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da Silva JF, Polk FD, Martin PE, Thai SH, Savu A, Gonzales M, Kath AM, Gee MT, Pires PW. Sex-specific mechanisms of cerebral microvascular BK Ca dysfunction in a mouse model of Alzheimer's disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.06.543962. [PMID: 37333104 PMCID: PMC10274786 DOI: 10.1101/2023.06.06.543962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
BACKGROUND Cerebral microvascular dysfunction and nitro-oxidative stress are present in patients with Alzheimer's disease (AD) and may contribute to disease progression and severity. Large conductance Ca 2+ -activated K + channels (BK Ca ) play an essential role in vasodilatory responses and maintenance of myogenic tone in resistance arteries. BK Ca impairment can lead to microvascular dysfunction and hemodynamic deficits in the brain. We hypothesized that reduced BK Ca function in cerebral arteries mediates microvascular and neurovascular responses in the 5x-FAD model of AD. METHODS BK Ca activity in the cerebral microcirculation was assessed by patch clamp electrophysiology and pressure myography, in situ Ca 2+ sparks by spinning disk confocal microscopy, hemodynamics by laser speckle contrast imaging. Molecular and biochemical analyses were conducted by affinity-purification assays, qPCR, Western blots and immunofluorescence. RESULTS We observed that pial arteries from 5-6 months-old male and female 5x-FAD mice exhibited a hyper-contractile phenotype than wild-type (WT) littermates, which was linked to lower vascular BK Ca activity and reduced open probability. In males, BK Ca dysfunction is likely a consequence of an observed lower expression of the pore-forming subunit BKα and blunted frequency of Ca 2+ sparks, which are required for BK Ca activity. However, in females, impaired BK Ca function is, in part, a consequence of reversible nitro-oxidative changes in the BK α subunit, which reduces its open probability and regulation of vascular tone. We further show that BK Ca function is involved in neurovascular coupling in mice, and its dysfunction is linked to neurovascular dysfunction in the model. CONCLUSION These data highlight the central role played by BK Ca in cerebral microvascular and neurovascular regulation, as well as sex-dependent mechanisms underlying its dysfunction in a mouse model of AD.
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Singh S, Gyawali YP, Jiang T, Bukowski GS, Zheng H, Zhang H, Owopetu R, Thielges MC, Feng C. Probing calmodulin-NO synthase interactions via site-specific infrared spectroscopy: an introductory investigation. J Biol Inorg Chem 2024; 29:243-250. [PMID: 38580821 DOI: 10.1007/s00775-024-02046-0] [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: 11/03/2023] [Accepted: 01/15/2024] [Indexed: 04/07/2024]
Abstract
Calmodulin (CaM) binds to a linker between the oxygenase and reductase domains of nitric oxide synthase (NOS) to regulate the functional conformational dynamics. Specific residues on the interdomain interface guide the domain-domain docking to facilitate the electron transfer in NOS. Notably, the docking interface between CaM and the heme-containing oxygenase domain of NOS is isoform specific, which is only beginning to be investigated. Toward advancing understanding of the distinct CaM-NOS docking interactions by infrared spectroscopy, we introduced a cyano-group as frequency-resolved vibrational probe into CaM individually and when associated with full-length and a bi-domain oxygenase/FMN construct of the inducible NOS isoform (iNOS). Site-specific, selective labeling with p-cyano-L-phenylalanine (CNF) by amber suppression of CaM bound to the iNOS has been accomplished by protein coexpression due to the instability of recombinant iNOS protein alone. We introduced CNF at residue 108, which is at the putative CaM-heme (NOS) docking interface. CNF was also introduced at residue 29, which is distant from the docking interface. FT IR data show that the 108 site is sensitive to CaM-NOS complex formation, while insensitivity to its association with the iNOS protein or peptide was observed for the 29 site. Moreover, narrowing of the IR bands at residue 108 suggests the C≡N probe experiences a more limited distribution of environments, indicating side chain restriction apparent for the complex with iNOS. This initial work sets the stage for residue-specific characterizations of structural dynamics of the docked states of NOS proteins.
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Affiliation(s)
- Swapnil Singh
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Yadav Prasad Gyawali
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Ting Jiang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Gregory S Bukowski
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Huayu Zheng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Haikun Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Rebecca Owopetu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Megan C Thielges
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA.
| | - Changjian Feng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA.
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
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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: 0] [Impact Index Per Article: 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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Roy R, Wilcox J, Webb AJ, O’Gallagher K. Dysfunctional and Dysregulated Nitric Oxide Synthases in Cardiovascular Disease: Mechanisms and Therapeutic Potential. Int J Mol Sci 2023; 24:15200. [PMID: 37894881 PMCID: PMC10607291 DOI: 10.3390/ijms242015200] [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: 09/13/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 10/29/2023] Open
Abstract
Nitric oxide (NO) plays an important and diverse signalling role in the cardiovascular system, contributing to the regulation of vascular tone, endothelial function, myocardial function, haemostasis, and thrombosis, amongst many other roles. NO is synthesised through the nitric oxide synthase (NOS)-dependent L-arginine-NO pathway, as well as the nitrate-nitrite-NO pathway. The three isoforms of NOS, namely neuronal (NOS1), inducible (NOS2), and endothelial (NOS3), have different localisation and functions in the human body, and are consequently thought to have differing pathophysiological roles. Furthermore, as we continue to develop a deepened understanding of the different roles of NOS isoforms in disease, the possibility of therapeutically modulating NOS activity has emerged. Indeed, impaired (or dysfunctional), as well as overactive (or dysregulated) NOS activity are attractive therapeutic targets in cardiovascular disease. This review aims to describe recent advances in elucidating the physiological role of NOS isoforms within the cardiovascular system, as well as mechanisms of dysfunctional and dysregulated NOS in cardiovascular disease. We then discuss the modulation of NO and NOS activity as a target in the development of novel cardiovascular therapeutics.
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Affiliation(s)
- Roman Roy
- Cardiovascular Department, King’s College Hospital NHS Foundation Trust, London SE5 9RS, UK;
| | - Joshua Wilcox
- Cardiovascular Department, Guy’s and St. Thomas’ NHS Foundation Trust, London SE1 7EH, UK;
| | - Andrew J. Webb
- Department of Clinical Pharmacology, British Heart Foundation Centre, School of Cardiovascular and Metabolic Medicine and Sciences, King’s College London, London SE1 7EH, UK;
| | - Kevin O’Gallagher
- Cardiovascular Department, King’s College Hospital NHS Foundation Trust, London SE5 9RS, UK;
- British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, Faculty of Life Sciences & Medicine, King’s College London, London SE5 9NU, UK
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The Breast Cancer Protooncogenes HER2, BRCA1 and BRCA2 and Their Regulation by the iNOS/NOS2 Axis. Antioxidants (Basel) 2022; 11:antiox11061195. [PMID: 35740092 PMCID: PMC9227079 DOI: 10.3390/antiox11061195] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 06/01/2022] [Accepted: 06/06/2022] [Indexed: 02/04/2023] Open
Abstract
The expression of inducible nitric oxide synthase (iNOS; NOS2) and derived NO in various cancers was reported to exert pro- and anti-tumorigenic effects depending on the levels of expression and the tumor types. In humans, the breast cancer level of iNOS was reported to be overexpressed, to exhibit pro-tumorigenic activities, and to be of prognostic significance. Likewise, the expression of the oncogenes HER2, BRCA1, and BRCA2 has been associated with malignancy. The interrelationship between the expression of these protooncogenes and oncogenes and the expression of iNOS is not clear. We have hypothesized that there exist cross-talk signaling pathways between the breast cancer protooncogenes, the iNOS axis, and iNOS-mediated NO mutations of these protooncogenes into oncogenes. We review the molecular regulation of the expression of the protooncogenes in breast cancer and their interrelationships with iNOS expression and activities. In addition, we discuss the roles of iNOS, HER2, BRCA1/2, and NO metabolism in the pathophysiology of cancer stem cells. Bioinformatic analyses have been performed and have found suggested molecular alterations responsible for breast cancer aggressiveness. These include the association of BRCA1/2 mutations and HER2 amplifications with the dysregulation of the NOS pathway. We propose that future studies should be undertaken to investigate the regulatory mechanisms underlying the expression of iNOS and various breast cancer oncogenes, with the aim of identifying new therapeutic targets for the treatment of breast cancers that are refractory to current treatments.
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Guerra DD, Hurt KJ. Gasotransmitters in pregnancy: from conception to uterine involution. Biol Reprod 2020; 101:4-25. [PMID: 30848786 DOI: 10.1093/biolre/ioz038] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 02/14/2019] [Accepted: 03/06/2019] [Indexed: 12/13/2022] Open
Abstract
Gasotransmitters are endogenous small gaseous messengers exemplified by nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S or sulfide). Gasotransmitters are implicated in myriad physiologic functions including many aspects of reproduction. Our objective was to comprehensively review basic mechanisms and functions of gasotransmitters during pregnancy from conception to uterine involution and highlight future research opportunities. We searched PubMed and Web of Science databases using combinations of keywords nitric oxide, carbon monoxide, sulfide, placenta, uterus, labor, and pregnancy. We included English language publications on human and animal studies from any date through August 2018 and retained basic and translational articles with relevant original findings. All gasotransmitters activate cGMP signaling. NO and sulfide also covalently modify target protein cysteines. Protein kinases and ion channels transduce gasotransmitter signals, and co-expressed gasotransmitters can be synergistic or antagonistic depending on cell type. Gasotransmitters influence tubal transit, placentation, cervical remodeling, and myometrial contractility. NO, CO, and sulfide dilate resistance vessels, suppress inflammation, and relax myometrium to promote uterine quiescence and normal placentation. Cervical remodeling and rupture of fetal membranes coincide with enhanced oxidation and altered gasotransmitter metabolism. Mechanisms mediating cellular and organismal changes in pregnancy due to gasotransmitters are largely unknown. Altered gasotransmitter signaling has been reported for preeclampsia, intrauterine growth restriction, premature rupture of membranes, and preterm labor. However, in most cases specific molecular changes are not yet characterized. Nonclassical signaling pathways and the crosstalk among gasotransmitters are emerging investigation topics.
