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Baum O. Expression of neuronal NO synthase α- and β-isoforms in skeletal muscle of mice. Biochem J 2024; 481:601-613. [PMID: 38592741 DOI: 10.1042/bcj20230458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 03/27/2024] [Accepted: 04/09/2024] [Indexed: 04/10/2024]
Abstract
Knowledge of the primary structure of neuronal NO synthase (nNOS) in skeletal muscle is still conflicting and needs further clarification. To elucidate the expression patterns of nNOS isoforms at both mRNA and protein level, systematic reverse transcription (RT)-PCR and epitope mapping by qualitative immunoblot analysis on skeletal muscle of C57/BL6 mice were performed. The ability of the nNOS isoforms to form aggregates was characterized by native low-temperature polyacrylamide electrophoresis (LT-PAGE). The molecular analysis was focused on the rectus femoris (RF) muscle, a skeletal muscle with a nearly balanced ratio of nNOS α- and β-isoforms. RT-PCR amplificates from RF muscles showed exclusive exon-1d mRNA expression, either with or without exon-μ. Epitope mapping demonstrated the simultaneous expression of the nNOS splice variants α/μ, α/non-μ, β/μ and β/non-μ. Furthermore, immunoblotting suggests that the transition between nNOS α- and β-isoforms lies within exon-3. In LT-PAGE, three protein nNOS associated aggregates were detected in homogenates of RF muscle and tibialis anterior muscle: a 320 kDa band containing nNOS α-isoforms, while 250 and 300 kDa bands consist of nNOS β-isoforms that form homodimers or heterodimers with non-nNOS proteins.
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Affiliation(s)
- Oliver Baum
- Institute of Physiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany
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2
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Lisberg A, Liu Y, Merry DE. Blocking the dimerization of polyglutamine-expanded androgen receptor protects cells from DHT-induced toxicity by increasing AR turnover. J Biol Chem 2024; 300:107246. [PMID: 38556081 PMCID: PMC11067348 DOI: 10.1016/j.jbc.2024.107246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 03/06/2024] [Accepted: 03/15/2024] [Indexed: 04/02/2024] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular degenerative disease caused by a polyglutamine expansion in the androgen receptor (AR). This mutation causes AR to misfold and aggregate, contributing to toxicity in and degeneration of motor neurons and skeletal muscle. There is currently no effective treatment or cure for this disease. The role of an interdomain interaction between the amino- and carboxyl-termini of AR, termed the N/C interaction, has been previously identified as a component of androgen receptor-induced toxicity in cell and mouse models of SBMA. However, the mechanism by which this interaction contributes to disease pathology is unclear. This work seeks to investigate this mechanism by interrogating the role of AR homodimerization- a unique form of the N/C-interaction- in SBMA. We show that, although the AR N/C-interaction is reduced by polyglutamine-expansion, homodimers of 5α-dihydrotestosterone (DHT)-bound AR are increased. Additionally, blocking homodimerization results in decreased AR aggregation and toxicity in cell models. Blocking homodimerization results in the increased degradation of AR, which likely plays a role in the protective effects of this mutation. Overall, this work identifies a novel mechanism in SBMA pathology that may represent a novel target for the development of therapeutics for this disease.
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Affiliation(s)
- Allison Lisberg
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Yuhong Liu
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Diane E Merry
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
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Kanzaki K, Wada M. Arginine ingestion inhibits phagocyte invasion in eccentrically contracted rat fast-twitch muscle. J Muscle Res Cell Motil 2024:10.1007/s10974-024-09672-w. [PMID: 38635146 DOI: 10.1007/s10974-024-09672-w] [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: 01/31/2024] [Accepted: 03/29/2024] [Indexed: 04/19/2024]
Abstract
Eccentric contraction (ECC) has been shown to induce leukocyte invasion into skeletal muscle, resulting in muscle inflammation. This study aimed to investigate whether prior ingestion of L-arginine (ARG), a nitric oxide precursor, inhibits ECC-induced macrophage invasion. Male Wistar rats received ARG in water for 7 days, beginning 3 days prior to ECC. ECCs were induced in the anterior crural muscles for 200 cycles. Three days later, the tibialis anterior and extensor digitorum longus muscles were excised for biochemical analysis and force measurement, respectively. ARG ingestion increased nitrite and nitrate levels in plasma and muscle, inhibiting force depression and reducing CD68 content in muscles subjected to ECC. ARG ingestion also ameliorated an ECC-induced increase in protein nitration, although neither ARG ingestion nor ECC induction affected protein carbonyl levels. The present results suggest that ingestion of ARG or ARG-rich foods may alleviate inflammation by attenuating phagocyte invasion in eccentrically contracted skeletal muscles.
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Affiliation(s)
- Keita Kanzaki
- Department of Clinical Nutrition, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, Okayama, 701-0193, Japan
| | - Masanobu Wada
- Graduate School of Humanities and Social Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima, 739-8521, Japan.
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Zhang W, Chen SJ, Guo LY, Zhang Z, Zhang JB, Wang XM, Meng XB, Zhang MY, Zhang KK, Chen LL, Li YW, Wen Y, Wang L, Hu JH, Bai YY, Zhang XJ. Nitric oxide synthase and its function in animal reproduction: an update. Front Physiol 2023; 14:1288669. [PMID: 38028794 PMCID: PMC10662090 DOI: 10.3389/fphys.2023.1288669] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 10/24/2023] [Indexed: 12/01/2023] Open
Abstract
Nitric oxide (NO), a free radical labile gas, is involved in the regulation of various biological functions and physiological processes during animal reproduction. Recently, increasing evidence suggests that the biological role and chemical fate of NO is dependent on dynamic regulation of its biosynthetic enzyme, three distinct nitric oxide synthase (NOS) according to their structure, location and function. The impact of NOS isoforms on reproductive functions need to be timely elucidated. Here, we focus on and the basic background and latest studies on the development, structure, importance inhibitor, location pattern, complex functions. Moreover, we summarize the exactly mechanisms which involved some cell signal pathways in the regulation of NOS with cellular and molecular level in the animal reproduction. Therefore, this growing research area provides the new insight into the important role of NOS male and female reproduction system. It also provides the treatment evidence on targeting NOS of reproductive regulation and diseases.
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Affiliation(s)
- Wei Zhang
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Su juan Chen
- Department of Life Science and Technology, Xinxiang Medical College, Xinxiang, Henan, China
| | - Li ya Guo
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Zijing Zhang
- Institute of Animal Husbandry and Veterinary Science, Henan Academy of Agricultural Sciences, Zhengzhou, Henan, China
| | - Jia bin Zhang
- College of Veterinary Medicine, Jilin Agriculture University, Changchun, China
| | - Xiao meng Wang
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Xiang bo Meng
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Min ying Zhang
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Ke ke Zhang
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Lin lin Chen
- College of Veterinary Medicine, Jilin Agriculture University, Changchun, China
| | - Yi wei Li
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Yuliang Wen
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Lei Wang
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Jian he Hu
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
| | - Yue yu Bai
- Animal Health Supervision in Henan Province, Zhengzhou, Henan, China
| | - Xiao jian Zhang
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan, China
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Mirza I, Haloul M, Hassan C, Masrur M, Mostafa A, Bianco FM, Ali MM, Minshall RD, Mahmoud AM. Adiposomes from Obese-Diabetic Individuals Promote Endothelial Dysfunction and Loss of Surface Caveolae. Cells 2023; 12:2453. [PMID: 37887297 PMCID: PMC10605845 DOI: 10.3390/cells12202453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 10/08/2023] [Accepted: 10/10/2023] [Indexed: 10/28/2023] Open
Abstract
Glycosphingolipids (GSLs) are products of lipid glycosylation that have been implicated in the development of cardiovascular diseases. In diabetes, the adipocyte microenvironment is characterized by hyperglycemia and inflammation, resulting in high levels of GSLs. Therefore, we sought to assess the GSL content in extracellular vesicles derived from the adipose tissues (adiposomes) of obese-diabetic (OB-T2D) subjects and their impact on endothelial cell function. To this end, endothelial cells were exposed to adiposomes isolated from OB-T2D versus healthy subjects. Cells were assessed for caveolar integrity and related signaling, such as Src-kinase and caveolin-1 (cav-1) phosphorylation, and functional pathways, such as endothelial nitric oxide synthase (eNOS) activity. Compared with adiposomes from healthy subjects, OB-T2D adiposomes had higher levels of GSLs, especially LacCer and GM3; they promoted cav-1 phosphorylation coupled to an obvious loss of endothelial surface caveolae and induced eNOS-uncoupling, peroxynitrite generation, and cav-1 nitrosylation. These effects were abolished by Src kinase inhibition and were not observed in GSL-depleted adiposomes. At the functional levels, OB-T2D adiposomes reduced nitric oxide production, shear response, and albumin intake in endothelial cells and impaired flow-induced dilation in healthy arterioles. In conclusion, OB-T2D adiposomes carried a detrimental GSL cargo that disturbed endothelial caveolae and the associated signaling.
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Affiliation(s)
- Imaduddin Mirza
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA; (I.M.); (M.H.)
| | - Mohamed Haloul
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA; (I.M.); (M.H.)
| | - Chandra Hassan
- Department of Surgery, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA; (C.H.); (M.M.); (F.M.B.); (R.D.M.)
| | - Mario Masrur
- Department of Surgery, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA; (C.H.); (M.M.); (F.M.B.); (R.D.M.)
| | - Amro Mostafa
- Departments of Anesthesiology and Pharmacology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA;
| | - Francesco M. Bianco
- Department of Surgery, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA; (C.H.); (M.M.); (F.M.B.); (R.D.M.)
| | - Mohamed M. Ali
- School of Business and Non-Profit Management, North Park University, Chicago, IL 60625, USA;
| | - Richard D. Minshall
- Department of Surgery, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA; (C.H.); (M.M.); (F.M.B.); (R.D.M.)
| | - Abeer M. Mahmoud
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA; (I.M.); (M.H.)
- Department of Kinesiology and Nutrition, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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6
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Quantitative chemoproteomics reveals O-GlcNAcylation of cystathionine γ-lyase (CSE) represses trophoblast syncytialization. Cell Chem Biol 2021; 28:788-801.e5. [PMID: 33626323 DOI: 10.1016/j.chembiol.2021.01.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 01/08/2021] [Accepted: 01/28/2021] [Indexed: 12/24/2022]
Abstract
Emerging evidence indicates the involvement of O-GlcNAc modification in placental development and pregnant health through mechanisms that are not well understood. Herein, by applying the quantitative O-GlcNAc proteomics, we established a database of O-GlcNAcylated proteins in human placental trophoblasts. Hundreds of proteins that were dynamically O-GlcNAcylated during trophoblast differentiation were identified, among which cystathionine γ-lyase (CSE) exhibited the most significant change. Site-specific analysis by mass spectrometry revealed Ser138 as the core O-GlcNAc site in CSE, and its O-GlcNAcylation promoted the enzymatic activity to produce H2S, which in turn repressed trophoblast differentiation via inhibiting androgen receptor dimerization. Consistently, in preeclamptic placentas, remarkably enhanced CSE O-GlcNAcylation and H2S production were associated with restricted trophoblast differentiation. The findings establish a resource of O-GlcNAc dynamics in human placenta, and provide a deeper insight into the biological significance of O-GlcNAcylation in placental development as well as potential therapeutic targets for the relevant pregnant complications.
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Saini R, Azam Z, Sapra L, Srivastava RK. Neuronal Nitric Oxide Synthase (nNOS) in Neutrophils: An Insight. Rev Physiol Biochem Pharmacol 2021; 180:49-83. [PMID: 34115206 DOI: 10.1007/112_2021_61] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
NO (nitric oxide) is an important regulator of neutrophil functions and has a key role in diverse pathophysiological conditions. NO production by nitric oxide synthases (NOS) is under tight control at transcriptional, translational, and post-translational levels including interactions with heterologous proteins owing to its potent chemical reactivity and high diffusibility; this limits toxicity to other cellular components and promotes signaling specificity. The protein-protein interactions govern the activity and spatial distribution of NOS isoform to regulatory proteins and to their intended targets. In comparison with the vast literature available for endothelial, macrophages, and neuronal cells, demonstrating neuronal NOS (nNOS) interaction with other proteins through the PDZ domain, neutrophil nNOS, however, remains unexplored. Neutrophil's key role in both physiological and pathological conditions necessitates the need for further studies in delineating the NOS mediated NO modulations in signaling pathways operational in them. nNOS has been linked to depression, schizophrenia, and Parkinson's disease, suggesting the importance of exploring nNOS/NO-mediated neutrophil physiology in relation to such neuronal disorders. The review thus presents the scenario of neutrophil nNOS from the genetics to the functional level, including protein-protein interactions governing its intracellular sequestration in diverse cell types, besides speculating possible regulation in neutrophils and also addressing their clinical implications.
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Affiliation(s)
- Rashmi Saini
- Department of Zoology, Gargi College, University of Delhi, Delhi, India.
| | - Zaffar Azam
- Department of Zoology, Dr. Harisingh Gour Central University, Sagar, MP, India
- Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi, India
| | - Leena Sapra
- Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi, India
| | - Rupesh K Srivastava
- Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi, India.
