Cytochrome P450 (CYP) 2J2 gene transfection attenuates MMP-9 via inhibition of NF-kappabeta in hyperhomocysteinemia

Arachidonic acid metabolism in health and disease

Arachidonic acid (AA), an n-6 essential fatty acid, is a major component of mammalian cells and can be released by phospholipase A2. Accumulating evidence indicates that AA plays essential biochemical roles, as it is the direct precursor of bioactive lipid metabolites of eicosanoids such as prostaglandins, leukotrienes, and epoxyeicosatrienoic acid obtained from three distinct enzymatic metabolic pathways: the cyclooxygenase pathway, lipoxygenase pathway, and cytochrome P450 pathway. AA metabolism is involved not only in cell differentiation, tissue development, and organ function but also in the progression of diseases, such as hepatic fibrosis, neurodegeneration, obesity, diabetes, and cancers. These eicosanoids are generally considered proinflammatory molecules, as they can trigger oxidative stress and stimulate the immune response. Therefore, interventions in AA metabolic pathways are effective ways to manage inflammatory-related diseases in the clinic. Currently, inhibitors targeting enzymes related to AA metabolic pathways are an important area of drug discovery. Moreover, many advances have also been made in clinical studies of AA metabolic inhibitors in combination with chemotherapy and immunotherapy. Herein, we review the discovery of AA and focus on AA metabolism in relation to health and diseases. Furthermore, inhibitors targeting AA metabolism are summarized, and potential clinical applications are discussed.

Effect of inflammation on cytochrome P450-mediated arachidonic acid metabolism and the consequences on cardiac hypertrophy

The incidence of heart failure (HF) is generally preceded by cardiac hypertrophy (CH), which is the enlargement of cardiac myocytes in response to stress. During CH, the metabolism of arachidonic acid (AA), which is present in the cell membrane phospholipids, is modulated. Metabolism of AA gives rise to hydroxyeicosatetraenoic acids (HETEs) and epoxyeicosatrienoic acids (EETs) via cytochrome P450 (CYP) ω-hydroxylases and CYP epoxygenases, respectively. A plethora of studies demonstrated the involvement of CYP-mediated AA metabolites in the pathogenesis of CH. Also, inflammation is known to be a characteristic hallmark of CH. In this review, our aim is to highlight the impact of inflammation on CYP-derived AA metabolites and CH. Inflammation is shown to modulate the expression of various CYP ω-hydroxylases and CYP epoxygenases and their respective metabolites in the heart. In general, HETEs such as 20-HETE and mid-chain HETEs are pro-inflammatory, while EETs are characterized by their anti-inflammatory and cardioprotective properties. Several mechanisms are implicated in inflammation-induced CH, including the modulation of NF-κB and MAPK. This review demonstrated the inflammatory modulation of cardiac CYPs and their metabolites in the context of CH and the anti-inflammatory strategies that can be employed in the treatment of CH and HF.

CYP450 Epoxygenase Metabolites, Epoxyeicosatrienoic Acids, as Novel Anti-Inflammatory Mediators

Inflammation plays a crucial role in the initiation and development of a wide range of systemic illnesses. Epoxyeicosatrienoic acids (EETs) are derived from arachidonic acid (AA) metabolized by CYP450 epoxygenase (CYP450) and are subsequently hydrolyzed by soluble epoxide hydrolase (sEH) to dihydroxyeicosatrienoic acids (DHETs), which are merely biologically active. EETs possess a wide range of established protective effects on many systems of which anti-inflammatory actions have gained great interest. EETs attenuate vascular inflammation and remodeling by inhibiting activation of endothelial cells and reducing cross-talk between inflammatory cells and blood vessels. EETs also process direct and indirect anti-inflammatory properties in the myocardium and therefore alleviate inflammatory cardiomyopathy and cardiac remodeling. Moreover, emerging studies show the substantial roles of EETs in relieving inflammation under other pathophysiological environments, such as diabetes, sepsis, lung injuries, neurodegenerative disease, hepatic diseases, kidney injury, and arthritis. Furthermore, pharmacological manipulations of the AA-CYP450-EETs-sEH pathway have demonstrated a contribution to the alleviation of numerous inflammatory diseases, which highlight a therapeutic potential of drugs targeting this pathway. This review summarizes the progress of AA-CYP450-EETs-sEH pathway in regulation of inflammation under different pathological conditions and discusses the existing challenges and future direction of this research field.

Hyperhomocysteinemia dysregulates plasma levels of polyunsaturated fatty acids-derived eicosanoids

Hyperhomocysteinemia (HHcy) contributes to the incidence of many cardiovascular diseases (CVD). Our group have previously established crucial roles of eicosanoids and homocysteine in the incidence of vascular injury in diabetic retinopathy and renal injury. Using cystathionine-β-synthase heterozygous mice (cβs+/-) as a model of HHcy, the current study was designed to determine the impact of homocysteine on circulating levels of lipid mediators derived from polyunsaturated fatty acids (PUFA). Plasma samples were isolated from wild-type (WT) and cβs+/- mice for the assessment of eicosanoids levels using LC/MS. Plasma 12/15-lipoxygenase (12/15-LOX) activity significantly decreased in cβs+/- vs. WT control mice. LOX-derived metabolites from both omega-3 and omega-6 PUFA were also reduced in cβs+/- mice compared to WT control (P < 0.05). Contrary to LOX metabolites, cytochrome P450 (CYP) metabolites from omega-3 and omega-6 PUFA were significantly elevated in cβs+/- mice compared to WT control. Epoxyeicosatrienoic acids (EETs) are epoxides derived from arachidonic acid (AA) metabolism by CYP with anti-inflammatory properties and are known to limit vascular injury, however their physiological role is limited by their rapid degradation by soluble epoxide hydrolase (sEH) to their corresponding diols (DiHETrEs). In cβs+/- mice, a significant decrease in the plasma EETs bioavailability was obvious as evident by the decrease in EETs/ DiHETrEs ratio relative to WT control mice. Cyclooxygenase (COX) metabolites were also significantly decreased in cβs+/- vs. WT control mice. These data suggest that HHcy impacts eicosanoids metabolism through decreasing LOX and COX metabolic activities while increasing CYP metabolic activity. The increase in AA metabolism by CYP was also associated with increase in sEH activity and decrease in EETs bioavailability. Dysregulation of eicosanoids metabolism could be a contributing factor to the incidence and progression of HHcy-induced CVD.

