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Wegiel J, Chadman K, London E, Wisniewski T, Wegiel J. Contribution of the serotonergic system to developmental brain abnormalities in autism spectrum disorder. Autism Res 2024. [PMID: 38500252 DOI: 10.1002/aur.3123] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/28/2024] [Indexed: 03/20/2024]
Abstract
This review highlights a key role of the serotonergic system in brain development and in distortions of normal brain development in early stages of fetal life resulting in cascades of abnormalities, including defects of neurogenesis, neuronal migration, neuronal growth, differentiation, and arborization, as well as defective neuronal circuit formation in the cortex, subcortical structures, brainstem, and cerebellum of autistic subjects. In autism, defects in regulation of neuronal growth are the most frequent and ubiquitous developmental changes associated with impaired neuron differentiation, smaller size, distorted shape, loss of spatial orientation, and distortion of cortex organization. Common developmental defects of the brain in autism include multiregional focal dysplastic changes contributing to local neuronal circuit distortion, epileptogenic activity, and epilepsy. There is a discrepancy between more than 500 reports demonstrating the contribution of the serotonergic system to autism's behavioral anomalies, highlighted by lack of studies of autistic subjects' brainstem raphe nuclei, the center of brain serotonergic innervation, and of the contribution of the serotonergic system to the diagnostic features of autism spectrum disorder (ASD). Discovery of severe fetal brainstem auditory system neuronal deficits and other anomalies leading to a spectrum of hearing deficits contributing to a cascade of behavioral alterations, including deficits of social and verbal communication in individuals with autism, is another argument to intensify postmortem studies of the type and topography of, and the severity of developmental defects in raphe nuclei and their contribution to abnormal brain development and to the broad spectrum of functional deficits and comorbid conditions in ASD.
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Affiliation(s)
- Jarek Wegiel
- Department of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Kathryn Chadman
- Department of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Eric London
- Department of Psychology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Thomas Wisniewski
- Department of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
- Center for Cognitive Neurology, Department of Neurology, Pathology and Psychiatry, NYU Grossman School of Medicine, New York, New York, USA
| | - Jerzy Wegiel
- Department of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
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2
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Torres EB, Varkey H, Vero J, London E, Phan H, Kittler P, Gordon A, Delgado RE, Delgado CF, Simpson EA. Sensing echoes: temporal misalignment in auditory brainstem responses as the earliest marker of neurodevelopmental derailment. PNAS Nexus 2023; 2:pgac315. [PMID: 36798622 PMCID: PMC9927073 DOI: 10.1093/pnasnexus/pgac315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 12/30/2022] [Indexed: 02/16/2023]
Abstract
Neurodevelopmental disorders are on the rise worldwide, with diagnoses that detect derailment from typical milestones by 3 to 4.5 years of age. By then, the circuitry in the brain has already reached some level of maturation that inevitably takes neurodevelopment through a different course. There is a critical need then to develop analytical methods that detect problems much earlier and identify targets for treatment. We integrate data from multiple sources, including neonatal auditory brainstem responses (ABR), clinical criteria detecting autism years later in those neonates, and similar ABR information for young infants and children who also received a diagnosis of autism spectrum disorders, to produce the earliest known digital screening biomarker to flag neurodevelopmental derailment in neonates. This work also defines concrete targets for treatment and offers a new statistical approach to aid in guiding a personalized course of maturation in line with the highly nonlinear, accelerated neurodevelopmental rates of change in early infancy.
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Affiliation(s)
| | - Hannah Varkey
- Psychology Department, Rutgers University, 152 Frelinghuysen Rd., Piscataway, NJ 08854, USA
| | - Joe Vero
- Psychology Department, Rutgers University, 152 Frelinghuysen Rd., Piscataway, NJ 08854, USA
| | - Eric London
- New York State Office for People with Developmental Disabilities (OPWDD), Institute for Basic Research in Developmental Disabilities (IBR), 1050 Forest Hill Rd., Staten Island, NY 10314, USA
| | - Ha Phan
- New York State Office for People with Developmental Disabilities (OPWDD), Institute for Basic Research in Developmental Disabilities (IBR), 1050 Forest Hill Rd., Staten Island, NY 10314, USA
| | - Phyllis Kittler
- New York State Office for People with Developmental Disabilities (OPWDD), Institute for Basic Research in Developmental Disabilities (IBR), 1050 Forest Hill Rd., Staten Island, NY 10314, USA
| | - Anne Gordon
- New York State Office for People with Developmental Disabilities (OPWDD), Institute for Basic Research in Developmental Disabilities (IBR), 1050 Forest Hill Rd., Staten Island, NY 10314, USA
| | - Rafael E Delgado
- Intelligent Hearing Systems Corp, 6860 SW 81st St, Miami, FL, 33143, USA
| | - Christine F Delgado
- Department of Psychology, University of Miami, PO Box 248185, Coral Gables, FL 33124, USA
| | - Elizabeth A Simpson
- Department of Psychology, University of Miami, PO Box 248185, Coral Gables, FL 33124, USA
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3
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London E, Jure R, Gaspar P, Puelles L, Kulesza RJ. Editorial: The role of the brainstem and cerebellum in autism and related neurodevelopmental disorders (DD). Front Integr Neurosci 2022; 16:957003. [PMID: 36118119 PMCID: PMC9471669 DOI: 10.3389/fnint.2022.957003] [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] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 07/27/2022] [Indexed: 11/17/2022] Open
Affiliation(s)
- Eric London
- Institute for Basic Research in Developmental Disabilities (IBR), Staten Island, NY, United States
- *Correspondence: Eric London
| | - Rubin Jure
- Centro Privado de Neurología y Neuropsicología Infanto Juvenil WERNICKE, Cordoba, Argentina
| | | | | | - Randy J. Kulesza
- Lake Erie College of Osteopathic Medicine, Erie, PA, United States
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4
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Dufour BD, Albores-Gallo L, Luna-Muñoz J, Hagerman R, Miquelajauregui A, Buriticá E, Saldarriaga W, Pacheco-Herrero M, Yris Silvestre-Sosa A, Mazefsky C, Gastgeb H, Kofler J, Casanova M, Hof PR, London E, Hagerman P, Martínez-Cerdeño V. Hispano-American Brain Bank on Neurodevelopmental Disorders: An initiative to promote brain banking, research, education, and outreach in the field of neurodevelopmental disorders. Brain Pathol 2021; 32:e13019. [PMID: 34515386 PMCID: PMC8877728 DOI: 10.1111/bpa.13019] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 11/30/2022] Open
Abstract
Neurodevelopmental disorders (NDDs) are conditions that present with brain dysfunction due to alterations in the processes of brain development. They present with neuropsychiatric, cognitive, and motor symptoms. Autism spectrum disorder (ASD) and Fragile X syndrome (FXS) are two of the most common NDDs. Human brain tissue is a scarce resource that is obtained from postmortem donations. In the case of NDDs, specifically autism, the reduced donation rate of brains prevents researchers to investigate its pathology and fine anatomy. The Hispano-American Brain Bank of Neurodevelopmental Disorders (Banco Hispanoamericano de CErebros de trastornos del NEurodesarrollo) or CENE is a large-scale brain bank for neurodevelopmental disorders in Hispano-America and the US. CENE's objectives are to collect and distribute brains of patients with NDDS, with a focus on ASD and FXS, to perform research, promote education of future scientists, and enhance public awareness about the importance of human tissue availability for scientific research on brain function and disease. CENE has thus far established a bilingual system of nodes and teams in several American countries including California-US, Pennsylvania-US, México, Puerto Rico, Colombia, and Dominican Republic. CENE ensures that postmortem NDD samples used in research better match the world's genetic and ethnic diversity. CENE enables and expands NDD brain research worldwide, particularly with respect to ASD and FXS.
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Affiliation(s)
- Brett D Dufour
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, California, USA.,Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children, Sacramento, California, USA
| | - Lilia Albores-Gallo
- Department of Genetic, Clinical, and Community Epidemiology, Hospital Psiquiátrico Infantil "Dr. Juan N. Navarro", Universidad Nacional Autónoma de Mexico, México City, México
| | - Jose Luna-Muñoz
- National Dementia BioBank, Ciencias Biológicas, Facultad de Estudios Superiores, Cuautitlán, Universidad Nacional Autónoma de Mexico, México City, México
| | - Randi Hagerman
- Department of Pediatrics, UC Davis School of Medicine, Sacramento, California, USA.,MIND Institute, UC Davis School of Medicine, Sacramento, California, USA
| | - Amaya Miquelajauregui
- Institute of Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Efrain Buriticá
- Department of Morphology, Centro de Estudios Cerebrales, Faculty of Health, University of Valle, Cali, Colombia
| | | | - Mar Pacheco-Herrero
- Neuroscience Research Laboratory, Faculty of Health Sciences, Pontificia Universidad Católica Madre y Maestra, Santiago de los Caballeros, Dominican Republic
| | | | - Carla Mazefsky
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Holly Gastgeb
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Julia Kofler
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Manuel Casanova
- Department of Biomedical Sciences, School of Medicine Greenville, University of South Carolina, Greenville, South Carolina, USA
| | - Patrick R Hof
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Eric London
- New York State Institute for Basic Research, Staten Island, New York, USA
| | - Paul Hagerman
- MIND Institute, UC Davis School of Medicine, Sacramento, California, USA.,Department of Biochemistry, University of California-Davis Medical Center, Sacramento, California, USA
| | - Verónica Martínez-Cerdeño
- Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, California, USA.,Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children, Sacramento, California, USA.,MIND Institute, UC Davis School of Medicine, Sacramento, California, USA
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5
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Feitosa A, Assunção C, Yoshida T, Sabbag J, Araujo T, London E. Prolonged status epilepticus as a first symptom of a negative antibody autoimmune disease – A case report. J Neurol Sci 2019. [DOI: 10.1016/j.jns.2019.10.799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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6
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Waterhouse L, London E, Gillberg C. The ASD diagnosis has blocked the discovery of valid biological variation in neurodevelopmental social impairment. Autism Res 2019; 10:1182. [PMID: 28714261 DOI: 10.1002/aur.1832] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 06/16/2017] [Indexed: 12/29/2022]
Affiliation(s)
- Lynn Waterhouse
- Professor Graduate Global Program, Director Emeritus, Child Behavior Study, The College of New Jersey, Ewing, NJ, 08628
| | - Eric London
- NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Christopher Gillberg
- Professor of Child and Adolescent Psychiatry, University of Gothenburg, Gothenberg, Sweden
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7
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Webb E, Moon J, Dyrszka L, Rodriguez B, Cox C, Patisaul H, Bushkin S, London E. Neurodevelopmental and neurological effects of chemicals associated with unconventional oil and natural gas operations and their potential effects on infants and children. Rev Environ Health 2018; 33:3-29. [PMID: 29068792 DOI: 10.1515/reveh-2017-0008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/28/2017] [Indexed: 05/05/2023]
Abstract
Heavy metals (arsenic and manganese), particulate matter (PM), benzene, toluene, ethylbenzene, xylenes (BTEX), polycyclic aromatic hydrocarbons (PAHs) and endocrine disrupting chemicals (EDCs) have been linked to significant neurodevelopmental health problems in infants, children and young adults. These substances are widely used in, or become byproducts of unconventional oil and natural gas (UOG) development and operations. Every stage of the UOG lifecycle, from well construction to extraction, operations, transportation and distribution can lead to air and water contamination. Residents near UOG operations can suffer from increased exposure to elevated concentrations of air and water pollutants. Here we focus on five air and water pollutants that have been associated with potentially permanent learning and neuropsychological deficits, neurodevelopmental disorders and neurological birth defects. Given the profound sensitivity of the developing brain and central nervous system, it is reasonable to conclude that young children who experience frequent exposure to these pollutants are at particularly high risk for chronic neurological diseases. More research is needed to understand the extent of these concerns in the context of UOG, but since UOG development has expanded rapidly in recent years, the need for public health prevention techniques, well-designed studies and stronger state and national regulatory standards is becoming increasingly apparent.
