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Dufault RJ, Crider RA, Deth RC, Schnoll R, Gilbert SG, Lukiw WJ, Hitt AL. Higher rates of autism and attention deficit/hyperactivity disorder in American children: Are food quality issues impacting epigenetic inheritance? World J Clin Pediatr 2023; 12:25-37. [PMID: 37034430 PMCID: PMC10075020 DOI: 10.5409/wjcp.v12.i2.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 12/25/2022] [Accepted: 01/10/2023] [Indexed: 03/06/2023] Open
Abstract
In the United States, schools offer special education services to children who are diagnosed with a learning or neurodevelopmental disorder and have difficulty meeting their learning goals. Pediatricians may play a key role in helping children access special education services. The number of children ages 6-21 in the United States receiving special education services increased 10.4% from 2006 to 2021. Children receiving special education services under the autism category increased 242% during the same period. The demand for special education services for children under the developmental delay and other health impaired categories increased by 184% and 83% respectively. Although student enrollment in American schools has remained stable since 2006, the percentage distribution of children receiving special education services nearly tripled for the autism category and quadrupled for the developmental delay category by 2021. Allowable heavy metal residues remain persistent in the American food supply due to food ingredient manufacturing processes. Numerous clinical trial data indicate heavy metal exposures and poor diet are the primary epigenetic factors responsible for the autism and attention deficit hyperactivity disorder epidemics. Dietary heavy metal exposures, especially inorganic mercury and lead may impact gene behavior across generations. In 2021, the United States Congress found heavy metal residues problematic in the American food supply but took no legislative action. Mandatory health warning labels on select foods may be the only way to reduce dietary heavy metal exposures and improve child learning across generations.
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Affiliation(s)
- Renee J Dufault
- Department of Research, Food Ingredient and Health Research Institute, Naalehu, HI 96772, United States
- College of Graduate Health Studies, A.T. Still University, Kirksville, MO 63501, United States
| | - Raquel A Crider
- Department of Research, Food Ingredient and Health Research Institute, Naalehu, HI 96772, United States
| | - Richard C Deth
- Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, FL 33314, United States
| | - Roseanne Schnoll
- Department of Research, Food Ingredient and Health Research Institute, Naalehu, HI 96772, United States
- Department of Health and Nutrition Sciences, Brooklyn College of CUNY, Brooklyn, NY 11210, United States
| | - Steven G Gilbert
- Department of Research, Food Ingredient and Health Research Institute, Naalehu, HI 96772, United States
- Department of Research, Institute of Neurotoxicology and Neurological Disorders, Seattle, WA 98105, United States
| | - Walter J Lukiw
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112, United States
| | - Amanda L Hitt
- Food Integrity Campaign, Government Accountability Project, Columbia, WA 20006, United States
- Department of Legal, Food Ingredient and Health Research Institute, Naalehu, HI 96772, United States
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Offringa AK, Bourgonje AR, Schrier MS, Deth RC, van Goor H. Clinical implications of vitamin B 12 as redox-active cofactor. Trends Mol Med 2021; 27:931-934. [PMID: 34312076 DOI: 10.1016/j.molmed.2021.07.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/30/2021] [Accepted: 07/02/2021] [Indexed: 10/20/2022]
Abstract
Vitamin B12 is a redox-active compound containing a cobalt atom that cycles between oxidation states. Superoxide scavenging induces its oxidation, disabling activation of the enzymes methionine synthase and methylmalonyl-CoA mutase, disrupting gene expression and energy production. High-dosed vitamin B12 may be clinically used to reduce oxidative stress and preserve cofactor functions.
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Affiliation(s)
- Annette K Offringa
- Microbiology and System Biology, Netherlands Organization for Applied Scientific Research, The Hague, The Netherlands
| | - Arno R Bourgonje
- Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Matthew S Schrier
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Richard C Deth
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Harry van Goor
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
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Karhu E, Zukerman R, Eshraghi RS, Mittal J, Deth RC, Castejon AM, Trivedi M, Mittal R, Eshraghi AA. Nutritional interventions for autism spectrum disorder. Nutr Rev 2019; 78:515-531. [DOI: 10.1093/nutrit/nuz092] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
AbstractAutism spectrum disorder (ASD) is an increasingly prevalent neurodevelopmental disorder with considerable clinical heterogeneity. With no cure for the disorder, treatments commonly center around speech and behavioral therapies to improve the characteristic social, behavioral, and communicative symptoms of ASD. Gastrointestinal disturbances are commonly encountered comorbidities that are thought to be not only another symptom of ASD but to also play an active role in modulating the expression of social and behavioral symptoms. Therefore, nutritional interventions are used by a majority of those with ASD both with and without clinical supervision to alleviate gastrointestinal and behavioral symptoms. Despite a considerable interest in dietary interventions, no consensus exists regarding optimal nutritional therapy. Thus, patients and physicians are left to choose from a myriad of dietary protocols. This review, summarizes the state of the current clinical and experimental literature on nutritional interventions for ASD, including gluten-free and casein-free, ketogenic, and specific carbohydrate diets, as well as probiotics, polyunsaturated fatty acids, and dietary supplements (vitamins A, C, B6, and B12; magnesium and folate).
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Affiliation(s)
- Elisa Karhu
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Ryan Zukerman
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Rebecca S Eshraghi
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida, USA
- Division of Gastroenterology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, Florida, USA
- Department of Neurological Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Jeenu Mittal
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Richard C Deth
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida, USA
| | - Ana M Castejon
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida, USA
| | - Malav Trivedi
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida, USA
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Padmanabhan S, Waly MI, Taranikanti V, Guizani N, Ali A, Rahman MS, Al-Attabi Z, Al-Malky RN, Al-Maskari SNM, Al-Ruqaishi BRS, Dong J, Deth RC. Folate/Vitamin B12 Supplementation Combats Oxidative Stress-Associated Carcinogenesis in a Rat Model of Colon Cancer. Nutr Cancer 2018; 71:100-110. [DOI: 10.1080/01635581.2018.1513047] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Smitha Padmanabhan
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| | - Mostafa I. Waly
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
- Department of Nutrition, High Institute of Public Health, Alexandria, Egypt
| | - Varna Taranikanti
- Department of Human and Clinical Anatomy, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Nejib Guizani
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| | - Amanat Ali
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| | - Mohammad S. Rahman
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| | - Zaher Al-Attabi
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| | - Raya N. Al-Malky
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| | - Sultan N. M. Al-Maskari
- Small Animal House, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Bader R. S. Al-Ruqaishi
- Small Animal House, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Jianan Dong
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida, USA
| | - Richard C. Deth
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida, USA
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Eshraghi RS, Deth RC, Mittal R, Aranke M, Kay SIS, Moshiree B, Eshraghi AA. Early Disruption of the Microbiome Leading to Decreased Antioxidant Capacity and Epigenetic Changes: Implications for the Rise in Autism. Front Cell Neurosci 2018; 12:256. [PMID: 30158857 PMCID: PMC6104136 DOI: 10.3389/fncel.2018.00256] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 07/27/2018] [Indexed: 12/20/2022] Open
Abstract
Currently, 1 out of every 59 children in the United States is diagnosed with autism. While initial research to find the possible causes for autism were mostly focused on the genome, more recent studies indicate a significant role for epigenetic regulation of gene expression and the microbiome. In this review article, we examine the connections between early disruption of the developing microbiome and gastrointestinal tract function, with particular regard to susceptibility to autism. The biological mechanisms that accompany individuals with autism are reviewed in this manuscript including immune system dysregulation, inflammation, oxidative stress, metabolic and methylation abnormalities as well as gastrointestinal distress. We propose that these autism-associated biological mechanisms may be caused and/or sustained by dysbiosis, an alteration to the composition of resident commensal communities relative to the community found in healthy individuals and its redox and epigenetic consequences, changes that in part can be due to early use and over-use of antibiotics across generations. Further studies are warranted to clarify the contribution of oxidative stress and gut microbiome in the pathophysiology of autism. A better understanding of the microbiome and gastrointestinal tract in relation to autism will provide promising new opportunities to develop novel treatment modalities.
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Affiliation(s)
- Rebecca S. Eshraghi
- Division of Gastroenterology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Richard C. Deth
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL, United States
| | - Rahul Mittal
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Mayank Aranke
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Sae-In S. Kay
- Dr. Kiran C. Patel College of Osteopathic Medicine, Nova Southeastern University, Fort Lauderdale, FL, United States
| | - Baharak Moshiree
- Division of Gastroenterology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Adrien A. Eshraghi
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, United States
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Terhune TD, Deth RC. Aluminum Adjuvant-Containing Vaccines in the Context of the Hygiene Hypothesis: A Risk Factor for Eosinophilia and Allergy in a Genetically Susceptible Subpopulation? Int J Environ Res Public Health 2018; 15:E901. [PMID: 29751492 PMCID: PMC5981940 DOI: 10.3390/ijerph15050901] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/19/2018] [Accepted: 04/29/2018] [Indexed: 12/17/2022]
Abstract
There are similarities between the immune response following immunization with aluminum adjuvants and the immune response elicited by some helminthic parasites, including stimulation of immunoglobulin E (IgE) and eosinophilia. Immunization with aluminum adjuvants, as with helminth infection, induces a Th2 type cell mediated immune response, including eosinophilia, but does not induce an environment conducive to the induction of regulatory mechanisms. Helminths play a role in what is known as the hygiene hypothesis, which proposes that decreased exposure to microbes during a critical time in early life has resulted in the increased prevalence and morbidity of asthma and atopic disorders over the past few decades, especially in Western countries. In addition, gut and lung microbiome composition and their interaction with the immune system plays an important role in a properly regulated immune system. Disturbances in microbiome composition are a risk factor for asthma and allergies. We propose that immunization with aluminum adjuvants in general is not favorable for induction of regulatory mechanisms and, in the context of the hygiene hypothesis and microbiome theory, can be viewed as an amplifying factor and significant contributing risk factor for allergic diseases, especially in a genetically susceptible subpopulation.
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Affiliation(s)
- Todd D Terhune
- College of Pharmacy, Department of Pharmaceutical Sciences, Nova Southeastern University, 1382 Terry Bldg, 3200 South University Drive, Fort Lauderdale, FL 33328, USA.
| | - Richard C Deth
- College of Pharmacy, Department of Pharmaceutical Sciences, Nova Southeastern University, 1382 Terry Bldg, 3200 South University Drive, Fort Lauderdale, FL 33328, USA.
