Allelic IGF2R repression does not correlate with expression of antisense RNA in human extraembryonic tissues

In the mouse, expression of an antisense Igf2r RNA (Air) is correlated with Igf2r repression on the paternal allele, One of the possible models for Ig f2r repression could be through promoter competition or through the action of the Air RNA, in, e.g., transcriptional interference or repressor binding . These models predict the conservation of AIR RNA in human samples with mo noallelic IGF2R expression and the production of AIR RNA in first-trimester human tissues. However, by strand-specific RT-PCR and by ribonuclease prot ection assay we have not detected any AIR RNA in first-trimester placental tissue samples, not even in samples that downregulate IGF2R expression in a n allele-specific manner. This indicates that in contrast to the mouse, all elic IGF2R repression in the developing human placenta does not correlate w ith AIR expression. (C) 2001 Academic Press.