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Affiliation(s)
- Ellen Webb
- Center for Environmental Health, 2201 Broadway, Suite 302, Oakland, CA 94612, USA
| | | | - Larysa Dyrszka
- Physicians for Social Responsibility, Glen Spey, NY, USA
| | | | - Caroline Cox
- Center for Environmental Health, Oakland, CA, USA
| | - Heather Patisaul
- North Carolina State University College of Sciences, Raleigh, NC, USA
| | - Sheila Bushkin
- Institute for Health and the Environment, Albany, NY, USA
| | - Eric London
- Institute for Basic Research, New York, NY, USA
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8
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Trampush JW, Yang MLZ, Yu J, Knowles E, Davies G, Liewald DC, Starr JM, Djurovic S, Melle I, Sundet K, Christoforou A, Reinvang I, DeRosse P, Lundervold AJ, Steen VM, Espeseth T, Räikkönen K, Widen E, Palotie A, Eriksson JG, Giegling I, Konte B, Roussos P, Giakoumaki S, Burdick KE, Payton A, Ollier W, Horan M, Chiba-Falek O, Attix DK, Need AC, Cirulli ET, Voineskos AN, Stefanis NC, Avramopoulos D, Hatzimanolis A, Arking DE, Smyrnis N, Bilder RM, Freimer NA, Cannon TD, London E, Poldrack RA, Sabb FW, Congdon E, Conley ED, Scult MA, Dickinson D, Straub RE, Donohoe G, Morris D, Corvin A, Gill M, Hariri AR, Weinberger DR, Pendleton N, Bitsios P, Rujescu D, Lahti J, Le Hellard S, Keller MC, Andreassen OA, Deary IJ, Glahn DC, Malhotra AK, Lencz T. GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium. Mol Psychiatry 2017; 22:1651-1652. [PMID: 29068436 PMCID: PMC5659072 DOI: 10.1038/mp.2017.197] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This corrects the article DOI: 10.1038/mp.2016.244.
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9
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Trampush JW, Yang MLZ, Yu J, Knowles E, Davies G, Liewald DC, Starr JM, Djurovic S, Melle I, Sundet K, Christoforou A, Reinvang I, DeRosse P, Lundervold AJ, Steen VM, Espeseth T, Räikkönen K, Widen E, Palotie A, Eriksson JG, Giegling I, Konte B, Roussos P, Giakoumaki S, Burdick KE, Payton A, Ollier W, Horan M, Chiba-Falek O, Attix DK, Need AC, Cirulli ET, Voineskos AN, Stefanis NC, Avramopoulos D, Hatzimanolis A, Arking DE, Smyrnis N, Bilder RM, Freimer NA, Cannon TD, London E, Poldrack RA, Sabb FW, Congdon E, Conley ED, Scult MA, Dickinson D, Straub RE, Donohoe G, Morris D, Corvin A, Gill M, Hariri AR, Weinberger DR, Pendleton N, Bitsios P, Rujescu D, Lahti J, Le Hellard S, Keller MC, Andreassen OA, Deary IJ, Glahn DC, Malhotra AK, Lencz T. GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium. Mol Psychiatry 2017; 22:336-345. [PMID: 28093568 PMCID: PMC5322272 DOI: 10.1038/mp.2016.244] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 10/30/2016] [Accepted: 11/03/2016] [Indexed: 01/12/2023]
Abstract
The complex nature of human cognition has resulted in cognitive genomics lagging behind many other fields in terms of gene discovery using genome-wide association study (GWAS) methods. In an attempt to overcome these barriers, the current study utilized GWAS meta-analysis to examine the association of common genetic variation (~8M single-nucleotide polymorphisms (SNP) with minor allele frequency ⩾1%) to general cognitive function in a sample of 35 298 healthy individuals of European ancestry across 24 cohorts in the Cognitive Genomics Consortium (COGENT). In addition, we utilized individual SNP lookups and polygenic score analyses to identify genetic overlap with other relevant neurobehavioral phenotypes. Our primary GWAS meta-analysis identified two novel SNP loci (top SNPs: rs76114856 in the CENPO gene on chromosome 2 and rs6669072 near LOC105378853 on chromosome 1) associated with cognitive performance at the genome-wide significance level (P<5 × 10-8). Gene-based analysis identified an additional three Bonferroni-corrected significant loci at chromosomes 17q21.31, 17p13.1 and 1p13.3. Altogether, common variation across the genome resulted in a conservatively estimated SNP heritability of 21.5% (s.e.=0.01%) for general cognitive function. Integration with prior GWAS of cognitive performance and educational attainment yielded several additional significant loci. Finally, we found robust polygenic correlations between cognitive performance and educational attainment, several psychiatric disorders, birth length/weight and smoking behavior, as well as a novel genetic association to the personality trait of openness. These data provide new insight into the genetics of neurocognitive function with relevance to understanding the pathophysiology of neuropsychiatric illness.
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Affiliation(s)
- J W Trampush
- Division of Psychiatry Research, Zucker Hillside Hospital, Glen Oaks, NY, USA
| | - M L Z Yang
- Institute of Mental Health, Singapore, Singapore
| | - J Yu
- Division of Psychiatry Research, Zucker Hillside Hospital, Glen Oaks, NY, USA,Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, Manhasset, NY, USA
| | - E Knowles
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - G Davies
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK,Department of Psychology, University of Edinburgh, Edinburgh, UK
| | - D C Liewald
- Department of Psychology, University of Edinburgh, Edinburgh, UK
| | - J M Starr
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK,Alzheimer Scotland Dementia Research Centre, University of Edinburgh, Edinburgh, UK
| | - S Djurovic
- Department of Medical Genetics, Oslo University Hospital, University of Bergen, Oslo, Norway,NORMENT, K.G. Jebsen Centre for Psychosis Research, University of Bergen, Bergen, Norway
| | - I Melle
- NORMENT, K.G. Jebsen Centre for Psychosis Research, University of Bergen, Bergen, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - K Sundet
- Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway,Department of Psychology, University of Oslo, Oslo, Norway
| | - A Christoforou
- NORMENT, K.G. Jebsen Centre for Psychosis Research, University of Bergen, Bergen, Norway,Dr Einar Martens Research Group for Biological Psychiatry, Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - I Reinvang
- Department of Psychology, University of Oslo, Oslo, Norway
| | - P DeRosse
- Division of Psychiatry Research, Zucker Hillside Hospital, Glen Oaks, NY, USA,Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, Manhasset, NY, USA
| | - A J Lundervold
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
| | - V M Steen
- NORMENT, K.G. Jebsen Centre for Psychosis Research, University of Bergen, Bergen, Norway,Dr Einar Martens Research Group for Biological Psychiatry, Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - T Espeseth
- Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway,Department of Psychology, University of Oslo, Oslo, Norway
| | - K Räikkönen
- Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland
| | - E Widen
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - A Palotie
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland,Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK,Department of Medical Genetics, University of Helsinki and University Central Hospital, Helsinki, Finland
| | - J G Eriksson
- National Institute for Health and Welfare, Helsinki, Finland,Department of General Practice and Primary Health Care, University of Helsinki, Helsinki, Finland,Helsinki University Central Hospital, Unit of General Practice, Helsinki, Finland,Folkhälsan Research Centre, Helsinki, Finland
| | - I Giegling
- Department of Psychiatry, Martin Luther University of Halle-Wittenberg, Halle, Germany
| | - B Konte
- Department of Psychiatry, Martin Luther University of Halle-Wittenberg, Halle, Germany
| | - P Roussos
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA,Department of Genetics and Genomic Science and Institute for Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA,Mental Illness Research, Education, and Clinical Center (VISN 3), James J. Peters VA Medical Center, Bronx, NY, USA
| | - S Giakoumaki
- Department of Psychology, University of Crete, Rethymno, Greece
| | - K E Burdick
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA,Mental Illness Research, Education, and Clinical Center (VISN 3), James J. Peters VA Medical Center, Bronx, NY, USA
| | - A Payton
- Manchester Centre for Audiology and Deafness, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK,Division of Evolution and Genomic Sciences, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - W Ollier
- Centre for Integrated Genomic Medical Research, Institute of Population Health, University of Manchester, Manchester, UK
| | - M Horan
- Manchester Medical School, Institute of Brain, Behaviour, and Mental Health, University of Manchester, Manchester, UK
| | - O Chiba-Falek
- Department of Neurology, Bryan Alzheimer's Disease Research Center, and Center for Genomic and Computational Biology, Duke University Medical Center, Durham, NC, USA
| | - D K Attix
- Department of Neurology, Bryan Alzheimer's Disease Research Center, and Center for Genomic and Computational Biology, Duke University Medical Center, Durham, NC, USA,Division of Medical Psychology, Department of Neurology, Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - A C Need
- Division of Brain Sciences, Department of Medicine, Imperial College, London, UK
| | - E T Cirulli
- Center for Applied Genomics and Precision Medicine, Duke University School of Medicine, Durham, NC, USA
| | - A N Voineskos
- Campbell Family Mental Health Institute, Centre for Addiction and Mental Health, University of Toronto, Toronto, ON, Canada
| | - N C Stefanis
- Department of Psychiatry, University of Athens School of Medicine, Eginition Hospital, Athens, Greece,University Mental Health Research Institute, Athens, Greece,Neurobiology Research Institute, Theodor Theohari Cozzika Foundation, Athens, Greece
| | - D Avramopoulos
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA,Department of Psychiatry and McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - A Hatzimanolis
- Department of Psychiatry, University of Athens School of Medicine, Eginition Hospital, Athens, Greece,University Mental Health Research Institute, Athens, Greece,Neurobiology Research Institute, Theodor Theohari Cozzika Foundation, Athens, Greece
| | - D E Arking
- Department of Psychiatry and McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - N Smyrnis
- Department of Psychiatry, University of Athens School of Medicine, Eginition Hospital, Athens, Greece,University Mental Health Research Institute, Athens, Greece
