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Sobieszczuk-Nowicka E, Arasimowicz-Jelonek M, Tanwar UK, Floryszak-Wieczorek J. Plant homocysteine, a methionine precursor and plant's hallmark of metabolic disorders. FRONTIERS IN PLANT SCIENCE 2022; 13:1044944. [PMID: 36570932 PMCID: PMC9773845 DOI: 10.3389/fpls.2022.1044944] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
Homocysteine (Hcy) is a sulfur-containing non-proteinogenic amino acid, which arises from redox-sensitive methionine metabolism. In plants, Hcy synthesis involves both cystathionine β-lyase and S-adenosylhomocysteine hydrolase activities. Thus, Hcy itself is crucial for de novo methionine synthesis and S-adenosylmethionine recycling, influencing the formation of ethylene, polyamines, and nicotianamine. Research on mammalian cells has shown biotoxicity of this amino acid, as Hcy accumulation triggers oxidative stress and the associated lipid peroxidation process. In addition, the presence of highly reactive groups induces Hcy and Hcy derivatives to modify proteins by changing their structure and function. Currently, Hcy is recognized as a critical, independent hallmark of many degenerative metabolic diseases. Research results indicate that an enhanced Hcy level is also toxic to yeast and bacteria cells. In contrast, in the case of plants the metabolic status of Hcy remains poorly examined and understood. However, the presence of the toxic Hcy metabolites and Hcy over-accumulation during the development of an infectious disease seem to suggest harmful effects of this amino acid also in plant cells. The review highlights potential implications of Hcy metabolism in plant physiological disorders caused by environmental stresses. Moreover, recent research advances emphasize that recognizing the Hcy mode of action in various plant systems facilitates verification of the potential status of Hcy metabolites as bioindicators of metabolism disorders and thus may constitute an element of broadly understood biomonitoring.
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Affiliation(s)
- Ewa Sobieszczuk-Nowicka
- Department of Plant Physiology, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland
| | | | - Umesh Kumar Tanwar
- Department of Plant Physiology, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland
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Sharma GS, Bhattacharya R, Singh LR. Functional inhibition of redox regulated heme proteins: A novel mechanism towards oxidative stress induced by homocysteine. Redox Biol 2021; 46:102080. [PMID: 34325357 PMCID: PMC8334742 DOI: 10.1016/j.redox.2021.102080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 07/22/2021] [Indexed: 11/19/2022] Open
Abstract
Homocysteine (Hcy) is a sulfur containing non-protein toxic amino acid synthesized from methionine. Elevated level of Hcy is associated with cardiovascular complications and neurodegeneration. Hcy is believed to induce organ damage and apoptosis via oxidative stress. The pro-oxidant nature of Hcy is considered to originate from the metal-induced oxidation of thiol group-containing molecules forming disulfides (Hcy-Hcy, Hcy-cysteine, Hcy-glutathione, etc) or with free cysteine residues of proteins (a process called protein S-homocysteinylation). Formation of such disulfides indeed results in the generation of reactive oxygen species (ROS) which eventually leads to loss of cellular integrity. In the present manuscript, we performed systematic investigation of the effect of Hcy on iron containing proteins. We discover a novel mechanism of Hcy toxicity wherein Hcy oxidation is linked with the functional loss of the protein with iron as cofactors. Our results indicate that redox regulated heme proteins might be primarily involved in the Hcy toxicity and associated oxidative stress.
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Affiliation(s)
- Gurumayum Suraj Sharma
- Department of Botany, Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi, 110075, India
| | - Reshmee Bhattacharya
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, 110007, India
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S-Homocysteinylation effects on transthyretin: worsening of cardiomyopathy onset. Biochim Biophys Acta Gen Subj 2020; 1864:129453. [DOI: 10.1016/j.bbagen.2019.129453] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/09/2019] [Accepted: 09/30/2019] [Indexed: 11/19/2022]
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Martí-Carvajal AJ, Solà I, Lathyris D, Dayer M. Homocysteine-lowering interventions for preventing cardiovascular events. Cochrane Database Syst Rev 2017; 8:CD006612. [PMID: 28816346 PMCID: PMC6483699 DOI: 10.1002/14651858.cd006612.pub5] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Cardiovascular disease, which includes coronary artery disease, stroke and peripheral vascular disease, is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor for cardiovascular disease is an elevated circulating total homocysteine level. The impact of homocysteine-lowering interventions, given to patients in the form of vitamins B6, B9 or B12 supplements, on cardiovascular events has been investigated. This is an update of a review previously published in 2009, 2013, and 2015. OBJECTIVES To determine whether homocysteine-lowering interventions, provided to patients with and without pre-existing cardiovascular disease are effective in preventing cardiovascular events, as well as reducing all-cause mortality, and to evaluate their safety. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 5), MEDLINE (1946 to 1 June 2017), Embase (1980 to 2017 week 22) and LILACS (1986 to 1 June 2017). We also searched Web of Science (1970 to 1 June 2017). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search. SELECTION CRITERIA We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease. DATA COLLECTION AND ANALYSIS We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We calculated the number needed to treat for an additional beneficial outcome (NNTB). We measured statistical heterogeneity using the I2 statistic. We used a random-effects model. We conducted trial sequential analyses, Bayes factor, and fragility indices where appropriate. MAIN RESULTS In this third update, we identified three new randomised controlled trials, for a total of 15 randomised controlled trials involving 71,422 participants. Nine trials (60%) had low risk of bias, length of follow-up ranged from one to 7.3 years. Compared with placebo, there were no differences in effects of homocysteine-lowering interventions on myocardial infarction (homocysteine-lowering = 7.1% versus placebo = 6.0%; RR 1.02, 95% confidence interval (CI) 0.95 to 1.10, I2 = 0%, 12 trials; N = 46,699; Bayes factor 1.04, high-quality evidence), death from any cause (homocysteine-lowering = 11.7% versus placebo = 12.3%, RR 1.01, 95% CI 0.96 to 1.06, I2 = 0%, 11 trials, N = 44,817; Bayes factor = 1.05, high-quality evidence), or serious adverse events (homocysteine-lowering = 8.3% versus comparator = 8.5%, RR 1.07, 95% CI 1.00 to 1.14, I2 = 0%, eight trials, N = 35,788; high-quality evidence). Compared with placebo, homocysteine-lowering interventions were associated with reduced stroke outcome (homocysteine-lowering = 4.3% versus comparator = 5.1%, RR 0.90, 95% CI 0.82 to 0.99, I2 = 8%, 10 trials, N = 44,224; high-quality evidence). Compared with low doses, there were uncertain effects of high doses of homocysteine-lowering interventions on stroke (high = 10.8% versus low = 11.2%, RR 0.90, 95% CI 0.66 to 1.22, I2 = 72%, two trials, N = 3929; very low-quality evidence).We found no evidence of publication bias. AUTHORS' CONCLUSIONS In this third update of the Cochrane review, there were no differences in effects of homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination comparing with placebo on myocardial infarction, death from any cause or adverse events. In terms of stroke, this review found a small difference in effect favouring to homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination comparing with placebo.There were uncertain effects of enalapril plus folic acid compared with enalapril on stroke; approximately 143 (95% CI 85 to 428) people would need to be treated for 5.4 years to prevent 1 stroke, this evidence emerged from one mega-trial.Trial sequential analyses showed that additional trials are unlikely to increase the certainty about the findings of this issue regarding homocysteine-lowering interventions versus placebo. There is a need for additional trials comparing homocysteine-lowering interventions combined with antihypertensive medication versus antihypertensive medication, and homocysteine-lowering interventions at high doses versus homocysteine-lowering interventions at low doses. Potential trials should be large and co-operative.
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Wilbs J, Middendorp SJ, Heinis C. Improving the Binding Affinity of in-Vitro-Evolved Cyclic Peptides by Inserting Atoms into the Macrocycle Backbone. Chembiochem 2016; 17:2299-2303. [DOI: 10.1002/cbic.201600336] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Jonas Wilbs
- Institute of Chemical Sciences and Engineering; Ecole Polytechnique Fédérale de Lausanne; EPFL); 1015 Lausanne Switzerland
| | - Simon J. Middendorp
- Institute of Chemical Sciences and Engineering; Ecole Polytechnique Fédérale de Lausanne; EPFL); 1015 Lausanne Switzerland
| | - Christian Heinis
- Institute of Chemical Sciences and Engineering; Ecole Polytechnique Fédérale de Lausanne; EPFL); 1015 Lausanne Switzerland
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Homocystinuria: Therapeutic approach. Clin Chim Acta 2016; 458:55-62. [PMID: 27059523 DOI: 10.1016/j.cca.2016.04.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 04/02/2016] [Accepted: 04/03/2016] [Indexed: 11/22/2022]
Abstract
Homocystinuria is a disorder of sulfur metabolism pathway caused by deficiency of cystathionine β-synthase (CBS). It is characterized by increased accumulation of homocysteine (Hcy) in the cells and plasma. Increased homocysteine results in various vascular and neurological complications. Present strategies to lower cellular and plasma homocysteine levels include vitamin B6 intake, dietary methionine restriction, betaine supplementation, folate and vitamin B12 administration. However, these strategies are inefficient for treatment of homocystinuria. In recent years, advances have been made towards developing new strategies to treat homocystinuria. These mainly include functional restoration to mutant CBS, enhanced clearance of Hcy from the body, prevention of N-homocysteinylation-induced toxicity and inhibition of homocysteine-induced oxidative stress. In this review, we have exclusively discussed the recent advances that have been achieved towards the treatment of homocystinuria. The review is an attempt to help clinicians in developing effective therapeutic strategies and designing novel drugs against homocystinuria.