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Affiliation(s)
- Damian D Guerra
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA
| | - K Joseph Hurt
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA.,Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA
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7
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Chen Z, Haus JM, Chen L, Wu SC, Urao N, Koh TJ, Minshall RD. CCL28-induced CCR10/eNOS interaction in angiogenesis and skin wound healing. FASEB J 2020; 34:5838-5850. [PMID: 32124475 DOI: 10.1096/fj.201902060r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 02/06/2020] [Accepted: 02/20/2020] [Indexed: 12/25/2022]
Abstract
Chemokines and their receptors play important roles in vascular homeostasis, development, and angiogenesis. Little is known regarding the molecular signaling mechanisms activated by CCL28 chemokine via its primary receptor CCR10 in endothelial cells (ECs). Here, we test the hypothesis that CCL28/CCR10 signaling plays an important role in regulating skin wound angiogenesis through endothelial nitric oxide synthase (eNOS)-dependent Src, PI3K, and MAPK signaling. We observed nitric oxide (NO) production in human primary ECs stimulated with exogenous CCL28, which also induced direct binding of CCR10 and eNOS resulting in inhibition of eNOS activity. Knockdown of CCR10 with siRNA lead to reduced eNOS expression and tube formation suggesting the involvement of CCR10 in EC angiogenesis. Based on this interaction, we engineered a myristoylated 7 amino acid CCR10-binding domain (Myr-CBD7) peptide and showed that this can block eNOS interaction with CCR10, but not with calmodulin, resulting in upregulation of eNOS activity. Importantly, topical administration of Myr-CBD7 peptide on mouse dermal wounds not only blocked CCR10-eNOS interaction, but also enhanced expression of eNOS, CD31, and IL-4 with reduction of CCL28 and IL-6 levels associated with improved wound healing. These results point to a potential therapeutic strategy to upregulate NO bioavailability, enhance angiogenesis, and improve wound healing by disrupting CCL28-activated CCR10-eNOS interaction.
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Affiliation(s)
- Zhenlong Chen
- Department of Anesthesiology, University of Illinois at Chicago, Chicago, IL, USA
| | - Jacob M Haus
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, USA
| | - Lin Chen
- Department of Periodontics, University of Illinois at Chicago, Chicago, IL, USA.,Center for Wound Healing and Tissue Regeneration, University of Illinois at Chicago, Chicago, IL, USA
| | - Stephanie C Wu
- Center for Lower Extremity Ambulatory Research (CLEAR), Dr. William M. Scholl College of Podiatric Medicine, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Norifumi Urao
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, USA.,Center for Wound Healing and Tissue Regeneration, University of Illinois at Chicago, Chicago, IL, USA
| | - Timothy J Koh
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, USA.,Center for Wound Healing and Tissue Regeneration, University of Illinois at Chicago, Chicago, IL, USA
| | - Richard D Minshall
- Department of Anesthesiology, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pharmacology, University of Illinois at Chicago, Chicago, IL, USA
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8
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Cinelli MA, Do HT, Miley GP, Silverman RB. Inducible nitric oxide synthase: Regulation, structure, and inhibition. Med Res Rev 2020; 40:158-189. [PMID: 31192483 PMCID: PMC6908786 DOI: 10.1002/med.21599] [Citation(s) in RCA: 352] [Impact Index Per Article: 88.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/14/2019] [Accepted: 05/13/2019] [Indexed: 12/11/2022]
Abstract
A considerable number of human diseases have an inflammatory component, and a key mediator of immune activation and inflammation is inducible nitric oxide synthase (iNOS), which produces nitric oxide (NO) from l-arginine. Overexpressed or dysregulated iNOS has been implicated in numerous pathologies including sepsis, cancer, neurodegeneration, and various types of pain. Extensive knowledge has been accumulated about the roles iNOS plays in different tissues and organs. Additionally, X-ray crystal and cryogenic electron microscopy structures have shed new insights on the structure and regulation of this enzyme. Many potent iNOS inhibitors with high selectivity over related NOS isoforms, neuronal NOS, and endothelial NOS, have been discovered, and these drugs have shown promise in animal models of endotoxemia, inflammatory and neuropathic pain, arthritis, and other disorders. A major issue in iNOS inhibitor development is that promising results in animal studies have not translated to humans; there are no iNOS inhibitors approved for human use. In addition to assay limitations, both the dual modalities of iNOS and NO in disease states (ie, protective vs harmful effects) and the different roles and localizations of NOS isoforms create challenges for therapeutic intervention. This review summarizes the structure, function, and regulation of iNOS, with focus on the development of iNOS inhibitors (historical and recent). A better understanding of iNOS' complex functions is necessary before specific drug candidates can be identified for classical indications such as sepsis, heart failure, and pain; however, newer promising indications for iNOS inhibition, such as depression, neurodegenerative disorders, and epilepsy, have been discovered.
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Affiliation(s)
- Maris A. Cinelli
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- Current address: Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824
| | - Ha T. Do
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- Current address: Mersana Therapeutics, Inc., Cambridge, MA 02139
| | - Galen P. Miley
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Richard B. Silverman
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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Guerby P, Swiader A, Tasta O, Pont F, Rodriguez F, Parant O, Vayssière C, Shibata T, Uchida K, Salvayre R, Negre-Salvayre A. Modification of endothelial nitric oxide synthase by 4-oxo-2(E)-nonenal(ONE) in preeclamptic placentas. Free Radic Biol Med 2019; 141:416-425. [PMID: 31323312 DOI: 10.1016/j.freeradbiomed.2019.07.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/09/2019] [Accepted: 07/15/2019] [Indexed: 01/21/2023]
Abstract
Preeclampsia (PE) is a leading cause of pregnancy complications, affecting 3-7% of pregnant women worldwide. The pathophysiology of preeclampsia involves a redox imbalance, oxidative stress and a reduced nitric oxide (NO) bioavailability. The molecular and cellular mechanisms leading to the dysfunction of the placental endothelial NO synthase (eNOS) are not clarified. This study was designed to investigate whether aldehydes generated by lipid peroxidation products (LPP), may contribute to placental eNOS dysfunction in PE. The analysis of placentas from PE-affected patients and normal pregnancies, showed a significant increase in protein carbonyl content, indicative of oxidative stress-induced protein modification, as shown by the accumulation of acrolein, 4-hydroxynonenal (HNE), and 4-oxo-2(E)-nonenal (ONE) adducts in PE placentas. In contrast, the levels of these LPP-adducts were low in placentas from normal pregnancies. Immunofluorescence and confocal experiments pointed out a colocalization of eNOS with ONE-Lys adducts, whereas eNOS was not modified in normal placentas. LC-MS/MS analysis of recombinant eNOS preincubated with ONE, allowed to identify several ONE-modified Lys-containing peptides, confirming that eNOS may undergo post-translational modification by LPP. The preincubation of HTR-8/SVneo human trophoblasts (HTR8) with ONE, resulted in ONE-Lys modification of eNOS and a reduced generation of NO. ONE inhibited the migration of HTR8 trophoblasts in the wound closure model, and this was partly restored by the NO donor, NOC-18, which confirmed the important role of NO in the invasive potential of trophoblasts. In conclusion, placental eNOS is modified by ONE in PE placentas, which emphasizes the sensitivity of this protein to oxidative stress in the disturbed redox environment of preeclamptic pregnancies.
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Affiliation(s)
- Paul Guerby
- Inserm U-1048, Université de Toulouse, France; Pôle de Gynécologie Obstétrique, Hôpital Paule-de-Viguier, CHU de Toulouse, France
| | | | - Oriane Tasta
- Inserm U-1048, Université de Toulouse, France; Pôle de Gynécologie Obstétrique, Hôpital Paule-de-Viguier, CHU de Toulouse, France
| | | | | | - Olivier Parant
- Pôle de Gynécologie Obstétrique, Hôpital Paule-de-Viguier, CHU de Toulouse, France
| | - Christophe Vayssière
- Pôle de Gynécologie Obstétrique, Hôpital Paule-de-Viguier, CHU de Toulouse, France
| | - Takahiro Shibata
- Graduate School of Bioagricultural Sciences, Nagoya University, Japan
| | - Koji Uchida
- Laboratory of Food Chemistry, University of Tokyo, Japan
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11
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Saini R, Singh S. Inducible nitric oxide synthase: An asset to neutrophils. J Leukoc Biol 2018; 105:49-61. [DOI: 10.1002/jlb.4ru0418-161r] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 08/25/2018] [Accepted: 08/26/2018] [Indexed: 12/12/2022] Open
Affiliation(s)
- Rashmi Saini
- Department of ZoologyGargi CollegeUniversity of Delhi Delhi 11049 India
| | - Sarika Singh
- Toxicology & Experimental MedicineCSIR‐Central Drug Research Institute Lucknow 226031 India
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12
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Sumayao R, Newsholme P, McMorrow T. Inducible nitric oxide synthase inhibitor 1400W increases Na + ,K + -ATPase levels and activity and ameliorates mitochondrial dysfunction in Ctns null kidney proximal tubular epithelial cells. Clin Exp Pharmacol Physiol 2018; 45:1149-1160. [PMID: 29924417 DOI: 10.1111/1440-1681.12998] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 06/02/2018] [Accepted: 06/11/2018] [Indexed: 02/02/2023]
Abstract
Nitric oxide (NO) has been shown to play an important role in renal physiology and pathophysiology partly through its influence on various transport systems in the kidney proximal tubule. The role of NO in kidney dysfunction associated with lysosomal storage disorder, cystinosis, is largely unknown. In the present study, the effects of inducible nitric oxide synthase (iNOS)-specific inhibitor, 1400W, on Na+ ,K+ -ATPase activity and expression, mitochondrial integrity and function, nutrient metabolism, and apoptosis were investigated in Ctns null proximal tubular epithelial cells (PTECs). Ctns null PTECs exhibited an increase in iNOS expression, augmented NO and nitrite/nitrate production, and reduced Na+ ,K+ -ATPase expression and activity. In addition, these cells displayed depolarized mitochondria, reduced adenosine triphosphate content, altered nutrient metabolism, and elevated apoptosis. Treatment of Ctns null PTECs with 1400W abolished these effects which culminated in the mitigation of apoptosis in these cells. These findings indicate that uncontrolled NO production may constitute the upstream event that leads to the molecular and biochemical alterations observed in Ctns null PTECs and may explain, at least in part, the generalized proximal tubular dysfunction associated with cystinosis. Further studies are needed to realize the potential benefits of anti-nitrosative therapies in improving renal function and/or attenuating renal injury in cystinosis.
