Action of Mouse Gene Supports Epigenetic Theory

Researchers working with mice have found that the embryonic ectoderm development (Eed) gene is a member of a class of genes that regulates parent-of-origin expression at imprinted loci, a basis for the epigenetic theory of heredity. This finding was published March 10, 2003, in the online edition of Nature Genetics.

Epigenetics refers to modifications in gene expression that are controlled by heritable but potentially reversible changes in DNA methylation and/or chromatin structure. DNA methylation is a post-replication process by which cytosine residues are methylated, forming gene-specific methylation patterns. Housekeeping genes possess promoter regions that are unmethylated in all cell types, whereas tissue-specific genes are methylated in all tissues except the tissue where the gene is expressed. These methylation patterns correlate with gene expression.


In the current study, investigators at the University of North Carolina (Chapel Hill, USA) found that the Eed gene was required for the proper epigenetic regulation of a subset of genes that normally show parent of origin expression, known as genome imprinting.

"Basically, Eed forms a complex of proteins and alters those chromosomal proteins that affect the configuration of the chromosome so as to allow or not allow expression. If this gene, Eed, is not functioning properly, the imprint is lost, resulting in incorrect activity of specific genes,” explained senior author Dr. Terry Magnuson, director of the University of North Carolina's Center for Genome Sciences. "These expression changes are heritable and are not related to sequence changes in the gene that is directly affected.”



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