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Kern JK, Geier DA, Deth RC, Sykes LK, Hooker BS, Love JM, Bjørklund G, Chaigneau CG, Haley BE, Geier MR. RETRACTED ARTICLE: Systematic Assessment of Research on Autism Spectrum Disorder and Mercury Reveals Conflicts of Interest and the Need for Transparency in Autism Research. Sci Eng Ethics 2017; 23:1689-1690. [PMID: 26507205 PMCID: PMC5705728 DOI: 10.1007/s11948-015-9713-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/19/2015] [Indexed: 06/05/2023]
Affiliation(s)
- Janet K. Kern
- Institute of Chronic Illnesses, Inc., 14 Redgate Court, Silver Spring, MD 20905 USA
| | - David A. Geier
- Institute of Chronic Illnesses, Inc., 14 Redgate Court, Silver Spring, MD 20905 USA
| | | | | | | | | | - Geir Bjørklund
- Council for Nutritional and Environmental Medicine, Mo i Rana, Norway
| | | | | | - Mark R. Geier
- Institute of Chronic Illnesses, Inc., 14 Redgate Court, Silver Spring, MD 20905 USA
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Kern JK, Geier DA, Deth RC, Sykes LK, Hooker BS, Love JM, Bjørklund G, Chaigneau CG, Haley BE, Geier MR. Systematic Assessment of Research on Autism Spectrum Disorder (ASD) and Mercury Reveals Conflicts of Interest and the Need for Transparency in Autism Research. Sci Eng Ethics 2017; 23:1691-1718. [PMID: 29119411 PMCID: PMC5705731 DOI: 10.1007/s11948-017-9983-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Historically, entities with a vested interest in a product that critics have suggested is harmful have consistently used research to back their claims that the product is safe. Prominent examples are: tobacco, lead, bisphenol A, and atrazine. Research literature indicates that about 80-90% of studies with industry affiliation found no harm from the product, while only about 10-20% of studies without industry affiliation found no harm. In parallel to other historical debates, recent studies examining a possible relationship between mercury (Hg) exposure and autism spectrum disorder (ASD) show a similar dichotomy. Studies sponsored and supported by industry or entities with an apparent conflict of interest have most often shown no evidence of harm or no "consistent" evidence of harm, while studies without such affiliations report positive evidence of a Hg/autism association. The potentially causal relationship between Hg exposure and ASD differs from other toxic products since there is a broad coalition of entities for whom a conflict of interest arises. These include influential governmental public health entities, the pharmaceutical industry, and even the coal burning industry. This review includes a systematic literature search of original studies on the potential relationship between Hg and ASD from 1999 to August 2015, finding that of the studies with public health and/or industry affiliation, 86% reported no relationship between Hg and ASD. However, among studies without public health and/or industry affiliation, only 21% find no relationship between Hg and ASD. The discrepancy in these results suggests a bias indicative of a conflict of interest.
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Affiliation(s)
- Janet K. Kern
- Institute of Chronic Illnesses, Inc, 14 Redgate Court, Silver Spring, MD 20905 USA
| | - David A. Geier
- Institute of Chronic Illnesses, Inc, 14 Redgate Court, Silver Spring, MD 20905 USA
| | | | | | | | | | - Geir Bjørklund
- Council for Nutritional and Environmental Medicine, Mo i Rana, Norway
| | | | | | - Mark R. Geier
- Institute of Chronic Illnesses, Inc, 14 Redgate Court, Silver Spring, MD 20905 USA
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Zhang Y, Hodgson NW, Trivedi MS, Abdolmaleky HM, Fournier M, Cuenod M, Do KQ, Deth RC. Decreased Brain Levels of Vitamin B12 in Aging, Autism and Schizophrenia. PLoS One 2016; 11:e0146797. [PMID: 26799654 PMCID: PMC4723262 DOI: 10.1371/journal.pone.0146797] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 12/22/2015] [Indexed: 12/21/2022] Open
Abstract
Many studies indicate a crucial role for the vitamin B12 and folate-dependent enzyme methionine synthase (MS) in brain development and function, but vitamin B12 status in the brain across the lifespan has not been previously investigated. Vitamin B12 (cobalamin, Cbl) exists in multiple forms, including methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), serving as cofactors for MS and methylmalonylCoA mutase, respectively. We measured levels of five Cbl species in postmortem human frontal cortex of 43 control subjects, from 19 weeks of fetal development through 80 years of age, and 12 autistic and 9 schizophrenic subjects. Total Cbl was significantly lower in older control subjects (> 60 yrs of age), primarily reflecting a >10-fold age-dependent decline in the level of MeCbl. Levels of inactive cyanocobalamin (CNCbl) were remarkably higher in fetal brain samples. In both autistic and schizophrenic subjects MeCbl and AdoCbl levels were more than 3-fold lower than age-matched controls. In autistic subjects lower MeCbl was associated with decreased MS activity and elevated levels of its substrate homocysteine (HCY). Low levels of the antioxidant glutathione (GSH) have been linked to both autism and schizophrenia, and both total Cbl and MeCbl levels were decreased in glutamate-cysteine ligase modulatory subunit knockout (GCLM-KO) mice, which exhibit low GSH levels. Thus our findings reveal a previously unrecognized decrease in brain vitamin B12 status across the lifespan that may reflect an adaptation to increasing antioxidant demand, while accelerated deficits due to GSH deficiency may contribute to neurodevelopmental and neuropsychiatric disorders.
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Affiliation(s)
- Yiting Zhang
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, United States of America
| | - Nathaniel W. Hodgson
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, United States of America
- Department of Surgery, Laboratory of Nutrition and Metabolism at BIDMC, Harvard Medical School, Boston, MA, 02215, United States of America
| | - Malav S. Trivedi
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, United States of America
- Department of Pharmaceutical Sciences, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, 33328, United States of America
| | - Hamid M. Abdolmaleky
- Department of Medicine (Biomedical Genetics Section), Genetics & Genomics, Boston University School of Medicine, Boston, MA, 02118, United States of America
| | - Margot Fournier
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Lausanne, Switzerland
| | - Michel Cuenod
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Lausanne, Switzerland
| | - Kim Quang Do
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Lausanne, Switzerland
| | - Richard C. Deth
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, United States of America
- Department of Pharmaceutical Sciences, Nova Southeastern University College of Pharmacy, Fort Lauderdale, FL, 33328, United States of America
- * E-mail:
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Trivedi MS, Hodgson NW, Walker SJ, Trooskens G, Nair V, Deth RC. Epigenetic effects of casein-derived opioid peptides in SH-SY5Y human neuroblastoma cells. Nutr Metab (Lond) 2015; 12:54. [PMID: 26664459 PMCID: PMC4673759 DOI: 10.1186/s12986-015-0050-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Accepted: 12/03/2015] [Indexed: 12/18/2022] Open
Abstract
Background Casein-free, gluten-free diets have been reported to mitigate some of the inflammatory gastrointestinal and behavioral traits associated with autism, but the mechanism for this palliative effect has not been elucidated. We recently showed that the opioid peptide beta-casomorphin-7, derived from bovine (bBCM7) milk, decreases cysteine uptake, lowers levels of the antioxidant glutathione (GSH) and decreases the methyl donor S-adenosylmethionine (SAM) in both Caco-2 human GI epithelial cells and SH-SY5Y human neuroblastoma cells. While human breast milk can also release a similar peptide (hBCM-7), the bBCM7 and hBCM-7 vary greatly in potency; as the bBCM-7 is highly potent and similar to morphine in it's effects. Since SAM is required for DNA methylation, we wanted to further investigate the epigenetic effects of these food-derived opioid peptides. In the current study the main objective was to characterize functional pathways and key genes responding to DNA methylation effects of food-derived opioid peptides. Methods SH-SY5Y neuroblastoma cells were treated with 1 μM hBCM7 and bBCM7 and RNA and DNA were isolated after 4 h with or without treatment. Transcriptional changes were assessed using a microarray approach and CpG methylation status was analyzed at 450,000 CpG sites. Functional implications from both endpoints were evaluated via Ingenuity Pathway Analysis 4.0 and KEGG pathway analysis was performed to identify biological interactions between transcripts that were significantly altered at DNA methylation or transcriptional levels (p < 0.05, FDR <0.1). Results Here we show that hBCM7 and bBCM7, as well as morphine, cause epigenetic changes affecting gene pathways related to gastrointestinal disease and inflammation. These epigenetic consequences exhibited the same potency order as opiate inhibition of cysteine uptake insofar as hBCM7 was less potent than bBCM7, which was less potent than morphine. Conclusion Our findings indicate that epigenetic effects of milk-derived opiate peptides may contribute to GI dysfunction and inflammation in sensitive individuals. While the current study was performed using SH-SY5Y neuronal cellular models, similar actions on other cells types might combine to cause symptoms of intolerance. These actions may provide a potential contributing mechanism for the beneficial effects of a casein-free diet in alleviating gastrointestinal symptoms in neurological conditions including autism and other conditions. Lastly, our study also contributes to the evolving awareness of a “gut-brain connection”. Electronic supplementary material The online version of this article (doi:10.1186/s12986-015-0050-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Malav S Trivedi
- Department of Pharmaceutical Sciences, Nova Southeastern University, Rm # 3103, HPD building, Fort Lauderdale, FL USA
| | - Nathaniel W Hodgson
- Department of Molecular and Cellular Biology, Harvard Medical School, Boston, MA USA
| | - Stephen J Walker
- Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston Salem, NC USA
| | - Geert Trooskens
- Department of Mathematical Modelling, Statistics and Bioinformatics, University of Ghent, Ghent, Belgium
| | - Vineeth Nair
- Department of Pharmaceutical Sciences, Nova Southeastern University, Rm # 3103, HPD building, Fort Lauderdale, FL USA
| | - Richard C Deth
- Department of Pharmaceutical Sciences, Nova Southeastern University, Rm # 3103, HPD building, Fort Lauderdale, FL USA
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Abstract
OBJECTIVE The objective of this study was to review and compare the similarities between autism spectrum disorder (ASD) and ADHD with regard to symptomatology, neurological deficits, metabolic and endocrine-related conditions, and brain pathology. METHOD A comprehensive review of the relevant research literature was carried out. RESULTS A number of important similarities between ASD and ADHD were identified, including recent increases in prevalence, male-biased incidence, shared involvement of sensory processing, motor and impulse control, abnormal patterns of neural connectivity, and sleep disturbances. Studies suggest involvement of androgen metabolism, impaired methylation, and heavy metal toxicity as possible contributing factors for both disorders. CONCLUSION ASD and ADHD share a number of features and pathophysiological conditions, which suggests that the two disorders may be a continuum and have a common origin.