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Affiliation(s)
- Rodolfo Sumayao
- Chemistry Department, De La Salle University, Manila, Philippines
| | - Philip Newsholme
- School of Biomedical Sciences, Curtin Health Innovation Research Institute (CHIRI), Curtin University, Perth, Western Australia, Australia
| | - Tara McMorrow
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
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13
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Piazza M, Taiakina V, Dieckmann T, Guillemette JG. Structural Consequences of Calmodulin EF Hand Mutations. Biochemistry 2017; 56:944-956. [PMID: 28121131 DOI: 10.1021/acs.biochem.6b01296] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Calmodulin (CaM) is a cytosolic Ca2+-binding protein that serves as a control element for many enzymes. It consists of two globular domains, each containing two EF hand pairs capable of binding Ca2+, joined by a flexible central linker region. CaM is able to bind and activate its target proteins in the Ca2+-replete and Ca2+-deplete forms. To study the Ca2+-dependent/independent properties of binding and activation of target proteins by CaM, CaM constructs with Ca2+-binding disrupting mutations of Asp to Ala at position one of each EF hand have been used. These CaM mutant proteins are deficient in binding Ca2+ in either the N-lobe EF hands (CaM12), C-lobe EF hands (CaM34), or all four EF hands (CaM1234). To investigate potential structural changes these mutations may cause, we performed detailed NMR studies of CaM12, CaM34, and CaM1234 including determining the solution structure of CaM1234. We then investigated if these CaM mutants affected the interaction of CaM with a target protein known to interact with apoCaM by determining the solution structure of CaM34 bound to the iNOS CaM binding domain peptide. The structures provide direct structural evidence of changes that are present in these Ca2+-deficient CaM mutants and show these mutations increase the hydrophobic exposed surface and decrease the electronegative surface potential throughout each lobe of CaM. These Ca2+-deficient CaM mutants may not be a true representation of apoCaM and may not allow for native-like interactions of apoCaM with its target proteins.
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Affiliation(s)
- Michael Piazza
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - Valentina Taiakina
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - Thorsten Dieckmann
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - J Guy Guillemette
- Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
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Piazza M, Dieckmann T, Guillemette JG. Structural Studies of a Complex Between Endothelial Nitric Oxide Synthase and Calmodulin at Physiological Calcium Concentration. Biochemistry 2016; 55:5962-5971. [DOI: 10.1021/acs.biochem.6b00821] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael Piazza
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Thorsten Dieckmann
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - J. Guy Guillemette
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Dolgacheva LP, Turovskaya MV, Dynnik VV, Zinchenko VP, Goncharov NV, Davletov B, Turovsky EA. Angiotensin II activates different calcium signaling pathways in adipocytes. Arch Biochem Biophys 2016; 593:38-49. [PMID: 26850364 DOI: 10.1016/j.abb.2016.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 01/11/2016] [Accepted: 02/01/2016] [Indexed: 12/15/2022]
Abstract
Angiotensin II (Ang II) is an important mammalian neurohormone involved in reninangiotensin system. Ang II is produced both constitutively and locally by RAS systems, including white fat adipocytes. The influence of Ang II on adipocytes is complex, affecting different systems of signal transduction from early Са(2+) responses to cell proliferation and differentiation, triglyceride accumulation, expression of adipokine-encoding genes and adipokine secretion. It is known that white fat adipocytes express all RAS components and Ang II receptors (АТ1 and АТ2). The current work was carried out with the primary white adipocytes culture, and Са(2+) signaling pathways activated by Ang II were investigated using fluorescent microscopy. Са(2+)-oscillations and transient responses of differentiated adipocytes to Ang II were registered in cells with both small and multiple lipid inclusions. Using inhibitory analysis and selective antagonists, we now show that Ang II initiates periodic Са(2+)-oscillations and transient responses by activating АТ1 and АТ2 receptors and involving branched signaling cascades: 1) Ang II → Gq → PLC → IP3 → IP3Rs → Ca(2+) 2) Gβγ → PI3Kγ → PKB 3) PKB → eNOS → NO → PKG 4) CD38 → cADPR → RyRs → Ca(2+) In these cascades, AT1 receptors play the leading role. The results of the present work open a perspective of using Ang II for correction of signal resistance of adipocytes often observed during obesity and type 2 diabetes.
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Affiliation(s)
- Lyudmila P Dolgacheva
- Laboratory of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Maria V Turovskaya
- Laboratory of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Vladimir V Dynnik
- Laboratory of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia; Laboratory of System Biochemistry, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Valery P Zinchenko
- Laboratory of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Nikolay V Goncharov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Bazbek Davletov
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, England, UK
| | - Egor A Turovsky
- Laboratory of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia.
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16
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Wang H, Heilshorn SC. Adaptable hydrogel networks with reversible linkages for tissue engineering. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:3717-36. [PMID: 25989348 PMCID: PMC4528979 DOI: 10.1002/adma.201501558] [Citation(s) in RCA: 410] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 04/18/2015] [Indexed: 05/19/2023]
Abstract
Adaptable hydrogels have recently emerged as a promising platform for three-dimensional (3D) cell encapsulation and culture. In conventional, covalently crosslinked hydrogels, degradation is typically required to allow complex cellular functions to occur, leading to bulk material degradation. In contrast, adaptable hydrogels are formed by reversible crosslinks. Through breaking and re-formation of the reversible linkages, adaptable hydrogels can be locally modified to permit complex cellular functions while maintaining their long-term integrity. In addition, these adaptable materials can have biomimetic viscoelastic properties that make them well suited for several biotechnology and medical applications. In this review, an overview of adaptable-hydrogel design considerations and linkage selections is presented, with a focus on various cell-compatible crosslinking mechanisms that can be exploited to form adaptable hydrogels for tissue engineering.
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Affiliation(s)
- Huiyuan Wang
- Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, USA
| | - Sarah C. Heilshorn
- Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, USA
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Toussaint F, Charbel C, Blanchette A, Ledoux J. CaMKII regulates intracellular Ca²⁺ dynamics in native endothelial cells. Cell Calcium 2015; 58:275-85. [PMID: 26100947 DOI: 10.1016/j.ceca.2015.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 05/15/2015] [Accepted: 06/06/2015] [Indexed: 01/11/2023]
Abstract
Localized endothelial Ca(2+) signalling, such as Ca(2+) pulsars, can modulate the contractile state of the underlying vascular smooth muscle cell through specific endothelial targets. In addition to K(Ca)3.1 as a target, Ca(2+) pulsars, an IP3R-dependent pulsatile Ca(2+) release from the endoplasmic reticulum (ER) could activate a frequency-sensitive Ca(2+)-dependent kinase such as CaMKII. In the absence of extracellular Ca(2+), acetylcholine increased endothelial CaMKII phosphorylation and activation, thereby suggesting CaMKII activation independently of Ca(2+) influx. Herein, a reciprocal relation where CaMKII controls endothelial Ca(2+) dynamics has been investigated in mesenteric arteries. Both CaMKIIα and β isoforms have been identified in endothelial cells and close proximity (<40 nm) suggests their association in heteromultimers. Intracellular Ca(2+) monitoring with high speed confocal microscopy then showed that inhibition of CaMKII with KN-93 significantly increased the population of Ca(2+) pulsars active sites (+89%), suggesting CaMKII as a major regulator of Ca(2+) pulsars in native endothelium. Mechanistic insights were then sought through the elucidation of the impact of CaMKII on ER Ca(2+) store. ER Ca(2+) emptying was accelerated by CaMKII inhibition and ER Ca(2+) content was assessed using ionomycin. Exposure to KN-93 strongly diminished ER Ca(2+) content (-61%) by relieving CaMKII-dependent inhibition of IP3 receptors (IP3R). Moreover, in situ proximity ligation assay suggested CaMKII-IP3R promiscuity, essential condition for a protein-protein interaction. Interestingly, segregation of IP3R within myoendothelial projection (MEP) appears to be isoform-specific. Hence, only IP3R type 1 and type 2 are detected within fenestrations of the internal elastic lamina, sites of MEP, whilst type 3 is absent from these structures. In summary, CaMKII seems to act as a Ca(2+)-sensitive switch of a negative feedback loop regulating endothelial Ca(2+) homeostasis, including Ca(2+) pulsars.
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Affiliation(s)
- Fanny Toussaint
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Physiology, Université de Montréal, Québec, Canada
| | - Chimène Charbel
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Pharmacology, Université de Montréal, Québec, Canada
| | | | - Jonathan Ledoux
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Physiology, Université de Montréal, Québec, Canada; Department of Pharmacology, Université de Montréal, Québec, Canada; Department of Medicine, Université de Montréal, Québec, Canada.
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Piazza M, Guillemette JG, Dieckmann T. Dynamics of nitric oxide synthase-calmodulin interactions at physiological calcium concentrations. Biochemistry 2015; 54:1989-2000. [PMID: 25751535 DOI: 10.1021/bi501353s] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The intracellular Ca²⁺ concentration is an important regulator of many cellular functions. The small acidic protein calmodulin (CaM) serves as a Ca²⁺ sensor and control element for many enzymes. Nitric oxide synthase (NOS) is one of the proteins that is activated by CaM and plays a major role in a number of key physiological and pathological processes. Previous studies have shown CaM to act like a switch that causes a conformational change in NOS to allow for the electron transfer between the reductase and oxygenase domains through a process that is thought to be highly dynamic. We have analyzed the structure and dynamics of complexes formed by peptides based on inducible NOS (iNOS) and endothelial NOS (eNOS) with CaM at Ca²⁺ concentrations that mimic the physiological basal (17 and 100 nM) and elevated levels (225 nM) found in mammalian cells using fluorescence techniques and nuclear magnetic resonance spectroscopy. The results show the CaM-NOS complexes have similar structures at physiological and fully saturated Ca²⁺ levels; however, their dynamics are remarkably different. At 225 nM Ca²⁺, the CaM-NOS complexes show overall an increase in backbone dynamics, when compared to the dynamics of the complexes at saturating Ca²⁺ concentrations. Specifically, the N-lobe of CaM in the CaM-iNOS complex displays a lower internal mobility (higher S²) and higher exchange protection compared to those of the CaM-eNOS complex. In contrast, the C-lobe of CaM in the CaM-eNOS complex is less dynamic. These results illustrate that structures of CaM-NOS complexes determined at saturated Ca²⁺ concentrations cannot provide a complete picture because the differences in intramolecular dynamics become visible only at physiological Ca²⁺ levels.
