An antisense RNA regulates the bidirectional silencing property of the Kcnq1 imprinting control region.
The Kcnq1 imprinting control region (ICR) located in intron 10 of the Kcnq1 gene is unmethylated on the paternal chromosome and methylated on the maternal chromosome and has been implicated in the manifestation of parent-of-origin-specific expression of six neighboring genes. The unmethylated Kcnq1 ICR harbors bidirectional silencer activity and drives expression of an antisense RNA, Kcnq1ot1, which overlaps the Kcnq1 coding region. To elucidate whether the Kcnq1ot1 RNA plays a role in the bidirectional silencing activity of the Kcnq1 ICR, we have characterized factor binding sites by genomic footprinting and tested the functional consequence of various deletions of these binding sites in an episome-based system. Deletion of the elements necessary for Kcnq1ot1 promoter function resulted in the loss of silencing activity. Furthermore, interruption of Kcnq1ot1 RNA production by the insertion of a polyadenylation sequence downstream of the promoter also caused a loss of both silencing activity and methylation spreading. Thus, the antisense RNA plays a key role in the silencing function of the ICR. Double-stranded RNA (dsRNA)-mediated RNA interference is unlikely to be involved, as the ICR is active irrespective of the simultaneous production of dsRNA from the genes it silences.
Thakur
Noopur
N
Department of Development and Genetics, Evolution Biology Centre, Uppsala University, Norbyvägen 18A, S-752 36 Uppsala, Sweden. kanduri.chandrasekhar@ebc.uu.se
Tiwari
Vijay Kumar
VK
Thomassin
Helene
H
Pandey
Radha Raman
RR
Kanduri
Meena
M
Göndör
Anita
A
Grange
Thierry
T
Ohlsson
Rolf
R
Kanduri
Chandrasekhar
C
D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000737:chemistry / Q000235:genetics; D018983:DNA Footprinting; D019175:DNA Methylation; D003850:Deoxyribonuclease I; D005260:Female; D005786:Gene Expression Regulation; D020868:Gene Silencing; D017930:Genes, Reporter; D018392:Genomic Imprinting; D006801:Humans; D007438:Introns; D051656:KCNQ Potassium Channels; D051657:KCNQ1 Potassium Channel; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D015221:Potassium Channels / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D016372:RNA, Antisense / Q000235:genetics*
D051656:KCNQ Potassium Channels; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D016372:RNA, Antisense; D004247:DNA; D003850:Deoxyribonuclease I