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Affiliation(s)
- Janet K Kern
- Institute of Chronic Illnesses, Inc., Silver Spring, MD, USA University of Texas Southwestern Medical Center at Dallas, TX, USA
| | - David A Geier
- Institute of Chronic Illnesses, Inc., Silver Spring, MD, USA
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12
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Trivedi MS, Shah JS, Al-Mughairy S, Hodgson NW, Simms B, Trooskens GA, Van Criekinge W, Deth RC. Food-derived opioid peptides inhibit cysteine uptake with redox and epigenetic consequences. J Nutr Biochem 2014; 25:1011-8. [PMID: 25018147 DOI: 10.1016/j.jnutbio.2014.05.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 04/07/2014] [Accepted: 05/05/2014] [Indexed: 12/17/2022]
Abstract
Dietary interventions like gluten-free and casein-free diets have been reported to improve intestinal, autoimmune and neurological symptoms in patients with a variety of conditions; however, the underlying mechanism of benefit for such diets remains unclear. Epigenetic programming, including CpG methylation and histone modifications, occurring during early postnatal development can influence the risk of disease in later life, and such programming may be modulated by nutritional factors such as milk and wheat, especially during the transition from a solely milk-based diet to one that includes other forms of nutrition. The hydrolytic digestion of casein (a major milk protein) and gliadin (a wheat-derived protein) releases peptides with opioid activity, and in the present study, we demonstrate that these food-derived proline-rich opioid peptides modulate cysteine uptake in cultured human neuronal and gastrointestinal (GI) epithelial cells via activation of opioid receptors. Decreases in cysteine uptake were associated with changes in the intracellular antioxidant glutathione and the methyl donor S-adenosylmethionine. Bovine and human casein-derived opioid peptides increased genome-wide DNA methylation in the transcription start site region with a potency order similar to their inhibition of cysteine uptake. Altered expression of genes involved in redox and methylation homeostasis was also observed. These results illustrate the potential of milk- and wheat-derived peptides to exert antioxidant and epigenetic changes that may be particularly important during the postnatal transition from placental to GI nutrition. Differences between peptides derived from human and bovine milk may contribute to developmental differences between breastfed and formula-fed infants. Restricted antioxidant capacity, caused by wheat- and milk-derived opioid peptides, may predispose susceptible individuals to inflammation and systemic oxidation, partly explaining the benefits of gluten-free or casein-free diets.
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Affiliation(s)
- Malav S Trivedi
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Jayni S Shah
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Sara Al-Mughairy
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Nathaniel W Hodgson
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Benjamin Simms
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Geert A Trooskens
- Department of Mathematical Modelling, Statistics and Bioinformatics, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Wim Van Criekinge
- Department of Mathematical Modelling, Statistics and Bioinformatics, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Richard C Deth
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA.
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Hodgson NW, Waly MI, Al-Farsi YM, Al-Sharbati MM, Al-Farsi O, Ali A, Ouhtit A, Zang T, Zhou ZS, Deth RC. Decreased glutathione and elevated hair mercury levels are associated with nutritional deficiency-based autism in Oman. Exp Biol Med (Maywood) 2014; 239:697-706. [DOI: 10.1177/1535370214527900] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Genetic, nutrition, and environmental factors have each been implicated as sources of risk for autism. Oxidative stress, including low plasma levels of the antioxidant glutathione, has been reported by numerous autism studies, which can disrupt methylation-dependent epigenetic regulation of gene expression with neurodevelopmental consequences. We investigated the status of redox and methylation metabolites, as well as the level of protein homocysteinylation and hair mercury levels, in autistic and neurotypical control Omani children, who were previously shown to exhibit significant nutritional deficiencies in serum folate and vitamin B12. The serum level of glutathione in autistic subjects was significantly below control levels, while levels of homocysteine and S-adenosylhomocysteine were elevated, indicative of oxidative stress and decreased methionine synthase activity. Autistic males had lower glutathione and higher homocysteine levels than females, while homocysteinylation of serum proteins was increased in autistic males but not females. Mercury levels were markedly elevated in the hair of autistic subjects vs. control subjects, consistent with the importance of glutathione for its elimination. Thus, autism in Oman is associated with decreased antioxidant resources and decreased methylation capacity, in conjunction with elevated hair levels of mercury.
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Affiliation(s)
- Nathaniel W Hodgson
- Department of Pharmaceutical Sciences, Bouve College of Health Sciences, Northeastern University, Boston, MA 02115, USA
| | - Mostafa I Waly
- Department of Food Science and Nutrition, Sultan Qaboos University, P.O.Box 34, P.C. 123, Al-Khoud, Muscat, Sultanate of Oman
- Nutrition Department, High Institute of Public Health, Alexandria University, P.C. 165, El-Hadra, Alexandria, Egypt
| | - Yahya M Al-Farsi
- Department of Family Medicine and Public Health, College of Medicine and Health Sciences, Sultan Qaboos University, P.O.Box 35, P.C. 123, Al-Khoud, Muscat, Sultanate of Oman
- Department of Epidemiology, School of Public Health, Boston University, Boston, MA 02118, USA
| | - Marwan M Al-Sharbati
- Department of Behavioral Medicine, College of Medicine and Health Sciences, Sultan Qaboos University, Al-Khoud 123, Muscat, Sultanate of Oman
| | - Omar Al-Farsi
- Department of Family Medicine and Public Health, College of Medicine and Health Sciences, Sultan Qaboos University, P.O.Box 35, P.C. 123, Al-Khoud, Muscat, Sultanate of Oman
| | - Amanat Ali
- Department of Food Science and Nutrition, Sultan Qaboos University, P.O.Box 34, P.C. 123, Al-Khoud, Muscat, Sultanate of Oman
| | - Allal Ouhtit
- Department of Genetics, College of Medicine and Health Sciences, Sultan Qaboos University, Al-Khoud 123, Muscat, Sultanate of Oman
| | - Tianzhu Zang
- Barnett Institute of Chemical and Biological Analysis, College of Science, Northeastern University, Boston, MA 02115, USA
| | - Zhaohui Sunny Zhou
- Barnett Institute of Chemical and Biological Analysis, College of Science, Northeastern University, Boston, MA 02115, USA
| | - Richard C Deth
- Department of Pharmaceutical Sciences, Bouve College of Health Sciences, Northeastern University, Boston, MA 02115, USA
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Raymond LJ, Deth RC, Ralston NVC. Potential Role of Selenoenzymes and Antioxidant Metabolism in relation to Autism Etiology and Pathology. Autism Res Treat 2014; 2014:164938. [PMID: 24734177 PMCID: PMC3966422 DOI: 10.1155/2014/164938] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 01/07/2014] [Accepted: 01/27/2014] [Indexed: 11/17/2022]
Abstract
Autism and autism spectrum disorders (ASDs) are behaviorally defined, but the biochemical pathogenesis of the underlying disease process remains uncharacterized. Studies indicate that antioxidant status is diminished in autistic subjects, suggesting its pathology is associated with augmented production of oxidative species and/or compromised antioxidant metabolism. This suggests ASD may result from defects in the metabolism of cellular antioxidants which maintain intracellular redox status by quenching reactive oxygen species (ROS). Selenium-dependent enzymes (selenoenzymes) are important in maintaining intercellular reducing conditions, particularly in the brain. Selenoenzymes are a family of ~25 genetically unique proteins, several of which have roles in preventing and reversing oxidative damage in brain and endocrine tissues. Since the brain's high rate of oxygen consumption is accompanied by high ROS production, selenoenzyme activities are particularly important in this tissue. Because selenoenzymes can be irreversibly inhibited by many electrophiles, exposure to these organic and inorganic agents can diminish selenoenzyme-dependent antioxidant functions. This can impair brain development, particularly via the adverse influence of oxidative stress on epigenetic regulation. Here we review the physiological roles of selenoproteins in relation to potential biochemical mechanisms of ASD etiology and pathology.
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Affiliation(s)
- Laura J Raymond
- Energy & Environmental Research Center, University of North Dakota, 15 North 23rd Street, Stop 9018, Grand Forks, ND 58202, USA
| | - Richard C Deth
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Nicholas V C Ralston
- Energy & Environmental Research Center, University of North Dakota, 15 North 23rd Street, Stop 9018, Grand Forks, ND 58202, USA
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Abstract
While autism is still a mysterious developmental disorder, expansion of research efforts over the past 10 to 15 years has yielded a number of important clues implicating both genetic and environmental factors. We can now assert with a measure of confidence that contemporary autism reflects the combined impact of multiple environmental factors on the processes that regulate development in genetically vulnerable individuals. Since epigenetic regulation of gene expression is acknowledged as the most critical factor in development and DNA methylation (the addition of a carbon atom at discrete locations) is the fundamental event for epigenetic regulation, dysfunctional methylation can be considered as a likely cause of autism. Since methylation activity is highly sensitive to oxidative stress (an abnormal redox state) and many environmental factors promote oxidative stress, we have proposed a redox/methylation hypothesis for autism causation. The narrative herein describes the evolution of this hypothesis, which is essentially a series of linked discoveries about how the brain uniquely relies on oxidation and methylation to guide its development and to carry out its cognitive functions.
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Affiliation(s)
- Richard C Deth
- Northeastern University, Boston, Massachusetts, United States
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16
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Al-Farsi YM, Waly MI, Deth RC, Al-Sharbati MM, Al-Shafaee M, Al-Farsi O, Al-Khaduri MM, Al-Adawi S, Hodgson NW, Gupta I, Ouhtit A. Impact of nutrition on serum levels of docosahexaenoic acid among Omani children with autism. Nutrition 2013; 29:1142-6. [PMID: 23800562 DOI: 10.1016/j.nut.2013.03.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 01/08/2023]
Abstract
OBJECTIVES Autism is a lifelong neurodevelopmental disorder of early childhood. Dietary supplementation of the ω-3 fatty acid (docosahexaenoic acid [DHA]) during prenatal and postnatal life is considered a protective dietary intervention strategy to minimize the risk for autism spectrum disorder (ASD). To our knowledge, no relevant studies have been conducted in the Middle East investigating the status of DHA among children with autism during early childhood. The aim of this study was to investigate the serum levels and dietary intake status of DHA among Omani children recently diagnosed with ASD. METHODS The present case-control study involved 80 Omani children (<5 y), 40 cases and 40 controls matched for age and sex. A semi-quantitative food frequency questionnaire was used to assess dietary intake of all the participants, while serum levels of DHA were measured using high-performance liquid chromatography. RESULTS Our results showed that children with ASD had lower dietary consumption of foodstuff containing DHA, as well as lower serum levels of DHA than controls. CONCLUSION The present finding from Oman supports the view of other studies that there are low serum levels of DHA among children with ASD.
