Dysfunctional and Dysregulated Nitric Oxide Synthases in Cardiovascular Disease: Mechanisms and Therapeutic Potential.

Nitric oxide (NO) plays an important and diverse signalling role in the cardiovascular system, contributing to the regulation of vascular tone, endothelial function, myocardial function, haemostasis, and thrombosis, amongst many other roles. NO is synthesised through the nitric oxide synthase (NOS)-dependent L-arginine-NO pathway, as well as the nitrate-nitrite-NO pathway. The three isoforms of NOS, namely neuronal (NOS1), inducible (NOS2), and endothelial (NOS3), have different localisation and functions in the human body, and are consequently thought to have differing pathophysiological roles. Furthermore, as we continue to develop a deepened understanding of the different roles of NOS isoforms in disease, the possibility of therapeutically modulating NOS activity has emerged. Indeed, impaired (or dysfunctional), as well as overactive (or dysregulated) NOS activity are attractive therapeutic targets in cardiovascular disease. This review aims to describe recent advances in elucidating the physiological role of NOS isoforms within the cardiovascular system, as well as mechanisms of dysfunctional and dysregulated NOS in cardiovascular disease. We then discuss the modulation of NO and NOS activity as a target in the development of novel cardiovascular therapeutics.

Detection of Elevated Level of Tetrahydrobiopterin in Serum Samples of ME/CFS Patients with Orthostatic Intolerance: A Pilot Study.

Myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) is a multisystem chronic illness characterized by severe muscle fatigue, pain, dizziness, and brain fog. Many patients with ME/CFS experience orthostatic intolerance (OI), which is characterized by frequent dizziness, light-headedness, and feeling faint while maintaining an upright posture. Despite intense investigation, the molecular mechanism of this debilitating condition is still unknown. OI is often manifested by cardiovascular alterations, such as reduced cerebral blood flow, reduced blood pressure, and diminished heart rate. The bioavailability of tetrahydrobiopterin (BH4), an essential cofactor of endothelial nitric oxide synthase (eNOS) enzyme, is tightly coupled with cardiovascular health and circulation. To explore the role of BH4 in ME/CFS, serum samples of CFS patients (n = 32), CFS patients with OI only (n = 10; CFS + OI), and CFS patients with both OI and small fiber polyneuropathy (n = 12; CFS + OI + SFN) were subjected to BH4 ELISA. Interestingly, our results revealed that the BH4 expression is significantly high in CFS, CFS + OI, and CFS + OI + SFN patients compared to age-/gender-matched controls. Finally, a ROS production assay in cultured microglial cells followed by Pearson correlation statistics indicated that the elevated BH4 in serum samples of CFS + OI patients might be associated with the oxidative stress response. These findings suggest that the regulation of BH4 metabolism could be a promising target for understanding the molecular mechanism of CFS and CFS with OI.

Quantitative proteomics reveals decreased expression of major urinary proteins in the liver of apoE/eNOS-DKO mice.

Endothelial nitric oxide synthase (eNOS)-derived nitric oxide (NO) plays an important role, not only in endothelium-dependent vasodilation but also in lipid and glucose homeostasis in the liver and exerts beneficial effects on mitochondrial biogenesis and respiration. Thus, the aim of our study was to use iTRAQ-based quantitative proteomics to investigate the changes in protein expression in the mitochondrial and cytosolic fractions isolated from the liver of the double (apolipoprotein E (apoE) and eNOS) knockout (apoE/eNOS-DKO) mice as compared to apoE KO mice (apoE-/- ) - an animal model of atherosclerosis and hepatic steatosis. Collectively, the deficiency of eNOS resulted in increased expression of proteins related to gluconeogenesis, fatty acids and cholesterol biosynthesis as well as the decreased expression of proteins participated in triglyceride breakdown, cholesterol transport, protein transcription & translation and processing in endoplasmic reticulum (ER). Moreover, one of the most downregulated proteins were major urinary proteins (MUPs), which are abundantly expressed in the liver and were shown to be involved in the regulation of lipid and glucose metabolism. The exact functional consequences of the revealed alterations require further investigation.

