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Fahrer J, Wittmann S, Wolf AC, Kostka T. Heme Oxygenase-1 and Its Role in Colorectal Cancer. Antioxidants (Basel) 2023; 12:1989. [PMID: 38001842 PMCID: PMC10669411 DOI: 10.3390/antiox12111989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
Heme oxygenase-1 (HO-1) is an enzyme located at the endoplasmic reticulum, which is responsible for the degradation of cellular heme into ferrous iron, carbon monoxide and biliverdin-IXa. In addition to this main function, the enzyme is involved in many other homeostatic, toxic and cancer-related mechanisms. In this review, we first summarize the importance of HO-1 in physiology and pathophysiology with a focus on the digestive system. We then detail its structure and function, followed by a section on the regulatory mechanisms that control HO-1 expression and activity. Moreover, HO-2 as important further HO isoform is discussed, highlighting the similarities and differences with regard to HO-1. Subsequently, we describe the direct and indirect cytoprotective functions of HO-1 and its breakdown products carbon monoxide and biliverdin-IXa, but also highlight possible pro-inflammatory effects. Finally, we address the role of HO-1 in cancer with a particular focus on colorectal cancer. Here, relevant pathways and mechanisms are presented, through which HO-1 impacts tumor induction and tumor progression. These include oxidative stress and DNA damage, ferroptosis, cell cycle progression and apoptosis as well as migration, proliferation, and epithelial-mesenchymal transition.
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Affiliation(s)
- Jörg Fahrer
- Division of Food Chemistry and Toxicology, Department of Chemistry, RPTU Kaiserslautern-Landau, Erwin-Schrödinger Strasse 52, D-67663 Kaiserslautern, Germany; (S.W.); (A.-C.W.)
| | | | | | - Tina Kostka
- Division of Food Chemistry and Toxicology, Department of Chemistry, RPTU Kaiserslautern-Landau, Erwin-Schrödinger Strasse 52, D-67663 Kaiserslautern, Germany; (S.W.); (A.-C.W.)
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Leal EC, Carvalho E. Heme Oxygenase-1 as Therapeutic Target for Diabetic Foot Ulcers. Int J Mol Sci 2022; 23:ijms231912043. [PMID: 36233341 PMCID: PMC9569859 DOI: 10.3390/ijms231912043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/04/2022] [Accepted: 10/09/2022] [Indexed: 11/22/2022] Open
Abstract
A diabetic foot ulcer (DFU) is one of the major complications of diabetes. Wound healing under diabetic conditions is often impaired. This is in part due to the excessive oxidative stress, prolonged inflammation, immune cell dysfunction, delayed re-epithelialization, and decreased angiogenesis present at the wound site. As a result of these multifactorial impaired healing pathways, it has been difficult to develop effective therapeutic strategies for DFU. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme in heme degradation generating carbon monoxide (CO), biliverdin (BV) which is converted into bilirubin (BR), and iron. HO-1 is a potent antioxidant. It can act as an anti-inflammatory, proliferative, angiogenic and cytoprotective enzyme. Due to its biological functions, HO-1 plays a very important role in wound healing, in part mediated through the biologically active end products generated by its enzymatic activity, particularly CO, BV, and BR. Therapeutic strategies involving the activation of HO-1, or the topical application of its biologically active end products are important in diabetic wound healing. Therefore, HO-1 is an attractive therapeutic target for DFU treatment. This review will provide an overview and discussion of the importance of HO-1 as a therapeutic target for diabetic wound healing.
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Affiliation(s)
- Ermelindo Carreira Leal
- Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
- Institute of Interdisciplinary Research, University of Coimbra, 3004-504 Coimbra, Portugal
- Correspondence: (E.C.L.); (E.C.); Tel.: +351-239-820-190 (E.C.L. & E.C.)
| | - Eugenia Carvalho
- Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
- Institute of Interdisciplinary Research, University of Coimbra, 3004-504 Coimbra, Portugal
- Correspondence: (E.C.L.); (E.C.); Tel.: +351-239-820-190 (E.C.L. & E.C.)
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Nitti M, Ivaldo C, Traverso N, Furfaro AL. Clinical Significance of Heme Oxygenase 1 in Tumor Progression. Antioxidants (Basel) 2021; 10:antiox10050789. [PMID: 34067625 PMCID: PMC8155918 DOI: 10.3390/antiox10050789] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/30/2021] [Accepted: 05/10/2021] [Indexed: 02/07/2023] Open
Abstract
Heme oxygenase 1 (HO-1) plays a key role in cell adaptation to stressors through the antioxidant, antiapoptotic, and anti-inflammatory properties of its metabolic products. For these reasons, in cancer cells, HO-1 can favor aggressiveness and resistance to therapies, leading to poor prognosis/outcome. Genetic polymorphisms of HO-1 promoter have been associated with an increased risk of cancer progression and a high degree of therapy failure. Moreover, evidence from cancer biopsies highlights the possible correlation between HO-1 expression, pathological features, and clinical outcome. Indeed, high levels of HO-1 in tumor specimens often correlate with reduced survival rates. Furthermore, HO-1 modulation has been proposed in order to improve the efficacy of antitumor therapies. However, contrasting evidence on the role of HO-1 in tumor biology has been reported. This review focuses on the role of HO-1 as a promising biomarker of cancer progression; understanding the correlation between HO-1 and clinical data might guide the therapeutic choice and improve the outcome of patients in terms of prognosis and life quality.