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Affiliation(s)
- Michael Piazza
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - J Guy Guillemette
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Thorsten Dieckmann
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Madariaga-Mazón A, Hernández-Abreu O, Estrada-Soto S, Mata R. Insights on the vasorelaxant mode of action of malbrancheamide. J Pharm Pharmacol 2015; 67:551-8. [DOI: 10.1111/jphp.12346] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/05/2014] [Indexed: 01/25/2023]
Abstract
Abstract
Objectives
This study was conducted to evaluate the vasorelaxant effect of the fungal alkaloids malbrancheamides on pre-contracted rat aorta rings. Also, we explored the probable mode of action using experimental and theoretical docking studies.
Methods
The vasorelaxant effect was assessed on rat aorta rings pre-contracted with noradrenaline (0.1 μm). The mechanism of action was evaluated using different inhibitors of the pathways involved in the vasorelaxation process, such as l-NAME, indomethacin, tetraethylammonium and atropine. The docking analyses were carried out with AutoDock 4.2 software using the crystallized structure of the cyclooxygenase domain of eNOS.
Key findings
Malbrancheamides (1–3) induced a significant vasorelaxant activity in a concentration- and endothelium-intact model in rat aorta rings, and a lesser effect in an endothelium-denuded model. Malbrancheamide-induced vasorelaxation was significantly weakened by pretreatment of endothelium-intact aortic rings with L-NAME (10 μm), indicating a nitrergic relaxant mechanism. Docking analysis predicted that 1–3 could activate eNOS throughout an allosteric fashion at C1 and C2 pockets.
Conclusions
Experimental evidence revealed that malbrancheamides induced both endothelium-independent and endothelium-dependent relaxant effects. According to theoretical studies, it is feasible that the endothelium-independent relaxation exerted by malbrancheamide could be mediated by its calmodulin inhibitory properties throughout an interference with myosin light chain phosphorylation and a positive modulation of eNOS.
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Affiliation(s)
| | | | - Samuel Estrada-Soto
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Cuernavaca, México
| | - Rachel Mata
- Facultad de Química, Universidad Nacional Autónoma de México, México, México
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Craps J, Wilvers C, Joris V, De Jongh B, Vanderstraeten J, Lobysheva I, Balligand JL, Sonveaux P, Gilon P, Many MC, Gérard AC, Colin IM. Involvement of nitric oxide in iodine deficiency-induced microvascular remodeling in the thyroid gland: role of nitric oxide synthase 3 and ryanodine receptors. Endocrinology 2015; 156:707-20. [PMID: 25406019 DOI: 10.1210/en.2014-1729] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Iodine deficiency (ID) induces microvascular changes in the thyroid gland via a TSH-independent reactive oxygen species-hypoxia inducible factor (HIF)-1α-vascular endothelial growth factor (VEGF) pathway. The involvement of nitric oxide (NO) in this pathway and the role of calcium (Ca(2+)) and of ryanodine receptors (RYRs) in NO synthase 3 (NOS3) activation were investigated in a murine model of goitrogenesis and in 3 in vitro models of ID, including primary cultures of human thyrocytes. ID activated NOS3 and the production of NO in thyrocytes in vitro and increased the thyroid blood flow in vivo. Using bevacizumab (a blocking antibody against VEGF-A) in mice, it appeared that NOS3 is activated upstream of VEGF-A. L-nitroarginine methyl ester (a NOS inhibitor) blocked the ID-induced increase in thyroid blood flow in vivo and NO production in vitro, as well as ID-induced VEGF-A mRNA and HIF-1α expression in vitro, whereas S-nitroso-acetyl-penicillamine (a NO donor) did the opposite. Ca(2+) is involved in this pathway as intracellular Ca(2+) flux increased after ID, and thapsigargin activated NOS3 and increased VEGF-A mRNA expression. Two of the 3 known mammalian RYR isoforms (RYR1 and RYR2) were shown to be expressed in thyrocytes. RYR inhibition using ryanodine at 10μM decreased ID-induced NOS3 activation, HIF-1α, and VEGF-A expression, whereas RYR activation with ryanodine at 1nM increased NOS3 activation and VEGF-A mRNA expression. In conclusion, during the early phase of TSH-independent ID-induced microvascular activation, ID sequentially activates RYRs and NOS3, thereby supporting ID-induced activation of the NO/HIF-1α/VEGF-A pathway in thyrocytes.
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Affiliation(s)
- J Craps
- Pôle de Morphologie (J.C., C.W., B.D.J., J.V., M.-C.M., I.M.C.), de Pharmacologie et Thérapeutique (V.J., I.L., J.-L.B., P.S.), et d'Endocrinologie, Diabète et Nutrition (P.G.), Institut de Recherche Expérimentale et Clinique, Secteur des Sciences de la Santé, Faculté de Médecine, Université catholique de Louvain, 1200, Brussels, Belgium; and Service d'Endocrino-Diabétologie (A.-C.G., I.M.C.), Centre Hospitalier Régional, 7000, Mons-Hainaut, Belgium
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Lerman DA, Prasad S, Alotti N. Calcific Aortic Valve Disease: Molecular Mechanisms and Therapeutic Approaches. Eur Cardiol 2015; 10:108-112. [PMID: 27274771 PMCID: PMC4888946 DOI: 10.15420/ecr.2015.10.2.108] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 10/28/2015] [Indexed: 01/28/2023] Open
Abstract
Calcification occurs in atherosclerotic vascular lesions and In the aortic valve. Calcific aortic valve disease (CAVD) is a slow, progressive disorder that ranges from mild valve thickening without obstruction of blood flow, termed aortic sclerosis, to severe calcification with impaired leaflet motion, termed aortic stenosis. In the past, this process was thought to be 'degenerative' because of time-dependent wear and tear of the leaflets, with passive calcium deposition. The presence of osteoblasts in atherosclerotic vascular lesions and in CAVD implies that calcification is an active, regulated process akin to atherosclerosis, with lipoprotein deposition and chronic inflammation. If calcification is active, via pro-osteogenic pathways, one might expect that development and progression of calcification could be inhibited. The overlap in the clinical factors associated with calcific valve disease and atherosclerosis provides further support for a shared disease mechanism. In our recent research we used an in vitro porcine valve interstitial cell model to study spontaneous calcification and potential promoters and inhibitors. Using this model, we found that denosumab, a human monoclonal antibody targeting the receptor activator of nuclear factor-κB ligand may, at a working concentration of 50 μg/mL, inhibit induced calcium deposition to basal levels.
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Affiliation(s)
- Daniel Alejandro Lerman
- Royal Infirmary Hospital of Edinburgh (NHS Lothian), The University of Edinburgh, United Kingdom
| | - Sai Prasad
- Royal Infirmary Hospital of Edinburgh (NHS Lothian), The University of Edinburgh, United Kingdom
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22
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Abstract
NOSs are homodimeric multidomain enzymes responsible for producing NO. In mammals, NO acts as an intercellular messenger in a variety of signaling reactions, as well as a cytotoxin in the innate immune response. Mammals possess three NOS isoforms--inducible, endothelial, and neuronal NOS--that are composed of an N-terminal oxidase domain and a C-terminal reductase domain. Calmodulin (CaM) activates NO synthesis by binding to the helical region connecting these two domains. Although crystal structures of isolated domains have been reported, no structure is available for full-length NOS. We used high-throughput single-particle EM to obtain the structures and higher-order domain organization of all three NOS holoenzymes. The structures of inducible, endothelial, and neuronal NOS with and without CaM bound are similar, consisting of a dimerized oxidase domain flanked by two separated reductase domains. NOS isoforms adopt many conformations enabled by three flexible linkers. These conformations represent snapshots of the continuous electron transfer pathway from the reductase domain to the oxidase domain, which reveal that only a single reductase domain participates in electron transfer at a time, and that CaM activates NOS by constraining rotational motions and by directly binding to the oxidase domain. Direct visualization of these large conformational changes induced during electron transfer provides significant insight into the molecular underpinnings governing NO formation.
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23
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Ramadoss J, Pastore MB, Magness RR. Endothelial caveolar subcellular domain regulation of endothelial nitric oxide synthase. Clin Exp Pharmacol Physiol 2014; 40:753-64. [PMID: 23745825 DOI: 10.1111/1440-1681.12136] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 05/29/2013] [Accepted: 05/31/2013] [Indexed: 12/12/2022]
Abstract
Complex regulatory processes alter the activity of endothelial nitric oxide synthase (eNOS) leading to nitric oxide (NO) production by endothelial cells under various physiological states. These complex processes require specific subcellular eNOS partitioning between plasma membrane caveolar domains and non-caveolar compartments. Translocation of eNOS from the plasma membrane to intracellular compartments is important for eNOS activation and subsequent NO biosynthesis. We present data reviewing and interpreting information regarding: (i) the coupling of endothelial plasma membrane receptor systems in the caveolar structure relative to eNOS trafficking; (ii) how eNOS trafficking relates to specific protein-protein interactions for inactivation and activation of eNOS; and (iii) how these complex mechanisms confer specific subcellular location relative to eNOS multisite phosphorylation and signalling. Dysfunction in the regulation of eNOS activation may contribute to several disease states, in particular gestational endothelial abnormalities (pre-eclampsia, gestational diabetes etc.), that have life-long deleterious health consequences that predispose the offspring to develop hypertensive disease, Type 2 diabetes and adiposity.
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Affiliation(s)
- Jayanth Ramadoss
- Department of Obstetrics and Gynaecology, University of Texas Medical Branch, Galveston, TX, USA
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Su Y. Regulation of endothelial nitric oxide synthase activity by protein-protein interaction. Curr Pharm Des 2014; 20:3514-20. [PMID: 24180383 PMCID: PMC7039309 DOI: 10.2174/13816128113196660752] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/21/2013] [Indexed: 02/07/2023]
Abstract
Endothelial nitric oxide synthase (eNOS) is expressed in vascular endothelial cells and plays an important role in the regulation of vascular tone, platelet aggregation and angiogenesis. Protein-protein interactions represent an important posttranslational mechanism for eNOS regulation. eNOS has been shown to interact with a variety of regulatory and structural proteins which provide fine tuneup of eNOS activity and eNOS protein trafficking between plasma membrane and intracellular membranes in a number of physiological and pathophysiological processes. eNOS interacts with calmodulin, heat shock protein 90 (Hsp90), dynamin-2, β-actin, tubulin, porin, high-density lipoprotein (HDL) and apolipoprotein AI (ApoAI), resulting in increases in eNOS activity. The negative eNOS interacting proteins include caveolin, G protein-coupled receptors (GPCR), nitric oxide synthase-interacting protein (NOSIP), and nitric oxide synthase trafficking inducer (NOSTRIN). Dynamin-2, NOSIP, NOSTRIN, and cytoskeleton are also involved in eNOS trafficking in endothelial cells. In addition, eNOS associations with cationic amino acid transporter-1 (CAT-1), argininosuccinate synthase (ASS), argininosuccinate lyase (ASL), and soluble guanylate cyclase (sGC) facilitate directed delivery of substrate (L-arginine) to eNOS and optimizing NO production and NO action on its target. Regulation of eNOS by protein-protein interactions would provide potential targets for pharmacological interventions in NO-compromised cardiovascular diseases.
