In order to assess if there are any differences in gene expression between normal and abnormal karyotype hESC lines, we examined maternal expressed imprinted geneH19, paternal expressed imprinted gene IGF2 and SNRPN and conditional gene GNAS as disrupted expression of these genes is associated with human genetic diseases, such as PWS and AS.
Figure 1 figure supplement 1 shows allele-specific expression data for paternally expressed imprinted genes (PEGs).
For quantitative analysis of maternally and paternally expressed imprinted genes, Xist expression, and telomere length measurements, statistical analysis with SDS v. 1.1 software (Applied Biosystems) was used.
Amongst a group of differentially expressed imprinted genes, two maternal imprinted genes that suppress growth induced via the IGF signalling pathway, Grb10 and Igf2r, were under-represented in QSi5 mice.
Conversely, maternal biases to imprinted gene expression, as from reductions in paternally expressed imprinted gene products, should lead to reduced bonding and attachment, less sucking, and slower growth.
The extent of overlap between our cDNA-AFLP screen for maternally expressed imprinted genes, and other screens for imprinted and endosperm-expressed genes is discussed.
However we do not exclude that other epigenetic controls such as histone methylation by Polycomb group complexes [26] [28] are responsible for an opposite action of the expression between paternally and maternally expressed imprinted genes.
However, expression levels of known maternally expressed imprinted genes in PESCs were similar to control ESCs suggesting that parthenotes may not be suitable for screening of novel maternally imprinted genes.
Pleckstrin homology-like domain family A member 2 (PHLDA2) is a maternally expressed imprinted gene whose elevated expression has been linked to fetal growth restriction in a number of human studies.
Interestingly, in the three pairs, Peg13-1810044A24Rik, Nnat-Blcap and Zrsr1- Commd1, the first gene is a paternally expressed imprinted gene with 100% monoallelic expression, whereas the second gene is maternally expressed partially imprinted gene (Figure 4).