Protective Effects of Rhodiola Crenulata Extract on Hypoxia-Induced Endothelial Damage via Regulation of AMPK and ERK Pathways.

Rhodiola crenulata root extract (RCE) has been shown to possess protective activities against hypoxia both in vitro and in vivo. However, the effects of RCE on response to hypoxia in the endothelium remain unclear. In this study, we aimed to examine the effects of RCE in endothelial cells challenged with hypoxic exposure and to elucidate the underlying mechanisms. Human umbilical vein endothelial cells were pretreated with or without RCE and then exposed to hypoxia (1% O2) for 24 h. Cell viability, nitric oxide (NO) production, oxidative stress markers, as well as mechanistic readouts were studied. We found that hypoxia-induced cell death, impaired NO production, and oxidative stress. These responses were significantly attenuated by RCE treatment and were associated with the activation of AMP-activated kinase and extracellular signal-regulated kinase 1/2 signaling pathways. In summary, we showed that RCE protected endothelial cells from hypoxic insult and suggested that R. crenulata might be useful for the prevention of hypoxia-associated vascular dysfunction.

Role of glypican-1 in endothelial NOS activation under various steady shear stress magnitudes.

Blood flow patterns in proatherogenic and antiatherogenic regions are rather different. We hypothesize that the laminar flow with steady shear stress increased nitric oxide (NO) bioavailability while disturbed flow with low shear stress reduced it, which is mediating by glypican-1. Thus, we detected the expression of glypican-1 under different shear stress magnitudes, and tested whether the magnitude of shear stress determines the level of endothelial NO synthase (eNOS) via glypican-1 by using phosphatidylinositol phospholipase C (PI-PLC). Results revealed that the expression of glypican-1 depends on the magnitude and duration of shear stress loading. Activation of eNOS in HUVECs is downregulated by 4dyn/cm2 of shear stress, but is upregulated by 15dyn/cm2. Removal of glypican-1 significantly suppressed the 15dyn/cm2 shear stress-induced eNOS activity, and further reduced the 4dyn/cm2-inhibited eNOS activity. Therefore, eNOS activation depends on shear stress magnitudes and is mediated by glypican-1. The role of glypican-1 in mediating the eNOS activation under shear stress might involve in protecting the endothelial function against disturbed flow and enhancing the sensitive of the endothelial cell to laminar flow, supporting a potential role of glypican-1 against atherosclerosis.

Decoding cell death signals in liver inflammation.

Inflammation can be either beneficial or detrimental to the liver, depending on multiple factors. Mild (i.e., limited in intensity and destined to resolve) inflammatory responses have indeed been shown to exert consistent hepatoprotective effects, contributing to tissue repair and promoting the re-establishment of homeostasis. Conversely, excessive (i.e., disproportionate in intensity and permanent) inflammation may induce a massive loss of hepatocytes and hence exacerbate the severity of various hepatic conditions, including ischemia-reperfusion injury, systemic metabolic alterations (e.g., obesity, diabetes, non-alcoholic fatty liver disorders), alcoholic hepatitis, intoxication by xenobiotics and infection, de facto being associated with irreversible liver damage, fibrosis, and carcinogenesis. Both liver-resident cells (e.g., Kupffer cells, hepatic stellate cells, sinusoidal endothelial cells) and cells that are recruited in response to injury (e.g., monocytes, macrophages, dendritic cells, natural killer cells) emit pro-inflammatory signals including - but not limited to - cytokines, chemokines, lipid messengers, and reactive oxygen species that contribute to the apoptotic or necrotic demise of hepatocytes. In turn, dying hepatocytes release damage-associated molecular patterns that-upon binding to evolutionary conserved pattern recognition receptors-activate cells of the innate immune system to further stimulate inflammatory responses, hence establishing a highly hepatotoxic feedforward cycle of inflammation and cell death. In this review, we discuss the cellular and molecular mechanisms that account for the most deleterious effect of hepatic inflammation at the cellular level, that is, the initiation of a massive cell death response among hepatocytes.

saRNA guided iNOS up-regulation improves erectile function of diabetic rats.