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Affiliation(s)
- Yunchao Su
- Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1120 15th Street, Augusta, GA 30912.
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25
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Calmodulin-induced structural changes in endothelial nitric oxide synthase. FEBS Lett 2012; 587:297-301. [PMID: 23266515 DOI: 10.1016/j.febslet.2012.12.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 12/10/2012] [Accepted: 12/11/2012] [Indexed: 11/21/2022]
Abstract
We have derived structures of intact calmodulin (CaM)-free and CaM-bound endothelial nitric oxide synthase (eNOS) by reconstruction from cryo-electron micrographs. The CaM-free reconstruction is well fitted by the oxygenase domain dimer, but the reductase domains are not visible, suggesting they are mobile and thus delocalized. Additional protein is visible in the CaM-bound reconstruction, concentrated in volumes near two basic patches on each oxygenase domain. One of these corresponds with a presumptive docking site for the reductase domain FMN-binding module. The other is proposed to correspond with a docking site for CaM. A model is suggested in which CaM binding and docking position the reductase domains near the oxygenase domains and promote docking of the FMN-binding modules required for electron transfer.
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26
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Lin SJ, Lu HK, Lee HW, Chen YC, Li CL, Wang LF. Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts. J Periodontal Res 2012; 47:701-10. [PMID: 22533969 DOI: 10.1111/j.1600-0765.2012.01484.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
UNLABELLED Lin S-J, Lu H-K, Lee H-W, Chen Y-C, Li C-L, Wang L-F. Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts. J Periodont Res 2012; 47: 701-710. © 2012 John Wiley & Sons A/S Background and Objective: In our previous study, we found that flutamide [an androgen receptor (AR) antagonist] inhibited the up-regulation of collagen induced by interleukin (IL)-1β and/or nifedipine in gingival fibroblasts. The present study attempted to verify the role of nitric oxide (NO) in the IL-1β/nifedipine-AR pathway in gingival overgrowth. MATERIAL AND METHODS Confluent gingival fibroblasts derived from healthy individuals (n = 4) and those with dihydropyridine-induced gingival overgrowth (DIGO) (n = 6) were stimulated for 48 h with IL-1β (10 ng/mL), nifedipine (0.34 μm) or IL-1β + nifedipine. Gene and protein expression were analyzed with real-time RT-PCR and western blot analyses, respectively. Meanwhile, Sircol dye-binding and the Griess reagent were, respectively, used to detect the concentrations of total soluble collagen and nitrite in the medium. RESULTS IL-1β and nifedipine simultaneously up-regulated the expression of the AR and type-I collagen α1 [Colα1(I)] genes and the total collagen concentration in DIGO cells (p < 0.05). IL-1β strongly increased the expression of inducible nitric oxide synthase (iNOS) mRNA and the nitrite concentration in both healthy and DIGO cells (p < 0.05). However, co-administration of IL-1β and nifedipine largely abrogated the expression of iNOS mRNA and the nitrite concentration with the same treatment. Spearman's correlation coefficients revealed a positive correlation between the AR and total collagen (p < 0.001), but they both showed a negative correlation with iNOS expression and the NO concentration (p < 0.001). The iNOS inhibitor, 1400W, enhanced IL-1β-induced AR expression; furthermore, the NO donor, NONOate, diminished the expression of the AR to a similar extent in gingival fibroblasts derived from both healthy patients and DIGO patients (p < 0.05). CONCLUSION IL-1β-induced NO attenuated AR-mediated collagen production in human gingival fibroblasts. The iNOS/NO system down-regulated the axis of AR/Colα1(I) mRNA expression and the production of AR/total collagen proteins by DIGO cells.
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Affiliation(s)
- S-J Lin
- Shin-Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan Periodontal Department, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan
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Piazza M, Futrega K, Spratt DE, Dieckmann T, Guillemette JG. Structure and dynamics of calmodulin (CaM) bound to nitric oxide synthase peptides: effects of a phosphomimetic CaM mutation. Biochemistry 2012; 51:3651-61. [PMID: 22486744 DOI: 10.1021/bi300327z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitric oxide synthase (NOS) plays a major role in a number of key physiological and pathological processes. Knowledge of how this is regulated is important. The small acidic calcium binding protein, calmodulin (CaM), is required to fully activate the enzyme. The exact mechanism of how CaM activates NOS is not fully understood. Studies have shown CaM to act like a switch that causes a conformational change in NOS to allow for the transfer of an electron between the reductase and oxygenase domains through a process that is thought to be highly dynamic. To investigate the dynamic properties of CaM-NOS interactions, we determined the solution structure of CaM bound to the inducible NOS (iNOS) and endothelial NOS (eNOS) CaM binding region peptides. In addition, we investigated the effect of CaM phosphorylation. Tyrosine 99 (Y99) of CaM is reported to be phosphorylated in vivo. We have produced a phosphomimetic Y99E CaM to investigate the structural and functional effects that the phosphorylation of this residue may have on nitric oxide production. All three mammalian NOS isoforms were included in the investigation. Our results show that a phosphomimetic Y99E CaM significantly reduces the maximal synthase activity of eNOS by 40% while having little effect on nNOS or iNOS activity. A comparative nuclear magnetic resonance study between phosphomimetic Y99E CaM and wild-type CaM bound to the eNOS CaM binding region peptide was performed. This investigation provides important insights into how the increased electronegativity of a phosphorylated CaM protein affects the binding, dynamics, and activation of the NOS enzymes.
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Affiliation(s)
- Michael Piazza
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Abstract
Diabetic nephropathy is the major cause of end-stage renal disease worldwide. Although the renin-angiotensin system has been implicated in the pathogenesis of diabetic nephropathy, angiotensin I-converting enzyme inhibitors have a beneficial effect on diabetic nephropathy independently of their effects on blood pressure and plasma angiotensin II levels. This suggests that the kallikrein-kinin system (KKS) is also involved in the disease. To study the role of the KKS in diabetic nephropathy, mice lacking either the bradykinin B1 receptor (B1R) or the bradykinin B2 receptor (B2R) have been commonly used. However, because absence of either receptor causes enhanced expression of the other, it is difficult to determine the precise functions of each receptor. This difficulty has recently been overcome by comparing mice lacking both receptors with mice lacking each receptor. Deletion of both B1R and B2R reduces nitric oxide (NO) production and aggravates renal diabetic phenotypes, relevant to either lack of B1R or B2R, demonstrating that both B1R and B2R exert protective effects on diabetic nephropathy presumably via NO. Here, we review previous epidemiological and experimental studies, and discuss novel insights regarding the therapeutic implications of the importance of the KKS in averting diabetic nephropathy.
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Wu G, Berka V, Tsai AL. Binding kinetics of calmodulin with target peptides of three nitric oxide synthase isozymes. J Inorg Biochem 2011; 105:1226-37. [PMID: 21763233 DOI: 10.1016/j.jinorgbio.2011.06.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 05/09/2011] [Accepted: 06/15/2011] [Indexed: 11/17/2022]
Abstract
Efficient electron transfer from reductase domain to oxygenase domain in nitric oxide synthase (NOS) is dependent on the binding of calmodulin (CaM). Rate constants for the binding of CaM to NOS target peptides was only determined previously by surface plasmon resonance (SPR) (Biochemistry 35, 8742-8747, 1996) suggesting that the binding of CaM to NOSs is slow and does not support the fast electron transfer in NOSs measured in previous and this studies. To resolve this contradiction, the binding rates of holo Alexa 350 labeled T34C/T110W CaM (Alexa-CaM) to target peptides from three NOS isozymes were determined using fluorescence stopped-flow. All three target peptides exhibited fast k(on) constants at 4.5°C: 6.6×10(8)M(-1)s(-1) for nNOS(726-749), 2.9×10(8)M(-1)s(-1) for eNOS(492-511) and 6.1×10(8)M(-1)s(-1) for iNOS(507-531), 3-4 orders of magnitude faster than those determined previously by SPR. Dissociation rates of NOS target peptides from Alexa-CaM/peptide complexes were measured by Ca(2+) chelation with ETDA: 3.7s(-1) for nNOS(726-749), 4.5s(-1) for eNOS(492-511), and 0.063s(-1) for iNOS(507-531). Our data suggest that the binding of CaM to NOS is fast and kinetically competent for efficient electron transfer and is unlikely rate-limiting in NOS catalysis. Only iNOS(507-531) was able to bind apo Alexa-CaM, but in a very different conformation from its binding to holo Alexa-CaM.
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Affiliation(s)
- Gang Wu
- Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA.
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Ryk C, Wiklund NP, Nyberg T, De Verdier PJ. Ser608Leu polymorphisms in the nitric oxide synthase-2 gene may influence urinary bladder cancer pathogenesis. ACTA ACUST UNITED AC 2011; 45:319-25. [PMID: 21612325 DOI: 10.3109/00365599.2011.584901] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE The aim of this study was to analyse whether the exonic Ser608Leu (rs2297518) polymorphism in nitric oxide synthase-2 (NOS2) influences urinarybladder cancer risk and pathogenesis. MATERIAL AND METHODS Genotyping of 359 bladder cancer patients from a population-based cohort and 164 population controls was carried out by allelic discrimination and sequencing. Genotypes were combined with information on tumour stage, grade, stage progression and cancer-specific death, from a 5-year clinical follow-up. RESULTS For the Ser608Leu polymorphism, TT homozygotes had three-fold higher odds for bladder cancer (p = 0.081), but once ill, a lower risk for stage progression (p = 0.031) and a better prognosis. CONCLUSIONS The data indicate that the Tallele of the NOS2 Ser608Leu polymorphism is an initial risk factor for developing urinary bladder cancer. Among bladder cancer patients, however, individuals who are TT homozygous have a lower risk of developing muscle-invasive disease and a higher cancer-specific survival. Depending on the cellular context, nitric oxide can induce proliferation as well as apoptosis. The results from this and previous studies suggest that NOS2 polymorphisms may influence both the risk of contracting bladder cancer and the aggressiveness of the disease.
