University of Massachusetts Medical School eScholarship@UMMS GSBS Dissertations and Theses Graduate School of Biomedical Sciences 2011-05-27 Inflammation Alters Histone Methylation in the Central Nervous System: Implications for Neuropsychiatric Disease: A Dissertation Caroline M. Connor University of Massachusetts Medical School Let us know how access to this document benefits ou.y Follow this and additional works at: https://escholarship.umassmed.edu/gsbs_diss Part of the Amino Acids, Peptides, and Proteins Commons, Bacterial Infections and Mycoses Commons, Cells Commons, Genetic Phenomena Commons, Maternal and Child Health Commons, Mental Disorders Commons, Nervous System Commons, Neuroscience and Neurobiology Commons, and the Pathological Conditions, Signs and Symptoms Commons Repository Citation Connor CM. (2011). Inflammation Alters Histone Methylation in the Central Nervous System: Implications for Neuropsychiatric Disease: A Dissertation. GSBS Dissertations and Theses. https://doi.org/10.13028/ 9s7h-s649. Retrieved from https://escholarship.umassmed.edu/gsbs_diss/542 This material is brought to you by eScholarship@UMMS. It has been accepted for inclusion in GSBS Dissertations and Theses by an authorized administrator of eScholarship@UMMS. For more information, please contact [email protected]. INFLAMMATION ALTERS HISTONE METHYLATION IN CENTRAL NERVOUS SYSTEM: IMPLICATIONS FOR NEUROPSYCHIATRIC DISEASE A Dissertation Presented By Caroline Martine Connor Submitted to the Faculty of the University of Massachusetts Graduate School of Biomedical Sciences Worcester, Massachusetts in partial fulfillment for the requirements for the degree of DOCTOR OF PHILOSOPHY May 27, 2011 Program in Neuroscience ii INFLAMMATION ALTERS HISTONE METHYLATION IN CENTRAL NERVOUS SYSTEM: IMPLICATIONS FOR NEUROPSYCHIATRIC DISEASE A Dissertation Presented By Caroline Martine Connor The signatures of the Dissertation Defense Committee signifies completion and approval as to style and content of the Dissertation __________________________________________ Schahram Akbarian, MD/PhD, Thesis Advisor __________________________________________ Charles Sagerstrom, PhD, Member of Committee __________________________________________ David Paydarfar, MD/PhD, Member of Committee __________________________________________ David Weaver, PhD, Member of Committee __________________________________________ Thomas Kemper, MD, Member of Committee The signature of the Chair of the Committee signifies that the written dissertation meets the requirements of the Dissertation Committee __________________________________________ Job Dekker, PhD, Chair of Committee The signature of the Dean of the Graduate School of Biomedical Sciences signifies that the student has met all graduation requirements of the school. __________________________________________ Anthony Carruthers, PhD, Dean of the Graduate School of Biomedical Sciences Program in Neuroscience May 27, 2011 iii ABSTRACT Maternal infection during pregnancy is associated with increased risk of both schizophrenia and autism in offspring. Based on this observation, the maternal immune activation mouse model was developed, in which pregnant rodents are treated with immune-activating agents and the brains and behavior of the adult offspring studied. This model has been found to recapitulate a variety of molecular, cellular, and behavioral abnormalities observed in both schizophrenia and autism. However, despite the abundant evidence provided by these studies that prenatal exposure to inflammation alters brain development and function later in life, the molecular mechanisms by which inflammation mediates these effects remains unclear. It has been suggested that other prenatal risk factors for neuropsychiatric disease may alter brain development, in part, via epigenetic mechanisms such as DNA methylation and histone modification. However, a link between inflammation and epigenetic modification in brain has not been established. Therefore, the focus of my thesis was to examine the effect of inflammation on the histone modification, trimethylated histone H3 lysine 4 (H3K4me3), which has been implicated in both normal brain development and in schizophrenia. In Chapter II, I describe experiments examining the effect of a specific, cytokine, interleukin-6 (IL-6), on H3K4me3 in rat forebrain culture. I show that IL-6 treatment results in altered levels of H3K4me3 at multiple gene iv promoters, frequently in conjunction with altered mRNA expression levels, and demonstrate that a subset of these alterations appear to be dependent on signaling via the signal transducer and activator of transcription 3 (Stat3) pathway. Furthermore, some of the genes affected by IL-6 also showed altered H3K4me3 levels in autism postmortem brain. Though a direct link still remains to be established, this observation suggests that epigenetic changes observed in neuropsychiatric disease may have been induced by prenatal exposure to inflammation. In Chapter III, I describe in vivo experiments employing the maternal immune activation (MIA) mouse model to examine the effects of prenatal inflammation on H3K4me3 in the brain of the offspring, at both fetal and adult stages. I found that immune activation resulted in increased levels of IL-6 protein in fetal brain, working memory deficits in the adult offspring, and subtle changes in H3K4me3 levels in fetal and adult brain. Taken together, these findings demonstrate that an environmental risk factor for schizophrenia and autism—namely, inflammation—is capable of inducing robust and widespread histone modifications in a model of the central nervous system and smaller changes in vivo. This suggests that prenatal exposure to inflammation in human populations may lead to increased susceptibility for neuropsychiatric disorders, in part, by altering chromatin modifications in developing brain. v TABLE OF CONTENTS Approval Page............................................................................................ ii Abstract......................................................................................................iii Table of Contents....................................................................................... v List of Figures............................................................................................vii Copyright................................................................................................... ix Chapter 1: Introduction...............................................................................1 Schizophrenia and Autism: An Overview.........................................1 Epigenetics......................................................................................3 Epigenetics and Neuropsychiatric Disease .....................................4 Environment and Epigenetics..........................................................5 Maternal Infection, Schizophrenia, and Autism ...............................8 Immune Dysregulation in Schizophrenia and Autism ....................10 Inflammation and Epigenetics .......................................................13 Chapter 2: Interleukin-6 Alters Histone H3 Lysine 4 Trimethylation in Rat Forebrain Culture: Implications for Neuropsychiatric Disease..................15 Introduction....................................................................................16 Materials and Methods ..................................................................20 Results ..........................................................................................33 Discussion.....................................................................................43 Chapter II Figures..........................................................................51 vi Chapter 3: Maternal Immune Activation Induces Subtle Alterations in Histone H3 Lysine 4 Trimethylation in Fetal and Adult Mouse Brain.....................66 Introduction....................................................................................67 Materials and Methods ..................................................................70 Results ..........................................................................................74 Discussion.....................................................................................83 Chapter III Figures.........................................................................88 Chapter 4: General Discussion ..............................................................103 Appendix 1: A Simple Method for Improving the Specificity of Anti-Methyl Histone Antibodies .................................................................................114 Appendix 2: Cingulate White Matter Neurons in Schizophrenia and Bipolar Disorder .................................................................................................125 Appendix 3: DNA Methylation Changes in Schizophrenia and Bipolar Disorder .................................................................................................161 Appendix 4: DNA methylation in the human cerebral cortex is dynamically regulated throughout the life span and involves differentiated neurons .170 References.............................................................................................199 vii LIST OF FIGURES Figure 2-1: Signaling pathways activated by IL-6 binding to IL-6R................. 17 Figure 2-2: Gfap mRNA and protein demonstrate a dose-dependent upregulation in rat forebrain culture following IL-6 and IL-6R treatment........