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Xiong W, Kong X, Jiang J, Yang Z, Jiang R. Low androgen status inhibits erectile function by inducing eNOS uncoupling in rat corpus cavernosum. Andrology 2020; 8:1875-1883. [PMID: 32594586 DOI: 10.1111/andr.12844] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 05/12/2020] [Accepted: 06/17/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND The number of erectile dysfunction (ED) patients is increasing annually. How to improve the effectiveness of ED treatment is an important issue for the field of andrology. OBJECTIVES To investigate whether low androgen status impairs the erectile function of rats by regulated endothelial nitric oxide synthase (eNOS) uncoupling. MATERIALS AND METHODS Thirty-six 8-week-old male Sprague Dawley (SD) rats were randomly divided into six groups as follows: 4-week sham-operated group (4w-sham), 4-week castration group (4w-cast), 4-week castration + testosterone (T) group (4w-cast + T), 8-week sham-operated group (8w-sham), 8-week castration group (8w-cast), and 8-week castration + T group (8w-cast + T). Three mg/kg of T was subcutaneously injected every other day in castration + T groups. The ratio of the maximum intracavernous pressure/the mean arterial pressure (ICPmax/MAP), the level of serum T, dihydrobiopterin(BH2 ), tetrahydrobiopterin (BH4 ), nitric oxygen(NO), 3-nitrotyrosine(3NT), dihydrofolate reductase (DHFR), guanosine triphosphate cyclohydrolase 1 (GTPCH1), nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2), and eNOS monomers/dimers in the corpus cavernosum were detected. RESULTS The ratio of ICPmax/MAP and BH4 /BH2 , the level of serum T, NO, and GTPCH1 decreased significantly in castration groups compared with sham-operated groups and castration + T groups (P < .05) and decreased significantly in 8w-cast group compared with 4w-cast group (P < .05). The expression of 3NT and NOX2 and the ratio of eNOS monomers/dimers increased significantly in castration groups compared with sham-operated groups and castration + T groups (P < .01) and increased significantly in 8w-cast group compared with 4w-cast group (P < .01). The expression of DHFR in 4w-cast group was significantly higher than that in 4w-sham group and 4w-cast + T group (P < .01) and in 8w-cast group was significantly lower than that in 8w-sham group and 8w-cast + T group (P < .01). DISCUSSION AND CONCLUSION Low androgen status induces eNOS uncoupling by reducing BH4 /BH2 and increasing 3NT. Due to the decreased NO production, the erectile function of the rats was impaired.
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Affiliation(s)
- Wenju Xiong
- Department of Urology, the Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Xiangjun Kong
- Department of Urology, the Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Jun Jiang
- Department of Thyroid Surgery, the Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Zhihui Yang
- Department of Pathology, the Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Rui Jiang
- Department of Urology, the Affiliated Hospital of Southwest Medical University, Luzhou, China.,Nephropathy Clinical Medical Research Center of Sichuan Province, Luzhou, China
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Mittal A, Kakkar R. Nitric Oxide Synthases and Their Inhibitors: A Review. LETT DRUG DES DISCOV 2020. [DOI: 10.2174/1570180816666190222154457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric Oxide (NO), an important biological mediator, is involved in the regulation of the cardiovascular, nervous and immune systems in mammals. Synthesis of NO is catalyzed by its biosynthetic enzyme, Nitric Oxide Synthase (NOS). There are three main isoforms of the enzyme, neuronal NOS, endothelial NOS and inducible NOS, which have very similar structures but differ in their expression and activities. NO is produced in the active site of the enzyme in two distinct cycles from oxidation of the substrate L-arg (L-arginine) in nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reaction. NOS has gained considerable attention of biochemists due to its complexity and unique catalytic mechanism. The review focuses on NOS structure, its function and catalytic reaction mechanism. In particular, the review is concluded with a discussion on the role of all three isoforms of NOS in physiological and pathological conditions and their inhibitors with a focus on the role of computational techniques in their development.
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Affiliation(s)
- Anshika Mittal
- Computational Chemistry Laboratory, Department of Chemistry, University of Delhi, Delhi-110007, India
| | - Rita Kakkar
- Computational Chemistry Laboratory, Department of Chemistry, University of Delhi, Delhi-110007, India
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Sharma NM, Haibara AS, Katsurada K, Liu X, Patel KP. Central angiotensin II-Protein inhibitor of neuronal nitric oxide synthase (PIN) axis contribute to neurogenic hypertension. Nitric Oxide 2019; 94:54-62. [PMID: 31654775 DOI: 10.1016/j.niox.2019.10.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/17/2019] [Accepted: 10/17/2019] [Indexed: 02/07/2023]
Abstract
Activation of renin-angiotensin- system, nitric oxide (NO•) bioavailability and subsequent sympathoexcitation plays a pivotal role in the pathogenesis of many cardiovascular diseases, including hypertension. Previously we have shown increased protein expression of PIN (a protein inhibitor of nNOS: neuronal nitric oxide synthase, known to dissociate nNOS dimers into monomers) with concomitantly reduced levels of catalytically active dimers of nNOS in the PVN of rats with heart failure. To elucidate the molecular mechanism by which Angiotensin II (Ang II) increases PIN expression, we used Sprague-Dawley rats (250-300 g) subjected to intracerebroventricular infusion of Ang II (20 ng/min, 0.5 μl/h) or saline as vehicle (Veh) for 14 days through osmotic mini-pumps and NG108-15 hybrid neuronal cell line treated with Ang II as an in vitro model. Ang II infusion significantly increased baseline renal sympathetic nerve activity and mean arterial pressure. Ang II infusion increased the expression of PIN (1.24 ± 0.04* Ang II vs. 0.65 ± 0.07 Veh) with a concomitant 50% decrease in dimeric nNOS and PIN-Ub conjugates (0.73 ± 0.04* Ang II vs. 1.00 ± 0.03 Veh) in the PVN. Substrate-dependent ligase assay in cells transfected with pCMV-(HA-Ub)8 vector revealed a reduction of HA-Ub-PIN conjugates after Ang II and a proteasome inhibitor, Lactacystin (LC), treatment (4.5 ± 0.7* LC Ang II vs. 9.2 ± 2.5 LC). TUBE (Tandem Ubiquitin-Binding Entities) assay showed decrease PIN-Ub conjugates in Ang II-treated cells (0.82 ± 0.12* LC Ang II vs. 1.21 ± 0.06 LC) while AT1R blocker, Losartan (Los) treatment diminished the Ang II-mediated stabilization of PIN (1.21 ± 0.07 LC Los vs. 1.16 ± 0.04* LC Ang II Los). Taken together, our studies suggest that increased central levels of Ang II contribute to the enhanced expression of PIN leading to reduced expression of the dimeric form of nNOS, thus diminishing the inhibitory action of NO• on pre-autonomic neurons in the PVN resulting in increased sympathetic outflow.
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Affiliation(s)
- Neeru M Sharma
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, 68198-5850, USA.
| | - Andrea S Haibara
- Department of Physiology and Biophysics, University of Minas Gerais, Belo Horizonte, MG, 31270-910, Brazil
| | - Kenichi Katsurada
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, 68198-5850, USA
| | - Xuefei Liu
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, 68198-5850, USA
| | - Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, 68198-5850, USA
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Gebhart V, Reiß K, Kollau A, Mayer B, Gorren ACF. Site and mechanism of uncoupling of nitric-oxide synthase: Uncoupling by monomerization and other misconceptions. Nitric Oxide 2019; 89:14-21. [PMID: 31022534 DOI: 10.1016/j.niox.2019.04.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 03/15/2019] [Accepted: 04/15/2019] [Indexed: 01/20/2023]
Abstract
Nitric oxide synthase (NOS) catalyzes the transformation of l-arginine, molecular oxygen (O2), and NADPH-derived electrons to nitric oxide (NO) and l-citrulline. Under some conditions, however, NOS catalyzes the reduction of O2 to superoxide (O2-) instead, a phenomenon that is generally referred to as uncoupling. In principle, both the heme in the oxygenase domain and the flavins in the reductase domain could catalyze O2- formation. In the former case the oxyferrous (Fe(II)O2) complex that is formed as an intermediate during catalysis would dissociate to heme and O2-; in the latter case the reduced flavins would reduce O2 to O2-. The NOS cofactor tetrahydrobiopterin (BH4) is indispensable for coupled catalysis. In the case of uncoupling at the heme this is explained by the essential role of BH4 as an electron donor to the oxyferrous complex; in the case of uncoupling at the flavins it is assumed that the absence of BH4 results in NOS monomerization, with the monomers incapable to sustain NO synthesis but still able to support uncoupled catalysis. In spite of little supporting evidence, uncoupling at the reductase after NOS monomerization appears to be the predominant hypothesis at present. To set the record straight we extended prior studies by determining under which conditions uncoupling of the neuronal and endothelial isoforms (nNOS and eNOS) occurred and if a correlation exists between uncoupling and the monomer/dimer equilibrium. We determined the rates of coupled/uncoupled catalysis by measuring NADPH oxidation spectrophotometrically at 340 nm and citrulline synthesis as the formation of [3H]-citrulline from [3H]-Arg. The monomer/dimer equilibrium was determined by FPLC and, for comparison, by low-temperature polyacrylamide gel electrophoresis. Uncoupling occurred in the absence of Arg and/or BH4, but not in the absence of Ca2+ or calmodulin (CaM). Since omission of Ca2+/CaM will completely block heme reduction while still allowing substantial FMN reduction, this argues against uncoupling by the reductase domain. In the presence of heme-directed NOS inhibitors uncoupling occurred to the extent that these compound allowed heme reduction, again arguing in favor of uncoupling at the heme. The monomer/dimer equilibrium showed no correlation with uncoupling. We conclude that uncoupling by BH4 deficiency takes place exclusively at the heme, with virtually no contribution from the flavins and no role for NOS monomerization.
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Affiliation(s)
- Verena Gebhart
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Katja Reiß
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Alexander Kollau
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Bernd Mayer
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Antonius C F Gorren
- Department of Pharmacology and Toxicology Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria.
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Sharma NM, Liu X, Llewellyn TL, Katsurada K, Patel KP. Exercise training augments neuronal nitric oxide synthase dimerization in the paraventricular nucleus of rats with chronic heart failure. Nitric Oxide 2019; 87:73-82. [PMID: 30878404 PMCID: PMC6527363 DOI: 10.1016/j.niox.2019.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 02/06/2019] [Accepted: 03/08/2019] [Indexed: 12/20/2022]
Abstract
Exercise training (ExT) is an established non-pharmacological therapy that improves the health and quality of life in patients with chronic heart failure (CHF). Exaggerated sympathetic drive characterizes CHF due to an imbalance of the autonomic nervous system. Neuronal nitric oxide synthase (nNOS) in the paraventricular nucleus (PVN) produce nitric oxide (NO•), which is known to regulate the sympathetic tone. Previously we have shown that during CHF, the catalytically active dimeric form of nNOS is significantly decreased with a concurrent increase in protein inhibitor of nNOS (PIN) expression, a protein that dissociates dimeric nNOS to monomers and facilitates its degradation. Dimerization of nNOS also requires (6R)-5,6,7,8-tetrahydrobiopterin (BH4) for stability and activity. Previously, we have shown that ExT improves NO-mediated sympathetic inhibition in the PVN; however, the molecular mechanism remains elusive. We hypothesized; ExT restores the sympathetic drive by increasing the levels and catalytically active form of nNOS by abrogating changes in the PIN in the PVN of CHF rats. CHF was induced in adult male Sprague-Dawley rats by coronary artery ligation, which reliably mimics CHF in patients with myocardial infarction. After 4 weeks of surgery, Sham and CHF rats were subjected to 3 weeks of progressive treadmill exercise. ExT significantly (p < 0.05) decreased PIN expression and increased dimer/monomer ratio of nNOS in the PVN of rats with CHF. Moreover, we found decreased GTP cyclohydrolase 1(GCH1) expression: a rate-limiting enzyme for BH4 biosynthesis in the PVN of CHF rats suggesting that perhaps reduced BH4 availability may also contribute to decreased nNOS dimers. Interestingly, CHF induced decrease in GCH1 expression was increased with ExT. Our findings revealed that ExT rectified decreased PIN and GCH1 expression and increased dimer/monomer ratio of nNOS in the PVN, which may lead to increase NO• bioavailability resulting in amelioration of activated sympathetic drive during CHF.