| | - R M Bilder
- UCLA Semel Institute for Neuroscience and Human Behavior, Los Angeles, CA, USA
| | - N A Freimer
- UCLA Semel Institute for Neuroscience and Human Behavior, Los Angeles, CA, USA
| | - T D Cannon
- Department of Psychology, Yale University, New Haven, CT, USA
| | - E London
- UCLA Semel Institute for Neuroscience and Human Behavior, Los Angeles, CA, USA
| | - R A Poldrack
- Department of Psychology, Stanford University, Palo Alto, CA, USA
| | - F W Sabb
- Robert and Beverly Lewis Center for Neuroimaging, University of Oregon, Eugene, OR, USA
| | - E Congdon
- UCLA Semel Institute for Neuroscience and Human Behavior, Los Angeles, CA, USA
| | | | - M A Scult
- Department of Psychology & Neuroscience, Laboratory of NeuroGenetics, Duke University, Durham, NC, USA
| | - D Dickinson
- Clinical and Translational Neuroscience Branch, Intramural Research Program, National Institute of Mental Health, National Institute of Health, Bethesda, MD, USA
| | - R E Straub
- Lieber Institute for Brain Development, Johns Hopkins University Medical Campus, Baltimore, MD, USA
| | - G Donohoe
- Department of Psychology, National University of Ireland, Galway, Ireland
| | - D Morris
- Department of Psychiatry, Neuropsychiatric Genetics Research Group, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - A Corvin
- Department of Psychiatry, Neuropsychiatric Genetics Research Group, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - M Gill
- Department of Psychiatry, Neuropsychiatric Genetics Research Group, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - A R Hariri
- Department of Psychology & Neuroscience, Laboratory of NeuroGenetics, Duke University, Durham, NC, USA
| | - D R Weinberger
- Lieber Institute for Brain Development, Johns Hopkins University Medical Campus, Baltimore, MD, USA
| | - N Pendleton
- Centre for Integrated Genomic Medical Research, Institute of Population Health, University of Manchester, Manchester, UK,Manchester Medical School, Institute of Brain, Behaviour, and Mental Health, University of Manchester, Manchester, UK
| | - P Bitsios
- Department of Psychiatry and Behavioral Sciences, Faculty of Medicine, University of Crete, Heraklion, Greece
| | - D Rujescu
- Department of Psychiatry, Martin Luther University of Halle-Wittenberg, Halle, Germany
| | - J Lahti
- Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland,Helsinki Collegium for Advanced Studies, University of Helsinki, Helsinki, Finland
| | - S Le Hellard
- NORMENT, K.G. Jebsen Centre for Psychosis Research, University of Bergen, Bergen, Norway,Dr Einar Martens Research Group for Biological Psychiatry, Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - M C Keller
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA
| | - O A Andreassen
- NORMENT, K.G. Jebsen Centre for Psychosis Research, University of Bergen, Bergen, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - I J Deary
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK,Department of Psychology, University of Edinburgh, Edinburgh, UK
| | - D C Glahn
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - A K Malhotra
- Division of Psychiatry Research, Zucker Hillside Hospital, Glen Oaks, NY, USA,Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, Manhasset, NY, USA,Department of Psychiatry, Hofstra Northwell School of Medicine, Hempstead, NY, USA
| | - T Lencz
- Division of Psychiatry Research, Zucker Hillside Hospital, Glen Oaks, NY, USA,Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, Manhasset, NY, USA,Department of Psychiatry, Hofstra Northwell School of Medicine, Hempstead, NY, USA,Division of Psychiatry Research, Zucker Hillside Hospital, 75-59 263rd Street, Glen Oaks, NY 11004, USA. E-mail:
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10
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Abstract
Abstract
ASD research is at an important crossroads. The ASD diagnosis is important for assigning a child to early behavioral intervention and explaining a child’s condition. But ASD research has not provided a diagnosis-specific medical treatment, or a consistent early predictor, or a unified life course. If the ASD diagnosis also lacks biological and construct validity, a shift away from studying ASD-defined samples would be warranted. Consequently, this paper reviews recent findings for the neurobiological validity of ASD, the construct validity of ASD diagnostic criteria, and the construct validity of ASD spectrum features. The findings reviewed indicate that the ASD diagnosis lacks biological and construct validity. The paper concludes with proposals for research going forward.
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11
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Wegiel J, Flory M, Schanen NC, Cook EH, Nowicki K, Kuchna I, Imaki H, Ma SY, Wegiel J, London E, Casanova MF, Wisniewski T, Brown WT. Significant neuronal soma volume deficit in the limbic system in subjects with 15q11.2-q13 duplications. Acta Neuropathol Commun 2015; 3:63. [PMID: 26463344 PMCID: PMC4603300 DOI: 10.1186/s40478-015-0241-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 09/24/2015] [Indexed: 11/23/2022] Open
Abstract
Introduction Autism is diagnosed in numerous genetic and genomic developmental disorders associated with an overlap in high-risk genes and loci that underlie intellectual disability (ID) and epilepsy. The aim of this stereological study of neuronal soma volume in 25 brain structures and their subdivisions in eight individuals 9 to 26 years of age who were diagnosed with chromosome 15q11.2-13.1 duplication syndrome [dup(15)], autism, ID and epilepsy; eight age-matched subjects diagnosed with autism of unknown etiology (idiopathic autism) and seven control individuals was to establish whether defects of neuronal soma growth are a common denominator of developmental pathology in idiopathic and syndromic autism and how genetic modifications alter the trajectory of neuronal soma growth in dup(15) autism. Results Application of the Nucleator software to estimate neuronal size revealed significant neuronal soma volume deficits in 11 of 25 structures and their subregions (44 %) in subjects diagnosed with dup(15) autism, including consistent neuronal soma volume deficits in the limbic system (sectors CA2, 3 and 4 in Ammon’s horn, the second and third layers of the entorhinal cortex and in the amygdala), as well as in the thalamus, nucleus accumbens, external globus pallidus, and Ch3 nucleus in the magnocellular basal complex, and in the inferior olive in the brainstem. The second feature distinguishing dup(15) autism was persistent neuronal soma deficits in adolescents and young adults, whereas in idiopathic autism, neuronal volume deficit is most prominent in 4- to 8-year-old children but affects only a few brain regions in older subjects. Conclusions This study demonstrates that alterations in the trajectory of neuronal growth throughout the lifespan are a core pathological features of idiopathic and syndromic autism. However, dup(15) causes persistent neuronal volume deficits in adolescence and adulthood, with prominent neuronal growth deficits in all major compartments of the limbic system. The more severe neuronal nuclear and cytoplasic volume deficits in syndromic autism found in this study and the more severe focal developmental defects in the limbic system in dup(15) previously reported in this cohort may contribute to the high prevalence of early onset intractable epilepsy and sudden unexpected death in epilepsy.
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12
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Wegiel J, Flory M, Kuchna I, Nowicki K, Ma SY, Imaki H, Wegiel J, Frackowiak J, Kolecka BM, Wierzba-Bobrowicz T, London E, Wisniewski T, Hof PR, Brown WT. Neuronal nucleus and cytoplasm volume deficit in children with autism and volume increase in adolescents and adults. Acta Neuropathol Commun 2015; 3:2. [PMID: 25595448 PMCID: PMC4302585 DOI: 10.1186/s40478-015-0183-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 01/01/2015] [Indexed: 11/22/2022] Open
Abstract
Introduction Characterization of the type and topography of structural changes and their alterations throughout the lifespan of individuals with autism is essential for understanding the mechanisms contributing to the autistic phenotype. The aim of this stereological study of neurons in 16 brain structures of 14 autistic and 14 control subjects from 4 to 64 years of age was to establish the course of neuronal nuclear and cytoplasmic volume changes throughout the lifespan of individuals with autism. Results Our data indicate that a deficit of neuronal soma volume in children with autism is associated with deficits in the volume of the neuronal nucleus and cytoplasm. The significant deficits of neuronal nuclear and cytoplasmic volumes in 13 of 16 examined subcortical structures, archicortex, cerebellum, and brainstem in 4- to 8-year-old autistic children suggest a global nature of brain developmental abnormalities, but with region-specific differences in the severity of neuronal pathology. The observed increase in nuclear volumes in 8 of 16 structures in the autistic teenagers/young adults and decrease in nuclear volumes in 14 of 16 regions in the age-matched control subjects reveal opposite trajectories throughout the lifespan. The deficit in neuronal nuclear volumes, ranging from 7% to 42% in the 16 examined regions in children with autism, and in neuronal cytoplasmic volumes from 1% to 31%, as well as the broader range of interindividual differences for the nuclear than the cytoplasmic volume deficits, suggest a partial distinction between nuclear and cytoplasmic pathology. Conclusions The most severe deficit of both neuronal nucleus and cytoplasm volume in 4-to 8-year-old autistic children appears to be a reflection of early developmental alterations that may have a major contribution to the autistic phenotype. The broad range of functions of the affected structures implies that their developmental and age-associated abnormalities contribute not only to the diagnostic features of autism but also to the broad spectrum of clinical alterations associated with autism. Lack of clinical improvement in autistic teenagers and adults indicates that the observed increase in neuron nucleus and cytoplasm volume close to control level does not normalize brain function.