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Affiliation(s)
- Charlotta Ryk
- Urology Laboratory, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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Bicuspid aortic valve disease: the role of oxidative stress in Lrp5 bone formation. Cardiovasc Pathol 2011; 20:168-76. [PMID: 21257323 DOI: 10.1016/j.carpath.2010.11.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Revised: 10/22/2010] [Accepted: 11/11/2010] [Indexed: 01/08/2023] Open
Abstract
The bicuspid aortic valve is a common congenital cardiac anomaly, having a prevalence of 0.9% to 1.37% in the general population and a male preponderance ratio of 2:1. The recognition of a bicuspid aortic valve is clinically relevant because of its association with aortic stenosis or regurgitation, aortic aneurysm or dissection, and infective endocarditis. Although some patients with a bicuspid aortic valve may go undetected without clinical complications for a lifetime, the vast majority will require intervention, most often surgery, at some point. In fact, the natural history of bicuspid aortic valve is that of valve calcification and progressive stenosis that typically occur at a faster rate than in tricuspid aortic valves. This pattern of presentation supports the hypothesis that shear stress in patients with congenitally abnormal aortic valves may contribute to an earlier leaflet calcification. However, there is emerging research data showing that the valve calcification process might have a similar pathophysiologic process to that of vascular atherosclerosis. This review focuses on the current knowledge of the cellular mechanisms of bicuspid aortic valve.
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Burggraaf S, Bingham J, Payne J, Kimpton WG, Lowenthal JW, Bean AGD. Increased inducible nitric oxide synthase expression in organs is associated with a higher severity of H5N1 influenza virus infection. PLoS One 2011; 6:e14561. [PMID: 21283521 PMCID: PMC3023712 DOI: 10.1371/journal.pone.0014561] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 12/21/2010] [Indexed: 11/18/2022] Open
Abstract
Background The mechanisms of disease severity caused by H5N1 influenza virus infection remain somewhat unclear. Studies have indicated that a high viral load and an associated hyper inflammatory immune response are influential during the onset of infection. This dysregulated inflammatory response with increased levels of free radicals, such as nitric oxide (NO), appears likely to contribute to disease severity. However, enzymes of the nitric oxide synthase (NOS) family such as the inducible form of NOS (iNOS) generate NO, which serves as a potent anti-viral molecule to combat infection in combination with acute phase proteins and cytokines. Nevertheless, excessive production of iNOS and subsequent high levels of NO during H5N1 infection may have negative effects, acting with other damaging oxidants to promote excessive inflammation or induce apoptosis. Methodology/Principal Findings There are dramatic differences in the severity of disease between chickens and ducks following H5N1 influenza infection. Chickens show a high level of mortality and associated pathology, whilst ducks show relatively minor symptoms. It is not clear how this varying pathogenicty comes about, although it has been suggested that an overactive inflammatory immune response to infection in the chicken, compared to the duck response, may be to blame for the disparity in observed pathology. In this study, we identify and investigate iNOS gene expression in ducks and chickens during H5N1 influenza infection. Infected chickens show a marked increase in iNOS expression in a wide range of organs. Contrastingly, infected duck tissues have lower levels of tissue related iNOS expression. Conclusions/Significance The differences in iNOS expression levels observed between chickens and ducks during H5N1 avian influenza infection may be important in the inflammatory response that contributes to the pathology. Understanding the regulation of iNOS expression and its role during H5N1 influenza infection may provide insights for the development of new therapeutic strategies in the treatment of avian influenza infection.
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Affiliation(s)
- Simon Burggraaf
- Infection and Immunity, CSIRO Australian Animal Health Laboratory, Geelong, Victoria, Australia.
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Datar R, Kaesemeyer WH, Chandra S, Fulton DJ, Caldwell RW. Acute activation of eNOS by statins involves scavenger receptor-B1, G protein subunit Gi, phospholipase C and calcium influx. Br J Pharmacol 2010; 160:1765-72. [PMID: 20649578 DOI: 10.1111/j.1476-5381.2010.00817.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Statins (HMG CoA reductase inhibitors) have beneficial effects independent of reducing cholesterol synthesis and this includes their ability to acutely activate endothelial nitric oxide synthase (eNOS). The mechanism by which this occurs is largely unknown and thus we characterized the pathways by which statins activate NOS, including involvement of scavenger receptor-B1 (SR-B1), which is expressed in endothelial cells and maintains cholesterol concentrations. EXPERIMENTAL APPROACH Nitric oxide production was monitored in bovine aortic endothelial cells (BAECs) exposed to lovastatin (LOV) or pravastatin (PRA) for 10-20 min, alone or following pre-exposure to the end product of HMG-CoA reductase (mevalonate), G protein inhibitors (pertussis/cholera toxins), phospholipase C (PLC) inhibitor (U-73122), or intracellular and extracellular calcium chelators - BAPTA-AM and EGTA (respectively), or a function blocking antibody to SR-B1. KEY RESULTS Both statins increased NO production in a rapid, dose-dependent and HMG-CoA reductase-independent manner. Inhibiting Gi protein or PLC almost completely blocked statin-induced NO generation. Additionally, removing extracellular calcium inhibited statin-induced NO production. COS-7 cells co-transfected with eNOS and SR-B1 increased NO production when exposed to LOV or high-density lipoprotein (HDL), an agonist of SR-B1. These effects were not observed in COS-7 cells with eNOS alone or co-transfected with bradykinin receptor 2, indicating specificity for SR-B1. Further, pretreatment of BAEC with blocking antibody for SR-B1 blocked NO responses to statins and HDL. CONCLUSIONS AND IMPLICATIONS LOV and PRA acutely activate eNOS through pathways that include the cell surface receptor SR-B1, Gi protein, phosholipase C and entry of extracellular calcium into endothelial cells.
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Affiliation(s)
- R Datar
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA 30912, USA
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Xia C, Misra I, Iyanagi T, Kim JJP. Regulation of interdomain interactions by calmodulin in inducible nitric-oxide synthase. J Biol Chem 2009; 284:30708-17. [PMID: 19737939 DOI: 10.1074/jbc.m109.031682] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitric-oxide synthases (NOSs) catalyze the conversion of l-arginine to nitric oxide and citrulline. There are three NOS isozymes, each with a different physiological role: neuronal NOS, endothelial NOS, and inducible NOS (iNOS). NOSs consist of an N-terminal oxygenase domain and a C-terminal reductase domain, linked by a calmodulin (CaM)-binding region. CaM is required for NO production, but unlike other NOS isozymes, iNOS binds CaM independently of the exogenous Ca(2+) concentration. We have co-expressed CaM and the FMN domain of human iNOS, which includes the CaM-binding region. The Ca(2+)-bound protein complex (CaCaMxFMN) forms an air-stable semiquinone when reduced with NADPH and reduces cytochrome c when reconstituted with the iNOS FAD/NADPH domain. We have solved the crystal structure of the CaCaMxFMN complex in four different conformations, each with a different relative orientation, between the FMN domain and the bound CaM. The CaM-binding region together with bound CaM forms a hinge, pivots on the conserved Arg(536), and regulates electron transfer from FAD to FMN and from FMN to heme by adjusting the relative orientation and distance among the three cofactors. In addition, the relative orientations of the N- and C-terminal lobes of CaM are also different among the four conformations, suggesting that the flexibility between the two halves of CaM also contributes to the fine tuning of the orientation/distance between the redox centers. The data demonstrate a possible mode for precise control of electron transfer by altering the distance and orientation of redox centers in a protein displaying domain movement.
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Affiliation(s)
- Chuanwu Xia
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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35
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Li J, Meng Z. The role of sulfur dioxide as an endogenous gaseous vasoactive factor in synergy with nitric oxide. Nitric Oxide 2009; 20:166-74. [DOI: 10.1016/j.niox.2008.12.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2008] [Revised: 10/31/2008] [Accepted: 12/11/2008] [Indexed: 11/16/2022]
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Tran QK, Leonard J, Black DJ, Nadeau OW, Boulatnikov IG, Persechini A. Effects of combined phosphorylation at Ser-617 and Ser-1179 in endothelial nitric-oxide synthase on EC50(Ca2+) values for calmodulin binding and enzyme activation. J Biol Chem 2009; 284:11892-9. [PMID: 19251696 DOI: 10.1074/jbc.m806205200] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have investigated the possible biochemical basis for enhancements in NO production in endothelial cells that have been correlated with agonist- or shear stress-evoked phosphorylation at Ser-1179. We have found that a phosphomimetic substitution at Ser-1179 doubles maximal synthase activity, partially disinhibits cytochrome c reductase activity, and lowers the EC(50)(Ca(2+)) values for calmodulin binding and enzyme activation from the control values of 182 +/- 2 and 422 +/- 22 nm to 116 +/- 2 and 300 +/- 10 nm. These are similar to the effects of a phosphomimetic substitution at Ser-617 (Tran, Q. K., Leonard, J., Black, D. J., and Persechini, A. (2008) Biochemistry 47, 7557-7566). Although combining substitutions at Ser-617 and Ser-1179 has no additional effect on maximal synthase activity, cooperativity between the two substitutions completely disinhibits reductase activity and further reduces the EC(50)(Ca(2+)) values for calmodulin binding and enzyme activation to 77 +/- 2 and 130 +/- 5 nm. We have confirmed that specific Akt-catalyzed phosphorylation of Ser-617 and Ser-1179 and phosphomimetic substitutions at these positions have similar functional effects. Changes in the biochemical properties of eNOS produced by combined phosphorylation at Ser-617 and Ser-1179 are predicted to substantially increase synthase activity in cells at a typical basal free Ca(2+) concentration of 50-100 nm.
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Affiliation(s)
- Quang-Kim Tran
- Division of Molecular Biology and Biochemistry, University of Missouri-Kansas City, Kansas City, Missouri 64110-2499, USA
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37
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Free intracellular Ca2+ regulates bacterial lipopolysaccharide induction of iNOS in human macrophages. Immunobiology 2009; 214:143-52. [DOI: 10.1016/j.imbio.2008.06.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 05/15/2008] [Accepted: 06/06/2008] [Indexed: 11/23/2022]
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Rajamannan NM. Calcific aortic stenosis: lessons learned from experimental and clinical studies. Arterioscler Thromb Vasc Biol 2008; 29:162-8. [PMID: 19023094 DOI: 10.1161/atvbaha.107.156752] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Calcific aortic stenosis is the most common indication for surgical valve replacement in the United States. For years this disease has been described as a passive degenerative process during which serum calcium attaches to the valve surface and binds to the leaflet to form nodules. Therefore, surgical treatment of this disease has been the approach toward relieving outflow obstruction in these patients. Recent studies demonstrate an association between atherosclerosis and its risk factors for aortic valve disease. In 2008, there are increasing number of epidemiology and experimental studies to provide evidence that this disease process is not a passive phenomena. There is an active cellular process that develops within the valve leaflet and causes a regulated bone formation to develop. If the atherosclerotic hypothesis is important in the initiation of aortic stenosis, then treatments used in slowing the progression of atherosclerosis may be effective in patients with aortic valve disease. This review will discuss the pathogenesis and the potential for medical therapy in the management of patients with calcific aortic stenosis by examining the lessons provided from the experimental research.