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Lahiri KD, Mukherjee S, Ghosh S, Mukherjee S, Dutta J, Datta H, Das HN. Hyperhomocysteinemia, a biochemical tool for differentiating ischemic and nonischemic central retinal vein occlusion during the early acute phase. KOREAN JOURNAL OF OPHTHALMOLOGY 2015; 29:86-91. [PMID: 25829824 PMCID: PMC4369522 DOI: 10.3341/kjo.2015.29.2.86] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 07/08/2014] [Indexed: 11/23/2022] Open
Abstract
PURPOSE The purpose of the study was to differentiate ischemic central retinal vein occlusion (CRVO) from nonischemic CRVO during the early acute phase using plasma homocysteine as a biochemical marker. METHODS Fasting plasma homocysteine, serum vitamin B12, and folate levels were measured in 108 consecutive unilateral elderly adult (age >50 years) ischemic CRVO patients in the absence of local and systemic disease and compared with a total of 144 age and sex matched nonischemic CRVO patients and 120 age and sex matched healthy control subjects. RESULTS Homocysteine level was significantly increased in the patients with ischemic CRVO in comparison with nonischemic CRVO patients (p = 0.009) and also in comparison with control subjects (p < 0.001). Analysis also showed that hyperhomocysteinemia was associated with increased incidence of ischemic CRVO (odds ratio, 18) than that for nonischemic CRVO (odds ratio, 4.5). Serum vitamin B12 and folate levels were significantly lower (p < 0.001) in CRVO patients compared to the control but were not significantly different between nonischemic and ischemic CRVO patients (p > 0.1). CONCLUSIONS Hyperhomocysteinemia can be regarded as useful in differentiating nonischemic and ischemic CRVO during the early acute phase in absence of local and systemic disease in the elderly adult (age >50 years) population.
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Affiliation(s)
- Kapil Deb Lahiri
- Department of Biochemistry, ESI-PGIMSR & ESIC Medical College Joka, Kolkata, India
| | | | - Sambuddha Ghosh
- Department of Ophthalmology, North Bengal Medical College, Siliguri, India
| | - Suman Mukherjee
- Department of Ophthalmology, Regional Institute of Ophthalmology, Kolkata, India
| | - Jayanta Dutta
- Department of Ophthalmology, Regional Institute of Ophthalmology, Kolkata, India
| | - Himadri Datta
- Department of Ophthalmology, Regional Institute of Ophthalmology, Kolkata, India
| | - Harendra Nath Das
- Department of Biochemistry, RG Kar Medical College & Hospital, Kolkata, India
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Hellmich MR, Coletta C, Chao C, Szabo C. The therapeutic potential of cystathionine β-synthetase/hydrogen sulfide inhibition in cancer. Antioxid Redox Signal 2015; 22:424-48. [PMID: 24730679 PMCID: PMC4307161 DOI: 10.1089/ars.2014.5933] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 04/14/2014] [Indexed: 12/14/2022]
Abstract
SIGNIFICANCE Cancer represents a major socioeconomic problem; there is a significant need for novel therapeutic approaches targeting tumor-specific pathways. RECENT ADVANCES In colorectal and ovarian cancers, an increase in the intratumor production of hydrogen sulfide (H2S) from cystathionine β-synthase (CBS) plays an important role in promoting the cellular bioenergetics, proliferation, and migration of cancer cells. It also stimulates peritumor angiogenesis inhibition or genetic silencing of CBS exerts antitumor effects both in vitro and in vivo, and potentiates the antitumor efficacy of anticancer therapeutics. CRITICAL ISSUES Recently published studies are reviewed, implicating CBS overexpression and H2S overproduction in tumor cells as a tumor-growth promoting "bioenergetic fuel" and "survival factor," followed by an overview of the experimental evidence demonstrating the anticancer effect of CBS inhibition. Next, the current state of the art of pharmacological CBS inhibitors is reviewed, with special reference to the complex pharmacological actions of aminooxyacetic acid. Finally, new experimental evidence is presented to reconcile a controversy in the literature regarding the effects of H2S donor on cancer cell proliferation and survival. FUTURE DIRECTIONS From a basic science standpoint, future directions in the field include the delineation of the molecular mechanism of CBS up-regulation of cancer cells and the delineation of the interactions of H2S with other intracellular pathways of cancer cell metabolism and proliferation. From the translational science standpoint, future directions include the translation of the recently emerging roles of H2S in cancer into human diagnostic and therapeutic approaches.
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Affiliation(s)
- Mark R. Hellmich
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas
| | - Ciro Coletta
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas
| | - Celia Chao
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas
| | - Csaba Szabo
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas
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Martí-Carvajal AJ, Solà I, Lathyris D. Homocysteine-lowering interventions for preventing cardiovascular events. Cochrane Database Syst Rev 2015; 1:CD006612. [PMID: 25590290 DOI: 10.1002/14651858.cd006612.pub4] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Cardiovascular disease, which includes coronary artery disease, stroke and congestive heart failure, is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor is an elevated circulating total homocysteine level, which is associated with cardiovascular events. The impact of homocysteine-lowering interventions, given to patients in the form of vitamins B6, B9 or B12 supplements, on cardiovascular events. This is an update of a review previously published in 2009 and 2013. OBJECTIVES To determine whether homocysteine-lowering interventions, provided in patients with and without pre-existing cardiovascular disease are effective in preventing cardiovascular events, as well as all-cause mortality and evaluate their safety. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2014, Issue 1), MEDLINE (1950 to January week 5 2014), EMBASE (1980 to 2014 week 6) and LILACS (1986 to February 2014). We also searched Web of Science (1970 to 7 February 2014). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search. SELECTION CRITERIA We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease. DATA COLLECTION AND ANALYSIS We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a random-effects model. MAIN RESULTS In this second updated Cochrane Review, we identified no new randomised controlled trials. Therefore, this new version includes 12 randomised controlled trials involving 47,429 participants. In general terms, 75% (9/12) trials had a low risk of bias. Homocysteine-lowering interventions compared with placebo did not significantly affect non-fatal or fatal myocardial infarction (1743/23,590 (7.38%) versus 1247/20,190 (6.17%); RR 1.02, 95% confidence interval (CI) 0.95 to 1.10, I(2) = 0%, high quality evidence), stroke (968/22,348 (4.33%) versus 974/18,957 (5.13%); RR 0.91, 95% CI 0.82 to 1.0, I(2) = 11%, high quality evidence) or death from any cause (2784/22,648 (12.29%) versus 2502/19,250 (10.64%); RR 1.01, 95% CI 0.96 to 1.07, I(2) = 6%, high quality evidence). Homocysteine-lowering interventions compared with placebo did not significantly affect serious adverse events (cancer) (1558/18,130 (8.59%) versus 1334/14,739 (9.05%); RR 1.06, 95% CI 0.98 to 1.13; I(2) = 0%, high quality evidence). AUTHORS' CONCLUSIONS This second update of this Cochrane Review found no evidence to suggest that homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination should be used for preventing cardiovascular events. Furthermore, there is no evidence to suggest that homocysteine-lowering interventions are associated with an increased risk of cancer.
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Lahiri KD, Datta H, Das HN. Reference interval determination of total plasma homocysteine in an Indian population. Indian J Clin Biochem 2014; 29:74-8. [PMID: 24478553 PMCID: PMC3903923 DOI: 10.1007/s12291-013-0304-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 01/18/2013] [Indexed: 10/27/2022]
Abstract
Hyperhomocysteinemia has been shown to be an independent risk factor for cardiovascular disease as well as retinal vascular occlusion. Because of the epidemiological, dietary, genetic and environmental diversity among the different countries, each country should establish the reference interval of homocysteine of their own population for recommending appropriate medical decision limits. Hence a total of 1,288 apparently healthy subjects including 636 male and 652 female were enrolled in the present study to determine the reference intervals of homocysteine in an Indian population. Results of the study were presented as mean, standard deviation, median and 2.5th and 97.5th percentile with the 0.90 confidence interval of each percentile values of homocysteine along with decade-wise changes.
