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Heme Oxygenase (heme + oxygenase)
Selected AbstractsAntioxidant and Vasodilatory Effects of Heme Oxygenase on Mesenteric Vasoreactivity Following Chronic HypoxiaMICROCIRCULATION, Issue 2 2009KAREN SWEAZEA ABSTRACT Objective: Chronic hypoxia (CH) results in impaired vasoconstriction associated with increased expression of heme oxygenase (HO). We hypothesized that enhanced HO activity minimizes reactive oxygen species (ROS) in arteries from CH rats, thereby normalizing endothelium-dependent vasodilation and concurrently produces carbon monoxide (CO), resulting in tonic vasodilation. Methods: ROS were quantified in mesenteric arteries from control and CH Sprague-Dawley rats. Reactivity to the endothelium-dependent vasodilator, acetylcholine (ACh), and the vasoconstrictor, phenylephrine (PE), were also assessed. Results: Basal ROS levels did not differ between groups and were similarly increased by HO inhibition. In contrast, catalase inhibition increased ROS in CH rats only. Vasodilatory responses to ACh were not different between groups. Combined inhibition of catalase and HO impaired PE-induced vasoconstriction in both groups. CH-induced impairment of vasoconstriction was reversed by either catalase or HO inhibition supporting the protective roles of the HO and catalase pathways following CH. Increased vascular smooth muscle calcium was observed with inhibition in the CH group, suggesting that catalase and HO-derived CO elicit reduced calcium influx, leading to the impaired vasoconstriction. Conclusions: Our data suggest that although the HO pathway is an important antioxidant influence, impaired vasoconstriction following CH appears to be due to effects of ROS and HO-derived CO. [source] Role of Vascular Heme Oxygenase in Reduced Myogenic Reactivity Following Chronic HypoxiaMICROCIRCULATION, Issue 2 2006JAY S. NAIK ABSTRACT Objective: Exposure to chronic hypoxia (CH) results in a persistent endothelium-dependent vascular smooth muscle hyperpolarization that diminishes vasoconstrictor reactivity. Experiments were performed to test the hypothesis that products of both cytochrome P450 epoxygenase (CYP) and heme oxygenase (HO) are required for the persistent diminished myogenic reactivity following CH. Methods: The authors examined myogenic responses of mesenteric arteries isolated from control and CH (48 h; PB = 380 mmHg) rats in the presence of a HO inhibitor (zinc protoporphyrin IX; ZnPPIX) or combined HO and CYP epoxygenase inhibition (sulfaphenazole). Arteries were isolated and cannulated and the vascular smooth muscle was loaded with the Ca2 + indicator Fura-2. Results: Control vessels maintained their internal diameter in response to step increases in intraluminal pressure, whereas arteries from CH animals passively distended. ZnPPIX augmented myogenic reactivity and [Ca2 +] in arteries from CH animals. Combined administration of sulfaphenazole and ZnPPIX did not have an additional effect compared to ZnPPIX alone. Myogenic reactivity in control vessels was not altered by ZnPPIX or ZnPPIX + sulfaphenazole. Conclusions: HO appears to play a role in regulating myogenic reactivity following CH. Furthermore, these data suggest that products of HO and CYP are both required for the observed attenuation in vasoreactivity following CH. [source] Molecular Responses to Stress Induced in Normal Human Caucasian Melanocytes in Culture by Exposure to Simulated Solar UV,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005Laurent Marrot ABSTRACT Melanocytes play a central role in the response of skin to sunlight exposure. They are directly involved in UV-induced pigmentation as a defense mechanism. However, their alteration can lead to melanoma, a process where the role of sun overexposure is highly probable. The transformation process whereby UV damage may result in melanoma initiation is poorly understood, especially in terms of UV-induced genotoxicity in pigmented cells, where melanin can act either as a sunscreen or as a photosensitizer. The aim of this study was to analyze the behavior of melanocytes from fair skin under irradiation mimicking environmental sunlight in terms of spectral power distribution. To do this, normal human Caucasian melanocytes in culture were exposed to simulated solar UV (SSUV, 300,400 nm). Even at relatively high doses (until 20 min exposure, corresponding to 12 kJ/m2 UV-B and 110 kJ/m2 UV-A), cell death was limited, as shown by cell viability and low occurrence of apoptosis (caspase-3 activation). Moreover, p53 accumulation was three times lower in melanocytes than in unpigmented cells such as fibroblasts after SSUV exposure. However, an important fraction of melanocyte population was arrested in G2-M phase, and this correlated well with a high induction level of the gene GADD45, 4 h after exposure. Among the genes involved in DNA repair, gene XPC was the most inducible because its expression increased more than two-fold 15 h after a 20 min exposure, whereas expression of P48 was only slightly increased. In addition, an early induction of Heme Oxygenase 1 (HO1) gene, a typical response to oxidative stress, was also observed for the first time in melanocytes. Interestingly, this induction remained significant when melanocytes were exposed to UV-A radiation only (320,400 nm), and stimulation of melanogenesis before irradiation further increased HO1 induction. These results were obtained with normal human cells after exposure to SSUV radiation, which mimicked natural sunlight. They provide new data related to gene expression and suggest that melanin in light skin could contribute to sunlight-induced genotoxicity and maybe to melanocyte transformation. [source] Heme Oxygenase (HO)-1 Is Upregulated in the Nasal Mucosa With Allergic Rhinitis,THE LARYNGOSCOPE, Issue 3 2006Ahmed Elhini MD Abstract Background: Heme oxygenase (HO) is considered to be an antioxidant enzyme that catabolizes heme to produce carbon monoxide (CO) and biliverdin. Three isoforms of HO have been discovered. Recently, HO-1 has been found to be upregulated after allergic inflammations of the lower airway. Objective: The objective of this study was to address the expression of HO isoenzymes 1 and 2 in the nasal mucosa of patients with allergic rhinitis as well as normal control subjects. Methods: Nasal mucosa from 30 patients with persistent allergic rhinitis as well as from 10 normal volunteers