mir-181 microRNA precursor

mir-181 microRNA precursor
GO		GO:0035195 GO:0035068
SO	SO:0001244
PDB structures	PDBe

In molecular biology miR-181 microRNA precursor is a small

).

Expression

It has been shown that miR-181 is preferentially expressed in the B-lymphoid cells of mouse bone marrow,^[3] but also in the retina and brain.^[4] In humans, this microRNA is involved in the mechanisms of immunity, and in many different cancers (see below) it was found to be expressed at a particularly low level.^[5]

Genome location

Human
miR-181a1 and miR-181b1 are clustered together and located on the

Organisms

miR-181 family are present in vertebrates and nematodes^{[citation needed]} (this list is not exhaustive):

miR-181

Chronic lymphocytic leukemia

miR-181 may have a regulatory role with tumor suppressors genes of the human chromosome 1.[5] It has been shown that the Tcl1 oncogene is a target of miR-181a in an inhibition relation (downregulated) that would result in an action on the tumor cell growth process. miR-181 expression has a reverse correlation with Tcl1 protein expression.^[31]

Neuroblastoma

mir-181 a and b are over-expressed and act as bad prognosis maker of aggressive neuroblastoma (Stage 4) as compare to low grade stage (Stage 1;2;3 and 4S) whereas mir-181 c and d isoforms are not. In these conditions, they regulate the tumor suppressor gene CDON.^[32]

Myoblast differentiation

It has been shown that miR-181 targets the homeobox protein Hox-A11 and participates in establishing muscle tissue downregulating it (a repressor of the differentiation process in mammalians and lower organisms).^[33]

Breast cancer

miR-181a, miR-181b, miR-181c and miR-181d are activated by the human gene

miR-181 is also activated by the small molecule tamoxifen.^[35] One selective modulators of estrogen receptor having specific activities of tissue. Tamoxifen acts as an anti-estrogen (inhibitor) in breast tissue, but as an estrogen (stimulating agent) in cholesterol metabolism, bone density, and the proliferation of endometrial cells. miR-181 could acquire a resistance to tamoxifen, the drug is successfully used to treat women with estrogen receptor-positive breast cancer.^[35]

Acute myeloid leukemia

Downregulation of miR-181 family contributes to aggressive

Glioblastoma

miR-181a, miR-181b, and miR-181c, which are down-regulated in glioblastoma.^[36] miR-181b is downregulated in glioma samples compared with the normal brain tissue. It is suggested that the downregulation of miR-181 may play a role in the development of cancer. It is shown that transfection of miR-181a and miR-181b triggers growth inhibition, apoptosis and inhibits invasion. In addition, the expression of miR-181a was found to be inversely correlated with tumor grading while miR-181b was uniformly downregulated in gliomas with different grades of malignancy.^[37]

Glioma

It has been shown that downregulated miR-181a and miR-181b were also involved in the oncogenesis of gliomas. miR-181a and miR-181b function as tumor suppressors that cause inhibition of growth, induce apoptosis and inhibit invasion of glioma cells. In addition, the tumor suppressive effect of miR-181b in glioma cells was apparent that the effect of miR-181a. These aberrant results suggest that downregulated miR-181a and miR-181b may be key factors that contribute to the occurrence in malignant human

Multiple myeloma

MiRNA signature for multiple

Papillary thyroid carcinoma

It was found that miR-181a and miR-181c are overexpressed in Papillary Thyroid Carcinoma tumors, sufficiently to successfully predict cancer status.^[40]

Hepatocellular carcinoma

It has been shown that conserved miR-181 family were upregulated in

miR-181a

T-cell sensitivity

The increased expression of miR-181a in mature

Vascular development

It has been shown that miR-181a binds the 3' UTR of Prox1 leading to translation repression and transcript degradation. Prox1 is a homeobox transcription factor involved in development of the lymphatic endothelium.^[43]

Cerebellar neurodegeneration

miR-181a has a relatively broad expression pattern and is present in neurons in numerous parts of the mouse brain. miR-181a is essential for the survival of

Diabetes mellitus

It has been shown that there are significant correlations between the expression of miR-181a and both adipose tissue morphology and key metabolic parameters, including visceral fat area,

Homozygous sickle cell disease

miR-181a is over-represented in the normal hemoglobin (HbAA) erythrocytes.[46] miR-181a has been shown to play a role in the lineage differentiation in the hematopoietic system.^[3]

Breast cancer

miR-181a expression is associated with survival in triple negative breast cancer. Patients with low expression have lower probability of survival over time.^[47]

miR-181b

Colorectal cancer

miR-181b was significantly overexpressed in tumors compared to normal colorectal samples, especially high miR-181b expression correlated with poor survival of only black patients with stage III colorectal cancers ^[48] (Sequencing analysis revealed that miR-181b expression is strongly associated with mutation status of the tumor suppressor gene p53.^[49]

Cardiac hypertrophy

miR-181b is downregulated during hypertrophy, it causes a reduction in cardiomyocyte cell size.^[50]

Oral carcinoma

miR-181b expression was steadily increased and is associated with increased severity of lesions during the progression of the Oral Carcinoma. Overexpression of miR-181b may play an important role in malignant transformation.^[51]

Prostate cancer

miR-181b is downregulated in cancerous cells.^[52]

Adrenocortical carcinoma

Mir-210 has been suggested as a useful biomarker to distinguish adrenocortical carcinoma from adrenocortical adenoma.^[53]

miR-181c

in Apoptosis^{[citation needed]}

miR-181d

Duchenne muscular dystrophy

miR-181d is disregulated in Duchenne muscular dystrophy (DMD).^[54]

Nemaline myopathy

miR-181d is disregulated in nemaline myopathy (NM).^[54]

References

Further reading

• Ambros V (December 2001). "microRNAs: tiny regulators with great potential". Cell. 107 (7): 823–6.
  PMID 11779458
  .
• Lagos-Quintana M, Rauhut R, Meyer J, Borkhardt A, Tuschl T (February 2003). "New microRNAs from mouse and human". RNA. 9 (2): 175–9.
  PMID 12554859
  .
• Safdar A, Abadi A, Akhtar M, Hettinga BP, Tarnopolsky MA (2009). "miRNA in the regulation of skeletal muscle adaptation to acute endurance exercise in C57Bl/6J male mice". PLOS ONE. 4 (5): e5610.
  PMID 19440340.
• Zhang B, Pan X (February 2009). "RDX induces aberrant expression of microRNAs in mouse brain and liver". Environmental Health Perspectives. 117 (2): 231–40.
  PMID 19270793
  .

External links

• Page for mir-181 microRNA precursor at Rfam
• MIPF0000007