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Affiliation(s)
- Kapil D. Lahiri
- />R. G. Kar Medical College & Hospital, 4/2 Shibchandra Sarbabhowma Lane, Baranagar, Kolkata, 700036 West Bengal India
| | - Himadri Datta
- />Department of Ophthalmology, Regional Institute of Ophthalmology, Kolkata, India
| | - Harendra N. Das
- />Department of Biochemistry, R.G. Kar Medical College & Hospital, Kolkata, India
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Jakubowski H. The Mechanism and Consequences of Homocysteine Incorporation Into Protein in Humans. PHOSPHORUS SULFUR 2013. [DOI: 10.1080/10426507.2012.736104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Hieronim Jakubowski
- a Department of Microbiology & Molecular Genetics, UMDNJ-New Jersey Medical School , International Center for Public Health , Newark , NJ , USA
- b Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, and Department of Biochemistry and Biotechnology , University of Life Sciences , Poznań , Poland
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S-linked protein homocysteinylation: identifying targets based on structural, physicochemical and protein-protein interactions of homocysteinylated proteins. Amino Acids 2013; 44:1307-16. [PMID: 23400378 DOI: 10.1007/s00726-013-1465-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 01/23/2013] [Indexed: 10/27/2022]
Abstract
An elevated level of homocysteine, a thiol-containing amino acid is associated with a wide spectrum of disease conditions. A majority (>80 %) of the circulating homocysteine exist in protein-bound form. Homocysteine can bind to free cysteine residues in the protein or could cleave accessible cysteine disulfide bonds via thiol disulfide exchange reaction. Binding of homocysteine to proteins could potentially alter the structure and/or function of the protein. To date only 21 proteins have been experimentally shown to bind homocysteine. In this study we attempted to identify other proteins that could potentially bind to homocysteine based on the criteria that such proteins will have significant 3D structural homology with the proteins that have been experimentally validated and have solvent accessible cysteine residues either with high dihedral strain energy (for cysteine-cysteine disulfide bonds) or low pKa (for free cysteine residues). This analysis led us to the identification of 78 such proteins of which 68 proteins had 154 solvent accessible disulfide cysteine pairs with high dihedral strain energy and 10 proteins had free cysteine residues with low pKa that could potentially bind to homocysteine. Further, protein-protein interaction network was built to identify the interacting partners of these putative homocysteine binding proteins. We found that the 21 experimentally validated proteins had 174 interacting partners while the 78 proteins identified in our analysis had 445 first interacting partners. These proteins are mainly involved in biological activities such as complement and coagulation pathway, focal adhesion, ECM-receptor, ErbB signalling and cancer pathways, etc. paralleling the disease-specific attributes associated with hyperhomocysteinemia.
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Arasimowicz-Jelonek M, Floryszak-Wieczorek J, Gzyl J, Chmielowska-Bąk J. Homocysteine over-accumulation as the effect of potato leaves exposure to biotic stress. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 63:177-84. [PMID: 23266362 DOI: 10.1016/j.plaphy.2012.11.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 11/28/2012] [Indexed: 05/03/2023]
Abstract
Homocysteine (Hcy) is a naturally occurring intermediate metabolite formed during methionine metabolism. It has been well documented that its excess can be extremely toxic to mammalian, yeast and bacterial cells. In spite of the metabolic value of Hcy known for decades, the role of this amino acid in the plant response to stress has not been recognized yet. In the presented study, using potato plant (Solanum tuberosum L.) and Phytophthora infestans as a model system, the presence and tissue localization of Hcy in leaves was examined by an immunohistochemical method. The over-production of Hcy was more evidenced in the susceptible than in the resistant genotype of potato starting from 48 hpi. Furthermore, the elevated level of Hcy was correlated in time with the up-regulation of genes engaged in its biosynthesis, e.g. cystathionine β-lyase and S-adenosyl-l-homocysteine hydrolase. The pharmacological approach with exogenous Hcy resulted in significant rise in lipid peroxidation and more potent late blight disease development in leaves of susceptible potato as well. Finally, it has been found that key defense enzymes, i.e. phenylalanine ammonia lyase and β-1,3-glucanase were up-regulated early in the resistant potato genotype, starting from 1st hpi. In turn, in the susceptible potato the time-lag in expression of these enzymes tuned with excess production of Hcy might facilitate leaf tissue colonization by pathogen. Based on obtained results it should be stated that Hcy over-accumulation is engaged in pathophysiological mechanism leading to the abolishment of the resistance and might be an informative disease hallmark both in plant and in animal system.
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Affiliation(s)
- Magdalena Arasimowicz-Jelonek
- Department of Plant Ecophysiology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland.
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Martí-Carvajal AJ, Solà I, Lathyris D, Karakitsiou DE, Simancas-Racines D. Homocysteine-lowering interventions for preventing cardiovascular events. Cochrane Database Syst Rev 2013:CD006612. [PMID: 23440809 DOI: 10.1002/14651858.cd006612.pub3] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Cardiovascular disease (including coronary artery disease, stroke and congestive heart failure), is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor is elevated circulating total homocysteine levels, which are associated with cardiovascular events. This is an update of a review previously published in 2009. OBJECTIVES To assess the clinical effectiveness of homocysteine-lowering interventions in people with or without pre-existing cardiovascular disease. SEARCH METHODS We searched The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (2012, Issue 2), MEDLINE (1950 to Feb week 2 2012), EMBASE (1980 to 2012 week 07), and LILACS (1986 to February 2012). We also searched ISI Web of Science (1970 to February 2012). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search. SELECTION CRITERIA We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease. DATA COLLECTION AND ANALYSIS We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using I(2). We used a random-effects model. MAIN RESULTS In this updated systematic review, we identified four new randomised trials, resulting in a total of 12 randomised controlled trials involving 47,429 participants. In general terms, the trials had a low risk of bias. Homocysteine-lowering interventions compared with placebo did not significantly affect non-fatal or fatal myocardial infarction (pooled RR 1.02, 95% CI 0.95 to 1.10, I(2) = 0%), stroke (pooled RR 0.91, 95% CI 0.82 to 1.0, I(2) = 11%) or death by any cause (pooled RR 1.01 (95% CI 0.96 to 1.07, I(2): 6%)). Homocysteine-lowering interventions compared with placebo did not significantly affect serious adverse events (cancer) (1 RR 1.06, 95% CI 0.98 to 1.13; I(2) = 0%). AUTHORS' CONCLUSIONS This updated Cochrane review found no evidence to suggest that homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination should be used for preventing cardiovascular events. Furthermore, there is no evidence suggesting that homocysteine-lowering interventions are associated with an increased risk of cancer.
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Affiliation(s)
- Arturo J Martí-Carvajal
- Facultad de Ciencias de la Salud Eugenio Espejo, Universidad Tecnológica Equinoccial, Quito, Ecuador.
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Lahiri KD, Dutta J, Datta H, Das HN. Hyperhomocysteinemia, as an independent risk factor for retinal venous occlusion in an Indian population. Indian J Clin Biochem 2012; 28:61-4. [PMID: 24381423 DOI: 10.1007/s12291-012-0238-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 06/20/2012] [Indexed: 11/29/2022]
Abstract
Total plasma homocysteine was analysed in 64 cases of retinal vein occlusion (RVO) of which 24 cases of central retinal vein occlusion (CRVO) and 40 cases of branch retinal vein occlusion (BRVO) and compared with 45 age and sex matched control. Homocysteine was significantly increased in RVO cases in respect to control (P < 0.001). Analysis also revealed that prevalence of rise of plasma homocysteine was more in cases of CRVO (OR = 13) than that of BRVO (OR = 5.03).
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Affiliation(s)
- Kapil D Lahiri
- Department of Biochemistry, RG Kar Medical College and Hospital, Kolkata, India ; 4/2 Shibchandra Sarbabhowma Lane, Baranagar, Kolkata, 700036 West Bengal India
| | - Jayanta Dutta
- Department of Ophthalmology, Regional Institute of Ophthalmology, Kolkata, India
| | - Himadri Datta
- Department of Ophthalmology, Regional Institute of Ophthalmology, Kolkata, India
| | - Harendra N Das
- Department of Biochemistry, RG Kar Medical College and Hospital, Kolkata, India
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Kassab A, Piwowar A. Cell oxidant stress delivery and cell dysfunction onset in type 2 diabetes. Biochimie 2012; 94:1837-48. [PMID: 22333037 DOI: 10.1016/j.biochi.2012.01.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 01/25/2012] [Indexed: 01/18/2023]
Abstract
Most known pathways of diabetic complications involve oxidative stress. The mitochondria electron transport chain is a significant source of reactive oxygen species (ROS) in insulin secretory cells, insulin peripheral sensitive cells and endothelial cells. Elevated intracellular glucose level induces tricarboxylic acid cycle electron donor overproduction and mitochondrial proton gradient increase leading to an increase in electron transporter lifetime. Subsequently, the electrons leaked combine with respiratory oxygen (O(2)) resulting in superoxide anion ((•)O(2)(-)) production. Advanced glycation end products derive ROS via interaction with their receptors. Elevated diacylglycerol and ROS activate the protein kinase C pathway which, in turn, activates NADPH oxidases. A vicious circle of pathway derived ROS installs. Pathologic pathways induced ROS are activated and persistent though glycemia returns to normal due to hyperglycemia memory. Endothelial nitric oxide synthase may produce both superoxide anion ((•)O(2)(-)) and nitric oxide (NO) leading to peroxynitrite ((•)ONOO(-)) generation. Homocysteine is also implicated in oxidative stress pathogenesis. In this paper we have highlighted the pathologic mechanisms of ROS on atherosclerosis, renal dysfunction, retina dysfunction and nerve dysfunction in type 2 diabetes. Cell oxidant stress delivery have pivotal role in cell dysfunction onset and progression of angiopathies but an early introduction of good glycemic control may protect cells more efficiently than antioxidants.
