DMMC Course: UNRAVELLING CHROMATIN & THE ROLE OF EPIGENETICS IN DISEASE

1620-1640 Tuesday 25 April 2006. UCD Conway Institute Lecture Theatre

Genomic imprinting: a trans-kingdom perspective
Dr Charlie Spillane SFI Investigator, Biochemistry Department & Biosciences Institute, University College Cork, Ireland.

Genomic imprinting is an epigenetic parent-of-origin effect whereby imprinted genes exhibit differential expression levels in the zygote, depending on whether the allele is of maternal or paternal origin. Because imprinted loci are functionally haploid, their disruption can be lethal during early development. Genomic imprinting has only been observed in mammals and in angiosperms (higher plants). Imprinting in mammalian ancestors first arose in the late Jurassic/early Cretaceous period (approximately 150 million years ago) following the divergence of prototherian from therian mammals. When imprinting first arose in plants is less clear, although the identification of imprinted genes in both monocots (maize) and dicots (Arabidopsis) suggests that imprinting may have arisen in flowering plants at least 145-200 Mya. While over 70 imprinted genes with effects on mammalian development are known, less is known of the nature and role of imprinted genes in plants. Most imprinted genes that have been identified in mammals have regulatory roles in many aspects of human development including fetal and placental growth, cell proliferation, and human behavior. Alteration of normal imprinting patterns is increasingly implicated in a growing number of human genetic diseases, including carcinogenesis and behavioral disorders. The evolutionary conservation of genomic imprinting across the animal and plant kingdoms implies a functional importance for the phenomenon and suggests that studies of genomic imprinting in plants may also provide useful insights into mammalian systems. Our group is conducting research on epigenetic regulation of reproduction and seed development in sexual plants, using Arabidopsis thaliana as a model organism.