miRiad roles for the miR-17-92 cluster in development and disease

Abstract

MicroRNAs (miRNAs) encoded by the miR-17-92 cluster and its paralogs are known to act as oncogenes. Expression of these miRNAs promotes cell proliferation, suppresses apoptosis of cancer cells, and induces tumor angiogenesis. New work reveals essential functions for these miRNAs not only in tumor formation but also during normal development of the heart, lungs, and immune system.

Figure 1. Organization of the miR-17-92 cluster and its paralogs

(A) The genomic organization and primary transcript structures of the human miR-17-92, miR-106a-363, and miR-106b-25 clusters. The miR-106a-363 primary transcript has not been characterized. (B) Based on their seed sequences, the region considered most important for target selection (nucleotides 2–7; shown in blue), the miRNAs of these clusters can be grouped into four families: the miR-17 family (miR-17, miR-20a/b, miR-106a/b, and miR-93); the miR-18 family (miR-18a/b); the miR-19 family (miR-19a/b); and the miR-25 family (miR-25, miR-92a, and miR-363). MicroRNAs of the miR-17-92 cluster and its paralogs have been implicated in normal development of the heart, lungs and immune system as well as in tumorigenesis.