mir-34 microRNA precursor family | |
---|---|
Identifiers | |
Symbol | mir-34 |
Rfam | RF00456 |
miRBase | MI0000268 |
miRBase family | MIPF0000039 |
Other data | |
RNA type | Gene; miRNA |
Domain(s) | Eukaryota |
GO | GO:0035195 GO:0035068 |
SO | SO:0001244 |
PDB structures | PDBe |
The miR-34 microRNA precursor family are non-coding RNA molecules that, in mammals, give rise to three major mature miRNAs. The miR-34 family members were discovered computationally [1] and later verified experimentally. [2] [3] The precursor miRNA stem-loop is processed in the cytoplasm of the cell, with the predominant miR-34 mature sequence excised from the 5' arm of the hairpin. [4]
In mammals, three miR-34 precursors are produced from two transcriptional units. [5] The human miR-34a precursor is transcribed from chromosome 1. The miR-34b and miR-34c precursors are co-transcribed from a region on chromosome 11, apparently as part of a transcript known as BC021736.
Expression of MIR34A (gene) in mouse is observed in all tissues examined but is highest in brain. miR-34b and -c are relatively less abundant in most tissues, but are the predominant miR-34 species in lung. [5] The presence of miR-34 products has also been confirmed in embryonic stem cells. miR-34 has been shown to be maternally inherited in Drosophila and zebrafish and the loss of miR-34 resulted in defects in hindbrain development in zebrafish embryos. This was the first report of knockdown phenotype of miR-34 in any model organism although the phenotype was observed in only about 30% of zebrafish embryos. [6]
Yamakuchi et al.. showed that miR-34a targets the silent information regulator 1 (SIRT1) gene: [7]
Recently Quantitative proteomics – SILAC approach was used to identify miR-34a targets at genome level in HEK293T cells. [8]
p53-deficient human gastric cancer cells, restoration of functional miR-34 inhibits cell growth and induces chemosensitization and apoptosis, indicating that miR-34 may restore p53 function. Restoration of miR-34 inhibits tumorsphere formation and growth, which is reported to be correlated to the self-renewal of cancer stem cells. The mechanism of miR-34-mediated suppression of self-renewal appears to be related to the direct modulation of downstream targets Bcl-2, Notch, and HMGA2, indicating that miR-34 may be involved in gastric cancer stem cell self-renewal/differentiation decision-making. [9] [10] miR-34c has also been associated to bone development and bone cancer. [11]
The miR-192 microRNA precursor, is a short non-coding RNA gene involved in gene regulation. miR-192 and miR-215 have now been predicted or experimentally confirmed in mouse and human.
The mir-10 microRNA precursor is a short non-coding RNA gene involved in gene regulation. It is part of an RNA gene family which contains mir-10, mir-51, mir-57, mir-99 and mir-100. mir-10, mir-99 and mir-100 have now been predicted or experimentally confirmed in a wide range of species. miR-51 and miR-57 have currently only been identified in the nematode Caenorhabditis elegans.
The miR-129 microRNA precursor is a small non-coding RNA molecule that regulates gene expression. This microRNA was first experimentally characterised in mouse and homologues have since been discovered in several other species, such as humans, rats and zebrafish. The mature sequence is excised by the Dicer enzyme from the 5' arm of the hairpin. It was elucidated by Calin et al. that miR-129-1 is located in a fragile site region of the human genome near a specific site, FRA7H in chromosome 7q32, which is a site commonly deleted in many cancers. miR-129-2 is located in 11p11.2.
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