Monoallelic expression and methylation of imprinted genes in human and mouse embryonic germ cell lineages.
Imprinting is an epigenetic modification leading to monoallelic expression of some genes, and disrupted imprinting is believed to be a barrier to human stem cell transplantation, based on studies that suggest that epigenetic marks are unstable in mouse embryonic germ (EG) and embryonic stem (ES) cells. However, stem cell imprinting has not previously been examined directly in humans. We found that three imprinted genes, TSSC5, H19, and SNRPN, show monoallelic expression in in vitro differentiated human EG-derived cells, and a fourth gene, IGF2, shows partially relaxed imprinting at a ratio from 4:1 to 5:1, comparable to that found in normal somatic cells. In addition, we found normal methylation of an imprinting control region (ICR) that regulates H19 and IGF2 imprinting, suggesting that imprinting may not be a significant epigenetic barrier to human EG cell transplantation. Finally, we were able to construct an in vitro mouse model of genomic imprinting, by generating EG cells from 8.5-day embryos of an interspecific cross, in which undifferentiated cells show biallelic expression and acquire preferential parental allele expression after differentiation. This model should allow experimental manipulation of epigenetic modifications of cultured EG cells that may not be possible in human stem cell studies.
Onyango
Patrick
P
Institute of Genetic Medicine and Department of Medicine, Johns Hopkins University School of Medicine, 1064 Ross, 720 Rutland Avenue, Baltimore, MD 21205, USA.
Jiang
Shan
S
Uejima
Hiroshi
H
Shamblott
Michael J
MJ
Gearhart
John D
JD
Cui
Hengmi
H
Feinberg
Andrew P
AP
D000483:Alleles; D000818:Animals; D019070:Cell Lineage; D002478:Cells, Cultured; D019175:DNA Methylation; D005260:Female; D020862:GC Rich Sequence; D015870:Gene Expression; D016147:Genes, Tumor Suppressor; D018392:Genomic Imprinting; D005854:Germ Cells; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics
D017411:Ribonucleoproteins, Small Nuclear; D007335:Insulin-Like Growth Factor II