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Affiliation(s)
- Nalini M Rajamannan
- Division of Cardiology and Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Spratt DE, Taiakina V, Palmer M, Guillemette JG. FRET conformational analysis of calmodulin binding to nitric oxide synthase peptides and enzymes. Biochemistry 2008; 47:12006-17. [PMID: 18947187 DOI: 10.1021/bi801418s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Calmodulin (CaM) is a ubiquitous Ca (2+)-sensor protein that binds and activates the nitric oxide synthase (NOS) enzymes. We have used fluorescence resonance energy transfer (FRET) to examine the conformational transitions of CaM induced by its binding to synthetic nitric oxide synthase (NOS) CaM-binding domain peptides and full length heme-free constitutive NOS (cNOS) enzymes over a range of physiologically relevant free Ca (2+) concentrations. We demonstrate for the first time that the domains of CaM collapse when associated with Ca (2+)-independent inducible NOS CaM-binding domain, similar to the previously solved crystal structures of CaM bound to the Ca (2+)-dependent cNOS peptides. We show that the association of CaM is not detectable with the cNOS peptides at low free Ca (2+) concentrations (<40 nM). In contrast, we demonstrate that CaM associates with the cNOS holo-enzymes in the absence of Ca (2+) and that the Ca (2+)-dependent transition occurs at a lower free Ca (2+) concentration with the cNOS holo-enzymes. Our results suggest that other regions outside of the CaM-binding domain in the cNOS enzymes are involved in the recruitment and binding of CaM. We also demonstrate that CaM binds to the cNOS enzymes in a sequential manner with the Ca (2+)-replete C-lobe binding first followed by the Ca (2+)-replete N-lobe. This novel FRET study helps to clarify some of the observed similarities and differences between the Ca (2+)-dependent/independent interaction between CaM and the NOS isozymes.
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Affiliation(s)
- Donald E Spratt
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Spratt DE, Israel OK, Taiakina V, Guillemette JG. Regulation of mammalian nitric oxide synthases by electrostatic interactions in the linker region of calmodulin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:2065-70. [PMID: 18845278 DOI: 10.1016/j.bbapap.2008.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 08/29/2008] [Accepted: 09/04/2008] [Indexed: 11/29/2022]
Abstract
Calmodulin (CaM), the ubiquitous Ca(2+)-sensing protein, consists of two globular domains separated by a flexible central linker that properly orients CaM's globular domains to bind and regulate various intracellular proteins, including the nitric oxide synthase (NOS) enzymes. In the present study we determined that the charge and length of the central linker of CaM has an effect on the binding and activation of the NOS isozymes by using a variety of charge CaM mutants (T79D, S81D, T79D/S81D, S101D and E84R/E87K) and CaM mutants with residues removed (Delta84, Delta83-84, and Delta81-84). Our kinetic and spectropolarimetry results demonstrate that the NOS enzymes are not adversely affected by the CaM mutants with the exceptions of S101D, E84R/E87K and the deletion of residue 84. Electrostatic interactions in the central linker between residues 82-87 in combination with hydrophobic interactions in the globular domains of CaM are important for its tight association to inducible NOS.
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Affiliation(s)
- Donald E Spratt
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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Tran QK, Leonard J, Black DJ, Persechini A. Phosphorylation within an autoinhibitory domain in endothelial nitric oxide synthase reduces the Ca(2+) concentrations required for calmodulin to bind and activate the enzyme. Biochemistry 2008; 47:7557-66. [PMID: 18558722 DOI: 10.1021/bi8003186] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have investigated the effects of phosphorylation at Ser-617 and Ser-635 within an autoinhibitory domain (residues 595-639) in bovine endothelial nitric oxide synthase on enzyme activity and the Ca (2+) dependencies for calmodulin binding and enzyme activation. A phosphomimetic S617D substitution doubles the maximum calmodulin-dependent enzyme activity and decreases the EC 50(Ca (2+)) values for calmodulin binding and enzyme activation from the wild-type values of 180 +/- 2 and 397 +/- 23 nM to values of 109 +/- 2 and 258 +/- 11 nM, respectively. Deletion of the autoinhibitory domain also doubles the maximum calmodulin-dependent enzyme activity and decreases the EC 50(Ca (2+)) values for calmodulin binding and calmodulin-dependent enzyme activation to 65 +/- 4 and 118 +/- 4 nM, respectively. An S635D substitution has little or no effect on enzyme activity or EC 50(Ca (2+)) values, either alone or when combined with the S617D substitution. These results suggest that phosphorylation at Ser-617 partially reverses suppression by the autoinhibitory domain. Associated effects on the EC 50(Ca (2+)) values and maximum calmodulin-dependent enzyme activity are predicted to contribute equally to phosphorylation-dependent enhancement of NO production during a typical agonist-evoked Ca (2+) transient, while the reduction in EC 50(Ca (2+)) values is predicted to be the major contributor to enhancement at resting free Ca (2+) concentrations.
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Affiliation(s)
- Quang-Kim Tran
- Division of Molecular Biology and Biochemistry, University of Missouri, Kansas City, Missouri 64110-2499, USA
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Topp S, Prasad V, Cianci GC, Weeks ER, Gallivan JP. A genetic toolbox for creating reversible Ca2+-sensitive materials. J Am Chem Soc 2007; 128:13994-5. [PMID: 17061859 DOI: 10.1021/ja064546i] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A major goal of polymer science is to develop "smart" materials that sense specific chemical signals in complex environments and respond with predictable changes in their mechanical properties. Here, we describe a genetic toolbox of natural and engineered protein modules that can be rationally combined in manifold ways to create reversible self-assembling materials that vary in their composition, architecture, and mechanical properties. Using this toolbox, we produced several materials that reversibly self-assemble in the presence of Ca2+ and characterized these materials using particle-tracking microrheology. The properties of these materials could be predicted from the dilute solution behavior of their component modules, suggesting that this toolbox may be generally useful for creating new stimuli-sensitive materials.
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Affiliation(s)
- Shana Topp
- Departments of Chemistry and Physics and the Center for Fundamental and Applied Molecular Evolution, Emory University, 1515 Dickey Drive, Atlanta, GA 30322, USA
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Spratt DE, Taiakina V, Guillemette JG. Calcium-deficient calmodulin binding and activation of neuronal and inducible nitric oxide synthases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:1351-8. [PMID: 17890165 DOI: 10.1016/j.bbapap.2007.07.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 06/25/2007] [Accepted: 07/23/2007] [Indexed: 11/17/2022]
Abstract
The nitric oxide synthase (NOS) enzymes are bound and activated by the Ca(2+)-binding protein, calmodulin (CaM). We have utilized CaM mutants deficient in binding Ca(2+) with mutations in the N-lobe (CaM(12)), the C-lobe (CaM(34)), or both lobes of CaM (CaM(1234)) to determine their effect on the binding and activation of the Ca(2+)-dependent neuronal (nNOS) and Ca(2+)-independent inducible NOS (iNOS) isoforms. Four different kinetic assays were employed to monitor the effect of these CaM mutants on electron transfer rates in NOS. Protein-protein interactions between CaM and NOS were studied using steady-state fluorescence and spectropolarimetry to monitor the binding of these CaM mutants to nNOS and iNOS CaM-binding domain peptides. The CaM mutants were unable to activate nNOS, however, our CD results show that the C-terminal lobe of CaM is capable of binding to nNOS peptide in the presence of Ca(2+). Our results prove for the first time without the use of chelators that apo-CaM is capable of binding to iNOS peptides and holoenzymes.
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Affiliation(s)
- Donald E Spratt
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada
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Li C, Ruan L, Sood SG, Papapetropoulos A, Fulton D, Venema RC. Role of eNOS phosphorylation at Ser-116 in regulation of eNOS activity in endothelial cells. Vascul Pharmacol 2007; 47:257-64. [PMID: 17822962 PMCID: PMC2128865 DOI: 10.1016/j.vph.2007.07.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2007] [Accepted: 07/27/2007] [Indexed: 11/20/2022]
Abstract
Endothelial nitric oxide synthase (eNOS) catalyzes the conversion of L-arginine to L-citrulline and nitric oxide (NO), an important modulator of vascular function. eNOS is regulated post-translationally through phosphorylation/dephosphorylation at a number of specific phosphorylation sites including Ser-116 in the bovine eNOS sequence. Whether phosphorylation of eNOS at Ser-116 in endothelial cells is stimulatory or inhibitory has not previously been definitively determined. In this study we show that mimicking phosphorylation of eNOS at Ser-116 by Asp mutation reduces basal NO release from endothelial cells. Preventing phosphorylation at this site by Ala mutation increases the amount of NO release from endothelial cells in response to agonist stimulation. In addition, mimicking phosphorylation of Ser-116 increases eNOS association with caveolin-1 and reduces the vascular reactivity of intact aortic rings. eNOS phosphorylation at Ser-116, therefore, appears to contribute to negative modulation of eNOS activity and hence to regulation of vascular tone.