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Affiliation(s)
- Neeru M Sharma
- Department of Cellular and Integrative Physiology, UNMC, Omaha, NE 68198-5850, USA.
| | - Xuefei Liu
- Department of Cellular and Integrative Physiology, UNMC, Omaha, NE 68198-5850, USA
| | - Tamra L Llewellyn
- Department of Cellular and Integrative Physiology, UNMC, Omaha, NE 68198-5850, USA
| | - Kenichi Katsurada
- Department of Cellular and Integrative Physiology, UNMC, Omaha, NE 68198-5850, USA
| | - Kaushik P Patel
- Department of Cellular and Integrative Physiology, UNMC, Omaha, NE 68198-5850, USA
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13
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Tejero J, Hunt AP, Santolini J, Lehnert N, Stuehr DJ. Mechanism and regulation of ferrous heme-nitric oxide (NO) oxidation in NO synthases. J Biol Chem 2019; 294:7904-7916. [PMID: 30926606 DOI: 10.1074/jbc.ra119.007810] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/27/2019] [Indexed: 12/12/2022] Open
Abstract
Nitric oxide (NO) synthases (NOSs) catalyze the formation of NO from l-arginine. We have shown previously that the NOS enzyme catalytic cycle involves a large number of reactions but can be characterized by a global model with three main rate-limiting steps. These are the rate of heme reduction by the flavin domain (kr ), of dissociation of NO from the ferric heme-NO complex (kd ), and of oxidation of the ferrous heme-NO complex (k ox). The reaction of oxygen with the ferrous heme-NO species is part of a futile cycle that does not directly contribute to NO synthesis but allows a population of inactive enzyme molecules to return to the catalytic cycle, and thus, enables a steady-state NO synthesis rate. Previously, we have reported that this reaction does involve the reaction of oxygen with the NO-bound ferrous heme complex, but the mechanistic details of the reaction, that could proceed via either an inner-sphere or an outer-sphere mechanism, remained unclear. Here, we present additional experiments with neuronal NOS (nNOS) and inducible NOS (iNOS) variants (nNOS W409F and iNOS K82A and V346I) and computational methods to study how changes in heme access and electronics affect the reaction. Our results support an inner-sphere mechanism and indicate that the particular heme-thiolate environment of the NOS enzymes can stabilize an N-bound FeIII-N(O)OO- intermediate species and thereby catalyze this reaction, which otherwise is not observed or favorable in proteins like globins that contain a histidine-coordinated heme.
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Affiliation(s)
- Jesús Tejero
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195 and
| | - Andrew P Hunt
- the Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109
| | - Jérôme Santolini
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195 and
| | - Nicolai Lehnert
- the Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109
| | - Dennis J Stuehr
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195 and
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14
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Dikalova AE, Aschner JL, Zhang Y, Kaplowitz MR, Fike CD. Reactive oxygen species modulate Na +-coupled neutral amino acid transporter 1 expression in piglet pulmonary arterial endothelial cells. Am J Physiol Heart Circ Physiol 2019; 316:H911-H919. [PMID: 30794434 DOI: 10.1152/ajpheart.00674.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have previously shown that Na+-coupled neutral amino acid transporter 1 (SNAT1) modulates nitric oxide (NO) production in pulmonary arterial endothelial cells (PAECs) from newborn piglets. Specifically, the ability to increase NO production in response to the l-arginine-NO precursor l-citrulline is dependent on SNAT1 expression. Elucidating factors that regulate SNAT1 expression in PAECs could provide new insights and therapeutic targets relevant to NO production. Our major goals were to determine if reactive oxygen species (ROS) modulate SNAT1 expression in PAECs from newborn piglets and to evaluate the role of NADPH oxidase 1 (NOX1) and uncoupled endothelial NO synthase, enzymatic sources of ROS, in hypoxia-induced increases in SNAT1 expression. Treatment with either H2O2 or xanthine plus xanthine oxidase increased SNAT1 expression in PAECs from newborn piglets cultured under normoxic conditions. Hypoxia-induced increases in SNAT1 expression were inhibited by treatments with the ROS-removing agents catalase and superoxide dismutase, NOX1 siRNA, and the NO synthase inhibitor NG-nitro-l-arginine methyl ester. Both tetrahydropbiopterin (BH4) and l-citrulline, two therapies that decrease ROS by recoupling endothelial NO synthase, reduced the hypoxia-induced increase in SNAT1 expression. BH4 and l-citrulline treatment improved NO production in hypoxic PAECs despite a reduction in SNAT1 expression. In conclusion, SNAT1 expression is modulated by ROS in PAECs from newborn piglets. However, ROS-mediated decreases in SNAT1 expression per se do not implicate a reduction in NO production. Although SNAT1 may be critical to l-citrulline-induced increases in NO production, therapies designed to alter SNAT1 expression may not lead to a concordant change in NO production. NEW & NOTEWORTHY Na+-coupled neutral amino acid transporter 1 (SNAT1) modulates nitric oxide (NO) production in piglet pulmonary arterial endothelial cells. Factors that regulate SNAT1 expression in pulmonary arterial endothelial cells are unclear. Here, we show that ROS-reducing strategies inhibit hypoxia-induced increases in SNAT1 expression. l-Citrulline and tetrahydropbiopterin decrease SNAT1 expression but increase NO production. Although SNAT1 is modulated by ROS, changes in SNAT1 expression may not cause a concordant change in NO production.
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Affiliation(s)
- Anna E Dikalova
- Department of Pediatrics, Vanderbilt University Medical Center , Nashville, Tennessee.,Department of Medicine, Vanderbilt University Medical Center , Nashville, Tennessee
| | - Judy L Aschner
- Department of Pediatrics, Albert Einstein College of Medicine, The Bronx, New York
| | - Yongmei Zhang
- Department of Pediatrics, Vanderbilt University Medical Center , Nashville, Tennessee.,Department of Pediatrics, University of Utah Health , Salt Lake City, Utah
| | - Mark R Kaplowitz
- Department of Pediatrics, Vanderbilt University Medical Center , Nashville, Tennessee.,Department of Pediatrics, University of Utah Health , Salt Lake City, Utah
| | - Candice D Fike
- Department of Pediatrics, Vanderbilt University Medical Center , Nashville, Tennessee.,Department of Pediatrics, University of Utah Health , Salt Lake City, Utah
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15
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Tejero J, Shiva S, Gladwin MT. Sources of Vascular Nitric Oxide and Reactive Oxygen Species and Their Regulation. Physiol Rev 2019; 99:311-379. [PMID: 30379623 DOI: 10.1152/physrev.00036.2017] [Citation(s) in RCA: 280] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Nitric oxide (NO) is a small free radical with critical signaling roles in physiology and pathophysiology. The generation of sufficient NO levels to regulate the resistance of the blood vessels and hence the maintenance of adequate blood flow is critical to the healthy performance of the vasculature. A novel paradigm indicates that classical NO synthesis by dedicated NO synthases is supplemented by nitrite reduction pathways under hypoxia. At the same time, reactive oxygen species (ROS), which include superoxide and hydrogen peroxide, are produced in the vascular system for signaling purposes, as effectors of the immune response, or as byproducts of cellular metabolism. NO and ROS can be generated by distinct enzymes or by the same enzyme through alternate reduction and oxidation processes. The latter oxidoreductase systems include NO synthases, molybdopterin enzymes, and hemoglobins, which can form superoxide by reduction of molecular oxygen or NO by reduction of inorganic nitrite. Enzymatic uncoupling, changes in oxygen tension, and the concentration of coenzymes and reductants can modulate the NO/ROS production from these oxidoreductases and determine the redox balance in health and disease. The dysregulation of the mechanisms involved in the generation of NO and ROS is an important cause of cardiovascular disease and target for therapy. In this review we will present the biology of NO and ROS in the cardiovascular system, with special emphasis on their routes of formation and regulation, as well as the therapeutic challenges and opportunities for the management of NO and ROS in cardiovascular disease.
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Affiliation(s)
- Jesús Tejero
- Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh , Pittsburgh, Pennsylvania ; Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania ; Department of Pharmacology and Chemical Biology, University of Pittsburgh , Pittsburgh, Pennsylvania ; and Department of Medicine, Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Sruti Shiva
- Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh , Pittsburgh, Pennsylvania ; Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania ; Department of Pharmacology and Chemical Biology, University of Pittsburgh , Pittsburgh, Pennsylvania ; and Department of Medicine, Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Mark T Gladwin
- Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh , Pittsburgh, Pennsylvania ; Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania ; Department of Pharmacology and Chemical Biology, University of Pittsburgh , Pittsburgh, Pennsylvania ; and Department of Medicine, Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
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16
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Generation and characterization of functional phosphoserine-incorporated neuronal nitric oxide synthase holoenzyme. J Biol Inorg Chem 2018; 24:1-9. [PMID: 30315355 DOI: 10.1007/s00775-018-1621-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/05/2018] [Indexed: 12/19/2022]
Abstract
Phosphorylation is an important pathway for the regulation of nitric oxide synthase (NOS) at the posttranslational level. However, the molecular underpinnings of NOS regulation by phosphorylations remain unclear to date, mainly because of the problems in making a good amount of active phospho-NOS proteins. Herein, we have established a system in which recombinant rat nNOS holoprotein can be produced with site-specific incorporation of phosphoserine (pSer) at residue 1412, using a specialized bacterial host strain for pSer incorporation. The pSer1412 nNOS protein demonstrates UV-Vis, far-UV CD and fluorescence spectral properties that are identical to those of nNOS overexpressed in other bacterial strains. The protein is also functional, possessing normal NO production and NADPH oxidation activities in the presence of abundant substrate L-Arg. Conversely, the rate of FMN-heme interdomain electron transfer (IET) in pSer1412 nNOS is considerably lower than that of wild-type (wt) nNOS, while the phosphomimetic S1142E mutant possesses similar electron transfer kinetics to that of wt. The successful incorporation and high yield of pSer1412 into rat nNOS and the significant change in the IET kinetics upon the phosphorylation demonstrate a highly useful method for incorporating native phosphorylation sites as a substantial improvement to commonly used phosphomimetics.
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17
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Zhong L, Tran T, Baguley TD, Lee SJ, Henke A, To A, Li S, Yu S, Grieco FA, Roland J, Schultz PG, Eizirik DL, Rogers N, Chartterjee AK, Tremblay MS, Shen W. A novel inhibitor of inducible NOS dimerization protects against cytokine-induced rat beta cell dysfunction. Br J Pharmacol 2018; 175:3470-3485. [PMID: 29888783 PMCID: PMC6086989 DOI: 10.1111/bph.14388] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 05/14/2018] [Accepted: 05/28/2018] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND AND PURPOSE Beta cell apoptosis is a major feature of type 1 diabetes, and pro-inflammatory cytokines are key drivers of the deterioration of beta cell mass through induction of apoptosis. Mitochondrial stress plays a critical role in mediating apoptosis by releasing cytochrome C into the cytoplasm, directly activating caspase-9 and its downstream signalling cascade. We aimed to identify new compounds that protect beta cells from cytokine-induced activation of the intrinsic (mitochondrial) pathway of apoptosis. EXPERIMENTAL APPROACH Diabetogenic media, composed of IL-1β, IFN-γ and high glucose, were used to induce mitochondrial stress in rat insulin-producing INS1E cells, and a high-content image-based screen of small molecule modulators of Casp9 pathway was performed. KEY RESULTS A novel small molecule, ATV399, was identified from a high-content image-based screen for compounds that inhibit cleaved caspase-9 activation and subsequent beta cell apoptosis induced by a combination of IL-1β, IFN-γ and high glucose, which together mimic the pathogenic diabetic milieu. Through medicinal chemistry optimization, potency was markedly improved (6-30 fold), with reduced inhibitory effects on CYP3A4. Improved analogues, such as CAT639, improved beta cell viability and insulin secretion in cytokine-treated rat insulin-producing INS1E cells and primary dispersed islet cells. Mechanistically, CAT639 reduced the production of NO by allosterically inhibiting dimerization of inducible NOS (iNOS) without affecting its mRNA levels. CONCLUSION AND IMPLICATIONS Taken together, these studies demonstrate a successful phenotypic screening campaign resulting in identification of an inhibitor of iNOS dimerization that protects beta cell viability and function through modulation of mitochondrial stress induced by cytokines.
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Affiliation(s)
- Linlin Zhong
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Tuan Tran
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Tyler D Baguley
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Sang Jun Lee
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Adam Henke
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Andrew To
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Sijia Li
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Shan Yu
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Fabio A Grieco
- ULB Center for Diabetes ResearchUniversite´ Libre de Bruxelles (ULB)Brussels1070Belgium
| | - Jason Roland
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | - Peter G Schultz
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
- Department of ChemistryThe Scripps Research InstituteLa JollaCA92037USA
| | - Decio L Eizirik
- ULB Center for Diabetes ResearchUniversite´ Libre de Bruxelles (ULB)Brussels1070Belgium
| | - Nikki Rogers
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
| | | | | | - Weijun Shen
- California Institute for Biomedical Research (Calibr)La JollaCA92037USA
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18
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Li J, Zheng H, Wang W, Miao Y, Sheng Y, Feng C. Role of an isoform-specific residue at the calmodulin-heme (NO synthase) interface in the FMN - heme electron transfer. FEBS Lett 2018; 592:2425-2431. [PMID: 29904908 DOI: 10.1002/1873-3468.13158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/31/2018] [Accepted: 06/05/2018] [Indexed: 12/18/2022]
Abstract
The interface between calmodulin (CaM) and the NO synthase (NOS) heme domain is the least characterized interprotein interface that the NOS isoforms must traverse through during catalysis. Our previous molecular dynamics simulations predicted a salt bridge between K497 in human inducible NOS (iNOS) heme domain and D118(CaM). Herein, the FMN - heme interdomain electron transfer (IET) rate was found to be notably decreased by charge-reversal mutation, while the IET in the iNOS K497D mutant is significantly restored by the CaM D118K mutation. The results of wild-type protein with added synthetic peptides further demonstrate the critical nature of K497 relative to the rest of the peptide sequence in modulating the IET. These data provide definitive evidence supporting the regulatory role of the isoform-specific K497 residue.
