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The Let-7 microRNA precursor was identified from a study of developmental timing in C. elegans, and was later shown to be part of a much larger class of non-coding RNAs termed microRNAs. miR-98 microRNA precursor from human is a let-7 family member. Let-7 miRNAs have now been predicted or experimentally confirmed in a wide range of species (MIPF0000002). miRNAs are initially transcribed in long transcripts called primary miRNAs (pri-miRNAs), which are processed in the nucleus by Drosha and Pasha to hairpin structures of about 70 nucleotide. These precursors (pre-miRNAs) are exported to the cytoplasm by exportin5, where they are subsequently processed by the enzyme Dicer to a ~22 nucleotide mature miRNA. The involvement of Dicer in miRNA processing demonstrates a relationship with the phenomenon of RNA interference.
The miR-9 microRNA, is a short non-coding RNA gene involved in gene regulation. The mature ~21nt miRNAs are processed from hairpin precursor sequences by the Dicer 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 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.
There are 89 known sequences today in the microRNA 19 (miR-19) family but it will change quickly. They are found in a large number of vertebrate species. The miR-19 microRNA precursor is a small non-coding RNA molecule that regulates gene expression. Within the human and mouse genome there are three copies of this microRNA that are processed from multiple predicted precursor hairpins:
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 and later verified experimentally. 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.
MiR-155 is a microRNA that in humans is encoded by the MIR155 host gene or MIR155HG. MiR-155 plays a role in various physiological and pathological processes. Exogenous molecular control in vivo of miR-155 expression may inhibit malignant growth, viral infections, and enhance the progression of cardiovascular diseases.
In molecular biology mir-126 is a short non-coding RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several pre- and post-transcription mechanisms.
In molecular biology mir-143 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms. mir–143 is highly conserved in vertebrates. mir-143 is thought be involved in cardiac morphogenesis but has also been implicated in cancer.
In molecular biology, mir-145 microRNA is a short RNA molecule that in humans is encoded by the MIR145 gene. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
miR-31 has been characterised as a tumour suppressor miRNA, with its levels varying in breast cancer cells according to the metastatic state of the tumour. From its typical abundance in healthy tissue is a moderate decrease in non-metastatic breast cancer cell lines, and levels are almost completely absent in mouse and human metastatic breast cancer cell lines. Mir-31-5p has also been observed upregulated in Zinc Deficient rats compared to normal in ESCC and in other types of cancers when using this animal model. There has also been observed a strong encapsulation of tumour cells expressing miR-31, as well as a reduced cell survival rate. miR-31's antimetastatic effects therefore make it a potential therapeutic target for breast cancer. However, these two papers were formally retracted by the authors in 2015.
miR-146 is a family of microRNA precursors found in mammals, including humans. The ~22 nucleotide mature miRNA sequence is excised from the precursor hairpin by the enzyme Dicer. This sequence then associates with RISC which effects RNA interference.
In molecular biology mir-339 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms. miR-339-5p expression was associated with overall survival in breast cancer.
In molecular biology mir-340 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
In molecular biology mir-365 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
In molecular biology, microRNAs function to regulate the expression levels of other genes by several mechanisms. The miR-449 microRNA family encompasses three homologous small RNA molecules (miR-449a/b/c). This miR-449 cluster is located in the second intron of the CDC20B gene which both are co-transcribed. This miR-449 family belongs to the miR-34/miR-449 superfamily of microRNAs that is composed of six homologous miRNAs, named miR-34a/b/c and miR-449a/b/c.They are grouped together in the same superfamily, as their seed region and their adjacent nucleotide sequences are largely conserved. The miR-449 miRNAs control the differentiation of multiciliated cells in vertebrates.
In molecular biology mir-186 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
mir-616 microRNA is a short non-coding RNA molecule belonging both to the family of microRNAs and to that of small interfering RNAs (siRNAs). MicroRNAs function to regulate the expression levels of other genes by several mechanisms, whilst siRNAs are involved primarily with the RNA interference (RNAi) pathway. miR-616 has been found to induce the specifically androgen-independent growth of prostate cancer cells.
In molecular biology mir-625 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms. Many microRNAs play important roles in cancer development and progression.
In molecular biology mir-663 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
In molecular biology mir-938 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
miR-324-5p is a microRNA that functions in cell growth, apoptosis, cancer, epilepsy, neuronal differentiation, psychiatric conditions, cardiac disease pathology, and more. As a microRNA, it regulates gene expression through targeting mRNAs. Additionally, miR-324-5p is both an intracellular miRNA, meaning it is commonly found within the microenvironment of the cell, and one of several circulating miRNAs found throughout the body. Its presence throughout the body both within and external to cells may contribute to miR-324-5p's wide array of functions and role in numerous disease pathologies – especially cancer – in various organ systems.
References
- ↑ Ohdaira H, Nakagawa H, Yoshida K (2009). "Profiling of molecular pathways regulated by microRNA 601". Computational Biology and Chemistry. 33 (6): 429–33. doi:10.1016/j.compbiolchem.2009.09.003. PMID 19889580.
- ↑ Yao Y, Suo AL, Li ZF, Liu LY, Tian T, Ni L, et al. (2009). "MicroRNA profiling of human gastric cancer". Molecular Medicine Reports. 2 (6): 963–70. doi: 10.3892/mmr_00000199 . PMID 21475928.
