miR-31 Overexpression Exacerbates Atherosclerosis by Targeting NOX4 in apoE(-/-) Mice

BACKGROUND

Increasing evidence has shown that microRNAs are involved in apoptosis in different cells. However, the role of miR-31 in atherosclerosis (AS) has never been elucidated. In the present study, we identified the impact of miR-31 on atherosclerosis in macrophages.

METHODS

The level of miR-31 in macrophages was examined in apoE-/- mice. Cell viability and apoptosis were examined in macrophage cells transfected with miR-31 mimics, inhibitors or negative control. In addition, the impact of NOX4 on cell apoptosis was tested with a specific siRNA targeting NADPH oxidase 4 (NOX4).

RESULTS

An enhanced level of miR-31 was found in macrophage cells of apoE-/- mice, suggesting that miR-31 might contribute to abnormal cell proliferation of macrophage cells. Upregulation of miR-31 decreased cell viability and induced macrophage cell apoptosis. Moreover, knockdown of NOX4 reduced cell migration capacity and enhanced cell apoptosis.

CONCLUSIONS

The current data suggested that miR-31 contributed to macrophage apoptosis by regulating the expression of NOX4.

Inhibition of breast cancer invasion by TIS21/BTG2/Pc3-Akt1-Sp1-Nox4 pathway targeting actin nucleators, mDia genes

The mammalian homolog of Drosophila diaphanous (mDia), actin nucleator, has been known to participate in the process of invasion and metastasis of cancer cells via regulating a number of actin-related biological processes. We have previously reported that tumor suppressor TIS21(/BTG2/Pc3) (TIS21) inhibits invadopodia formation by downregulating reactive oxygen species (ROS) in MDA-MB-231 cells. We herein report that TIS21(/BTG2/Pc3) downregulates diaphanous-related formin (DRF) expression via reducing NADPH oxidase 4 (Nox4)-derived ROS generation by Akt1 activation and subsequently impairs invasion activity of the highly invasive breast cancer cells. Knockdown of Akt1 by RNA interference recovered the TIS21(/BTG2/Pc3)-inhibited F-actin remodeling and ROS generation by recovering Nox4 expression. Furthermore, Sp1-mediated Nox4 transcription was downregulated by TIS21(/BTG2/Pc3)-Akt1 signals, leading to the inhibition of cancer cell invasion via F-actin remodeling by mDia genes. To our best knowledge, this is the first study to show that TIS21(/BTG2/Pc3)-Akt1 inhibited Sp1-Nox4-ROS cascade, subsequently reducing invasion activity via inhibition of mDia family genes.

Puerarin Improves Diabetic Aorta Injury by Inhibiting NADPH Oxidase-Derived Oxidative Stress in STZ-Induced Diabetic Rats

OBJECTIVE

Puerarin is a natural flavonoid isolated from the TCM lobed kudzuvine root. This study investigated the effect and mechanisms of puerarin on diabetic aorta in rats.

METHODS

Streptozotocin- (STZ-) induced diabetic rats were administered with puerarin for 3 weeks. Levels of serum insulin (INS), PGE2, endothelin (ET), glycated hemoglobin (GHb), H2O2, and nitric oxide (NO) in rats were measured by ELISA and colorimetric assay kits. The aortas were stained with H&E. Moreover, the mRNA expression of ICAM-1, LOX-1, NADPH oxidase 2 (NOX2), and NOX4 and the protein expression of ICAM-1, LOX-1, NF-κB p65, E-selectin, NOX2, and NOX4 in aorta tissues were measured by real-time PCR and Western blot, respectively. The localization of ICAM-1, NF-κB p65, NOX2, and NOX4 in the aorta tissues was also determined through immunohistochemistry.

RESULTS

Puerarin treatment exerted no effect on fasting blood glucose levels but significantly reduced the serum levels of INS, GHb, PGE2, ET, H2O2, and NO. In addition, puerarin improved the pathological alterations and inhibited the expression of ICAM-1, LOX-1, NOX2, and NOX4 at both mRNA and protein levels. Puerarin also significantly reduced the number of cells showing positive staining for ICAM-1, NOX2, NOX4, and NF-κB p65.

CONCLUSION

Puerarin demonstrated protective effect on the STZ-induced diabetic rat aorta. The protective mechanisms may include regulation of NF-κB and inhibition of NOX2 and NOX4 followed by inhibition of cell adhesion molecule expression.

Oxidative stress promotes benign prostatic hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH) is characterized by increased tissue mass in the transition zone of the prostate, which leads to obstruction of urine outflow and significant morbidity in the majority of older men. Plasma markers of oxidative stress are increased in men with BPH but it is unclear whether oxidative stress and/or oxidative DNA damage are causal in the pathogenesis of BPH.

METHODS

Levels of 8-OH deoxyguanosine (8-OH dG), a marker of oxidative stress, were measured in prostate tissues from normal transition zone and BPH by ELISA. 8-OH dG was also detected in tissues by immunohistochemistry and staining quantitated by image analysis. Nox4 promotes the formation of reactive oxygen species. We therefore created and characterized transgenic mice with prostate specific expression of Nox4 under the control of the prostate specific ARR2PB promoter.

