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Title:Oct4 and Sox2 regulate methylation at the Igf2/H19 imprinting control region
Author(s):Zimmerman, David
Director of Research:Schoenherr, Christopher J.
Doctoral Committee Chair(s):Belmont, Andrew S.
Doctoral Committee Member(s):Schoenherr, Christopher J.; Chen, Jie; Freeman, Brian C.; Hofmann, Marie-Claude
Department / Program:Cell & Developmental Biology
Discipline:Cell and Developmental Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Gene Imprint
DNA Demethylation
Germ Cell
differentially methylated region (DMR)
imprinting control region (ICR)
Deoxyribonucleic acid (DNA)
Abstract:Mono-allelic expression of H19 and Igf2 depends on parental-specific methylation of an imprinting control region (ICR). Although CTCF sites maintain the absence of DNA methylation on maternal ICRs after fertilization, some Beckwith-Wiedemann patients showed maternal ICR methylation that correlated with mutations in one of the pair of octamer binding sites within the ICR. Using a tissue culture system, we found that both octamers were required for transgene hypomethylation in F9 cells and that Oct4 was present at the endogenous ICR. In addition, each of the octamers is flanked by a sequence that allowed cooperative binding of Oct4 and Sox2 in vitro. To determine at which developmental stage the octamers regulate ICR methylation, we created a knock-in mouse with mutations in the ICR that eliminate Oct4 binding. Maternal transmission of this mutant allele resulted in partial methylation of the maternal ICR in somatic tissues but had little effect on imprinted expression of H19 and Igf2. Although a subset of oocytes showed partial methylation of the mutant ICR, maternally inherited mutant alleles were unmethylated in blastocysts, indicating that the methylation acquired during oogenesis was not a stable imprint. Absence of mutant ICR methylation in female primordial germ cells regardless of parental origin demonstrated that the octamers are not required for imprint erasure but protect the ICR from de novo methylation during oogenesis. These findings provide the first direct evidence that octamers are required for hypomethylation of an endogenous ICR.
Issue Date:2012-06-27
Rights Information:© 2012 David Lee Zimmerman
Date Available in IDEALS:2012-06-27
Date Deposited:2012-05

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