Genomic imprinting affects a subset of genes in mammals, such that they are expressed in a monoallelic, parent-of-origin-specific manner. These genes are regulated by imprinting control regions (ICRs), cis-regulatory elements that exhibit allele-specific differential DNA methylation. Although genomic imprinting is conserved in mammals, ICRs are genetically divergent across species. This raises the fundamental question of whether the ICR plays a species-specific role in regulating imprinting at a given locus. We addressed this question at the H19/insulin-like growth factor 2 (Igf2) imprinted locus, the misregulation of which is associated with the human imprinting disorders Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS). We generated a knock-in mouse in which the endogenous H19/Igf2 ICR (mIC1) is replaced by the orthologous human ICR (hIC1) sequence, designated H19 hIC1 . We show that hIC1 can functionally replace mIC1 on the maternal allele. In contrast, paternally transmitted hIC1 leads to growth restriction, abnormal hIC1 methylation, and loss of H19 and Igf2 imprinted expression. Imprint establishment at hIC1 is impaired in the male germ line, which is associated with an abnormal composition of histone posttranslational modifications compared with mIC1. Overall, this study reveals evolutionarily divergent paternal imprinting at IC1 between mice and humans. The conserved maternal imprinting mechanism and function at IC1 demonstrates the possibility of modeling maternal transmission of hIC1 mutations associated with BWS in mice. In addition, we propose that further analyses in the paternal knockin H19 +/hIC1 mice will elucidate the molecular mechanisms that may underlie SRS.G enomic imprinting is a conserved, epigenetic process in mammals that regulates the expression of a small number of genes in a monoallelic, parent-of-origin-specific manner. Typically clustered within domains, the parental-specific expression of imprinted genes is controlled by a cis-regulatory element, the imprinting control region (ICR). During gametogenesis, ICRs acquire differential DNA methylation patterns according to the sex of the germ cells. This DNA methylation is maintained in somatic cells after fertilization but is erased in primordial germ cells, allowing the establishment of sex-specific imprints in mature gametes. The proper establishment, maintenance, and erasure of imprints are crucial for the correct expression of imprinted genes. Misregulation of imprinted genes is associated with human imprinting disorders, including Beckwith-Wiedemann syndrome (BWS), an overgrowth disorder, and Silver-Russell syndrome (SRS), an undergrowth disorder (1-3).Mouse models have been valuable to the study of imprinting at the H19/insulin-like growth factor 2 (Igf2) locus, serving as a proxy for the orthologous human locus. On distal mouse chromosome 7, reciprocal imprinting of the paternally expressed fetal growth factor gene, Igf2, and the maternally expressed noncoding RNA, H19, is regulated by the ICR located between H...

19A highly aggressive subset of pancreatic ductal adenocarcinomas undergo trans-differentiation into 20 the squamous lineage during disease progression. Here, we investigated whether squamous trans-21 differentiation of human and mouse pancreatic cancer cells can influence the phenotype of non-22

Lineage plasticity is a prominent feature of pancreatic ductal adenocarcinoma (PDA) cells, which can occur via deregulation of lineage-specifying transcription factors. Here, we show that the zinc finger protein ZBED2 is aberrantly expressed in PDA and alters tumor cell identity in this disease. Unexpectedly, our epigenomic experiments reveal that ZBED2 is a sequence-specific transcriptional repressor of IFN-stimulated genes, which occurs through antagonism of IFN regulatory factor 1 (IRF1)-mediated transcriptional activation at cooccupied promoter elements. Consequently, ZBED2 attenuates the transcriptional output and growth arrest phenotypes downstream of IFN signaling in multiple PDA cell line models. We also found that ZBED2 is preferentially expressed in the squamous molecular subtype of human PDA, in association with inferior patient survival outcomes. Consistent with this observation, we show that ZBED2 can repress the pancreatic progenitor transcriptional program, enhance motility, and promote invasion in PDA cells. Collectively, our findings suggest that high ZBED2 expression is acquired during PDA progression to suppress the IFN response pathway and to promote lineage plasticity in this disease.

Differential DNA methylation defects of H19/IGF2 are associated with congenital growth disorders characterized by opposite clinical pictures. Due to structural differences between human and mouse, the mechanisms by which mutations of the H19/IGF2 Imprinting Control region (IC1) result in these diseases are undefined. To address this issue, we previously generated a mouse line carrying a humanized IC1 (hIC1) and now replaced the wildtype with a mutant IC1 identified in the overgrowth-associated Beckwith-Wiedemann syndrome. The new humanized mouse line shows pre/post-natal overgrowth on maternal transmission and pre/post-natal undergrowth on paternal transmission of the mutation. The mutant hIC1 acquires abnormal methylation during development causing opposite H19/Igf2 imprinting defects on maternal and paternal chromosomes. Differential and possibly mosaic Igf2 expression and imprinting is associated with asymmetric growth of bilateral organs. Furthermore, tissue-specific imprinting defects result in deficient liver- and placenta-derived Igf2 on paternal transmission and excessive Igf2 in peripheral tissues on maternal transmission, providing a possible molecular explanation for imprinting-associated and phenotypically contrasting growth disorders.

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