title: Promoter-specific expression and imprint status of marsupial IGF2.
abstract: In mice and humans, IGF2 has multiple promoters to maintain its complex tissue- and developmental stage-specific imprinting and expression. IGF2 is also imprinted in marsupials, but little is known about its promoter region. In this study, three IGF2 transcripts were isolated from placental and liver samples of the tammar wallaby, Macropus eugenii. Each transcript contained a unique 5' untranslated region, orthologous to the non-coding exons derived from promoters P1-P3 in the human and mouse IGF2 locus. The expression of tammar IGF2 was predominantly from the P2 promoter, similar to humans. Expression of IGF2 was higher in pouch young than in the adult and imprinting was highly tissue and developmental-stage specific. Interestingly, while IGF2 was expressed throughout the placenta, imprinting seemed to be restricted to the vascular, trilaminar region. In addition, IGF2 was monoallelically expressed in the adult mammary gland while in the liver it switched from monoalleleic expression in the pouch young to biallelic in the adult. These data suggest a complex mode of IGF2 regulation in marsupials as seen in eutherian mammals. The conservation of the IGF2 promoters suggests they originated before the divergence of marsupials and eutherians, and have been selectively maintained for at least 160 million years.
authors: ARC Centre of Excellence in Kangaroo Genomics, The University of Melbourne, Victoria, Australia.
authors: Jessica M
authors: JM
authors: Stringer
authors: Shunsuke
authors: S
authors: Suzuki
authors: Andrew J
authors: AJ
authors: Pask
authors: Geoff
authors: G
authors: Shaw
authors: Marilyn B
authors: MB
authors: Renfree
mesh_terms: D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D019175:DNA Methylation; D019143:Evolution, Molecular; D005260:Female; D005786:Gene Expression Regulation; D056426:Genetic Loci / Q000235:genetics; D018392:Genomic Imprinting / Q000235:genetics*; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008099:Liver / Q000378:metabolism; D007614:Macropodidae / Q000235:genetics*; D008297:Male; D051379:Mice; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D024363:Transcription Initiation Site
chemical_list: D012333:RNA, Messenger; D007335:Insulin-Like Growth Factor II