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Affiliation(s)
- Yahya M Al-Farsi
- Department of Family Medicine and Public Health, College of Medicine and Health Sciences, Sultan Qaboos University, Al-Khoud, Sultanate of Oman
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Waly MI, Ali BH, Deth RC. Glutathione efficacy as a dietary antioxidant against azoxymethane‐induced colon carcinogenesis in rats. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.861.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mostafa I. Waly
- Food Science and Nutrition DepartmentSultan Qabos UniversityMuscatOman
- Nutrition DepartmentHigh Institute of Public HealthAlexandria UniversityEgypt
| | - Badreldin H Ali
- Pharmacology and Clinical Pharmacy DepartmentSultan Qabos UniversityMuscatOman
| | - Richard C Deth
- Pharmacology DepartmentBouve Collge of Health SciencesNortheastern UniversityBostonMA
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18
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Kesir M, Deth RC, Malioutov M. Quantitative Simulation of Redox/Methylation Metabolism in Neuronal Cells. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.859.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mustafa Kesir
- Department of MathematicsNortheastern UniversityBostonMA
| | - Richard C Deth
- Department of Pharmaceutical SciencesNortheastern UniversityBostonMA
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19
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Al-Farsi YM, Waly MI, Deth RC, Al-Sharbati MM, Al-Shafaee M, Al-Farsi O, Al-Khaduri MM, Gupta I, Ali A, Al-Khalili M, Al-Adawi S, Hodgson NW, Ouhtit A. Low folate and vitamin B12 nourishment is common in Omani children with newly diagnosed autism. Nutrition 2013; 29:537-41. [DOI: 10.1016/j.nut.2012.09.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 09/03/2012] [Accepted: 09/05/2012] [Indexed: 10/27/2022]
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Muratore CR, Hodgson NW, Trivedi MS, Abdolmaleky HM, Persico AM, Lintas C, De La Monte S, Deth RC. Age-dependent decrease and alternative splicing of methionine synthase mRNA in human cerebral cortex and an accelerated decrease in autism. PLoS One 2013; 8:e56927. [PMID: 23437274 PMCID: PMC3577685 DOI: 10.1371/journal.pone.0056927] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 01/16/2013] [Indexed: 12/22/2022] Open
Abstract
The folate and vitamin B12-dependent enzyme methionine synthase (MS) is highly sensitive to cellular oxidative status, and lower MS activity increases production of the antioxidant glutathione, while simultaneously decreasing more than 200 methylation reactions, broadly affecting metabolic activity. MS mRNA levels in postmortem human cortex from subjects across the lifespan were measured and a dramatic progressive biphasic decrease of more than 400-fold from 28 weeks of gestation to 84 years was observed. Further analysis revealed alternative splicing of MS mRNA, including deletion of folate-binding domain exons and age-dependent deletion of exons from the cap domain, which protects vitamin B12 (cobalamin) from oxidation. Although three species of MS were evident at the protein level, corresponding to full-length and alternatively spliced mRNA transcripts, decreasing mRNA levels across the lifespan were not associated with significant changes in MS protein or methionine levels. MS mRNA levels were significantly lower in autistic subjects, especially at younger ages, and this decrease was replicated in cultured human neuronal cells by treatment with TNF-α, whose CSF levels are elevated in autism. These novel findings suggest that rather than serving as a housekeeping enzyme, MS has a broad and dynamic role in coordinating metabolism in the brain during development and aging. Factors adversely affecting MS activity, such as oxidative stress, can be a source of risk for neurological disorders across the lifespan via their impact on methylation reactions, including epigenetic regulation of gene expression.
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Affiliation(s)
- Christina R. Muratore
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, Massachusetts, United States of America
| | - Nathaniel W. Hodgson
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, Massachusetts, United States of America
| | - Malav S. Trivedi
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, Massachusetts, United States of America
| | - Hamid M. Abdolmaleky
- Genetics Program, School of Medicine, Boston University, Boston, Massachusetts, United States of America
| | - Antonio M. Persico
- Laboratory of Molecular Psychiatry and Neurogenetics, University Campus Bio-Medico, Rome, Italy
| | - Carla Lintas
- Laboratory of Molecular Psychiatry and Neurogenetics, University Campus Bio-Medico, Rome, Italy
| | - Suzanne De La Monte
- Department of Medicine and Pathology, Rhode Island Hospital and Warren Alpert School of Medicine at Brown University, Providence, Rhode Island, United States of America
| | - Richard C. Deth
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, Boston, Massachusetts, United States of America
- * E-mail:
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21
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Al-Farsi YM, Waly MI, Al-Sharbati MM, Al-Shafaee MA, Al-Farsi OA, Al-Khaduri MM, Gupta I, Ouhtit A, Al-Adawi S, Al-Said MF, Deth RC. Levels of heavy metals and essential minerals in hair samples of children with autism in Oman: a case-control study. Biol Trace Elem Res 2013. [PMID: 23188679 DOI: 10.1007/s12011-012-9553-z] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Toxic levels of heavy metals and low levels of essential minerals have been suggested to play a critical role in the pathogenesis of autism spectrum disorders (ASD). This study documents the levels of heavy metals and essential minerals in hair samples of children with ASD in Muscat, the urbanized capital of Oman, Muscat. The study included 27 children with ASD and 27 matched non-ASD controls. Parental interviews were held and dietary intake questionnaires completed in conjunction with the collection of hair samples. Analysis of heavy metals and essential minerals was carried out by inductively coupled plasma mass spectrometry. Chi-square analysis and non-parametric Fisher's exact tests were used to assess statistical significance. Children with ASD had significantly higher levels of all 11 analyzed heavy metals in their hair samples (P < 0.05), ranging from 150 to 365 % of control levels. ASD children also had significantly higher levels of essential minerals sulfur, sodium, magnesium, potassium, zinc, and iron, but lower levels of calcium and copper in their hair samples. This study corroborates data from previous studies in different parts of the world indicating the presence of elevated levels of heavy metals and selective depletion of essential minerals in the hair of children with ASD.
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Affiliation(s)
- Yahya M Al-Farsi
- Department of Family Medicine and Public Health, College of Medicine and Health Sciences, Sultan Qaboos University, Al-Khoudh, Oman.
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22
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Terhune TD, Deth RC. How aluminum adjuvants could promote and enhance non-target IgE synthesis in a genetically-vulnerable sub-population. J Immunotoxicol 2012; 10:210-22. [PMID: 22967010 DOI: 10.3109/1547691x.2012.708366] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Aluminum-containing adjuvants increase the effectiveness of vaccination, but their ability to augment immune responsiveness also carries the risk of eliciting non-target responses, especially in genetically susceptible individuals. This study reviews the relevant actions of aluminum adjuvants and sources of genetic risk that can combine to adversely affect a vulnerable sub-population. Aluminum adjuvants promote oxidative stress and increase inflammasome activity, leading to the release of IL-1β, IL-18, and IL-33, but not the important regulatory cytokine IL-12. In addition, they stimulate macrophages to produce PGE₂, which also has a role in regulating immune responses. This aluminum-induced cytokine context leads to a T(H)2 immune response, characterized by the further release of IL-3, IL-4, IL-5, IL-9, IL-13, and IgE-potentiating factors such as sCD23. Genetic variants in cytokine genes, such as IL-4, IL-13, IL-33, and IL-18 influence the response to vaccines in children and are also associated with atopy. These genetic factors may therefore define a genetically-vulnerable sub-population, children with a family history of atopy, who may experience an exaggerated T(H)2 immune response to aluminum-containing vaccines. IL-4, sCD23, and IgE are common factors for both atopy and the immune-stimulating properties of aluminum adjuvants. IL-4 is critical in the production of IgE and total IgE up-regulation. IL-4 has also been reported to induce the production of sCD23 and trigger resting sIgM+, sIgD+ B-cells to switch to sIgE+ B-cells, making them targets for IgE-potentiating factors. Further, the actions of IgE-potentiating factors on sIgE+ B-cells are polyclonal and unrestricted, triggering their differentiation into IgE-forming plasma cells. These actions provide a mechanism for aluminum-adjuvant promotion and enhancement of non-target IgE in a genetically vulnerable sub-population. Identification of these individuals may decrease the risk of adverse events associated with the use of aluminum-containing vaccines.
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Affiliation(s)
- Todd D Terhune
- Department of Pharmaceutical Sciences, Northeastern University, 148 TF, 360 Huntington Avenue, Boston, MA 02115, USA.
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23
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Al-Farsi YM, Al-Sharbati MM, Waly MI, Al-Farsi OA, Al-Shafaee MA, Al-Khaduri MM, Trivedi MS, Deth RC. Effect of suboptimal breast-feeding on occurrence of autism: A case–control study. Nutrition 2012; 28:e27-32. [DOI: 10.1016/j.nut.2012.01.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 11/21/2011] [Accepted: 01/16/2012] [Indexed: 10/28/2022]
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Trivedi MS, Deth RC. Role of a redox-based methylation switch in mRNA life cycle (pre- and post-transcriptional maturation) and protein turnover: implications in neurological disorders. Front Neurosci 2012; 6:92. [PMID: 22740813 PMCID: PMC3382963 DOI: 10.3389/fnins.2012.00092] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 06/06/2012] [Indexed: 12/31/2022] Open
Abstract
Homeostatic synaptic scaling in response to neuronal stimulus or activation, and due to changes in cellular niche, is an important phenomenon for memory consolidation, retrieval, and other similar cognitive functions (Turrigiano and Nelson, 2004). Neurological disorders and cognitive disabilities in autism, Rett syndrome, schizophrenia, dementia, etc., are strongly correlated to alterations in protein expression (both synaptic and cytoplasmic; Cajigas et al., 2010). This correlation suggests that efficient temporal regulation of synaptic protein expression is important for synaptic plasticity. In addition, equilibrium between mRNA processing, protein translation, and protein turnover is a critical sensor/trigger for recording synaptic information, normal cognition, and behavior (Cajigas et al., 2010). Thus a regulatory switch, which controls the lifespan, maturation, and processing of mRNA, might influence cognition and adaptive behavior. Here, we propose a two part novel hypothesis that methylation might act as this suggested coordinating switch to critically regulate mRNA maturation at (1) the pre-transcription level, by regulating precursor-RNA processing into mRNA, via other non-coding RNAs and their influence on splicing phenomenon, and (2) the post-transcription level by modulating the regulatory functions of ribonucleoproteins and RNA binding proteins in mRNA translation, dendritic translocation as well as protein synthesis and synaptic turnover. DNA methylation changes are well recognized and highly correlated to gene expression levels as well as, learning and memory; however, RNA methylation changes are recently characterized and yet their functional implications are not established. This review article provides some insight on the intriguing consequences of changes in methylation levels on mRNA life-cycle. We also suggest that, since methylation is under the control of glutathione anti-oxidant levels (Lertratanangkoon et al., 1997), the redox status of neurons might be the central regulatory switch for methylation-based changes in mRNA processing, protein expression, and turnover. Lastly, we also describe experimental methods and techniques which might help researchers to evaluate the suggested hypothesis.