was used in this study. We used immunofluorescent technique, Western blotting, and real-time quantitative polymerase chain reaction to localize and quantify the expression of these isoenzymes in normal and allergic human nasal tissues. Results: We found that HO-1 is expressed in the epithelial cells of seromucinous glands and macrophages with significant upregulation of its glandular expression in allergic rhinitis but with no difference in its macrophage expression between the study groups in contrast to HO-2 that is expressed in the vascular endothelial lining cells as well as macrophages with no marked difference between the study groups. Conclusion: We demonstrated that expression of HO-1, but not HO-2, was upregulated within the nasal tissues in allergic rhinitis inflammation, and understanding the induction of HO-1 expression may provide for better management of allergic rhinitis that involves oxidative stress. [source] Down-regulation of heme oxygenase-2 is associated with the increased expression of heme oxygenase-1 in human cell linesFEBS JOURNAL, Issue 23 2006Yuanying Ding Intracellular heme concentrations are maintained in part by heme degradation, which is catalyzed by heme oxygenase. Heme oxygenase consists of two structurally related isozymes, HO-1 and HO-2. Recent studies have identified HO-2 as a potential oxygen sensor. To gain further insights into the regulatory role of HO-2 in heme homeostasis, we analyzed the expression profiles of HO-2 and the biochemical consequences of HO-2 knockdown with specific short interfering RNA (siRNA) in human cells. Both HO-2 mRNA and protein are expressed in the eight human cancer cell lines examined, and HO-1 expression is detectable in five of the cell lines, including HeLa cervical cancer and HepG2 hepatoma. Down-regulation of HO-2 expression with siRNA against HO-2 (siHO-2) caused induction of HO-1 expression at both mRNA and protein levels in HeLa and HepG2 cells. In contrast, knockdown of HO-1 expression did not noticeably influence HO-2 expression. HO-2 knockdown prolonged the half-life of HO-1 mRNA twofold in HeLa cells. Transient transfection assays in HeLa cells revealed that the 4.5-kb human HO-1 gene promoter was activated with selective knockdown of HO-2 in a sequence-dependent manner. Moreover, HO-2 knockdown caused heme accumulation in HeLa and HepG2 cells only when exposed to exogenous hemin. HO-2 knockdown may mimic a certain physiological change that is important in the maintenance of cellular heme homeostasis. These results suggest that HO-2 may down-regulate the expression of HO-1, thereby directing the co-ordinated expression of HO-1 and HO-2. [source] Biliverdin therapy protects rat livers from ischemia and reperfusion injuryHEPATOLOGY, Issue 6 2004Constantino Fondevila Heme oxygenase (HO-1) provides a cellular defense mechanism during oxidative stress and catalyzes the rate-limiting step in heme metabolism that produces biliverdin (BV). The role of BV and its potential use in preventing ischemia/reperfusion injury (IRI) had never been studied. This study was designed to explore putative cytoprotective functions of BV during hepatic IRI in rat liver models of ex vivo perfusion and orthotopic liver transplantation (OLT) after prolonged periods of cold ischemia. In an ex vivo hepatic IRI model, adjunctive BV improved portal venous blood flow, increased bile production, and decreased hepatocellular damage. These findings were correlated with amelioration of histological features of IRI, as assessed by Suzuki's criteria. Following cold ischemia and syngeneic OLT, BV therapy extended animal survival from 50% in untreated controls to 90% to 100%. This effect correlated with improved liver function and preserved hepatic architecture. Additionally, BV adjuvant after OLT decreased endothelial expression of cellular adhesion molecules (P-selectin and intracellular adhesion molecule 1), and decreased the extent of infiltration by neutrophils and inflammatory macrophages. BV also inhibited expression of inducible nitric oxide synthase and proinflammatory cytokines (interleukin 1,, tumor necrosis factor ,, and interleukin 6) in OLTs. Finally, BV therapy promoted an increased expression of antiapoptotic molecules independently of HO-1 expression, consistent with BV being an important mediator through which HO-1 prevents cell death. In conclusion, this study documents and dissects potent cytoprotective effects of BV in well-established rat models of hepatic IRI. Our results provide the rationale for a novel therapeutic approach using BV to maximize the function and thus the availability of donor organs. (HEPATOLOGY 2004;40:1333,1341.) [source] Inhibition of heme oxygenase-1 by zinc protoporphyrin IX reduces tumor growth of LL/2 lung cancer in C57BL miceINTERNATIONAL JOURNAL OF CANCER, Issue 3 2007Kaeko Hirai Abstract Heme oxygenase (HO)-1 is a key player reducing cytotoxicity and enhancing protumoral effects of nitric oxide (NO). We examined zinc protoporphyrin (ZnPP) IX, an HO-1 inhibitor, to affect tumor growth of LL/2 mouse lung cancer cells. ZnPPIX reduced HO-1 expression and HO activity in LL/2 cells, whereas cobalt PPIX (CoPPIX), an HO-1 activator, increased both. LL/2 cells treated with sodium nitropurusside, an NO donor, showed growth inhibition dose-dependently, which was enhanced by ZnPPIX cotreatment, but was reduced by CoPPIX. In mice tumors, ZnPPIX decreased HO-1 expression. LL/2-tumors were found in 88% (7/8) vehicle-treated mice, whereas tumors were found in 38% (3/8) and 25% (2/8) mice treated with 5 and 20 ,g/mouse ZnPPIX, respectively (p = 0.0302). Tumor growth was inhibited dose-dependently by ZnPPIX. Vascular endothealial growth factor concentration in tumors was reduced by ZnPPIX (p = 0.0341). Microvessel density (MVD) in ZnPPIX-treated tumors was lower than that in vehicle-treated tumors (p = 0.0362). Apoptotic cell count in ZnPPIX-treated tumors was higher than that in vehicle-treated tumors (p = 0.0003). In contrast, CoPPIX treatment increased HO-1 expression, enhanced tumorigenicity and MVD and reduced apoptosis. From these findings, inhibition of HO-1 by ZnPPIX provides relevant antitumoral effects. © 2006 Wiley-Liss, Inc. [source] Immunohistochemical analysis of heme oxygenase-1 in preneoplastic and neoplastic lesions during chemical hepatocarcinogenesis,INTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2004Fabiana Caballero Summary Heme