Lecture ii fertility preservation in the male : a new clinical paradigm

Imprinted genes are expressed from a single parental allele and most reside in clusters that are located throughout the mammalian genome. The clusters typically contain an imprinting control region (ICR), which harbors allele-specific methylation and governs the imprinting of the entire domain. Although most imprinted clusters use long non-coding RNAs to regulate imprinted gene expression, a few are regulated by CTCF and allele-specific insulator function. One such cluster harbors the H19 and Igf2 imprinted genes, and is controlled by an ICR that contains multiple CTCF binding sites. Gain of maternal methylation and loss of paternal hypermethylation of the H19/IGF2 ICR are associated with the human growth disorders BeckwithWiedemann Syndrome and Silver-Russell Syndrome, respectively. Using gene targeting and genome editing, we have generated ES cells, iPS cell lines and mice to study the mechanisms of imprinting for these imprinted loci and to model the epigenetic mutations in human syndromes. We have also developed SNV-FISH to study the dynamics of allele-specific gene expression at the single cell level in cell lines and tissues with loss of imprinting. We have additionally studied imprinting in animal models of Assisted Reproductive Technologies (ART) and endocrine disrupting chemical exposures (EDCs). Both ART and EDCs are associated with increased loss of imprinting of various genes and with DNA methylation aberrations. The effects are especially pronounced in placenta, where regulation of multiple genes and DNA methylation of repetitive elements are perturbed, and where morphological changes are evident.