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Affiliation(s)
- Asma Kassab
- Biochemistry Laboratory, CHU Farhat Hached, Sousse, Tunisia.
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Kanth VVR, Golla JP, Sastry BKS, Naik S, Kabra N, Sujatha M. Genetic interactions between MTHFR (C677T), methionine synthase (A2756G, C2758G) variants with vitamin B12 and folic acid determine susceptibility to premature coronary artery disease in Indian population. J Cardiovasc Dis Res 2011; 2:156-63. [PMID: 22022143 PMCID: PMC3195194 DOI: 10.4103/0975-3583.85262] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Background: Researchers have determined that Indians face a higher risk of heart disease, despite the fact that nearly half of them are vegetarians and lack many of the other traditional risk factors. In the below-30 age group, coronary artery disease mortality among Indians is three-fold higher than in the whites in United Kingdom and ten-fold higher than the Chinese in Singapore. High levels of homocysteine have been widely linked to the early onset of heart diseases in other populations, although a definite proof among Indians is lacking, which needs to be investigated by way of screening for factors responsible for high homocysteine levels. Objective: To screen for genetic factors responsible for hyperhomocysteinemia and the risk for premature coronary artery disease. Materials and Methods: A total of 100 individuals with proven premature coronary artery disease and 200 age-and-sex matched controls were screened for polymorphisms in Methylenetetrahydrofolate reductase (MTHFR) (C677T) Methionine synthase (MS) genes (A2756G, C2758G), and the B12 and Folate levels were estimated. Results: Results from the mutational analysis revealed that in the study group, seven individuals had a polymorphism for the C677T allele in the MTHFR gene (one homozygous and six heterozygous) (Fischer's Exact test P > 0.046) (OR: 0.2711 95% CI 0.0774 to 0.9491). Six were heterozygous for the A2756G polymorphism in the MS gene (Fischer's Exact test P > 0.0012). None showed a polymorphism at the C2758G allele in the MS gene. Four controls showed heterozygosity for the C677T polymorphism and none for the MS gene. The B12 and Folate levels were significantly lower in the study group as compared to the controls. Conclusions: It is important to know which factors determine the total homocysteine concentrations. In the general population, the most important modifiable determinants of tHcy are folate intake and coffee consumption. Smoking and alcohol consumption are also associated with the total homocysteine concentrations, but more research is necessary to elucidate whether these relations are not originating from residual confounding due to other lifestyle factors.
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Affiliation(s)
- V V Ravi Kanth
- Department of Clinical Genetics, Institute of Genetics and Hospital for Genetic Diseases, Osmania University, Begumpet, Hyderabad, Andhra Pradesh, India
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18
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Abstract
In hypertension, an increase in arterial wall thickness and loss of elasticity over time result in an increase in pulse wave velocity, a direct measure of arterial stiffness. This change is reflected in gradual fragmentation and loss of elastin fibers and accumulation of stiffer collagen fibers in the media that occurs independently of atherosclerosis. Similar results are seen with an elevated level of homocysteine (Hcy), known as hyperhomocysteinemia (HHcy), which increases vascular thickness, elastin fragmentation, and arterial blood pressure. Studies from our laboratory have demonstrated a decrease in elasticity and an increase in pulse wave velocity in HHcy cystathionine β synthase heterozygote knockout (CBS(-/+)) mice. Nitric oxide (NO) is a potential regulator of matrix metalloproteinase (MMP) activity in MMP-NO-TIMP (tissue inhibitor of metalloproteinase) inhibitory tertiary complex. We have demonstrated the contribution of the NO synthase (NOS) isoforms, endothelial NOS and inducible NOS, in the activation of latent MMP. The differential production of NO contributes to oxidative stress and increased oxidative/nitrative activation of MMP resulting in vascular remodeling in response to HHcy. The contribution of the NOS isoforms, endothelial and inducible in the collagen/elastin switch, has been demonstrated. We have showed that an increase in inducible NOS activity is a key contributor to HHcy-mediated collagen/elastin switch and resulting decline in aortic compliance. In addition, increased levels of Hcy compete and suppress the γ-amino butyric acid-receptor, N-methyl-d-aspartate-receptor, and peroxisome proliferator-activated receptor. The HHcy causes oxidative stress by generating nitrotyrosine, activating the latent MMPs and decreasing the endothelial NO concentration. The HHcy causes elastinolysis and decrease elastic complicance of the vessel wall. The treatment with γ-amino butyric acid-receptor agonist (muscimol), N-methyl-d-aspartate-receptor antagonist (MK-801), and peroxisome proliferator-activated receptor agonists (ciprofibrate and ciglitazone) mitigates the cardiovascular dysfunction in HHcy [corrected].
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Affiliation(s)
- Mesia M Steed
- Department of Physiology and Biophysics, University of Louisville School of Medicine, 500 South Preston Street, Louisville, KY 40202, USA
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19
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Tang YS, Khan RA, Zhang Y, Xiao S, Wang M, Hansen DK, Jayaram HN, Antony AC. Incrimination of heterogeneous nuclear ribonucleoprotein E1 (hnRNP-E1) as a candidate sensor of physiological folate deficiency. J Biol Chem 2011; 286:39100-15. [PMID: 21930702 DOI: 10.1074/jbc.m111.230938] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism underlying the sensing of varying degrees of physiological folate deficiency, prior to adaptive optimization of cellular folate uptake through the translational up-regulation of folate receptors (FR) is unclear. Because homocysteine, which accumulates intracellularly during folate deficiency, stimulated interactions between heterogeneous nuclear ribonucleoprotein E1 (hnRNP-E1) and an 18-base FR-α mRNA cis-element that led to increased FR biosynthesis and net up-regulation of FR at cell surfaces, hnRNP-E1 was a plausible candidate sensor of folate deficiency. Accordingly, using purified components, we evaluated the physiological basis whereby L-homocysteine triggered these RNA-protein interactions to stimulate FR biosynthesis. L-homocysteine induced a concentration-dependent increase in RNA-protein binding affinity throughout the range of physiological folate deficiency, which correlated with a proportionate increase in translation of FR in vitro and in cultured human cells. Targeted reduction of newly synthesized hnRNP-E1 proteins by siRNA to hnRNP-E1 mRNA reduced both constitutive and L-homocysteine-induced rates of FR biosynthesis. Furthermore, L-homocysteine covalently bound hnRNP-E1 via multiple protein-cysteine-S-S-homocysteine mixed disulfide bonds within K-homology domains known to interact with mRNA. These data suggest that a concentration-dependent, sequential disruption of critical cysteine-S-S-cysteine bonds by covalently bound L-homocysteine progressively unmasks an underlying RNA-binding pocket in hnRNP-E1 to optimize interaction with FR-α mRNA cis-element preparatory to FR up-regulation. Collectively, such data incriminate hnRNP-E1 as a physiologically relevant, sensitive, cellular sensor of folate deficiency. Because diverse mammalian and viral mRNAs also interact with this RNA-binding domain with functional consequences to their protein expression, homocysteinylated hnRNP-E1 also appears well positioned to orchestrate a novel, nutrition-sensitive (homocysteine-responsive), posttranscriptional RNA operon in folate-deficient cells.
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Affiliation(s)
- Ying-Sheng Tang
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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20
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Tewari AK, Popova-Butler A, El-Mahdy MA, Zweier JL. Identification of differentially expressed proteins in blood plasma of control and cigarette smoke-exposed mice by 2-D DIGE/MS. Proteomics 2011; 11:2051-62. [PMID: 21500341 DOI: 10.1002/pmic.201000159] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 02/04/2011] [Accepted: 02/11/2011] [Indexed: 01/23/2023]
Abstract
Cigarette smoke exposure is known to induce obstructive lung disease and several cardiovascular disease states in humans and also in animal models. Smoking leads to oxidative stress and inflammation that are important in triggering pulmonary and cardiovascular disease. The objective of the current study was to quantify differences in expression levels of plasma proteins of cigarette smoke -exposed and control mice, at the time of disease onset, and identify these proteins for use as potential biomarkers of the onset of smoking-induced disease. We utilized 2-D DIGE/MS to characterize these proteomic changes. 2-D DIGE of plasma samples identified 11 differentially expressed proteins in cigarette smoke -exposed mice. From these 11 proteins, 9 were downregulated and 2 were upregulated. The proteins identified are involved in vascular function, coagulation, metabolism and immune function. Among these, the alterations in fibrinogen (2.2-fold decrease), α-1-antitrypsin (1.8-fold increase) and arginase (4.5-fold decrease) are of particular interest since these have been directly linked to cardiovascular and lung pathology. Differences in expression levels of these proteins were also confirmed by immunoblotting. Thus, we observe that chronic cigarette smoke exposure in mice leads to prominent changes in the protein expression profile of blood plasma and these changes in turn can potentially serve as markers predictive of the onset and progression of cardiovascular and pulmonary disease.