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Heteromeric complex formation between human cytochrome P450 CYP1A1 and heme oxygenase-1. Biochem J 2021; 478:377-388. [PMID: 33394027 DOI: 10.1042/bcj20200768] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/15/2020] [Accepted: 01/04/2021] [Indexed: 01/10/2023]
Abstract
P450 and heme oxygenase-1 (HO-1) receive their necessary electrons by interaction with the NADPH-cytochrome P450 reductase (POR). As the POR concentration is limiting when compared with P450 and HO-1, they must effectively compete for POR to function. In addition to these functionally required protein-protein interactions, HO-1 forms homomeric complexes, and several P450s have been shown to form complexes with themselves and with other P450s, raising the question, 'How are the HO-1 and P450 systems organized in the endoplasmic reticulum?' Recently, CYP1A2 was shown to associate with HO-1 affecting the function of both proteins. The goal of this study was to determine if CYP1A1 formed complexes with HO-1 in a similar manner. Complex formation among POR, HO-1, and CYP1A1 was measured using bioluminescence resonance energy transfer, with results showing HO-1 and CYP1A1 form a stable complex that was further stabilized in the presence of POR. The POR•CYP1A1 complex was readily disrupted by the addition of HO-1. CYP1A1 also was able to affect the POR•HO-1 complex, although the effect was smaller. This interaction between CYP1A1 and HO-1 also affected function, where the presence of CYP1A1 inhibited HO-1-mediated bilirubin formation by increasing the KmPOR•HO-1 without affecting the Vmaxapp. In like manner, HO-1 inhibited CYP1A1-mediated 7-ethoxyresorufin dealkylation by increasing the KmPOR•CYP1A1. Based on the mathematical simulation, the results could not be explained by a model where CYP1A1 and HO-1 simply compete for POR, and are consistent with the formation of a stable CYP1A1•HO-1 complex that affected the functional characteristics of both moieties.
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Connick JP, Reed JR, Cawley GF, Backes WL. Heme oxygenase-1 affects cytochrome P450 function through the formation of heteromeric complexes: Interactions between CYP1A2 and heme oxygenase-1. J Biol Chem 2021; 296:100030. [PMID: 33148696 PMCID: PMC7948974 DOI: 10.1074/jbc.ra120.015911] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/27/2020] [Accepted: 11/04/2020] [Indexed: 12/16/2022] Open
Abstract
Heme oxygenase 1 (HO-1) and the cytochromes P450 (P450s) are endoplasmic reticulum-bound enzymes that rely on the same protein, NADPH-cytochrome P450 reductase (POR), to provide the electrons necessary for substrate metabolism. Although the HO-1 and P450 systems are interconnected owing to their common electron donor, they generally have been studied separately. As the expressions of both HO-1 and P450s are affected by xenobiotic exposure, changes in HO-1 expression can potentially affect P450 function and, conversely, changes in P450 expression can influence HO-1. The goal of this study was to examine interactions between the P450 and HO-1 systems. Using bioluminescence resonance energy transfer (BRET), HO-1 formed HO-1•P450 complexes with CYP1A2, CYP1A1, and CYP2D6, but not all P450s. Studies then focused on the HO-1-CYP1A2 interaction. CYP1A2 formed a physical complex with HO-1 that was stable in the presence of POR. As expected, both HO-1 and CYP1A2 formed BRET-detectable complexes with POR. The POR•CYP1A2 complex was readily disrupted by the addition of HO-1, whereas the POR•HO-1 complex was not significantly affected by the addition of CYP1A2. Interestingly, enzyme activities did not follow this pattern. BRET data suggested substantial inhibition of CYP1A2-mediated 7-ethoxyresorufin de-ethylation in the presence of HO-1, whereas its activity was actually stimulated at subsaturating POR. In contrast, HO-1-mediated heme metabolism was inhibited at subsaturating POR. These results indicate that HO-1 and CYP1A2 form a stable complex and have mutual effects on the catalytic behavior of both proteins that cannot be explained by a simple competition for POR.
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Affiliation(s)
- J Patrick Connick
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - James R Reed
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - George F Cawley
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Wayne L Backes
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.
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Targeting Heme Oxygenase-1 in the Arterial Response to Injury and Disease. Antioxidants (Basel) 2020; 9:antiox9090829. [PMID: 32899732 PMCID: PMC7554957 DOI: 10.3390/antiox9090829] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 08/31/2020] [Accepted: 09/03/2020] [Indexed: 02/06/2023] Open
Abstract
Heme oxygenase-1 (HO-1) catalyzes the degradation of heme into carbon monoxide (CO), iron, and biliverdin, which is rapidly metabolized to bilirubin. The activation of vascular smooth muscle cells (SMCs) plays a critical role in mediating the aberrant arterial response to injury and a number of vascular diseases. Pharmacological induction or gene transfer of HO-1 improves arterial remodeling in animal models of post-angioplasty restenosis, vascular access failure, atherosclerosis, transplant arteriosclerosis, vein grafting, and pulmonary arterial hypertension, whereas genetic loss of HO-1 exacerbates the remodeling response. The vasoprotection evoked by HO-1 is largely ascribed to the generation of CO and/or the bile pigments, biliverdin and bilirubin, which exert potent antioxidant and anti-inflammatory effects. In addition, these molecules inhibit vascular SMC proliferation, migration, apoptosis, and phenotypic switching. Several therapeutic strategies are currently being pursued that may allow for the targeting of HO-1 in arterial remodeling in various pathologies, including the use of gene delivery approaches, the development of novel inducers of the enzyme, and the administration of unique formulations of CO and bilirubin.
