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Gene Expression Patterns

Oxygen-induced alterations in the expression of chromatin modifying enzymes and the transcriptional regulation of imprinted genes

William M. Skiles, Avery Kester, Jane H. Pryor, Mark E. Westhusin, Michael C. Golding, Charles R. Long

Department of Veterinary Physiology & Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843-4466, USA.


Embryo culture and assisted reproductive technologies have been associated with a disproportionately high number of epigenetic abnormalities in the resulting offspring. However, the mechanisms by which these techniques influence the epigenome remain poorly defined. In this study, we evaluated the capacity of oxygen concentration to influence the transcriptional control of a selection of key enzymes regulating chromatin structure. In mouse embryonic stem cells, oxygen concentrations modulated the transcriptional regulation of the TET family of enzymes, as well as the de novomethyltransferase Dnmt3a. These transcriptional changes were associated with alterations in the control of multiple imprinted genes, including H19Igf2Igf2r, and Peg3. Similarly, exposure of in vitro produced bovine embryos to atmospheric oxygen concentrations was associated with disruptions in the transcriptional regulation of TET1TET3 and DNMT3a, along with the DNA methyltransferase co-factor HELLS. In addition, exposure to high oxygen was associated with alterations in the abundance of transcripts encoding members of the Polycomb repressor complex (EED and EZH2), the histone methyltransferase SETDB1 and multiple histone demethylases (KDM1AKDM4B and KDM4C). These disruptions were accompanied by a reduction in embryo viability and suppression of the pluripotency genes NANOG and SOX2. These experiments demonstrate that oxygen has the capacity to modulate the transcriptional control of chromatin modifying genes involved in the establishment and maintenance of both pluripotency and genomic imprinting.

Keywords: Oxidative stress; Assisted reproductive technologies; Genomic imprinting; Histone demethylase; TET; DNMT; DNA methylation; Epigenetics; Developmental programming.

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