Dataset Information

Mechanisms of genomic imprinting.

ABSTRACT: Imprinted genes represent a curious defiance of normal Mendelian genetics. Mammals inherit two complete sets of chromosomes, one from the mother and one from the father, and most autosomal genes will be expressed from both the maternal and the paternal alleles. Imprinted genes, however, are expressed from only one chromosome, in a parent-of-origin-dependent manner. Because silent and active promoters are present in a single nucleus, the differences in activity cannot be explained by transcription-factor abundance. Thus, transcription of imprinted genes represents a clear situation in which epigenetic mechanisms restrict gene expression and, therefore, offers a model for understanding the role of DNA modifications and chromatin structure in maintaining appropriate patterns of expression. Furthermore, because of their parent-of-origin-restricted expression, phenotypes determined by imprinted genes are susceptible not only to genetic alterations in the genes but also to disruptions in the epigenetic programs controlling regulation. Imprinted genes are often associated with human diseases, including disorders affecting cell growth, development, and behavior.

SUBMITTER: Pfeifer K

PROVIDER: S-EPMC1287882 | biostudies-literature | 2000 Oct

REPOSITORIES: biostudies-literature

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Mechanisms of genomic imprinting.

Pfeifer K K

American journal of human genetics 20000905 4

Imprinted genes represent a curious defiance of normal Mendelian genetics. Mammals inherit two complete sets of chromosomes, one from the mother and one from the father, and most autosomal genes will be expressed from both the maternal and the paternal alleles. Imprinted genes, however, are expressed from only one chromosome, in a parent-of-origin-dependent manner. Because silent and active promoters are present in a single nucleus, the differences in activity cannot be explained by transcriptio ...[more]

PMID: 10986038

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Project description:Imprinted genes are peculiar in that expression of the two copies differs depending on whether the copy was maternally or paternally inherited. The discovery of this striking pattern of gene expression inspired myriad evolutionary theories, the most successful of which identify scenarios that create an asymmetry between the maternally and paternally inherited gene copies that favors silencing of one of the copies. Most notably, imprinting can evolve when gene dosage affects kin interactions (typically involving conflict) or when silencing enhances coadaptation by coordinating traits expressed by interacting kin. Although we have a well-established theory for the former process (the "Kinship Theory"), the coadaptation process has only been explored for the specific case of interactions between mothers and offspring. Here, we fill this critical gap in our understanding by developing a general "Coadaptation Theory" that explains how imprinting can evolve to coordinate interactions between all types of relatives. Using a simple model in which fitness of an individual is determined by an interaction between its own phenotype (and hence genotype) and that of its social partner(s), we find that when the relatedness of interactants differs through their maternally versus paternally inherited gene copies, then selection favors expression of the allele through which relatedness is higher. The predictions of this Coadaptation Theory potentially apply whenever a gene underlies traits that mediate the outcome of conspecific interactions, regardless of their mechanism or the type of organism, and therefore provide a potential explanation for enigmatic patterns of imprinting, including those underlying adult traits. By providing simple testable predictions that often directly contrast with those derived from alternative theories, our model should play an important role in consolidating our understanding of the evolution of imprinting across genes and species, which will ultimately provide crucial insights into imprinted gene function and dysfunction.

Dataset Information

Mechanisms of genomic imprinting.

Publications

Mechanisms of genomic imprinting.

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