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Affiliation(s)
- Malav S Trivedi
- Department of Pharmaceutical Sciences, Northeastern University Boston, MA, USA
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25
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26
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Al-Farsi YM, Al-Khaduri MM, Al-Sharbati MM, Waly MI, Al-Farsi OA, Al-Shafaee MA, Deth RC. Association of adverse antenatal and perinatal events with occurrence of Autism: A Case Control Study. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1006.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yahya M Al-Farsi
- Family Medicine and Public Health DepartmentCollege of Medicine and Health SciencesSultan Qaboos UniversityMuscatOman
| | - Maha M Al-Khaduri
- Obstetrics and Gynecology DepartmentCollege of Medicine and Health SciencesSultan Qaboos UniversityMuscatOman
| | - Marwan M Al-Sharbati
- Behavioral Medicine DepartmentCollege of Medicine and Health SciencesSultan Qaboos UniversityMuscatOman
| | - Mostafa I Waly
- Food Science and Nutrition DepartmentCollege of Medicine and Health SciencesSultan Qaboos UniversityMuscatOman
| | - Omar A Al-Farsi
- Family Medicine and Public Health DepartmentCollege of Medicine and Health SciencesSultan Qaboos UniversityMuscatOman
| | - Mohammed A Al-Shafaee
- Family Medicine and Public Health DepartmentCollege of Medicine and Health SciencesSultan Qaboos UniversityMuscatOman
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27
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Ali A, Waly MI, Al-Farsi YM, Essa MM, Al-Sharbati MM, Deth RC. Hyperhomocysteinemia among Omani autistic children: a case-control study. Acta Biochim Pol 2011; 58:547-551. [PMID: 22187679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 11/25/2011] [Accepted: 12/11/2011] [Indexed: 05/31/2023]
Abstract
High serum homocysteine (Hcy) level is regarded as an indicator for impairment of folate-dependent methionine cycle and is associated with oxidative stress. In a case control study, we evaluated eighty 3-5 years old Omani children (40 diagnosed with Autism Spectrum Disorder and 40 their age and gender matched controls) for their fasting serum homocysteine levels as a biomarker of Autism Spectrum Disorder (ASD). Serum folate and vitamin B(12) status were also evaluated. The serum homocysteine was measured using an enzyme immunoassay (EIA) technique whereas folate and vitamin B(12) were measured using an automated random access immune-assay system. The results indicated that mean serum Hcy levels were significantly (P < 0.05) higher in autistic children (20.1 ± 3.3 µmol/L) as compared to controls (9.64 ± 2.1 µmol/L). Significantly (P < 0.05) lower serum folate (1.8 ± 0.4 µg/L) and vitamin B(12) (191.1 ± 0.9 pg/mL) levels were observed in autistic children as compared to controls (6.1 ± 0.6 µg/L and 288.9 ± 1.3 pg/mL, respectively). The levels of homocysteine in autistic children were also much higher as compared to normal reference values (5-15 µmol/L). The results suggest that high fasting serum homocysteine and low folate and vitamin B(12) levels could be used as clinical biomarkers for an early diagnosis and management of ASD.
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Affiliation(s)
- Amanat Ali
- Department of Food Science and Nutrition, College of Agricultural and Marine Sciences, Sultan Qaboos University, Oman.
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28
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Ali A, Waly MI, Al-Farsi YM, Essa MM, Al-Sharbati MM, Deth RC. Hyperhomocysteinemia among Omani autistic children: a case-control study. Acta Biochim Pol 2011. [DOI: 10.18388/abp.2011_2223] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
High serum homocysteine (Hcy) level is regarded as an indicator for impairment of folate-dependent methionine cycle and is associated with oxidative stress. In a case control study, we evaluated eighty 3-5 years old Omani children (40 diagnosed with Autism Spectrum Disorder and 40 their age and gender matched controls) for their fasting serum homocysteine levels as a biomarker of Autism Spectrum Disorder (ASD). Serum folate and vitamin B(12) status were also evaluated. The serum homocysteine was measured using an enzyme immunoassay (EIA) technique whereas folate and vitamin B(12) were measured using an automated random access immune-assay system. The results indicated that mean serum Hcy levels were significantly (P < 0.05) higher in autistic children (20.1 ± 3.3 µmol/L) as compared to controls (9.64 ± 2.1 µmol/L). Significantly (P < 0.05) lower serum folate (1.8 ± 0.4 µg/L) and vitamin B(12) (191.1 ± 0.9 pg/mL) levels were observed in autistic children as compared to controls (6.1 ± 0.6 µg/L and 288.9 ± 1.3 pg/mL, respectively). The levels of homocysteine in autistic children were also much higher as compared to normal reference values (5-15 µmol/L). The results suggest that high fasting serum homocysteine and low folate and vitamin B(12) levels could be used as clinical biomarkers for an early diagnosis and management of ASD.
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Waly MI, Kharbanda KK, Deth RC. Ethanol lowers glutathione in rat liver and brain and inhibits methionine synthase in a cobalamin-dependent manner. Alcohol Clin Exp Res 2010; 35:277-83. [PMID: 21121936 DOI: 10.1111/j.1530-0277.2010.01343.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Methionine synthase (MS) is a ubiquitous enzyme that requires vitamin B12 (cobalamin) and 5-methyl-tetrahydrofolate for the methylation of homocysteine to methionine. Previous studies have shown that acute or chronic ethanol (ETOH) administration results in the inhibition of MS and depletion of glutathione (GSH), and it has been proposed that GSH is required for the synthesis of methylcobalamin (MeCbl). METHODS We measured GSH levels and investigated the ability of different cobalamin cofactors [cyano- (CNCbl), glutathionyl- (GSCbl), hydroxo- (OHCbl), and MeCbl] to support MS activity in liver and brain cortex from control and ETOH-treated rats. RESULTS In control animals, MS activity was higher in liver than in cortex for all cobalamins and MeCbl-based activity was higher than for other cofactors. S-adenosylmethionine (SAM) was required for OHCbl, CNCbl, and GSCbl-based activity, but not for MeCbl. Feeding an ETOH-containing diet for four weeks caused a significant decrease in liver MS activity, in a cobalamin-dependent manner (OHCbl ≥ CNCbl > GSCbl > MeCbl). In brain cortex, OHCbl, CNCbl, and GSCbl-based activity was reduced by ETOH treatment, but MeCbl-based activity was unaffected. GSH levels were reduced by ETOH treatment in both liver and cortex homogenates, and addition of GSH restored OHCbl-based MS activity to control levels. Betaine administration had no significant effect on GSH levels or MS activity in either control or ETOH-fed groups. CONCLUSIONS The ETOH-induced decrease in OHCbl-based MS activity is secondary to decreased GSH levels and a decreased ability to synthesize MeCbl. The ability of MeCbl to completely offset ETOH inhibition in brain cortex, but not liver, suggests tissue-specific differences in the GSH-dependent regulation of MS activity.
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Affiliation(s)
- Mostafa I Waly
- Department of Food Science and Nutrition, Sultan Qaboos University, Muscat, Sultanate of Oman
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30
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Kuznetsova AY, Deth RC. A model for modulation of neuronal synchronization by D4 dopamine receptor-mediated phospholipid methylation. J Comput Neurosci 2007; 24:314-29. [PMID: 17929154 DOI: 10.1007/s10827-007-0057-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Revised: 08/29/2007] [Accepted: 09/24/2007] [Indexed: 12/16/2022]
Abstract
We describe a new molecular mechanism of dopamine-induced membrane protein modulation that can tune neuronal oscillation frequency to attention-related gamma rhythm. This mechanism is based on the unique ability of D4 dopamine receptors (D4R) to carry out phospholipid methylation (PLM) that may affect the kinetics of ion channels. We show that by deceasing the inertia of the delayed rectifier potassium channel, a transition to 40 Hz oscillations can be achieved. Decreased potassium channel inertia shortens spike duration and decreases the interspike interval via its influence on the calcium-dependent potassium current. This mechanism leads to a transition to attention-related gamma oscillations in a pyramidal cell-interneuron network. The higher frequency and better synchronization is observed with PLM affecting pyramidal neurons only, and recurrent excitation between pyramidal neurons is important for synchronization. Thus dopamine-stimulated methylation of membrane phospholipids may be an important mechanism for modulating firing activity, while impaired methylation can contribute to disorders of attention.
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Affiliation(s)
- Anna Y Kuznetsova
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier St., Suite D, New Orleans, LA 70112, USA
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31
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Culley DJ, Raghavan SV, Waly M, Baxter MG, Yukhananov R, Deth RC, Crosby G. Nitrous oxide decreases cortical methionine synthase transiently but produces lasting memory impairment in aged rats. Anesth Analg 2007; 105:83-8. [PMID: 17578961 DOI: 10.1213/01.ane.0000266491.53318.20] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Nitrous oxide is a commonly used anesthetic that inhibits the activity of methionine synthase, an enzyme involved in methylation reactions and DNA synthesis and repair. This inhibition triggers vacuole formation and degeneration of neurons in areas of the developing and mature brain that are important for spatial memory, raising the possibility that nitrous oxide might have sustained effects on learning. METHODS To test this possibility, we randomized 18-month-old Fischer 344 rats (n = 13 per group) to 4 h of 70% nitrous oxide + 30% oxygen or 70% nitrogen + 30% oxygen (control) and assessed memory using a 12-arm radial maze for 14 days beginning 2 days after nitrous oxide inhalation. In separate, identically treated groups of rats, we measured methionine synthase activity in the cortex and liver at the end of nitrous oxide exposure and 2 days later (n = 3 rats per group per time point) using a standard assay. RESULTS Liver and cortical methionine synthase was inhibited during nitrous oxide inhalation (6% and 23% of control in liver and cortex, respectively; P < 0.01). Liver enzyme activity remained depressed 2 days later, whereas cortical enzyme activity recovered. There was no difference in error rate between control and nitrous oxide treated rats. However, those exposed to nitrous oxide took more time to complete the maze and made fewer correct choices before first error (P < 0.05). CONCLUSIONS Sedation with 70% nitrous oxide profoundly, but transiently, reduces the activity of cortical methionine synthase but produces lasting impairment in spatial working memory in aged rats.
