An imprinted transcript, antisense to Nesp, adds complexity to the cluster of imprinted genes at the mouse Gnas locus.
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 alpha-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.
Wroe
S F
SF
Mammalian Genetics Unit, Medical Research Council, Harwell, Didcot, Oxfordshire, OX11 0RD, United Kingdom.
Kelsey
G
G
Skinner
J A
JA
Bodle
D
D
Ball
S T
ST
Beechey
C V
CV
Peters
J
J
Williamson
C M
CM
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002864:Chromogranins; D004247:DNA; D019205:GTP-Binding Protein alpha Subunits, Gs; D019204:GTP-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D018392:Genomic Imprinting; D020962:Heterotrimeric GTP-Binding Proteins; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016372:RNA, Antisense / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
D002864:Chromogranins; D009419:Nerve Tissue Proteins; D016372:RNA, Antisense; D012333:RNA, Messenger; D004247:DNA; C406732:GNAS protein, human; D019204:GTP-Binding Proteins; C498642:Gnas protein, mouse; D019205:GTP-Binding Protein alpha Subunits, Gs; D020962:Heterotrimeric GTP-Binding Proteins