RESULTS

Human BPH tissues contained significantly higher levels of 8-OH dG than control transition zone tissues and the levels of 8-OH dG were correlated with prostate weight. Cells with 8-OH dG staining were predominantly in the epithelium and were present in a patchy distribution. The total fraction of epithelial staining with 8-OH dG was significantly increased in BPH tissues by image analysis. The ARR2PB-Nox4 mice had increased oxidative DNA damage in the prostate, increased prostate weight, increased epithelial proliferation, and histological changes including epithelial proliferation, stromal thickening, and fibrosis when compared to wild type controls.

CONCLUSIONS

Oxidative stress and oxidative DNA damage are important in the pathogenesis of BPH.

Endothelial NADPH oxidase 4 protects ApoE-/- mice from atherosclerotic lesions

Vascular reactive oxygen species (ROS) are known to be involved in atherosclerosis development and progression. NADPH oxidase 4 (Nox4) is a constitutively active ROS-producing enzyme that is highly expressed in the vascular endothelium. Nox4 is unique in its biology and has been implicated in vascular repair, however, the role of Nox4 in atherosclerosis is unknown. Therefore, to determine the effect of endothelial Nox4 on development of atherosclerosis, Apoe E-/- mice +/- endothelial Nox4 (ApoE-/- + EC Nox4) were fed a high cholesterol/high fat (Western) diet for 24 weeks. Significantly fewer atherosclerotic lesions were observed in the ApoE-/- + EC Nox4 mice as compared to the ApoE-/- littermates, which was most striking in the abdominal region of the aorta. In addition, markers of T cell populations were markedly different between the groups; T regulatory cell marker (FoxP3) was increased whereas T effector cell marker (T-bet) was decreased in aorta from ApoE-/- + EC Nox4 mice compared to ApoE-/- alone. We also observed decreased monokine induced by gamma interferon (MIG; CXCL9), a cytokine known to recruit and activate T cells, in plasma and tissue from ApoE-/- + EC Nox4 mice. To further investigate the link between endothelial Nox4 and MIG expression, we utilized cultured endothelial cells from our EC Nox4 transgenic mice and human cells with adenoviral overexpression of Nox4. In these cultured cells, upregulation of Nox4 attenuated endothelial cell MIG expression in response to interferon-gamma. Together these data suggest that endothelial Nox4 expression reduces MIG production and promotes a T cell distribution that favors repair over inflammation, leading to protection from atherosclerosis.

NADPH oxidase 4 regulates homocysteine metabolism and protects against acetaminophen-induced liver damage in mice

Glutathione is the major intracellular redox buffer in the liver and is critical for hepatic detoxification of xenobiotics and other environmental toxins. Hepatic glutathione is also a major systemic store for other organs and thus impacts on pathologies such as Alzheimer's disease, Sickle Cell Anaemia and chronic diseases associated with aging. Glutathione levels are determined in part by the availability of cysteine, generated from homocysteine through the transsulfuration pathway. The partitioning of homocysteine between remethylation and transsulfuration pathways is known to be subject to redox-dependent regulation, but the underlying mechanisms are not known. An association between plasma Hcy and a single nucleotide polymorphism within the NADPH oxidase 4 locus led us to investigate the involvement of this reactive oxygen species- generating enzyme in homocysteine metabolism. Here we demonstrate that NADPH oxidase 4 ablation in mice results in increased flux of homocysteine through the betaine-dependent remethylation pathway to methionine, catalysed by betaine-homocysteine-methyltransferase within the liver. As a consequence NADPH oxidase 4-null mice display significantly lowered plasma homocysteine and the flux of homocysteine through the transsulfuration pathway is reduced, resulting in lower hepatic cysteine and glutathione levels. Mice deficient in NADPH oxidase 4 had markedly increased susceptibility to acetaminophen-induced hepatic injury which could be corrected by administration of N-acetyl cysteine. We thus conclude that under physiological conditions, NADPH oxidase 4-derived reactive oxygen species is a regulator of the partitioning of the metabolic flux of homocysteine, which impacts upon hepatic cysteine and glutathione levels and thereby upon defence against environmental toxins.

[Losartan regulates oxidative stress via caveolin-1 and NOX4 in mice with ventilator- induced lung injury]

OBJECTIVE

To investigate the effect of losartan in regulating oxidative stress and the underlying mechanism in mice with ventilator-induced lung injury.

METHODS

Thirty-six male C57 mice were randomly divided into control group, losartan treatment group, mechanical ventilation model group, and ventilation plus losartan treatment group. After the corresponding treatments, the lung injuries in each group were examined and the expressions of caveolin-1 and NOX4 in the lung tissues were detected.

RESULTS

The mean Smith score of lung injury was significantly higher in mechanical ventilation model group (3.3) than in the control group (0.4), and losartan treatment group (0.3); the mean score was significantly lowered in ventilation plus losartan treatment group (2.3) compared with that in the model group (P<0.05). The expressions of caveolin-1 and NOX4 were significantly higher in the model group than in the control and losartan treatment groups (P<0.05) but was obviously lowered after losartan treatment (P<0.05). Co-expression of caveolin-1 and NOX4 in the lungs was observed in the model group, and was significantly decreased after losartan treatment.