oxygenase (HO) breaks down the pro-oxidant heme into carbon monoxide, iron and the antioxidant biliverdin. The isoform HO-1 plays an effective role to counteract oxidative damage and to control inflammation. Prolonged cellular damage due to chronic inflammation is one of the reasons leading to the development of tumours. The aim of this work was to investigate HO-1 expression and localization along the different stages of chemically induced hepatocarcinogenesis (HCC) and the occurring morphological changes. To provoke sustained oxidative stress and chronic inflammation, CF1 mice received dietary p -dimethylaminoazobenzene (DAB, 0.5%, w/w) during a whole period of 14 months. HO-1 expression increased along the experimental trial in morphologically normal hepatocytes in DAB-treated animals. HO-1 expression diminished in altered hepatic foci (AHF) and oval cells and early preneoplastic lesions. Otherwise, marked HO-1 overexpression was detected in Kupffer cells and macrophages surrounding necrotic and nodular areas. Adenomas showed decreased HO-1 immunostaining. In hepatocellular carcinomas, an inverse relationship was found between the immunohistochemical expression of HO-1 and the degree of tumour differentiation, being negative in poorly differentiated tumours. In our experimental model, down modulation of HO-1 expression correlated with malignancy progression. Thus, our data point to activation of HO-1 as a potential therapeutic tool. [source] Heme Oxygenase (HO)-1 Is Upregulated in the Nasal Mucosa With Allergic Rhinitis,THE LARYNGOSCOPE, Issue 3 2006Ahmed Elhini MD Abstract Background: Heme oxygenase (HO) is considered to be an antioxidant enzyme that catabolizes heme to produce carbon monoxide (CO) and biliverdin. Three isoforms of HO have been discovered. Recently, HO-1 has been found to be upregulated after allergic inflammations of the lower airway. Objective: The objective of this study was to address the expression of HO isoenzymes 1 and 2 in the nasal mucosa of patients with allergic rhinitis as well as normal control subjects. Methods: Nasal mucosa from 30 patients with persistent allergic rhinitis as well as from 10 normal volunteers was used in this study. We used immunofluorescent technique, Western blotting, and real-time quantitative polymerase chain reaction to localize and quantify the expression of these isoenzymes in normal and allergic human nasal tissues. Results: We found that HO-1 is expressed in the epithelial cells of seromucinous glands and macrophages with significant upregulation of its glandular expression in allergic rhinitis but with no difference in its macrophage expression between the study groups in contrast to HO-2 that is expressed in the vascular endothelial lining cells as well as macrophages with no marked difference between the study groups. Conclusion: We demonstrated that expression of HO-1, but not HO-2, was upregulated within the nasal tissues in allergic rhinitis inflammation, and understanding the induction of HO-1 expression may provide for better management of allergic rhinitis that involves oxidative stress. [source] Heme oxygenase-1/p21WAF1 mediates peroxisome proliferator-activated receptor-, signaling inhibition of proliferation of rat pulmonary artery smooth muscle cellsFEBS JOURNAL, Issue 6 2010Manxiang Li Activation of peroxisome proliferator-activated receptor (PPAR)-, suppresses proliferation of rat pulmonary artery smooth muscle cells (PASMCs), and therefore ameliorates the development of pulmonary hypertension in animal models. However, the molecular mechanisms underlying this effect remain largely unknown. This study addressed this issue. The PPAR, agonist rosiglitazone dose-dependently stimulated heme oxygenase (HO)-1 expression in PASMCs, 5 ,m rosiglitazone inducing a 12.1-fold increase in the HO-1 protein level. Cells pre-exposed to rosiglitazone showed a dose-dependent reduction in proliferation in response to serotonin; this was abolished by pretransfection of cells with sequence-specific small interfering RNA against HO-1. In addition, rosiglitazone stimulated p21WAF1 expression in PASMCs, a 2.34-fold increase in the p21WAF1 protein level being achieved with 5 ,m rosiglitazone; again, this effect was blocked by knockdown of HO-1. Like loss of HO-1, loss of p21WAF1 through siRNA transfection also reversed the inhibitory effect of rosiglitazone on PASMC proliferation triggered by serotonin. Taken together, our findings suggest that activation of PPAR, induces HO-1 expression, and that this in turn stimulates p21WAF1 expression to suppress PASMC proliferation. Our study also indicates that rosiglitazone, a medicine widely used in the treatment of type 2 diabetes mellitus, has potential benefits for patients with pulmonary hypertension. [source] Down-regulation of heme oxygenase-2 is associated with the increased expression of heme oxygenase-1 in human cell linesFEBS JOURNAL, Issue 23 2006Yuanying Ding Intracellular heme concentrations are maintained in part by heme degradation, which is catalyzed by heme oxygenase. Heme oxygenase consists of two structurally related isozymes, HO-1 and HO-2. Recent studies have identified HO-2 as a potential oxygen sensor. To gain further insights into the regulatory role of HO-2 in heme homeostasis, we analyzed the expression profiles of HO-2 and the biochemical consequences of HO-2 knockdown with specific short interfering RNA (siRNA) in human cells. Both HO-2 mRNA and protein are expressed in the eight human cancer cell lines examined, and HO-1 expression is detectable in five of the cell lines, including HeLa cervical cancer and HepG2 hepatoma. Down-regulation of HO-2 expression with siRNA against HO-2 (siHO-2) caused induction of HO-1 expression at both mRNA and protein levels in HeLa and HepG2 cells. In contrast, knockdown of HO-1 expression did not noticeably influence HO-2 expression. HO-2 knockdown prolonged the half-life of HO-1 mRNA twofold in HeLa cells. Transient transfection assays in HeLa cells revealed that the 4.5-kb human HO-1 gene promoter was activated with selective knockdown of HO-2 in a sequence-dependent manner. Moreover, HO-2 knockdown caused heme accumulation in HeLa and HepG2 cells only when exposed to exogenous hemin. HO-2 knockdown may mimic a certain physiological change that is important in the maintenance of cellular heme homeostasis. These results suggest that HO-2 may down-regulate the expression of HO-1, thereby