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Template:Genetics sidebar Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyribonucleic acid (DNA) are nucleic acids. The nucleic acids constitute one of the four major macromolecules essential for all known forms of life. RNA is assembled as a chain of nucleotides. Cellular organisms use messenger RNA (mRNA) to convey genetic information (using the nitrogenous bases of guanine, uracil, adenine, and cytosine, denoted by the letters G, U, A, and C) that directs synthesis of specific proteins. Many viruses encode their genetic information using an RNA genome.
Some RNA molecules play an active role within cells by catalyzing biological reactions, controlling gene expression, or sensing and communicating responses to cellular signals. One of these active processes is protein synthesis, a universal function in which RNA molecules direct the synthesis of proteins on ribosomes. This process uses transfer RNA (tRNA) molecules to deliver amino acids to the ribosome, where ribosomal RNA (rRNA) then links amino acids together to form coded proteins.
It has become widely accepted in science<ref>Template:Cite journal</ref> that early in the history of life on Earth, prior to the evolution of DNA and possibly of protein-based enzymes as well, an "RNA world" existed in which RNA served as both living organisms' storage method for genetic information—a role fulfilled today by DNA, except in the case of RNA viruses—and potentially performed catalytic functions in cells—a function performed today by protein enzymes, with the notable and important exception of the ribosome, which is a ribozyme.
Chemical structure of RNAEdit
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Basic chemical compositionEdit
Each nucleotide in RNA contains a ribose sugar, with carbons numbered 1' through 5'. A base is attached to the 1' position, in general, adenine (A), cytosine (C), guanine (G), or uracil (U). Adenine and guanine are purines, and cytosine and uracil are pyrimidines. A phosphate group is attached to the 3' position of one ribose and the 5' position of the next. The phosphate groups have a negative charge each, making RNA a charged molecule (polyanion). The bases form hydrogen bonds between cytosine and guanine, between adenine and uracil and between guanine and uracil.<ref name="pmid15561141"/> However, other interactions are possible, such as a group of adenine bases binding to each other in a bulge,<ref>Template:Cite book</ref> or the GNRA tetraloop that has a guanine–adenine base-pair.<ref name="pmid15561141">Template:Cite journal</ref>
Differences between DNA and RNAEdit
Like DNA, most biologically active RNAs, including mRNA, tRNA, rRNA, snRNAs, and other non-coding RNAs, contain self-complementary sequences that allow parts of the RNA to fold<ref>Template:Cite journal</ref> and pair with itself to form double helices. Analysis of these RNAs has revealed that they are highly structured. Unlike DNA, their structures do not consist of long double helices, but rather collections of short helices packed together into structures akin to proteins.
In this fashion, RNAs can achieve chemical catalysis (like enzymes).<ref>Template:Cite journal</ref> For instance, determination of the structure of the ribosome—an RNA-protein complex that catalyzes the assembly of proteins—revealed that its active site is composed entirely of RNA.<ref name=ribosome_activity>Template:Cite journal</ref>
An important structural component of RNA that distinguishes it from DNA is the presence of a hydroxyl group at the 2' position of the ribose sugar. The presence of this functional group causes the helix to mostly take the A-form geometry,<ref>Template:Cite journal</ref> although in single strand dinucleotide contexts, RNA can rarely also adopt the B-form most commonly observed in DNA.<ref>Template:Cite journal</ref> The A-form geometry results in a very deep and narrow major groove and a shallow and wide minor groove.<ref>Template:Cite journal</ref> A second consequence of the presence of the 2'-hydroxyl group is that in conformationally flexible regions of an RNA molecule (that is, not involved in formation of a double helix), it can chemically attack the adjacent phosphodiester bond to cleave the backbone.<ref>Template:Cite journal</ref>
Secondary and tertiary structuresEdit
The functional form of single-stranded RNA molecules, just like proteins, frequently requires a specific spatial tertiary structure. The scaffold for this structure is provided by secondary structural elements that are hydrogen bonds within the molecule. This leads to several recognizable "domains" of secondary structure like hairpin loops, bulges, and internal loops.<ref>Template:Cite journal</ref> In order to create, i.e., design, RNA for any given secondary structure, two or three bases would not be enough, but four bases are enough.<ref>Template:Cite journal</ref> This is likely why nature has "chosen" a four base alphabet: fewer than four would not allow the creation of all structures, while more than four bases are not necessary to do so. Since RNA is charged, metal ions such as Mg2+ are needed to stabilise many secondary and tertiary structures.<ref>Template:Cite journal</ref>
The naturally occurring enantiomer of RNA is D-RNA composed of D-ribonucleotides. All chirality centers are located in the D-ribose. By the use of L-ribose or rather L-ribonucleotides, L-RNA can be synthesized. L-RNA is much more stable against degradation by RNase.<ref name="pmid25236655">Template:Cite journal</ref>
Like other structured biopolymers such as proteins, one can define topology of a folded RNA molecule. This is often done based on arrangement of intra-chain contacts within a folded RNA, termed as circuit topology.