CONCLUSION

Losartan can alleviate ventilator-induced lung injury in mice and inhibit the expression of caveolin-1 and NOX4 and their interaction in the lungs.

NOX4-dependent Hydrogen peroxide promotes shear stress-induced SHP2 sulfenylation and eNOS activation

Laminar shear stress (LSS) triggers signals that ultimately result in atheroprotection and vasodilatation. Early responses are related to the activation of specific signaling cascades. We investigated the participation of redox-mediated modifications and in particular the role of hydrogen peroxide (H2O2) in the sulfenylation of redox-sensitive phosphatases. Exposure of vascular endothelial cells to short periods of LSS (12 dyn/cm(2)) resulted in the generation of superoxide radical anion as detected by the formation of 2-hydroxyethidium by HPLC and its subsequent conversion to H2O2, which was corroborated by the increase in the fluorescence of the specific peroxide sensor HyPer. By using biotinylated dimedone we detected increased total protein sulfenylation in the bovine proteome, which was dependent on NADPH oxidase 4 (NOX4)-mediated generation of peroxide. Mass spectrometry analysis allowed us to identify the phosphatase SHP2 as a protein susceptible to sulfenylation under LSS. Given the dependence of FAK activity on SHP2 function, we explored the role of FAK under LSS conditions. FAK activation and subsequent endothelial NO synthase (eNOS) phosphorylation were promoted by LSS and both processes were dependent on NOX4, as demonstrated in lung endothelial cells isolated from NOX4-null mice. These results support the idea that LSS elicits redox-sensitive signal transduction responses involving NOX4-dependent generation of hydrogen peroxide, SHP2 sulfenylation, and ulterior FAK-mediated eNOS activation.

Role of Hyperketonemia in Inducing Oxidative Stress and Cellular Damage in Cultured Hepatocytes and Type 1 Diabetic Rat Liver

BACKGROUND/AIMS

Type 1 diabetic (T1D) patients have a higher incidence of liver disease. T1D patients frequently experience elevated plasma ketone levels along with hyperglycemia. However, no study has examined whether hyperketonemia per se has any role in excess liver damage in T1D. This study investigates the hypothesis that hyperketonemia can induce oxidative stress and cellular dysfunction.

METHODS

STZ treated diabetic rats, FL83B hepatocytes, and GCLC knocked down (GSH deficient) hepatocytes were used.

RESULTS

The blood levels of ALT and AST, biomarkers of liver damage, and ketones were elevated in T1D rats. An increase in NOX4 and ROS along with a reduction in GSH and GCLC levels was observed in T1D rat livers in comparison to those seen in non-diabetic control or type 2 diabetic rats. MCP-1 and ICAM-1 were also elevated in T1D rat livers and ketone treated hepatocytes. Macrophage markers CCR2 and CD11A that interact with MCP-1, and ICAM-1 respectively, were also elevated in the T1D liver, indicating macrophage infiltration. Additionally, activated macrophages increased hepatocyte damage with ketone treatment, which was similar to that seen in GCLC knockdown hepatocytes without ketones.

CONCLUSION

Hyperketonemia per se can induce macrophage mediated damage to hepatocytes and the liver, caused by GSH depletion and oxidative stress up regulation in T1D.

Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) Promotes Angiogenesis and Ischemia-Induced Neovascularization Via NADPH Oxidase 4 (NOX4) and Nitric Oxide-Dependent Mechanisms

BACKGROUND

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has the ability to inhibit angiogenesis by inducing endothelial cell death, as well as being able to promote pro-angiogenic activity in vitro. These seemingly opposite effects make its role in ischemic disease unclear. Using Trail(-/-) and wildtype mice, we sought to determine the role of TRAIL in angiogenesis and neovascularization following hindlimb ischemia.

METHODS AND RESULTS

Reduced vascularization assessed by real-time 3-dimensional Vevo ultrasound imaging and CD31 staining was evident in Trail(-/-) mice after ischemia, and associated with reduced capillary formation and increased apoptosis. Notably, adenoviral TRAIL administration significantly improved limb perfusion, capillary density, and vascular smooth-muscle cell content in both Trail(-/-) and wildtype mice. Fibroblast growth factor-2, a potent angiogenic factor, increased TRAIL expression in human microvascular endothelial cell-1, with fibroblast growth factor-2-mediated proliferation, migration, and tubule formation inhibited with TRAIL siRNA. Both fibroblast growth factor-2 and TRAIL significantly increased NADPH oxidase 4 (NOX4) expression. TRAIL-inducible angiogenic activity in vitro was inhibited with siRNAs targeting NOX4, and consistent with this, NOX4 mRNA was reduced in 3-day ischemic hindlimbs of Trail(-/-) mice. Furthermore, TRAIL-induced proliferation, migration, and tubule formation was blocked by scavenging H2O2, or by inhibiting nitric oxide synthase activity. Importantly, TRAIL-inducible endothelial nitric oxide synthase phosphorylation at Ser-1177 and intracellular human microvascular endothelial cell-1 cell nitric oxide levels were NOX4 dependent.