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Sugishima M, Wada K, Fukuyama K. Recent Advances in the Understanding of the Reaction Chemistries of the Heme Catabolizing Enzymes HO and BVR Based on High Resolution Protein Structures. Curr Med Chem 2020; 27:3499-3518. [PMID: 30556496 PMCID: PMC7509768 DOI: 10.2174/0929867326666181217142715] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/21/2018] [Accepted: 12/11/2018] [Indexed: 01/15/2023]
Abstract
In mammals, catabolism of the heme group is indispensable for life. Heme is first cleaved by the enzyme Heme Oxygenase (HO) to the linear tetrapyrrole Biliverdin IXα (BV), and BV is then converted into bilirubin by Biliverdin Reductase (BVR). HO utilizes three Oxygen molecules (O2) and seven electrons supplied by NADPH-cytochrome P450 oxidoreductase (CPR) to open the heme ring and BVR reduces BV through the use of NAD(P)H. Structural studies of HOs, including substrate-bound, reaction intermediate-bound, and several specific inhibitor-bound forms, reveal details explaining substrate binding to HO and mechanisms underlying-specific HO reaction progression. Cryo-trapped structures and a time-resolved spectroscopic study examining photolysis of the bond between the distal ligand and heme iron demonstrate how CO, produced during the HO reaction, dissociates from the reaction site with a corresponding conformational change in HO. The complex structure containing HO and CPR provides details of how electrons are transferred to the heme-HO complex. Although the tertiary structure of BVR and its complex with NAD+ was determined more than 10 years ago, the catalytic residues and the reaction mechanism of BVR remain unknown. A recent crystallographic study examining cyanobacterial BVR in complex with NADP+ and substrate BV provided some clarification regarding these issues. Two BV molecules are bound to BVR in a stacked manner, and one BV may assist in the reductive catalysis of the other BV. In this review, recent advances illustrated by biochemical, spectroscopic, and crystallographic studies detailing the chemistry underlying the molecular mechanism of HO and BVR reactions are presented.
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Affiliation(s)
- Masakazu Sugishima
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Japan
| | - Kei Wada
- Department of Medical Sciences, University of Miyazaki, Miyazaki, Japan
| | - Keiichi Fukuyama
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan.,Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Japan
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Kochert BA, Fleischhacker AS, Wales TE, Becker DF, Engen JR, Ragsdale SW. Dynamic and structural differences between heme oxygenase-1 and -2 are due to differences in their C-terminal regions. J Biol Chem 2019; 294:8259-8272. [PMID: 30944174 DOI: 10.1074/jbc.ra119.008592] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/02/2019] [Indexed: 11/06/2022] Open
Abstract
Heme oxygenase (HO) catalyzes heme degradation, a process crucial for regulating cellular levels of this vital, but cytotoxic, cofactor. Two HO isoforms, HO1 and HO2, exhibit similar catalytic mechanisms and efficiencies. They also share catalytic core structures, including the heme-binding site. Outside their catalytic cores are two regions unique to HO2: a 20-amino acid-long N-terminal extension and a C-terminal domain containing two heme regulatory motifs (HRMs) that bind heme independently of the core. Both HO isoforms contain a C-terminal hydrophobic membrane anchor; however, their sequences diverge. Here, using hydrogen-deuterium exchange MS, size-exclusion chromatography, and sedimentation velocity, we investigated how these divergent regions impact the dynamics and structure of the apo and heme-bound forms of HO1 and HO2. Our results reveal that heme binding to the catalytic cores of HO1 and HO2 causes similar dynamic and structural changes in regions (proximal, distal, and A6 helices) within and linked to the heme pocket. We observed that full-length HO2 is more dynamic than truncated forms lacking the membrane-anchoring region, despite sharing the same steady-state activity and heme-binding properties. In contrast, the membrane anchor of HO1 did not influence its dynamics. Furthermore, although residues within the HRM domain facilitated HO2 dimerization, neither the HRM region nor the N-terminal extension appeared to affect HO2 dynamics. In summary, our results highlight significant dynamic and structural differences between HO2 and HO1 and indicate that their dissimilar C-terminal regions play a major role in controlling the structural dynamics of these two proteins.
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Affiliation(s)
- Brent A Kochert
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | | | - Thomas E Wales
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Donald F Becker
- Department of Biochemistry, Redox Biology Center, University of Nebraska, Lincoln, Nebraska 68588
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Stephen W Ragsdale
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109.
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Translocation of heme oxygenase-1 contributes to imatinib resistance in chronic myelogenous leukemia. Oncotarget 2017; 8:67406-67421. [PMID: 28978042 PMCID: PMC5620182 DOI: 10.18632/oncotarget.18684] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 05/23/2017] [Indexed: 02/03/2023] Open
Abstract
Heme oxygenase-1 (HO-1) degrades heme to bilirubin. In addition, it is upregulated in malignant disease and has been described as an important factor for cancer prognosis and therapy. Under physiological conditions HO-1 is anchored to the endoplasmic reticulum (ER). Under stress conditions HO-1 can be cleaved and subsequently translocates to the cytosol and nucleus. In this study we systematically investigated the influence of HO-1's catabolic activity and subcellular localization on resistance against the tyrosine kinase inhibitor imatinib in leukemia cells by confocal laser scanning microscopy, hemoglobin synthesis experiments and cell viability assays. We created two types of monoclonal K562 cell lines stably transfected with GFP-tagged HO-1: cell lines expressing ER anchored HO-1 or anchorless HO-1. Since translocation of HO-1 disrupts the association with cytochrome P450 reductase, heme degrading activity was higher for ER anchored versus anchorless HO-1. Cell viability tests with increasing concentrations of imatinib showed IC50-values for all six cell lines with ER localized HO-1 that were similar to control cells. However, out of the seven cell lines with anchorless HO-1, two showed a statistically significant increase in the imatinib IC50 (19.76 μM and 12.35 μM versus 2.35 – 7.57 μM of sensitive cell lines) corresponding to plasma concentrations outside the therapeutic range. We conclude that the presence of translocated HO-1 in the cytosol and nucleus supports imatinib resistance while it is not sufficient to cause imatinib resistance in every cell line. In contrast, an increase in ER anchored HO-1 with high heme degrading activity does not contribute to imatinib resistance.
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Abstract
Heme oxygenases are composed of two isozymes, Hmox1 and Hmox2, that catalyze the degradation of heme to carbon monoxide (CO), ferrous iron, and biliverdin, the latter of which is subsequently converted to bilirubin. While initially considered to be waste products, CO and biliverdin/bilirubin have been shown over the last 20 years to modulate key cellular processes, such as inflammation, cell proliferation, and apoptosis, as well as antioxidant defense. This shift in paradigm has led to the importance of heme oxygenases and their products in cell physiology now being well accepted. The identification of the two human cases thus far of heme oxygenase deficiency and the generation of mice deficient in Hmox1 or Hmox2 have reiterated a role for these enzymes in both normal cell function and disease pathogenesis, especially in the context of cardiovascular disease. This review covers the current knowledge on the function of both Hmox1 and Hmox2 at both a cellular and tissue level in the cardiovascular system. Initially, the roles of heme oxygenases in vascular health and the regulation of processes central to vascular diseases are outlined, followed by an evaluation of the role(s) of Hmox1 and Hmox2 in various diseases such as atherosclerosis, intimal hyperplasia, myocardial infarction, and angiogenesis. Finally, the therapeutic potential of heme oxygenases and their products are examined in a cardiovascular disease context, with a focus on how the knowledge we have gained on these enzymes may be capitalized in future clinical studies.
