GSBS Dissertations and Theses

Approval Date

2-14-2013

Document Type

Doctoral Dissertation

Academic Program

Interdisciplinary Graduate Program

Department

Psychiatry

First Thesis Advisor

Schahram Akbarian, PhD

Keywords

Chromatin, N-Methyl-D-Aspartate Receptors, Glutamate Decarboxylase, Brain, Transcription Initiation Site, Transcriptional Regulatory Elements, Schizophrenia

Subjects

Dissertations, UMMS; Chromatin; Receptors, N-Methyl-D-Aspartate; Glutamate Decarboxylase; Brain; Transcription Initiation Site; Regulatory Elements, Transcriptional; Schizophrenia

Abstract

Little is known about higher order chromatin structures in the human brain and their function in transcription regulation. We employed chromosome conformation capture (3C) to analyze chromatin architecture within 700 Kb surrounding the transcription start site (TSS) of the NMDA receptor and schizophrenia susceptibility gene, GRIN2B, in human and mouse cerebral cortex. Remarkably, both species showed a higher interaction between the TSS and an intronic sequence, enriched for (KRAB) Krueppel associated Box domain binding sites and selectively targeted by the (H3K9) histone 3 lysine 9 specific methyltransferase ESET/SETDB1. Transgenic mice brain cortical nuclei over-expressing Setdb1 showed increased heterochromatin-protein 1 signal at the interacting regions coupled with decreased Grin2b expression. 3C further revealed three long distant chromatin loop interactions enriched with functional enhancer specific (H3K27Ac) histone 3 lysine 27 acetylation signal in GRIN2B expressing tissue (human cortical nuclei and Human Embryonic Kidney - HEK cells). Doxycycline-induced SETDB1 over-expression decreased 2 out of 3 loop interaction frequencies suggesting a possible SETDB1-mediated transcription repression. We also report a specific looping interaction between a region 50Kb upstream of the (GAD1) Glutamic Acid Decarboxylase – 1 gene TSS and the GAD1 TSS in human brain nuclei. GAD1 catalyzes the rate limiting step in (GABA) gamma amino-butyric acid synthesis and is quintessential for inhibitory signaling in the human brain. Clinical studies in schizophrenia brain samples reveal a decreased looping interaction frequency in correspondence with a decrease in gene expression. Our findings provide evidence for the existence of transcription relevant higher order chromatin structures in human brain.

Comments

Title on signature page: Regulation of Higher Order Chromatin at GRIN2B and GAD1 Gene Loci in Human and Mouse Brain.

DOI

10.13028/M2Q60Q

Rights and Permissions

Copyright is held by the author, with all rights reserved.

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