Fig. 1. The structure of human pri-miRNAs. (A) Two examples of miRNAs with their
own transcription units, such as miR-21 and the polycistronic
miR-17–92-1 cluster (Cai et al.,
2004; He et al.,
2005). (B) miRNAs that are transcribed with other genes.
miR-15a
16-1 resides in the intron of a non-coding RNA (ncRNA)
(Calin et al., 2004) and
miR-106b9325 lies in the intron of a protein-coding RNA
(Rodriguez et al., 2004).
miR-155 is found in the exon of a ncRNA
(Eis et al., 2005), whereas
miR-198 is in the exon of a protein-coding mRNA
(Cullen, 2004). DLEU2, deleted
in lymphocytic leukemia 2; MCM7, minichromosome maintenance deficient 7; BIC,
B-cell integration cluster; FSTL1, follistatin-like 1.