mRNA and miRNA: What Are They and How Do They Work?
Abstract:
This Article explores the differences between mRNA and miRNA, two important types of RNA that play distinct roles in gene expression. mRNA carries genetic information from DNA to the ribosomes for protein synthesis, while miRNA regulates gene expression by controlling mRNA stability and translation. The article explains the functions of each type of RNA in detail and their roles in various biological processes, as well as their potential therapeutic applications. The article also touches upon recent advances in technology that have allowed researchers to study these types of RNA in greater detail, leading to a better understanding of their functions. Finally, the article highlights the importance of understanding the roles of mRNA and miRNA in advancing our knowledge of biology and developing new therapies for a variety of diseases.
Introduction:
RNA, or ribonucleic acid, is a type of nucleic acid that plays a crucial role in gene expression. There are many different types of RNA, but two of the most important are mRNA (messenger RNA) and miRNA (microRNA). These two types of RNA have different functions and are involved in different aspects of gene expression. In this blog post, we'll take a closer look at mRNA and miRNA, what they are, how they work, and why they are important.
mRNA: The Messenger Between DNA and Proteins:
mRNA, as its name suggests, is responsible for carrying messages from DNA to the ribosomes, where proteins are synthesized. In eukaryotic cells, mRNA is synthesized in the nucleus from a DNA template, and then it is transported out of the nucleus into the cytoplasm, where it is translated into proteins. This process is known as transcription and translation.
The structure of mRNA is relatively simple. It consists of a single-stranded chain of nucleotides, each of which is made up of a sugar, a phosphate group, and a nitrogenous base. The nitrogenous bases are adenine, uracil, guanine, and cytosine. mRNA is transcribed from DNA, with the nucleotide sequence in the mRNA molecule determined by the complementary base pairing of the DNA template.
The function of mRNA is to carry the genetic information from DNA to the ribosomes, where it is used to synthesize proteins. The nucleotide sequence of the mRNA determines the amino acid sequence of the protein that is produced. There are three nucleotides in mRNA, called codons, that correspond to each amino acid. The ribosome reads the mRNA codons and uses the genetic code to assemble a protein from amino acids.
miRNA: Regulating Gene Expression:
miRNA, on the other hand, is a type of RNA that regulates gene expression. miRNA is transcribed from DNA, just like mRNA, but it has a different function. miRNA molecules are relatively small, consisting of only about 20-22 nucleotides. Unlike mRNA, miRNA does not encode proteins.
miRNA functions by binding to specific mRNA molecules and preventing their translation into protein. miRNA does this by either promoting the degradation of the mRNA or by blocking the translation of the mRNA into protein. This regulation of gene expression by miRNA is important in many biological processes, including development, differentiation, metabolism, and disease pathogenesis.
miRNA is produced in a two-step process. First, an initial miRNA molecule, called a primary miRNA transcript, is synthesized from DNA. This primary miRNA transcript is then processed by an enzyme called Dicer, which cleaves it into a smaller miRNA molecule. The resulting miRNA molecule is then incorporated into a complex called the RNA-induced silencing complex (RISC), which is responsible for binding to target mRNA molecules and regulating their expression.
miRNA has been shown to be involved in many different biological processes. For example, miRNA-21 has been shown to play a role in cancer cell proliferation and metastasis (1). miRNA-146a is involved in immune regulation and inflammation (2). miRNA dysregulation has also been implicated in many diseases, including cancer, cardiovascular disease, and neurodegenerative diseases (3).
Difference between mRNA and miRNA:
Conclusion:
In conclusion, mRNA and miRNA are two important types of RNA that play distinct roles in gene expression. While mRNA carries genetic information from DNA to the ribosomes for protein synthesis, miRNA regulates gene expression by controlling mRNA stability and translation. Understanding the roles of these types of RNA is important for advancing our understanding of biology and developing new therapies for a variety of diseases.
References:
1. Di Leva, G., & Garofalo, M. (2014). miRNA signatures of cancer. EMBO Molecular Medicine, 6(8), 971–983. https://doi.org/10.15252/emmm.201100937
2. O’Connell, R. M., Rao, D. S., & Baltimore, D. (2012). microRNA regulation of inflammatory responses. Annual Review of Immunology, 30(1), 295–312. https://doi.org/10.1146/annurev-immunol-020711-075013
3. Bartel, D. P. (2009). MicroRNAs: Target Recognition and Regulatory Functions. Cell, 136(2), 215–233. https://doi.org/10.1016/j.cell.2009.01.002
4. Polack, F. P., Thomas, S. J., Kitchin, N., Absalon, J., Gurtman, A., Lockhart, S., Perez, J. L., Pérez Marc, G., Moreira, E. D., Zerbini, C., Bailey, R., Swanson, K. A., Roychoudhury, S., Koury, K., Li, P., Kalina, W. V., Cooper, D., Frenck, R. W. Jr, … Gruber, W. C. (2020). Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. New England Journal of Medicine, 383(27), 2603–2615. https://doi.org/10.1056/nejmoa2034577
5. Rupaimoole, R., & Slack, F. J. (2017). MicroRNA therapeutics: Towards a new era for the management of cancer and other diseases. Nature Reviews Drug Discovery, 16(3), 203–222. https://doi.org/10.1038/nrd.2016.246
