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Silencing and transcriptional properties of the imprinted Airn ncRNA are independent of the endogenous promoter
Author(s) -
Stricker Stefan H,
Steenpass Laura,
Pauler Florian M,
Santoro Federica,
Latos Paulina A,
Huang Ru,
Koerner Martha V,
Sloane Mathew A,
Warczok Katarzyna E,
Barlow Denise P
Publication year - 2008
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2008.239
Subject(s) - library science , biological sciences , research center , art history , biology , political science , art , law , computational biology , computer science
The Airn macro ncRNA is the master regulator of imprinted expression in the Igf2r imprinted gene cluster where it silences three flanking genes in cis . Airn transcription shows unusual features normally viewed as promoter specific, such as impaired post‐transcriptional processing and a macro size. The Airn transcript is 108 kb long, predominantly unspliced and nuclear localized, with only a minority being variably spliced and exported. Here, we show by deletion of the Airn ncRNA promoter and replacement with a constitutive strong or weak promoter that splicing suppression and termination, as well as silencing activity, are maintained by strong Airn expression from an exogenous promoter. This indicates that all functional regions are located within the Airn transcript. DNA methylation of the maternal imprint control element (ICE) restricts Airn expression to the paternal allele and we also show that a strong active promoter is required to maintain the unmethylated state of the paternal ICE. Thus, Airn expression not only induces silencing of flanking mRNA genes but also protects the paternal copy of the ICE from de novo methylation.