Epoxyeicosatrienoic acids prevent cardiomyocytes against sepsis by A2AR-induced activation of PI3K and PPARγ

Although epoxyeicosatrienoic acids (EETs) have multiple protective effects against different diseases, whether they can improve the pathogenesis of lipopolysaccharide (LPS)-induced septic cardiac dysfunction remains unknown. We investigated the effects of EETs on the LPS-induced inflammatory response in myocardial dysfunction mice and H9c2 cardiac myocytes. Cardiac-specific CYP2J2 transgenic mice (Tr) showed improved cardiac function and reduced inflammation response after administration with LPS, while the protective effects were not observed in A_2A adenosine receptor (A_2AR/ADORA2A)-deficient mice (knockout/KO). In vitro, EETs prevented LPS-induced inflammation and apoptosis in the cardiomyocytes via A_2AR activation. Moreover, ZM241385 (A_2AR inhibitor) attenuated the cardioprotective properties of EETs. Further investigation demonstrated that A_2AR signal pathway activation partly regulated phosphatidylinositol 3-kinase (PI3K) and peroxisome proliferator-activated receptor-γ (PPARγ) expression. This is the first report on EETs exerting cardioprotective effects against LPS-induced cardiomyocyte injury via A_2AR activation.

Hydrogen sulfide attenuates hyperhomocysteinemia-induced blood-brain barrier permeability by inhibiting MMP-9

Backgroud: Hyperhomocysteinemia (HHcy) is implicated in various neurovascular disorders including vascular dementia, subarachnoid hemorrhage and stroke. Elevated homocysteine (Hcy) levels are associated with increased oxidative stress and compromised blood-brain barrier (BBB) integrity. Hydrogen sulfide (H₂S) has recently emerged as potent neuroprotective molecule in various neurological conditions including those associated with HHcy. The present study evaluates the protective effect of sodium hydrogen sulfide (NaHS; a source of H₂S) on HHcy-induced BBB dysfunction and underpin molecular mechanisms.Materials and methods: Supplementation of NaHS restored the increased BBB permeability in the cortex and hippocampus of HHcy animals assessed in terms of diffused sodium fluorescein and Evans blue tracer dyes in the brain. Activity of matrix metalloproteinases (MMPs) assessed by gelatinase activity and in situ gelatinase assay was restored to the normal in the cortex and hippocampus of HHcy animals supplemented with NaHS.Results: Application of gelatin zymography revealed that specifically MMP-9 activity was increased in the cortex and hippocampus of HHcy animals, which was inhibited by NaHS supplementation. Real-time RT-PCR analysis showed that NaHS administration also decreased mRNA expression of MMP-9 in the hippocampus of HHcy animals. NaHS supplementation was further observed to reduce water retention in the brain regions of Hcy treated animals.Conclusion: Taken together, these findings suggest that NaHS supplementation ameliorates HHcy-induced BBB permeability and brain edema by inhibiting the mRNA expression and activity of MMP-9. Therefore, H₂S and H₂S releasing drugs may be used as a novel therapeutic approach to treat HHcy-associated neurovascular disorders.

Mid-gestation serum lipidomic profile associations with spontaneous preterm birth are influenced by body mass index

Spontaneous preterm birth (sPTB) is a major cause of infant morbidity and mortality. While metabolic changes leading to preterm birth are unknown, several factors including dyslipidemia and inflammation have been implicated and paradoxically both low (<18.5 kg/m²) and high (>30 kg/m²) body mass indices (BMIs) are risk factors for this condition. The objective of the study was to identify BMI-associated metabolic perturbations and potential mid-gestation serum biomarkers of preterm birth in a cohort of underweight, normal weight and obese women experiencing either sPTB or full-term deliveries (n = 102; n = 17/group). For this purpose, we combined untargeted metabolomics and lipidomics with targeted metabolic profiling of major regulators of inflammation and metabolism, including oxylipins, endocannabinoids, bile acids and ceramides. Women who were obese and had sPTB showed elevated oxidative stress and dyslipidemia characterized by elevated serum free fatty acids. Women who were underweight-associated sPTB also showed evidence of dyslipidemia characterized by elevated phospholipids, unsaturated triglycerides, sphingomyelins, cholesteryl esters and long-chain acylcarnitines. In normal weight women experiencing sPTB, the relative abundance of 14(15)-epoxyeicosatrienoic acid and 14,15-dihydroxyeicosatrienoic acids to other regioisomers were altered at mid-pregnancy. This phenomenon is not yet associated with any biological process, but may be linked to estrogen metabolism. These changes were differentially modulated across BMI groups. In conclusion, using metabolomics we observed distinct BMI-dependent metabolic manifestations among women who had sPTB. These observations suggest the potential to predict sPTB mid-gestation using a new set of metabolomic markers and BMI stratification. This study opens the door to further investigate the role of cytochrome P450/epoxide hydrolase metabolism in sPTB.

The Anti-inflammatory Effect of Soluble Epoxide Hydrolase Inhibitor and 14, 15-EET in Kawasaki Disease Through PPARγ/STAT1 Signaling Pathway

Soluble epoxide hydrolase (sEH) is responsible for rapid degradation of 14, 15-EET, which is one of the isomers of EETs and plays an important role in cardiovascular diseases. In this study, we investigated the mechanism by which sEH inhibitor AUDA played an anti-inflammatory effect in HCAECs. Our results indicated that AUDA treatment promoted PPARγ expression, while knockdown of PPARγ blocked the cell growth and STAT1 expression inhibition induced by 100 μmol/L AUDA in HCAECs. AUDA also inhibited the overexpression of TNF-α, IL-1 β, and MMP-9 induced by KD sera in HCAECs. Moreover, 30 blood samples from children with Kawasaki disease (KD) were collected with 30 healthy children as the control group. QPCR and ELISA assays were used to detect the level of 14, 15-EET, TNF-α, IL-1β, and MMP-9. We found that the level of 14, 15-EET was higher in peripheral blood of children with KD compared with healthy controls (P < 0.05). In comparison to KD children with non-coronary artery lesion (nCAL), the level of 14, 15-EET was higher in peripheral blood of KD children with coronary artery lesion (CAL) (P < 0.05). Compared with healthy control group, the expression levels of TNF-α, IL-1β, and MMP-9 in patients with KD were significantly up-regulated. Compared with nCAL KD children, the expression levels of TNF-α, IL-1β, and MMP-9 in CAL children were abnormally high (P < 0.05). Our study indicated that AUDA played an anti-inflammatory effect in HCAECs through PPARγ/STAT1 signaling pathway, and 14, 15-EET is up-regulated in children with KD, suggesting that 14, 15-EET involved in the progression of KD.