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Affiliation(s)
- Jinghui Li
- College of Pharmacy, University of New Mexico, Albuquerque, NM, USA
| | - Huayu Zheng
- College of Pharmacy, University of New Mexico, Albuquerque, NM, USA.,Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, USA
| | - Wei Wang
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, USA
| | - Yubin Miao
- Department of Radiology, School of Medicine, University of Colorado Denver, Aurora, CO, USA
| | - Yinghong Sheng
- Department of Chemistry & Physics, College of Arts & Sciences, Florida Gulf Coast University, Fort Myers, FL, USA
| | - Changjian Feng
- College of Pharmacy, University of New Mexico, Albuquerque, NM, USA.,Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, USA
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19
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Xie X, Zhang Z, Wang X, Luo Z, Lai B, Xiao L, Wang N. Stachydrine protects eNOS uncoupling and ameliorates endothelial dysfunction induced by homocysteine. Mol Med 2018; 24:10. [PMID: 30134790 PMCID: PMC6016886 DOI: 10.1186/s10020-018-0010-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 03/02/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Hyperhomocysteinemia (HHcy) is an independent risk factor for cardiovascular diseases (CVDs). Stachydrine (STA) is an active component in Chinese motherwort Leonurus heterophyllus sweet, which has been widely used for gynecological and cardiovascular disorders. This study is aimed to examine the effects of STA on homocysteine (Hcy)-induced endothelial dysfunction. METHODS The effects of STA on vascular relaxation in rat thoracic aortas (TA), mesenteric arteries (MA) and renal arteries (RA) were measured by using Multi Myograph System. The levels of nitric oxide (NO), tetrahydrobiopterin (BH4) and guanosine 3', 5' cyclic monophosphate (cGMP) were determined. Endothelial nitric oxide synthase (eNOS) dimers and monomers were assayed by using Western blotting. GTP cyclohydrolase 1 (GTPCH1) and dihydrofolate reductase (DHFR) expressions were measured by using quantitative reverse transcriptase-PCR (qRT-PCR) and Western blotting. RESULTS STA effectively blocked Hcy-induced impairment of endothelium-dependent vasorelaxation in rat TA, MA and RA. STA-elicited arterial relaxations were reduced by NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) or the NO-sensitive guanylyl cyclase inhibitor 1H- [1, 2, 4] Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), but not by inducible iNOS inhibitor 1400 W nor the nonselective COX inhibitor indomethacin. Hcy caused eNOS uncoupling and decreases in NO, cGMP and BH4, which were attenuated by STA. Moreover, STA prevented decreases of GTPCH1 and DHFR levels in Hcy-treated BAECs. CONCLUSION We demonstrated that STA effectively reversed the Hcy-induced endothelial dysfunction and prevented eNOS uncoupling by increasing the expression of GTPCH1 and DHFR. These results revealed a novel mechanism by which STA exerts its beneficial vascular effects.
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Affiliation(s)
- Xinya Xie
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, 710061, China
| | - Zihui Zhang
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, 710061, China
| | - Xinfeng Wang
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, 710061, China
| | - Zhenyu Luo
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, 710061, China
| | - Baochang Lai
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, 710061, China
| | - Lei Xiao
- Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, 710061, China.
| | - Nanping Wang
- The Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, 116044, China.
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20
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Uddin MS, Naider F, Becker JM. Dynamic roles for the N-terminus of the yeast G protein-coupled receptor Ste2p. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2058-2067. [PMID: 28754538 DOI: 10.1016/j.bbamem.2017.07.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/13/2017] [Accepted: 07/24/2017] [Indexed: 12/11/2022]
Abstract
The Saccharomyces cerevisiae α-factor receptor Ste2p has been used extensively as a model to understand the molecular mechanism of signal transduction by G protein-coupled receptors (GPCRs). Single and double cysteine mutants of Ste2p were created and served as surrogates to detect intramolecular interactions and dimerization of Ste2p using disulfide cross-linking methodology. When a mutation was introduced into the phylogenetically conserved tyrosine residue at position 26 (Y26C) in the N-terminus of Ste2p, dimerization was increased greatly. The amount of dimer formed by this Y26C mutant was greatly reduced by ligand binding even though the ligand binding site is far removed from the N-terminus; the lowering of the dimer formation was consistent with a conformational change in the N-terminus of the receptor upon activation. Dimerization was decreased by double mutations Y26C/V109C or Y26C/T114C indicating that Y26 is in close proximity to V109 and T114 of extracellular loop 1 in native Ste2p. Combined with earlier studies, these results indicate previously unrecognized roles for the N-terminus of Ste2p, and perhaps of GPCRs in general, and reveal a specific N-terminus residue or region, that is involved in GPCR signaling, intrareceptor interactions, and receptor dimerization.
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Affiliation(s)
- M Seraj Uddin
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Fred Naider
- Department of Chemistry and Macromolecular Assemblies Institute, College of Staten Island, CUNY, New York, New York 10314, United States; Ph.D. Programs in Biochemistry and Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, United States
| | - Jeffrey M Becker
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States.
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21
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Lee M, Rey K, Besler K, Wang C, Choy J. Immunobiology of Nitric Oxide and Regulation of Inducible Nitric Oxide Synthase. Results Probl Cell Differ 2017; 62:181-207. [PMID: 28455710 DOI: 10.1007/978-3-319-54090-0_8] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Nitric oxide (NO) is a bioactive gas that has multiple roles in innate and adaptive immune responses. In macrophages, nitric oxide is produced by inducible nitric oxide synthase upon microbial and cytokine stimulation. It is needed for host defense against pathogens and for immune regulation. This review will summarize the role of NO and iNOS in inflammatory and immune responses and will discuss the regulatory mechanisms that control inducible nitric oxide synthase expression and activity.
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Affiliation(s)
- Martin Lee
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Kevin Rey
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Katrina Besler
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Christine Wang
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Jonathan Choy
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
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22
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Nox2 contributes to hyperinsulinemia-induced redox imbalance and impaired vascular function. Redox Biol 2017; 13:288-300. [PMID: 28600985 PMCID: PMC5466665 DOI: 10.1016/j.redox.2017.06.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/17/2017] [Accepted: 06/01/2017] [Indexed: 12/22/2022] Open
Abstract
Insulin resistance promotes vascular endothelial dysfunction and subsequent development of cardiovascular disease. Previously we found that skeletal muscle arteriolar flow-induced dilation (FID) was reduced following a hyperinsulinemic clamp in healthy adults. Therefore, we hypothesized that hyperinsulinemia, a hallmark of insulin resistance, contributes to microvascular endothelial cell dysfunction via inducing oxidative stress that is mediated by NADPH oxidase (Nox) system. We examined the effect of insulin, at levels that are comparable with human hyperinsulinemia on 1) FID of isolated arterioles from human skeletal muscle tissue in the presence and absence of Nox inhibitors and 2) human adipose microvascular endothelial cell (HAMECs) expression of nitric oxide (NO), endothelial NO synthase (eNOS), and Nox-mediated oxidative stress. In six lean healthy participants (mean age 25.5±1.6 y, BMI 21.8±0.9), reactive oxygen species (ROS) were increased while NO and arteriolar FID were reduced following 60 min of ex vivo insulin incubation. These changes were reversed after co-incubation with the Nox isoform 2 (Nox2) inhibitor, VAS2870. In HAMECs, insulin-induced time-dependent increases in Nox2 expression and P47phox phosphorylation were echoed by elevations of superoxide production. In contrast, phosphorylation of eNOS and expression of superoxide dismutase (SOD2 and SOD3) isoforms showed a biphasic response with an increased expression at earlier time points followed by a steep reduction phase. Insulin induced eNOS uncoupling that was synchronized with a drop of NO and a surge of ROS production. These effects were reversed by Tempol (SOD mimetic), Tetrahydrobiopterin (BH4; eNOS cofactor), and VAS2870. Finally, insulin induced nitrotyrosine formation which was reversed by inhibiting NO or superoxide generation. In conclusions, hyperinsulinemia may reduce FID via inducing Nox2-mediated superoxide production in microvascular endothelial cells which reduce the availability of NO and enhances peroxynitrite formation. Therefore, the Nox2 pathway should be considered as a target for the prevention of oxidative stress-associated endothelial dysfunction during hyperinsulinemia. Hyperinsulinemia impairs FID and induces ROS production in human muscle arterioles. Insulin-induced ROS production in endotelial cells is mediated by NADPH oxidase. Long exposure to high insulin levels reduces eNOS phosphorylation and NO production.
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Sumi-Ichinose C, Suganuma Y, Kano T, Ihira N, Nomura H, Ikemoto K, Hata T, Katoh S, Ichinose H, Kondo K. Sepiapterin reductase gene-disrupted mice suffer from hypertension with fluctuation and bradycardia. Physiol Rep 2017; 5:5/6/e13196. [PMID: 28320892 PMCID: PMC5371564 DOI: 10.14814/phy2.13196] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 02/12/2017] [Accepted: 02/14/2017] [Indexed: 11/24/2022] Open
Abstract
(6R)‐l‐erythro‐5,6,7,8‐Tetrahydrobiopterin (BH4) is an essential cofactor for monoamine and nitric oxide (NO) production. Sepiapterin reductase (SPR) catalyzes the final step in BH4 biosynthesis. We analyzed the cardiovascular function of adult Spr gene‐disrupted (Spr−/−) mice for the first time. After weaning, Spr−/− mice suffered from hypertension with fluctuation and bradycardia, while the monoamine contents in these mice were less than 10% of those in the wild‐type mice as a result of BH4 depletion. Heart rate variability analysis indicated the sympathetic dominant state in Spr−/− mice. The endothelium‐dependent vascular relaxation in response to acetylcholine was significantly impaired in Spr−/− mice after sexual maturation (above 4 months old). Protein amounts of α1 adrenergic receptor and eNOS in the aorta were not altered. Spr−/− mice exhibited hypoglycemia and elevation of plasma renin activity. Our results suggest that the hypertension with fluctuation and bradycardia of Spr−/− mice would be caused by an imbalance of sympathetic and parasympathetic input and impaired nitric oxide production in endothelial cells. We suggest an important role of BH4 and SPR in age‐related hypertension and a possible relationship with the cardiovascular instabilities in autonomic diseases, including Parkinson's disease and spinal cord injury.
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Affiliation(s)
- Chiho Sumi-Ichinose
- Department of Pharmacology, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Yui Suganuma
- Department of Pharmacology, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Taiki Kano
- Department of Pharmacology, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Noriko Ihira
- Department of Pharmacology, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Hiroko Nomura
- Graduate School of Health Science, Fujita Health University, Toyoake, Japan
| | - Kazuhisa Ikemoto
- Department of Pharmacology, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Tadayoshi Hata
- Graduate School of Health Science, Fujita Health University, Toyoake, Japan
| | - Setsuko Katoh
- Department of Dentistry, Meikai University, Sakado, Japan
| | - Hiroshi Ichinose
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Kazunao Kondo
- Department of Pharmacology, School of Medicine, Fujita Health University, Toyoake, Japan
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24
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Oberhuber R, Riede G, Cardini B, Bernhard D, Messner B, Watschinger K, Steger C, Brandacher G, Pratschke J, Golderer G, Werner ER, Maglione M. Impaired Endothelial Nitric Oxide Synthase Homodimer Formation Triggers Development of Transplant Vasculopathy - Insights from a Murine Aortic Transplantation Model. Sci Rep 2016; 6:37917. [PMID: 27883078 PMCID: PMC5121662 DOI: 10.1038/srep37917] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 11/04/2016] [Indexed: 12/17/2022] Open
Abstract
Transplant vasculopathy (TV) represents a major obstacle to long-term graft survival and correlates with severity of ischemia reperfusion injury (IRI). Donor administration of the nitric oxide synthases (NOS) co-factor tetrahydrobiopterin has been shown to prevent IRI. Herein, we analysed whether tetrahydrobiopterin is also involved in TV development. Using a fully allogeneic mismatched (BALB/c to C57BL/6) murine aortic transplantation model grafts subjected to long cold ischemia time developed severe TV with intimal hyperplasia (α-smooth muscle actin positive cells in the neointima) and endothelial activation (increased P-selectin expression). Donor pretreatment with tetrahydrobiopterin significantly minimised these changes resulting in only marginal TV development. Severe TV observed in the non-treated group was associated with increased protein oxidation and increased occurrence of endothelial NOS monomers in the aortic grafts already during graft procurement. Tetrahydrobiopterin supplementation of the donor prevented all these early oxidative changes in the graft. Non-treated allogeneic grafts without cold ischemia time and syngeneic grafts did not develop any TV. We identified early protein oxidation and impaired endothelial NOS homodimer formation as plausible mechanistic explanation for the crucial role of IRI in triggering TV in transplanted aortic grafts. Therefore, targeting endothelial NOS in the donor represents a promising strategy to minimise TV.
