Minsu Kim/minsu1

what is MicroRNA?

A microRNA (miRNA) is a small non-coding RNA molecule (containing about 22 nucleotides) found in plants, animals and some viruses, that functions in RNA silencing and post-transcriptional regulation of gene expression. miRNA are encoded in the genome as segments of longer transripts. their characteristic structure helps identify them and predict the target genes they might regulate. 

 

Synthesis and Function of miRNA

Structure of pre-miRNAs

overview of the structure of pri-miRNA showing cleavage

miRNAs are derived from precursor RNAs that are encoded by genes. their characteristic structure helps identify them and predict the target genes they might regulate. the functional form of a miRNA IS typically ~21 or 22 nucleotides. These short RNAs are generated by two RNA cleavage reactions from a longer RNA transcript (called a pri-RNA,  for "primary") that carries a hairpin-shaped scondary structure. The first cleavage liverates the stem- loop, called the pre-miRNA ; the second generates the mature miRNA from the pre-miRNA. The two cleavage reactions required to generate the miRNA grom these primary trnascipts are mediated by tow distinct RNases. One is Dicer, and the others is Drosha

miRNAs function via base-pairing with complementary sequences within mRNA. As a result, these mRNA molecules are silenced, by one or more of the following processes:

 

• To trigger destruction of the mRNA
• To interfere with translation of the mRNA
• Less efficient translation of the mRNA into proteins by ribosomes

 

miRNAs resemble the small interfering RNAs (siRNAs) of the RNA interference (RNAi) pathway, except miRNAs derive from regions of RNA transcripts that fold back on themselves to form short hairpins, whereas siRNAs derive from longer regions of double-stranded RNA. The human genome may encode over 1000 miRNAs, which are abundant in many mammalian cell types and appear to target about 60% of the genes of humans and other mammals

 

 

ESSAY

Can miRNA be available for a therapy about an intractable disease associated with a gene?

 

Abstract

Many disease is related with gene that express the some protein. And MicroRNA(miRNA) is a kind of regulatory gene. It can repress the gene expression. Recently gene therapy is developed. If so miRNA can be one of the treatments about an intractable disease associated with a gene.

Introduction

Gene is the most central element to produce proteins in the body. Gene control how cell work by making proteins that have specific functions and act as messengers for the cell. Therefore, each gene must not have some errors. This is so the protein can perform the correct function for the cell. But many disease is caused by the gene that makes the some proteins. For example, cancer begins when one or more genes in a cell are mutated, or changed. This creates an abnormal protein or no protein at all. An abnormal protein provides different information than a normal protein, which can cause cells to multiply uncontrollably and become cancerous. Thus, our bodies are determined in the expression of genes. However, there is also a mechanism in the body that prevents the expression of the gene. MicroRNA(miRNA) is a kind of regulatory gene, that functions in RNA silencing and post-transcriptional regulation of gene expression. their characteristic structure helps identify them and predict the target genes they might regulate.  If so miRNA can be one of the treatments about an intractable disease associated with a gene. Because miRNA can be specified target gene and interfere the translation of proteins by ribosome.

Actually miRNA is related with the cancer.

When we look at the relationship between Mirna and cancer, they actually have quite a lot of relationships. MiRNA are generally downregulated in cancer. Some people already have GENE, which causes CANCER, and many miRNAs are involved and blocking its expression. This was demonstrated in a MOUSE MODEL experiment. Over the past decade, the degree to which miRNAs are involved in cancer has really become apparent. As has the sheer diversity of mechanisms by which miRNA function is deregulated, the major general causes of altered miRNA expression in cancer are discussed below and summarised in Figure.

If so, can these mutated miRNAs be treated and replaced?

Cancer gene therapy is already underway.

Many researchers are studying the nature of cancer and genes, and miRNA-based therapies are under development. Although it is still a trial and error step, and there are many difficulties, it is expected that perfect miRNA TREATMENTS will be developed if precise cause of GENE and CANCER is identified.

Conclusion

MiRNA can be one of the treatments about an intractable disease like the cancer. Already many scientists study the source of cancer and miRNA. Although the gene therapy is not perfect, it has a potential as a treatment.

 

Reference

https://en.wikipedia.org/wiki/MicroRNA#Target_prediction		http://www.ibric.org/myboard/read.php?Board=report&id=2489
MicroRNA and cancer Martin D. Jansson, Anders H. Lund* Biotech Research and Innovation Centre and Centre for Epigenetics, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark		https://www.cancer.net/navigating-cancer-care/cancer-basics/genetics/genetics-cancer
molecular biology of the gene seventh edition-pearson		http://www.kosen21.org/info/kosenReport/reportView.do?articleSeq=759471
https://www.nature.com/cgt/about/