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Affiliation(s)
- Deborah J Culley
- Department of Anesthesiology Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115, USA
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32
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Waly MI, Deth RC, Kharbanda KK. Ethanol Inhibition of Methionine Synthase in Rat Liver and Cortex: Role of GSH Depletion and Different Cobalamin Cofactors. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a344-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Richard C. Deth
- Pharmaceutical sciences Dept.NORTHEASTERN UNIVERSITY312 Mugar Bldg., 360 Huntington AvenueBostonMA02115
| | - Kusum K. Kharbanda
- Department of Veterans Affairs Medical CenterVA Alcohol Research CenterDepartment of Veterans Affairs Medical CenterOmahaNE68105
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33
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Deth RC. D4 Dopamine Receptors and the Molecular Mechanism of Attention. CNS Drug Reviews 2006. [DOI: 10.1111/j.1527-3458.2000.tb00163.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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34
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Zhu Q, Qi LJ, Shi A, Abou-Samra A, Deth RC. Protein kinase C regulates alpha(2A/D)-adrenoceptor constitutive activity. Pharmacology 2005; 71:80-90. [PMID: 15118347 DOI: 10.1159/000076944] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Accepted: 10/14/2003] [Indexed: 11/19/2022]
Abstract
We investigated a possible role for protein kinases in the constitutive activity of alpha(2A/D) adrenoceptors in membranes from transfected PC12 cells, using a [35S]GTPgammaS binding assay. After treatment of intact cells with various protein kinase inhibitors, constitutive activity was assessed by the reduction in basal GTP binding caused by the inverse agonist rauwolscine (RAU). Inhibitors of protein kinase C (PKC) caused the loss of RAU-sensitive GTP binding, while inhibitors of other protein kinases were ineffective. Anti-G(alpha) antibody treatments showed that constitutive alpha(2A/D)-receptor activity is directed toward different G proteins than agonist-stimulated activity. T373A mutant receptors exhibited increased constitutive activity, including a component that was insensitive to PKC inhibition. Since T373 is located within a putative G(i/o) activator sequence, these results suggest that PKC-dependent phosphorylation of T373 increases alpha(2A/D)-adrenergic receptor constitutive activity and causes a switch in G protein preference.
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MESH Headings
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Antibodies/pharmacology
- Constitutive Androstane Receptor
- Epinephrine/pharmacology
- GTP-Binding Proteins/antagonists & inhibitors
- GTP-Binding Proteins/chemistry
- GTP-Binding Proteins/metabolism
- Humans
- Mutation, Missense
- PC12 Cells
- Protein Conformation
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/genetics
- Protein Kinase C/metabolism
- Rats
- Receptors, Adrenergic, alpha-2/chemistry
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/metabolism
- Sequence Analysis, Protein/methods
- Sulfur Radioisotopes/metabolism
- Threonine/chemistry
- Threonine/drug effects
- Threonine/metabolism
- Transcription Factors/chemistry
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transfection/methods
- Yohimbine/antagonists & inhibitors
- Yohimbine/metabolism
- Yohimbine/pharmacology
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Affiliation(s)
- Qingbing Zhu
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
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35
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Waly M, Olteanu H, Banerjee R, Choi SW, Mason JB, Parker BS, Sukumar S, Shim S, Sharma A, Benzecry JM, Power-Charnitsky VA, Deth RC. Activation of methionine synthase by insulin-like growth factor-1 and dopamine: a target for neurodevelopmental toxins and thimerosal. Mol Psychiatry 2004; 9:358-70. [PMID: 14745455 DOI: 10.1038/sj.mp.4001476] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Methylation events play a critical role in the ability of growth factors to promote normal development. Neurodevelopmental toxins, such as ethanol and heavy metals, interrupt growth factor signaling, raising the possibility that they might exert adverse effects on methylation. We found that insulin-like growth factor-1 (IGF-1)- and dopamine-stimulated methionine synthase (MS) activity and folate-dependent methylation of phospholipids in SH-SY5Y human neuroblastoma cells, via a PI3-kinase- and MAP-kinase-dependent mechanism. The stimulation of this pathway increased DNA methylation, while its inhibition increased methylation-sensitive gene expression. Ethanol potently interfered with IGF-1 activation of MS and blocked its effect on DNA methylation, whereas it did not inhibit the effects of dopamine. Metal ions potently affected IGF-1 and dopamine-stimulated MS activity, as well as folate-dependent phospholipid methylation: Cu(2+) promoted enzyme activity and methylation, while Cu(+), Pb(2+), Hg(2+) and Al(3+) were inhibitory. The ethylmercury-containing preservative thimerosal inhibited both IGF-1- and dopamine-stimulated methylation with an IC(50) of 1 nM and eliminated MS activity. Our findings outline a novel growth factor signaling pathway that regulates MS activity and thereby modulates methylation reactions, including DNA methylation. The potent inhibition of this pathway by ethanol, lead, mercury, aluminum and thimerosal suggests that it may be an important target of neurodevelopmental toxins.
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Affiliation(s)
- M Waly
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
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36
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Abstract
Dopamine D4 receptors (D4 receptors) mediate dopamine-stimulated, folate-dependent phospholipid methylation. To investigate possible regulation of this multi-step D4 receptor-mediated phospholipid methylation cycle by protein kinases, specific kinase activators and inhibitors were studied in SK-N-MC human neuroblastoma cells, using [14C] formate to label folate-derived single-carbon groups. Phorbol dibutyrate (PDB), an activator of protein kinase C, stimulated basal phospholipid methylation and also shifted the dose-response curve for dopamine-stimulated phospholipid methylation to the right by more than an order of magnitude. Calphostin C, an inhibitor of protein kinase C, had little effect on basal phospholipid methylation but significantly inhibited dopamine-stimulated phospholipid methylation and also blocked the stimulatory response to PDB. Chelerythrine, which inhibits protein kinase C and other kinases, strongly inhibited both basal and dopamine-stimulated phospholipid methylation. Forskolin, an activator of protein kinase A, inhibited basal and dopamine-stimulated phospholipid methylation, but only at high concentrations while Rp-cAMP, an inhibitor of protein kinase A, did not block this effect. Inhibition of protein kinase G produced a modest decrease in dopamine-stimulated phospholipid methylation, but neither sodium nitroprusside, which increases nitric oxide (NO) production and activates protein kinase G, nor the NO synthase inhibitor N-nitro-L-arginine had any effect on basal or dopamine-stimulated phospholipid methylation. These observations indicate that protein kinase C is an important regulator of basal and D4 receptor-mediated folate-dependent phospholipid methylation, whereas protein kinase A and protein kinase G have a lesser or minimal role.
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Affiliation(s)
- A Sharma
- Department of Pharmaceutical Sciences, 312 Mugar Life Sciences Building, 360 Huntington Avenue, Northeastern University, Boston, MA 02115, USA
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37
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Zhao R, Chen Y, Tan W, Waly M, Sharma A, Stover P, Rosowsky A, Malewicz B, Deth RC. Relationship between dopamine-stimulated phospholipid methylation and the single-carbon folate pathway. J Neurochem 2001; 78:788-96. [PMID: 11520899 DOI: 10.1046/j.1471-4159.2001.00471.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In a previous study we demonstrated the ability of dopamine (DA) to stimulate phospholipid methylation (PLM) via a novel mechanism involving the D4 dopamine receptor (D4R) in which single-carbon folates appeared to be the primary source of methyl groups. To further understand the relationship between D4R-mediated PLM and folate metabolism, we examined the effect of several folate pathway interventions on the level of basal and DA-stimulated incorporation of [14C]-labeled formate into phospholipids in cultured SH-SY5Y neuroblastoma cells. These interventions included: (i) Overexpression of methenyltetrahydrofolate synthetase (MTHFS). (ii) Treatment with 5-formylTHF. (iii) Treatment with the MTHFS inhibitor 5-formyltetrahydrohomofolic acid (5-formylTHHF). (iv) Growth in nucleoside-free media. 31P-NMR was also used to follow DA-induced changes in cell phospholipid composition. MTHFS overexpression and 5-formylTHHF treatment, both of which lower 5-methylTHF levels, each reduced basal PLM and its stimulation by DA. In contrast, 5-formylTHF, which increases 5-methylTHF, caused a dose-dependent increase in both basal and DA-stimulated PLM. Growth in nucleoside-free media caused time-dependent changes in PLM, which were due to the absence of purine nucleosides. While basal PLM was maintained at a reduced level, DA-stimulated PLM was initially increased followed by a later decrease. Together, these findings indicate a close functional relationship between single-carbon folate metabolism and DA-stimulated PLM, consistent with a role for 5-methylTHF as the methyl donor for the D4R-mediated process.
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Affiliation(s)
- R Zhao
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts 02115, USA
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38
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Tian WN, Deth RC. Differences in efficacy and Na(+) sensitivity between alpha(2B) and alpha(2D) adrenergic receptors: implications for R and R* states. Pharmacology 2000; 61:14-21. [PMID: 10895076 DOI: 10.1159/000028375] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The ability of Na(+) ions to modulate coupling of alpha(2B)- and alpha(2D)-adrenergic receptors to G proteins was investigated in isolated membranes from transfected PC12 and NIH 3T3 fibroblast cells. The initial rate of epinephrine-stimulated [(35)S]GTPgammaS binding was higher for alpha(2D)-receptors (the rat homolog of the alpha(2A)-receptor) in both cell types, whereas both alpha(2B)- and alpha(2D)-receptor responses were higher in PC12 cell membranes. Pertussis toxin completely blocked agonist-stimulated binding. Graded increases in Na(+) caused a progressive loss of basal GTP binding, indicative of its ability to reduce the level of the active R* state of the receptor. This inhibitory effect of Na(+) was more pronounced in PC12/alpha(2B) than PC12/alpha(2D) membranes. Epinephrine-stimulated GTP binding in PC12/alpha(2B) membranes was also more sensitive to Na(+) inhibition than in PC12/alpha(2D) membranes. In saturation [(35)S]GTPgammaS binding studies, the presence of Na(+) reduced apparent GTP affinity, and its effect was greater in PC12/ alpha(2B) membranes, consistent with a greater reduction in the active R* conformation of the receptor. The higher efficacy of epinephrine at alpha(2D) receptors and their lesser sensitivity to Na(+) are both indicative of a more stable R* state. Together these results suggest that differences in the modulatory influence of Na(+) within a family of G(i)-coupled receptors may reflect differences in the stability of the active R* state.
