title: Aberrant expression of imprinted genes in post-implantation rat embryos.
abstract: OBJECTIVE
  Imprinted genes are known regulators of embryo growth. Studies from our laboratory have demonstrated that treatment of adult male rats with tamoxifen increased post-implantation loss at around midgestation. Expression of insulin like growth factor 2 (Igf2), a paternally expressed imprinted gene was down-regulated in the resorbing embryos obtained at embryonic day 13. Hypomethylation of Igf2-H19 imprint control region was observed in the resorbing embryo sires and spermatozoa obtained from tamoxifen-treated rats thereby suggesting that errors in imprint acquisition during spermatogenesis can result in embryo loss. The present study aims at studying the expression of other imprinted genes, besides Igf2 in the embryos sired by tamoxifen-treated males.
  
  
  METHODS
  Gene expression profiles of resorbing versus normal embryos were assessed by microarrays. Real time quantitative RT-PCR for six imprinted genes and four genes involved in cell cycle was done to validate gene expression data. The affected pathways and functions were identified in the resorbing embryos and effect on cell cycle was confirmed by flow cytometry.
  
  
  RESULTS
  Aberrant expression of a number of imprinted genes was observed in the resorbing embryos when compared to the normal embryos at embryonic days 11 and 13. Down-regulation of Notch signaling, Wnt signaling and cell cycle pathway was observed in the resorbing embryos.
  
  
  CONCLUSIONS
  The study suggests that exposure of male germ cells to tamoxifen during adulthood results in aberrant expression of imprinted genes and down-regulation of development associated pathways in the F(1) progeny thereby causing embryo loss.
authors.affiliation: National Institute for Research in Reproductive Health (ICMR), Parel, Mumbai-400012, India.
authors.forename: Neelam A
authors.initials: NA
authors.lastname: Kedia-Mokashi
authors.forename: Raja
authors.initials: R
authors.lastname: Mugasimangalam
authors.forename: Mohammed
authors.initials: M
authors.lastname: Aiyaz
authors.forename: Srabani
authors.initials: S
authors.lastname: Mukherjee
authors.forename: N H
authors.initials: NH
authors.lastname: Balasinor
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000235:genetics; D020964:Embryo Loss / Q000235:genetics*; D004622:Embryo, Mammalian / Q000166:cytology; D047108:Embryonic Development / Q000235:genetics*; D005260:Female; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018392:Genomic Imprinting; D005865:Gestational Age; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D018812:Paternal Exposure; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology*; D013629:Tamoxifen / Q000494:pharmacology*
chemical_list: D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen