An Imprinted Transcript, Antisense to Nesp, Adds Complexity to the Cluster of Imprinted Genes at the Mouse Gnas Locus

• Published in: Proceedings of the National Academy of Sciences - PNAS 2000-03, Vol.97 (7), p.3342-3346
• Main Authors: Wroe, Stephanie F., Kelsey, Gavin, Skinner, Judith A., Bodle, Dorothy, Ball, Simon T., Beechey, Colin V., Peters, Josephine, Williamson, Christine M.
• Format: Article
• Language: English
• Subjects: Alleles; Animals; Base Sequence; Biological Sciences; Blotting, Northern; Chromogranins; chromosome 2; Complementary DNA; DNA; Exons; Gene Expression Regulation; Genes; Genetics; Genomic Imprinting; Genomics; Gnas gene; Gnasxl gene; GTP-Binding Protein alpha Subunits, Gs; GTP-Binding Proteins - genetics; Heterotrimeric GTP-Binding Proteins; Humans; Introns; Mice; Molecular Sequence Data; Multigene Family; Nerve Tissue Proteins - genetics; Nesp gene; Nucleotides; Polymerase chain reaction; Proteins; Reverse transcriptase polymerase chain reaction; RNA; RNA, Antisense - genetics; RNA, Messenger - genetics; Rodents; Sequence Homology, Nucleic Acid
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.050015397

The Gnas locus in distal mouse chromosome (Chr) 2 is emerging as a complex genomic region. It contains three imprinted genes in the order Nesp-Gnasxl-Gnas. Gnas encodes a G protein α -subunit, and Nesp and Gnasxl encode proteins of unknown function expressed in neuroendocrine tissue. Together, these genes form a single transcription unit because transcripts of Nesp and Gnasxl are alternatively spliced onto exon 2 of Gnas. Nesp and Gnasxl are expressed from opposite parental alleles, with Nesp encoding a maternal-specific transcript and Gnasxl encoding a paternal-specific transcript. We now identify a further imprinted transcript in this cluster. Reverse transcription-PCR analysis of Nesp expression in 15.5-days-postcoitum embryos carrying only maternal or paternal copies of distal Chr 2 revealed an isoform that is exclusively paternally, rather than maternally, expressed. Strand-specific reverse transcription-PCR showed that this form is an antisense transcript. The existence of a paternally expressed antisense transcript was confirmed by Northern blot analysis. The sequence is contiguous with genomic sequence downstream of Nesp and encompasses Nesp exons 1 and 2 and an intervening intron. We propose that Nespas is an additional control element in the imprinting region of mouse distal Chr 2; it adds further complexity to the Gnas-imprinted gene cluster.