PURPOSE: Promoter targeted saRNAs mediate sequence specific up-regulation of gene expression. We explored the therapeutic effect of RNA activation mediated iNOS gene activation on improving erectile function in a rat model of diabetes mellitus. MATERIALS AND METHODS: An optimal saRNA sequence specific for iNOS promoter was cloned into an adenoviral vector, resulting in AdU6/shiNOS and AdU6/shControl. The corresponding viruses were used to transduce cultured rat cavernous smooth muscle cells. Streptozotocin induced diabetes models were established in rats and used to test the effects of intracavernous delivery of iNOS saRNA viruses on erectile function. iNOS expression in the cavernous smooth muscle cells or penile tissue of treated rats was assessed by reverse transcriptase-polymerase chain reaction and Western blot. Cyclic guanosine monophosphate was analyzed by enzyme-linked immunosorbent assay. Intracavernous pressure in response to cavernous nerve stimulation was measured using a data acquisition system on post-injection days 1, 3, 5, 7, 10 and 14. RESULTS: Adenovirus mediated expression of iNOS saRNA caused sustained up-regulation of iNOS in cavernous smooth muscle cells. Intracavernous injection of AdU6/shiNOS activated iNOS expression in vivo and significantly increased peak intracavernous pressure in streptozotocin induced diabetic rats via nitric oxide/intracellular cyclic guanosine monophosphate activation. CONCLUSIONS: Results show that saRNA mediated iNOS over expression in the penis can restore erectile function in streptozocin diabetic rats via the nitric oxide-cyclic guanosine monophosphate pathway.

Formation, signaling functions, and metabolisms of nitrated cyclic nucleotide.

8-Nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP) is a unique derivative of guanosine 3',5'-cyclic monophosphate (cGMP) formed in mammalian and plant cells in response to production of nitric oxide and reactive oxygen species. 8-Nitro-cGMP possesses signaling activity inherited from parental cGMP, including induction of vasorelaxation through activation of cGMP-dependent protein kinase. On the other hand, 8-nitro-cGMP mediates cellular signaling that is not observed for native cGMP, e.g., it behaves as an electrophile and reacts with protein sulfhydryls, which results in cGMP adduction to protein sulfhydryls (protein S-guanylation). Several proteins have been identified as targets for endogenous protein S-guanylation, including Kelch-like ECH-associated protein 1 (Keap1), H-Ras, and mitochondrial heat shock proteins. 8-Nitro-cGMP signaling via protein S-guanylation of those proteins may have evolved to convey adaptive cellular stress responses. 8-Nitro-cGMP may not undergo conventional cGMP metabolism because of its resistance to phosphodiesterases. Hydrogen sulfide has recently been identified as a potent regulator for metabolisms of electrophiles including 8-nitro-cGMP, through sulfhydration of electrophiles, e.g., leading to the formation of 8-SH-cGMP. Better understanding of the molecular basis for the formation, signaling functions, and metabolisms of 8-nitro-cGMP would be useful for the development of new diagnostic approaches and treatment of diseases related to oxidative stress and redox metabolisms.

Insights into human eNOS, nNOS and iNOS structures and medicinal indications from statistical analyses of their interactions with bound compounds.

83 Structures of human nNOS, 55 structures of human eNOS, 13 structures of iNOS, and about 126 reported NOS-bound compounds are summarized and analyzed. Structural and statistical analysis show that, at least one copy of each analyzed compound binds to the active site (the substrate arginine binding site) of human NOS. And binding features of the three isoforms show differences, but the binding preference of compounds is not in the way helpful for inhibitor design targeting nNOS and iNOS, or for activator design targeting eNOS. This research shows that there is a strong structural and functional similarity between oxygenase domains of human NOS isoforms, especially the architecture, residue composition, size, shape, and distribution profile of hydrophobicity, polarity and charge of the active site. The selectivity and efficacy of inhibitors over the rest of isoforms rely a lot on chance and randomness. Further increase of selectivity via rational improvement is uncertain, unpredictable and unreliable, therefore, to achieve high selectivity through targeting this site is complicated and requires combinative investigation. After analysis on the current two targeting sites in NOS, the highly conserved arginine binding pocket and H4B binding pocket, new potential drug-targeting sites are proposed based on structure and sequence profiling. This comprehensive analysis on the structure and interaction profiles of human NOS and bound compounds provides fresh insights for drug discovery and pharmacological research, and the new discovery here is practically applied to guide protein-structure based drug discovery.

