A subset of genes in mammals are subject to genomic imprinting. The mouse H19 
gene, for example, is active only when maternally inherited and the neighboring 
Igf2 gene is paternally expressed. This imprinted expression pattern is 
regulated by the imprinting control region (ICR) upstream of the H19 gene. A 
maternally inherited H19 ICR inhibits Igf2 gene activation by the downstream 
enhancer due to its insulator function while it suppresses H19 gene 
transcription by promoter DNA methylation when paternally inherited. These 
parent-of-origin specific functions depend on the allele-specific methylation of 
the ICR DNA, which is established during gametogenesis. Therefore, the ICR may 
also function as a landmark for epigenetic modifications. To examine whether the 
ICR confers these activities autonomously, we introduced a 2.9-kbp 
ICR-containing DNA fragment into a human beta-globin yeast artificial chromosome 
at the 3' end of the locus control region and established transgenic mouse 
lines. Expression of all of the beta-like globin genes was higher when the 
transgene was paternally inherited. In accord with this result, transgenic ICR 
DNA from nucleated erythrocytes was more heavily methylated when paternally 
transmitted. Chromatin immunoprecipitation assays confirmed that CCCTC binding 
factor is preferentially recruited to the maternal transgenic ICR in vivo. 
Surprisingly however, the parent-of-origin specific methylation pattern was not 
observed in germ cell DNA in testis, demonstrating that methylation was 
established after fertilization. Thus, the ICR autonomously recapitulated 
imprinting within the normally nonimprinted transgenic beta-globin gene locus, 
but the temporal establishment of imprinting methylation differs from that at 
the endogenous Igf2/H19 locus.