directing the co-ordinated expression of HO-1 and HO-2. [source] The therapeutic benefits of heme oxygenase (HO-1) inhibition in the management of systemic malignancies besides hepatocellular carcinomasINTERNATIONAL JOURNAL OF CANCER, Issue 3 2009Shailendra Kapoor No abstract is available for this article. [source] Curcumin-induced fibroblast apoptosis and in vitro wound contraction are regulated by antioxidants and heme oxygenase: implications for scar formationJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2009A. Scharstuhl Abstract Fibroblast apoptosis plays a crucial role in normal and pathological scar formation and therefore we studied whether the putative apoptosis-inducing factor curcumin affects fibroblast apoptosis and may function as a novel therapeutic. We show that 25-,M curcumin causes fibroblast apoptosis and that this could be inhibited by co-administration of antioxidants N -acetyl- l -cysteine (NAC), biliverdin or bilirubin, suggesting that reactive oxygen species (ROS) are involved. This is supported by our observation that 25-,M curcumin caused the generation of ROS, which could be completely blocked by addition of NAC or bilirubin. Since biliverdin and bilirubin are downstream products of heme degradation by heme oxygenase (HO), it has been suggested that HO-activity protects against curcumin-induced apoptosis. Interestingly, exposure to curcumin maximally induced HO-1 protein and HO-activity at 10,15 ,M, whereas, at a concentration of >20-,M curcumin HO-1-expression and HO-activity was negligible. NAC-mediated inhibition of 25-,M curcumin-induced apoptosis was demonstrated to act in part via restored HO-1-induction, since the rescuing effect of NAC could be reduced by inhibiting HO-activity. Moreover pre-induction of HO-1 using 5-,M curcumin protected fibroblasts against 25-,M curcumin-induced apoptosis. On a functional level, fibroblast-mediated collagen gel contraction, an in vitro wound contraction model, was completely prevented by 25-,M curcumin, while this could be reversed by co-incubation with NAC, an effect that was also partially HO-mediated. In conclusion, curcumin treatment in high doses (>25 ,M) may provide a novel way to modulate pathological scar formation through the induction of fibroblast apoptosis, while antioxidants, HO-activity and its effector molecules act as a possible fine-tuning regulator. [source] Improved myocardial perfusion in chronic diabetic mice by the up-regulation of pLKB1 and AMPK signalingJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2010Claudia Kusmic Abstract Previous studies related impaired myocardial microcirculation in diabetes to oxidative stress and endothelial dysfunction. Thus, this study was aimed to determine the effect of up-regulating pAMPK-pAKT signaling on coronary microvascular reactivity in the isolated heart of diabetic mice. We measured coronary resistance in wild-type and streptozotocin (STZ)-treated mice, during perfusion pressure changes. Glucose, insulin, and adiponectin levels in plasma and superoxide formation, NOx levels and heme oxygenase (HO) activity in myocardial tissue were determined. In addition, the expression of HO-1, 3-nitrotyrosine, pLKB1, pAMPK, pAKT, and peNOS proteins in control and diabetic hearts were measured. Coronary response to changes in perfusion pressure diverged from control in a time-dependent manner following STZ administration. The responses observed at 28 weeks of diabetes (the maximum time examined) were mimicked by L-NAME administration to control animals and were associated with a decrease in serum adiponectin and myocardial pLKB1, pAMPK, pAKT, and pGSK-3 expression. Cobalt protoporphyrin treatment to induce HO-1 expression reversed the microvascular reactivity seen in diabetes towards that of controls. Up-regulation of HO-1 was associated with an increase in adiponectin, pLKB1, pAKT, pAMPK, pGSK-3, and peNOS levels and a decrease in myocardial superoxide and 3-nitrotyrosine levels. In the present study we describe the time course of microvascular functional changes during the development of diabetes and the existence of a unique relationship between the levels of serum adiponectin, pLKB1, pAKT, and pAMPK activation in diabetic hearts. The restoration of microvascular function suggests a new therapeutic approach to even advanced cardiac microvascular derangement in diabetes. J. Cell. Biochem. 109: 1033,1044, 2010. © 2010 Wiley-Liss, Inc. [source] Plumbagin, a novel Nrf2/ARE activator, protects against cerebral ischemiaJOURNAL OF NEUROCHEMISTRY, Issue 5 2010Tae Gen Son J. Neurochem. (2010) 112, 1316,1326. Abstract Many phytochemicals function as noxious agents that protect plants against insects and other damaging organisms. However, at subtoxic doses, the same phytochemicals may activate adaptive cellular stress response pathways that can protect cells against a variety of adverse conditions. We screened a panel of botanical pesticides using cultured human and rodent neuronal cell models, and identified plumbagin as a novel potent activator of the nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway. In vitro, plumbagin increases nuclear localization and transcriptional activity of Nrf2, and induces the expression of the Nrf2/ARE-dependent genes, such as heme oxygenase 1 in human neuroblastoma cells. Plumbagin specifically activates the Nrf2/ARE pathway in primary mixed cultures from ARE-human placental alkaline phosphatase reporter mice. Exposure of neuroblastoma cells and primary cortical neurons to plumbagin provides protection against subsequent oxidative and metabolic insults. The neuroprotective effects of plumbagin are abolished by RNA interference-mediated knockdown of Nrf2 expression. In vivo, administration of plumbagin significantly reduces the amount of brain damage and ameliorates-associated neurological deficits in a mouse model of focal ischemic stroke. Our findings establish precedence for the identification and characterization of neuroprotective phytochemicals based upon their ability to activate adaptive cellular stress response pathways. [source] Up-regulation of heat shock protein HSP 20 in the hippocampus as an early response to hypoxia of the newbornJOURNAL OF NEUROCHEMISTRY, Issue 2 2006Jean-Claude David Abstract Hypoxia is an important challenge for newborn mammals. Stress generated at the brain level under low oxygenation conditions results in up-regulation of heat