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13
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London E, Lodish M, Keil M, Lyssikatos C, de la Luz Sierra M, Nesterova M, Stratakis CA. Not all glucocorticoid-induced obesity is the same: differences in adiposity among various diagnostic groups of Cushing syndrome. Horm Metab Res 2014; 46:897-903. [PMID: 25295416 DOI: 10.1055/s-0034-1389956] [Citation(s) in RCA: 3] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The cAMP signaling pathway is implicated in bilateral adrenocortical hyperplasias (BAHs), which are often associated with ACTH-independent Cushing syndrome (CS). Although CS is invariably associated with obesity and is frequently associated with PKA signaling defects, we recently reported that its different forms appear to also present with variable weight gain and adiposity. The present study was aimed at characterizing further the phenotypic and molecular differences in periadrenal adipose tissue (PAT) among patients with subtypes of CS, by anthropometric/biochemical analyses and quantification of PKA expression and activity in BAHs in comparison to a non-CS group with aldosterone producing adenomas (APAs). Glucocorticoid levels, serum parameters, and BMI were analyzed among a larger patient cohort including those with different forms of CS, APAs, and Cushing disease. Abdominal CT scans were available for a small subset of patients examined for fat distribution. PAT collected during adrenalectomy was assayed for PKA activity, cAMP, and PKA expression. BMI and BMI z-score were lower in adults with PPNAD with PRKAR1A mutations and in pediatric patients with PPNAD with and without PRKAR1A mutations, respectively. Patients with PPNAD had higher cAMP levels in PAT and different fat distribution. Thus, PKA activity in PAT differed between CS diagnostic groups. Increased cAMP and PKA activity may have contributed to phenotypic differences among subtypes of CS. In agreement with the known roles of cAMP signaling in the regulation of adiposity, patients with PPNAD were less obese than other patients with CS.
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Affiliation(s)
- E London
- Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Bethesda, MD, USA
| | - M Lodish
- Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Bethesda, MD, USA
| | - M Keil
- Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Bethesda, MD, USA
| | - C Lyssikatos
- Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Bethesda, MD, USA
| | - M de la Luz Sierra
- Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Bethesda, MD, USA
| | - M Nesterova
- Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Bethesda, MD, USA
| | - C A Stratakis
- Section on Endocrinology & Genetics, Program on Developmental Endocrinology & Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Bethesda, MD, USA
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14
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Wegiel J, Flory M, Kuchna I, Nowicki K, Ma SY, Imaki H, Wegiel J, Cohen IL, London E, Wisniewski T, Brown WT. Stereological study of the neuronal number and volume of 38 brain subdivisions of subjects diagnosed with autism reveals significant alterations restricted to the striatum, amygdala and cerebellum. Acta Neuropathol Commun 2014; 2:141. [PMID: 25231243 PMCID: PMC4177256 DOI: 10.1186/s40478-014-0141-7] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 09/09/2014] [Indexed: 01/18/2023] Open
Abstract
Introduction A total of 38 brain cytoarchitectonic subdivisions, representing subcortical and cortical structures, cerebellum, and brainstem, were examined in 4- to 60-year-old subjects diagnosed with autism and control subjects (a) to detect a global pattern of developmental abnormalities and (b) to establish whether the function of developmentally modified structures matches the behavioral alterations that are diagnostic for autism. The volume of cytoarchitectonic subdivisions, neuronal numerical density, and total number of neurons per region of interest were determined in 14 subjects with autism and 14 age-matched controls by using unbiased stereological methods. Results The study revealed that significant differences between the group of subjects with autism and control groups are limited to a few brain regions, including the cerebellum and some striatum and amygdala subdivisions. In the group of individuals with autism, the total number and numerical density of Purkinje cells in the cerebellum were reduced by 25% and 24%, respectively. In the amygdala, significant reduction of neuronal density was limited to the lateral nucleus (by 12%). Another sign of the topographic selectivity of developmental alterations in the brain of individuals with autism was an increase in the volumes of the caudate nucleus and nucleus accumbens by 22% and 34%, respectively, and the reduced numerical density of neurons in the nucleus accumbens and putamen by 15% and 13%, respectively. Conclusions The observed pattern of developmental alterations in the cerebellum, amygdala and striatum is consistent with the results of magnetic resonance imaging studies and their clinical correlations, and of some morphometric studies that indicate that detected abnormalities may contribute to the social and communication deficits, and repetitive and stereotypical behaviors observed in individuals with autism.
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15
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Wegiel J, Flory M, Kuchna I, Nowicki K, Ma SY, Imaki H, Wegiel J, Cohen IL, London E, Brown WT, Wisniewski T. Brain-region-specific alterations of the trajectories of neuronal volume growth throughout the lifespan in autism. Acta Neuropathol Commun 2014; 2:28. [PMID: 24612906 PMCID: PMC4007529 DOI: 10.1186/2051-5960-2-28] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 02/21/2014] [Indexed: 01/17/2023] Open
Abstract
Several morphometric studies have revealed smaller than normal neurons in the neocortex of autistic subjects. To test the hypothesis that abnormal neuronal growth is a marker of an autism-associated global encephalopathy, neuronal volumes were estimated in 16 brain regions, including various subcortical structures, Ammon's horn, archicortex, cerebellum, and brainstem in 14 brains from individuals with autism 4 to 60 years of age and 14 age-matched control brains. This stereological study showed a significantly smaller volume of neuronal soma in 14 of 16 regions in the 4- to 8-year-old autistic brains than in the controls. Arbitrary classification revealed a very severe neuronal volume deficit in 14.3% of significantly altered structures, severe in 50%, moderate in 21.4%, and mild in 14.3% structures. This pattern suggests desynchronized neuronal growth in the interacting neuronal networks involved in the autistic phenotype. The comparative study of the autistic and control subject brains revealed that the number of structures with a significant volume deficit decreased from 14 in the 4- to 8-year-old autistic subjects to 4 in the 36- to 60-year-old. Neuronal volumes in 75% of the structures examined in the older adults with autism are comparable to neuronal volume in age-matched controls. This pattern suggests defects of neuronal growth in early childhood and delayed up-regulation of neuronal growth during adolescence and adulthood reducing neuron soma volume deficit in majority of examined regions. However, significant correction of neuron size but limited clinical improvements suggests that delayed correction does not restore functional deficits.
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Affiliation(s)
- Jerzy Wegiel
- Department of Developmental Neurobiology, NYS Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA
| | - Michael Flory
- Department of Infant Development, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Izabela Kuchna
- Department of Developmental Neurobiology, NYS Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA
| | - Krzysztof Nowicki
- Department of Developmental Neurobiology, NYS Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA
| | - Shuang Yong Ma
- Department of Developmental Neurobiology, NYS Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA
| | - Humi Imaki
- Department of Developmental Neurobiology, NYS Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA
| | - Jarek Wegiel
- Department of Developmental Neurobiology, NYS Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314, USA
| | - Ira L Cohen
- Department of Psychology, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Eric London
- Department of Psychology, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - W Ted Brown
- Department of Human Genetics, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Thomas Wisniewski
- Department of Psychiatry, Neurology and Pathology, New York University School of Medicine, New York, NY, USA
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Wegiel J, Kuchna I, Nowicki K, Imaki H, Wegiel J, Ma SY, Azmitia EC, Banerjee P, Flory M, Cohen IL, London E, Brown WT, Komich Hare C, Wisniewski T. Contribution of olivofloccular circuitry developmental defects to atypical gaze in autism. Brain Res 2013; 1512:106-22. [PMID: 23558308 DOI: 10.1016/j.brainres.2013.03.037] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 02/11/2013] [Accepted: 03/19/2013] [Indexed: 10/27/2022]
Abstract
Individuals with autism demonstrate atypical gaze, impairments in smooth pursuit, altered movement perception and deficits in facial perception. The olivofloccular neuronal circuit is a major contributor to eye movement control. This study of the cerebellum in 12 autistic and 10 control subjects revealed dysplastic changes in the flocculus of eight autistic (67%) and two control (20%) subjects. Defects of the oculomotor system, including avoidance of eye contact and poor or no eye contact, were reported in 88% of autistic subjects with postmortem-detected floccular dysplasia. Focal disorganization of the flocculus cytoarchitecture with deficit, altered morphology, and spatial disorientation of Purkinje cells (PCs); deficit and abnormalities of granule, basket, stellate and unipolar brush cells; and structural defects and abnormal orientation of Bergmann glia are indicators of profound disruption of flocculus circuitry in a dysplastic area. The average volume of PCs was 26% less in the dysplastic region than in the unaffected region of the flocculus (p<0.01) in autistic subjects. Moreover, the average volume of PCs in the entire cerebellum was 25% less in the autistic subjects than in the control subjects (p<0.001). Findings from this study and a parallel study of the inferior olive (IO) suggest that focal floccular dysplasia combined with IO neurons and PC developmental defects may contribute to oculomotor system dysfunction and atypical gaze in autistic subjects.
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Affiliation(s)
- Jerzy Wegiel
- Department of Developmental Neurobiology, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, United States.
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17
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Wegiel J, Schanen NC, Cook EH, Sigman M, Brown WT, Kuchna I, Nowicki K, Wegiel J, Imaki H, Ma SY, Marchi E, Wierzba-Bobrowicz T, Chauhan A, Chauhan V, Cohen IL, London E, Flory M, Lach B, Wisniewski T. Differences between the pattern of developmental abnormalities in autism associated with duplications 15q11.2-q13 and idiopathic autism. J Neuropathol Exp Neurol 2012; 71:382-97. [PMID: 22487857 PMCID: PMC3612833 DOI: 10.1097/nen.0b013e318251f537] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The purposes of this study were to identify differences in patterns of developmental abnormalities between the brains of individuals with autism of unknown etiology and those of individuals with duplications of chromosome 15q11.2-q13 (dup[15]) and autism and to identify alterations that may contribute to seizures and sudden death in the latter. Brains of 9 subjects with dup(15), 10 with idiopathic autism, and 7 controls were examined. In the dup(15) cohort, 7 subjects (78%) had autism, 7 (78%) had seizures, and 6 (67%) had experienced sudden unexplained death. Subjects with dup(15) autism were microcephalic, with mean brain weights 300 g less (1,177 g) than those of subjects with idiopathic autism (1,477 g; p<0.001). Heterotopias in the alveus, CA4, and dentate gyrus and dysplasia in the dentate gyrus were detected in 89% of dup(15) autism cases but in only 10% of idiopathic autism cases (p < 0.001). By contrast, cerebral cortex dysplasia was detected in 50% of subjects with idiopathic autism and in no dup(15) autism cases (p<0.04). The different spectrum and higher prevalence of developmental neuropathologic findings in the dup(15) cohort than in cases with idiopathic autism may contribute to the high risk of early onset of seizures and sudden death.