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Affiliation(s)
- Rupert Oberhuber
- Centre of Operative Medicine, Department of Visceral, Transplant and Thoracic Surgery, Medical University Innsbruck, Innsbruck, Austria
| | - Gregor Riede
- Centre of Operative Medicine, Department of Visceral, Transplant and Thoracic Surgery, Medical University Innsbruck, Innsbruck, Austria
| | - Benno Cardini
- Centre of Operative Medicine, Department of Visceral, Transplant and Thoracic Surgery, Medical University Innsbruck, Innsbruck, Austria
| | - David Bernhard
- Cardiac Surgery Research Laboratory, University Clinic for Cardiac Surgery, Medical University Innsbruck, Innsbruck, Austria
| | - Barbara Messner
- Cardiac Surgery Research Laboratory, Department of Surgery, Vienna Medical University, Austria
| | - Katrin Watschinger
- Division of Biological Chemistry, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Christina Steger
- Institute of Pathology, Academic Teaching Hospital Feldkirch, Feldkirch, Austria
| | - Gerald Brandacher
- Centre of Operative Medicine, Department of Visceral, Transplant and Thoracic Surgery, Medical University Innsbruck, Innsbruck, Austria
- Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation (VCA) Laboratory, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Johann Pratschke
- Centre of Operative Medicine, Department of Visceral, Transplant and Thoracic Surgery, Medical University Innsbruck, Innsbruck, Austria
- Department of General-, Visceral- and Transplantation Surgery, Charité, Campus Virchow Klinikum, Berlin, Germany
| | - Georg Golderer
- Division of Biological Chemistry, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Ernst R. Werner
- Division of Biological Chemistry, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Manuel Maglione
- Centre of Operative Medicine, Department of Visceral, Transplant and Thoracic Surgery, Medical University Innsbruck, Innsbruck, Austria
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25
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Dikalova A, Aschner JL, Kaplowitz MR, Summar M, Fike CD. Tetrahydrobiopterin oral therapy recouples eNOS and ameliorates chronic hypoxia-induced pulmonary hypertension in newborn pigs. Am J Physiol Lung Cell Mol Physiol 2016; 311:L743-L753. [PMID: 27542807 PMCID: PMC5142125 DOI: 10.1152/ajplung.00238.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/14/2016] [Indexed: 01/21/2023] Open
Abstract
We previously showed that newborn piglets who develop pulmonary hypertension during exposure to chronic hypoxia have diminished pulmonary vascular nitric oxide (NO) production and evidence of endothelial NO synthase (eNOS) uncoupling (Fike CD, Dikalova A, Kaplowitz MR, Cunningham G, Summar M, Aschner JL. Am J Respir Cell Mol Biol 53: 255-264, 2015). Tetrahydrobiopterin (BH4) is a cofactor that promotes eNOS coupling. Current clinical strategies typically invoke initiating treatment after the diagnosis of pulmonary hypertension, rather than prophylactically. The major purpose of this study was to determine whether starting treatment with an oral BH4 compound, sapropterin dihydrochloride (sapropterin), after the onset of pulmonary hypertension would recouple eNOS in the pulmonary vasculature and ameliorate disease progression in chronically hypoxic piglets. Normoxic (control) and hypoxic piglets were studied. Some hypoxic piglets received oral sapropterin starting on day 3 of hypoxia and continued throughout an additional 7 days of hypoxic exposure. Catheters were placed for hemodynamic measurements, and pulmonary arteries were dissected to assess eNOS dimer-to-monomer ratios (a measure of eNOS coupling), NO production, and superoxide (O2·-) generation. Although higher than in normoxic controls, pulmonary vascular resistance was lower in sapropterin-treated hypoxic piglets than in untreated hypoxic piglets. Consistent with eNOS recoupling, eNOS dimer-to-monomer ratios and NO production were greater and O2·- generation was less in pulmonary arteries from sapropterin-treated than untreated hypoxic animals. When started after disease onset, oral sapropterin treatment inhibits chronic hypoxia-induced pulmonary hypertension at least in part by recoupling eNOS in the pulmonary vasculature of newborn piglets. Rescue treatment with sapropterin may be an effective strategy to inhibit further development of pulmonary hypertension in newborn infants suffering from chronic cardiopulmonary conditions associated with episodes of prolonged hypoxia.
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Affiliation(s)
- Anna Dikalova
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Judy L Aschner
- Department of Pediatrics, Albert Einstein College of Medicine and the Children's Hospital at Montefiore, New York, New York
| | - Mark R Kaplowitz
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pediatrics, the University of Utah School of Medicine, Salt Lake City, Utah; and
| | - Marshall Summar
- Division of Genetics and Metabolism, Children's National Medical Center, Washington, District of Columbia
| | - Candice D Fike
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pediatrics, the University of Utah School of Medicine, Salt Lake City, Utah; and
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26
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Protein disulfide isomerase mediates glutathione depletion-induced cytotoxicity. Biochem Biophys Res Commun 2016; 477:495-502. [DOI: 10.1016/j.bbrc.2016.06.066] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 06/14/2016] [Indexed: 12/31/2022]
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27
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ET-1 Stimulates Superoxide Production by eNOS Following Exposure of Vascular Endothelial Cells to Endotoxin. Shock 2016; 46:60-6. [DOI: 10.1097/shk.0000000000000576] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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28
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Candemir E, Kollert L, Weißflog L, Geis M, Müller A, Post AM, O'Leary A, Harro J, Reif A, Freudenberg F. Interaction of NOS1AP with the NOS-I PDZ domain: Implications for schizophrenia-related alterations in dendritic morphology. Eur Neuropsychopharmacol 2016; 26:741-55. [PMID: 26861996 DOI: 10.1016/j.euroneuro.2016.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/23/2015] [Accepted: 01/23/2016] [Indexed: 12/19/2022]
Abstract
Schizophrenia involves morphological brain changes, including changes in synaptic plasticity and altered dendritic development. Amongst the most promising candidate molecules for schizophrenia are neuronal nitric oxide (NO) synthase (NOS-I, also known as nNOS) and its adapter protein NOS1AP (previously named CAPON). However, the precise molecular mechanisms by which NOS-I and NOS1AP affect disease pathology remain to be resolved. Interestingly, overexpression of NOS1AP affects dendritic morphology, possibly through increased association with the NOS-I PDZ domain. To investigate the effect of NOS1AP on dendritic morphology we overexpressed different NOS1AP isoforms, NOS1AP deletion mutants and the aminoterminal 133 amino acids of NOS-I (NOS-IN133) containing an extended PDZ domain. We examined the interaction of the overexpressed constructs with endogenous NOS-I by co-immunoprecipitation and the consequences of increased NOS-I/NOS1AP PDZ interaction in primary cultures of hippocampal and cortical neurons from C57BL/6J mice. Neurons overexpressing NOS1AP isoforms or deletion mutants showed highly altered spine morphology and excessive growth of filopodia-like protrusions. Sholl analysis of immunostained primary cultured neurons revealed that dendritic branching was mildly affected by NOS1AP overexpression. Our results hint towards an involvement of NOS-I/NOS1AP interaction in the regulation of dendritic spine plasticity. As altered dendritic spine development and filopodial outgrowth are important neuropathological features of schizophrenia, our findings may provide insight into part of the molecular mechanisms involved in brain morphology alterations observed in schizophrenia. As the NOS-I/NOS1AP interface can be targeted by small molecules, our findings ultimately might help to develop novel treatment strategies for schizophrenia patients.
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Affiliation(s)
- Esin Candemir
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital of Frankfurt, 60528 Frankfurt am Main, Germany; Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany; Graduate School of Life Sciences, University of Würzburg, 97080 Würzburg, Germany
| | - Leonie Kollert
- Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Lena Weißflog
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital of Frankfurt, 60528 Frankfurt am Main, Germany; Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Maria Geis
- Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Antje Müller
- Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Antonia M Post
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital of Frankfurt, 60528 Frankfurt am Main, Germany; Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Aet O'Leary
- Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany; Division of Neuropsychopharmacology, Department of Psychology, University of Tartu, Ravila 14A, Tartu 50411 Estonia
| | - Jaanus Harro
- Division of Neuropsychopharmacology, Department of Psychology, University of Tartu, Ravila 14A, Tartu 50411 Estonia
| | - Andreas Reif
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital of Frankfurt, 60528 Frankfurt am Main, Germany; Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Florian Freudenberg
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital of Frankfurt, 60528 Frankfurt am Main, Germany; Department of Psychiatry, Psychosomatics, and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany.
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29
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Hashimoto T, Sivakumaran V, Carnicer R, Zhu G, Hahn VS, Bedja D, Recalde A, Duglan D, Channon KM, Casadei B, Kass DA. Tetrahydrobiopterin Protects Against Hypertrophic Heart Disease Independent of Myocardial Nitric Oxide Synthase Coupling. J Am Heart Assoc 2016; 5:e003208. [PMID: 27001967 PMCID: PMC4943286 DOI: 10.1161/jaha.116.003208] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 02/11/2016] [Indexed: 01/09/2023]
Abstract
BACKGROUND Nitric oxide synthase uncoupling occurs under conditions of oxidative stress modifying the enzyme's function so it generates superoxide rather than nitric oxide. Nitric oxide synthase uncoupling occurs with chronic pressure overload, and both are ameliorated by exogenous tetrahydrobiopterin (BH4)-a cofactor required for normal nitric oxide synthase function-supporting a pathophysiological link. Genetically augmenting BH4 synthesis in endothelial cells fails to replicate this benefit, indicating that other cell types dominate the effects of exogenous BH4 administration. We tested whether the primary cellular target of BH4 is the cardiomyocyte or whether other novel mechanisms are invoked. METHODS AND RESULTS Mice with cardiomyocyte-specific overexpression of GTP cyclohydrolase 1 (mGCH1) and wild-type littermates underwent transverse aortic constriction. The mGCH1 mice had markedly increased myocardial BH4 and, unlike wild type, maintained nitric oxide synthase coupling after transverse aortic constriction; however, the transverse aortic constriction-induced abnormalities in cardiac morphology and function were similar in both groups. In contrast, exogenous BH4 supplementation improved transverse aortic constricted hearts in both groups, suppressed multiple inflammatory cytokines, and attenuated infiltration of inflammatory macrophages into the heart early after transverse aortic constriction. CONCLUSIONS BH4 protection against adverse remodeling in hypertrophic cardiac disease is not driven by its prevention of myocardial nitric oxide synthase uncoupling, as presumed previously. Instead, benefits from exogenous BH4 are mediated by a protective effect coupled to suppression of inflammatory pathways and myocardial macrophage infiltration.
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MESH Headings
- Animals
- Anti-Inflammatory Agents/pharmacology
- Biopterins/analogs & derivatives
- Biopterins/pharmacology
- Cardiovascular Agents/pharmacology
- Cytokines/metabolism
- Cytoprotection
- Disease Models, Animal
- GTP Cyclohydrolase/genetics
- GTP Cyclohydrolase/metabolism
- Humans
- Hypertrophy, Left Ventricular/enzymology
- Hypertrophy, Left Ventricular/pathology
- Hypertrophy, Left Ventricular/physiopathology
- Hypertrophy, Left Ventricular/prevention & control
- Inflammation Mediators/metabolism
- Macrophages/drug effects
- Macrophages/metabolism
- Mice, Transgenic
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/pathology
- Nitric Oxide/metabolism
- Nitric Oxide Synthase/metabolism
- Oxidation-Reduction
- Signal Transduction
- Superoxides/metabolism
- Time Factors
- Ventricular Dysfunction, Left/enzymology
- Ventricular Dysfunction, Left/physiopathology
- Ventricular Dysfunction, Left/prevention & control
- Ventricular Function, Left/drug effects
- Ventricular Remodeling/drug effects
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Affiliation(s)
- Toru Hashimoto
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Vidhya Sivakumaran
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD
| | | | - Guangshuo Zhu
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Virginia S Hahn
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Djahida Bedja
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Alice Recalde
- Department of Cardiovascular Medicine, University of Oxford, UK
| | - Drew Duglan
- Department of Cardiovascular Medicine, University of Oxford, UK
| | - Keith M Channon
- Department of Cardiovascular Medicine, University of Oxford, UK
| | - Barbara Casadei
- Department of Cardiovascular Medicine, University of Oxford, UK
| | - David A Kass
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD
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30
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Murat N, Korhan P, Kizer O, Evcim S, Kefi A, Demir Ö, Gidener S, Atabey N, Esen AA. Resveratrol Protects and Restores Endothelium-Dependent Relaxation in Hypercholesterolemic Rabbit Corpus Cavernosum. J Sex Med 2016; 13:12-21. [DOI: 10.1016/j.jsxm.2015.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 11/14/2015] [Indexed: 12/16/2022]
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31
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Chalupsky K, Kračun D, Kanchev I, Bertram K, Görlach A. Folic Acid Promotes Recycling of Tetrahydrobiopterin and Protects Against Hypoxia-Induced Pulmonary Hypertension by Recoupling Endothelial Nitric Oxide Synthase. Antioxid Redox Signal 2015; 23:1076-91. [PMID: 26414244 PMCID: PMC4657514 DOI: 10.1089/ars.2015.6329] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 09/21/2015] [Accepted: 09/21/2015] [Indexed: 01/29/2023]
Abstract
AIMS Nitric oxide (NO) derived from endothelial NO synthase (eNOS) has been implicated in the adaptive response to hypoxia. An imbalance between 5,6,7,8-tetrahydrobiopterin (BH4) and 7,8-dihydrobiopterin (BH2) can result in eNOS uncoupling and the generation of superoxide instead of NO. Dihydrofolate reductase (DHFR) can recycle BH2 to BH4, leading to eNOS recoupling. However, the role of DHFR and eNOS recoupling in the response to hypoxia is not well understood. We hypothesized that increasing the capacity to recycle BH4 from BH2 would improve NO bioavailability as well as pulmonary vascular remodeling (PVR) and right ventricular hypertrophy (RVH) as indicators of pulmonary hypertension (PH) under hypoxic conditions. RESULTS In human pulmonary artery endothelial cells and murine pulmonary arteries exposed to hypoxia, eNOS was uncoupled as indicated by reduced superoxide production in the presence of the nitric oxide synthase inhibitor, L-(G)-nitro-L-arginine methyl ester (L-NAME). Concomitantly, NO levels, BH4 availability, and expression of DHFR were diminished under hypoxia. Application of folic acid (FA) restored DHFR levels, NO bioavailability, and BH4 levels under hypoxia. Importantly, FA prevented the development of hypoxia-induced PVR, right ventricular pressure increase, and RVH. INNOVATION FA-induced upregulation of DHFR recouples eNOS under hypoxia by improving BH4 recycling, thus preventing hypoxia-induced PH. CONCLUSION FA might serve as a novel therapeutic option combating PH.