Chemical modificationsEdit
RNA is transcribed with only four bases (adenine, cytosine, guanine and uracil),<ref>Template:Cite book</ref> but these bases and attached sugars can be modified in numerous ways as the RNAs mature. Pseudouridine (Ψ), in which the linkage between uracil and ribose is changed from a C–N bond to a C–C bond, and ribothymidine (T) are found in various places (the most notable ones being in the TΨC loop of tRNA).<ref>Template:Cite journal</ref> Another notable modified base is hypoxanthine, a deaminated adenine base whose nucleoside is called inosine (I). Inosine plays a key role in the wobble hypothesis of the genetic code.<ref>Template:Cite journal</ref>
There are more than 100 other naturally occurring modified nucleosides.<ref>Template:Cite journal</ref> The greatest structural diversity of modifications can be found in tRNA,<ref>Template:Cite book</ref> while pseudouridine and nucleosides with 2'-O-methylribose often present in rRNA are the most common.<ref>Template:Cite journal</ref> The specific roles of many of these modifications in RNA are not fully understood. However, it is notable that, in ribosomal RNA, many of the post-transcriptional modifications occur in highly functional regions, such as the peptidyl transferase center<ref>Template:Cite journal</ref> and the subunit interface, implying that they are important for normal function.<ref>Template:Cite journal</ref>
Types of RNAEdit
Messenger RNA (mRNA) is the type of RNA that carries information from DNA to the ribosome, the sites of protein synthesis (translation) in the cell cytoplasm. The coding sequence of the mRNA determines the amino acid sequence in the protein that is produced.<ref name=The_Cell/> However, many RNAs do not code for protein (about 97% of the transcriptional output is non-protein-coding in eukaryotes<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journalTemplate:Dead linkTemplate:Cbignore</ref>).
These so-called non-coding RNAs ("ncRNA") can be encoded by their own genes (RNA genes), but can also derive from mRNA introns.<ref name=transcriptome/> The most prominent examples of non-coding RNAs are transfer RNA (tRNA) and ribosomal RNA (rRNA), both of which are involved in the process of translation.<ref name=Biochemistry>Template:Cite book</ref> There are also non-coding RNAs involved in gene regulation, RNA processing and other roles. Certain RNAs are able to catalyse chemical reactions such as cutting and ligating other RNA molecules,<ref>Template:Cite journal</ref> and the catalysis of peptide bond formation in the ribosome;<ref name=ribosome_activity/> these are known as ribozymes.