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Affiliation(s)
- Arun K Tewari
- Center for Environmental and Smoking Induced Disease, Davis Heart and Lung Research Institute, Division of Cardiovascular Medicine, Department of Internal Medicine, Ohio State University College of Medicine, Columbus, OH 43210-1252, USA
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21
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Fedosov SN. Metabolic signs of vitamin B(12) deficiency in humans: computational model and its implications for diagnostics. Metabolism 2010; 59:1124-38. [PMID: 20051280 DOI: 10.1016/j.metabol.2009.09.036] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 09/17/2009] [Indexed: 11/19/2022]
Abstract
Early diagnostics of cobalamin (Cbl, vitamin B(12)) deficiency is primarily based on measurements of the relevant metabolic markers in blood plasma--total B(12), specific Cbl-saturated transporter holo-transcobalamin (holoTC), and substrates of Cbl-dependent enzymatic reactions methylmalonic acid (MMA) and homocysteine (Hcy). Concentrations of B(12) and holoTC decrease whereas MMA and Hcy increase under deficiency. Yet, the results of individual tests are often contradictory and do not guarantee unambiguous diagnosis. The current work describes the metabolic manifestation of vitamin B(12) deficiency in terms of flux equations fitted to data sets from literature. The model mathematically connects all the markers and presents 4 independent measurements as a single point (x, y) in the combined coordinates x = (holoTC x B(12))((1/2)) and y = (1/2)log(10)(MMA x Hcy). Pairwise averaging compensates for the individual fluctuations of the markers caused by (1) irregular spikes of holoTC, (2) delayed change of the total plasma B(12) buffered by an internal Cbl depot, and (3) variations in the production/excretion velocities of MMA and Hcy. Bivariate distribution of the marker combinations (x, y) reveals several peaks of frequency in the analyzed mixed population. The peaks seem to represent the reference subgroups with different B(12) physiology and characteristic values of "wellness parameter": w = log(10)(holoTC(n)) + log(10)(B(12n)) - log(10)(MMA(n)) - log(10)(Hcy(n)), where concentrations are normalized (eg, MMA(n) = MMA/MMA(normal)). Dynamic response of the organism to B(12) intake is quantified and described as an additional analytical tool when classifying uncertain cases. The discussed mathematical approaches are of general applicability in diagnostics.
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Affiliation(s)
- Sergey N Fedosov
- Protein Chemistry Laboratory, Department of Molecular Biology, University of Aarhus, Science Park, DK 8000 Aarhus C, Denmark.
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22
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Malinowska A, Chmurzynska A. Polymorphism of genes encoding homocysteine metabolism-related enzymes and risk for cardiovascular disease. Nutr Res 2010; 29:685-95. [PMID: 19917447 DOI: 10.1016/j.nutres.2009.09.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 09/11/2009] [Accepted: 09/23/2009] [Indexed: 11/18/2022]
Abstract
The aim of this review is to present a general overview of the relationships among homocysteine metabolism, polymorphism of the genes encoding homocysteine metabolism-related enzymes, and the nutrients influencing the plasma homocysteine level. Combining these factors creates a profile of an individual's susceptibility to complex diseases associated with hyperhomocysteinemia. Homocysteine is an amino acid derived from the demethylation of methionine. Hyperhomocysteinemia is associated with an increased risk of several complex diseases, including cardiovascular diseases. The level of plasma homocysteine depends on the combined effects of genetic and environmental factors. Polymorphisms of genes encoding homocysteine metabolism-related enzymes, such as methylenetetrahydrofolate reductase, methionine synthase, methionine synthase reductase, and cystathionine beta-synthase, influence plasma homocysteine concentration and thereby cardiovascular health. On the other hand, homocysteine metabolism may be modulated by dietary intake of the nutrients involved in homocysteine metabolism (ie, folates, vitamin B(6), and vitamin B(12)). Thus, the appropriate health-promoting doses of these nutrients may vary among certain groups of individuals, depending on their genotypes and other risk factors for complex diseases. Better understanding of the relationship between genotype and nutrition influencing the plasma total homocysteine level and cardiovascular health may improve the cardiovascular diagnostic tests (ie, measurement of biologic markers). It could be possible to define the level of progression, severity, and susceptibility to disease much earlier than it is done now. In conclusion, the introduction of combined dietary and pharmacologic treatment would be possible at the initial stages of disease.
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Affiliation(s)
- Anna Malinowska
- Department of Human Nutrition and Hygiene, Poznan University of Life Sciences, Poznan, Poland
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23
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Martí-Carvajal AJ, Solà I, Lathyris D, Salanti G. Homocysteine lowering interventions for preventing cardiovascular events. Cochrane Database Syst Rev 2009:CD006612. [PMID: 19821378 PMCID: PMC4164174 DOI: 10.1002/14651858.cd006612.pub2] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Cardiovascular disease such as coronary artery disease, stroke and congestive heart failure, is a leading cause of death worldwide. A postulated risk factor is elevated circulating total homocysteine (tHcy) levels which is influenced mainly by blood levels of cyanocobalamin (vitamin B12), folic acid (vitamin B9) and pyridoxine (vitamin B6). There is uncertainty regarding the strength of association between tHcy and the risk of cardiovascular disease. OBJECTIVES To assess the clinical effectiveness of homocysteine-lowering interventions (HLI) in people with or without pre-existing cardiovascular disease. SEARCH STRATEGY We searched The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (issue 3 2008), MEDLINE (1950 to August 2008), EMBASE (1988 to August 2008), and LILACS (1982 to September 2, 2008). We also searched in Allied and Complementary Medicine (AMED; 1985 to August 2008), ISI Web of Science (1993 to August 2008), and the Cochrane Stroke Group Specialised Register (April 2007). We hand searched pertinent journals and the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search. SELECTION CRITERIA We included randomised clinical trials (RCTs) assessing the effects of HLI for preventing cardiovascular events with a follow-up period of 1 year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease. DATA COLLECTION AND ANALYSIS We independently performed study selection, risk of bias assessment and data extraction. We estimated relative risks (RR) for dichotomous outcomes. We measured statistical heterogeneity using I(2). We used a random-effects model to synthesise the findings. MAIN RESULTS We included eight RCTs involving 24,210 participants with a low risk of bias in general terms. HLI did not reduce the risk of non-fatal or fatal myocardial infarction, stroke, or death by any cause (pooled RR 1.03, 95% CI 0.94 to 1.13, I(2) = 0%; pooled RR 0.89, 95% CI 0.73 to 1.08, I(2) = 15%); and pooled RR 1.00 (95% CI 0.92 to 1.09, I(2): 0%), respectively. AUTHORS' CONCLUSIONS Results from available published trials suggest that there is no evidence to support the use of HLI to prevent cardiovascular events.
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Affiliation(s)
| | - Ivan Solà
- Iberoamerican Cochrane Centre, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | | | - Georgia Salanti
- Clinical and Molecular Epidemiology Unit, Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina 45110, Greece
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Alioglu E, Turk U, Cam S, Abbasaliyev A, Tengiz I, Ercan E. Polymorphisms of the methylenetetrahydrofolate reductase, vascular endothelial growth factor, endothelial nitric oxide synthase, monocyte chemoattractant protein-1 and apolipoprotein E genes are not associated with carotid intima-media thickness. Can J Cardiol 2009; 25:e1-5. [PMID: 19148342 DOI: 10.1016/s0828-282x(09)70022-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Single nucleotide polymorphisms in the 5,10-methylenetetrahydrofolate reductase (MTHFR), vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), monocyte chemoattractant protein-1 (MCP-1) and apolipoprotein E (ApoE) genes appear to be a genetic risk factor for atherosclerosis. Common carotid intima-media thickness (cIMT) provides information on the severity of atherosclerosis. OBJECTIVE To investigate the relationship between cIMT and gene polymorphisms associated with atherosclerosis in Turkish patients with coronary artery disease (CAD). METHODS Sixty-two patients with angiographically diagnosed stable CAD were divided into two groups according to their cIMT values (group 1: n=35, cIMT of 1 mm or greater; group 2: n=27, cIMT of less than 1 mm). MTHFR 677 C/T, VEGF --460 C/T, eNOS 894 G/T, MCP-1 --2518 A/G and ApoE (E2, E3 and E4) gene polymorphisms (where A is adenine, C is cytosine, G is guanine and T is thymine) were analyzed by polymerase chain reaction and restriction fragment length polymorphism. Evaluations of cardiovascular risk factors and coronary atherosclerotic lesions were performed in all patients. Serum homocysteine and high-sensitivity C-reactive protein were measured and compared between the two groups. RESULTS Serum high-sensitivity C-reactive protein (P=0.04) and homocysteine (P=0.006) levels were higher in group 1 than in group 2. The ratio of multivessel CAD and previous myocardial infarction was significantly higher in group 1 than in group 2 (P=0.014). In the study population, no significant difference in cIMT was observed according to the polymorphisms studied. Only hyperhomocysteinemia (OR 1.17 [95% CI 1.01 to 1.35], P=0.033) and previous myocardial infarction (OR 3.76 [95% CI 1.10 to 12.81], P=0.034) maintained a significant correlation with cIMT on multiple logistic regression analysis. CONCLUSION cIMT is increased in patients with hyperhomocysteinemia, inflammation and extended CAD. MTHFR 677 C/T, VEGF --460 C/T, eNOS 894 G/T, MCP-1 --2518 A/G and ApoE single nucleotide polymorphisms were not associated with increased cIMT.