Blood flow patterns switch VEGFR2 activity through differential S-nitrosylation and S-oxidation.

Vascular endothelial growth factor receptor-2 (VEGFR2) plays a key role in maintaining vascular endothelial homeostasis. Here, we show that blood flows determine activation and inactivation of VEGFR2 through selective cysteine modifications. VEGFR2 activation is regulated by reversible oxidation at Cys1206 residue. H2O2-mediated VEGFR2 oxidation is induced by oscillatory flow in vascular endothelial cells through the induction of NADPH oxidase-4 expression. In contrast, laminar flow induces the expression of endothelial nitric oxide synthase and results in the S-nitrosylation of VEGFR2 at Cys1206, which counteracts the oxidative inactivation. The shear stress model study reveals that disturbed blood flow operated by partial ligation in the carotid arteries induces endothelial damage and intimal hyperplasia in control mice but not in knock-in mice harboring the oxidation-resistant mutant (C1206S) of VEGFR2. Thus, our findings reveal that flow-dependent redox regulation of the VEGFR2 kinase is critical for the structural and functional integrity of the arterial endothelium.

Structure, Distribution, Regulation, and Function of Splice Variant Isoforms of Nitric Oxide Synthase Family in the Nervous System.

Nitric oxide (NO) is a small molecule produced by nitric oxide synthase (NOS) with various physio-pathological functions in the body. There are three main NOS isoforms, including the endothelial (eNOS), inducible (iNOS), and neuronal NOS (nNOS), that exist in the peripheral organs and nervous systems of humans and rodents. Moreover, NOS includes other identified NOS isoforms, such as retinal Muller glial cells (mNOS), mitochondrial (mtNOS), penile (PnNOS), testis-specific (TnNOS), and invertebrate Drosophila NOS (dNOS), which are the lesser-known types. It is proposed that the versatile functions of NOS isoforms depend on various NOS splice variant subtypes and their expression in the neural (e.g., brain, and spinal cord) and non-neuronal tissues (e.g., lung, kidney, liver, and GI tract). Therefore, this review summarizes the NOS subtypes, splice variants, targeted splicing expression in the body, and their proposed physio-pathological functions. At last, alternative NOS subtypes and isoforms, which have previously received scant attention, will be addressed in this article.

Role of endothelial nitric oxide synthase for early brain injury after subarachnoid hemorrhage in mice.

The first few hours and days after subarachnoid hemorrhage (SAH) are characterized by cerebral ischemia, spasms of pial arterioles, and a significant reduction of cerebral microperfusion, however, the mechanisms of this early microcirculatory dysfunction are still unknown. Endothelial nitric oxide production is reduced after SAH and exogenous application of NO reduces post-hemorrhagic microvasospasm. Therefore, we hypothesize that the endothelial NO-synthase (eNOS) may be involved in the formation of microvasospasms, microcirculatory dysfunction, and unfavorable outcome after SAH. SAH was induced in male eNOS deficient (eNOS-/-) mice by endovascular MCA perforation. Three hours later, the cerebral microcirculation was visualized using in vivo 2-photon-microscopy. eNOS-/- mice had more severe SAHs, more severe ischemia, three time more rebleedings, and a massively increased mortality (50 vs. 0%) as compared to wild type (WT) littermate controls. Three hours after SAH eNOS-/- mice had fewer perfused microvessels and 40% more microvasospasms than WT mice. The current study indicates that a proper function of eNOS plays a key role for a favorable outcome after SAH and helps to explain why patients suffering from hypertension or other conditions associated with impaired eNOS function, have a higher risk of unfavorable outcome after SAH.

