Mir-9/mir-79 microRNA precursor family

The miR-9 microRNA (homologous to miR-79), is a short non-coding RNA gene involved in gene regulation. The mature ~21nt miRNAs are processed from hairpin precursor sequences by the Dicer enzyme. The dominant mature miRNA sequence is processed from the 5' arm of the mir-9 precursor, and from the 3' arm of the mir-79 precursor. The mature products are thought to have regulatory roles through complementarity to mRNA.^[1] In vertebrates, miR-9 is highly expressed in the brain, and is suggested to regulate neuronal differentiation.^[2] A number of specific targets of miR-9 have been proposed, including the transcription factor REST and its partner CoREST.^[3]

mir-9
miR-9 microRNA secondary structure and sequence conservation.
Identifiers
Symbol	mir-9
Rfam	RF00237
miRBase family	MIPF0000014
HGNC	31641
OMIM	611186
Other data
RNA type	microRNA
Domain(s)	Eukaryota;
PDB structures	PDBe

Species distribution

miR-9 has been identified in Drosophila (MI0000129),^[4] mouse (MI0000720) and human (MI0000466),^[5] and the related miR-79 in C. elegans (MI0000050) ^[6] and Drosophila melanogaster (MI0000374).^[7]

Role in disease

microRNAs have been implicated in human cancer in a number of studies. It has been shown that human miR-9 expression levels are reduced in many breast cancer samples due to hypermethylation an epigenetic modification.^[8] Hildebrandt et al. show that two genes encoding for has-miR-9 are significantly hypermethylated in clear cell renal carcinoma tumours.^[9]