According to the length of RNA chain, RNA includes small RNA and long RNA.<ref name="Noncoding RNA">Template:Cite journal</ref> Usually, small RNAs are shorter than 200 nt in length, and long RNAs are greater than 200 nt long.<ref name="lncRNA">Template:Cite journalTemplate:Dead link</ref> Long RNAs, also called large RNAs, mainly include long non-coding RNA (lncRNA) and mRNA. Small RNAs mainly include 5.8S ribosomal RNA (rRNA), 5S rRNA, transfer RNA (tRNA), microRNA (miRNA), small interfering RNA (siRNA), small nucleolar RNA (snoRNAs), Piwi-interacting RNA (piRNA), tRNA-derived small RNA (tsRNA)<ref name="tsRNA">Template:Cite journal</ref> and small rDNA-derived RNA (srRNA).<ref name="srRNA">Template:Cite journal</ref> There are certain exceptions as in the case of the 5S rRNA of the members of the genus Halococcus (Archaea), which have an insertion, thus increasing its size.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
RNAs involved in protein synthesisEdit
Messenger RNA (mRNA) carries information about a protein sequence to the ribosomes, the protein synthesis factories in the cell. It is coded so that every three nucleotides (a codon) corresponds to one amino acid. In eukaryotic cells, once precursor mRNA (pre-mRNA) has been transcribed from DNA, it is processed to mature mRNA. This removes its introns—non-coding sections of the pre-mRNA. The mRNA is then exported from the nucleus to the cytoplasm, where it is bound to ribosomes and translated into its corresponding protein form with the help of tRNA. In prokaryotic cells, which do not have nucleus and cytoplasm compartments, mRNA can bind to ribosomes while it is being transcribed from DNA. After a certain amount of time, the message degrades into its component nucleotides with the assistance of ribonucleases.<ref name=The_Cell/>
Transfer RNA (tRNA) is a small RNA chain of about 80 nucleotides that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. It has sites for amino acid attachment and an anticodon region for codon recognition that binds to a specific sequence on the messenger RNA chain through hydrogen bonding.<ref name=transcriptome/>
Ribosomal RNA (rRNA) is the catalytic component of the ribosomes. The rRNA is the component of the ribosome that hosts translation. Eukaryotic ribosomes contain four different rRNA molecules: 18S, 5.8S, 28S and 5S rRNA. Three of the rRNA molecules are synthesized in the nucleolus, and one is synthesized elsewhere. In the cytoplasm, ribosomal RNA and protein combine to form a nucleoprotein called a ribosome. The ribosome binds mRNA and carries out protein synthesis. Several ribosomes may be attached to a single mRNA at any time.<ref name=The_Cell>Template:Cite book</ref> Nearly all the RNA found in a typical eukaryotic cell is rRNA.
Transfer-messenger RNA (tmRNA) is found in many bacteria and plastids. It tags proteins encoded by mRNAs that lack stop codons for degradation and prevents the ribosome from stalling.<ref>Template:Cite journal</ref>
Regulatory RNAEdit
The earliest known regulators of gene expression were proteins known as repressors and activators – regulators with specific short binding sites within enhancer regions near the genes to be regulated.<ref>Template:Cite journal</ref> Later studies have shown that RNAs also regulate genes. There are several kinds of RNA-dependent processes in eukaryotes regulating the expression of genes at various points, such as RNA interference repressing genes post-transcriptionally, long non-coding RNAs shutting down blocks of chromatin epigenetically, and enhancer RNAs inducing increased gene expression.<ref name="Morris-2014">Template:Cite journal</ref> Bacteria and archaea have also been shown to use regulatory RNA systems such as bacterial small RNAs and CRISPR.<ref name="Gottesman-2005">Template:Cite journal</ref> Fire and Mello were awarded the 2006 Nobel Prize in Physiology or Medicine for discovering microRNAs (miRNAs), specific short RNA molecules that can base-pair with mRNAs.<ref name="Nobel Prize-2006">"The Nobel Prize in Physiology or Medicine 2006". Nobelprize.org. Nobel Media AB 2014. Web. 6 Aug 2018. http://www.nobelprize.org/nobel_prizes/medicine/laureates/2006</ref>
MicroRNA (miRNA) and small interfering RNA (siRNA)Edit