CONCLUSIONS

This is the first report demonstrating that TRAIL can promote angiogenesis following hindlimb ischemia in vivo. The angiogenic effect of TRAIL on human microvascular endothelial cell-1 cells is downstream of fibroblast growth factor-2, involving NOX4 and nitric oxide signaling. These data have significant therapeutic implications, such that TRAIL may improve the angiogenic response to ischemia and increase perfusion recovery in patients with cardiovascular disease and diabetes.

Endosomal gene expression: a new indicator for prostate cancer patient prognosis?

Prostate cancer continues to be a major cause of morbidity and mortality in men, but a method for accurate prognosis in these patients is yet to be developed. The recent discovery of altered endosomal biogenesis in prostate cancer has identified a fundamental change in the cell biology of this cancer, which holds great promise for the identification of novel biomarkers that can predict disease outcomes. Here we have identified significantly altered expression of endosomal genes in prostate cancer compared to non-malignant tissue in mRNA microarrays and confirmed these findings by qRT-PCR on fresh-frozen tissue. Importantly, we identified endosomal gene expression patterns that were predictive of patient outcomes. Two endosomal tri-gene signatures were identified from a previously published microarray cohort and had a significant capacity to stratify patient outcomes. The expression of APPL1, RAB5A, EEA1, PDCD6IP, NOX4 and SORT1 were altered in malignant patient tissue, when compared to indolent and normal prostate tissue. These findings support the initiation of a case-control study using larger cohorts of prostate tissue, with documented patient outcomes, to determine if different combinations of these new biomarkers can accurately predict disease status and clinical progression in prostate cancer patients.

NADPH Oxidase Accounts for Changes in Cerebrovascular Redox Status in Hindlimb Unweighting Rats

OBJECTIVE

The roles of cerebrovascular oxidative stress in vascular functional remodeling have been described in hindlimb-unweighting (HU) rats. However, the underlying mechanism remains to be established.

METHODS

We investigated the generation of vascular reactive oxygen species (ROS), Nox2/Nox4 protein and mRNA levels, NADPH oxidase activity, and manganese superoxide dismutase (MnSOD) and glutathione peroxidase-1 (GPx-1) mRNA levels in cerebral and mesenteric smooth muscle cells (VSMCs) of HU rats.

RESULTS

ROS production increased in cerebral but not in mesenteric VSMCs of HU rats compared with those in control rats. Nox2 and Nox4 protein and mRNA levels were increased significantly but MnSOD/GPx-1 mRNA levels decreased in HU rat cerebral arteries but not in mesenteric arteries. NADPH oxidases were activated significantly more in cerebral but not in mesenteric arteries of HU rats. NADPH oxidase inhibition with apocynin attenuated cerebrovascular ROS production and partially restored Nox2/Nox4 protein and mRNA levels, NADPH oxidase activity, and MnSOD/GPx-1 mRNA levels in cerebral VSMCs of HU rats.

CONCLUSION

These results suggest that vascular NADPH oxidases regulate cerebrovascular redox status and participate in vascular oxidative stress injury during simulated microgravit.

Glycated human serum albumin induces NF-κB activation and endothelial nitric oxide synthase uncoupling in human umbilical vein endothelial cells

AIMS

Non-enzymatic glycated proteins could mediate diabetes vascular complications, but the molecular mechanisms are unknown. Our objective was to find new targets involved in the glycated human serum albumin (gHSA)-enhanced extracellular reactive oxygen species (ROS) production in human endothelial cells.

METHODS & RESULTS

Some nuclear factors and phosphorylation cascades were analysed. gHSA activated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), which up-regulated NOX4 and P22PHOX and enhanced ROS production. Pharmacological inhibition of NF-κB reversed gHSA-enhanced NOX4 expression and decreased gHSA-induced ROS production in extra- and intracellular spaces. The inhibition of activator protein-1 (AP-1) induced a rise in NOX4 and P22PHOX subunit expression and a down-regulation of endothelial nitric oxide synthase (eNOS). AP-1 inhibition also enhanced extracellular ROS production in the presence of serum albumin, but not with gHSA. These results were explained by the eNOS uncoupling induced by gHSA, also demonstrated in this study. Phosphatidylinositol 3-kinase or mitogen-activated protein kinase kinase 1/2 did not show to be involved in gHSA-induced ROS production.

CONCLUSIONS

All together, the results suggested that gHSA-enhanced ROS production in endothelium is mediated by: 1) NF-κB activation and subsequence up-regulation of NADPH oxidase, 2) eNOS uncoupling. AP-1, although is not directly affected by gHSA, is another target for regulating NADPH oxidase and eNOS expression in endothelial cells.