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Affiliation(s)
- Karel Chalupsky
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
| | - Damir Kračun
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
| | - Ivan Kanchev
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
| | - Katharina Bertram
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
| | - Agnes Görlach
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich, Germany
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32
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Neuronal and Endothelial Nitric Oxide Synthases in the Paraventricular Nucleus Modulate Sympathetic Overdrive in Insulin-Resistant Rats. PLoS One 2015; 10:e0140762. [PMID: 26485682 PMCID: PMC4613827 DOI: 10.1371/journal.pone.0140762] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Accepted: 09/30/2015] [Indexed: 11/19/2022] Open
Abstract
A central mechanism participates in sympathetic overdrive during insulin resistance (IR). Nitric oxide synthase (NOS) and nitric oxide (NO) modulate sympathetic nerve activity (SNA) in the paraventricular nucleus (PVN), which influences the autonomic regulation of cardiovascular responses. The aim of this study was to explore whether the NO system in the PVN is involved in the modulation of SNA in fructose-induced IR rats. Control rats received ordinary drinking water, whereas IR rats received 12.5% fructose-containing drinking water for 12 wks to induce IR. Basal SNA was assessed based on the changes in renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) in response to chemicals administered to the PVN. We found an increased plasma norepinephrine level but significantly reduced NO content and neuronal NOS (nNOS) and endothelial NOS (eNOS) protein expression levels in the PVN of IR rats compared to Control rats. No difference in inducible NOS (iNOS) protein expression was observed between the two groups. In anesthetized rats, the microinjection of sodium nitroprusside (SNP), an NO donor, or Nω-nitro-L-arginine methyl ester (L-NAME), a non-selective inhibitor of NOS, into the PVN significantly decreased and increased basal SNA, respectively, in both normal and IR rats, but these responses to SNP and L-NAME in IR rats were smaller than those in normal rats. The administration of selective inhibitors of nNOS or eNOS, but not iNOS, to the PVN significantly increased basal SNA in both groups, but these responses were also smaller in IR rats. Moreover, IR rats exhibited reduced nNOS and eNOS activity in the PVN. In conclusion, these data indicate that the decreased protein expression and activity levels of nNOS and eNOS in the PVN lead to a reduction in the NO content in the PVN, thereby contributing to a subsequent enhancement in sympathoexcitation during IR.
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33
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Heine CL, Schmidt R, Geckl K, Schrammel A, Gesslbauer B, Schmidt K, Mayer B, Gorren ACF. Selective Irreversible Inhibition of Neuronal and Inducible Nitric-oxide Synthase in the Combined Presence of Hydrogen Sulfide and Nitric Oxide. J Biol Chem 2015; 290:24932-44. [PMID: 26296888 PMCID: PMC4599001 DOI: 10.1074/jbc.m115.660316] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Indexed: 11/06/2022] Open
Abstract
Citrulline formation by both human neuronal nitric-oxide synthase (nNOS) and mouse macrophage inducible NOS was inhibited by the hydrogen sulfide (H2S) donor Na2S with IC50 values of ∼2.4·10−5 and ∼7.9·10−5m, respectively, whereas human endothelial NOS was hardly affected at all. Inhibition of nNOS was not affected by the concentrations of l-arginine (Arg), NADPH, FAD, FMN, tetrahydrobiopterin (BH4), and calmodulin, indicating that H2S does not interfere with substrate or cofactor binding. The IC50 decreased to ∼1.5·10−5m at pH 6.0 and increased to ∼8.3·10−5m at pH 8.0. Preincubation of concentrated nNOS with H2S under turnover conditions decreased activity after dilution by ∼70%, suggesting irreversible inhibition. However, when calmodulin was omitted during preincubation, activity was not affected, suggesting that irreversible inhibition requires both H2S and NO. Likewise, NADPH oxidation was inhibited with an IC50 of ∼1.9·10−5m in the presence of Arg and BH4 but exhibited much higher IC50 values (∼1.0–6.1·10−4m) when Arg and/or BH4 was omitted. Moreover, the relatively weak inhibition of nNOS by Na2S in the absence of Arg and/or BH4 was markedly potentiated by the NO donor 1-(hydroxy-NNO-azoxy)-l-proline, disodium salt (IC50 ∼ 1.3–2.0·10−5m). These results suggest that nNOS and inducible NOS but not endothelial NOS are irreversibly inhibited by H2S/NO at modest concentrations of H2S in a reaction that may allow feedback inhibition of NO production under conditions of excessive NO/H2S formation.
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Affiliation(s)
| | | | - Kerstin Geckl
- From the Departments of Pharmacology and Toxicology and
| | | | - Bernd Gesslbauer
- Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, Karl Franzens University Graz, A-8010 Graz, Austria
| | - Kurt Schmidt
- From the Departments of Pharmacology and Toxicology and
| | - Bernd Mayer
- From the Departments of Pharmacology and Toxicology and
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34
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Bhopale VM, Yang M, Yu K, Thom SR. Factors Associated with Nitric Oxide-mediated β2 Integrin Inhibition of Neutrophils. J Biol Chem 2015; 290:17474-84. [PMID: 26032418 DOI: 10.1074/jbc.m115.651620] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Indexed: 11/06/2022] Open
Abstract
This investigation explored the mechanism for inhibition of β2 integrin adhesion molecules when neutrophils are exposed to nitric oxide ((•)NO). Roles for specific proteins were elucidated using chemical inhibitors, depletion with small inhibitory RNA, and cells from knock-out mice. Optimal inhibition occurs with exposures to a (•)NO flux of ∼ 28 nmol/min for 2 min or more, which sets up an autocatalytic cascade triggered by activating type 2 nitric-oxide synthase (NOS-2) and NADPH oxidase (NOX). Integrin inhibition does not occur with neutrophils exposed to a NOX inhibitor (Nox2ds), a NOS-2 inhibitor (1400 W), or with cells from mice lacking NOS-2 or the gp91(phox) component of NOX. Reactive species cause S-nitrosylation of cytosolic actin that enhances actin polymerization. Protein cross-linking and actin filament formation assays indicate that increased polymerization occurs because of associations involving vasodilator-stimulated phosphoprotein, focal adhesion kinase, and protein-disulfide isomerase in proximity to actin filaments. These effects were inhibited in cells exposed to ultraviolet light which photo-reverses S-nitrosylated cysteine residues and by co-incubations with cytochalasin D. The autocatalytic cycle can be arrested by protein kinase G activated with 8-bromo-cyclic GMP and by a high (•)NO flux (∼ 112 nmol/min) that inactivates NOX.
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Affiliation(s)
- Veena M Bhopale
- From the Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Ming Yang
- From the Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Kevin Yu
- From the Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Stephen R Thom
- From the Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201
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Tang W, Li H, Poulos TL, Silverman RB. Mechanistic studies of inactivation of inducible nitric oxide synthase by amidines. Biochemistry 2015; 54:2530-8. [PMID: 25811913 DOI: 10.1021/acs.biochem.5b00135] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Nitric oxide synthase (NOS) catalyzes the conversion of L-arginine to L-citrulline and nitric oxide. N(5)-(1-Iminoethyl)-L-ornithine (L-NIO), an amidine-containing molecule, is a natural product known to be an inactivator of inducible NOS (iNOS). Because of the presence of the amidine methyl group in place of the guanidine amino group of substrate L-arginine, the active site heme peroxy intermediate sometimes cannot be protonated, thereby preventing its conversion to the heme oxo intermediate; instead, a heme oxygenase-type mechanism occurs, leading to conversion of the heme to biliverdin. This might be a new and general inactivation mechanism for heme-containing enzymes. In the studies described here, we attempted to provide support for amidines as substrates and inactivators of iNOS by the design and synthesis of amidine analogues of L-NIO having groups other than the amidine methyl group. No nitric oxide- or enzyme-catalyzed products could be detected by incubation of these amidines with iNOS. Although none of the L-NIO analogues acted as substrates, they all inhibited iNOS; increased inhibitory potency correlated with decreased substituent size. Computer modeling and molecular dynamics simulations were run on 10 and 11 to rationalize why these compounds do not act as substrates. Unlike the methyl amidine (L-NIO), the other alkyl groups block binding of O2 at the heme iron. Compounds 8, 9, and 11 were inactivators; however, no heme was lost, and no biliverdin was formed. No kinetic isotope effect on inactivation was observed with perdeuterated ethyl 8. A small amount of dimer disruption occurred with these inactivators, although the amount would not account for complete enzyme inactivation. The L-NIO analogues inactivate iNOS by a yet unknown mechanism; however, it is different from that of L-NIO, and the inactivation mechanism previously reported for L-NIO appears to be unique to methyl amidines.
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Affiliation(s)
- Wei Tang
- †Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, and Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Huiying Li
- ‡Departments of Molecular Biology and Biochemistry, Chemistry, and Pharmaceutical Sciences, University of California, Irvine, California 92697-3900, United States
| | - Thomas L Poulos
- ‡Departments of Molecular Biology and Biochemistry, Chemistry, and Pharmaceutical Sciences, University of California, Irvine, California 92697-3900, United States
| | - Richard B Silverman
- †Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, and Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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Nagpal L, Panda K. Characterization of calmodulin-free murine inducible nitric-oxide synthase. PLoS One 2015; 10:e0121782. [PMID: 25822458 PMCID: PMC4379030 DOI: 10.1371/journal.pone.0121782] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 02/04/2015] [Indexed: 01/17/2023] Open
Abstract
Nitric-Oxide Synthase (NOS), that produces the biological signal molecule Nitric-Oxide (NO), exists in three different isoforms called, neuronal (nNOS), endothelial (eNOS) and inducible (iNOS). All NOS isoforms require post-translational interaction with the calcium-binding protein, calmodulin (CaM) for manifesting their catalytic activity. However, CaM has been suggested to control the translational assembly of the enzyme as well, particularly in helping its inducible isoform, iNOS assume a stable, heme-replete, dimeric and active form. Expression of recombinant murine iNOS in E.coli in the absence of CaM has been previously shown to give extremely poor yield of the enzyme which was claimed to be absolutely heme-free, devoid of flavins, completely monomeric and catalytically inactive when compared to the heme-replete, active, dimeric iNOS, generated through co-expression with CaM. In contrast, we found that although iNOS expressed without CaM does produce significantly low amounts of the CaM-free enzyme, the iNOS thus produced, is not completely devoid of heme and is neither entirely monomeric nor absolutely bereft of catalytic activity as reported before. In fact, iNOS synthesized in the absence of CaM undergoes compromised heme incorporation resulting in extremely poor dimerization and activity compared to its counterpart co-expressed with CaM. Moreover, such CaM-free iNOS has similar flavin content and reductase activity as iNOS co-expressed with CaM, suggesting that CaM may not be as much required for the functional assembly of the iNOS reductase domain as its oxygenase domain. LC-MS/MS-based peptide mapping of the CaM-free iNOS confirmed that it had the same full-length sequence as the CaM-replete iNOS. Isothermal calorimetric measurements also revealed high affinity for CaM binding in the CaM-free iNOS and thus the possible presence of a CaM-binding domain. Thus CaM is essential but not indispensible for the assembly of iNOS and such CaM-free iNOS may help in elucidating the role of CaM on iNOS catalysis.
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Affiliation(s)
- Latika Nagpal
- Department of Biotechnology & Guha Center for Genetic Engineering & Biotechnology, University of Calcutta, Kolkata, India
| | - Koustubh Panda
- Department of Biotechnology & Guha Center for Genetic Engineering & Biotechnology, University of Calcutta, Kolkata, India
- * E-mail:
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Liu YC, Lee MR, Chen CJ, Lin YC, Ho HC. Purification of Cu/Zn superoxide dismutase from Piper betle leaf and its characterization in the oral cavity. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:2225-2232. [PMID: 25650283 DOI: 10.1021/jf505753d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The aim of this study was to purify protein(s) from Piper betle leaf for identification and further characterization. A functionally unknown protein was purified to apparent homogeneity with a molecular mass of 15.7 kDa and identified as Cu/Zn superoxide dismutase (SOD). The purified SOD appeared to be monomeric and converted to its dimeric form with increased enzymatic activity in betel nut oral extract. This irreversible conversion was mainly induced by slaked lime, resulting from the increase in pH of the oral cavity. Oral extract from chewing areca nut alone also induced SOD dimerization due to the presence of arginine. The enhanced activity of the SOD dimer was responsible for the continuous production of hydrogen peroxide in the oral cavity. Thus, SOD may contribute to oral carcinogenesis through the continuous formation of hydrogen peroxide in the oral cavity, in spite of its protective role against cancer in vivo.