Fatty acids modulate the expression of pyruvate kinase and arachidonate-lipoxygenase through PPARγ/CYP2C45 pathway: a link to goose fatty liver

Cytochrome P-450 2C45 (CYP2C45) is the most highly expressed cytochrome P-450 isoform in chicken liver, and may play an important role in avian liver biology. However, information regarding the function of CYP2C45 in fatty liver is generally limited. The aim of this study was to investigate the role of CYP2C45 during the development of goose fatty liver. Our result indicated that the transcription of CYP2C45, together with PK and ALOX5, was increased in goose liver upon overfeeding for 19 D (P < 0.05). In goose primary hepatocytes, CYP2C45 RNA expression was also upgraded by the treatment with various chemicals like insulin, the fatty acids, and PPAR agonists (P < 0.05). We also found that both CYP2C45 overexpression and troglitazone treatment could increase the expression of pyruvate kinase (PK) and arachidonate 5-lipoxygenase (ALOX5), and furthermore, showed that the up-regulation of PK and ALOX5 induced by troglitazone could be suppressed by small interfering RNAs targeting CYP2C45 (P < 0.05). These findings suggest that fatty acids treatment and the overfeeding can induce the up-regulation of CYP2C45 expression possibly via PPARγ and that the induction of PK and ALOX5 in goose fatty liver is at least partially attributed to fatty acid-induced expression of CYP2C45. Thus, our data provides an insight into the mechanism by which glycolysis and arachidonic acid metabolism are modulated in goose fatty liver.

Triumph and tumult of matrix metalloproteinases and their crosstalk with eicosanoids in cancer

Cancer development and metastasis are associated to perturbation in metabolic functions of tumor cells and surrounding inflammatory and stromal cell responses. Eicosanoids and lipid mediators, in this regard, attract potential attention during cancer development. Eicosanoids, which include prostaglandin, prostacyclin, thromboxane, and leukotriene, are synthesized from arachidonic acid when cells are stimulated by stress, cytokines, or other growth factors. However, the underlying mechanism of eicosanoids in cancer development, specially their interactions with proto-oncogene factors in tumor microenvironment, remain unexplored. On the other hand, matrix metalloproteinases (MMPs) are a group of zinc-dependent endopeptidases which are involved in degradation of different extracellular matrix (ECM) proteins. MMPs are associated with different physiological responses, including embryogenesis, vasculogenesis, and cellular remodeling, as well as different disease pathogenesis. Induced MMP responses are especially associated with cancer metastasis and secondary tumor development through proteolytic cleavage of several ECM and non-ECM proteins. Although both eicosanoids and MMPs are involved with cancer progression and metastasis, the interrelation between these two molecules are less explored. The present review discusses relevant studies that connect eicosanoids and MMPs and highlight the crosstalk between them offering novel therapeutic approach in cancer treatment.

Epoxyeicosanoids prevent intervertebral disc degeneration in vitro and in vivo

Intervertebral disc (IVD) degeneration is considered a common cause of low back pain. In the degenerating IVD, the production of pro-inflammatory cytokines, including IL-1 and TNF-α, progressively increases, contributing to the degenerative process. Epoxyeicosatrienoic acids (EETs), synthesized from arachidonic acid by cytochrome P450 enzymes, act as autocrine and paracrine effectors in regulating inflammation, cardiovascular functions, and angiogenesis. EETs were shown to be especially potent promoters of tissue regeneration. Considering their anti-inflammatory and anti-catabolic potential, we investigated whether EETs can influence IVD degeneration. We found that 14,15-EET protected rat nucleus pulposus (NP) cells against death induced by treatment with H₂O₂and TNF-α in vitro. At the molecular level, 14,15-EET significantly inhibited the NF-κB pathway, which plays essential roles in the degeneration and survival of NP cells. As a result, 14,15-EET efficiently prevented the matrix remodeling response of NP cells to TNF-α. Using a needle-punctured rat tail model, the influence of 14,15-EET on IVD degeneration in vivo was evaluated using radiographs, magnetic resonance images (MRI), and histological analysis. We observed that 14,15-EET prevented IVD degeneration. Our findings demonstrated that 14,15-EET can enhance the survival of NP cells and inhibit IVD degeneration. The EET pathway may be a novel therapeutic target against IVD degeneration.

Association of EPHX2 R287Q Polymorphism with Diabetic Nephropathy in Chinese Type 2 Diabetic Patients

The aim of this study was to investigate the relationship between EPHX2 rs751141 (R287Q polymorphism) and diabetic nephropathy (DN) in Chinese type 2 diabetes (T2D). This case-control study explored the association between EPHX2 rs751141 and DN in a total of 870 Chinese T2D patients (406 T2D patients with DN and 464 T2D patients without DN). DNA was extracted from peripheral leukocytes of the patients and rs751141 was genotyped. The A allele frequency of rs751141 was significantly lower in DN patients (20.94%) compared with non-DN controls (27.8%) (P = 0.001), and the A allele of rs751141 was associated with a significantly lower risk of DN after adjustment for multiple covariates in the additive genetic model (OR = 0.68, 95% CI = 0.52-0.88, P = 0.004). Significant association between rs751141 and homocysteine (Hcy) level on the risk of DN was observed, indicating that in patients with the highest Hcy levels, the A allele showed marked association with lower risk of DN in all three genetic models. In conclusion, the A allele of exonic polymorphism in EPHX2 rs751141 is negatively associated with the incidence of DN in the Chinese T2D population, which could be modulated by Hcy level status.

Synergistic Effect of the MTHFR C677T and EPHX2 G860A Polymorphism on the Increased Risk of Ischemic Stroke in Chinese Type 2 Diabetic Patients

The aim of this study was to investigate the relationship between the combined effect of MTHFR C677T (rs1801133) and EPHX2 G860A (rs751141) polymorphism and ischemic stroke in Chinese T2DM patients. This case-control study included a total of 626 Chinese T2DM patients (236 T2DM patients with ischemic stroke and 390 T2DM patients without ischemic stroke). The rs1801133 and rs751141 were genotyped using real-time polymerase chain reaction. Statistical analysis was performed with SPSS 17.0. Results showed that the combined effect of MTHFR TT and EPHX2 GG or GA + AA genotype has a higher risk of ischemic stroke compared with the control group (combined effect of MTHFR CC and EPHX2 GA + AA genotypes; OR = 3.46 and OR = 3.42, resp.; P = .001 and P = .002, resp.). The A allele showed marked association with a lower risk of ischemic stroke in patients with the lowest Hcy levels under additive, recessive, and dominant genetic models (OR = 0.45, OR = 0.11, and OR = 0.44, resp.; P = .002, P = .035, and P = .008, resp.), which was not observed in medium or high Hcy level groups. In conclusion, the T allele of rs1801133 and the G allele of rs751141 may be risk factors of ischemic stroke in the Chinese T2DM population.

