombus formation in vitro. Flow cytometry demonstrated that thrombin-induced ROS production and αIIbβ3 activation were reduced in CyPA-/- platelets. Coimmunoprecipitation studies showed ROS-dependent increased association of CyPA and αIIbβ3. This association was dependent upon the PPIase activity of CyPA. Significantly, fibrinogen-platelet binding, platelet spreading and cytoskeleton reorganisation were also altered in CyPA-/- platelets. Moreover, CyPA deficiency prevented thrombin-induced αIIbβ3 and cytoskeleton association. In conclusion, CyPA is an important mediator in platelet function by regulation of αIIbβ3 bidirectionalsignalling through increased ROS production and facilitating interaction between αIIbβ3 and the cell cytoskeleton.

Dual roles of vascular-derived reactive oxygen species--with a special reference to hydrogen peroxide and cyclophilin A

Reactive oxygen species (ROS) have been considered to play a major role in the pathogenesis of cardiovascular diseases. However, this notion needs to be revised since recent evidence indicates that vascular-derived hydrogen peroxide (H2O2) serves as an important signaling molecule in the cardiovascular system at its low physiological concentrations. At low concentrations, H2O2 can act as a second messenger, transducing the oxidative signal into biological responses through post-translational protein modification. These structural changes ultimately lead to altered cellular function. Intracellular redox status is closely regulated by the balance between oxidant and antioxidant systems and their imbalance can cause oxidative or reductive stress, leading to cellular damage and dysregulation. For example, excessive H2O2 deteriorates vascular functions and promotes vascular disease through multiple pathways. Furthermore, cyclophilin A (CyPA) has been shown to be secreted from vascular smooth muscle cells and to augment the destructive effects of ROS, linking it to the development of many cardiovascular diseases. Thus, it is important to understand the H2O2 signaling and the roles of downstream effectors such as CyPA in the vascular system in order to develop new therapeutic strategies for cardiovascular diseases. In this review, we will discuss the dual roles of vascular-derived H2O2 in mediating vascular functions (physiological roles) and promoting vascular diseases (pathological roles), with particular emphasis on the function of CyPA. This article is part of a Special Issue entitled "Redox Signalling in the Cardiovascular System".