Tanshinone IIA blocks dexamethasone-induced apoptosis in osteoblasts through inhibiting Nox4-derived ROS production

Apoptosis of osteoblasts caused by glucocorticoids has been identified as an important contributor to the development of osteoporosis. Tanshinone IIA (Tan), an active ingredient extracted from the rhizome of the Salvia miltiorrhiza Bunge (Danshen), has been reported to cast positive effects on osteoporosis. However, the precise mechanisms accounting this action remain elusive. In this study, by using osteoblastic MC3T3-E1 cells as a model, we confirmed the protective effects of Tan against dexamethasone (Dex)-induced cell apoptosis and further clarified its molecular mechanism of action. Our results showed that treatment with Dex caused cell injury, increased cytosol cytochrome c level and Nox expression, induced apoptosis in caspase-9-dependent manner, and enhanced reactive oxygen species (ROS) production. Tan attenuated these deleterious consequence triggered by Dex. Moreover, Dex-induced ROS production and cell injury were inhibited by antioxidant, NADPH oxidases inhibitors, Nox4 inhibitor, and Nox4 small interfering RNA (siRNA). Overexpression of Nox4 almost abolished the inhibitory effect of Tan on Dex-induced cell injury and apoptosis. The results also demonstrated significant involvement of Nox4 in the Dex-induced apoptosis. Nox4-derived ROS led to apoptosis through activation of intrinsic mitochondrial pathway. Additionally, we evidenced that Tan reversed Dex-induced apoptosis via inactivation of Nox4. The present findings suggest that inhibition of Nox4 may be a novel therapeutic approach of Tan to prevent against glucocorticoids-induced osteoblasts apoptosis and osteoporosis.

Dermal delivery of HSP47 siRNA with NOX4-modulating mesoporous silica-based nanoparticles for treating fibrosis

Fibrotic diseases such as scleroderma have been linked to increased oxidative stress and upregulation of pro-fibrotic genes. Recent work suggests a role of NADPH oxidase 4 (NOX4) and heat shock protein 47 (HSP47) in inducing excessive collagen synthesis, leading to fibrotic diseases. Herein, we elucidate the relationship between NOX4 and HSP47 in fibrogenesis and propose to modulate them altogether as a new strategy to treat fibrosis. We developed a nanoparticle platform consisting of polyethylenimine (PEI) and polyethylene glycol (PEG) coating on a 50-nm mesoporous silica nanoparticle (MSNP) core. The nanoparticles effectively delivered small interfering RNA (siRNA) targeting HSP47 (siHSP47) in an in vitro model of fibrosis based on TGF-β stimulated fibroblasts. The MSNP core also imparted an antioxidant property by scavenging reactive oxygen species (ROS) and subsequently reducing NOX4 levels in the in vitro fibrogenesis model. The nanoparticle was far superior to n-acetyl cysteine (NAC) at modulating pro-fibrotic markers. In vivo evaluation was performed in a bleomycin-induced scleroderma mouse model, which shares many similarities to human scleroderma disease. Intradermal administration of siHSP47-nanoparticles effectively reduced HSP47 protein expression in skin to normal level. In addition, the antioxidant MSNP also played a prominent role in reducing the pro-fibrotic markers, NOX4, alpha smooth muscle actin (α-SMA), and collagen type I (COL I), as well as skin thickness of the mice.

Targeting mitochondrial reactive oxygen species to modulate hypoxia-induced pulmonary hypertension

Pulmonary hypertension (PH) is characterized by increased pulmonary vascular remodeling, resistance, and pressures. Reactive oxygen species (ROS) contribute to PH-associated vascular dysfunction. NADPH oxidases (Nox) and mitochondria are major sources of superoxide (O(2)(•-)) and hydrogen peroxide (H(2)O(2)) in pulmonary vascular cells. Hypoxia, a common stimulus of PH, increases Nox expression and mitochondrial ROS (mtROS) production. The interactions between these two sources of ROS generation continue to be defined. We hypothesized that mitochondria-derived O(2)(•-) (mtO(2)(•-)) and H(2)O(2) (mtH(2)O(2)) increase Nox expression to promote PH pathogenesis and that mitochondria-targeted antioxidants can reduce mtROS, Nox expression, and hypoxia-induced PH. Exposure of human pulmonary artery endothelial cells to hypoxia for 72 h increased mtO(2)(•-) and mtH(2)O(2). To assess the contribution of mtO(2)(•-) and mtH(2)O(2) to hypoxia-induced PH, mice that overexpress superoxide dismutase 2 (Tg(hSOD2)) or mitochondria-targeted catalase (MCAT) were exposed to normoxia (21% O(2)) or hypoxia (10% O(2)) for three weeks. Compared with hypoxic control mice, MCAT mice developed smaller hypoxia-induced increases in RVSP, α-SMA staining, extracellular H(2)O(2) (Amplex Red), Nox2 and Nox4 (qRT-PCR and Western blot), or cyclinD1 and PCNA (Western blot). In contrast, Tg(hSOD2) mice experienced exacerbated responses to hypoxia. These studies demonstrate that hypoxia increases mtO(2)(•-) and mtH(2)O(2). Targeting mtH(2)O(2) attenuates PH pathogenesis, whereas targeting mtO(2)(•-) exacerbates PH. These differences in PH pathogenesis were mirrored by RVSP, vessel muscularization, levels of Nox2 and Nox4, proliferation, and H(2)O(2) release. These studies suggest that targeted reductions in mtH(2)O(2) generation may be particularly effective in preventing hypoxia-induced PH.

[Effect of bile duct ligation and recanalization on rat hepatocyte epithelial-mesenchymal phenotype and NOX4 protein expression]

OBJECTIVE

To observe epithelial-mesenchymal phenotypes and oxidative stress related protein expressions of the liver cells in a rat model of liver fibrosis induced by bile duct ligation and recanalization.