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Affiliation(s)
- Jerzy Wegiel
- Department of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA.
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18
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Karmel BZ, Gardner JM, Meade LS, Cohen IL, London E, Flory MJ, Lennon EM, Miroshnichenko I, Rabinowitz S, Parab S, Barone A, Harin A. Early medical and behavioral characteristics of NICU infants later classified with ASD. Pediatrics 2010; 126:457-67. [PMID: 20679296 PMCID: PMC3494479 DOI: 10.1542/peds.2009-2680] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVES Recent evidence suggests higher prevalence of autism spectrum disorder (ASD) in NICU graduates. This aim of this study was to identify retrospectively early behaviors found more frequently in NICU infants who went on to develop ASD. METHODS Twenty-eight NICU graduates who later received a diagnosis of ASD were compared with 2169 other NICU graduates recruited from 1994 to 2005. They differed in gender, gestational age, and birth cohort. These characteristics were used to draw a matched control sample (n=112) to determine which, if any, early behaviors discriminated subsequent ASD diagnosis. Behavioral testing at targeted ages (adjusted for gestation) included the Rapid Neonatal Neurobehavioral Assessment (hospital discharge, 1 month), Arousal-Modulated Attention (hospital discharge, 1 and 4 months), and Bayley Scales of Infant Development (multiple times, 4-25 months). RESULTS At 1 month, children with ASD but not control children had persistent neurobehavioral abnormalities and higher incidences of asymmetric visual tracking and arm tone deficits. At 4 months, children with ASD had continued visual preference for higher amounts of stimulation than did control children, behaving more like newborns. Unlike control children, children with ASD had declining mental and motor performance by 7 to 10 months, resembling infants with severe central nervous system involvement. CONCLUSIONS Differences in specific behavior domains between NICU graduates who later receive a diagnosis of ASD and matched NICU control children may be identified in early infancy. Studies with this cohort may provide insights to help understand and detect early disabilities, including ASD.
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Affiliation(s)
- Bernard Z Karmel
- New York State Institute for Basic Research in Developmental Disabilities, Department of Infant Development, 1050 Forest Hill Rd, Staten Island, NY 10314, USA.
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Wegiel J, Kuchna I, Nowicki K, Imaki H, Wegiel J, Marchi E, Ma SY, Chauhan A, Chauhan V, Bobrowicz TW, de Leon M, Louis LAS, Cohen IL, London E, Brown WT, Wisniewski T. The neuropathology of autism: defects of neurogenesis and neuronal migration, and dysplastic changes. Acta Neuropathol 2010; 119:755-70. [PMID: 20198484 PMCID: PMC2869041 DOI: 10.1007/s00401-010-0655-4] [Citation(s) in RCA: 402] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 02/05/2010] [Accepted: 02/09/2010] [Indexed: 12/20/2022]
Abstract
Autism is characterized by a broad spectrum of clinical manifestations including qualitative impairments in social interactions and communication, and repetitive and stereotyped patterns of behavior. Abnormal acceleration of brain growth in early childhood, signs of slower growth of neurons, and minicolumn developmental abnormalities suggest multiregional alterations. The aim of this study was to detect the patterns of focal qualitative developmental defects and to identify brain regions that are prone to developmental alterations in autism. Formalin-fixed brain hemispheres of 13 autistic (4–60 years of age) and 14 age-matched control subjects were embedded in celloidin and cut into 200-μm-thick coronal sections, which were stained with cresyl violet and used for neuropathological evaluation. Thickening of the subependymal cell layer in two brains and subependymal nodular dysplasia in one brain is indicative of active neurogenesis in two autistic children. Subcortical, periventricular, hippocampal and cerebellar heterotopias detected in the brains of four autistic subjects (31%) reflect abnormal neuronal migration. Multifocal cerebral dysplasia resulted in local distortion of the cytoarchitecture of the neocortex in four brains (31%), of the entorhinal cortex in two brains (15%), of the cornu Ammonis in four brains and of the dentate gyrus in two brains. Cerebellar flocculonodular dysplasia detected in six subjects (46%), focal dysplasia in the vermis in one case, and hypoplasia in one subject indicate local failure of cerebellar development in 62% of autistic subjects. Detection of flocculonodular dysplasia in only one control subject and of a broad spectrum of focal qualitative neuropathological developmental changes in 12 of 13 examined brains of autistic subjects (92%) reflects multiregional dysregulation of neurogenesis, neuronal migration and maturation in autism, which may contribute to the heterogeneity of the clinical phenotype.
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Zhao G, London E. Behavior of Diphtheria Toxin T Domain Containing Substitutions That Block Normal Membrane Insertion at Pro345 and Leu307: Control of Deep Membrane Insertion and Coupling between Deep Insertion of Hydrophobic Subdomains. Biochemistry 2008. [DOI: 10.1021/bi800558r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Until recently, autism, along with the other developmental disabilities, was largely ignored by the medical and research community. At this early point in our understanding of the syndrome, neurobiologists and especially those who work with human brain tissue have a great deal to offer. A thorough understanding of the clinically defined syndrome is essential. Along with the other psychiatric diseases listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM), autism is defined by gross behavioral macros that, in all probability, are only indirectly related to basic biological systems. The diagnostic schema is not etiologically based. The diagnostic triad of symptoms that defines autism--impaired communication, impaired social interaction, and restricted and repetitive interests and activities--has been found to be present in the general population with no clear demarcation between pathological severity and being a common trait. In addition, the three basic symptoms of autism appear not to associate highly, thus leaving undetermined the validity of studying autism in its currently defined triad of symptoms. It is proposed that a close working relationship between neurobiologists and clinicians is necessary in order to identify etiologically based diagnostic schemas that would complement, rather than replace, the clinical diagnosis.
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Affiliation(s)
- Eric London
- Department of Psychology, Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA.
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22
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London E, Haroutunian V. SYMPOSIUM: Neurobiology of Autism—Introduction. Brain Pathol 2007. [DOI: 10.1111/j.1750-3639.2007.00106.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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Mengesha D, London E, Parsons E, Moore J, Castonguay T. WITHDRAWN: 11 β hydroxysteroid dehydrogenase-1 and obesity. Appetite 2006. [DOI: 10.1016/j.appet.2006.03.269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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24
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Chefer S, Kimes A, Domino E, London E, Mukhin A. Estimation of D2-like dopamine receptor occupancy by dopamine in the MPTP primate model of Parkinson's disease. Neuroimage 2006. [DOI: 10.1016/j.neuroimage.2006.04.127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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25
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Abstract
Presented is a review of recent progress in the understanding of autism based on investigations of donated human brain tissue. Autism is a pervasive developmental disorder by the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria, manifesting by age 3 and characterized by impairments in social interaction and communication, as well as restricted, repetitive, stereotyped patterns of behavior. Based on reported neuropathologic findings, these characteristic behaviors are clinical manifestations of both pre- and postnatal alterations. This review summarizes the current data obtained from postmortem brain studies in the areas of stereology, neurotransmitter systems/synaptic processes, molecular mechanisms, and neuroimmunology. In addition, we discuss current research strategies designed to facilitate translational research and maximize the yield of precious resources (e.g. the Autism Tissue Program), highlight barriers to research, and consider future trends.
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Affiliation(s)
- Jane Pickett
- Autism Tissue Program, Princeton, NJ 08540, USA.
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26
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Abstract
We describe two patients in whom poor healing after chemical ablation for ingrown toenails unmasked significant vascular disease of the lower extremities. We have found no similar reports in the English language literature.
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Affiliation(s)
- M Toybenshlak
- Hadassah-Hebrew University Center, Jerusalem, Israel
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27
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Abstract
The first iron-dextran complex was discovered in 1953, when we attempted to synthesize an analog of ferritin, by substituting polysaccharide for its protein shell. This new complex soon became the most widely used parental therapy for hypochromic anemia in humans. No molecular formula has been proposed, but Cox has attributed an outline structure to it. The present article proposes a structure greatly different from the Cox model, by having a polynuclear beta-ferric oxyhydroxide core, closely similar or identical to Akaganeite, chelated firmly by an encircling framework of dextran gluconic acid chains and surrounded by a removable outer sheath of colloidal dextran gluconic acid. The molecular weight of the iron-dextran core molecule, including its chelated framework, has been determined by gel filtration and analysis and its molecular formula (1.3) calculated. Also, these new data and existing electron photomicrographic, X-ray diffraction and crystallographic studies, have enabled a molecular weight, formula, and model structure to be proposed for its complex (2), which includes the outer sheath. The 480 iron atoms in both the core molecule and its sheathed complex are close to the number calculated from the core's unit cell dimensions and volume.
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Affiliation(s)
- E London
- School of Pharmacy and Biomedical Sciences, St. Michael's Building, White Swan Road, University of Portsmouth, Portsmouth, PO1 2DT, UK.
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28
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Abstract
Subtalar distraction bone block arthrodesis has been described to treat late complications of displaced calcaneal fractures. A "ramp cage" can be used to restore the talocalcaneal relationship by providing stable correction in the coronal and sagittal dimensions.