Post-transcriptional expression levels of many genes can be controlled by RNA interference, in which miRNAs, specific short RNA molecules, pair with mRNA regions and target them for degradation.<ref>Template:Cite journal</ref> This antisense-based process involves steps that first process the RNA so that it can base-pair with a region of its target mRNAs. Once the base pairing occurs, other proteins direct the mRNA to be destroyed by nucleases.<ref name="Morris-2014" />
Long non-coding RNAsEdit
Next to be linked to regulation were Xist and other long noncoding RNAs associated with X chromosome inactivation. Their roles, at first mysterious, were shown by Jeannie T. Lee and others to be the silencing of blocks of chromatin via recruitment of Polycomb complex so that messenger RNA could not be transcribed from them.<ref>Template:Cite journal</ref> Additional lncRNAs, currently defined as RNAs of more than 200 base pairs that do not appear to have coding potential,<ref name="Rinn-2012">Template:Cite journal</ref> have been found associated with regulation of stem cell pluripotency and cell division.<ref name="Rinn-2012" />
Enhancer RNAsEdit
The third major group of regulatory RNAs is called enhancer RNAs.<ref name="Rinn-2012" /> It is not clear at present whether they are a unique category of RNAs of various lengths or constitute a distinct subset of lncRNAs. In any case, they are transcribed from enhancers, which are known regulatory sites in the DNA near genes they regulate.<ref name="Rinn-2012" /><ref>Template:Cite journal</ref> They up-regulate the transcription of the gene(s) under control of the enhancer from which they are transcribed.<ref name="Rinn-2012" /><ref>Template:Cite journal</ref>
Small RNA in prokaryotesEdit
Small RNAEdit
At first, regulatory RNA was thought to be a eukaryotic phenomenon, a part of the explanation for why so much more transcription in higher organisms was seen than had been predicted. But as soon as researchers began to look for possible RNA regulators in bacteria, they turned up there as well, termed as small RNA (sRNA).<ref>EGH Wagner, P Romby. (2015). "Small RNAs in bacteria and archaea: who they are, what they do, and how they do it". Advances in genetics (Vol. 90, pp. 133–208).</ref><ref name="Gottesman-2005" /> Currently, the ubiquitous nature of systems of RNA regulation of genes has been discussed as support for the RNA World theory.<ref name="Morris-2014" /><ref>J.W. Nelson, R.R. Breaker (2017) "The lost language of the RNA World."Sci. Signal.10, eaam8812 1–11.</ref> There are indications that the enterobacterial sRNAs are involved in various cellular processes and seem to have significant role in stress responses such as membrane stress, starvation stress, phosphosugar stress and DNA damage. Also, it has been suggested that sRNAs have been evolved to have important role in stress responses because of their kinetic properties that allow for rapid response and stabilisation of the physiological state.<ref name="University of Utah-2015" /> Bacterial small RNAs generally act via antisense pairing with mRNA to down-regulate its translation, either by affecting stability or affecting cis-binding ability.<ref name="Morris-2014" /> Riboswitches have also been discovered. They are cis-acting regulatory RNA sequences acting allosterically. They change shape when they bind metabolites so that they gain or lose the ability to bind chromatin to regulate expression of genes.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
CRISPR RNAEdit
Archaea also have systems of regulatory RNA.<ref>Template:Cite journal</ref> The CRISPR system, recently being used to edit DNA in situ, acts via regulatory RNAs in archaea and bacteria to provide protection against virus invaders.<ref name="Morris-2014" /><ref>Template:Cite journal</ref>
RNA synthesis and processingEdit
SynthesisEdit
Synthesis of RNA typically occurs in the cell nucleus and is usually catalyzed by an enzyme—RNA polymerase—using DNA as a template, a process known as transcription. Initiation of transcription begins with the binding of the enzyme to a promoter sequence in the DNA (usually found "upstream" of a gene). The DNA double helix is unwound by the helicase activity of the enzyme. The enzyme then progresses along the template strand in the 3’ to 5’ direction, synthesizing a complementary RNA molecule with elongation occurring in the 5’ to 3’ direction. The DNA sequence also dictates where termination of RNA synthesis will occur.<ref>Template:Cite journal</ref>
Primary transcript RNAs are often modified by enzymes after transcription. For example, a poly(A) tail and a 5' cap are added to eukaryotic pre-mRNA and introns are removed by the spliceosome.
