The reduced expression of endogenous duplications (REED) in the maize R gene family is mediated by DNA methylation.

Important note: Information in this article was accurate in 1996. The state of the art may have changed since the publication date.

The reduced expression of endogenous duplications (REED) in the maize R gene family is mediated by DNA methylation.

EMBO J. 1995 Nov 1;14(21):5318-28. Unique Identifier : AIDSLINE MED/96080167
Ronchi A; Petroni K; Tonelli C; Dipartimento di Genetica e di Biologia dei microrganismi, Milano,; Italy.

Abstract: The duplicated R and Sn genes regulate the maize anthocyanin biosynthetic pathway and encode tissue-specific products that are homologous to helix-loop-helix transcriptional activators. As a consequence of their coupling in the genome, Sn is partially silenced. Genomic restriction analysis failed to reveal gross structural DNA alterations between the strong original phenotype and the weak derivatives. However, the differences in pigmentation were inversely correlated with differences in the methylation of the Sn promoter. Accordingly, treatment with 5-azacytidine (AZA), a demethylating agent, restored a strong pigmentation pattern that was transmitted to the progeny and that was correlated with differential expression of the Sn transcript. Genomic sequencing confirmed that methylation of the Sn promoter was more apparent in the less pigmented seedlings and was greatly reduced in the AZA revertants. In addition, some methylcytosines were located in non-symmetrical C sequences. These findings provide an insight into Sn and R interaction, a process that we have termed Reduced Expression of Endogenous Duplications (REED). We propose that increasing the copy number of regulatory genes by endogenous duplication leads to such epigenetic mechanisms of silencing. Further understanding of the REED process may have broader implications for gene regulation and may identify new levels of regulation within eukaryotic genomes.

Keywords: Anthocyanins/BIOSYNTHESIS/*GENETICS Base Sequence Corn/*GENETICS/METABOLISM DNA, Plant/*METABOLISM Gene Expression Regulation, Plant Gene Products, vpr/*GENETICS/METABOLISM Genes, Plant Methylation Molecular Sequence Data Plant Proteins/*GENETICS/METABOLISM Support, Non-U.S. Gov't Transcription Factors/*GENETICS/METABOLISM JOURNAL ARTICLE
960330
M9630720

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