Epoxygenated Fatty Acids Inhibit Retinal Vascular Inflammation

The objective of the present study was to assess the effect of elevating epoxygenated fatty acids on retinal vascular inflammation. To stimulate inflammation we utilized TNFα, a potent pro-inflammatory mediator that is elevated in the serum and vitreous of diabetic patients. In TNFα-stimulated primary human retinal microvascular endothelial cells, total levels of epoxyeicosatrienoic acids (EETs), but not epoxydocosapentaenoic acids (EDPs), were significantly decreased. Exogenous addition of 11,12-EET or 19,20-EDP when combined with 12-(3-adamantane-1-yl-ureido)-dodecanoic acid (AUDA), an inhibitor of epoxide hydrolysis, inhibited VCAM-1 and ICAM-1 expression and protein levels; conversely the diol product of 19,20-EDP hydrolysis, 19,20-DHDP, induced VCAM1 and ICAM1 expression. 11,12-EET and 19,20-EDP also inhibited leukocyte adherence to human retinal microvascular endothelial cell monolayers and leukostasis in an acute mouse model of retinal inflammation. Our results indicate that this inhibition may be mediated through an indirect effect on NFκB activation. This is the first study demonstrating a direct comparison of EET and EDP on vascular inflammatory endpoints, and we have confirmed a comparable efficacy from each isomer, suggesting a similar mechanism of action. Taken together, these data establish that epoxygenated fatty acid elevation will inhibit early pathology related to TNFα-induced inflammation in retinal vascular diseases.

11,12-Epoxyecosatrienoic acids mitigate endothelial dysfunction associated with estrogen loss and aging: Role of membrane depolarization

OBJECTIVE

Endothelial dysfunction, including upregulation of inflammatory adhesion molecules and impaired vasodilatation, is a key element in cardiovascular disease. Aging and estrogen withdrawal in women are associated with endothelial inflammation, vascular stiffness and increased cardiovascular disease. Epoxyecosatrienoic acids (EETs), the products of arachidonic acid metabolism mediated by cytochrome P450 (CYP) 2J, 2C and other isoforms, are regulated by soluble epoxide hydrolase (sEH)-catalyzed conversion into less active diols. We hypothesized that 11,12-EETs would reduce the endothelial dysfunction associated with aging and estrogen loss.

APPROACH/RESULTS

When stabilized by an sEH inhibitor (seHi), 11,12-EET at a physiologically low dose (0.1nM) reduced cytokine-stimulated upregulation of adhesion molecules on human aorta endothelial cells (HAEC) and monocyte adhesion under shear flow through marked depolarization of the HAEC when combined with TNFα. Mechanistically, neither 11,12-EETs nor 17β-estradiol (E2) at physiologic concentrations prevented activation of NFκB by TNFα. E2 at physiological concentrations reduced sEH expression in HAEC, but did not alter CYP expression, and when combined with TNFα depolarized the cell. We also examined vascular dysfunction in adult and aged ovariectomized Norway brown rats (with and without E2 replacement) using an ex-vivo model to analyze endothelial function in an intact segment of artery. sEHi and 11,12-EET with or without E2 attenuated phenylephrine induced constriction and increased endothelial-dependent dilation of aortic rings from ovariectomized rats.

CONCLUSIONS

Increasing 11,12-EETs through sEH inhibition effectively attenuates inflammation and may provide an effective strategy to preserve endothelial function and prevent atherosclerotic heart disease in postmenopausal women.

Identification of protease m1 zinc metalloprotease conferring resistance to deltamethrin by characterization of an AFLP marker in Culex pipiens pallens

BACKGROUND

Continuous and excessive application of deltamethrin (DM) has resulted in the rapid development of insecticide resistance in Culex pipiens pallens. The quantitative trait loci (QTL) responsible for resistance to DM had previously been detected in Cx. pipiens pallens. But locating the QTLs on the chromosomes remained difficult. An available approach is to first characterize DNA molecular markers linked with the phenotype, and then identify candidate genes.

METHODS

In this study, the amplified fragment length polymorphism (AFLP) marker L3A8.177 associated with the QTL, was characterized. We searched for potential candidate genes in the flank region of L3A8.177 in the genome sequence of the closely related Cx. pipiens quinquefasciatus and conducted mRNA expression analysis of the candidate gene via quantitative real-time PCR. Then the relationship between DM resistance and the candidate gene was identified using RNAi and American CDC Bottle Bioassay in vivo. We also cloned the ORF sequences of the candidate gene from both susceptible and resistant mosquitoes.

RESULTS

The genes CYP6CP1 and protease m1 zinc metalloprotease were in the flank region of L3A8.177 and had significantly different expression levels between susceptible and resistant strains. Protease m1 zinc metalloprotease was significantly up-regulated in the susceptible strains compared with the resistant and remained over-expressed in the susceptible field-collected strains. For deduced amino acid sequences of protease m1 zinc metalloprotease, there was no difference between susceptible and resistant mosquitoes. Knockdown of protease m1 zinc metalloprotease not only decreased the sensitivity of mosquitoes to DM in the susceptible strain but also increased the expression of CYP6CP1, suggesting the role of protease m1 zinc metalloprotease in resistance may be involved in the regulation of the P450 gene expression.

CONCLUSION

Our study represents an example of candidate genes derived from the AFLP marker associated with the QTL and provides the first evidence that protease m1 zinc metalloprotease may play a role in the regulation of DM resistance in Cx. pipiens pallens.

Macrophage epoxygenase determines a profibrotic transcriptome signature

Epoxygenases belong to the cytochrome P450 family. They generate epoxyeicosatrienoic acids, which are known to have anti-inflammatory effects, but little is known about their role in macrophage function. By high-throughput sequencing of RNA in primary macrophages derived from rodents and humans, we establish the relative expression of epoxygenases in these cells. Zinc-finger nuclease-mediated targeted gene deletion of the major rat macrophage epoxygenase Cyp2j4 (ortholog of human CYP2J2) resulted in reduced epoxyeicosatrienoic acid synthesis. Cyp2j4(-/-) macrophages have relatively increased peroxisome proliferator-activated receptor-γ levels and show a profibrotic transcriptome, displaying overexpression of a specific subset of genes (260 transcripts) primarily involved in extracellular matrix, with fibronectin being the most abundantly expressed transcript. Fibronectin expression is under the control of epoxygenase activity in human and rat primary macrophages. In keeping with the in vitro findings, Cyp2j4(-/-) rats show upregulation of type I collagen following unilateral ureter obstruction of the kidney, and quantitative proteomics analysis (liquid chromatography-tandem mass spectrometry) showed increased renal type I collagen and fibronectin protein abundance resulting from experimentally induced crescentic glomerulonephritis in these rats. Taken together, these results identify the rat epoxygenase Cyp2j4 as a determinant of a profibrotic macrophage transcriptome that could have implications in various inflammatory conditions, depending on macrophage function.