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Affiliation(s)
- Yu-Ching Liu
- Proteomics Core Lab, Department of Medical Research, China Medical University Hospital , No. 2 Yu-De Road, Taichung, 40407, Taiwan R.O.C
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Zhao K, Li S, Wu L, Lai C, Yang G. Hydrogen sulfide represses androgen receptor transactivation by targeting at the second zinc finger module. J Biol Chem 2015; 289:20824-35. [PMID: 24942741 DOI: 10.1074/jbc.m114.559518] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Androgen receptor (AR) signaling is indispensable for the development of prostate cancer from the initial androgen-dependent state to a later aggressive androgen-resistant state. This study examined the role of hydrogen sulfide (H(2)S), a novel gasotransmitter, in the regulation of AR signaling as well as its mediation in androgen-independent cell growth in prostate cancer cells. Here we found that H(2)S inhibits cell proliferation of both androgen-dependent (LNCaP) and antiandrogen-resistant prostate cancer cells (LNCaP-B), with more significance on the latter, which was established by long term treatment of parental LNCaP cells with bicalutamide. The expression of cystathionine γ-lyase (CSE), a major H(2)S producing enzyme in prostate tissue, was reduced in both human prostate cancer tissues and LNCaP-B cells. LNCaP-B cells were resistant to bicalutamide-induced cell growth inhibition, and CSE overexpression could rebuild the sensitivity of LNCaP-B cells to bicalutamide. H(2)S significantly repressed the expression of prostate-specific antigen (PSA) and TMPRSS2, two AR-targeted genes. In addition, H(2)S inhibited AR binding with PSA promoter and androgen-responsive element (ARE) luciferase activity. We further found that AR is post-translationally modified by H(2)S through S-sulfhydration. Mutation of cysteine 611 and cysteine 614 in the second zinc finger module of AR-DNA binding domain diminished the effects of H(2)S on AR S-sulfhydration and AR dimerization. These data suggest that reduced CSE/H2S signaling contributes to antiandrogen-resistant status, and sufficient level of H(2)S is able to inhibit AR transactivation and treat castration-resistant prostate cancer.
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39
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Symmetric dimethylarginine alters endothelial nitric oxide activity in glomerular endothelial cells. Cell Signal 2015; 27:1-5. [DOI: 10.1016/j.cellsig.2014.09.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/02/2014] [Accepted: 09/23/2014] [Indexed: 01/27/2023]
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Mukherjee P, Cinelli MA, Kang S, Silverman RB. Development of nitric oxide synthase inhibitors for neurodegeneration and neuropathic pain. Chem Soc Rev 2014; 43:6814-38. [PMID: 24549364 PMCID: PMC4138306 DOI: 10.1039/c3cs60467e] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Nitric oxide (NO) is an important signaling molecule in the human body, playing a crucial role in cell and neuronal communication, regulation of blood pressure, and in immune activation. However, overproduction of NO by the neuronal isoform of nitric oxide synthase (nNOS) is one of the fundamental causes underlying neurodegenerative disorders and neuropathic pain. Therefore, developing small molecules for selective inhibition of nNOS over related isoforms (eNOS and iNOS) is therapeutically desirable. The aims of this review focus on the regulation and dysregulation of NO signaling, the role of NO in neurodegeneration and pain, the structure and mechanism of nNOS, and the use of this information to design selective inhibitors of this enzyme. Structure-based drug design, the bioavailability and pharmacokinetics of these inhibitors, and extensive target validation through animal studies are addressed.
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Affiliation(s)
- Paramita Mukherjee
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
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Bendall JK, Douglas G, McNeill E, Channon KM, Crabtree MJ. Tetrahydrobiopterin in cardiovascular health and disease. Antioxid Redox Signal 2014; 20:3040-77. [PMID: 24294830 PMCID: PMC4038990 DOI: 10.1089/ars.2013.5566] [Citation(s) in RCA: 164] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 11/01/2013] [Accepted: 12/02/2013] [Indexed: 01/03/2023]
Abstract
Tetrahydrobiopterin (BH4) functions as a cofactor for several important enzyme systems, and considerable evidence implicates BH4 as a key regulator of endothelial nitric oxide synthase (eNOS) in the setting of cardiovascular health and disease. BH4 bioavailability is determined by a balance of enzymatic de novo synthesis and recycling, versus degradation in the setting of oxidative stress. Augmenting vascular BH4 levels by pharmacological supplementation has been shown in experimental studies to enhance NO bioavailability. However, it has become more apparent that the role of BH4 in other enzymatic pathways, including other NOS isoforms and the aromatic amino acid hydroxylases, may have a bearing on important aspects of vascular homeostasis, inflammation, and cardiac function. This article reviews the role of BH4 in cardiovascular development and homeostasis, as well as in pathophysiological processes such as endothelial and vascular dysfunction, atherosclerosis, inflammation, and cardiac hypertrophy. We discuss the therapeutic potential of BH4 in cardiovascular disease states and attempt to address how this modulator of intracellular NO-redox balance may ultimately provide a powerful new treatment for many cardiovascular diseases.
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Affiliation(s)
- Jennifer K Bendall
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford , John Radcliffe Hospital, Oxford, United Kingdom
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42
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Jo‐Watanabe A, Ohse T, Nishimatsu H, Takahashi M, Ikeda Y, Wada T, Shirakawa J, Nagai R, Miyata T, Nagano T, Hirata Y, Inagi R, Nangaku M. Glyoxalase I reduces glycative and oxidative stress and prevents age-related endothelial dysfunction through modulation of endothelial nitric oxide synthase phosphorylation. Aging Cell 2014; 13:519-28. [PMID: 24612481 PMCID: PMC4326886 DOI: 10.1111/acel.12204] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2013] [Indexed: 11/30/2022] Open
Abstract
Endothelial dysfunction is a major contributor to cardiovascular disease (CVD), particularly in elderly people. Studies have demonstrated the role of glycation in endothelial dysfunction in nonphysiological models, but the physiological role of glycation in age-related endothelial dysfunction has been poorly addressed. Here, to investigate how vascular glycation affects age-related endothelial function, we employed rats systemically overexpressing glyoxalase I (GLO1), which detoxifies methylglyoxal (MG), a representative precursor of glycation. Four groups of rats were examined, namely young (13 weeks old), mid-age (53 weeks old) wild-type, and GLO1 transgenic (WT/GLO1 Tg) rats. Age-related acceleration in glycation was attenuated in GLO1 Tg rats, together with lower aortic carboxymethyllysine (CML) and urinary 8-hydroxydeoxyguanosine (8-OHdG) levels. Age-related impairment of endothelium-dependent vasorelaxation was attenuated in GLO1 Tg rats, whereas endothelium-independent vasorelaxation was not different between WT and GLO1 Tg rats. Nitric oxide (NO) production was decreased in mid-age WT rats, but not in mid-age GLO1 Tg rats. Age-related inactivation of endothelial NO synthase (eNOS) due to phosphorylation of eNOS on Thr495 and dephosphorylation on Ser1177 was ameliorated in GLO1 Tg rats. In vitro, MG increased phosphorylation of eNOS (Thr495) in primary human aortic endothelial cells (HAECs), and overexpression of GLO1 decreased glycative stress and phosphorylation of eNOS (Thr495). Together, GLO1 reduced age-related endothelial glycative and oxidative stress, altered phohphorylation of eNOS, and attenuated endothelial dysfunction. As a molecular mechanism, GLO1 lessened inhibitory phosphorylation of eNOS (Thr495) by reducing glycative stress. Our study demonstrates that blunting glycative stress prevents the long-term impact of endothelial dysfunction on vascular aging.
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Affiliation(s)
| | - Takamoto Ohse
- Division of Nephrology and Endocrinology Tokyo Japan
| | | | - Masao Takahashi
- Department of Cardiovascular Medicine the University of Tokyo Graduate School of Medicine Tokyo Japan
| | | | - Takehiko Wada
- Division of Nephrology and Endocrinology Tokyo Japan
| | - Jun‐ichi Shirakawa
- Laboratory of Food and Regulation Biology Department of Bioscience School of Agriculture Tokai University Kumamoto Japan
| | - Ryoji Nagai
- Laboratory of Food and Regulation Biology Department of Bioscience School of Agriculture Tokai University Kumamoto Japan
| | - Toshio Miyata
- Graduate School of Medicine Tohoku University Miyagi Japan
| | - Tetsuo Nagano
- Graduate School of Pharmaceutical Sciences the University of TokyoTokyo Japan
| | | | - Reiko Inagi
- Division of Nephrology and Endocrinology Tokyo Japan
- Chronic Kidney Disease Pathophysiology The University of Tokyo Graduate School of Medicine Tokyo Japan
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Thom SR, Bhopale VM, Yang M. Neutrophils generate microparticles during exposure to inert gases due to cytoskeletal oxidative stress. J Biol Chem 2014; 289:18831-45. [PMID: 24867949 DOI: 10.1074/jbc.m113.543702] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
This investigation was to elucidate the mechanism for microparticle (MP) formation triggered by exposures to high pressure inert gases. Human neutrophils generate MPs at a threshold of ∼186 kilopascals with exposures of 30 min or more. Murine cells are similar, but MP production occurs at a slower rate and continues for ∼4 h, whether or not cells remain under pressure. Neutrophils exposed to elevated gas but not hydrostatic pressure produce MPs according to the potency series: argon ≃ nitrogen > helium. Following a similar pattern, gases activate type-2 nitric-oxide synthase (NOS-2) and NADPH oxidase (NOX). MP production does not occur with neutrophils exposed to a NOX inhibitor (Nox2ds) or a NOS-2 inhibitor (1400W) or with cells from mice lacking NOS-2. Reactive species cause S-nitrosylation of cytosolic actin that enhances actin polymerization. Protein cross-linking and immunoprecipitation studies indicate that increased polymerization occurs because of associations involving vasodilator-stimulated phosphoprotein, focal adhesion kinase, the H(+)/K(+) ATPase β (flippase), the hematopoietic cell multidrug resistance protein ABC transporter (floppase), and protein-disulfide isomerase in proximity to short actin filaments. Using chemical inhibitors or reducing cell concentrations of any of these proteins with small inhibitory RNA abrogates NOS-2 activation, reactive species generation, actin polymerization, and MP production. These effects were also inhibited in cells exposed to UV light, which photoreverses S-nitrosylated cysteine residues and by co-incubations with the antioxidant ebselen or cytochalasin D. The autocatalytic cycle of protein activation is initiated by inert gas-mediated singlet O2 production.
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Affiliation(s)
- Stephen R Thom
- From the Department of Emergency Medicine, University of Maryland, Baltimore, Maryland 21201
| | - Veena M Bhopale
- From the Department of Emergency Medicine, University of Maryland, Baltimore, Maryland 21201
| | - Ming Yang
- From the Department of Emergency Medicine, University of Maryland, Baltimore, Maryland 21201
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Chen X, Mak IT. Mg supplementation protects against ritonavir-mediated endothelial oxidative stress and hepatic eNOS downregulation. Free Radic Biol Med 2014; 69:77-85. [PMID: 24434120 PMCID: PMC3960338 DOI: 10.1016/j.freeradbiomed.2014.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 01/06/2014] [Accepted: 01/07/2014] [Indexed: 02/07/2023]
Abstract
Ritonavir (RTV), a prototypical protease inhibitor currently used as a key component of anti-HIV therapy, is known for its endothelial and hepatic toxicity. The effects of RTV and magnesium supplementation on cultured bovine endothelial cell (EC) and rat hepatic endothelial nitric oxide synthase (eNOS) status were investigated. RTV dose-dependently (5-30 µM) decreased EC viability after 48 h; high Mg (2mM) significantly attenuated the lost viability. ECs incubated with 15 µM RTV for 6 to 24h resulted in two- to fourfold elevation of oxidized glutathione and a 25% loss of total glutathione. At 24h, EC superoxide production due to RTV was detected by dihydroethidium staining and increased 41% when quantified by flow cytometry; altered glutathione status and superoxide levels were both substantially reversed by 2mM Mg. RTV reduced eNOS mRNA (-25% at 24 h) and led to decreased eNOS dimer/monomer ratios; nitric oxide-derived products decreased 40%; both changes were attenuated by Mg supplementation. In male Lewis-Brown Norway rats, RTV administration (75 mg/kg/day, 5 weeks) resulted in an 85% increase in plasma 8-isoprostane and a 23% decrease in hepatic eNOS mRNA; concomitantly, eNOS protein decreased 75%, whereas plasma nitrite level was reduced 48%. Dietary Mg supplementation (sixfold higher than control) prevented the eNOS mRNA decrease along with lowering 8-isoprostane and restored the eNOS protein and plasma nitrite levels comparable to controls. In conclusion, Mg attenuates RTV-mediated EC oxidative eNOS dysfunction and downregulation of hepatic eNOS expression; we suggest that Mg can serve as a beneficial adjunct therapeutic against RTV-mediated eNOS toxicity.
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Affiliation(s)
- Xi Chen
- Department of Biochemistry & Molecular Medicine, The George Washington University Medical Center, Washington, DC 20037, USA
| | - I Tong Mak
- Department of Biochemistry & Molecular Medicine, The George Washington University Medical Center, Washington, DC 20037, USA.
