Long Noncoding RNAs
The past 5 years have uncovered thousands of long (>100 nucleotides) noncoding RNAs (lncRNAs) outpacing our understanding of their functions and mechanisms in regulating the genome.
Lee
(p.
1435
) reviews the known and suspected means by which these intriguing molecules control gene expression locally and at great distances, considers potential universal roles for lncRNAs, and warns that classifying these intriguing molecules may be quite challenging given their diversity. The very long noncoding RNA,
Airn
, silences the
Igf2r
(insulin-like growth factor 2 receptor) imprinted gene cluster in mammals.
Latos
et al.
(p.
1469
) show in mouse cells that, rather than recruiting enzymes that modify histones to repress the locus, it is the act of transcription of
Airn
(and not the
Airn
gene product) that results in the silencing.