Epoxyeicosatrienoic acids attenuate cigarette smoke extract-induced interleukin-8 production in bronchial epithelial cells

In response to endothelial cell activation, arachidonic acid can be converted by cytochrome P450 (CYP) epoxygenases to epoxyeicosatrienoic acids (EETs), which have potent vasodilator and anti-inflammatory properties. In this study, we investigated the effects of exogenous EETs on cigarette smoke extract (CSE)-induced inflammation in human bronchial epithelial cells (NCI-H292). We found that CSE inhibited the expression of CYP2C8 and mildly stimulated the expression of epoxide hydrolase 2 (EPHX2) but did not change the expression of CYP2J2. Treatment with 11,12-EET or 14,15-EET attenuated the CSE-induced release of interleukin (IL)-8 by inhibiting the phosphorylation of p38 mitogen-activated protein kinases (MAPKs). Our results demonstrated that CSE may reduce the anti-inflammatory ability of epithelial cells themselves by lowering the EET level. EETs from pulmonary epithelial cells may play a critical protective role on epithelial cell injury.

CYP2J2 overexpression attenuates nonalcoholic fatty liver disease induced by high-fat diet in mice

Cytochrome P-450 epoxygenase-derived epoxyeicosatrienoic acids (EETs) exert diverse biological activities, which include potent vasodilatory, anti-inflammatory, antiapoptotic, and antioxidatant effects, and cardiovascular protection. Liver has abundant epoxygenase expression and high levels of EET production; however, the roles of epoxygenases in liver diseases remain to be elucidated. In this study, we investigated the protection against high-fat diet-induced nonalcoholic fatty liver disease (NAFLD) in mice with endothelial-specific CYP2J2 overexpression (Tie2-CYP2J2-Tr). After 24 wk of high-fat diet, Tie2-CYP2J2-Tr mice displayed attenuated NAFLD compared with controls. Tie2-CYP2J2-Tr mice showed significantly decreased plasma triglyceride levels and liver lipid accumulation, improved liver function, reduced inflammatory responses, and less increase in hepatic oxidative stress than wild-type control mice. These effects were associated with inhibition of NF-κB/JNK signaling pathway activation and enhancement of the antioxidant defense system in Tie2-CYP2J2-Tr mice in vivo. We also demonstrated that 14,15-EET treatment protected HepG2 cells against palmitic acid-induced inflammation and oxidative stress. 14,15-EET attenuated palmitic acid-induced changes in NF-κB/JNK signaling pathways, malondialdehyde generation, glutathione levels, reactive oxygen species production, and NADPH oxidase and antioxidant enzyme expression in HepG2 cells in vitro. Together, these results highlight a new role for CYP epoxygenase-derived EETs in lipotoxicity-related inflammation and oxidative stress and reveal a new molecular mechanism underlying EETs-mediated anti-inflammatory and antioxidant effects that could aid in the design of new therapies for the prevention and treatment of NAFLD.

Genome-wide association mapping of acute lung injury in neonatal inbred mice

Reactive oxygen species (ROS) contribute to the pathogenesis of many acute and chronic pulmonary disorders, including bronchopulmonary dysplasia (BPD), a respiratory condition that affects preterm infants. However, the mechanisms of susceptibility to oxidant stress in neonatal lungs are not completely understood. We evaluated the role of genetic background in response to oxidant stress in the neonatal lung by exposing mice from 36 inbred strains to hyperoxia (95% O2) for 72 h after birth. Hyperoxia-induced lung injury was evaluated by using bronchoalveolar lavage fluid (BALF) analysis and pathology. Statistically significant interstrain variation was found for BALF inflammatory cells and protein (heritability estimates range: 33.6-55.7%). Genome-wide association mapping using injury phenotypes identified quantitative trait loci (QTLs) on chromosomes 1, 2, 4, 6, and 7. Comparative mapping of the chromosome 6 QTLs identified Chrm2 (cholinergic receptor, muscarinic 2, cardiac) as a candidate susceptibility gene, and mouse strains with a nonsynonymous coding single-nucleotide polymorphism (SNP) in Chrm2 that causes an amino acid substitution (P265L) had significantly reduced hyperoxia-induced inflammation compared to strains without the SNP. Further, hyperoxia-induced lung injury was significantly reduced in neonatal mice with targeted deletion of Chrm2, relative to wild-type controls. This study has important implications for understanding the mechanisms of oxidative lung injury in neonates.

Role of cytochrome P450-mediated arachidonic acid metabolites in the pathogenesis of cardiac hypertrophy

A plethora of studies have demonstrated the expression of cytochrome P450 (CYP) and soluble epoxide hydrolase (sEH) enzymes in the heart and other cardiovascular tissues. In addition, the expression of these enzymes is altered during several cardiovascular diseases (CVDs), including cardiac hypertrophy (CH). The alteration in CYP and sEH expression results in derailed CYP-mediated arachidonic acid (AA) metabolism. In animal models of CH, it has been reported that there is an increase in 20-hydroxyeicosatetraenoic acid (20-HETE) and a decrease in epoxyeicosatrienoic acids (EETs). Further, inhibiting 20-HETE production by CYP ω-hydroxylase inhibitors and increasing EET stability by sEH inhibitors have been proven to protect against CH as well as other CVDs. Therefore, CYP-mediated AA metabolites 20-HETE and EETs are potential key players in the pathogenesis of CH. Some studies have investigated the molecular mechanisms by which these metabolites mediate their effects on cardiomyocytes and vasculature leading to pathological CH. Activation of several intracellular signaling cascades, such as nuclear factor of activated T cells, nuclear factor kappa B, mitogen-activated protein kinases, Rho-kinases, Gp130/signal transducer and activator of transcription, extracellular matrix degradation, apoptotic cascades, inflammatory cytokines, and oxidative stress, has been linked to the pathogenesis of CH. In this review, we discuss how 20-HETE and EETs can affect these signaling pathways to result in, or protect from, CH, respectively. However, further understanding of these metabolites and their effects on intracellular cascades will be required to assess their potential translation to therapeutic approaches for the prevention and/or treatment of CH and heart failure.