Acute effects of cigarette smoke on Endothelial Nitric Oxide synthase, vascular cell adhesion molecule 1 and aortic intima media thickness.

Background. Cigarette smoking could induce endothelial dysfunction and the increase of circulating markers of inflammation by activation of monocytes. This can lead to increased intima media thickness (IMT) of entire blood vessels and result in acceleration of the atherosclerosis process. However, to our knowledge, little is known about the role of cigarette smoking in this atherosclerotic inflammatory process. The aim of this study is to explore the link between cigarette smoking and its effect on endothelial nitric oxide synthase (e-NOS) and vascular cell adhesion molecule 1 (VCAM-1). Methods. An experimental study with a post-test only controlled group design was used. We used 18 Wistar rats ( Rattus norvegicus) randomly subdivided into two groups: group K (-) were not exposed to tobacco smoke, whereas group K (+) were exposed to smoke equivalent of more than 40 cigarettes for 28 days daily. After 28 days, samples were analyzed for e-NOS, VCAM-1 and aortic IMT. Results . Our results indicate that tobacco smoke can enhance the expression of VCAM-1 on rat cardiac vascular endothelial cells, resulting in a decreased expression of e-NOS level and increase of aortic IMT. Linear regression model found that eNOS level negatively correlated wiith aortic IMT ( r 2 = 0.584, ß = -0.764, p < 0.001), whereas VCAM-1 expression did not correlate with aortic IMT ( r 2 = 0.197, p = 0.065). Conclusion. Low e-NOS level and high VCAM-1 level observed after cigarette smoke exposure which may increase aortic IMT.

Gypenoside XVII protects against myocardial ischemia and reperfusion injury by inhibiting ER stress-induced mitochondrial injury.

BACKGROUND: Effective strategies are dramatically needed to prevent and improve the recovery from myocardial ischemia and reperfusion (I/R) injury. Direct interactions between the mitochondria and endoplasmic reticulum (ER) during heart diseases have been recently investigated. This study was designed to explore the cardioprotective effects of gypenoside XVII (GP-17) against I/R injury. The roles of ER stress, mitochondrial injury, and their crosstalk within I/R injury and in GP-17-induced cardioprotection are also explored. METHODS: Cardiac contractility function was recorded in Langendorff-perfused rat hearts. The effects of GP-17 on mitochondrial function including mitochondrial permeability transition pore opening, reactive oxygen species production, and respiratory function were determined using fluorescence detection kits on mitochondria isolated from the rat hearts. H9c2 cardiomyocytes were used to explore the effects of GP-17 on hypoxia/reoxygenation. RESULTS: We found that GP-17 inhibits myocardial apoptosis, reduces cardiac dysfunction, and improves contractile recovery in rat hearts. Our results also demonstrate that apoptosis induced by I/R is predominantly mediated by ER stress and associated with mitochondrial injury. Moreover, the cardioprotective effects of GP-17 are controlled by the PI3K/AKT and P38 signaling pathways. CONCLUSION: GP-17 inhibits I/R-induced mitochondrial injury by delaying the onset of ER stress through the PI3K/AKT and P38 signaling pathways.

Effects of onopordia, a novel isolated compound from Onopordon acanthium, on pentylenetetrazole-induced seizures in mice: Possible involvement of nitric oxide pathway.