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Affiliation(s)
- Emin Alioglu
- Department of Cardiology, Central Hospital, Bayrakli, Izmir, Turkey.
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Jendricko T, Vidović A, Grubisić-Ilić M, Romić Z, Kovacić Z, Kozarić-Kovacić D. Homocysteine and serum lipids concentration in male war veterans with posttraumatic stress disorder. Prog Neuropsychopharmacol Biol Psychiatry 2009; 33:134-40. [PMID: 19038303 DOI: 10.1016/j.pnpbp.2008.11.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 11/06/2008] [Accepted: 11/07/2008] [Indexed: 11/29/2022]
Abstract
The evidence of increased cardiovascular disease (CVD) risk in posttraumatic stress disorder (PTSD) is accumulating. The present study aimed to determine whether chronic, combat-related PTSD is associated with serum lipid and homocysteine concentrations that could indicate higher CVD risk. The authors tested 66 war veterans with PTSD, 33 war veterans without PTSD, and 42 healthy volunteers for serum concentrations of homocysteine, total cholesterol, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triglycerides. All the subjects were men and the analyses were adjusted for age, body mass index and smoking. Potential influences of depression, anxiety, and psychotic symptoms on the outcome measures were checked by introducing the scores from the Hamilton Depression Rating Scale (HAM-D-17), the Hamilton Anxiety Scale (HAMA), and the Positive and Negative Syndrome Scale (PANSS) into the overall statistical model. No differences in total cholesterol, LDL-C, HDL-C and triglycerides were found between the groups. Non-smoking PTSD war veterans had higher homocysteine concentrations (mean=10.4 micromol/L, SD=1.7) when compared to non-smoking war veterans without PTSD (mean=8.2 micromol/L, SD=4.0, P=0.014) and both smoking (mean=8.7 micromol/L, SD=2.3, P=0.008) and non-smoking healthy volunteers (mean=8.8 micromol/L, SD=2.2, P=0.021). The results of our cross-sectional study are possibly confounded by many factors, especially behavioral and life-style related which are difficult to control comprehensively and might have influenced serum lipids and homocysteine concentration in a complex manner. An increase in the homocysteine concentration observed in the non-smoking PTSD patients needs further investigation with a carefully designed prospective study to confirm associated, possibly enhanced CVD risk.
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Affiliation(s)
- Tihana Jendricko
- University Hospital Dubrava, Department of Psychiatry, Refferal Centre of the Ministry of Health and Social Welfare for Stress-related Disorders, Avenija Gojka Suska 6, HR-10000 Zagreb, Croatia
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Hidalgo-Tamola J, Chitaley K. Review type 2 diabetes mellitus and erectile dysfunction. J Sex Med 2008; 6:916-926. [PMID: 19067787 DOI: 10.1111/j.1743-6109.2008.01116.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
INTRODUCTION Diabetes mellitus (DM) is a major risk factor for the development of erectile dysfunction (ED). Although most diabetic ED cases are in patients with type 2 diabetes (T2DM), the majority of basic science studies examining mechanisms of diabetic ED have been conducted in animal models of type 1 diabetes. AIM Recently, however, clinical and laboratory-based studies have uncovered some key underlying factors of T2DM-associated ED, which we have compiled in this review of T2DM ED. MAIN OUTCOME MEASURES The outcomes discussed in this review include major mechanisms underlying T2DM, discussing both clinical and basic science studies. METHODS We conducted an extensive search of pertinent clinical and basic science literature using PUBMED. RESULTS Mechanisms causing ED in T2DM are multifactorial and often lead to resistance to current therapy. Systemic effects of hyperglycemia and hypogonadism contribute to the development of impaired vasodilatory signaling, smooth muscle cell hypercontractility, and veno-occlusive disorder in T2DM ED. CONCLUSIONS Understanding the different causes for ED in T2DM patients may allow targeted therapy for improved erectile function.
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Affiliation(s)
| | - Kanchan Chitaley
- University of Washington-Department of Urology, Seattle, Washington, WA, USA.
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Bekaert B, Cooper ML, Green FR, McNulty H, Pentieva K, Scott JM, Molloy AM, Rayman MP. Effect of selenium status and supplementation with high-selenium yeast on plasma homocysteine and B vitamin concentrations in the UK elderly. Mol Nutr Food Res 2008; 52:1324-33. [DOI: 10.1002/mnfr.200700353] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Double edge redox-implications for the interaction between endogenous thiols and copper ions: In vitro studies. Bioorg Med Chem 2008; 16:9795-803. [PMID: 18926709 DOI: 10.1016/j.bmc.2008.09.068] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Revised: 09/24/2008] [Accepted: 09/26/2008] [Indexed: 11/22/2022]
Abstract
The present study investigated the redox-consequences of the interaction between various endogenous thiols (RSH)-glutathione, cysteine, homocysteine, gamma-glutamyl-cysteine, and cysteinyl-glycine- and Cu(2+) ions, in terms of their free radical-scavenging, ascorbate-oxidizing and O2(*-)-generating properties of the resulting mixtures. Upon a brief incubation (3-30 min) with Cu(2+), the free radical-scavenging properties (towards ABTS(*)(+) and DPPH(*)) and thiol-titratable groups of the RSH added to the mixtures decreased significantly. Remarkably, both effects were only partial, even in the presence of a large molar Cu(2+)-excess, and were unaffected despite increasing the incubation time. At equimolar concentrations, the RSH/Cu(2+) mixtures led to the formation of (EPR paramagnetic) Cu(II)-complexes that were time-stable and ascorbate-reducible, but redox-inactive towards oxygen. In turn, at a slight molar thiol-excess (3:1), the mixtures resulted in the formation of time-stable Cu(I)-complexes (EPR silent) that were unreactive towards ascorbate and oxygen. The only exception was seen for the thiol, glutathione, whose mixture with Cu(2+) mixture displayed a O2(*-)-generating capacity (cytochrome c- and lucigenin-reduction). The data indicate that, depending on their molar ratio, the interaction between Cu(2+) and the tested thiols would give place to mixtures containing either: (i) time-stable and ascorbate-reducible Cu(II)-complexes which display free radical-scavenging properties, or (ii) time-stable but redox-inactive towards oxygen Cu(I)-complexes. Among the latter, the only exception was that of glutathione.
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Onat A, Hergenç G, Küçükdurmaz Z, Can G, Ayhan E, Bulur S. Serum folate is associated with coronary heart disease independently of homocysteine in Turkish men. Clin Nutr 2008; 27:732-9. [DOI: 10.1016/j.clnu.2008.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 06/17/2008] [Accepted: 06/24/2008] [Indexed: 10/21/2022]
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Sundaramoorthy E, Maiti S, Brahmachari SK, Sengupta S. Predicting protein homocysteinylation targets based on dihedral strain energy and pKa of cysteines. Proteins 2008; 71:1475-83. [PMID: 18076028 DOI: 10.1002/prot.21846] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A multitude of complex diseases have been linked to elevated homocysteine levels; however, till date there is no plausible explanation for a single amino acid's involvement in so many diseases. Since homocysteine is a reactive thiol amino acid and the majority of plasma homocysteine is protein thiol bound, we hypothesized that homocysteine might bind to accessible cysteine residues in target proteins, thereby modulating its structure or function or both. The parameters that dictate homocysteine-protein interaction are not well understood, and the few known homocysteine binding proteins were identified by a candidate protein approach. In this study, we identified potential homocysteine interacting proteins based on cysteine content, solvent accessibility of cysteine residues, and dihedral strain energies and pKa of these cysteines. Pathway mapping of the cysteine-rich proteins revealed that proteins in the coagulation cascade, notch receptor-mediated signaling, LDL endocytosis, programmed cell death, and extracellular matrix proteins were significantly over-represented with cysteine-rich proteins, and we believe that homocysteine has a high probability to bind to proteins in these pathways. In fact, several clinical studies have implicated high homocysteine levels to be associated with diseases like thrombosis, neural tube defects, and so forth, which result from dysfunction of one or more of the proteins identified in our study. Further, we successfully validated our prediction parameters on the proteins that have already been experimentally shown to bind homocysteine, and our structural analysis argues a plausible explanation for these prior reported protein interactions with homocysteine that could not be previously explained.
