title: Extra-embryonic-specific imprinted expression is restricted to defined lineages in the post-implantation embryo.
abstract: A subset of imprinted genes in the mouse have been reported to show imprinted expression that is restricted to the placenta, a short-lived extra-embryonic organ. Notably, these so-called "placental-specific" imprinted genes are expressed from both parental alleles in embryo and adult tissues. The placenta is an embryonic-derived organ that is closely associated with maternal tissue, and as a consequence, maternal contamination can be mistaken for maternal-specific imprinted expression. The complexity of the placenta, which arises from multiple embryonic lineages, poses additional problems in accurately assessing allele-specific repressive epigenetic modifications in genes that also show lineage-specific silencing in this organ. These problems require that extra evidence be obtained to support the imprinted status of genes whose imprinted expression is restricted to the placenta. We show here that the extra-embryonic visceral yolk sac (VYS), a nutritive membrane surrounding the developing embryo, shows a similar "extra-embryonic-lineage-specific" pattern of imprinted expression. We present an improved enzymatic technique for separating the bilaminar VYS and show that this pattern of imprinted expression is restricted to the endoderm layer. Finally, we show that VYS "extra-embryonic-lineage-specific" imprinted expression is regulated by DNA methylation in a similar manner as shown for genes showing multi-lineage imprinted expression in extra-embryonic, embryonic, and adult tissues. These results show that the VYS is an improved model for studying the epigenetic mechanisms regulating extra-embryonic-lineage-specific imprinted expression.
authors.affiliation: CeMM, Research Center for Molecular Medicine of the Austrian Academy of Science, Lazarettgasse 14, AKH-BT 25.3, 1090 Vienna, Austria.
authors.forename: Quanah J
authors.initials: QJ
authors.lastname: Hudson
authors.forename: Christine I M
authors.initials: CI
authors.lastname: Seidl
authors.forename: Tomasz M
authors.initials: TM
authors.lastname: Kulinski
authors.forename: Ru
authors.initials: R
authors.lastname: Huang
authors.forename: Katarzyna E
authors.initials: KE
authors.lastname: Warczok
authors.forename: Romana
authors.initials: R
authors.lastname: Bittner
authors.forename: Marisa S
authors.initials: MS
authors.lastname: Bartolomei
authors.forename: Denise P
authors.initials: DP
authors.lastname: Barlow
mesh_terms: D000818:Animals; D001483:Base Sequence; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000172:deficiency / Q000235:genetics; D019175:DNA Methylation; D017931:DNA Primers / Q000235:genetics; D004707:Endoderm / Q000196:embryology / Q000378:metabolism; D044127:Epigenesis, Genetic; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018392:Genomic Imprinting; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D018345:Mice, Knockout; D008957:Models, Genetic; D005810:Multigene Family; D027701:Organic Cation Transport Proteins / Q000235:genetics; D000075102:Organic Cation Transporter 2; D010920:Placenta / Q000196:embryology / Q000378:metabolism; D011247:Pregnancy; D015017:Yolk Sac / Q000196:embryology* / Q000378:metabolism*; D000099254:Organic Cation Transporter 3
chemical_list: D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D017931:DNA Primers; D027701:Organic Cation Transport Proteins; D000075102:Organic Cation Transporter 2; D000099254:Organic Cation Transporter 3; C491012:Slc22a2 protein, mouse