METHODS

Twenty-four male Wistar rats were randomized into 4 groups, including a sham-operated group, two bile duct ligation groups with ligation for 2 and 4 weeks, and a bile duct ligation group with a 2-week ligation followed by a 2-week recanalization. HE staining and Masson staining were used to assess liver fibrosis in the rats, and immunohistochemistry and Western blotting were employed to detect expressions of the epithelial and mesenchymal marker proteins and oxidative stress-related proteins.

RESULTS

Compared with the sham-operated group, the rats with bile duct ligation showed obvious liver fibrosis, which worsened as the ligation time extended, accompanied by significantly increased expression of α-SMA, collagen I, NOX(4) and vimetin and reduced E-cadherin expression. Compared with the rats with bile duct ligation for 4 weeks, the rats in bile duct ligation-recanalization group showed obviously lessened liver fibrosis, significantly lowered expressions of NOX(4) and mesenchymal cell maker proteins, and enhanced expressions of epithelial cell marker proteins.

CONCLUSION

Bile duct ligation up-regulates mesenchymal phenotype-related proteins and NOX(4) protein expression and down-regulates the expression of epithelial phenotype-related proteins, and these changes can be reversed by subsequent bile duct recanalization.

[Effect of chrysin on expression of NOX4 and NF-κB in right ventricle of monocrotaline-induced pulmonary arterial hypertension of rats]

The aim of the present study is to investigate the protective effect of chrysin (5,7-dihydroxyflavone) on right ventricular remodeling in a rat model of monocrotaline-induced pulmonary arterial hypertension (PAH). PAH rats were induced by a single injection of monocrotaline (60 mg x kg(-1), sc) and were administered with chrysin (50 or 100 mg x kg(-1) x d(-1)) for 4 weeks. At the end of experiment, the right ventricular systolic pressure (RVSP) and mean pulmonary artery pressure (mPAP) were monitored via the right jugular vein catheterization into the right ventricle. Right ventricle (RV) to left ventricle (LV) + septum (S) and RV to tibial length were calculated. Right ventricular morphological change was observed by HE staining. Masson's trichrome stain was used to demonstrate collagen deposition. The total antioxidative capacity (T-AOC) and malondialdehyde (MDA) levels in right ventricle were determined according to the manufacturer's instructions. The expressions of collagen I, collagen III, NADPH oxidase 4 (NOX4) and nuclear factor-kappa B (NF-κB) were analyzed by immunohistochemisty, qPCR and (or) Western blot. The results showed that chrysin treatment for 4 weeks attenuated RVSP, mPAP and right ventricular remodeling index (RV/LV+S and RV/Tibial length) of PAH rats induced by monocrotaline. Furthermore, monocrotaline-induced right ventricular collagen accumulation and collagen I and collagen III expression were both significantly suppressed by chrysin. The expressions of NOX4, NF-κB and MDA contents were obviously decreased, while the T-AOC was significantly increased in right ventricule from PAH rats with chrysin treatment. These results suggest that chrysin ameliorates right ventricular remodeling of PAH induced by monocrotaline in rats through its down-regulating of NOX4 expression and antioxidant activity, and inhibiting NF-κB expression and collagen accumulation.

MCPIP is induced by cholesterol and participated in cholesterol-caused DNA damage in HUVEC

Hypercholesterolemia is an important risk factor for atherosclerosis and cholesterol treatment would cause multiple damages, including DNA damage, on endothelial cells. In this work, we have used human umbilical vein endothelial cell line (HUVEC) to explore the mechanism of cholesterol induced damage. We have found that cholesterol treatment on HUVEC could induce the expression of MCPIP1. When given 12.5 mg/L cholesterol on HUVEC, the expression of MCPIP1 starts to increase since 4 hr after treatment and at 24 hr after treatment it could reach to 10 fold of base line level. We hypothesis this induction of MCPIP1 may contribute to the damaging process and we have used siRNA of MCPIP1 in further research. This MCPIP1 siRNA (siMCPIP) could down regulate MCPIP1 by 73.4% and when using this siRNA on HUVECs, we could see the cholesterol induced DNA damage have been reduced. We have detected DNA damage by γH2AX foci formation in nuclear, γH2AX protein level and COMET assay. Compare to cholesterol alone group, siMCPIP group shows much less γH2AX foci formation in nuclear after cholesterol treatment, less γH2AX protein level in cell and also less tail moment detected in COMET assay. We have also seen that using siMCPIP1 could result in less reactive oxygen species (ROS) in cell after cholesterol treatment. We have also seen that using siMCPIP could reduce the protein level of Nox4 and p47(phox), two major regulators in ROS production. These results suggest that MCPIP1 may play an important role in cholesterol induced damage.

[Relationship between expression of endothelial nitric oxide synthase and NADPH oxidase in lungs of mice exposed to chronic hypoxia]

OBJECTIVE

To explore the relationship between the expression of endothelial nitric oxide synthase (eNOS) and NADPH oxidase (NOX) in the lungs of mice treated by chronic hypoxic exposure.