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Affiliation(s)
- Anita Ayer
- Vascular Biology Division, Victor Chang Cardiac Research Institute, Darlinghurst, Australia; and Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham Veterans Administration Medical Center, Birmingham, Alabama
| | - Abolfazl Zarjou
- Vascular Biology Division, Victor Chang Cardiac Research Institute, Darlinghurst, Australia; and Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham Veterans Administration Medical Center, Birmingham, Alabama
| | - Anupam Agarwal
- Vascular Biology Division, Victor Chang Cardiac Research Institute, Darlinghurst, Australia; and Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham Veterans Administration Medical Center, Birmingham, Alabama
| | - Roland Stocker
- Vascular Biology Division, Victor Chang Cardiac Research Institute, Darlinghurst, Australia; and Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham Veterans Administration Medical Center, Birmingham, Alabama
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Vukomanovic D, Rahman MN, Maines MD, Ozolinš TR, Szarek WA, Jia Z, Nakatsu K. Cysteine-independent activation/inhibition of heme oxygenase-2. Med Gas Res 2016; 6:10-13. [PMID: 27826418 PMCID: PMC5075677 DOI: 10.4103/2045-9912.179341] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Reactive thiols of cysteine (cys) residues in proteins play a key role in transforming chemical reactivity into a biological response. The heme oxygenase-2 (HO-2) isozyme contains two cys residues that have been implicated in binding of heme and also the regulation of its activity. In this paper, we address the question of a role for cys residues for the HO-2 inhibitors or activators designed in our laboratory. We tested the activity of full length recombinant human heme oxygenase-2 (FL-hHO-2) and its analog in which cys265 and cys282 were both replaced by alanine to determine the effect on activation by menadione (MD) and inhibition by QC-2350. Similar inhibition by QC-2350 and almost identical activation by MD was observed for both recombinant FL-hHO-2s. Our findings are interpreted to mean that thiols of FL-hHO-2s are not involved in HO-2 activation or inhibition by the compounds that have been designed and identified by us. Activation or inhibition of HO-2 by our compounds should be attributed to a mechanism other than altering binding affinity of HO-2 for heme through cys265 and cys282.
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Affiliation(s)
- Dragic Vukomanovic
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Mona N Rahman
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Mahin D Maines
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Terence Rs Ozolinš
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Walter A Szarek
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada
| | - Zongchao Jia
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Kanji Nakatsu
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Dunn LL, Midwinter RG, Ni J, Hamid HA, Parish CR, Stocker R. New insights into intracellular locations and functions of heme oxygenase-1. Antioxid Redox Signal 2014; 20:1723-42. [PMID: 24180287 PMCID: PMC3961787 DOI: 10.1089/ars.2013.5675] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 11/01/2013] [Indexed: 01/09/2023]
Abstract
SIGNIFICANCE Heme oxygenase-1 (HMOX1) plays a critical role in the protection of cells, and the inducible enzyme is implicated in a spectrum of human diseases. The increasing prevalence of cardiovascular and metabolic morbidities, for which current treatment approaches are not optimal, emphasizes the necessity to better understand key players such as HMOX1 that may be therapeutic targets. RECENT ADVANCES HMOX1 is a dynamic protein that can undergo post-translational and structural modifications which modulate HMOX1 function. Moreover, trafficking from the endoplasmic reticulum to other cellular compartments, including the nucleus, highlights that HMOX1 may play roles other than the catabolism of heme. CRITICAL ISSUES The ability of HMOX1 to be induced by a variety of stressors, in an equally wide variety of tissues and cell types, represents an obstacle for the therapeutic exploitation of the enzyme. Any capacity to modulate HMOX1 in cardiovascular and metabolic diseases should be tempered with an appreciation that HMOX1 may have an impact on cancer. Moreover, the potential for heme catabolism end products, such as carbon monoxide, to amplify the HMOX1 stress response should be considered. FUTURE DIRECTIONS A more complete understanding of HMOX1 modifications and the properties that they impart is necessary. Delineating these parameters will provide a clearer picture of the opportunities to modulate HMOX1 in human disease.
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Affiliation(s)
- Louise L. Dunn
- Vascular Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, Australia
- Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | | | - Jun Ni
- Vascular Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, Australia
- Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Hafizah A. Hamid
- Vascular Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, Australia
- Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Christopher R. Parish
- John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Roland Stocker
- Vascular Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, Australia
- Faculty of Medicine, The University of New South Wales, Sydney, Australia
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Vukomanovic D, Rahman MN, Bilokin Y, Golub AG, Brien JF, Szarek WA, Jia Z, Nakatsu K. In vitro Activation of heme oxygenase-2 by menadione and its analogs. Med Gas Res 2014; 4:4. [PMID: 24533775 PMCID: PMC3942077 DOI: 10.1186/2045-9912-4-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 02/10/2014] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Previously, we reported that menadione activated rat, native heme oxygenase-2 (HO-2) and human recombinant heme oxygenase-2 selectively; it did not activate spleen, microsomal heme oxygenase-1. The purpose of this study was to explore some structure-activity relationships of this activation and the idea that redox properties may be an important aspect of menadione efficacy. METHODS Heme oxygenase activity was determined in vitro using rat spleen and brain microsomes as the sources of heme oxygenase-1 and -2, respectively, as well as recombinant, human heme oxygenase-2. RESULTS Menadione analogs with bulky aliphatic groups at position-3, namely vitamins K1 and K2, were not able to activate HO-2. In contrast, several compounds with similar bulky but less lipophilic moieties at position-2 (and -3) were able to activate HO-2 many fold; these compounds included polar, rigid, furan-containing naphthoquinones, furan-benzoxazine naphthoquinones, 2-(aminophenylphenyl)-3-piperidin-1-yl naphthoquinones. To explore the idea that redox properties might be involved in menadione efficacy, we tested analogs such as 1,4-dimethoxy-2-methylnaphthalene, pentafluoromenadione, monohalogenated naphthoquinones, α-tetralone and 1,4-naphthoquinone. All of these compounds were inactive except for 1,4-naphthoquinone. Menadione activated full-length recombinant human heme oxygenase-2 (FL-hHO-2) as effectively as rat brain enzyme, but it did not activate rat spleen heme oxygenase. CONCLUSIONS These observations are consistent with the idea that naphthoquinones such as menadione bind to a receptor in HO-2 and activate the enzyme through a mechanism that may involve redox properties.