Epilepsy is identified as a brain disorder and characterized by unpredictable disruption of normal brain function. Due to adverse side effect associated with antiepileptic drugs and also resistance profile, improvement of antiepileptic medications with more beneficial anticonvulsant activity is essential. Natural products have demonstrated their therapeutic properties such as anxiolytic, antidepressant and anticonvulsant activities and a source for identification of novel lead compounds. Therefore, the purpose of this study was to evaluate the effects of Onopordon acanthium secondary metabolite, onopordia, on pentylenetetrazole (PTZ)-induced seizure in male mice and investigate the possible role of nitric oxide pathway. Different doses of onopordia (0.1, 1 and 10 mg/kg) and phenobarbital (20 mg/kg) were administered intraperitoneally (i.p., 30, 60 and 120 min) prior to induction of epileptic seizure and compared to control groups. Onopordia demonstrated anticonvulsant effects when administrated at dose of 10 mg/kg, i.p. and optimum time 60 min prior to induction of seizure. Anticonvulsant effect of onopordia was blocked by applying a single dose of a non-selective nitric oxide synthase (NOS) inhibitor, Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME; 10 mg/kg, i.p.), and also a single dose of a selective neuronal NOS (nNOS) inhibitor, 7-nitroindazole (7-NI; 30 mg/kg, i.p.). Administration of ketamine as a N-Methyl-d-aspartic acid (NMDA) receptor antagonist (0.5 mg/kg; i.p.) with onopordia did not change the anticonvulsant effect of onopordia. The results of the present study demonstrated the anticonvulsant effect of onopordia as a new lead compound and also contribution of NO/nNOS pathway on PTZ-induced seizure in mice.

Impact of Endothelial NOS VNTR Variant on Susceptibility to Diabetic Neuropathy and Type 2 Diabetes Mellitus.

PURPOSE: The aim of this study was to evaluate whether the VNTR intron 4b/4a variant in the eNOS gene is associated with type 2 diabetes mellitus (T2DM) and DPN. METHODS: A total of 598 subjects were enrolled in the study. eNOS VNTR 4b/4a variant was genotyped by polymerase chain reaction (PCR) method. RESULTS: eNOS VNTR intron 4b/4b genotype and b allele increased in patients with both DPN and T2DM compared healthy controls (p=0.0005, OR:1.94, p= 0.000002, OR:4.10, respectively). 4a/4b genotype was more prevalent in controls than in DPN and T2DM patients (p=0.00008, OR:0.46; p=0.000004, OR:0.24, respectively). eNOS VNTR b allele was more common in DPN patients and T2DM patients compared with controls (p=0.007, p=0.00002, respectively). CONCLUSION: The eNOS VNTR "4b/4b" homozygous genotype and hence "4b"allele as a genetic risk factor for T2DM and DPN, which may serve as a useful marker of increased susceptibility to the risk of these disorders.

Changes in nitric oxide synthase levels are associated with impaired cardiac function and tolerance to ischemia-reperfusion injury in male rats with transient congenital hypothyroidism.

Transient congenital hypothyroidism (TCH) has long-lasting consequences on the cardiovascular system during adulthood. The aim of this study was to determine whether nitric oxide (NO) and NO-producing enzymes are involved in impaired cardiac function as well as decreased tolerance to ischemia-reperfusion (IR) injury in adult male rats with TCH. Pregnant rats were divided into control and hypothyroid groups. Male offspring rats were categorized in control and hypothyroid (TCH) groups at week 16. Levels of NOx (nitrate+nitrite) and neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS) were measured in hearts of rats and isolated perfused hearts from both groups were subjected to IR. Levels of NOx and NOSs were also measured in both groups after ischemia. Compared with controls, heart NOx levels were higher at baseline (48.0 ± 4.9 vs. 35.0 ± 2.6 µmol/L; P = 0.034) and following IR (103.6 ± 4.2 vs. 70.2 ± 2.7 µmol/L; P < 0.001) in rat with TCH. At baseline, compared with controls, heart iNOS and nNOS levels were significantly higher in rats with TCH (6.12 ± 0.34 vs. 4.78 ± 0.27 ng/mg protein; P = 0.008 for iNOS and 4.87 ± 0.28 vs. 3.55 ± 0.23 ng/mg protein; P = 0.003 for nNOS). Following IR, in rats with TCH, heart iNOS levels increased (11.75 ± 2.02 vs. 6.12 ± 0.34, ng/mg protein; P = 0.015) whereas nNOS level decreased (4.10 ± 0.25 vs. 4.87 ± 0.28 ng/mg protein; P = 0.063). Adverse effects of TCH on cardiac function are associated with increased ratio of iNOS/eNOS; in addition, increased heart nNOS levels are involved in impaired cardiac function while its decrease is associated with decreased tolerance to IR injury.