METHODS

Thirty male wild-type (WT) C57Bl/6 mice and thirty male eNOS-knockout (KO) C57BL/6 mice were randomly divided into normoxic groups (exposed to normoxia for 7 days or 21 days), hypoxic groups (exposed to 10% oxygen for 7 days or 21 days), and treatment groups (exposed to 10% oxygen and orally administrated 10 mmol/L 4-hydroxy TEMPO in drinking water for 7 days or 21 days) (n=6 in each group). The remodeling of the small pulmonary arteries was evaluated by the percentage of media wall thickness (MT%). The weight ratio of right ventricle to left ventricle plus septum (RV/[LV+S]) was calculated to evaluate the hypertrophy of right ventricle. Real-time PCR was used to measure the mRNA expression of NOX2, NOX4, and eNOS in mouse lungs. ELISA was used to determine the concentration of reactive oxygen species (ROS) in mouse lungs.

RESULTS

In WT mice and KO mice, the hypoxic groups had significantly increased pulmonary vascular remodeling and RV/[LV+S] compared with the normoxic and treatment groups (P<0.05), but there were no significant differences between the normoxic and treatment groups (P>0.05). In WT mice, the hypoxic and treatment groups had significantly lower ROS concentrations than the normoxic group (P<0.05), but there were no significant differences between the hypoxic and treatment groups (P>0.05). In WT mice, the mRNA expression of eNOS, NOX2, and NOX4 was significantly higher in the hypoxic group than in the normoxic group (P<0.05), and 4-hydroxy TEMPO reversed their over-expression. In the normoxic group, the KO mice had significantly higher NOX2 and NOX4 mRNA expression than the WT mice (P<0.05); in KO mice, the hypoxic group showed no significant changes in NOX4 mRNA expression (P>0.05), but had significantly reduced NOX2 mRNA expression (P<0.05), as compared with the normoxic group; the treatment group had reduced expression of NOX2 mRNA expression and increased NOX4 mRNA expression (P<0.05), as compared with the hypoxic group.

CONCLUSIONS

eNOS plays a key role in the regulation of expression of NOX2 and NOX4 in the lungs exposed to hypoxia. It suggests that NOX and eNOS may physically interact with one another in pulmonary vascular remodeling induced by chronic hypoxia.

Nox4-dependent activation of cofilin mediates VSMC reorientation in response to cyclic stretching

Vascular smooth muscle cells (VSMCs) are subjected to various types of mechanical forces within the vessel wall. Although it is known that VSMCs undergo cell body reorientation in response to mechanical stimulation, how this mechanical stretch is transduced within the cell into biochemical signals causing cytoskeleton reorganization remains unclear. Cofilin, a protein that controls actin dynamics, is activated by Slingshot phosphatase-dependent serine 3 dephosphorylation by redox-dependent mechanisms. Nox4 is a main source of reactive oxygen species (ROS) in the vessel wall that localizes in association with the cytoskeleton. Therefore, we hypothesize that Nox4 mediates redox-dependent activation of cofilin, which is required for cytoskeletal reorganization and cell reorientation after mechanical stimulation. In this study, we found that mechanical stretch stimulates ROS production in VSMCs and that the signaling that leads to cell reorientation requires hydrogen peroxide but not superoxide. Indeed, mechanical stretch induces cofilin activation and stretch-induced cytoskeletal reorganization, and cell reorientation is inhibited in cells where cofilin activity has been downregulated. Importantly, Nox4-deficient cells fail to activate cofilin and to undergo cell reorientation, a phenotype rescued by the expression of a constitutively active cofilin mutant. Our results demonstrate that in VSMCs mechanical stimulation activates cofilin by a Nox4-dependent mechanism and that this pathway is required for cytoskeleton reorganization and cell reorientation.

A bioinformatic and mechanistic study elicits the antifibrotic effect of ursolic acid through the attenuation of oxidative stress with the involvement of ERK, PI3K/Akt, and p38 MAPK signaling pathways in human hepatic stellate cells and rat liver

NADPH oxidases (NOXs) are a predominant mediator of redox homeostasis in hepatic stellate cells (HSCs), and oxidative stress plays an important role in the pathogenesis of liver fibrosis. Ursolic acid (UA) is a pentacyclic triterpenoid with various pharmacological activities, but the molecular targets and underlying mechanisms for its antifibrotic effect in the liver remain elusive. This study aimed to computationally predict the molecular interactome and mechanistically investigate the antifibrotic effect of UA on oxidative stress, with a focus on NOX4 activity and cross-linked signaling pathways in human HSCs and rat liver. Drug-drug interaction via chemical-protein interactome tool, a server that can predict drug-drug interaction via chemical-protein interactome, was used to predict the molecular targets of UA, and Database for Annotation, Visualization, and Integrated Discovery was employed to analyze the signaling pathways of the predicted targets of UA. The bioinformatic data showed that there were 611 molecular proteins possibly interacting with UA and that there were over 49 functional clusters responding to UA. The subsequential benchmarking data showed that UA significantly reduced the accumulation of type I collagen in HSCs in rat liver, increased the expression level of MMP-1, but decreased the expression level of TIMP-1 in HSC-T6 cells. UA also remarkably reduced the gene expression level of type I collagen in HSC-T6 cells. Furthermore, UA remarkably attenuated oxidative stress via negative regulation of NOX4 activity and expression in HSC-T6 cells. The employment of specific chemical inhibitors, SB203580, LY294002, PD98059, and AG490, demonstrated the involvement of ERK, PI3K/Akt, and p38 MAPK signaling pathways in the regulatory effect of UA on NOX4 activity and expression. Collectively, the antifibrotic effect of UA is partially due to the oxidative stress attenuating effect through manipulating NOX4 activity and expression. The results suggest that UA may act as a promising antifibrotic agent. More studies are warranted to evaluate the safety and efficacy of UA in the treatment of liver fibrosis.

