The miR-9 microRNA (
homologous to miR-79), is a short
non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not Translation (genetics), translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally imp ...
gene involved in
gene regulation
Regulation of gene expression, or gene regulation, includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA). Sophisticated programs of gene expression are wide ...
. The mature ~21nt miRNAs are processed from hairpin precursor sequences by the
Dicer
Dicer, also known as endoribonuclease Dicer or helicase with RNase motif, is an enzyme that in humans is encoded by the gene. Being part of the RNase III family, Dicer cleaves double-stranded RNA (dsRNA) and pre-microRNA (pre-miRNA) into shor ...
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
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein.
mRNA is ...
.
In vertebrates, miR-9 is highly expressed in the brain, and is suggested to regulate neuronal differentiation.
A number of specific targets of miR-9 have been proposed, including the transcription factor REST and its partner CoREST.
Species distribution
miR-9 has been identified in Drosophila
MI0000129,
mouse
MI0000720 and human
MI0000466,
and the related miR-79 in C. elegans
MI0000050 and ''Drosophila melanogaster''
MI0000374.
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
Breast cancer is a cancer that develops from breast tissue. Signs of breast cancer may include a Breast lump, lump in the breast, a change in breast shape, dimpling of the skin, Milk-rejection sign, milk rejection, fluid coming from the nipp ...
samples due to
hypermethylation
Methylation, in the chemical sciences, is the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These terms ...
an
epigenetic
In biology, epigenetics is the study of changes in gene expression that happen without changes to the DNA sequence. The Greek prefix ''epi-'' (ἐπι- "over, outside of, around") in ''epigenetics'' implies features that are "on top of" or "in ...
modification.
Hildebrandt ''et al''. show that two genes encoding for has-miR-9 are significantly hypermethylated in clear cell renal carcinoma tumours.
References
Further reading
External links
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{{DEFAULTSORT:Mir-9 Mir-79 Microrna Precursor Family
MicroRNA
MicroRNA precursor families