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Affiliation(s)
| | | | | | | | | | | | | | - Kanji Nakatsu
- Department of Biomedical & Molecular Sciences, School of Medicine, Queen's University, Kingston, ON K7L 3 N6, Canada.
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Nikam A, Patankar JV, Lackner C, Schöck E, Kratky D, Zatloukal K, Abuja PM. Transition between acute and chronic hepatotoxicity in mice is associated with impaired energy metabolism and induction of mitochondrial heme oxygenase-1. PLoS One 2013; 8:e66094. [PMID: 23762471 PMCID: PMC3675145 DOI: 10.1371/journal.pone.0066094] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/02/2013] [Indexed: 02/07/2023] Open
Abstract
The formation of protein inclusions is frequently associated with chronic metabolic diseases. In mice, short-term intoxication with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) leads to hepatocellular damage indicated by elevated serum liver enzyme activities, whereas only minor morphological changes are observed. Conversely, chronic administration of DDC for several weeks results in severe morphological damage, characterized by hepatocellular ballooning, disruption of the intermediate filament cytoskeleton, and formation of Mallory-Denk bodies consisting predominantly of misfolded keratins, Sqstm1/p62, and heat shock proteins. To evaluate the mechanistic underpinnings for this dichotomy we dissected the time-course of DDC intoxication for up to 10 weeks. We determined body weight change, serum liver enzyme activities, morphologic alterations, induction of antioxidant response (heme oxygenase-1, HO-1), oxidative damage and ATP content in livers as well as respiration, oxidative damage and the presence and activity of HO-1 in endoplasmic reticulum and mitochondria (mtHO-1). Elevated serum liver enzyme activity and oxidative liver damage were already present at early intoxication stages without further subsequent increase. After 2 weeks of intoxication, mice had transiently lost 9% of their body weight, liver ATP-content was reduced to 58% of controls, succinate-driven respiration was uncoupled from ATP-production and antioxidant response was associated with the appearance of catalytically active mtHO-1. Oxidative damage was associated with both acute and chronic DDC toxicity whereas the onset of chronic intoxication was specifically associated with mitochondrial dysfunction which was maximal after 2 weeks of intoxication. At this transition stage, adaptive responses involving mtHO-1 were induced, indirectly leading to improved respiration and preventing further drop of ATP levels. Our observations clearly demonstrate principally different mechanisms for acute and chronic toxic damage.
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Affiliation(s)
- Aniket Nikam
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Jay V. Patankar
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Carolin Lackner
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Elisabeth Schöck
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Dagmar Kratky
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Kurt Zatloukal
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Peter M. Abuja
- Institute of Pathology, Medical University of Graz, Graz, Austria
- * E-mail:
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15
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Ghosh MC, Ray AK. Membrane phospholipid augments cytochrome P4501a enzymatic activity by modulating structural conformation during detoxification of xenobiotics. PLoS One 2013; 8:e57919. [PMID: 23469105 PMCID: PMC3585281 DOI: 10.1371/journal.pone.0057919] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 01/27/2013] [Indexed: 12/08/2022] Open
Abstract
Cytochrome P450 is a superfamily of membrane-bound hemoprotein that gets involved with the degradation of xenobiotics and internal metabolites. Accumulated body of evidence indicates that phospholipids play a crucial role in determining the enzymatic activity of cytochrome P450 in the microenvironment by modulating its structure during detoxification; however, the structure-function relationship of cytochrome P4501A, a family of enzymes responsible for degrading lipophilic aromatic hydrocarbons, is still not well defined. Inducibility of cytochrome P4501A in cultured catfish hepatocytes in response to carbofuran, a widely used pesticide around the world, was studied earlier in our laboratory. In this present investigation, we observed that treating catfish with carbofuran augmented total phospholipid in the liver. We examined the role of phospholipid on the of cytochrome P4501A-marker enzyme which is known as ethoxyresorufin-O-deethylase (EROD) in the context of structure and function. We purified the carbofuran-induced cytochrome P4501A protein from catfish liver. Subsequently, we examined the enzymatic activity of purified P4501A protein in the presence of phospholipid, and studied how the structure of purified protein was influenced in the phospholipid environment. Membrane phospholipid appeared to accelerate the enzymatic activity of EROD by changing its structural conformation and thus controlling the detoxification of xenobiotics. Our study revealed the missing link of how the cytochrome P450 restores its enzymatic activity by changing its structural conformation in the phospholipid microenvironment.