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Affiliation(s)
- W N Tian
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
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39
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Tian WN, Miller DD, Deth RC. Bidirectional allosteric effects of agonists and GTP at alpha(2A/D)-adrenoceptors. J Pharmacol Exp Ther 2000; 292:664-71. [PMID: 10640304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Agonists and GTP exert reciprocal effects on the stability of the G protein-coupled receptor/G protein complex, implying bidirectional control over the receptor/G protein interface. To investigate this relationship, we compared the ability of a series of hydroxyl-substituted phenethylamine and imidazoline agonists to stimulate [(35)S]guanosine 5'-O-(3-thio)triphosphate ([(35)S]GTPgammaS) binding in membranes from alpha(2A/D)-adrenergic receptor-transfected PC12 cells with the magnitude of the GTP-induced reduction in agonist affinity in [(3)H]rauwolscine-binding studies. Agents previously described as full and partial agonists in functional studies showed similar relative efficacies in promoting GTP binding (r = 0.97) as well as similar relative potencies (r = 0.94). Efficacy among agonists for promotion of [(35)S]GTPgammaS binding was closely correlated with the relative influence of GTPgammaS on agonist binding (r = 0.97), consistent with a bidirectional allosteric influence by agonists and GTP on receptor/G protein complexation. In an additional series of tolazoline derivatives, a range in efficacy from full agonism to strong inverse agonism was observed, depending on the presence or absence of hydroxyl substituents. Together these results suggest that agonist-induced repositioning of transmembrane helices via their hydroxyl interactions is a critical determinant of the stability of the receptor/G protein complex and therefore of agonist efficacy.
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Affiliation(s)
- W N Tian
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts, USA
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40
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Abstract
To clarify the role of protein kinase C (PKC) in regulating the coupling pathway of alpha(2)-adrenergic receptors, we examined receptor activation of phospholipase D (PLD) in PC12 cells overexpressing alpha(2A/D) receptors, using [(3)H]phosphatidylbutanol formation as an index of PLD activity. In intact PC12/alpha(2A/D) cells, the ability of either epinephrine or the alpha(2)-receptor-selective agonist UK14304 to stimulate PLD was completely dependent on concomitant PKC activation. Pretreatment with the PKC activator phorbol dibutyrate revealed an agonist-stimulated PLD activity which was blocked by the alpha(2)-receptor-selective antagonist rauwolscine and by pertussis toxin treatment. Removal of extracellular calcium or tyrosine kinase inhibition by genistein pretreatment also eliminated the ability of epinephrine to stimulate PLD. These results indicate that alpha(2A/D)-adrenergic receptors couple via pertussis toxin-sensitive G proteins to PLD in a PKC-requiring and tyrosine kinase regulated manner.
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Affiliation(s)
- A Jinsi-Parimoo
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
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41
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Sharma A, Kramer ML, Wick PF, Liu D, Chari S, Shim S, Tan W, Ouellette D, Nagata M, DuRand CJ, Kotb M, Deth RC. D4 dopamine receptor-mediated phospholipid methylation and its implications for mental illnesses such as schizophrenia. Mol Psychiatry 1999; 4:235-46. [PMID: 10395213 DOI: 10.1038/sj.mp.4000522] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previous studies have shown D2-like dopamine receptor involvement in the regulation of phospholipid methylation (PLM), while others have documented impaired methionine and folate metabolism in schizophrenia. Utilizing [14C]formate labeling in cultured neuroblastoma cell lines, we now show that D4 dopamine receptors (D4R) mediate the stimulatory effect of dopamine (DA) on PLM. The effect of DA was potently blocked by highly D4R-selective antagonists and stimulated by the D4R-selective agonist CP-226269. DA-stimulated PLM was dependent upon the activity of methionine cycle enzymes, but DA failed to increase PLM in [3H]methionine labeling studies, indicating that a methionine residue in the D4R might be involved in mediating PLM. A direct role for MET313, located on transmembrane helix No. 6 immediately adjacent to phospholipid headgroups, was further suggested from adenosylation, site-directed mutagenesis and GTP-binding results. A comparison of PLM in lymphocytes from schizophrenia patients vs control samples showed a four-fold lower activity in the schizophrenia group. These findings reveal a novel mechanism by which the D4R can regulate membrane composition. Abnormalities in D4R-mediated PLM may be important in psychiatric illnesses such as schizophrenia.
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Affiliation(s)
- A Sharma
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts 02115, USA
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42
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Abstract
We have previously shown that alpha2-adrenergic receptor-mediated coupling to phospholipase D (PLD) in vascular tissues requires a tyrosine kinase activity (Jinsi, A., Paradise, J., and Deth, R. C. (1996) Eur. J. Pharmacol. 302, 183-190). To further clarify this mode of regulation we reconstituted alpha2A/D-adrenergic receptor-stimulated PLD activity in PC12 cells expressing the cloned receptor. [3H]Myristic acid-labeled cells were lysed by nitrogen cavitation, and aliquots of subnuclear fraction were utilized in the PLD assay. Agonist-stimulated PLD activity was measured in the presence of 0.4% butanol as [3H]phosphatidylbutanol formation. Both GTP and its non-hydrolyzable analog guanosine 5'-O-(thiotriphosphate) stimulated PLD activity in a concentration- and time-dependent manner that required co-activation of protein kinase C by phorbol dibutyrate. Addition of epinephrine produced a 3-fold stimulation of PLD activity in the presence of GTP and GDP. This agonist-stimulated PLD activity was completely blocked by the alpha2-adrenergic receptor antagonist rauwolscine and by Clostridium botulinum toxin as well as by antibodies directed against either pp60(src), RhoA, or Ras GTPase-activating protein. These results indicate that coupling of the alpha2A/D-adrenergic receptor to PLD is complexly regulated by both the tyrosine kinase pp60(src) and the low molecular weight G protein RhoA.
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Affiliation(s)
- A Jinsi-Parimoo
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts 02115, USA
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43
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Abstract
Based on the presence of multiple proline-rich motifs in the huntingtin sequence, we tested its possible association with epidermal growth factor (EGF) receptor signaling complexes through SH3 domain-containing modules. We found that huntingtin is associated with Grb2, RasGAP, and tyrosine-phosphorylated EGF receptor. These associations are regulated by activation of the EGF receptor, suggesting that they may be part of EGF receptor-mediated cellular signaling cascade. In vitro binding studies indicate that SH3 domains of Grb2 or RasGAP are required for their binding to huntingtin. Our results suggest that huntingtin may be a unique adapter protein for EGF receptor-mediated signaling and may be involved in the regulation of Ras-dependent signaling pathways.
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Affiliation(s)
- Y F Liu
- Center for Neurological Disease, Brigham and Women's Hospital and Department of Neurology, Harvard Medical School, Boston, Massachusetts 02114, USA
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44
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Abstract
Since previous studies had indicated a role for tyrosine kinases in alpha 2-adrenoceptor-induced contractile responses in other blood vessels, as well as in the activation of phospholipase D, we examined the sensitivity of these responses in rat aorta to the tyrosine kinase inhibitor genistein. Contractions induced by both noradrenaline and the alpha 2-adrenoceptor-selective agonist UK14304 (5-bromo-6-[2-imidazolin-2-yl-amino]-quinoxaline) were fully inhibited by genistein, with the latter responses being more sensitive. Contractions induced by high K+ buffer were also inhibited, but to a lesser extent. Both agonists caused a stimulation of phospholipase D activity, which could be blocked by pretreatment with pertussis toxin, indicating involvement of either Gi or Go. Genistein completely inhibited the agonist-induced phospholipase D activity and also substantially reduced the basal level of phospholipase D activity. Pretreatment with either the alpha 1-adrenoceptor antagonist prazosin or the alpha 2-adrenoceptor antagonist rauwolscine was also effective in eliminating the agonist-induced increase of phospholipase D. These results indicate that a tyrosine kinase-regulated phospholipase D plays a critical role in alpha-adrenoceptor-induced contractions of the rat aorta and that stimulation of both alpha 1- and alpha 2-adrenoceptors is essential to allow phospholipase activation.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/antagonists & inhibitors
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Adrenergic alpha-Agonists/pharmacology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- Brimonidine Tartrate
- Calcium Channel Agonists/pharmacology
- Dose-Response Relationship, Drug
- Enzyme Activation/drug effects
- Genistein
- Isoflavones/pharmacology
- Male
- Muscle Contraction/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Norepinephrine/antagonists & inhibitors
- Norepinephrine/pharmacology
- Pertussis Toxin
- Phospholipase D/metabolism
- Potassium/pharmacology
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/metabolism
- Protein-Tyrosine Kinases/pharmacology
- Quinoxalines/antagonists & inhibitors
- Rats
- Receptors, Adrenergic, alpha/drug effects
- Receptors, Adrenergic, alpha/metabolism
- Virulence Factors, Bordetella/pharmacology
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Affiliation(s)
- A Jinsi
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
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45
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Tian WN, Duzic E, Deth RC. Evaluation of agonist efficacy and receptor reserve for alpha 2D-adrenergic receptor regulated G protein activation in PC12 cell membranes. Pharmacology 1996; 52:252-62. [PMID: 8841088 DOI: 10.1159/000139390] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The receptor-coupling efficiency for epinephrine (EPI) stimulated heterotrimeric G protein activation was studied at the G protein level in membranes prepared from PC12 cells expressing cloned alpha 2D-adrenergic receptors (alpha 2D-AR). After pretreatment with different concentrations of N-ethoxycarbonyl-1,2-dihydroquinoline, which irreversibly inactivates alpha 2D-AR, the portion of alpha 2D-ARs remaining active (q) was estimated from EPI-stimulated [35S]GTP gamma S binding. This function-derived estimate was close to the actual remaining number of receptors, as determined in saturation-binding studies using the selective alpha 2-AR antagonist [3H]rauwolscine in the same membranes. The agonist dissociation constant (KA) derived from EPI-stimulated [35S]GTP gamma S binding via Furchgott analysis was similar to the EC50 of EPI in the same assay, but 40-fold lower than its Ki measured from EPI competition for [3H]rauwolscine-binding sites in the presence of GTP gamma S and Na+. The occupancy-response relationship, calculated using Ki rather than KA, was markedly nonlinear, consistent with the high expression of alpha 2D-AR in these membranes. A nonlinear occupancy-response relationship was more directly confirmed by measuring the maximal level (i.e., full occupancy level) of G protein activation at graded densities of alpha AD-AR after N-ethoxycarbonyl-1,2-dihydroquinoline treatment. Determination of the number of G-proteins activated per receptor yielded lower values at higher receptor densities, indicating that overexpression of receptors can reduce their efficiency. Our results indicate the potential utility of using GTP-binding studies to assess agonist efficacy at the G protein level under conditions where receptor occupation can also be directly measured.
