title: Expression and methylation status of imprinted genes in placentas of deceased and live cloned transgenic calves.
abstract: Placental deficiencies are linked with developmental abnormalities in cattle produced by somatic cell nuclear transfer (SCNT). To investigate whether the aberrant expression of imprinted genes in placenta was responsible for fetal overgrowth and placental hypertrophy, quantitative expression analysis of six imprinted genes (H19, XIST, IGF2R, SNRPN, PEG3, and IGF2) was conducted in placentas of: 1) deceased (died during perinatal period) transgenic calves (D group, n = 4); 2) live transgenic calves (L group, n = 15); and 3) conventionally produced (control) female calves (N group, n = 4). In this study, XIST, PEG3 and IGF2 were significantly over-expressed in the D group, whereas expression of H19 and IGF2R was significantly reduced in the D group compared to controls. The DNA methylation patterns in the differentially methylated region (DMR) from H19, XIST, and IGF2R were compared using Bisulfite Sequencing PCR (BSP) and Combined Bisulfite Restriction Analysis (COBRA). In the D group, H19 DMR was significantly hypermethylated, but XIST DMR and IGF2R ICR were significantly hypomethylated compared to controls. In contrast, there were no noticeable differences in the expression and DNA methylation status of imprinted genes (except DNA methylation level of XIST DMR) in the L group compared to controls. In conclusion, altered DNA methylation levels in the DMRs of imprinted genes in placentas of deceased transgenic calves, presumably due to aberrant epigenetic nuclear reprogramming during SCNT, may have been associated with abnormal expression of these genes; perhaps this caused developmental insufficiencies and ultimately death in cloned transgenic calves.
authors.affiliation: College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Reproductive Physiology & Embryo Technology, Ministry of Agriculture, Yangling, Shaanxi, PR China. sujianmin@gmail.com
authors.forename: Jian-min
authors.initials: JM
authors.lastname: Su
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.forename: Yong-sheng
authors.initials: YS
authors.lastname: Wang
authors.forename: Yan-yan
authors.initials: YY
authors.lastname: Li
authors.forename: Xian-rong
authors.initials: XR
authors.lastname: Xiong
authors.forename: Li-jun
authors.initials: LJ
authors.lastname: Wang
authors.forename: Ze-kun
authors.initials: ZK
authors.lastname: Guo
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002417:Cattle / Q000235:genetics*; D019976:Cloning, Organism / Q000662:veterinary; D019175:DNA Methylation; D005260:Female; D005313:Fetal Death / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D050437:Genes, Developmental / Q000235:genetics*; D018392:Genomic Imprinting / Q000502:physiology*; D050498:Live Birth / Q000235:genetics* / Q000662:veterinary; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism
chemical_list: C094335:H19 long non-coding RNA; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C077885:XIST non-coding RNA