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Affiliation(s)
- I Zion
- Department of Orthopedic Surgery, Foot and Ankle Service, Hadassah Medical Center, Hebrew University, Jerusalem, Israel
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29
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Xu X, Bittman R, Duportail G, Heissler D, Vilcheze C, London E. Effect of the structure of natural sterols and sphingolipids on the formation of ordered sphingolipid/sterol domains (rafts). Comparison of cholesterol to plant, fungal, and disease-associated sterols and comparison of sphingomyelin, cerebrosides, and ceramide. J Biol Chem 2001; 276:33540-6. [PMID: 11432870 DOI: 10.1074/jbc.m104776200] [Citation(s) in RCA: 446] [Impact Index Per Article: 19.4] [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: 11/06/2022] Open
Abstract
Ordered lipid domains enriched in sphingolipids and cholesterol (lipid rafts) have been implicated in numerous functions in biological membranes. We recently found that lipid domain/raft formation is dependent on the sterol component having a structure that allows tight packing with lipids having saturated acyl chains (Xu, X., and London, E. (2000) Biochemistry 39, 844-849). In this study, the domain-promoting activities of various natural sterols were compared with that of cholesterol using both fluorescence quenching and detergent insolubility methods. Using model membranes, it was shown that, like cholesterol, both plant and fungal sterols promote the formation of tightly packed, ordered lipid domains by lipids with saturated acyl chains. Surprisingly ergosterol, a fungal sterol, and 7-dehydrocholesterol, a sterol present in elevated levels in Smith-Lemli-Opitz syndrome, were both significantly more strongly domain-promoting than cholesterol. Domain formation was also affected by the structure of the sphingolipid (or that of an equivalent "saturated" phospholipid) component. Sterols had pronounced effects on domain formation by sphingomyelin and dipalmitoylphosphatidylcholine but only a weak influence on the ability of cerebrosides to form domains. Strikingly it was found that a small amount of ceramide (3 mol %) significantly stabilized domain/raft formation. The molecular basis for, and the implications of, the effects of different sterols and sphingolipids (especially ceramide) on the behavior and biological function of rafts are discussed.
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Affiliation(s)
- X Xu
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook, Stony Brook, New York 11794-5215, USA
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30
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Affiliation(s)
- E London
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook 11794-5215, USA
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31
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London E, Brown DA. Insolubility of lipids in triton X-100: physical origin and relationship to sphingolipid/cholesterol membrane domains (rafts). Biochim Biophys Acta 2000; 1508:182-95. [PMID: 11090825 DOI: 10.1016/s0304-4157(00)00007-1] [Citation(s) in RCA: 534] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The insolubility of lipids in detergents is a useful method for probing the structure of biological membranes. Insolubility in detergents like Triton X-100 is observed in lipid bilayers that exist in physical states in which lipid packing is tight. The Triton X-100-insoluble lipid fraction obtained after detergent extraction of eukaryotic cells is composed of detergent-insoluble membranes rich in sphingolipids and cholesterol. These insoluble membranes appear to arise from sphingolipid- and cholesterol-rich membrane domains (rafts) in the tightly packed liquid ordered state. Because the degree of lipid insolubility depends on the stability of lipid-lipid interactions relative to lipid-detergent interactions, the quantitative relationship between rafts and detergent-insoluble membranes is complex, and can depend on lipid composition, detergent and temperature. Nevertheless, when used conservatively detergent insolubility is an invaluable tool for studying cellular rafts and characterizing their composition.
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Affiliation(s)
- E London
- Department of Biochemistry, State University of New York at Stony Brook, New York 11794-5215, USA.
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32
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Galynker II, Watras-Ganz S, Miner C, Rosenthal RN, Des Jarlais DC, Richman BL, London E. Cerebral metabolism in opiate-dependent subjects: effects of methadone maintenance. Mt Sinai J Med 2000; 67:381-7. [PMID: 11064488] [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] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
BACKGROUND The long-term effects of opiate use on human brain are not known. The goal of this preliminary study was to determine whether human subjects with histories of opiate dependence have persistent differences in brain function as compared with individuals without substance use disorders, and whether methadone maintenance reverses or ameliorates the potential abnormality. METHOD Positron emission tomographic (PET) [18F]fluorodeoxyglucose (FDG) method was used to compare the regional cerebral metabolic rate for glucose(rCMRglc) in three groups: four opiate-dependent subjects currently receiving methadone maintenance therapy (MM), four opiate-dependent subjects not receiving methadone maintenance therapy (MW), and a comparison group of five subjects without substance use disorders. RESULTS A significant difference in rCMRglc in the anterior cingulate gyrus was found between the MW and Control groups (Mann-Whitney U=2.0, p=0.05). Generally speaking, rCMRglc's in MM subjects were intermediate between those of MW and Control groups, although the difference did not reach statistical significance. CONCLUSIONS The results of this study suggest that neurobiological abnormalities can persist in the brain of a chronic opiate user several years after detoxification from methadone. Future research is needed to replicate these results and to determine whether the observed rCMRglc differences are related to opiate use or to neurochemical abnormalities that play a role in developing addictive behavior.
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Affiliation(s)
- I I Galynker
- Department of Psychiatry, Beth Israel Medical Center, First Avenue at 16th Street, New York, NY 10003, USA
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33
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Lew S, Ren J, London E. The effects of polar and/or ionizable residues in the core and flanking regions of hydrophobic helices on transmembrane conformation and oligomerization. Biochemistry 2000; 39:9632-40. [PMID: 10933779 DOI: 10.1021/bi000694o] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [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: 11/29/2022]
Abstract
To explore the influence of amino acid composition on the behavior of membrane-inserted alpha-helices, we examined the behavior of Lys-flanked polyleucyl (pLeu) helices containing a single polar/ionizable residue within their hydrophobic core. To evaluate the location of the helices within the membrane by fluorescence, each contained a Trp residue at the center of the sequence. When incorporated into dioleoylphosphatidylcholine (DOPC) model membrane vesicles, pLeu helices with or without a single Ser, Asn, Lys, or Asp residue in the hydrophobic core maintained a transmembrane state (named the N state) at neutral and acidic pH. In this state, the central Trp exhibited highly blue-shifted fluorescence, and fluorescence quenching by nitroxide-labeled lipids showed it located at the bilayer center. A state in which Trp fluorescence red-shifted by several nanometers (named the B state) was observed above pH 10-11. B state formation appears to result from deprotonation of the flanking Lys residues. Despite the red shift in Trp emission, fluorescence quenching showed that in the B state the Trp at most is only slightly shallower than in the N state, suggesting the B state also is a transmembrane or near-transmembrane structure. The B state is characterized by increased helix oligomerization, as shown by the dependence of Trp lambda(max) on the concentration of the peptide within the bilayer at high pH. The pLeu peptide with a Asp residue in the core underwent a pH-dependent transition at a lower pH than the other peptides (pH 8-9). At high pH, it exhibited both a more highly red-shifted fluorescence and shallower Trp location than the other peptides. This state (named the S state) did not exhibit a concentration-dependent Trp lambda(max). We attribute S state behavior to the formation of a charged Asp residue at high pH, and a consequent movement of the Asp toward the membrane surface, resulting in the formation of a nontransmembrane state. We conclude that a polar or ionizable residue can readily be tolerated in a single transmembrane helix, but that the charges on ionizable residues in the core and regions flanking the helix significantly modulate the stability of transmembrane insertion and/or helix-helix association.
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Affiliation(s)
- S Lew
- Department of Biochemistry and Cell Biology and Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-5215, USA
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34
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Affiliation(s)
- D A Brown
- Departments of Biochemistry and Cell Biology and Chemistry, State University of New York, Stony Brook, New York 11794-5215, USA.
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35
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Wollstein R, Wolf Y, Sklair-Levy M, Matan Y, London E, Nyska M. Obliteration of a late traumatic posterior tibial artery pseudoaneurysm by duplex compression. J Trauma 2000; 48:1156-8. [PMID: 10866266 DOI: 10.1097/00005373-200006000-00025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- R Wollstein
- Department of Orthopedic Surgery, Hadassah University Hospital, Mount Scopus and Ein Karem, Jerusalem, Israel
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36
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Abstract
Detergent-insoluble membrane domains, enriched in saturated lipids and cholesterol, have been implicated in numerous biological functions. To understand how cholesterol promotes domain formation, the effect of various sterols and sterol derivatives on domain formation in mixtures of the saturated lipid dipalmitoylphosphatidylcholine (DPPC) and a fluorescence quenching analogue of an unsaturated lipid was compared. Quenching measurements demonstrated that several sterols (cholesterol, dihydrocholesterol, epicholesterol, and 25-hydroxycholesterol) promote formation of DPPC-enriched domains. Other sterols and sterol derivatives had little effect on domain formation (cholestane and lanosterol) or, surprisingly, strongly inhibit it (coprostanol, androstenol, cholesterol sulfate, and 4-cholestenone). The effect of sterols on domain formation was closely correlated with their effects on DPPC insolubility. Those sterols that promoted domain formation increased DPPC insolubility, whereas those sterols that inhibit domain formation decreased DPPC insolubility. The effects of sterols on the fluorescence polarization of diphenylhexatriene incorporated into DPPC-containing vesicles were also correlated with sterol structure. These experiments indicate that the effect of sterol on the ability of saturated lipids to form a tightly packed (i.e., tight in the sense that the lipids are closely packed with one another) and ordered state is the key to their effect on domain formation. Those sterols that promote tight packing of saturated lipids promote domain formation, while those sterols that inhibited tight packing of saturated lipids inhibited domain formation. The ability of some sterols to inhibit domain formation (i.e., act as "anti-cholesterols") should be a valuable tool for examining domain formation and properties in cells.
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Affiliation(s)
- X Xu
- Department of Biochemistry and Cell Biology and Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-5215, USA
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37
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Abstract
The formation of pores by membrane-inserted diphtheria toxin is closely linked to the translocation of its catalytic chain across membranes. In this report a number of aromatic polyanionic molecules were identified that inhibit toxin-induced leakage of molecules from model membrane vesicles. One inhibitor, Cibacron blue, totally blocked pore formation. Aniline blue and Fast Green decreased the size of the molecule released by a given concentration of toxin. Amaranth appeared to reduce the maximal amount of leakage, without greatly affecting the size of the molecule released at a given toxin concentration. Finally, Ponceau S and Cibacron brilliant red appeared to exhibit a mixture of these various types of inhibition. The inhibitors neither prevented the conformational transition of the toxin to form a hydrophobic state at low pH, nor (with the exception of Cibacron Brilliant Red) appeared to strongly inhibit toxin binding to model membranes. Additional experiments showed release of trapped materials from model membranes by isolated T domain of the toxin was similar to that by whole toxin. The effects of inhibitors on T domain induced release was also similar to that they have on whole toxin. Therefore, it is likely that the inhibition of pore formation by whole toxin involves inhibitor interaction with the T domain. The inhibitors identified in this study may be helpful for development of agents that interfere with toxin action in vivo.