shock proteins (HSPs) and other stress proteins. The aim of the present work was to determine the effect of hypoxia in the newborn on some newly described small molecular weight HSPs (HSP 20 and B8) in the hippocampus, cortex and cerebellum of newborn piglets. These effects will be compared with those of other closely related proteins such as ,B crystallin, HSP 27, heme oxygenase (HO)-1, HO-2, cyclooxygenase (COX)-1 and COX-2. The piglets were submitted to hypoxia (5% O2; 95% N2) over either 1 or 4 h, with recovery periods ranging from 0 to 68 h. Western blot analysis showed that HSP 20 was rapidly induced only in the hippocampus, long before hypoxia-inducible transcription factor HIF-1,, while HSP 27 was rapidly induced in the cortex and cerebellum. Vascular epithelial growth factor was increased simultaneously in the three regions. Moreover, an increase in the expression of, respectively, HO-1 and COX-2 was observed later, but at the same time, in the three regions tested. It appears that HSP 20 can be an early marker of hypoxia in the hippocampus. The other small HSPs or stress proteins display different temporal patterns of up-regulation (HSP 27 and HO-1, COX-2) or do not show changes in their expressions (,B crystallin, HSP B8, HO-2 and COX-1). [source] Regulation of intracellular cyclic GMP levels in olfactory sensory neuronsJOURNAL OF NEUROCHEMISTRY, Issue 1 2005Cheil Moon Abstract Cyclic AMP is the primary second messenger mediating odorant signal transduction in mammals. A number of studies indicate that cyclic GMP is also involved in a variety of other olfactory signal transduction processes, including adaptation, neuronal development, and long-term cellular responses in the setting of odorant stimulation. However, the mechanisms that control the production and degradation of cGMP in olfactory sensory neurons (OSNs) remain unclear. Here, we investigate these mechanisms using primary cultures of OSNs. We demonstrate that odorants increase cGMP levels in intact OSNs in vitro. Different from the rapid and transient cAMP responses to odorants, the cGMP elevation is both delayed and sustained. Inhibition of soluble guanylyl cyclase and heme oxygenase blocks these odorant-induced cGMP increases, whereas inhibition of cGMP PDEs (phosphodiesterases) increases this response. cGMP PDE activity is increased by odorant stimulation, and is sensitive to both ambient calcium and cAMP concentrations. Calcium stimulates cGMP PDE activity, whereas cAMP and protein kinase A appears to inhibit it. These data demonstrate a mechanism by which odorant stimulation may regulate cGMP levels through the modulation of cAMP and calcium level in OSNs. Such interactions between odorants and second messenger systems may be important to the integration of immediate and long-term responses in the setting odorant stimulation. [source] Increased Lipopolysaccharide Sensitivity in Alcoholic Fatty Livers Is Independent of Leptin Deficiency and Toll-Like Receptor 4 (TLR4) or TLR2 mRNA ExpressionALCOHOLISM, Issue 6 2005Laszlo Romics Jr Background: Both alcoholic (AFL) and nonalcoholic (NAFL) fatty livers show increased sensitivity to endotoxin-induced injury. Lipopolysaccharide (LPS) is recognized by toll-like receptor 4 (TLR4), whereas lipopeptide triggers TLR2 to induce common downstream activation of nuclear factor (NF)-,B and pro-inflammatory pathways that are activated in AFL and NAFL. Methods: Serum alanine aminotransferase (ALT), tumor necrosis factor (TNF)-,, and interleukin (IL)-6 levels; hepatic NF-,B activity; and expression of TLR2, TLR4, inducible nitric oxide synthase (iNOS), and heme oxygenase (HO)-1 mRNAs were investigated in lean and leptin-deficient ob/ob mice after LPS challenge in combination with acute or chronic alcohol feeding. Results: Increased LPS sensitivity in AFL and NAFL was characterized by elevated serum TNF-, and IL-6 induction. However, there was no difference in TLR2 and TLR4 mRNA levels between lean and ob/ob livers at baseline and after acute or chronic alcohol treatment. LPS increased TLR2, but not TLR4, mRNA levels in all groups. Chronic alcohol feeding and LPS increased serum ALT and TNF-, levels in lean but not in ob/ob mice compared with pair-fed controls. Hepatic NF-,B activation was increased in both ob/ob and lean mice after chronic alcohol feeding compared with pair-fed controls. Expression of iNOS, an inducer of oxidative stress, and HO-1, a cytoprotective protein, were higher in ob/ob compared with lean mice after chronic alcohol feeding. However, LPS-induced HO-1, but not iNOS, expression was attenuated in ob/ob compared with lean mice. Conclusion: These results imply that the increased sensitivity of AFL to LPS occurs without up-regulation of TLR2 or TLR4 genes and may be related to an imbalance of pro-inflammatory/oxidative and cytoprotective mechanisms. [source] Carbon Monoxide has Antioxidative Properties in the Liver Involving p38 MAP Kinase Pathway in a Murine Model of Systemic InflammationMICROCIRCULATION, Issue 7 2010JÜRGEN BRUGGER Please cite this paper as: Brugger, Schick, Brock, Baumann, Muellenbach, Roewer and Wunder (2010). Carbon Monoxide has Antioxidative Properties in the Liver Involving p38 MAP Kinase Pathway in a Murine Model of Systemic Inflammation. Microcirculation17(7), 504,513. Abstract Objective:, Reactive oxygen species (ROS) are important in the hepatocellular injury process during a systemic inflammation. We examined the role of carbon monoxide (CO) on the hepatic generation of ROS with in-vivo and in-vitro models of systemic inflammation. Methods:, Using a murine model of bilateral hindlimb ischemia-reperfusion (I/R) we examined the effect of CO treatment on hepatic ROS formation, oxidative status, and cell injury. Cultured HUVEC were used to investigate intracellular pathways. Results:, CO treatment reduced hepatic lipid peroxidation, re-established total hepatic glutathione and glutathione disulfide (GSH/GSSG) levels and reduced hepatocellular injury. Inhibition of heme oxygenase (HO) during treatment with CO during hindlimb I/R failed to alter the antioxidant qualities provided by CO. The production of ROS after tumor necrosis factor-, (TNF-,) stimulation in HUVEC was diminished after exposure to CO. Treatment with CO during HO inhibition reduced both ROS formation and cell injury. Inhibiting the p38 MAPK (mitogen-activated protein kinase) pathway with pyridinyl imidazol (SB203580) revealed