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Affiliation(s)
- Elayanambi Sundaramoorthy
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, Delhi 110007, India
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31
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Jakubowski H. The molecular basis of homocysteine thiolactone-mediated vascular disease. Clin Chem Lab Med 2008; 45:1704-16. [PMID: 17937605 DOI: 10.1515/cclm.2007.338] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Accumulating evidence suggests that a metabolite of homocysteine (Hcy), the thioester Hcy-thiolactone, plays an important role in atherogenesis and thrombosis. Hcy-thiolactone levels are elevated in hyperhomocysteinemic humans and mice. The thioester chemistry of Hcy-thiolactone underlies its ability to form isopeptide bonds with protein lysine residues, which impairs or alters the protein's function. Protein targets for the modification by Hcy-thiolactone in human blood include fibrinogen, low-density lipoprotein, and high-density lipoprotein. Protein N-homocysteinylation leads to pathophysiological responses, including increased susceptibility to thrombogenesis caused by N-Hcy-fibrinogen, and an autoimmune response elicited by N-Hcy-proteins. Chronic activation of these responses in hyperhomocysteinemia over many years could lead to vascular disease. This article reviews recent evidence supporting the hypothesis that Hcy-thiolactone contributes to pathophysiological effects of Hcy on the vascular system.
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Affiliation(s)
- Hieronim Jakubowski
- Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, International Center for Public Health, Newark, NJ 07101-1709, USA.
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32
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Thampi P, Stewart BW, Joseph L, Melnyk SB, Hennings LJ, Nagarajan S. Dietary homocysteine promotes atherosclerosis in apoE-deficient mice by inducing scavenger receptors expression. Atherosclerosis 2008; 197:620-9. [DOI: 10.1016/j.atherosclerosis.2007.09.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 08/20/2007] [Accepted: 09/04/2007] [Indexed: 10/22/2022]
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33
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Leclerc D, Rozen R. Endoplasmic reticulum stress increases the expression of methylenetetrahydrofolate reductase through the IRE1 transducer. J Biol Chem 2007; 283:3151-3160. [PMID: 18065414 DOI: 10.1074/jbc.m708598200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Methylenetetrahydrofolate reductase (MTHFR), an enzyme in folate and homocysteine metabolism, influences many cellular processes including methionine and nucleotide synthesis, methylation reactions, and maintenance of homocysteine at nontoxic levels. Mild deficiency of MTHFR is common in many populations and modifies risk for several complex traits including vascular disease, birth defects, and cancer. We recently demonstrated that MTHFR can be up-regulated by NF-kappaB, an important mediator of cell survival that is activated by endoplasmic reticulum (ER) stress. This observation, coupled with the reports that homocysteine can induce ER stress, prompted us to examine the possible regulation of MTHFR by ER stress. We found that several well characterized stress inducers (tunicamycin, thapsigargin, and A23187) as well as homocysteine could increase Mthfr mRNA and protein in Neuro-2a cells. The induction of MTHFR was also observed after overexpression of inositol-requiring enzyme-1 (IRE1) and was inhibited by a dominant-negative mutant of IRE1. Because IRE1 triggers c-Jun signaling, we examined the possible involvement of c-Jun in up-regulation of MTHFR. Transfection of c-Jun and two activators of c-Jun (LiCl and sodium valproate) increased MTHFR expression, whereas a reported inhibitor of c-Jun (SP600125) and a dominant-negative derivative of c-Jun N-terminal kinase-1 reduced MTHFR activation. We conclude that ER stress increases MTHFR expression and that IRE1 and c-Jun mediate this activation. These findings provide a novel mechanism by which the ER can regulate homeostasis and allude to an important role for MTHFR in cell survival.
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Affiliation(s)
- Daniel Leclerc
- Departments of Human Genetics and Pediatrics, McGill University Health Center-Montreal Children's Hospital, Montreal H3Z 2Z3, Canada
| | - Rima Rozen
- Departments of Human Genetics and Pediatrics, McGill University Health Center-Montreal Children's Hospital, Montreal H3Z 2Z3, Canada.
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34
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Yi F, Li PL. Mechanisms of homocysteine-induced glomerular injury and sclerosis. Am J Nephrol 2007; 28:254-64. [PMID: 17989498 DOI: 10.1159/000110876] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 09/13/2007] [Indexed: 12/25/2022]
Abstract
Hyperhomocysteinemia (hHcys) has been recognized as a critical risk or pathogenic factor in the progression of end-stage renal disease (ESRD) and in the development of cardiovascular complications related to ESRD. Recently, evidence is accumulating that hHcys may directly act on glomerular cells to induce glomerular dysfunction and consequent glomerular sclerosis, leading to ESRD. In this review, we summarize recent findings that reveal the contribution of homocysteine as a pathogenic factor to the development of glomerular sclerosis or ESRD. In addition, we discuss several important mechanisms mediating the pathogenic action of homocysteine in the glomeruli or in the kidney, such as local oxidative stress, endoplasmic reticulum stress, homocysteinylation, and hypomethylation. Understanding these mechanisms may help design new approaches to develop therapeutic strategies for treatment of hHcys-associated end-organ damage and for prevention of deterioration of kidney function and ultimate ESRD in patients with hypertension and diabetes mellitus or even in aged people with hHcys.
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Affiliation(s)
- Fan Yi
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, USA
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35
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Abstract
Hyperhomocysteinemia is a risk factor for cardiovascular disease, stroke, and thrombosis. Several animal models of hyperhomocysteinemia have been developed by using both dietary and genetic approaches. These animal models have provided considerable insight into the mechanisms underlying the adverse vascular effects of hyperhomocysteinemia. Accumulating evidence suggests a significant role of altered cellular redox reactions in the vascular phenotype of hyperhomocysteinemia. Redox effects of hyperhomocysteinemia are particularly important in mediating the adverse effects of hyperhomocysteinemia on the endothelium, leading to loss of endothelium-derived nitric oxide and vasomotor dysfunction. Redox reactions also may be key factors in the development of vascular hypertrophy, thrombosis, and atherosclerosis in hyperhomocysteinemic animals. In this review, we summarize the metabolic relations between homocysteine and the cellular redox state, the vascular phenotypes that have been observed in hyperhomocysteinemic animals, the evidence for altered redox reactions in vascular tissue, and the specific redox reactions that may mediate the vascular effects of hyperhomocysteinemia.
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Affiliation(s)
- Sanjana Dayal
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
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36
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Cacciapuoti G, Manna C, Napoli D, Zappia V, Porcelli M. Homocysteine-induced endothelial cell adhesion is related to adenosine lowering and is not mediated byS-adenosylhomocysteine. FEBS Lett 2007; 581:4567-70. [PMID: 17850795 DOI: 10.1016/j.febslet.2007.08.042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 08/02/2007] [Accepted: 08/03/2007] [Indexed: 11/24/2022]
Abstract
Hyperhomocysteinemia is a cardiovascular risk factor and may contribute to the pathogenesis of atherosclerosis by altering endothelial functions. The mechanism of homocysteine-induced cell adhesion has been here investigated using EA.hy 926 cells. Homocysteine induces a stereospecific, time- and dose-dependent cell adhesion which is prevented by adenosine. The dramatic increase of S-adenosylhomocysteine induced by adenosine-2',3'-dialdehyde does not cause cell adhesion, indicating that no apparent relationship exists between this process and intracellular S-adenosylhomocysteine content. Homocysteine-induced cell adhesion is abolished by pre-treatment with adenosine-2',3'-dialdehyde, demonstrating that the adenosine depletion caused by reversal of S-adenosylhomocysteine hydrolase reaction is responsible for homocysteine-induced cell damage.
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Affiliation(s)
- Giovanna Cacciapuoti
- Dipartimento di Biochimica e Biofisica, F. Cedrangolo, Seconda Università di Napoli, Naples, Italy.
