Most genes in mammals are expressed equally from the maternally and paternally inherited alleles. However, some genes are parentally imprinted, and are expressed exclusively from a single parent's allele. One consequence of imprinted genes is that a single mutation or deletion, in the expressed allele, will result in the absence of a gene product. These types of mutations are most likely involved in genetic diseases such as Beckwith-Wiedemann Syndrome, Prader-Willi Syndrome and Angelman Syndrome. In contrast, relaxation of the imprinting of two genes, IGF2 and H19, has been associated with gene activation in Wilms' tumor and may be part of a new genetic mechanism involved in the development of cancer. The objective of the studies described in this proposal is to learn how parental identity of imprinted genes is assigned. The studies will employ the H19 gene, which is expressed from the maternally derived allele in mice and humans. The recent demonstration that the inactive allele of H19 is highly methylated suggests that methylation may be involved in the mediation of imprinting. Furthermore, the analysis of H19 transgenes, which recapitulate the imprinting of the endogenous locus, indicates that cis-acting sequences can be tested for the conferral of imprinting using transgenic mice. The experiments designed in this proposal will: (i) determine if allele-specific methylation designates and perpetuates parental identity by first assessing allele-specific methylation in germ cells and the early embryo, and then mutagenizing CpG dinculeotides that remain differentially methylated and testing the altered DNA in transgenic mice; (2) use transgenic mice to identify the cis-acting sequences that cause the H19 gene to be imprinted and subsequently determine if the minimal identified sequences will imprint another mammalian gene; and (3) assess the role of strain-specific trans-acting modifiers in the imprinting of the newly derived transgenic mouse lines. These experiments will eventually allow the identification of trans-acting factors that determine imprinting. An understanding of how the imprinting process normally operates will allow greater understanding of how imprinting is altered in cancers such as Wilms' tumor.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Mammalian Genetics Study Section (MGN)
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University of Pennsylvania
Anatomy/Cell Biology
Schools of Medicine
United States
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Hur, Stella K; Freschi, Andrea; Ideraabdullah, Folami et al. (2016) Humanized H19/Igf2 locus reveals diverged imprinting mechanism between mouse and human and reflects Silver-Russell syndrome phenotypes. Proc Natl Acad Sci U S A 113:10938-43
Ginart, Paul; Kalish, Jennifer M; Jiang, Connie L et al. (2016) Visualizing allele-specific expression in single cells reveals epigenetic mosaicism in an H19 loss-of-imprinting mutant. Genes Dev 30:567-78
Zhong, Cuiqing; Yin, Qi; Xie, Zhenfei et al. (2015) CRISPR-Cas9-Mediated Genetic Screening in Mice with Haploid Embryonic Stem Cells Carrying a Guide RNA Library. Cell Stem Cell 17:221-32
Plasschaert, Robert N; Bartolomei, Marisa S (2015) Tissue-specific regulation and function of Grb10 during growth and neuronal commitment. Proc Natl Acad Sci U S A 112:6841-7
Weaver, Jamie R; Bartolomei, Marisa S (2014) Chromatin regulators of genomic imprinting. Biochim Biophys Acta 1839:169-77
Ideraabdullah, Folami Y; Thorvaldsen, Joanne L; Myers, Jennifer A et al. (2014) Tissue-specific insulator function at H19/Igf2 revealed by deletions at the imprinting control region. Hum Mol Genet 23:6246-59
Venkatraman, Aparna; He, Xi C; Thorvaldsen, Joanne L et al. (2013) Maternal imprinting at the H19-Igf2 locus maintains adult haematopoietic stem cell quiescence. Nature 500:345-9
Abramowitz, Lara K; Bartolomei, Marisa S (2012) Genomic imprinting: recognition and marking of imprinted loci. Curr Opin Genet Dev 22:72-8
Wu, Xin; Goodyear, Shaun M; Abramowitz, Lara K et al. (2012) Fertile offspring derived from mouse spermatogonial stem cells cryopreserved for more than 14 years. Hum Reprod 27:1249-59
Hudson, Quanah J; Seidl, Christine I M; Kulinski, Tomasz M et al. (2011) Extra-embryonic-specific imprinted expression is restricted to defined lineages in the post-implantation embryo. Dev Biol 353:420-31

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