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Heine C, Kolesnik B, Schmidt R, Werner ER, Mayer B, Gorren ACF. Interaction between neuronal nitric-oxide synthase and tetrahydrobiopterin revisited: studies on the nature and mechanism of tight pterin binding. Biochemistry 2014; 53:1284-95. [PMID: 24512289 PMCID: PMC3944803 DOI: 10.1021/bi401307r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 02/10/2014] [Indexed: 01/06/2023]
Abstract
Recombinant neuronal nitric-oxide synthase (nNOS) expressed in baculovirus-infected Sf9 cells contains approximately 1 equiv of tightly bound tetrahydrobiopterin (BH4) per dimer and binds a second equivalent with a dissociation constant in the 10(-7)-10(-6) M range. Less is known about the pterin-binding properties of nNOS originating from expression systems such as Escherichia coli that do not produce BH4. We determined the binding properties of E. coli-expressed nNOS for BH4 and several inhibitory pterins by monitoring their effects on enzyme activity. E. coli-expressed nNOS as isolated was activated by BH4 monophasically with EC50 ≈ 2 × 10(-7) M, demonstrating a lack of tight pterin binding. However, overnight incubation with BH4 resulted in tight binding of one BH4 per dimer, yielding an enzyme that resembled Sf9-expressed nNOS. Tight pterin binding was also induced by preincubation with 4-amino-tetrahydrobiopterin, but not by 7,8-dihydrobiopterin or 4-amino-dihydrobiopterin, suggesting that tight-binding site formation requires preincubation with a fully reduced pteridine. Kinetic experiments showed that tight-binding site formation takes approximately 10 min with 1 μM BH4 (2 min with 1 μM 4-amino-BH4) at 4 °C. Anaerobic preincubation experiments demonstrated that O2 is not involved in the process. Gel electrophoretic studies suggest that tight-binding site formation is accompanied by an increase in the strength of the NOS dimer. We propose that incubation of pterin-free nNOS with BH4 creates one tight pterin-binding site per dimer, leaving the other site unaffected, in a reaction that involves redox chemistry.
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Affiliation(s)
- Christian
L. Heine
- Department
of Pharmacology and Toxicology, Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Bernd Kolesnik
- Department
of Pharmacology and Toxicology, Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Renate Schmidt
- Department
of Pharmacology and Toxicology, Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Ernst R. Werner
- Division
of Biological Chemistry, Biocenter, Innsbruck
Medical University, A-6020, Innsbruck, Austria
| | - Bernd Mayer
- Department
of Pharmacology and Toxicology, Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
| | - Antonius C. F. Gorren
- Department
of Pharmacology and Toxicology, Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, A-8010, Graz, Austria
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Sodium-coupled neutral amino acid transporter 1 (SNAT1) modulates L-citrulline transport and nitric oxide (NO) signaling in piglet pulmonary arterial endothelial cells. PLoS One 2014; 9:e85730. [PMID: 24454923 PMCID: PMC3893279 DOI: 10.1371/journal.pone.0085730] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 11/30/2013] [Indexed: 01/22/2023] Open
Abstract
RATIONALE There is evidence that impairments in nitric oxide (NO) signaling contribute to chronic hypoxia-induced pulmonary hypertension. The L-arginine-NO precursor, L-citrulline, has been shown to ameliorate pulmonary hypertension. Sodium-coupled neutral amino acid transporters (SNATs) are involved in the transport of L-citrulline into pulmonary arterial endothelial cells (PAECs). The functional link between the SNATs, L-citrulline, and NO signaling has not yet been explored. OBJECTIVE We tested the hypothesis that changes in SNAT1 expression and transport function regulate NO production by modulating eNOS coupling in newborn piglet PAECs. METHODS AND RESULTS A silencing RNA (siRNA) technique was used to assess the contribution of SNAT1 to NO production and eNOS coupling (eNOS dimer-to-monomer ratios) in PAECs from newborn piglets cultured under normoxic and hypoxic conditions in the presence and absence of L-citrulline. SNAT1 siRNA reduced basal NO production in normoxic PAECs and prevented L-citrulline-induced elevations in NO production in both normoxic and hypoxic PAECs. SNAT1 siRNA reduced basal eNOS dimer-to-monomer ratios in normoxic PAECs and prevented L-citrulline-induced increases in eNOS dimer-to-monomer ratios in hypoxic PAECs. CONCLUSIONS SNAT1 mediated L-citrulline transport modulates eNOS coupling and thus regulates NO production in hypoxic PAECs from newborn piglets. Strategies that increase SNAT1-mediated transport and supply of L-citrulline may serve as novel therapeutic approaches to enhance NO production in patients with pulmonary vascular disease.
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Benson MA, Batchelor H, Chuaiphichai S, Bailey J, Zhu H, Stuehr DJ, Bhattacharya S, Channon KM, Crabtree MJ. A pivotal role for tryptophan 447 in enzymatic coupling of human endothelial nitric oxide synthase (eNOS): effects on tetrahydrobiopterin-dependent catalysis and eNOS dimerization. J Biol Chem 2013; 288:29836-45. [PMID: 23965989 PMCID: PMC3795282 DOI: 10.1074/jbc.m113.493023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/12/2013] [Indexed: 11/06/2022] Open
Abstract
Tetrahydrobiopterin (BH4) is a required cofactor for the synthesis of NO by NOS. Bioavailability of BH4 is a critical factor in regulating the balance between NO and superoxide production by endothelial NOS (eNOS coupling). Crystal structures of the mouse inducible NOS oxygenase domain reveal a homologous BH4-binding site located in the dimer interface and a conserved tryptophan residue that engages in hydrogen bonding or aromatic stacking interactions with the BH4 ring. The role of this residue in eNOS coupling remains unexplored. We overexpressed human eNOS W447A and W447F mutants in novel cell lines with tetracycline-regulated expression of human GTP cyclohydrolase I, the rate-limiting enzyme in BH4 synthesis, to determine the importance of BH4 and Trp-447 in eNOS uncoupling. NO production was abolished in eNOS-W447A cells and diminished in cells expressing W447F, despite high BH4 levels. eNOS-derived superoxide production was significantly elevated in W447A and W447F versus wild-type eNOS, and this was sufficient to oxidize BH4 to 7,8-dihydrobiopterin. In uncoupled, BH4-deficient cells, the deleterious effects of W447A mutation were greatly exacerbated, resulting in further attenuation of NO and greatly increased superoxide production. eNOS dimerization was attenuated in W447A eNOS cells and further reduced in BH4-deficient cells, as demonstrated using a novel split Renilla luciferase biosensor. Reduction of cellular BH4 levels resulted in a switch from an eNOS dimer to an eNOS monomer. These data reveal a key role for Trp-447 in determining NO versus superoxide production by eNOS, by effects on BH4-dependent catalysis, and by modulating eNOS dimer formation.
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Affiliation(s)
- Matthew A. Benson
- the Nuffield Department of Clinical Medicine, Target Discovery Institute, The Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, United Kingdom, and
| | - Helen Batchelor
- From the British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Surawee Chuaiphichai
- From the British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Jade Bailey
- From the British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Hanneng Zhu
- the Nuffield Department of Clinical Medicine, Target Discovery Institute, The Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, United Kingdom, and
| | - Dennis J. Stuehr
- the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Shoumo Bhattacharya
- From the British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Keith M. Channon
- From the British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Mark J. Crabtree
- From the British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
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Nagpal L, Haque MM, Saha A, Mukherjee N, Ghosh A, Ranu BC, Stuehr DJ, Panda K. Mechanism of inducible nitric-oxide synthase dimerization inhibition by novel pyrimidine imidazoles. J Biol Chem 2013; 288:19685-97. [PMID: 23696643 PMCID: PMC3707674 DOI: 10.1074/jbc.m112.446542] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 05/13/2013] [Indexed: 01/19/2023] Open
Abstract
Overproduction of nitric oxide (NO) by inducible nitric-oxide synthase (iNOS) has been etiologically linked to several inflammatory, immunological, and neurodegenerative diseases. As dimerization of NOS is required for its activity, several dimerization inhibitors, including pyrimidine imidazoles, are being evaluated for therapeutic inhibition of iNOS. However, the precise mechanism of their action is still unclear. Here, we examined the mechanism of iNOS inhibition by a pyrimidine imidazole core compound and its derivative (PID), having low cellular toxicity and high affinity for iNOS, using rapid stopped-flow kinetic, gel filtration, and spectrophotometric analysis. PID bound to iNOS heme to generate an irreversible PID-iNOS monomer complex that could not be converted to active dimers by tetrahydrobiopterin (H4B) and l-arginine (Arg). We utilized the iNOS oxygenase domain (iNOSoxy) and two monomeric mutants whose dimerization could be induced (K82AiNOSoxy) or not induced (D92AiNOSoxy) with H4B to elucidate the kinetics of PID binding to the iNOS monomer and dimer. We observed that the apparent PID affinity for the monomer was 11 times higher than the dimer. PID binding rate was also sensitive to H4B and Arg site occupancy. PID could also interact with nascent iNOS monomers in iNOS-synthesizing RAW cells, to prevent their post-translational dimerization, and it also caused irreversible monomerization of active iNOS dimers thereby accomplishing complete physiological inhibition of iNOS. Thus, our study establishes PID as a versatile iNOS inhibitor and therefore a potential in vivo tool for examining the causal role of iNOS in diseases associated with its overexpression as well as therapeutic control of such diseases.
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Affiliation(s)
- Latika Nagpal
- From the Department of Biotechnology and Guha Center for Genetic Engineering and Biotechnology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, India
| | - Mohammad M. Haque
- the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Amit Saha
- the Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Nirmalya Mukherjee
- the Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Arnab Ghosh
- the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Brindaban C. Ranu
- the Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Dennis J. Stuehr
- the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Koustubh Panda
- From the Department of Biotechnology and Guha Center for Genetic Engineering and Biotechnology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, India
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49
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Sharma NM, Llewellyn TL, Zheng H, Patel KP. Angiotensin II-mediated posttranslational modification of nNOS in the PVN of rats with CHF: role for PIN. Am J Physiol Heart Circ Physiol 2013; 305:H843-55. [PMID: 23832698 DOI: 10.1152/ajpheart.00170.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An increased sympathetic drive is an adverse characteristic in chronic heart failure (CHF). The protein expression of neuronal nitric oxide synthase (nNOS)- and hence nitric oxide (NO)-mediated sympathoinhibition is reduced in the paraventricular nucleus (PVN) of rats with CHF. However, the molecular mechanism(s) of nNOS downregulation remain(s) unclear. The aim of the study was to reveal the underlying molecular mechanism for the downregulation of nNOS in the PVN of CHF rats. Sprague-Dawley rats with CHF (6-8 wk after coronary artery ligation) demonstrated decreased nNOS dimer/monomer ratio (42%), with a concomitant increase in the expression of PIN (a protein inhibitor of nNOS known to dissociate nNOS dimers into monomers) by 47% in the PVN. Similarly, PIN expression is increased in a neuronal cell line (NG108) treated with angiotensin II (ANG II). Furthermore, there is an increased accumulation of high-molecular-weight nNOS-ubiquitin (nNOS-Ub) conjugates in the PVN of CHF rats (29%). ANG II treatment in NG108 cells in the presence of a proteasome inhibitor, lactacystin, also leads to a 69% increase in accumulation of nNOS-Ub conjugates immunoprecipitated by an antiubiquitin antibody. There is an ANG II-driven, PIN-mediated decrease in the dimeric catalytically active nNOS in the PVN, due to ubiquitin-dependent proteolytic degradation in CHF. Our results show a novel intermediary mechanism that leads to decreased levels of active nNOS in the PVN, involved in subsequent reduction in sympathoinhibition during CHF, offering a new target for the treatment of CHF and other cardiovascular diseases.
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Affiliation(s)
- Neeru M Sharma
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
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50
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Fike CD, Dikalova A, Slaughter JC, Kaplowitz MR, Zhang Y, Aschner JL. Reactive oxygen species-reducing strategies improve pulmonary arterial responses to nitric oxide in piglets with chronic hypoxia-induced pulmonary hypertension. Antioxid Redox Signal 2013; 18:1727-38. [PMID: 23244497 PMCID: PMC3619184 DOI: 10.1089/ars.2012.4823] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIMS There are no effective treatments for chronic pulmonary hypertension in infants with cardiopulmonary disorders associated with hypoxia, such as those with chronic lung disease. These patients often have poor or inconsistent pulmonary dilator responses to inhaled nitric oxide (iNO) therapy for unknown reasons. One possible explanation for poor responsiveness to iNO is reduced NO bioavailability caused by interactions between reactive oxygen species (ROS) and NO. Our major aim was to determine if strategies to reduce ROS improve dilator responses to the NO donor, S-nitroso-N-acetyl-penicillamine (SNAP), in resistance pulmonary arteries (PRAs) from a newborn piglet model of chronic pulmonary hypertension. RESULTS The dilation to SNAP was significantly impaired in PRAs from piglets with chronic hypoxia-induced pulmonary hypertension. ROS scavengers, including cell-permeable and impermeable agents to degrade hydrogen peroxide (H(2)O(2)), improved dilation to SNAP in PRAs from chronically hypoxic piglets. Treatment with agents to inhibit nitric oxide synthase and NADPH oxidase, potential enzymatic sources of ROS, also improved dilation to SNAP in PRAs from hypoxic piglets. INNOVATION Our studies are the first to utilize a newborn model of chronic pulmonary hypertension to evaluate the impact of a number of potential therapeutic strategies for ROS removal on responses to exogenous NO in the vessels most relevant to the regulation of pulmonary vascular resistance (PRA). CONCLUSIONS Strategies aimed at reducing ROS merit further evaluation and consideration as therapeutic approaches to improve responses to iNO in infants with chronic pulmonary hypertension.
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Affiliation(s)
- Candice D Fike
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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