that the antioxidant potential of CO involved the activation of p38 MAPK. Conclusions:, CO has direct antioxidant potential independently of any HO activity during systemic inflammation. The antioxidant effects afforded by CO involve the activation of the p38 MAPK pathway. [source] Antioxidant and Vasodilatory Effects of Heme Oxygenase on Mesenteric Vasoreactivity Following Chronic HypoxiaMICROCIRCULATION, Issue 2 2009KAREN SWEAZEA ABSTRACT Objective: Chronic hypoxia (CH) results in impaired vasoconstriction associated with increased expression of heme oxygenase (HO). We hypothesized that enhanced HO activity minimizes reactive oxygen species (ROS) in arteries from CH rats, thereby normalizing endothelium-dependent vasodilation and concurrently produces carbon monoxide (CO), resulting in tonic vasodilation. Methods: ROS were quantified in mesenteric arteries from control and CH Sprague-Dawley rats. Reactivity to the endothelium-dependent vasodilator, acetylcholine (ACh), and the vasoconstrictor, phenylephrine (PE), were also assessed. Results: Basal ROS levels did not differ between groups and were similarly increased by HO inhibition. In contrast, catalase inhibition increased ROS in CH rats only. Vasodilatory responses to ACh were not different between groups. Combined inhibition of catalase and HO impaired PE-induced vasoconstriction in both groups. CH-induced impairment of vasoconstriction was reversed by either catalase or HO inhibition supporting the protective roles of the HO and catalase pathways following CH. Increased vascular smooth muscle calcium was observed with inhibition in the CH group, suggesting that catalase and HO-derived CO elicit reduced calcium influx, leading to the impaired vasoconstriction. Conclusions: Our data suggest that although the HO pathway is an important antioxidant influence, impaired vasoconstriction following CH appears to be due to effects of ROS and HO-derived CO. [source] Role of Vascular Heme Oxygenase in Reduced Myogenic Reactivity Following Chronic HypoxiaMICROCIRCULATION, Issue 2 2006JAY S. NAIK ABSTRACT Objective: Exposure to chronic hypoxia (CH) results in a persistent endothelium-dependent vascular smooth muscle hyperpolarization that diminishes vasoconstrictor reactivity. Experiments were performed to test the hypothesis that products of both cytochrome P450 epoxygenase (CYP) and heme oxygenase (HO) are required for the persistent diminished myogenic reactivity following CH. Methods: The authors examined myogenic responses of mesenteric arteries isolated from control and CH (48 h; PB = 380 mmHg) rats in the presence of a HO inhibitor (zinc protoporphyrin IX; ZnPPIX) or combined HO and CYP epoxygenase inhibition (sulfaphenazole). Arteries were isolated and cannulated and the vascular smooth muscle was loaded with the Ca2 + indicator Fura-2. Results: Control vessels maintained their internal diameter in response to step increases in intraluminal pressure, whereas arteries from CH animals passively distended. ZnPPIX augmented myogenic reactivity and [Ca2 +] in arteries from CH animals. Combined administration of sulfaphenazole and ZnPPIX did not have an additional effect compared to ZnPPIX alone. Myogenic reactivity in control vessels was not altered by ZnPPIX or ZnPPIX + sulfaphenazole. Conclusions: HO appears to play a role in regulating myogenic reactivity following CH. Furthermore, these data suggest that products of HO and CYP are both required for the observed attenuation in vasoreactivity following CH. [source] Protective Effects of Ischemic Preconditioning on the Intestinal Mucosal Microcirculation Following Ischemia,Reperfusion of the IntestineMICROCIRCULATION, Issue 8 2005ISMAIL H. MALLICK ABSTRACT Objective: The small bowel villi are extremely sensitive to ischemia,reperfusion (IR) injury and a range of microcirculatory disturbances contribute to structural and functional changes. The aim of this study was to determine the protective effects of ischemic preconditioning (IPC) of the intestine on the mucosal villous microcirculation during IR injury of the intestine and whether heme oxygenase (HO) is involved in the protection. Methods: Rats were allocated into 4 groups: (1) sham, (2) IR consisting of 30 min of ischemia followed by 2 h of reperfusion, (3) IPC, as in IR group, but preceded by 10 min of ischemia and 10 min of reperfusion, and (4) with administration of zinc protoporphyrin, an HO inhibitor before IPC and IR. The mucosa of an exteriorized segment of ileum was visualized. Mucosal perfusion index (MPI), red blood cell (RBC) velocity and leukocyte,endothelial interactions during reperfusion were assessed continuously using in vivo fluorescence microscopy. HO activity in the ileum was assessed at the end of the reperfusion period. Results: IPC improved the MPI by 26% and the RBC velocity by 29% on comparison to IR. IR led to a 52% increase in leukocyte,endothelial interactions on comparison to IPC. The administration of zinc protoporphyrin reversed the beneficial effects of IPC. There was a two fold increase of HO activity in IPC compared to IR, whereas zinc protoporphyrin significantly reduced the HO activity. Conclusions: IPC conferred a protective effect on the villous microcirculation possibly via HO and might prove to be an effective strategy for the amelioration of IR injury. [source] Remote Liver Injury is Attenuated by Adenovirus-Mediated Gene Transfer of Heme Oxygenase-1 During the Systemic Inflammatory Response SyndromeMICROCIRCULATION, Issue 7 2004SARAH D. MCCARTER ABSTRACT Objectives: Adenovirus-mediated gene therapy is being investigated with increasing success for future treatment of autoimmune diseases. However, the use of adenoviruses is still limited by inflammatory and immune responses in the target organ. Previous work by the authors' laboratory established that the adenovirus encoding inducible heme oxygenase (Ad-HO-1) does not elicit the acute hepatic inflammation normally caused by adenoviruses, inviting further investigation in models of severe inflammation. Concurrently, there is increasing evidence for an endogenous protective role for heme oxygenase (HO) in the liver during the systemic inflammatory response syndrome (SIRS). Building on our previous results, this study investigated the effect of Ad-HO-1 pretreatment on remote liver injury during normotensive SIRS, induced by bilateral hind limb ischemia and reperfusion. Methods: Microvascular