Roles of the epoxygenase CYP2J2 in the endothelium

Cytochrome p450 (CYP)2J2 is an epoxygenase enzyme that metabolises arachidonic acid to epoxyeicosatrienoic acids (EETs). EETs are inactivated by soluble epoxide hydrolase (sEH), which converts them in to their corresponding dihydroxyeicosatrienoic acids (DHETs). CYP2J2 is highly expressed in cardiovascular tissue including the heart and vascular endothelial cells. CYP2J2 and the EETs it produces have been shown to have a diverse range of effects on the vasculature, including the regulation of inflammation, vascular tone, cellular proliferation, angiogenesis, and metabolism. This review will examine these established and emerging roles of CYP2J2 in the biology of vascular endothelial cells.

Mechanisms of epoxyeicosatrienoic acids to improve cardiac remodeling in chronic renal failure disease

Both clinical and basic science studies have demonstrated that cardiac remodeling in patients with chronic renal failure (CRF) is very common. It is a key feature during the course of heart failure and an important risk factor for subsequent cardiac mortality. Traditional drugs or therapies rarely have effects on cardiac regression of CRF and cardiovascular events are still the first cause of death. Epoxyeicosatrienoic acids (EETs) are the products of arachidonic acids metabolized by cytochrome P450 epoxygenases. It has been found that EETs have important biological effects including anti-hypertension and anti-inflammation. Recent data suggest that EETs are involved in regulating cardiomyocyte injury, renal dysfunction, chronic kidney disease (CKD)-related risk factors and signaling pathways, all of which play key roles in cardiac remodeling induced by CRF. This review analyzes the literature to identify the possible mechanisms for EETs to improve cardiac remodeling induced by CRF and indicates the therapeutic potential of EETs in it.

Chronic doxorubicin cardiotoxicity modulates cardiac cytochrome P450-mediated arachidonic acid metabolism in rats

Doxorubicin [(DOX) Adriamycin] is an effective anticancer agent whose major limiting side effect is cardiotoxicity. This cardiotoxicity is predicted only by the cumulative dose of DOX where the clinical situation involves chronic drug administration. Therefore, we investigate the effect of chronic DOX cardiotoxicity on expression of the cardiac cytochrome P450 (P450) enzymes and arachidonic acid (AA) metabolism in male Sprague-Dawley (SD) rats. The chronic toxicity was induced by multiple intraperitoneal injections for a cumulative dose of 15 mg/kg divided into six injections within 2 weeks. After 14 days of the last injection, the heart, liver, and kidney were harvested, and the expression of different genes was determined by real-time polymerase chain reaction. In addition, microsomal protein from the heart was prepared and incubated with AA. Thereafter, different AA metabolites were analyzed by liquid chromatography-electrospray ionization-mass spectrometry. The chronic DOX cardiotoxicity significantly induced gene expression of hypertrophic markers, apoptotic markers, CYP2E1, CYP4A3, CYP4F1, CYP4F5, and soluble epoxide hydrolase (sEH) enzyme, which was accompanied by an increase in the activity of P450 ω-hydroxylases and sEH. In addition, both the sEH inhibitor, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid, and the ω-hydroxylase inhibitor, N-hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (HET0016), significantly prevented the DOX-mediated induction of the hypertrophic markers in the cardiac-derived H9c2 cells, which further confirms the role of these enzymes in DOX cardiotoxicity. Furthermore, gene expression of P450 and sEH was altered in an organ-specific manner. As a result, the chronic DOX administration leads to an imbalance between P450-mediated cardiotoxic and cardioprotective pathways. Therefore, P450 ω-hydroxylases and sEH might be considered as novel targets to prevent and/or treat DOX cardiotoxicity.

Homocysteine upregulates soluble epoxide hydrolase in vascular endothelium in vitro and in vivo

RATIONALE

Hyperhomocysteinemia is a risk factor of atherogenesis. Soluble epoxide hydrolase (sEH) is a major enzyme that hydrolyzes epoxyeicosatrienoic acids and attenuates their cardiovascular protective effects. Whether homocysteine (Hcy) regulates sEH and the underlying mechanism remains elusive.

OBJECTIVE

To elucidate the mechanism by which Hcy regulates sEH expression and endothelial activation in vitro and in vivo.

METHODS AND RESULTS

Hcy treatment in cultured human endothelial cells dose-dependently and time-dependently upregulated sEH mRNA and protein. Hcy increased the expression of adhesion molecules, which was markedly reversed by inhibiting sEH activity. Hcy-induced sEH upregulation is associated with activation of activating transcription factor-6 (ATF6). Bioinformatics analysis revealed a putative ATF6-binding motif in the promoter region of the sEH gene, which was found at a methylation site. Site-directed mutagenesis and chromatin immunoprecipitation assays demonstrated that Hcy treatment or ATF6 overexpression promoted ATF6 binding to the promoter of sEH and increased its activity. Results of methylation-specific polymerase chain reaction revealed that the ATF6 binding site on the sEH promoter was partially methylated and was demethylated with Hcy. SiRNA knockdown of ATF6α or SP1 blocked and ATF6 overexpression and DNA methyltransferase inhibitor mimicked the effect of homocysteine on sEH upregulation. In vivo, immunofluorescence assay revealed elevated expression of sEH and adhesion molecules in the aortic intima of mice with mild hyperhomocysteinemia, which was attenuated by sEH deletion or inhibition.

CONCLUSION

ATF6 activation and DNA demethylation may coordinately contribute to Hcy-induced sEH expression and endothelial activation. Inhibition of sEH may be a therapeutic approach for treating Hcy-induced cardiovascular diseases.

Reno-protective mechanisms of epoxyeicosatrienoic acids in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of mortality worldwide, and it is well known that end-stage renal disease (ESRD) is a profound consequence of the progression of CVD. Present treatments only slow CVD progression to ESRD, and it is imperative that new therapeutic strategies are developed to prevent the incidence of ESRD. Because epoxyeicosatrienoic acids (EETs) have been shown to elicit reno-protective effects in hypertensive animal models, the current review will focus on addressing the reno-protective mechanisms of EETs in CVD. The cytochrome P-450 epoxygenase catalyzes the oxidation of arachidonic acid to EETs. EETs have been identified as endothelium-derived hyperpolarizing factors (EDHFs) with vasodilatory, anti-inflammatory, antihypertensive, and antiplatelet aggregation properties. EETs also have profound effects on vascular migration and proliferation and promote angiogenesis. The progression of CVD has been linked to decreased EETs levels, leading to the concept that EETs should be therapeutically targeted to prevent end-organ damage associated with CVD. However, EETs are quickly degraded by the enzyme soluble epoxide hydrolase (sEH) to their less active diols, dihydroxyeicosatrienoic acids (DHETs). As such, one way to increase EETs level is to inhibit their degradation to DHETs by using sEH inhibitors. Inhibition of sEH has been shown to effectively reduce blood pressure and organ damage in experimental models of CVD. Another approach to target EETs is to develop EET analogs with improved solubility and resistance to auto-oxidation and metabolism by sEH. For example, stable ether EET analogs dilate afferent arterioles and lower blood pressure in hypertensive rodent animal models. EET agonists also improve insulin signaling and vascular function in animal models of metabolic syndrome.

The roles of CYP450 epoxygenases and metabolites, epoxyeicosatrienoic acids, in cardiovascular and malignant diseases

Cytochrome P450 (CYP) epoxygenases metabolize arachidonic acid to biologically active eicosanoids. The primary epoxidation products are four regioisomers of cis-epoxyeicosatrienoic acid (EET): 5,6-, 8,9-, 11,12-, and 14,15-EET. CYP2J2, CYP2C8, and CYP2C9 are the predominant epoxygenase isoforms involved in EET formation. CYP2J and CYP2C gene families in humans are abundantly expressed in the endothelium, myocardium, and kidney. The cardiovascular effects of CYP epoxygenases and EETs range from vasodilation, anti-hypertension, pro-angiogenesis, anti-atherosclerosis, and anti-inflammation to anti-injury caused by ischemia-reperfusion. Using transgenic animals for in vivo analyses of CYP epoxygenases revealed comprehensive and marked cardiovascular protective effects. In contrast, CYP epoxygenases and their metabolites, EETs, are upregulated in human tumors and promote tumor progression and metastasis. These biological effects result from the anti-apoptosis, pro-mitogenesis, and anti-migration roles of CYP epoxygenases and EETs at the cellular level. Importantly, soluble epoxide hydrolase (sEH) inhibitors are anti-hypertensive and anti-inflammatory and, therefore, protect the heart from damage, whereas the terfenadine-related, specific inhibitors of CYP2J2 exhibit strong anti-tumor activity in vitro and in vivo. Thus, CYP2J2 and arachidonic acid-derived metabolites likely play important roles in regulating cardiovascular functions and malignancy under physiological and/or pathological conditions. Moreover, although challenges remain to improving the drug-like properties of sEH inhibitors and identifying efficient ways to deliver sEH inhibitors, sEH will likely become an important therapeutic target for cardiovascular diseases. In addition, CYP2J2 may be a therapeutic target for treating human cancers and leukemia.

Regulation of endothelial cell functions by basement membrane- and arachidonic acid-derived products

Angiogenesis, the formation of new blood vessels from preexisting vasculature, is required for normal physiological as well as pathological events. The angiogenic process requires endothelial cells to proliferate, migrate, and undergo tubulogenesis. These multistep processes necessitate secretion of pro-angiogenic growth factors, activation of specific intracellular signaling, and interaction of endothelial cells with basement membrane (BM) extracellular matrix components. The generation and release of angiogenic molecules are highly regulated and are influenced by numerous factors, including BM-derived fragments, proteolytic enzymes, as well as metabolites of arachidonic acid (AA). The interactions between these key modulators of angiogenesis is extremely complex, as AA metabolites can regulate the synthesis of soluble angiogenic factors, BM components, as well as enzymes capable of cleaving BM components, which result in the generation of pro- and/or anti-angiogenic products. Furthermore, some BM-derived fragments can alter the expression of AA-converting enzymes and consequently the synthesis of angiogenic factors. In this review we describe the relationship between BM components and AA metabolites with respect to the regulation of endothelial cell functions in health and disease.

Endothelial CYP epoxygenase overexpression and soluble epoxide hydrolase disruption attenuate acute vascular inflammatory responses in mice

Cytochrome P-450 (CYP)-derived epoxyeicosatrienoic acids (EETs) possess potent anti-inflammatory effects in vitro. However, the effect of increased CYP-mediated EET biosynthesis and decreased soluble epoxide hydrolase (sEH, Ephx2)-mediated EET hydrolysis on vascular inflammation in vivo has not been rigorously investigated. Consequently, we characterized acute vascular inflammatory responses to endotoxin in transgenic mice with endothelial expression of the human CYP2J2 and CYP2C8 epoxygenases and mice with targeted disruption of Ephx2. Compared to wild-type controls, CYP2J2 transgenic, CYP2C8 transgenic, and Ephx2(-/-) mice each exhibited a significant attenuation of endotoxin-induced activation of nuclear factor (NF)-κB signaling, cellular adhesion molecule, chemokine and cytokine expression, and neutrophil infiltration in lung in vivo. Furthermore, attenuation of endotoxin-induced NF-κB activation and cellular adhesion molecule and chemokine expression was observed in primary pulmonary endothelial cells isolated from CYP2J2 and CYP2C8 transgenic mice. This attenuation was inhibited by a putative EET receptor antagonist and CYP epoxygenase inhibitor, directly implicating CYP epoxygenase-derived EETs with the observed anti-inflammatory phenotype. Collectively, these data demonstrate that potentiation of the CYP epoxygenase pathway by either increased endothelial EET biosynthesis or globally decreased EET hydrolysis attenuates NF-κB-dependent vascular inflammatory responses in vivo and may serve as a viable anti-inflammatory therapeutic strategy.

Profile of lipid and protein autacoids in diabetic vitreous correlates with the progression of diabetic retinopathy

OBJECTIVE

This study was aimed at obtaining a profile of lipids and proteins with a paracrine function in normal and diabetic vitreous and exploring whether the profile correlates with retinal pathology.

RESEARCH DESIGN AND METHODS

Vitreous was recovered from 47 individuals undergoing vitreoretinal surgery: 16 had nonproliferative diabetic retinopathy (NPDR), 15 had proliferative diabetic retinopathy, 7 had retinal detachments, and 9 had epiretinal membranes. Protein and lipid autacoid profiles were determined by protein arrays and mass spectrometry-based lipidomics.