Deficiency of NOX1 or NOX4 Prevents Liver Inflammation and Fibrosis in Mice through Inhibition of Hepatic Stellate Cell Activation

Reactive oxygen species (ROS) produced by nicotinamide adenine dinucleotide phosphate oxidase (NOX) play a key role in liver injury and fibrosis. Previous studies demonstrated that GKT137831, a dual NOX1/4 inhibitor, attenuated liver fibrosis in mice as well as pro-fibrotic genes in hepatic stellate cells (HSCs) as well as hepatocyte apoptosis. The effect of NOX1 and NOX4 deficiency in liver fibrosis is unclear, and has never been directly compared. HSCs are the primary myofibroblasts in the pathogenesis of liver fibrosis. Therefore, we aimed to determine the role of NOX1 and NOX4 in liver fibrosis, and investigated whether NOX1 and NOX4 signaling mediates liver fibrosis by regulating HSC activation. Mice were treated with carbon tetrachloride (CCl₄) to induce liver fibrosis. Deficiency of either NOX1 or NOX4 attenuates liver injury, inflammation, and fibrosis after CCl₄ compared to wild-type mice. NOX1 or NOX4 deficiency reduced lipid peroxidation and ROS production in mice with liver fibrosis. NOX1 and NOX4 deficiency are approximately equally effective in preventing liver injury in the mice. The NOX1/4 dual inhibitor GKT137831 suppressed ROS production as well as inflammatory and proliferative genes induced by lipopolysaccharide (LPS), platelet-derived growth factor (PDGF), or sonic hedgehog (Shh) in primary mouse HSCs. Furthermore, the mRNAs of proliferative and pro-fibrotic genes were downregulated in NOX1 and NOX4 knock-out activated HSCs (cultured on plastic for 5 days). Finally, NOX1 and NOX4 protein levels were increased in human livers with cirrhosis compared with normal controls. Thus, NOX1 and NOX4 signaling mediates the pathogenesis of liver fibrosis, including the direct activation of HSC.

Transforming growth factor β-interacting factor-induced malignant progression of hepatocellular carcinoma cells depends on superoxide production from Nox4

Hepatocellular carcinoma (HCC) is one of the most deadly malignancies worldwide because of its high recurrence rate, high metastatic potential, and resistance to drugs. Elucidation of the mechanisms underlying malignancy in HCC is needed to improve diagnosis, therapy, and prognosis. Previously, we showed that transforming growth factor β-interacting factor (TGIF) antagonizes arsenic trioxide-induced apoptosis of HepG2 cells and is associated with poor prognosis and progression of urothelial carcinoma in patients after radical nephroureterectomy. To determine whether TGIF plays a role in HCC tumorigenesis, we compared the expression of TGIF, its downstream targets, and reactive oxygen species levels between HCC HepG2 cells and the more invasive SK-Hep1 cells. Superoxide production, phosphorylation of c-Src(Y416) and AKT(S473), and expression of TGIF and NADPH oxidase (Nox) were higher in invasive SK-Hep1 cells than in HepG2 cells. TGIF-overexpressing HepG2 xenograft tumors markedly promoted tumor growth and metastasis to the lungs. Overexpression of TGIF in HepG2 cells increased superoxide production from Nox4, matrix metalloproteinase expression, invadopodia formation, and cellular migration/invasion ability. Conversely, knockdown of TGIF in SK-Hep1 cells attenuated these processes. Using gene knockdown and pharmacological inhibitors, we demonstrate that c-Src/AKT is the upstream signaling that regulates TGIF-induced Nox4 activation and subsequent superoxide production. Taken together, our results implicate TGIF as a potential biomarker for prognosis and target for clinical therapy in patients with advanced HCC.

Nox4 Is Dispensable for Exercise Induced Muscle Fibre Switch

Introduction

By producing H₂O₂, the NADPH oxidase Nox4 is involved in differentiation of mesenchymal cells. Exercise alters the composition of slow and fast twitch fibres in skeletal. Here we hypothesized that Nox4 contributes to exercise-induced adaptation such as changes in muscle metabolism or muscle fibre specification and studied this in wildtype and Nox4-/- mice.

Results

Exercise, as induced by voluntary running in a running wheel or forced running on a treadmill induced a switch from fast twitch to intermediate fibres. However the induced muscle fibre switch was similar between Nox4-/- and wildtype mice. The same held true for exercise-induced expression of PGC1α or AMPK activation. Both are increased in response to exercise, but with no difference was observed between wildtype and Nox4-/- mice.

Conclusion

Thus, exercise-induced muscle fibre switch is Nox4-independent.