High risk of essential hypertension in males with intron 4 VNTR polymorphism of eNOS gene.

In this study 250 patients with essential hypertension were investigated in comparison to 218 normotensives for association with epidemiological parameters. Of these DNA samples from 176 patients and 168 controls were analyzed for intron 4 27bp repeat polymorphism of eNOS gene. The study revealed significantly high risk of essential hypertension for individuals who were obese, with a positive family history and with non-vegetarian food habits. Though the intron 4b/a polymorphism of eNOS gene did not reveal any association with essential hypertension in general, males with a/a genotype of the polymorphism did show significantly high risk for developing hypertension.

A Role of Agrin in Maintaining the Stability of Vascular Endothelial Growth Factor Receptor-2 during Tumor Angiogenesis.

Endothelial cell (EC) recruitment is central to the vascularization of tumors. Although several proteoglycans have been implicated in cancer and angiogenesis, their roles in EC recruitment and vascularization during tumorigenesis remain poorly understood. Here, we reveal that Agrin, which is secreted in liver cancer, promotes angiogenesis by recruiting ECs within tumors and metastatic lesions and facilitates adhesion of cancer cells to ECs. In ECs, Agrin-induced angiogenesis and adherence to cancer cells are mediated by Integrin-ß1, Lrp4-MuSK pathways involving focal adhesion kinase. Mechanistically, we uncover that Agrin regulates VEGFR2 levels that sustain the angiogenic property of ECs and adherence to cancer cells. Agrin attributes an ECM stiffness-based stabilization of VEGFR2 by enhancing interactions with Integrin-ß1-Lrp4 and additionally stimulates endothelial nitric-oxide synthase (e-NOS) signaling. Therefore, we propose that cross-talk between Agrin-expressing cancer and ECs favor angiogenesis by sustaining the VEGFR2 pathway.

Fasudil hydrochloride ameliorates memory deficits in rat model of streptozotocin-induced Alzheimer's disease: Involvement of PI3-kinase, eNOS and NFκB.

Restoration of PI3-kinase signaling portrays therapeutic potential in Alzheimer's disease (AD). Hyperactive Rho-kinase in AD negatively modulates PI3-kinase pathway, thereby cause cognitive decline. Fasudil is a Rho-kinase inhibitor that has shown therapeutic benefits in brain disorders. The present study is aimed to decipher the role of PI3-kinase pathway in neuroprotective activity of fasudil using STZ-ICV model of AD. MWM and NORT showed that fasudil (300 µg/kg, ICV) averted the STZ-ICV (3 mg/kg) induced memory dysfunctions in rats. Wortmannin (5 µg/rat) or l-NAME (20 mg/kg) attenuated the memory restorative function of fasudil in STZ treated rats. However, l-Arginine (50 mg/kg) group exhibited marked improvement in memory functions. Markers of oxidative stress (TBARS, GSH, SOD, CAT), nitrite, AChE, TNF-α, eNOS and NFκB were measured in whole brain of rats. STZ-ICV group exhibited significant elevation in brain oxidative stress, AChE activity, TNF-α, NFκB expression and decrease in eNOS level. These effects of STZ were effectively ameliorated by administration of fasudil for 21 days. Wortmannin (PI3-kinase inhibitor) or l-NAME (NOS blocker) attenuated the antioxidative, anti-inflammatory and cholinergic activities of fasudil. Although brain nitrite content was decreased by l-NAME and wortmannin, the l-NAME group depicted rise in eNOS content (not activity) and NFκB expression, whereas, decrease in same was observed in wortmannin group. l-Arginine lowered the brain oxidative stress, inflammation, AChE activity, eNOS expression (not activity), NFκB levels and elevated nitrite content. In STZ-ICV rat model of AD, fasudil (Rho-kinase inhibitor) ameliorated the AD symptoms by reinstating PI3-kinase mediated upregulation of eNOS and control over brain NFκB activity.