Aberrant Genomic Imprinting in Rhesus Monkey Embryonic Stem Cells

Abstract

Genomic imprinting involves modification of a gene or a chromosomal region that results in the differential expression of parental alleles. Disruption or inappropriate expression of imprinted genes is associated with several clinically significant syndromes and tumorigenesis in humans. Additionally, abnormal imprinting occurs in mouse embryonic stem cells (ESCs) and in clonally derived animals. Imprinted gene expression patterns in primate ESCs are largely unknown, despite the clinical potential of the latter in the cell-based treatment of human disease. Because of the possible implications of abnormal gene expression to cell or tissue replacement therapies involving ESCs, we examined allele specific expression of four imprinted genes in the rhesus macaque. Genomic and complementary DNA from embryos and ESC lines containing useful single nucleotide polymorphisms were subjected to polymerase chain reaction-based amplification and sequence analysis. In blastocysts, NDN expression was variable indicating abnormal or incomplete imprinting whereas IGF2 and SNRPN were expressed exclusively from the paternal allele and H19 from the maternal allele as expected. In ESCs, both NDN and SNRPN were expressed from the paternal allele while IGF2 and H19 showed loss of imprinting and biallelic expression. In differentiated ESC progeny, these expression patterns were maintained. The implications of aberrant imprinted gene expression to ESC differentiation in vitro and on ESCderived cell function in vivo after transplantation are unknown. STEM CELLS 2006;24:595-603

Germline and somatic imprinting in the nonhuman primate highlights species differences in oocyte methylation

“…Consistent with neonatal rhesus tissues and ES cells, IGF2 and H19 are monoallelically expressed in all cynomolgus extraembryonic tissues analyzed (Fujimoto et al 2005(Fujimoto et al , 2006. H19 expression is also consistently monoallelic in all somatic tissues tested, although the corresponding tissue imprinting of IGF2 is somewhat relaxed, particularly in liver and skeletal muscle ( Fig.…”

Gene-specific vulnerability to imprinting variability in human embryonic stem cell lines

“…All of the HUES-lines were derived from frozen, grade 3-4 blastocysts supernumerary from fertility treatments (Cowan et al 2004). Given several recent reports of increased incidence of imprinting errors in in vitro cultured animal embryos (Young et al 2001;Mann et al 2003Mann et al , 2004Fujimoto et al 2006), children conceived through assisted reproduction technologies (DeBaun et al 2003;Maher 2005;Robertson 2005), in superovulated human oocytes (Sato et al 2007), and in the spermatozoa of oligospermic men (Marques et al 2004), more studies on imprinting in the human embryo are now required to evaluate the biorisk for stem cell derivations. Imprinting variability was not restricted to the HUES-lines and thus cannot be attributed to the use of trypsin passaging on mouse embryonic fibroblast feeders that was unique to these lines (Cowan et al 2004).…”

“…However, this phenomenon has been previously observed, for example Large Offspring Syndrome (LOS) induced by in vitro embryo culture or somatic cell nuclear transfer in sheep (Young et al 2001(Young et al , 2003 disrupts the IGF2R gene that is rarely affected in humans or mice (Gicquel et al 2004). The disruption of IGF2, H19, and other 11p15.5/mouse distal chromosome 7 genes that is relatively more common in humans, rhesus monkeys, and mice (Dean et al 1998;Humpherys et al 2001; Mann et al 2003;Ogawa et al 2003;Mann et al 2004;Fujimoto et al 2006) has not been observed in sheep. Since one possibility is the appropriation of different imprinting regulatory mechanisms between genes in the preimplantation embryo, we examined the status of a candidate epigenetic mechanism, CpG methylation.…”

“…Post-fertilization, the sperm and egg epigenomes are actively reprogrammed into a functional embryonic nucleus with major remodeling of chromatin, histone modifications, and DNA methylation (Jaenisch and Bird 2003;Morgan et al 2005). Epigenetic disruption to imprinted genes has been described in the preimplantation embryos of a range of species when assisted reproduction technologies have been applied (Young et al 2001;Mann et al 2003Mann et al , 2004Maher 2005;Fujimoto et al 2006;Sato et al 2007). Thus we have previously reasoned that at least some human embryonic stem cells (hESCs), derived from human embryos cultured in vitro to the blastocyst stage, may also stably inherit imprinting errors from the donor embryo.…”

Dynamic expression patterns of imprinted genes in human embryonic stem cells following prolonged passaging and differentiation

“…cells were documented to be perturbed [11,12]. Research on a small number of imprinted genes showed that hES cells have a more stable imprinting status compared with mouse ES cells [13].…”