The novel gene, gamma 2-COP (COPG2), in the 7q32 imprinted domain escapes genomic imprinting

The gene MEST (or PEG1) on chromosome 7q32 is paternally expressed in human fetal tissues as a result of genomic imprinting. Since some imprinted gene s are clustered, we speculated that an imprinted gene cluster might exist a t 7q32. We have sought to isolate additional human genes close to MEST and to characterize their allelic expression patterns. Here, we report the bial lelic expression of the gene, gamma 2-COP (coatomer protein complex, subuni t gamma 2, HUGO-approved symbol COPG2), and monoallelic expression of the t ranscript, CIT1, which is located in intron 20 of gamma 2-COP. Recently, ga mma 2-COP was reported to be a novel imprinted gene that overlaps the 3'-un translated region (3'-UTR) of MEST in a tail-to-tail orientation. However, our results revealed biallelic expression in all fetal tissues and adult bl ood lymphocytes. On the other hand, CIT1 was an antisense transcript of gam ma 2-COP intron 20 and was expressed from the paternal allele in all fetal tissues examined. Adult blood lymphocytes showed biallelic expression. We i dentified additional MEST 3'-UTR sequence, which overlaps the last four exo ns and introns of gamma 2-COP. This additional MEST 3'-UTR may complicate a nalysis of gamma 2-COP imprinting. Our data indicate that the region contai ning MEST at 7q32 is an imprinted domain, but gamma 2-COP adjacent to MEST escapes genomic imprinting. (C) 2000 Academic Press.