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37
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Abstract
The nature of the mechanisms underlying the age-related decline in glutathione (GSH) synthetic capacity is at present unclear. Steady-state kinetic parameters of mouse liver GCL (glutamate-cysteine ligase), the rate-limiting enzyme in GSH synthesis, and levels of hepatic GSH synthesis precursors from the trans-sulfuration pathway, such as homocysteine, cystathionine and cysteine, were compared between young and old C57BL/6 mice (6- and 24-month-old respectively). There were no agerelated differences in GCL V(max), but the apparent K(m) for its substrates, cysteine and glutamate, was higher in the old mice compared with the young mice (approximately 800 compared with approximately 300 microM, and approximately 710 compared with 450 microM, P<0.05 for cysteine and glutamate in young and old mice respectively). Amounts of cysteine, cystathionine and Cys-Gly increased with age by 91, 24 and 28% respectively. Glutathione (GSH) levels remained unchanged with age, whereas GSSG content showed an 84% increase, suggesting a significant pro-oxidizing shift in the 2GSH/GSSG ratio. The amount of the toxic trans-sulfuration/glutathione biosynthetic pathway intermediate, homocysteine, was 154% higher (P<0.005) in the liver of old mice compared with young mice. The conversion of homocysteine into cystathionine, a rate-limiting step in trans-sulfuration catalysed by cystathionine beta-synthase, was comparatively less efficient in the old mice, as indicated by cystathionine/homocysteine ratios. Incubation of tissue homogenates with physiological concentrations of homocysteine caused an up to 4.4-fold increase in the apparent K(m) of GCL for its glutamate substrate, but had no effect on V(max). The results suggest that perturbation of the catalytic efficiency of GCL and accumulation of homocysteine from the trans-sulfuration pathway may adversely affect de novo GSH synthesis during aging.
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Affiliation(s)
- Dikran Toroser
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089-9121, U.S.A
| | - Rajindar S. Sohal
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089-9121, U.S.A
- To whom correspondence should be addressed (email )
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38
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Ueland PM, Clarke R. Homocysteine and cardiovascular risk: considering the evidence in the context of study design, folate fortification, and statistical power. Clin Chem 2007; 53:807-9. [PMID: 17468406 DOI: 10.1373/clinchem.2007.085480] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Perła-Kaján J, Twardowski T, Jakubowski H. Mechanisms of homocysteine toxicity in humans. Amino Acids 2007; 32:561-72. [PMID: 17285228 DOI: 10.1007/s00726-006-0432-9] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 06/30/2006] [Indexed: 12/01/2022]
Abstract
Homocysteine, a non-protein amino acid, is an important risk factor for ischemic heart disease and stroke in humans. This review provides an overview of homocysteine influence on endothelium function as well as on protein metabolism with a special respect to posttranslational modification of protein with homocysteine thiolactone. Homocysteine is a pro-thrombotic factor, vasodilation impairing agent, pro-inflammatory factor and endoplasmatic reticulum-stress inducer. Incorporation of Hcy into protein via disulfide or amide linkages (S-homocysteinylation or N-homocysteinylation) affects protein structure and function. Protein N-homocysteinylation causes cellular toxicity and elicits autoimmune response, which may contribute to atherogenesis.
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Affiliation(s)
- J Perła-Kaján
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland.
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40
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Barbato JC, Catanescu O, Murray K, DiBello PM, Jacobsen DW. Targeting of metallothionein by L-homocysteine: a novel mechanism for disruption of zinc and redox homeostasis. Arterioscler Thromb Vasc Biol 2006; 27:49-54. [PMID: 17082481 PMCID: PMC2849140 DOI: 10.1161/01.atv.0000251536.49581.8a] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE L-homocysteine and/or L-homocystine interact in vivo with albumin and other extracellular proteins by forming mixed-disulfide conjugates. Because of its extremely rich cysteine content, we hypothesized that metallothionein, a ubiquitous intracellular zinc-chaperone and superoxide anion radical scavenger, reacts with L-homocysteine and that homocysteinylated-metallothionein suffers loss of function. METHODS AND RESULTS 35S-homocysteinylated-metallothionein was resolved in lysates of cultured human aortic endothelial cells in the absence and presence of reduced glutathione by SDS-PAGE and identified by Western blotting and phosphorimaging. Using zinc-Sepharose chromatography, L-homocysteine was shown to impair the zinc-binding capacity of metallothionein even in the presence of reduced glutathione. L-Homocysteine induced a dose-dependent increase in intracellular free zinc in zinquin-loaded human aortic endothelial cells within 30 minutes, followed by the appearance of early growth response protein-1 within 60 minutes. In addition, intracellular reactive oxygen species dramatically increased 6 hours after L-homocysteine treatment. In vitro studies demonstrated that L-homocysteine is a potent inhibitor of the superoxide anion radical scavenging ability of metallothionein. CONCLUSIONS These studies provide the first evidence that L-homocysteine targets intracellular metallothionein by forming a mixed-disulfide conjugate and that loss of function occurs after homocysteinylation. The data support a novel mechanism for disruption of zinc and redox homeostasis.
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Affiliation(s)
- John C Barbato
- Department Cell Biology, Lerner Research Institute, The Cleveland Clinic, Cleveland, OH 44195, USA
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41
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Hortin GL, Seam N, Hoehn GT. Bound homocysteine, cysteine, and cysteinylglycine distribution between albumin and globulins. Clin Chem 2006; 52:2258-64. [PMID: 17068168 DOI: 10.1373/clinchem.2006.074302] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Major portions of homocysteine (Hcy), cysteine (Cys), cysteinylglycine (CysGly), and glutathione in serum are covalently bound to proteins via disulfides. Albumin has been considered the dominant binding protein. METHODS Pooled serum and plasma from healthy adults were fractionated into albumin and globulins by affinity columns. Content of Hcy, Cys, CysGly, and glutathione was determined for serum and plasma fractions and purified proteins by an HPLC method before and after incubation with excess CysGly, Hcy, or glutathione RESULTS Of protein-bound amino acids in pooled serum, 12% of Hcy, 21% of Cys, and 33% of CysGly were bound to globulins, with the remainder bound to albumin. Slightly higher proportions were bound to globulins in pooled plasma. Globulins had approximately 16% of total exchangeable disulfide and thiol groups in serum based on results of loading with CysGly. These results agree with expected abundance of unpaired Cys residues in globulins relative to albumin. Significant amounts of disulfide-linked amino acids were detected for HDL and alpha1-acid glycoprotein but not for transferrin. Exchange of disulfide-linked amino acids on exposure to excess Hcy or glutathione was much faster for albumin than for alpha1-acid glycoprotein. CONCLUSIONS Approximately 10%-30%, of protein-bound Hcy, Cys, and CysGly are disulfide-linked to globulins. Amino acids disulfide-linked to albumin are rapidly exchangeable, while exchange of disulfide-linked amino acids from globulins, such as alpha1-acid glycoprotein, is much slower. Consequently, the pools of Hcy, Cys, and CysGly bound to albumin and globulin may represent kinetically and functionally distinct pools. Plasma concentrations of total Hcy and Cys, which are dominated by albumin-bound pools, may not reflect the abundance of functionally significant modifications of globulins.
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Affiliation(s)
- Glen L Hortin
- Department of Laboratory Medicine, Warren Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
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Refsum H, Nurk E, Smith AD, Ueland PM, Gjesdal CG, Bjelland I, Tverdal A, Tell GS, Nygård O, Vollset SE. The Hordaland Homocysteine Study: a community-based study of homocysteine, its determinants, and associations with disease. J Nutr 2006; 136:1731S-1740S. [PMID: 16702348 DOI: 10.1093/jn/136.6.1731s] [Citation(s) in RCA: 351] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Hordaland Homocysteine Study (HHS) is a population-based study of more than 18,000 men and women in the county of Hordaland in Western Norway. The first investigation (HHS-I) took place in 1992-93, when the subjects were aged 40-67 y. In 1997-99, a follow-up study (HHS-II) of 7,053 subjects was carried out. In this large population, plasma levels of total homocysteine (tHcy) are associated with several physiologic and lifestyle factors and common diseases. Increasing age, male sex, smoking, coffee consumption, high blood pressure, unfavorable lipid profile, high creatinine, and the MTHFR 677C > T polymorphism are among the factors associated with increased tHcy levels; physical activity, moderate alcohol consumption, and a good folate or vitamin B-12 status are associated with lower tHcy levels. Subjects with raised tHcy levels have increased risk of cardiovascular morbidity, cardiovascular and noncardiovascular mortality, and are more likely to suffer from depression and from cognitive deficit (elderly). Among women, raised tHcy levels are associated with decreased bone mineral density and increased risk of osteoporosis. Women with raised tHcy levels also have an increased risk of having suffered from pregnancy complications and an adverse pregnancy outcome. Significant associations between tHcy and clinical outcomes are usually observed for tHcy levels > 15 micromol/L, but for most conditions, there is a continuous concentration-response relation with no apparent threshold concentration. Overall, the findings from HHS indicate that a raised tHcy level is associated with multiple clinical conditions, whereas a low tHcy level is associated with better physical and mental health.
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Affiliation(s)
- Helga Refsum
- Norwegian Institute of Public Health, Oslo, Norway.
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43
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Abstract
Hyperhomocysteinemia, an independent, modifiable risk factor for cardiovascular disease, is found in most patients with end-stage renal disease. In this issue, Perna et al. examine the extent of protein-S-linked and protein-N-linked homocysteinylation in uremic patients on hemodialysis and the effect of folate treatment on protein homocysteinylation. Their findings show that protein-N-linked homocysteinylation, but not S-linked homocysteinylation, can be normalized by folate therapy.
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Affiliation(s)
- D W Jacobsen
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
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