Mir-22
Encyclopedia
In molecular biology mir-22 microRNA is a short RNA
molecule. MicroRNAs are an abundant class of molecules, approximately 22 nucleotide
s in length, which can post-transcriptionally regulate gene expression by binding to the 3’ UTR
of mRNAs expressed in a cell.
cells (an immortal cell line derived from cervical cancer cells), but was later found to be ubiquitously expressed in various tissues. The gene encoding miR-22 is found on the short arm of chromosome 17, in a minimal loss of heterozygosity region. It is highly conserved across many vertebrate species, including chimp, mouse, rat, dog and horse. This level of conservation suggests functional importance. MiR-22 was previously identified as having a role in erythrocyte maturation.
, multiple myeloma
and hepatocellular carcinoma
.
4 (HDAC4), which is known to have a critical role in cancer development. Mir-22 also targets Myc
Binding Protein (MYCBP). This prevents transcription of c-Myc target genes by silencing c-MYCBP. However, c-Myc also inhibits expression of miR-22 in a positive feedback loop. When this spirals out of control, it can cause uncontrolled cell proliferation.
Non-coding RNA
A non-coding RNA is a functional RNA molecule that is not translated into a protein. Less-frequently used synonyms are non-protein-coding RNA , non-messenger RNA and functional RNA . The term small RNA is often used for short bacterial ncRNAs...
molecule. MicroRNAs are an abundant class of molecules, approximately 22 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...
s in length, which can post-transcriptionally regulate gene expression by binding to the 3’ UTR
Three prime untranslated region
In molecular genetics, the three prime untranslated region is a particular section of messenger RNA . It is preceeded by the coding region....
of mRNAs expressed in a cell.
Origins
Mir-22 was originally identified in HeLaHeLa
A HeLa cell is a cell type in an immortal cell line used in scientific research. It is the oldest and most commonly used human cell line. The line was derived from cervical cancer cells taken on February 8, 1951 from Henrietta Lacks, a patient who eventually died of her cancer on October 4, 1951...
cells (an immortal cell line derived from cervical cancer cells), but was later found to be ubiquitously expressed in various tissues. The gene encoding miR-22 is found on the short arm of chromosome 17, in a minimal loss of heterozygosity region. It is highly conserved across many vertebrate species, including chimp, mouse, rat, dog and horse. This level of conservation suggests functional importance. MiR-22 was previously identified as having a role in erythrocyte maturation.
Role in cancer
The deregulation of many miRNAs has been shown to have a role in oncogenesis. Mir-22 was found to be over-expressed in prostate cancer but down-regulated in breast cancer, cholangiocarcinomaCholangiocarcinoma
Cholangiocarcinoma is a cancer of the bile ducts which drain bile from the liver into the small intestine. Other biliary tract cancers include pancreatic cancer, gallbladder cancer, and cancer of the ampulla of Vater...
, multiple myeloma
Multiple myeloma
Multiple myeloma , also known as plasma cell myeloma or Kahler's disease , is a cancer of plasma cells, a type of white blood cell normally responsible for the production of antibodies...
and hepatocellular carcinoma
Hepatocellular carcinoma
Hepatocellular carcinoma is the most common type of liver cancer. Most cases of HCC are secondary to either a viral hepatitide infection or cirrhosis .Compared to other cancers, HCC is quite a rare tumor in the United States...
.
Targets
Specifically, miR-22 can function as a tumour suppressor. One known target is histone deacetylaseHistone deacetylase
Histone deacetylases are a class of enzymes that remove acetyl groups from an ε-N-acetyl lysine amino acid on a histone. This is important because DNA is wrapped around histones, and DNA expression is regulated by acetylation and de-acetylation. Its action is opposite to that of histone...
4 (HDAC4), which is known to have a critical role in cancer development. Mir-22 also targets Myc
Myc
Myc is a regulator gene that codes for a transcription factor. In the human genome, Myc is located on chromosome 8 and is believed to regulate expression of 15% of all genes through binding on Enhancer Box sequences and recruiting histone acetyltransferases...
Binding Protein (MYCBP). This prevents transcription of c-Myc target genes by silencing c-MYCBP. However, c-Myc also inhibits expression of miR-22 in a positive feedback loop. When this spirals out of control, it can cause uncontrolled cell proliferation.