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Affiliation(s)
- Manik C Ghosh
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
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16
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Rahman MN, Vukomanovic D, Vlahakis JZ, Szarek WA, Nakatsu K, Jia Z. Structural insights into human heme oxygenase-1 inhibition by potent and selective azole-based compounds. J R Soc Interface 2012; 10:20120697. [PMID: 23097500 DOI: 10.1098/rsif.2012.0697] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The development of heme oxygenase (HO) inhibitors, especially those that are isozyme-selective, promises powerful pharmacological tools to elucidate the regulatory characteristics of the HO system. It is already known that HO has cytoprotective properties and may play a role in several disease states, making it an enticing therapeutic target. Traditionally, the metalloporphyrins have been used as competitive HO inhibitors owing to their structural similarity with the substrate, heme. However, given heme's important role in several other proteins (e.g. cytochromes P450, nitric oxide synthase), non-selectivity is an unfortunate side-effect. Reports that azalanstat and other non-porphyrin molecules inhibited HO led to a multi-faceted effort to develop novel compounds as potent, selective inhibitors of HO. This resulted in the creation of non-competitive inhibitors with selectivity for HO, including a subset with isozyme selectivity for HO-1. Using X-ray crystallography, the structures of several complexes of HO-1 with novel inhibitors have been elucidated, which provided insightful information regarding the salient features required for inhibitor binding. This included the structural basis for non-competitive inhibition, flexibility and adaptability of the inhibitor binding pocket, and multiple, potential interaction subsites, all of which can be exploited in future drug-design strategies.
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Affiliation(s)
- Mona N Rahman
- 1Department of Biomedical and Molecular Sciences, and 2Department of Chemistry, Queen’s University, Kingston, Ontario, Canada
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17
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Sorrenti V, Guccione S, Di Giacomo C, Modica MN, Pittalà V, Acquaviva R, Basile L, Pappalardo M, Salerno L. Evaluation of Imidazole-Based Compounds as Heme Oxygenase-1 Inhibitors. Chem Biol Drug Des 2012; 80:876-86. [DOI: 10.1111/cbdd.12015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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18
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Linnenbaum M, Busker M, Kraehling JR, Behrends S. Heme oxygenase isoforms differ in their subcellular trafficking during hypoxia and are differentially modulated by cytochrome P450 reductase. PLoS One 2012; 7:e35483. [PMID: 22545110 PMCID: PMC3335857 DOI: 10.1371/journal.pone.0035483] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 03/16/2012] [Indexed: 11/30/2022] Open
Abstract
Heme oxygenase (HO) degrades heme in concert with NADPH cytochrome P450 reductase (CPR) which donates electrons to the reaction. Earlier studies reveal the importance of the hydrophobic carboxy-terminus of HO-1 for anchorage to the endoplasmic reticulum (ER) which facilitates the interaction with CPR. In addition, HO-1 has been shown to undergo regulated intramembrane proteolysis of the carboxy-terminus during hypoxia and subsequent translocation to the nucleus. Translocated nuclear HO-1 was demonstrated to alter binding of transcription factors and to alter gene expression. Little is known about the homologous membrane anchor of the HO-2 isoform. The current work is the first systematic analysis in a eukaryotic system that demonstrates the crucial role of the membrane anchor of HO-2 for localization at the endoplasmic reticulum, oligomerization and interaction with CPR. We show that although the carboxy-terminal deletion mutant of HO-2 is found in the nucleus, translocation of HO-2 to the nucleus does not occur under conditions of hypoxia. Thus, we demonstrate that proteolytic regulation and nuclear translocation under hypoxic conditions is specific for HO-1. In addition we show for the first time that CPR prevents this translocation and promotes oligomerization of HO-1. Based on these findings, CPR may modulate gene expression via the amount of nuclear HO-1. This is of particular relevance as CPR is a highly polymorphic gene and deficiency syndromes of CPR have been described in humans.
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Affiliation(s)
- Monika Linnenbaum
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig–Institute of Technology, Braunschweig, Germany
| | - Mareike Busker
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig–Institute of Technology, Braunschweig, Germany
| | - Jan R. Kraehling
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig–Institute of Technology, Braunschweig, Germany
| | - Soenke Behrends
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig–Institute of Technology, Braunschweig, Germany
- * E-mail:
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19
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Rahman MN, Vlahakis JZ, Vukomanovic D, Lee W, Szarek WA, Nakatsu K, Jia Z. A novel, "double-clamp" binding mode for human heme oxygenase-1 inhibition. PLoS One 2012; 7:e29514. [PMID: 22276118 PMCID: PMC3261875 DOI: 10.1371/journal.pone.0029514] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 11/29/2011] [Indexed: 11/23/2022] Open
Abstract
The development of heme oxygenase (HO) inhibitors is critical in dissecting and understanding the HO system and for potential therapeutic applications. We have established a program to design and optimize HO inhibitors using structure-activity relationships in conjunction with X-ray crystallographic analyses. One of our previous complex crystal structures revealed a putative secondary hydrophobic binding pocket which could be exploited for a new design strategy by introducing a functional group that would fit into this potential site. To test this hypothesis and gain further insights into the structural basis of inhibitor binding, we have synthesized and characterized 1-(1H-imidazol-1-yl)-4,4-diphenyl-2-butanone (QC-308). Using a carbon monoxide (CO) formation assay on rat spleen microsomes, the compound was found to be ∼15 times more potent (IC50 = 0.27±0.07 µM) than its monophenyl analogue, which is already a potent compound in its own right (QC-65; IC50 = 4.0±1.8 µM). The crystal structure of hHO-1 with QC-308 revealed that the second phenyl group in the western region of the compound is indeed accommodated by a definitive secondary proximal hydrophobic pocket. Thus, the two phenyl moieties are each stabilized by distinct hydrophobic pockets. This “double-clamp” binding offers additional inhibitor stabilization and provides a new route for improvement of human heme oxygenase inhibitors.