perfusion and hepatocyte death were quantified using established intravital videomicroscopy techniques. Hepatocellular injury and liver function were assessed using blood-borne indicators. Results: Microvascular perfusion deficits and increased hepatocyte death occurred following limb ischemia and 3 h of reperfusion in vehicle-pretreated animals; however, Ad-HO-1 pretreatment prevented these deficits. In contrast, the increase in serum alanine transaminase levels was unaffected by Ad-HO-1 pretreatment. Serum bilirubin levels were increased during systemic inflammation, predominantly in the conjugated form; and, this increase was prevented by administration of Ad-HO-1. Conclusions: These data indicate that gene transfer of inducible HO is an effective method to protect the liver during SIRS, providing incentive for further investigation into gene therapy strategies exploiting this anti-inflammatory enzyme. [source] Nrf2-mediated induction of detoxifying enzymes by alantolactone present in Inula heleniumPHYTOTHERAPY RESEARCH, Issue 11 2008Ji Yeon Seo Abstract Our previous study showed that a methanol extract of Inula helenium had the potential to induce detoxifying enzymes such as quinone reductase (QR) and glutathione S -transferase (GST) activity. In this study the methanol extract was further fractionated using silica gel chromatography and vacuum liquid chromatography, to yield pure compounds alantolactone and isoalantolactone as QR inducers. Alantolactone caused a dose-dependent induction of antioxidant enzymes including QR, GST, , -glutamylcysteine synthase, glutathione reductase, and heme oxygenase 1 in hepa1c1c7 mouse hepatoma cells. The compound increased the luciferase activity of HepG2-C8 cells, transfectants carrying antioxidant response element (ARE)-luciferase gene, in a dose-dependent manner, suggesting ARE-mediated transcriptional activation of antioxidant enzymes. Alantolactone also stimulated the nuclear accumulation of Nrf2 that was inhibited by phosphatidylinositol 3-kinase (PI3K) inhibitors. In conclusion, alantolactone appears to induce detoxifying enzymes via activation of PI3K and JNK signaling pathways, leading to translocation of Nrf2, and subsequent interaction between Nrf2 and ARE in the encoding genes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Putative Role of Carbon Monoxide Signaling Pathway in Penile Erectile FunctionTHE JOURNAL OF SEXUAL MEDICINE, Issue 1 2009Mohamed T. Abdel Aziz MD ABSTRACT Introduction., Erectile response depends on nitric oxide (NO) generated by NO synthase (NOS) enzyme of the nerves and vascular endothelium in the cavernous tissue. NO activates soluble guanylate cyclase (sGC), leading to the production of cyclic guanosine monophosphate (cGMP). cGMP activates cGMP-dependent protein kinase that activates Ca2+/ATPase pump that activates Ca2+/K efflux pump extruding Ca2+ across the plasma membrane with consequent smooth muscle cell relaxation. A role similar to that of NOS/NO signaling has been postulated for carbon monoxide (CO) produced in mammals from heme catabolism by heme oxygenase (HO) enzyme. Aim., To assess CO signaling pathway for erectile function by reviewing published studies. Methods., A systematic review of published studies on this affair based on Pubmed and Medical Subject Heading databases, with search for all concerned articles. Main Outcome Measures., Documentation of positive as well as negative criteria of CO/HO signaling focused on penile tissue. Results., The concept that HO-derived CO could play a role in mediating erectile function acting in synergism with, or as a potentiator for, NOS/NO signaling pathway is gaining momentum. CO/HO signaling pathway has been shown to partially mediate the actions of oral phosphodiesterase type 5 inhibitors. In addition, it was shown that the use of CO releasing molecules potentiated cavernous cGMP levels. However, increased CO production or release was reported to be associated, in some studies, with vasoconstriction. Conclusion., This review sheds a light on the significance of cavernous tissue CO signaling pathway that may pave the way for creation of therapeutic modalities based on this pathway. Abdel Aziz MT, Mostafa T, Atta H, Wassef MA, Fouad HH, Rashed LA, and Sabry D. Putative role of carbon monoxide signaling pathway in penile erectile function. J Sex Med 2009;6:49,60. [source] Expression and Activity of Heme Oxygenase-1 in Artificially Induced Low-Flow Priapism in Rat Penile TissuesTHE JOURNAL OF SEXUAL MEDICINE, Issue 8 2008Yong Chun Jin ABSTRACT Introduction., The inducible isoform of heme oxygenase (HO)-1 regulates the vascular smooth muscle tone and responds to hypoxia. Aim., To investigate the role of HO-1 in a low-flow priapism. Materials and Methods., Sixty male Sprague-Dawley rats were divided into five groups of six rats each. Each group of rats was sacrificed at 0 hour (group 1, control), 4 hours (group 2), 8 hours (group 3), 12 hours (group 4), and 24 hours (group 5) after inducing an artificial veno-occlusive priapism. The changes of the expression and activity of HO-1, and the expression of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS), and levels of cyclic guanosine monophosphate in the penis were examined in a low-flow priapism. In addition, the HO-1 expression level in the aortas from each group was simultaneously measured to determine whether the changes in HO-1 were systemic. Main Outcome Measures., The expression and activity of HO-1 was examined in artificially induced veno-occlusive priapism in rat penile tissues. Results., The expression of the HO-1 protein and the HO-1 enzyme activities in the penile tissues were gradually increased as time increased from 0 to 24 hours (P < 0.01). HO-1 immunoreactivities were localized in the endothelial layer of the cavernosal sinusoids. The expression of iNOS were also increased at 12 and 24 hours. The cyclic guanosine monophosphate level was also significantly increased at 24 hours (P < 0.05). However, the expression of the eNOS protein showed no statistically significant change with time, and the expression of the HO-1 protein in the aorta also showed no significant change with time. Conclusions., A higher induction of HO-1 with time was observed in artificially induced veno-occlusive priapism, which might play a protective role against hypoxic injury. However, this may also play an important role in the vicious circle observed in a