RESULTS

Vitreous lipids included lipoxygenase (LO)- and cytochrome P450 epoxygenase (CYP)-derived eicosanoids. The most prominent LO-derived eicosanoid was 5-hydroxyeicosate traenoic acid (HETE), which demonstrated a diabetes-specific increase (P = 0.027) with the highest increase in NPDR vitreous. Vitreous also contained CYP-derived epoxyeicosatrienoic acids; their levels were higher in nondiabetic than diabetic vitreous (P < 0.05). Among inflammatory, angiogenic, and angiostatic cytokines and chemokines, only vascular endothelial growth factor (VEGF) showed a significant diabetes-specific profile (P < 0.05), although a similar trend was noted for tumor necrosis factor (TNF)-alpha. Soluble VEGF receptors R1 and R2 were detected in all samples with lowest VEGF-R2 levels (P < 0.05) and higher ratio of VEGF to its receptors in NPDR and PDR vitreous.

CONCLUSIONS

This study is the first to demonstrate diabetes-specific changes in vitreous lipid autacoids including arachidonate and docosahexanoate-derived metabolites indicating an increase in inflammatory versus anti-inflammatory lipid mediators that correlated with increased levels of inflammatory and angiogenic proteins, further supporting the notion that inflammation plays a role the pathogenesis of this disease.

Vascular pharmacology of epoxyeicosatrienoic acids

Epoxyeicosatrienoic acids (EETs) are cytochrome P450 metabolites of arachidonic acid that are produced by the vascular endothelium in responses to various stimuli such as the agonists acetylcholine (ACH) or bradykinin or by shear stress which activates phospholipase A(2) to release arachidonic acid. EETs are important regulators of vascular tone and homeostasis. In the modulation of vascular tone, EETs function as endothelium-derived hyperpolarizing factors (EDHFs). In models of vascular inflammation, EETs attenuate inflammatory signaling pathways in both the endothelium and vascular smooth muscle. Likewise, EETs regulate blood vessel formation or angiogenesis by mechanisms that are still not completely understood. Soluble epoxide hydrolase (sEH) converts EETs to dihydroxyeicosatrienoic acids (DHETs) and this metabolism limits many of the biological actions of EETs. The recent development of inhibitors of sEH provides an emerging target for pharmacological manipulation of EETs. Additionally, EETs may initiate their biological effects by interacting with a cell surface protein that is a G protein-coupled receptor (GPCR). Since GPCRs represent a common target of most drugs, further characterization of the EET receptor and synthesis of specific EET agonists and antagonist can be used to exploit many of the beneficial effects of EETs in vascular diseases, such as hypertension and atherosclerosis. This review will focus on the current understanding of the contribution of EETs to the regulation of vascular tone, inflammation, and angiogenesis. Furthermore, the therapeutic potential of targeting the EET pathway in vascular disease will be highlighted.

Cytochrome P450 epoxygenases, soluble epoxide hydrolase, and the regulation of cardiovascular inflammation

The cytochrome P450 (CYP) epoxygenase enzymes CYP2J and CYP2C catalyze the epoxidation of arachidonic acid to epoxyeicosatrienoic acids (EETs), which are rapidly hydrolyzed to dihydroxyeicosatrienoic acids (DHETs) by soluble epoxide hydrolase (sEH). It is well-established that CYP epoxygenase-derived EETs possess potent vasodilatory effects; however, the cellular effects of EETs and their regulation of various inflammatory processes have become increasingly appreciated in recent years, suggesting that the role of this pathway in the cardiovascular system extends beyond the maintenance of vascular tone. In particular, CYP epoxygenase-derived EETs inhibit endothelial activation and leukocyte adhesion via attenuation of nuclear factor-kappaB activation, inhibit hemostasis, protect against myocardial ischemia-reperfusion injury, and promote endothelial cell survival via modulation of multiple cell signaling pathways. Thus, the CYP epoxygenase pathway is an emerging target for pharmacological manipulation to enhance the cardiovascular protective effects of EETs. This review will focus on the role of the CYP epoxygenase pathway in the regulation of cardiovascular inflammation and (1) describe the functional impact of CYP epoxygenase-derived EET biosynthesis and sEH-mediated EET hydrolysis on key inflammatory process in the cardiovascular system, (2) discuss the potential relevance of this pathway to pathogenesis and treatment of cardiovascular disease, and (3) identify areas for future research.

Role of copper and homocysteine in pressure overload heart failure

Elevated levels of homocysteine (Hcy) (known as hyperhomocysteinemia HHcy) are involved in dilated cardiomyopathy. Hcy chelates copper and impairs copper-dependent enzymes. Copper deficiency has been linked to cardiovascular disease. We tested the hypothesis that copper supplement regresses left ventricular hypertrophy (LVH), fibrosis and endothelial dysfunction in pressure overload DCM mice hearts. The mice were grouped as sham, sham + Cu, aortic constriction (AC), and AC + Cu. Aortic constriction was performed by transverse aortic constriction. The mice were treated with or without 20 mg/kg copper supplement in the diet for 12 weeks. The cardiac function was assessed by echocardiography and electrocardiography. The matrix remodeling was assessed by measuring matrix metalloproteinase (MMP), tissue inhibitor of metalloproteinases (TIMPs), and lysyl oxidase (LOX) by Western blot analyses. The results suggest that in AC mice, cardiac function was improved with copper supplement. TIMP-1 levels decreased in AC and were normalized in AC + Cu. Although MMP-9, TIMP-3, and LOX activity increased in AC and returned to baseline value in AC + Cu, copper supplement showed no significant effect on TIMP-4 activity after pressure overload. In conclusion, our data suggest that copper supplement helps improve cardiac function in a pressure overload dilated cardiomyopathic heart.

Homocysteine effects classical pathway of GPCR down regulation: Galpha(q/11), Galpha(12/13), G(i/o)

G protein-coupled receptors (GPCRs) are known to modulate intracellular effectors involved in cardiac function. We recently reported homocysteine (Hcy)-induced ERK-phosphorylation was suppressed by pertussis toxin (PTX), which suggested the involvement of GPCRs in initiating signal transduction. An activated GPCR undergoes down regulation via a known mechanism involving ERK, GRK2, beta-arrestin1: ERK activity increases; GRK2 activity increases; beta-arrestin1 is degraded. We hypothesized that Hcy treatment leads to GPCR activation and down regulation. Microvascular endothelial cells were treated with Hcy. Expression of phospho-ERK1 and phospho-GRK2 was determined using Western blot, standardized to ERK1, GRK2, and beta-actin. Hcy was shown to dephosphorylate GRK2, thereby enhancing the activity. The results provided further evidence that Hcy acts as an agonist to activate GPCRs, followed by their down regulation. Hcy was also shown to decrease the content of the following G proteins and other proteins: beta-arrestin1, Galpha(q/11), Galpha(12/13), G(i/o).