LIT1, an imprinted antisense RNA in the human KvLQT1 locus identified by screening for differentially expressed transcripts using monochromosomal hybrids.
Mammalian imprinted genes are frequently arranged in clusters on particular chromosomes. The imprinting cluster on human chromosome 11p15 is associated with Beckwith-Wiedemann syndrome (BWS) and a variety of human cancers. To clarify the genomic organization of the imprinted cluster, an extensive screen for differentially expressed transcripts in the 11p15 region was performed using monochromosomal hybrids with a paternal or maternal human chromosome 11. Here we describe an imprinted antisense transcript identified within the KvLQT1 locus, which is associated with multiple balanced chromosomal rearrangements in BWS and an additional breakpoint in embryonal rhabdoid tumors. The transcript, called LIT1 (long QT intronic transcript 1), was expressed preferentially from the paternal allele and produced in most human tissues. Methylation analysis revealed that an intronic CpG island was specifically methylated on the silent maternal allele and that four of 13 BWS patients showed complete loss of maternal methylation at the CpG island, suggesting that antisense regulation is involved in the development of human disease. In addition, we found that eight of eight Wilms' tumors exhibited normal imprinting of LIT1 and five of five tumors displayed normal differential methylation at the intronic CpG island. This contrasts with five of six tumors showing loss of imprinting of IGF2. We conclude that the imprinted gene domain at the KvLQT1 locus is discordantly regulated in cancer from the imprinted domain at the IGF2 locus. Thus, this positional approach using human monochromosomal hybrids could contribute to the efficient identification of imprinted loci in humans.
Mitsuya
K
K
Department of Molecular and Cell Genetics, School of Life Sciences, Faculty of Medicine, Tottori University, Nishimachi, Yonago, Japan.
Meguro
M
M
Lee
M P
MP
Katoh
M
M
Schulz
T C
TC
Kugoh
H
H
Yoshida
M A
MA
Niikawa
N
N
Feinberg
A P
AP
Oshimura
M
M
D000818:Animals; D001483:Base Sequence; D001506:Beckwith-Wiedemann Syndrome / Q000235:genetics*; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D005347:Fibroblasts / Q000502:physiology; D018392:Genomic Imprinting; D006801:Humans; D006822:Hybrid Cells; D007438:Introns; D051656:KCNQ Potassium Channels; D051657:KCNQ1 Potassium Channel; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000096:biosynthesis / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D016372:RNA, Antisense / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D016415:Sequence Alignment; D009396:Wilms Tumor / Q000235:genetics
D051656:KCNQ Potassium Channels; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; C485621:KCNQ1OT1 long non-coding RNA, human; C496910:Kcnq1 protein, mouse; D008565:Membrane Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D016372:RNA, Antisense; D012333:RNA, Messenger