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Affiliation(s)
- Mona N. Rahman
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | | | - Dragic Vukomanovic
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | - Wallace Lee
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | | | - Kanji Nakatsu
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
- * E-mail:
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20
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Mutations of human cytochrome P450 reductase differentially modulate heme oxygenase-1 activity and oligomerization. Arch Biochem Biophys 2011; 513:42-50. [PMID: 21741353 DOI: 10.1016/j.abb.2011.06.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 06/14/2011] [Accepted: 06/16/2011] [Indexed: 01/26/2023]
Abstract
Genetic variations in POR, encoding NADPH-cytochrome P450 oxidoreductase (CYPOR), can diminish the function of numerous cytochromes P450, and also have the potential to block degradation of heme by heme oxygenase-1 (HO-1). Purified full-length human CYPOR, HO-1, and biliverdin reductase were reconstituted in lipid vesicles and assayed for NADPH-dependent conversion of heme to bilirubin. Naturally-occurring human CYPOR variants queried were: WT, A115V, Y181D, P228L, M263V, A287P, R457H, Y459H, and V492E. All CYPOR variants exhibited decreased bilirubin production relative to WT, with a lower apparent affinity of the CYPOR-HO-1 complex than WT. Addition of FMN or FAD partially restored the activities of Y181D, Y459H, and V492E. When mixed with WT CYPOR, only the Y181D CYPOR variant inhibited heme degradation by sequestering HO-1, whereas Y459H and V492E were unable to inhibit HO-1 activity suggesting that CYPOR variants might have differential binding affinities with redox partners. Titrating the CYPOR-HO-1 complex revealed that the optimal CYPOR:HO-1 ratio for activity was 1:2, lending evidence in support of productive HO-1 oligomerization, with higher ratios of CYPOR:HO-1 showing decreased activity. In conclusion, human POR mutations, shown to impact P450 activities, also result in varying degrees of diminished HO-1 activity, which may further complicate CYPOR deficiency.
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21
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Choi YG, Seok YH, Yeo S, Jeong MY, Lim S. Protective changes of inflammation-related gene expression by the leaves of Eriobotrya japonica in the LPS-stimulated human gingival fibroblast: microarray analysis. JOURNAL OF ETHNOPHARMACOLOGY 2011; 135:636-645. [PMID: 21473904 DOI: 10.1016/j.jep.2011.03.066] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 03/18/2011] [Accepted: 03/29/2011] [Indexed: 05/30/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The leaf of Eriobotrya japonica (Ej) has been used for a long time as an oriental medicine to treat pulmonary inflammatory diseases. This study investigated the gene expression changes by lipopolysaccharide (LPS) stimulation in the cultured human gingival fibroblast and the anti-inflammatory changes of the genes by the leaves of Ej when challenged with LPS using a microarray chip. MATERIALS AND METHODS A whole transcript genechip (Affymetrix genechip human gene 1.0 ST array) was used. The expression patterns of the significant genes were confirmed by real-time RT-PCR analysis. RESULTS The gene array analysis showed that 60 of the 325 genes up-regulated by the LPS when compared to the control were down-regulated by the Ej treatment. Of these 60 genes, the inflammation- and immune response-related genes were especially noted, which indicates that Ej inhibits the induction of the inflammation through LPS stimulation. In addition, 78 of the 158 genes down-regulated by the LPS when compared to the control were up-regulated by the Ej treatment. The regulatory patterns of the representative genes in the real-time RT-PCR correlated with those of the genes shown in the microarray. The Ej extract also inhibited the production of IL-6, TNF-α, and nitrite in the LPS-stimulated cells. CONCLUSIONS This study showed that the extract of Ej leaves could be used to inhibit the activation of a wide variety of the inflammation-related genes and the inflammatory mediators. It is suggested that the extract of Ej leaves may be applied to alleviate the inflammation of periodontal diseases.
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Affiliation(s)
- Yeong-Gon Choi
- Research Group of Pain and Neuroscience, WHO Collaborating Center for Traditional Medicine, East-West Medical Research Institute, Kyung Hee University, Seoul 130-701, Republic of Korea
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22
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Reed JR, Cawley GF, Backes WL. Inhibition of cytochrome P450 1A2-mediated metabolism and production of reactive oxygen species by heme oxygenase-1 in rat liver microsomes. Drug Metab Lett 2011; 5:6-16. [PMID: 20942796 DOI: 10.2174/187231211794455253] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 10/05/2010] [Indexed: 11/22/2022]
Abstract
Heme oxygenase-1 (HO-1) is induced in most cell types by many forms of environmental stress and is believed to play a protective role in cells exposed to oxidative stress. Metabolism by cytochromes P450 (P450) is highly inefficient as the oxidation of substrate is associated with the production of varying proportions of hydrogen peroxide and/or superoxide. This study tests the hypothesis that heme oxygenase-1 (HO-1) plays a protective role against oxidative stress by competing with P450 for binding to the common redox partner, the NADPH P450 reductase (CPR) and in the process, diminishing P450 metabolism and the associated production of reactive oxygen species (ROS). Liver microsomes were isolated from uninduced rats and rats that were treated with cadmium and/or β-napthoflavone (BNF) to induce HO-1 and/or CYP1A2. HO-1 induction was associated with slower rates of metabolism of the CYP1A2-specific substrate, 7-ethoxyresorufin. Furthermore, HO-1 induction also was associated with slower rates of hydrogen peroxide and hydroxyl radical production by microsomes from rats induced for CYP1A2. The inhibition associated with HO-1 induction was not dependent on the addition of heme to the microsomal incubations. The effects of HO-1 induction were less dramatic in the absence of substrate for CYP1A2, suggesting that the enzyme was more effective in inhibiting the CYP1A2-related activity than the CPR-related production of superoxide (that dismutates to form hydrogen peroxide).
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Affiliation(s)
- James R Reed
- Department of Pharmacology and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, 1901 Perdido St., New Orleans, LA 70112, USA.
