106 GENOMIC IMPRINTING OF IGF2R IN TISSUES OF BOVINE FETUSES GENERATED BY ARTIFICIAL INSEMINATION OR IN VITRO FERTILIZATION
S. Hiendleder A , D. Bebbere B , S. Bauersachs A , M. Stojkovic A , H. Wenigerkind C , H.-D. Reichenbach D , S. Ledda B and E. Wolf AA Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University Munich, 81377 Munich, Germany
B Department of Animal Biology, University of Sassari, Sassari, Italy
C Bavarian Research Center for Biology of Reproduction (BFZF), 85764 Obserschleissheim, Germany
D Institute for Animal Breeding, Bavarian State Research Center for Agriculture (LfL), 85586 Grub, Germany. Email: S.Hiendleder@gen.vetmed.uni-muenchen.de
Reproduction, Fertility and Development 17(2) 204-204 https://doi.org/10.1071/RDv17n2Ab106
Submitted: 1 August 2004 Accepted: 1 October 2004 Published: 1 January 2005
Abstract
The insulin-like growth factor 2 receptor gene (IGF2R) is involved in fetal growth regulation. A study in sheep associated fetal overgrowth after in vitro embryo culture with abnormal DNA methylation and expression of IGF2R (Young et al. 2001 Nat. Genet. 27, 153–154). This suggested that abnormal IGF2R imprinting is a major cause of fetal overgrowth. To test this hypothesis in bovine fetuses, we developed a microsatellite marker for IGF2R from cDNA sequence data and screened 45 Day-80 fetuses generated in vivo, by artificial insemination (AI), or in vitro, by in vitro fertilization (IVF) procedures, for parent-of-origin-specific gene expression. A total of 17 fetuses were heterozygous, but available parental DNA samples showed that only 12 (8 AI, 4 IVF) allowed unambiguous discrimination of parental alleles. Parent-of-origin-specific allelic expression patterns indicated that bovine IGF2R was expressed predominantly from the maternal allele and thus imprinted in fetal heart, kidney, liver, lung, muscle, and cotyledon tissue. However, the relative amount of expression from the paternal allele was tissue-specific and ranged from 6.4 ± 0.8% in skeletal muscle up to 27.4 ± 0.9% in cotyledon (SPSS or 11.5, ANOVA, P < 0.001). Tissues that originated from the same germ layer showed similar allelic expression ratios whereas significantly different expression ratios (P < 0.05) were observed between tissues originating from different germ layers. Contrary to expectations from sheep data, there was no evidence for gross abnormalities in IGF2R imprinting in tissues from overgrown (n = 2) or normal sized (n = 2) IVF fetuses. However, relative paternal expression levels in several tissues showed significant relationships (P < 0.05–0.001) with growth parameters and pointed to subtle changes in paternal IGF2R expression in overgrown IVF fetuses.
We thank W. Scholz and M. Weppert for excellent technical assistance.