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Affiliation(s)
- J C Sharpe
- Department of Biochemistry and Cell Biology SUNY at Stony Brook, NY 11794-5215, USA
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38
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Sharpe JC, London E. Diphtheria toxin forms pores of different sizes depending on its concentration in membranes: probable relationship to oligomerization. J Membr Biol 1999; 171:209-21. [PMID: 10501829 DOI: 10.1007/s002329900572] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [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: 11/28/2022]
Abstract
Diphtheria toxin forms pores in biological and model membranes upon exposure to low pH. These pores may play a critical role in the translocation of the A chain of the toxin into the cytoplasm. The effect of protein concentration on diphtheria toxin pore formation in model membrane systems was assayed by using a new fluorescence quenching method. In this method, the movement of Cascade Blue labeled dextrans of various sizes across membranes is detected by antibodies which quench Cascade Blue fluorescence. It was found that at low pH the toxin makes pores in phosphatidylcholine/phosphatidylglycerol vesicles with a size that depends on protein concentration. At the lowest toxin concentrations only the entrapped free fluorophore (MW 538) could be released from model membranes. At intermediate toxin concentrations, a 3 kD dextran could be released. At the highest toxin concentration, a 10 kD dextran could be released, but not a 70 kD dextran. Similar pore properties were found using vesicles lacking phosphatidylglycerol or containing 30% cholesterol. However, larger pores formed at lower protein concentrations in the presence of cholesterol. The dependence of pore size on toxin concentration suggests that toxin oligomerization regulates pore size. This behavior may explain some of the conflicting data on the size of the pores formed by diphtheria toxin. The formation of oligomers by membrane-inserted toxin is consistent with the results of chemical crosslinking and measurements of the self-quenching of rhodamine-labeled toxin. Based on these experiments we propose diphtheria toxin forms oligomers with a variable stoichiometry, and that pore size depends on the oligomerization state. Reasons why oligomerization could assist proper membrane insertion of the toxin and other proteins that convert from soluble to membrane-inserted states are discussed.
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Affiliation(s)
- J C Sharpe
- Department of Biochemistry and Cell Biology, Department of Chemistry, and the Institute for Cell and Developmental Biology, State University of New York at Stony Brook, Stony Brook, NY 11794-5215, USA
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39
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Ren J, Kachel K, Kim H, Malenbaum SE, Collier RJ, London E. Interaction of diphtheria toxin T domain with molten globule-like proteins and its implications for translocation. Science 1999; 284:955-7. [PMID: 10320374 DOI: 10.1126/science.284.5416.955] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.8] [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: 11/02/2022]
Abstract
The transmembrane (T) domain of diphtheria toxin has a critical role in the low pH-induced translocation of the catalytic domain (A chain) of the toxin across membranes. Here it is shown that at low pH, addition of proteins in a partly unfolded, molten globule-like conformation converted the T domain from a shallow membrane-inserted form to its transmembrane form. Fluorescence energy transfer demonstrated that molten globule-like proteins bound to the T domain. Thus, the T domain recognizes proteins that are partly unfolded and may function in translocation of the A chain as a transmembrane chaperone.
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Affiliation(s)
- J Ren
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook, Stony Brook, NY 11794, USA
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40
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Ren J, Lew S, Wang J, London E. Control of the transmembrane orientation and interhelical interactions within membranes by hydrophobic helix length. Biochemistry 1999; 38:5905-12. [PMID: 10231543 DOI: 10.1021/bi982942a] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.8] [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: 11/29/2022]
Abstract
We examined the effect of the length of the hydrophobic core of Lys-flanked poly(Leu) peptides on their behavior when inserted into model membranes. Peptide structure and membrane location were assessed by the fluorescence emission lambdamax of a Trp residue in the center of the peptide sequence, the quenching of Trp fluorescence by nitroxide-labeled lipids (parallax analysis), and circular dichroism. Peptides in which the hydrophobic core varied in length from 11 to 23 residues were found to be largely alpha-helical when inserted into the bilayer. In dioleoylphosphatidylcholine (diC18:1PC) bilayers, a peptide with a 19-residue hydrophobic core exhibited highly blue-shifted fluorescence, an indication of Trp location in a nonpolar environment, and quenching localized the Trp to the bilayer center, an indication of transmembrane structure. A peptide with an 11-residue hydrophobic core exhibited emission that was red-shifted, suggesting a more polar Trp environment, and quenching showed the Trp was significantly displaced from the bilayer center, indicating that this peptide formed a nontransmembranous structure. A peptide with a 23-residue hydrophobic core gave somewhat red-shifted fluorescence, but quenching demonstrated the Trp was still close to the bilayer center, consistent with a transmembrane structure. Analogous behavior was observed when the behavior of individual peptides was examined in model membranes with various bilayer widths. Other experiments demonstrated that in diC18:1PC bilayers the dilution of the membrane concentration of the peptide with a 23-residue hydrophobic core resulted in a blue shift of fluorescence, suggesting the red-shifted fluorescence at higher peptide concentrations was due to helix oligomerization. The intermolecular self-quenching of rhodamine observed when the peptide was rhodamine-labeled, and the concentration dependence of self-quenching, supported this conclusion. These studies indicate that the mismatch between helix length and bilayer width can control membrane location, orientation, and helix-helix interactions, and thus may mismatch control both membrane protein folding and the interactions between membrane proteins.
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Affiliation(s)
- J Ren
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook 11794-5215, USA
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41
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Affiliation(s)
- E London
- Department of Surgery, University of California, Davis, Medical Center, Sacramento 95817, USA
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42
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Ren J, Sharpe JC, Collier RJ, London E. Membrane translocation of charged residues at the tips of hydrophobic helices in the T domain of diphtheria toxin. Biochemistry 1999; 38:976-84. [PMID: 9893993 DOI: 10.1021/bi981576s] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [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: 11/29/2022]
Abstract
The low pH triggered membrane insertion of the T domain of diphtheria toxin is a critical step in the translocation of the C domain of the toxin across membranes in vivo. We previously established that the T domain can interact with membranes in two distinct conformations, one in which the TH8/TH9 helical hairpin lies close to the bilayer surface and a second in which it inserts more deeply and appears to be transmembraneous. The loss of charge on residues E349 and D352 due to protonation at low pH has been proposed to be a critical step in transmembrane insertion, because they are within a loop connecting TH8 and TH9, and must cross the membrane upon transmembrane insertion. In this report, the role of these residues was examined by measuring the effect of the double substitution E349K/D352K on the conformation of the TH8/TH9 hairpin through a fluorescent group attached to TH9. At pH 4.5, there was shallower insertion of TH8/TH9 of the E349K/D352K mutant relative to T domain with wild-type residues at 349 and 352. In addition, smaller and/or fewer pores were obtained with the E349K/D352K mutant relative to the wild-type. On the other hand, high T domain concentrations, or further decreasing pH, allowed transmembrane insertion of both the wild-type and the 349K/352K mutant as well as induction of larger and/or more numerous pores. Furthermore, the transmembrane insertion process was rapid for both the mutant and wild-type. This shows that the mutant has the capacity to form a transmembrane structure similar to that of the wild-type T domain and, thus, that introduction of charged groups in membrane-penetrating regions of a protein does not introduce an insurmountable barrier to transmembrane movement. The linkage between the ability of the T domain to form the transmembrane conformation and pores suggests that the effects of these mutations in inhibiting pore formation are likely to partly result from the inability to insert properly. Additionally, the observation that decreasing pH allows the 349K/352K mutant to insert deeply indicates that there are residues other than E349 and D352 whose protonation promotes transmembrane insertion.
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Affiliation(s)
- J Ren
- Department of Biochemistry and Cell Biology, S.U.N.Y. at Stony Brook 11794-5215, USA
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43
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Abstract
Recent studies showing that detergent-resistant membrane fragments can be isolated from cells suggest that biological membranes are not always in a liquid-crystalline phase. Instead, sphingolipid and cholesterol-rich membranes such as plasma membranes appear to exist, at least partially, in the liquid-ordered phase or a phase with similar properties. Sphingolipid and cholesterol-rich domains may exist as phase-separated "rafts" in the membrane. We discuss the relationship between detergent-resistant membranes, rafts, caveolae, and low-density plasma membrane fragments. We also discuss possible functions of lipid rafts in membranes. Signal transduction through the high-affinity receptor for IgE on basophils, and possibly through related receptors on other hematopoietic cells, appears to be enhanced by association with rafts. Raft association may also aid in signaling through proteins anchored by glycosylphosphatidylinositol, particularly in hematopoietic cells and neurons. Rafts may also function in sorting and trafficking through the secretory and endocytic pathways.
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Affiliation(s)
- D A Brown
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook 11794-5215, USA.
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44
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Abstract
The membrane insertion and translocation of diphtheria toxin, which is induced in vivo by low pH, is thought to be directed by the hydrophobic alpha-helices of its transmembrane (T) domain. In this study the structure of membrane-associated T domain was examined. Site-directed mutants of the T domain with single Trp residues were prepared at the two naturally occurring positions, 206 (near the N-terminal end of helix TH1) and 281 (within helix TH5), as well as at three residues in helix TH9, in which the substitutions F355W (near the N-terminal end of TH9), I364W (close to the center of TH9), and Y375W (near the C-terminal end of TH9) were made. All these mutants were found to undergo the low-pH-induced conformational change observed with wild-type T domain and insert into model membranes at low pH. The location of Trp residues relative to the lipid bilayer was characterized in model membrane vesicles by fluorescence emission and by quenching with nitroxide-labeled phospholipids. In TH9, residue 375 was shallowly inserted, residue 364 deeply inserted, and residue 355 located at an intermediate depth. Residues 206 and 281 exhibited moderately deep insertion. It was also found, in agreement with our previous study using bimane-labeled protein (Wang et al. (1997) J. Biol. Chem. 272, 25091-25098), that TH9 switches from a relatively shallowly inserted state to a more deeply inserted state when the concentration of the T domain in the membrane is increased or the thickness of the membrane bilayer is decreased. In particular, the depth of residue 355 was found to increase under the conditions giving deeper insertion. In contrast, residue 375 remained shallowly located in both states, as predicted from its location on the polar C-terminus of TH9. It is concluded that TH1 and TH5 insert into the lipid bilayer in both T domain conformations. In addition, Trp depths suggest that even in the shallowly inserted state there is a significant degree of insertion of TH9. These results suggest regions of the T domain in addition to the hydrophobic TH8/TH9 hairpin insert into membranes. Models for the structure of the membrane-inserted T domain are discussed.
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Affiliation(s)
- S E Malenbaum
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook 11794-5215, USA
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45
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Kaiser RD, London E. Determination of the depth of BODIPY probes in model membranes by parallax analysis of fluorescence quenching. Biochim Biophys Acta 1998; 1375:13-22. [PMID: 9767081 DOI: 10.1016/s0005-2736(98)00127-8] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The location of a series of lipophilic and lipid-attached BODIPY (4, 4-difluoro-4-bora-3a,4a-diaza-s-indacene) membrane probes was analyzed by the quenching of BODIPY fluorescence by a series of nitroxide-labeled lipids in which the depth of the nitroxide group is varied. When attached to the polar headgroup of PE the BODIPY remained near the polar headgroup in depth. However, when attached at the end of free or phospholipid-attached fatty acyl chains, or when attached to two hydrocarbon chains, we observed two probe populations. One, usually dominant, population of BODIPY groups 'looped back' towards the surface, but a second population remained deeply embedded within the bilayer. When attached to a fatty acid or fatty acyl chain, the deep population appeared to locate at a depth related to its point of attachment to the acyl chain. In BODIPY linked to free fatty acids, the location of the deep population responded to the ionization of the carboxyl group. Because, unlike NBD (7-nitro-2,1,3-benzoxadiazol-4-yl) and most dansyl groups, acyl chain linked BODIPY groups can exist in a deeply buried form we conclude that BODIPY linked acyl chains are superior to NBD or dansyl linked acyl chains as membrane probes.
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Affiliation(s)
- R D Kaiser
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook, Stony Brook, New York 11794-5215, USA
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46
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Malenbaum SE, Merrill AR, London E. Membrane-inserted colicin E1 channel domain: a topological survey by fluorescence quenching suggests that model membrane thickness affects membrane penetration. J Nat Toxins 1998; 7:269-90. [PMID: 9783264] [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] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The topography of the closed-state membrane-associated, colicin E1 channel domain was examined using depth-dependent fluorescence quenching to determine the membrane location of various single Trp residues introduced into the sequence by site-directed mutagenesis. We have extended previous studies (Palmer, L. R., and Merrill, A. R. (1994) J. Biol. Chem. 269, 4187-4193) with additional single Trp residues in the helix 8/9 region, and with an additional quencher located in the polar region of the membrane to detect shallowly located Trp residues. Quenching data for seven single Trp mutants examined in the previous study, but without the shallow quencher, confirmed the previously reported depths. Mutants containing single Trp at residues 355, 460, or 507 were found to be more shallowly located than those at 404, 443, 484, or 495. In addition, analysis of fluorescence in the presence of the shallow quencher eliminated the possibility that there is a predominant population of these residues residing near the membrane-aqueous interface. The fluorescence quenching of three new single Trp at residues 478, 492, or 499 introduced into the channel domain was also evaluated. These residues were found at either medium or deep locations in the bilayer. Of special interest was the position of the Trp at residue 492 (W492), which is within the loop region connecting hydrophobic helices 8 and 9. If helices 8 and 9 were fully transmembraneous, then the predicted W492 location would have been shallow. Instead the quenching pattern demonstrated W492 to be deeply embedded in the lipid bilayer. We also studied the effect of altering bilayer width on protein conformation. Membrane width had little effect on most residues, but Trp at residues 478 and 507 were located more shallowly in thin bilayers. We also examined the effect of bilayer width on the position of Cys 505 labeled with bimane, an environmentally sensitive fluorophore. As the membrane width was decreased, C505-bimane shifted into a more nonpolar environment, as judged by fluorescence emission lambda max and quenching. Models for the conformation of helices 8/9 and the effect of membrane width on these helices are considered. We conclude that helices 8 and 9 probably do not adopt a fully transmembraneous state under the conditions examined in this report.
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Affiliation(s)
- S E Malenbaum
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook 11794-5215, USA
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Abstract
The location of commonly used charged fluorescent membrane probes in membranes was determined in order to: (1) investigate the relationship between the structure of hydrophobic molecules and their depth within membranes; and (2) aid interpretation of experiments in which these fluorescent probes are used to examine membrane structure. Membrane depth was calculated using parallax analysis, a method in which the quenching induced by lipids carrying a nitroxide group at different locations in the membrane is compared. Shallow locations were found for xanthene dyes (fluorescein, eosin, Texas Red and rhodamine) both in free form and when attached either to the headgroup of phospholipids or long hydrocarbon chains. The exact structure of the xanthene and the nature of its linkage to lipid had only a modest effect on membrane location, which ranged between 19 and 24 A from the center of the bilayer in a charged state. Thus, the location of these fluorophores largely reflects their intrinsic properties rather than the nature of the groups to which they are attached. Furthermore, cationic and anionic xanthene derivatives had similar depths, indicating the type of charge does not have a large effect on depth. Consistent with this conclusion, shallow locations were also found for other hydrocarbon chain-linked cationic (acridine orange and styrylpyridinium) and anionic (coumarin, anilinonaphthalenesulfonic acid (ANS), and toluidinylnaphthalenesulfonic acid (TNS)) charged probes. These all located at 16-18 A from the bilayer center. We conclude that both anionic and cationic molecules that are otherwise hydrophobic predominantly occupy shallow locations within the polar headgroup region of the bilayer no matter how hydrophobic the molecule to which they are linked. This depth is significantly shallower than that occupied by most previously studied uncharged polar molecules that locate near the membrane surface. Consistent with this conclusion, a 2-4 A deeper location was found for xanthene probes with no net charge. In other experiments, methods to avoid chemical reactions that can distort the measurement of depth by fluorescence quenching were developed.
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Affiliation(s)
- K Kachel
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook, 11794-5215, USA
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Kachel K, Ren J, Collier RJ, London E. Identifying transmembrane states and defining the membrane insertion boundaries of hydrophobic helices in membrane-inserted diphtheria toxin T domain. J Biol Chem 1998; 273:22950-6. [PMID: 9722516 DOI: 10.1074/jbc.273.36.22950] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [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: 11/06/2022] Open
Abstract
The membrane topography of proteins that convert between soluble and membrane-inserted states has proven a challenging problem. In particular, it has been difficult to define both whether a transmembrane orientation is achieved and what are the boundaries of membrane-inserted segments. In this report the fluorescence of bimane-labeled Cys residues and the binding of anti-BODIPY antibodies to BODIPY-labeled Cys residues are combined to define these features for helices TH8 and TH9 of the T domain of diphtheria toxin. Using a series of labeled residues the topography of these helices was examined in both conformations of membrane-inserted T domain identified previously (Wang, Y., Malenbaum, S. E., Kachel, K., Zhan, H., Collier, R. J., and London, E. (1997) J. Biol. Chem. 272, 25091-25098). In the shallowly inserted conformation these helices are found to be aligned close to the cis surface of the bilayer all along their sequences. In contrast, in the more deeply inserted conformation most TH8 and TH9 residues examined located in a non-polar environment, with the boundaries of the membrane-inserted sequences close to residues 324 and 372-374 on the cis (insertion) side of the bilayer. It was also found that residues 348 and 349, which are in the loop connecting TH8 and TH9, reached the opposite trans side of the bilayer, but did not protrude fully into the aqueous environment. These boundaries suggest the membrane-inserted segments of TH8 and TH9 form transmembrane helices about 25 residues in length, and suggest that they are connected by a tight turn. It is concluded that this combination of fluorescent techniques can be combined to obtain transmembrane helix topography.
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Affiliation(s)
- K Kachel
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
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Affiliation(s)
- D A Brown
- Department of Biochemistry and Cell Biology, Institute for Cell and Developmental Biology, State University of New York at Stony Brook, Stony Brook, NY 11794-5215, USA
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Kaiser RD, London E. Location of diphenylhexatriene (DPH) and its derivatives within membranes: comparison of different fluorescence quenching analyses of membrane depth. Biochemistry 1998; 37:8180-90. [PMID: 9609714 DOI: 10.1021/bi980064a] [Citation(s) in RCA: 280] [Impact Index Per Article: 10.8] [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: 02/07/2023]
Abstract
The average membrane location of a series of diphenylhexatriene (DPH)-derived membrane probes was analyzed by measuring the quenching of DPH fluorescence with a series of nitroxide-labeled lipids in which the depth of the nitroxide group is varied. All DPH derivatives were located deeply within the bilayer. Some derivatives were anchored at a shallower depth than free DPH by attachment to cationic or anionic groups. However, the absolute change in DPH depth upon attachment to such groups was relatively modest (<4 A). In fact, protonated DPH fatty acid and a DPH fatty acyl group attached to a phosphatidylcholine were found to locate slightly more deeply than free DPH. The location of DPH derivatives can be explained by the length of the DPH group and its tendency to orient predominantly parallel to the fatty acyl chains of the bilayer. These factors allow a charged group attached to one end of a DPH molecule to be accommodated at the polar surface while maintaining a deep DPH location. Basically, it appears that most DPH derivatives probe the same region in the bilayer. We conclude previously reported differences in fluorescence polarization of free and anchored forms of DPH may reflect a direct effect of anchoring on motion rather than an effect on average DPH location. Other experiments showed the localization of DPH probes was found to be similar in the presence and absence of cholesterol. This implies that previously observed cholesterol-induced effects on DPH fluorescence polarization also largely reflect differences in DPH motion, not DPH location. From the quenching results it was also possible to define rules governing the location of a variety of chemical groups in membranes by comparison of the results obtained with DPH derivatives to those of similar derivatives of other fluorescent groups. Finally, an important goal of this study was to compare different methods of analysis of quenching data: parallax analysis, distribution (Gaussian) analysis (using a single Gaussian), and a second-order polynomial analysis. To evaluate the accuracy of these methods, the apparent depths of a series of fluorescence probes previously analyzed by parallax analysis was reanalyzed with all three methods. There was good agreement unless the fluorescent molecule was very shallow or very deep. In such cases, only parallax analysis gave physically reasonable results. This is likely to be due to the lack of a sufficient number of quenchers spanning a wide enough range for other analyses to compensate for deviations from ideal curves. Parallax analysis was also compared to distribution (Gaussian) analysis using a double Gaussian fit to account for quenching from the trans leaflet (Ladokhin, A. (1997) Methods Enzymol. 278, 462-473). Again more physically reasonable results were obtained from parallax analysis, likely due to non-Gaussian behavior of the depth dependence of quenching. Notwithstanding these observations, the significant number of cases where Gaussian curve fitting methods for quenching analysis are most powerful are discussed.
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Affiliation(s)
- R D Kaiser
- Department of Biochemistry, State University of New York at Stony Brook 11794-5215, USA
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