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Affiliation(s)
- Chunying Li
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, U.S.A
| | - Ling Ruan
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, U.S.A
| | - Sarika G. Sood
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, U.S.A
| | - Andreas Papapetropoulos
- G.P. Livanos and M. Simou Laboratories, Evangelismos Hospital, Department of Critical Care and Pulmonary Services, University of Athens School of Medicine, Athens, Greece
| | - David Fulton
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, U.S.A
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA 30912, U.S.A
| | - Richard C. Venema
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, U.S.A
- Department of Pediatrics, Medical College of Georgia, Augusta, GA 30912, U.S.A
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA 30912, U.S.A
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45
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Spratt DE, Taiakina V, Palmer M, Guillemette JG. Differential binding of calmodulin domains to constitutive and inducible nitric oxide synthase enzymes. Biochemistry 2007; 46:8288-300. [PMID: 17580957 DOI: 10.1021/bi062130b] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Calmodulin (CaM) is a Ca2+ signal transducing protein that binds and activates many cellular enzymes with physiological relevance, including the mammalian nitric oxide synthase (NOS) isozymes: endothelial NOS (eNOS), neuronal NOS (nNOS), and inducible NOS (iNOS). The mechanism of CaM binding and activation to the iNOS enzyme is poorly understood in part due to the strength of the bound complex and the difficulty of assessing the role played by regions outside of the CaM-binding domain. To further elucidate these processes, we have developed the methodology to investigate CaM binding to the iNOS holoenzyme and generate CaM mutant proteins selectively labeled with fluorescent dyes at specific residues in the N-terminal lobe, C-terminal lobe, or linker region of the protein. In the present study, an iNOS CaM coexpression system allowed for the investigation of CaM binding to the holoenzyme; three different mutant CaM proteins with cysteine substitutions at residues T34 (N-domain), K75 (central linker), and T110 (C-domain) were fluorescently labeled with acrylodan or Alexa Fluor 546 C5-maleimide. These proteins were used to investigate the differential association of each region of CaM with the three NOS isoforms. We have also N-terminally labeled an iNOS CaM-binding domain peptide with dabsyl chloride in order to perform FRET studies between Alexa-labeled residues in the N- and C-terminal domains of CaM to determine CaM's orientation when associated to iNOS. Our FRET results show that CaM binds to the iNOS CaM-binding domain in an antiparallel orientation. Our steady-state fluorescence and circular dichroism studies show that both the N- and C-terminal EF hand pairs of CaM bind to the CaM-binding domain peptide of iNOS in a Ca2+-independent manner; however, only the C-terminal domain showed large Ca2+-dependent conformational changes when associated with the target sequence. Steady-state fluorescence showed that Alexa-labeled CaM proteins are capable of binding to holo-iNOS coexpressed with nCaM, but this complex is a transient species and can be displaced with the addition of excess CaM. Our results show that CaM does not bind to iNOS in a sequential manner as previously proposed for the nNOS enzyme. This investigation provides additional insight into why iNOS remains active even under basal levels of Ca2+ in the cell.
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Affiliation(s)
- Donald E Spratt
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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46
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Derakhshan B, Hao G, Gross SS. Balancing reactivity against selectivity: the evolution of protein S-nitrosylation as an effector of cell signaling by nitric oxide. Cardiovasc Res 2007; 75:210-9. [PMID: 17524376 PMCID: PMC1994943 DOI: 10.1016/j.cardiores.2007.04.023] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2007] [Revised: 04/20/2007] [Accepted: 04/24/2007] [Indexed: 01/22/2023] Open
Abstract
Produced by the action of lightning in the atmosphere of the pre-biotic earth, nitric oxide (NO) is a free radical molecule that provided the major nitrogen source for development of life. Remarkably, when atmospheric sources of NO became restrictive, organisms evolved the capacity for NO biosynthesis and NO took on bioregulatory roles. We now recognize NO as an ancestral regulator of diverse and important biological functions, acting throughout the phylogenetic tree. In mammals, NO has been implicated as a pivotal regulator of virtually every major physiological system. The bioactivities of NO, and reactive species derived from NO, arise predominantly from their covalent addition to proteins. Importantly, S-nitrosylation of protein cysteine (Cys) residues has emerged as a preeminent effector of NO bioactivity. How and why NO selectively adds to particular Cys residues in proteins is poorly understood, yet fundamental to how NO communicates its bioactivities. Also, evolutionary pressures that have shaped S-nitrosylation as a biosignaling modality are obscure. Considering recently recognized NO signaling paradigms, we speculate on the origin of NO signaling in biological systems and the molecular adaptations that have endowed NO with the ability to selectively target a subset of protein Cys residues that mediate biosignaling.
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Affiliation(s)
- Behrad Derakhshan
- Weill Medical College of Cornell University, Department of Pharmacology, 1300 York Avenue, New York, NY 10021, USA
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47
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Long C, Cook LG, Hamilton SL, Wu GY, Mitchell BM. FK506 binding protein 12/12.6 depletion increases endothelial nitric oxide synthase threonine 495 phosphorylation and blood pressure. Hypertension 2007; 49:569-76. [PMID: 17261647 DOI: 10.1161/01.hyp.0000257914.80918.72] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chronic treatment with the immunosuppressive drug rapamycin leads to hypertension; however, the mechanisms are unknown. Rapamycin binds FK506 binding protein 12 and its related isoform 12.6 (FKBP12/12.6) and displaces them from intracellular Ca2+ release channels (ryanodine receptors) eliciting a Ca2+ leak from the endoplasmic/sarcoplasmic reticulum. We tested whether this Ca2+ leak promotes conventional protein kinase C-mediated endothelial NO synthase phosphorylation at Thr495, which reduces production of the vasodilator NO. Rapamycin treatment of control mice for 7 days, as well as genetic deletion of FKBP12.6, increased systolic arterial pressure significantly compared with controls. Untreated aortas from FKBP12.6-/- mice and in vitro rapamycin-treated control aortas had similarly decreased endothelium-dependent relaxation responses and NO production and increased endothelial NO synthase Thr495 phosphorylation and protein kinase C activity. Inhibition of either conventional protein kinase C or ryanodine receptor restored endothelial NO synthase Thr495 phosphorylation and endothelial function to control levels. Rapamycin induced a small increase in basal intracellular Ca2+ levels in isolated endothelial cells, and rapamycin or FKBP12.6 gene deletion decreased acetylcholine-induced intracellular Ca2+ release, all of which were reversed by ryanodine. These data demonstrate that displacement of FKBP12/12.6 from ryanodine receptors induces an endothelial intracellular Ca2+ leak and increases conventional protein kinase C-mediated endothelial NO synthase Thr495 phosphorylation leading to decreased NO production and endothelial dysfunction. This molecular mechanism may, in part, explain rapamycin-induced hypertension.
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Affiliation(s)
- Cheng Long
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Tex 77030, USA
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48
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Li S, Xie L, Meng Q, Zhang R. Significance of the extra C-terminal tail of CaLP, a novel calmodulin-like protein involved in oyster calcium metabolism. Comp Biochem Physiol B Biochem Mol Biol 2006; 144:463-71. [PMID: 16759893 DOI: 10.1016/j.cbpb.2006.04.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 04/14/2006] [Accepted: 04/22/2006] [Indexed: 11/22/2022]
Abstract
Oyster (Pinctada fucata) calmodulin-like protein (CaLP), containing a C-terminally extra hydrophilic tail (150D-161K), is a novel protein involved in the regulation of oyster calcium metabolism. To investigate the importance of the extra fragment to the Ca(2+)/Mg(2+)-dependent conformational changes in the intact CaLP molecule and the interactions between CaLP and its target proteins, a truncated CaLP mutant (M-CaLP) devoid of the extended C-terminus was constructed and overexpressed in Escherichia coli. The conformational characteristics of M-CaLP were studied by CD and fluorescence spectroscopy and compared with those of the oyster CaM and CaLP. The far-UV CD results reveal that the extra tail has a strong effect on the Ca(2+)-induced, but a relatively weak effect on the Mg(2+)-induced conformational changes in CaLP. However, upon Ca2+ or Mg2+ binding, only slight changes for intrinsic phenylalanine and tyrosine fluorescence spectra between M-CaLP and CaLP are observed. Our results also indicate that the extra tail can significantly decrease the exposure of the hydrophobic patches in CaLP. Additionally, affinity chromatography demonstrates that the target binding of CaLP is greatly influenced by its additional tail. All our results implicate that the extra tail may play some important roles in the interactions between CaLP and its targets in vivo.
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Affiliation(s)
- Shuo Li
- Institute of Marine Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, China
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49
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Spratt DE, Newman E, Mosher J, Ghosh DK, Salerno JC, Guillemette JG. Binding and activation of nitric oxide synthase isozymes by calmodulin EF hand pairs. FEBS J 2006; 273:1759-71. [PMID: 16623711 DOI: 10.1111/j.1742-4658.2006.05193.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Calmodulin (CaM) is a cytosolic Ca(2+) signal-transducing protein that binds and activates many different cellular enzymes with physiological relevance, including the nitric oxide synthase (NOS) isozymes. CaM consists of two globular domains joined by a central linker; each domain contains an EF hand pair. Four different mutant CaM proteins were used to investigate the role of the two CaM EF hand pairs in the binding and activation of the mammalian inducible NOS (iNOS) and the constitutive NOS (cNOS) enzymes, endothelial NOS (eNOS) and neuronal NOS (nNOS). The role of the CaM EF hand pairs in different aspects of NOS enzymatic function was monitored using three assays that monitor electron transfer within a NOS homodimer. Gel filtration studies were used to determine the effect of Ca(2+) on the dimerization of iNOS when coexpressed with CaM and the mutant CaM proteins. Gel mobility shift assays were performed to determine binding stoichiometries of CaM proteins to synthetic NOS CaM-binding domain peptides. Our results show that the N-terminal EF hand pair of CaM contains important binding and activating elements for iNOS, whereas the N-terminal EF hand pair in conjunction with the central linker region is required for cNOS enzyme binding and activation. The iNOS enzyme must be coexpressed with wild-type CaM in vitro because of its propensity to aggregate when residues of the highly hydrophobic CaM-binding domain are exposed to an aqueous environment. A possible role for iNOS aggregation in vivo is also discussed.
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50
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Stuehr DJ, Wei CC, Wang Z, Hille R. Exploring the redox reactions between heme and tetrahydrobiopterin in the nitric oxide synthases. Dalton Trans 2005:3427-35. [PMID: 16234921 DOI: 10.1039/b506355h] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The NO synthases (NOSs) catalyze a two-step oxidation of L-arginine (Arg) to generate nitric oxide (NO) plus L-citrulline. Because NOSs are the only hemeproteins known to contain tetrahydrobiopterin (H4B) as a bound cofactor, the function and role of H4B in their heme-based oxygen activation and catalysis is of current interest. Distinct oxidative and reductive transitions of bound H4B cofactor occur during catalysis and are associated with distinct redox transitions of the NOS heme and flavin prosthetic groups. In this perspective, we discuss the redox transitions of H4B and heme with regard to their kinetics, regulation, role in the catalytic mechanism, and how and why they may be linked.
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Affiliation(s)
- Dennis J Stuehr
- Lerner Research Institute, Cleveland Clinic, Ohio State University, USA
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