Mir-9/mir-79 microRNA precursor family

The miR-9 microRNA precursor (homologous to miR-79), is a short non-coding RNAgene involved in gene regulation. miR-9 has been identified in Drosophila ( [http://microrna.sanger.ac.uk/cgi-bin/sequences/mirna_entry.pl?acc=MI0000129 MI0000129] ) cite journal |author=Lagos-Quintana M, Rauhut R, Lendeckel W, Tuschl T |title=Identification of novel genes coding for small expressed RNAs |journal=Science |volume=294 |issue=5543 |pages=853–8 |year=2001 |pmid=11679670 |doi=10.1126/science.1064921] , mouse ( [http://microrna.sanger.ac.uk/cgi-bin/sequences/mirna_entry.pl?acc=MI0000720 MI0000720] ) and human ( [http://microrna.sanger.ac.uk/cgi-bin/sequences/mirna_entry.pl?acc=MI0000466 MI0000466] ) cite journal |author=Lagos-Quintana M, Rauhut R, Yalcin A, Meyer J, Lendeckel W, Tuschl T |title=Identification of tissue-specific microRNAs from mouse |journal=Curr. Biol. |volume=12 |issue=9 |pages=735–9 |year=2002 |pmid=12007417 |doi=] , and the related miR-79 in C. elegans ( [http://microrna.sanger.ac.uk/cgi-bin/sequences/mirna_entry.pl?acc=MI0000050 MI0000050] ) cite journal |author=Lau NC, Lim LP, Weinstein EG, Bartel DP |title=An abundant class of tiny RNAs with probable regulatory roles in Caenorhabditis elegans |journal=Science |volume=294 |issue=5543 |pages=858–62 |year=2001 |pmid=11679671 |doi=10.1126/science.1065062] and "Drosophila melanogaster" ( [http://microrna.sanger.ac.uk/cgi-bin/sequences/mirna_entry.pl?acc=MI0000374 MI0000374] ) cite journal |author=Sempere LF, Sokol NS, Dubrovsky EB, Berger EM, Ambros V |title=Temporal regulation of microRNA expression in Drosophila melanogaster mediated by hormonal signals and broad-Complex gene activity |journal=Dev. Biol. |volume=259 |issue=1 |pages=9–18 |year=2003 |pmid=12812784 |doi=] . The mature ~21nt miRNAs are processed from hairpin precursor sequences represented here. miR-9 is processed from the 5' arm of its precursor, and miR-79 from the 3' arm. The bounds of the precursors are predicted based on conservation and base pairing and are not generally known.
microRNAs are transcribed as ~70 nucleotideprecursors and subsequently processed by the Dicer enzyme to givea ~22 nucleotide product. The mature products are thought to haveregulatory roles through complementarity to mRNA cite journal |author=Ambros V |title=microRNAs: tiny regulators with great potential |journal=Cell |volume=107 |issue=7 |pages=823–6 |year=2001 |pmid=11779458 |doi=] .

microRNAs have been implicated in human cancer in a number of studies. Generally microRNA expression levels are reduced. It has been shown that human miR-9 expression levels are reduced in many breast cancer samples due to hypermethylation an epigenetic modification.cite journal | author = Lehmann U, Hasemeier B, Christgen M, "et al" | title = Epigenetic inactivation of microRNA gene hsa-mir-9-1 in human breast cancer | journal = | volume = | issue = | pages = | year = 2007 | pmid = 17948228 | doi = 10.1002/path.2251 | issn = ]

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