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Affiliation(s)
- W N Tian
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Mass. 02115, USA
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46
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Abstract
alpha 2-adrenoceptor-mediated contractions of the rabbit saphenous vein were previously found to be inhibited by wortmannin, a protein kinase inhibitor which blocks receptor-dependent phospholipase D activation. Since other studies have indicated that receptor-dependent phospholipase D activation required activity of a tyrosine kinase, we examined the influence of several tyrosine kinase inhibitors on both alpha 2-adrenoceptor-mediated contractions of rabbit saphenous vein and alpha 1-adrenoceptor-mediated contractions of rabbit aorta. Methyl 2,5-dihydroxycinnamate, genistein and erbstatin each caused non-competitive inhibition of rabbit saphenous vein contractions elicited by the alpha 2-adrenoceptor-selective agonist 5-bromo-6-[2-imidazolin-2-yl-amino]-quinoxaline (UK14304), yielding complete inhibition at 100 microM and IC50 values of 15, 35 and 40 microM respectively. By contrast, phenylephrine-induced dose-response curves in rabbit aorta were largely unaffected by tyrosine kinase inhibitors at 50 microM. In a separate analysis of intracellular Ca(2+)-dependent and extracellular Ca(2+)-dependent alpha 1-adrenoceptor responses of rabbit aorta, genistein (50 microM) did partially reduce the initial intracellular Ca(2+)-dependent response, but did not reduce maximal response. Methyl 2,5-dihydroxycinnamate (25 microM) had no effect on intracellular or extracellular Ca2+ responses in rabbit aorta. High K(+)-induced contractions of both rabbit saphenous vein and aorta were unaffected by up to 100 microM of the tyrosine kinase inhibitors. These results indicate an obligatory requirement for tyrosine kinase activity in alpha 2-adrenoceptor-mediated but not alpha 1-adrenoceptor-mediated vasoconstriction.
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MESH Headings
- Animals
- Aorta/metabolism
- Brimonidine Tartrate
- Cinnamates/pharmacology
- Dose-Response Relationship, Drug
- Genistein
- Hydroquinones/pharmacology
- Isoflavones/pharmacology
- Male
- Muscle Contraction/drug effects
- Muscle, Smooth, Vascular/drug effects
- Phenylephrine/pharmacology
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/physiology
- Quinoxalines/pharmacology
- Rabbits
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/metabolism
- Saphenous Vein/drug effects
- Saphenous Vein/metabolism
- Vasoconstriction/drug effects
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Affiliation(s)
- A Jinsi
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
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Aburto T, Jinsi A, Zhu Q, Deth RC. Involvement of protein kinase C activation in alpha 2-adrenoceptor-mediated contractions of rabbit saphenous vein. Eur J Pharmacol 1995; 277:35-44. [PMID: 7635171 DOI: 10.1016/0014-2999(95)00054-o] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The role of protein kinase C alpha 2-adrenoceptor-induced contractions of rabbit saphenous vein was investigated. Contractions induced by the alpha 2-adrenoceptor-selective agonist 5-bromo-6-[2-imidazolin-2-ylamino]-quinoline (UK14304) were inhibited by prior treatment with pertussis toxin and by Ca2+ removal, confirming a Gi/Go-dependent coupling pathway which was highly dependent upon Ca2+ influx. Protein kinase C inhibitors calphostin-C and staurosporine each caused a non-competitive inhibition of UK14304 response. Down-regulation of protein kinase C by pretreatment with tetradecanoylphorbol acetate reduced UK14304 response by almost 90% with no effect on contractions induced by elevated KCl. The ineffectiveness of L-type Ca2+ channel blockers and the absence of stimulated 45Ca2+ uptake or efflux by UK14304 indicated that phospholipid-derived products were most likely responsible for protein kinase C activation. alpha 2-Adrenoceptor stimulation failed to increase [3H]myoinositol phosphate formation, but caused a significant increase in the formation of both [32P]phosphatidic acid and diacylglycerol, indicating the possible activation of phospholipase D activity. These results suggest that protein kinase C is important for the vasoconstriction induced by alpha 2-adrenoceptors and that diacylglycerol derived from receptor-initiated phospholipase D activity may provide protein kinase C stimulation.
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Affiliation(s)
- T Aburto
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
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48
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Shi AG, Deth RC. Precoupling of alpha-2B adrenergic receptors and G-proteins in transfected PC-12 cell membranes: influence of pertussis toxin and a lysine-directed cross-linker. J Pharmacol Exp Ther 1994; 271:1520-7. [PMID: 7996466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The ability of pertussis toxin (PTX) pretreatment to alter the binding of [3H]rauwolscine (RAU) to alpha-2B adrenergic receptors expressed in PC12 cells was examined. PTX caused a 30% increase in the Bmax for [3H]RAU and reduced its KD, whereas in the added presence of Na+ and Gpp(NH)p binding was increased to 75% above the level in untreated membranes. Because all three agents act to reduce receptor/G-protein affinity, the increased binding may reflect extensive precoupling of the alpha-2B receptor. The affinity of the agonist epinephrine in displacing [3H]RAU was normally reduced by both Na+ and Gpp(NH)p; however, in PTX-treated membranes the effect of Gpp(NH)p was eliminated, and Na+ remained effective. The lysine-directed cross-linking reagent ethyleneglycol bis(succinimidyl)succinate (EGS) was utilized in an attempt to cross-link precoupled receptor and G-protein. Maximal [3H]RAU binding was reduced by EGS in a time- and dose-dependent manner, and this action was reversed by prior incubation with Na+ and Gpp(NH)p, suggesting that EGS did indeed cross-link receptor and G-protein. RAU and epinephrine each provided protection against the effect of EGS. The inclusion of Na+ and Gpp(NH)p during [3H]RAU binding studies was able to restore maximal binding in EGS-treated membranes to the same level as untreated membranes. These results indicate that in the absence of Na+ and Gpp(NH)p at least 40% of the total alpha-2B adrenergic receptors in these membranes exist as a precoupled receptor/G-protein complex which fails to bind [3H]RAU.
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Affiliation(s)
- A G Shi
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts
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Waen-Safranchik VI, Deth RC. Effects of wortmannin on alpha-1/alpha-2 adrenergic receptor-mediated contractile responses in rabbit vascular tissues. Pharmacology 1994; 48:349-59. [PMID: 8047554 DOI: 10.1159/000139200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The inhibitory effect of wortmannin (WO), a fungus-derived protein kinase inhibitor, was assessed on contractile responses elicited by phenylephrine-induced alpha 1-(alpha 1 R) and UK 14304-induced alpha 2-adrenergic receptor (alpha 2R) stimulation in the rabbit aorta and saphenous vein, respectively. In agonist dose-response studies, WO caused a noncompetitive inhibition of both alpha 1R and alpha 2R responses, but was more potent against alpha 2R. Maximally effective single-dose responses at both receptors were less sensitive to WO. The initial alpha 1R contractile response, associated with intracellular Ca2+ release and myosin light chain kinase activation, was relatively insensitive to WO, while the Ca2+ influx-dependent tonic contraction was more sensitive. Contractions induced by high K+ buffer were relatively insensitive to WO in both the aorta and saphenous vein. These results indicate that WO inhibits receptor-initiated Ca2+ influx-dependent contractile responses such as those caused by alpha 2R stimulation and the sustained phase of alpha 1R stimulation more readily than Ca2+ release-dependent responses.
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Affiliation(s)
- V I Waen-Safranchik
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Mass. 02115
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Tian WN, Duzic E, Lanier SM, Deth RC. Determinants of alpha 2-adrenergic receptor activation of G proteins: evidence for a precoupled receptor/G protein state. Mol Pharmacol 1994; 45:524-31. [PMID: 8145737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The ability of agonist-occupied alpha 2D-adrenergic receptors to activate G proteins was measured in membranes from PC-12 cells stably expressing the cloned receptor, using guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTP gamma S) binding as an endpoint. Epinephrine (EPI) stimulated [35S]GTP gamma S binding in a Mg(2+)-dependent manner, showing both micromolar and millimolar cation affinities. Prior treatment of cells with pertussis toxin completely eliminated the EPI stimulation. The presence of GDP decreased basal [35S]GTP gamma S binding and increased the proportion of EPI-stimulated binding. Increasing concentrations of Na+ also reduced basal [35S]GTP gamma S binding but had less effect on EPI-stimulated binding, such that the agonist response was proportionately greater at higher Na+ levels. In saturation binding studies with [35S]GTP gamma S only low affinity binding was observed in the presence of 100 mM Na+, whereas in the absence of Na+ a high affinity component was also present, indicating a Na(+)-regulated receptor/G protein interaction. EPI induced high affinity [35S]GTP gamma S binding in the presence of Na+ and increased the affinity of the high affinity component under Na(+)-free conditions. The selective alpha 2-adrenergic antagonist rauwolscine produced rightward shifts of EPI dose-response curves and decreased the basal level of [35-S]GTP gamma S binding across the same range of concentrations. The extent of decrease was dependent upon the alpha 2-adrenergic receptor expression level, indicating that alpha 2-adrenergic receptors contribute to basal G protein activation in the absence of agonist. The ability of rauwolscine to decrease basal [35S]GTP gamma S binding was diminished as the level of Na+ was increased, suggesting that both agents act to reduce receptor/G protein interaction, by distinctive mechanisms. alpha 2-Adrenergic receptor antagonists reduced basal G protein activation with a rank order for maximal effectiveness that was different from their receptor binding affinities. These results support the existence of precoupling between alpha 2D-adrenergic receptors and G proteins; coupling can be diminished by both Na+ and antagonists, whereas agonists increase the efficiency of receptor/G protein coupling.
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Affiliation(s)
- W N Tian
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts 02115
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