This family represents the microRNA (miRNA) precursor mir-7. This miRNA has been predicted or experimentally confirmed in a wide range of species. miRNAs are transcribed as ~70 nucleotide

Nucleotide

Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...

 precursors (modelled here) and subsequently processed by the Dicer

Dicer

Dicer is an endoribonuclease in the RNase III family that cleaves double-stranded RNA and pre-microRNA into short double-stranded RNA fragments called small interfering RNA about 20-25 nucleotides long, usually with a two-base overhang on the 3' end...

 enzyme to give a ~22 nucleotide product. In this case the mature sequence comes from the 5' arm of the precursor. The extents of the hairpin precursors are not generally known and are estimated based on hairpin prediction. The involvement of Dicer in miRNA processing suggests a relationship with the phenomenon of RNA interference.

Mature miRNA-7 is derived from three microRNA precursors in the human genome, miR-7-1, miR-7-2 and miR-7-3. miRNAs are numbered based on the sequence of the mature RNA.

miR-7 is directly regulated by the transcription factor HoxD10.

miRNAs are thought to have regulatory roles through complementarity to mRNA.
miR-7 is essential for the maintenance of regulatory stability under conditions of environmental flux. It plays an important role in controlling mRNA expression. The miR-7 gene is found in most sequenced Urbilateria species, and the sequence of its mature miRNA product is perfectly conserved from annelid

Annelid

The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...

s to humans, indicating a strong functional conservation.

Targets of miR-7

Bioinformatic predictions suggest that the human EGFR mRNA 3'-untranslated region contains three microRNA-7 (miR-7) target sites, which are not conserved across mammals. In Drosophila photoreceptor cells, miR-7 controls epidermal growth factor receptor (EGFR) signaling and promotes photoreceptor differentiation. Among other targets of miR-7 are insulin-like growth factor 1 receptor (IGF1R) and PIK3CD, E(spl) gene family and Pak1 (cancer cells). c-Fos

C-Fos

In the field of molecular biology and Genetics, c-Fos is a protein encoded by the FOS gene.-Structure and function:c-Fos is a cellular proto-oncogene belonging to the immediate early gene family of transcription factors. c-Fos has a leucine-zipper DNA binding domain, and a transactivation domain at...

is also a target of miR-7b in mice.

Clinical relevance

Multiple roles and targets of miR-7 as well as its expression pattern were linked to regulatory mechanisms and pathogenesis in glioblastoma, breast cancer and other types of cancers, as well as in schizophrenia and visual abnormalities. Inhibition of the motility, invasiveness, anchorage-independent growth, and tumorigenic potential of highly invasive breast cancer cells through the introduction of miR-7 suggests a strong therapeutic potential of miR-7.