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23
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Hwang HW, Lee JR, Chou KY, Suen CS, Hwang MJ, Chen C, Shieh RC, Chau LY. Oligomerization is crucial for the stability and function of heme oxygenase-1 in the endoplasmic reticulum. J Biol Chem 2009; 284:22672-9. [PMID: 19556236 DOI: 10.1074/jbc.m109.028001] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heme oxygenase-1 (HO-1), a stress-inducible enzyme anchored in the endoplasmic reticulum (ER) by a single transmembrane segment (TMS) located at the C terminus, interacts with NADPH cytochrome P450 reductase and biliverdin reductase to catalyze heme degradation to biliverdin and its metabolite, bilirubin. Previous studies suggested that HO-1 functions as a monomer. Using chemical cross-linking, co-immunoprecipitation, and fluorescence resonance energy transfer (FRET) experiments, here we showed that HO-1 forms dimers/oligomers in the ER. However, oligomerization was not observed with a truncated HO-1 lacking the C-terminal TMS (amino acids 266-285), which exhibited cytosolic and nuclear localization, indicating that the TMS is essential for the self-assembly of HO-1 in the ER. To identify the interface involved in the TMS-TMS interaction, residue Trp-270, predicted by molecular modeling as a potential interfacial residue of TMS alpha-helices, was mutated, and the effects on protein subcellular localization and activity assessed. The results showed that the W270A mutant was present exclusively in the ER and formed oligomers with similar activity to those of the wild type HO-1. Interestingly, the W270N mutant was localized not only in the ER, but also in the cytosol and nucleus, suggesting it is susceptible to proteolytic cleavage. Moreover, the microsomal HO activity of the W270N mutant was significantly lower than that of the wild type. The W270N mutation appears to interfere with the oligomeric state, as revealed by a lower FRET efficiency. Collectively, these data suggest that oligomerization, driven by TMS-TMS interactions, is crucial for the stabilization and function of HO-1 in the ER.
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Affiliation(s)
- Hsuan-Wen Hwang
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
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Xie H, Guo XM, Chen H. Making the most of fusion tags technology in structural characterization of membrane proteins. Mol Biotechnol 2009; 42:135-45. [PMID: 19199085 DOI: 10.1007/s12033-009-9148-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Accepted: 01/19/2009] [Indexed: 11/24/2022]
Abstract
Membrane proteins can be investigated at various structural levels, including the topological structure, the high-resolution three-dimensional structure, and the organization and assembly of membrane protein complexes. Gene fusion technology makes it possible to insert a polynucleotide encoding a protein or polypeptide tag into the gene encoding a membrane protein of interest. Resultant recombinant proteins may possess the functions of the original membrane proteins, together with the biochemical properties of the imported fusion tag, greatly enhancing functional and structural studies of membrane proteins. In this article, the latest literature is reviewed in relation to types, applications, strategies, and approaches to fusion tag technology for structural investigations of membrane proteins.
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Affiliation(s)
- Hao Xie
- Department of Biological Science and Biotechnology, Institute of Science, Wuhan University of Technology, People's Republic of China.
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25
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Huber Iii WJ, Scruggs BA, Backes WL. C-Terminal membrane spanning region of human heme oxygenase-1 mediates a time-dependent complex formation with cytochrome P450 reductase. Biochemistry 2009; 48:190-7. [PMID: 19123922 DOI: 10.1021/bi801912z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Heme oxygenase-1 (HO-1) catalyzes the oxidative degradation of heme to biliverdin, carbon monoxide, and free iron in a reaction requiring the interaction of HO-1 with NADPH-cytochrome P450 reductase (CPR). HO-1 is bound to the endoplasmic reticulum by 23 C-terminal amino acids; however, a soluble HO-1 (sHO-1) lacking this membrane spanning region has been extensively studied. The goal of this project was to characterize the effect of the C-terminal hydrophobic domain on formation of the HO-1/CPR complex. Full-length HO-1 was shown to exhibit higher reaction rates than sHO-1, particularly at subsaturating CPR, indicating that the C-terminal region influences HO-1 binding to CPR. The increased activity of HO-1 was attributable to a time-dependent formation of a low K(m) HO-1/CPR complex that was not seen with sHO1. Gel filtration analysis confirmed the formation of multiple high molecular weight complexes in the presence and absence of the synthetic lipid dilauroylphosphatidylcholine (DLPC). However, the largest complex appeared following a 2 h incubation of HO-1 and CPR in DLPC, suggesting that the C-terminal region was required for the high-affinity HO-1/CPR complex formation and membrane incorporation. These data demonstrate that the C-terminal region of HO-1 influenced complex formation and ultimately its affinity for CPR.
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Affiliation(s)
- Warren J Huber Iii
- Department of Pharmacology and The Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, 533 Bolivar Street, New Orleans, Louisiana 70112
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26
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Huber WJ, Marohnic CC, Peters M, Alam J, Reed JR, Masters BSS, Backes WL. Measurement of membrane-bound human heme oxygenase-1 activity using a chemically defined assay system. Drug Metab Dispos 2009; 37:857-64. [PMID: 19131520 DOI: 10.1124/dmd.108.025023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heme oxygenase (HO) catalyzes heme degradation in a reaction requiring NADPH-cytochrome P450 reductase (CPR). Although most studies with HO used a soluble 30-kDa form, lacking the C-terminal membrane-binding region, recent reports show that the catalytic behavior of this enzyme is very different if this domain is retained; the overall activity was elevated 5-fold, and the K(m) for CPR decreased approximately 50-fold. The goal of these studies was to accurately measure HO activity using a coupled assay containing purified biliverdin reductase (BVR). This allows measurement of bilirubin formation after incorporation of full-length CPR and heme oxygenase-1 (HO-1) into a membrane environment. When rat liver cytosol was used as the source of partially purified BVR, the reaction remained linear for 2 to 3 min; however, the reaction was only linear for 10 to 30 s when an equivalent amount of purified, human BVR (hBVR) was used. This lack of linearity was not observed with soluble HO-1. Optimal formation of bilirubin was achieved with concentrations of bovine serum albumin (0.25 mg/ml) and hBVR (0.025-0.05 microM), but neither supplement increased the time that the reaction remained linear. Various concentrations of superoxide dismutase had no effect on the reaction; however, when catalase was included, the reactions were linear for at least 4 to 5 min, even at high CPR levels. These results not only show that HO-1-generated hydrogen peroxide leads to a decrease in HO-1 activity but also provide for a chemically defined system to be used to examine the function of full-length HO-1 in a membrane environment.
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Affiliation(s)
- Warren J Huber
- Department of Pharmacology and The Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, 533 Bolivar Street, New Orleans, LA 70112, USA
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