low-flow priapism. Jin YC, Gam SC, Jung JH, Hyun JS, Chang KC, and Hyun JS. Expression and activity of heme oxygenase-1 in artificially induced low-flow priapism in rat penile tissues. J Sex Med 2008;5:1876,1882. [source] Concurrent interactions of heme and FLU with Glu tRNA reductase (HEMA1), the target of metabolic feedback inhibition of tetrapyrrole biosynthesis, in dark- and light-grown Arabidopsis plantsTHE PLANT JOURNAL, Issue 6 2004David Goslings Summary The regulation of tetrapyrrole biosynthesis in higher plants has been attributed to metabolic feedback inhibition of Glu tRNA reductase by heme. Recently, another negative regulator of tetrapyrrole biosynthesis has been discovered, the FLU protein. During an extensive second site screen of mutagenized flu seedlings a suppressor of flu, ulf3, was identified that is allelic to hy1 and encodes a heme oxygenase. Increased levels of heme in the hy1 mutant have been implicated with inhibiting Glu tRNA reductase and suppressing the synthesis of , -aminolevulinic acid (ALA) and Pchlide accumulation. When combined with hy1 or ulf3 upregulation of ALA synthesis and overaccumulation of protochlorophyllide in the flu mutants were severely suppressed supporting the notion that heme antagonizes the effect of the flu mutation by inhibiting Glu tRNA reductase independently of FLU. The coiled-coil domain at the C-terminal end of Glu tRNA reductase interacts with FLU, whereas the N-terminal site of Glu tRNA reductase that is necessary for the inhibition of the enzyme by heme is not required for this interaction. The interaction with FLU is specific for the Glu tRNA reductase encoded by HEMA1 that is expressed in photosynthetically active tissues. FLU seems to be part of a second regulatory circuit that controls chlorophyll biosynthesis by interacting directly with Glu tRNA reductase not only in etiolated seedlings but also in light-adapted green plants. [source] Phytochromes confer the photoperiodic control of flowering in rice (a short-day plant)THE PLANT JOURNAL, Issue 5 2000Takeshi Izawa Summary The photoperiodic sensitivity 5 (se5) mutant of rice, a short-day plant, has a very early flowering phenotype and is completely deficient in photoperiodic response. We have cloned the SE5 gene by candidate cloning and demonstrated that it encodes a putative heme oxygenase. Lack of responses of coleoptile elongation by light pulses and photoreversible phytochromes in crude extracts of se5 indicate that SE5 may function in phytochrome chromophore biosynthesis. Ectopic expression of SE5 cDNA by the CaMV 35S promoter restored the photoperiodic response in the se5 mutant. Our results indicate that phytochromes confer the photoperiodic control of flowering in rice. Comparison of se5 with hy1, a counterpart mutant of Arabidopsis, suggests distinct roles of phytochromes in the photoperiodic control of flowering in these two species. [source] Heme oxygenase enzyme activity in seminal plasma of oligoasthenoteratozoospermic males with varicoceleANDROLOGIA, Issue 4 2010M. T. Abdel Aziz Summary This work aimed to assess seminal plasma heme oxygenase (HO) enzyme activity in oligoasthenoteratozoospermia (OAT) males with varicocele. Ninety-three men were divided according to their sperm count and clinical examination into: healthy fertile controls (n = 34), OAT without varicocele (n = 37) and OAT associated with varicocele (n = 22). They were subjected to semen analysis and estimation of seminal plasma HO enzyme activity in the form of bilirubin concentration. Seminal plasma HO enzyme activity decreased significantly in OAT cases compared with controls. Seminal plasma HO in OAT cases associated with varicocele decreased significantly compared with OAT cases without varicocele and healthy controls (mean ± SD; 109.2 ± 29.5, 283.6 ± 88.4, 669.5 ± 236.1 nMol bilirubin/mg ptn/min, P < 0.001). There was positive correlation between seminal plasma HO enzyme activity and sperm concentration, per cent of motile spermatozoa, number of motile spermatozoas ml,1 and significant negative correlation with sperm abnormal forms per cent. It is concluded that varicocele has a negative impact on seminal HO enzyme activity. Therefore, improved seminal picture after correcting varicocele repair might be related, in part, to improved HO action(s). [source] Cilostazol enhances apoptosis of synovial cells from rheumatoid arthritis patients with inhibition of cytokine formation via Nrf2-linked heme oxygenase 1 inductionARTHRITIS & RHEUMATISM, Issue 3 2010So Youn Park Objective To assess the effects of cilostazol in inhibiting proliferation and enhancing apoptosis in synovial cells from patients with rheumatoid arthritis (RA). Methods Synovial cell proliferation was measured by MTT assay. The expression of NF-,B, I,B,, Bcl-2, Bax, heme oxygenase 1 (HO-1), and Nrf2 was determined by Western blotting. Results Cilostazol suppressed synovial cell proliferation by arresting the G2/M phases of the cell cycle, and this was reversed by KT5720, an inhibitor of protein kinase A. Cilostazol increased the number of TUNEL-positive cells, with increased cytochrome c release and apoptosis-inducing factor translocation as well as increased caspase 3 activation. Cilostazol (10 ,M) and cobalt protoporphyrin IX (CoPP) increased HO-1 messenger RNA and protein expression. These effects were suppressed by zinc protoporphyrin IX (ZnPP), an HO-1 inhibitor. Cilostazol and CoPP significantly increased I,B, in the cytosol and decreased NF-,B p65 expression in the nucleus. Increased expression of tumor necrosis factor , (TNF,), interleukin-1, (IL-1,), and IL-6 induced by lipopolysaccharide was attenuated by cilostazol and CoPP, and this was reversed by ZnPP. In mice with collagen-induced arthritis treated with cilostazol (10 and 30 mg/kg/day), paw thickness was decreased with increased apoptotic cells in the joints. In synovial cells transfected with small interfering RNA (siRNA) targeting HO-1, cilostazol did not suppress expression of TNF,, IL-1,, and IL-6, in contrast to findings with negative control cells. Cilostazol- and CoPP-induced HO-1 expression was diminished in cells transfected with Nrf2 siRNA. Conclusion Cilostazol suppressed proliferation of synovial cells from RA patients by enhancing apoptosis, and also inhibited cytokine production via mediation of cAMP-dependent protein kinase activation,coupled Nrf2-linked HO-1 expression. [source] | ||||||||||||||||