There are also a number of RNA-dependent RNA polymerases that use RNA as their template for synthesis of a new strand of RNA. For instance, a number of RNA viruses (such as poliovirus) use this type of enzyme to replicate their genetic material.<ref>Template:Cite journal</ref> Also, RNA-dependent RNA polymerase is part of the RNA interference pathway in many organisms.<ref>Template:Cite journal</ref>
RNA processingEdit
Many RNAs are involved in modifying other RNAs. Introns are spliced out of pre-mRNA by spliceosomes, which contain several small nuclear RNAs (snRNA),<ref name=Biochemistry/> or the introns can be ribozymes that are spliced by themselves.<ref>Template:Cite journal</ref> RNA can also be altered by having its nucleotides modified to nucleotides other than A, C, G and U. In eukaryotes, modifications of RNA nucleotides are in general directed by small nucleolar RNAs (snoRNA; 60–300 nt),<ref name=transcriptome>Template:Cite book</ref> found in the nucleolus and cajal bodies. snoRNAs associate with enzymes and guide them to a spot on an RNA by basepairing to that RNA. These enzymes then perform the nucleotide modification. rRNAs and tRNAs are extensively modified, but snRNAs and mRNAs can also be the target of base modification.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> RNA can also be methylated.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
RNA in geneticsEdit
RNA genomesEdit
Like DNA, RNA can carry genetic information. RNA viruses have genomes composed of RNA that encodes a number of proteins. The viral genome is replicated by some of those proteins, while other proteins protect the genome as the virus particle moves to a new host cell. Viroids are another group of pathogens, but they consist only of RNA, do not encode any protein and are replicated by a host plant cell's polymerase.<ref>Template:Cite journal</ref>
Reverse transcriptionEdit
Reverse transcribing viruses replicate their genomes by reverse transcribing DNA copies from their RNA; these DNA copies are then transcribed to new RNA. Retrotransposons also spread by copying DNA and RNA from one another,<ref>Template:Cite journal</ref> and telomerase contains an RNA that is used as template for building the ends of eukaryotic chromosomes.<ref>Template:Cite journal</ref>
Double-stranded RNAEdit
Double-stranded RNA (dsRNA) is RNA with two complementary strands, similar to the DNA found in all cells, but with the replacement of thymine by uracil and the adding of one oxygen atom. dsRNA forms the genetic material of some viruses (double-stranded RNA viruses). Double-stranded RNA, such as viral RNA or siRNA, can trigger RNA interference in eukaryotes, as well as interferon response in vertebrates.<ref>Template:Cite journal </ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> In eukaryotes, double-stranded RNA (dsRNA) plays a role in the activation of the innate immune system against viral infections.<ref>Template:Cite journal</ref>
Circular RNAEdit
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In the late 1970s, it was shown that there is a single stranded covalently closed, i.e. circular form of RNA expressed throughout the animal and plant kingdom (see circRNA).<ref>Template:Cite journal</ref> circRNAs are thought to arise via a "back-splice" reaction where the spliceosome joins a upstream 3' acceptor to a downstream 5' donor splice site. So far the function of circRNAs is largely unknown, although for few examples a microRNA sponging activity has been demonstrated.
Key discoveries in RNA biologyEdit
Research on RNA has led to many important biological discoveries and numerous Nobel Prizes. Nucleic acids were discovered in 1868 by Friedrich Miescher, who called the material 'nuclein' since it was found in the nucleus.<ref>Template:Cite journal</ref> It was later discovered that prokaryotic cells, which do not have a nucleus, also contain nucleic acids. The role of RNA in protein synthesis was suspected already in 1939.<ref>Template:Cite journal</ref> Severo Ochoa won the 1959 Nobel Prize in Medicine (shared with Arthur Kornberg) after he discovered an enzyme that can synthesize RNA in the laboratory.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> However, the enzyme discovered by Ochoa (polynucleotide phosphorylase) was later shown to be responsible for RNA degradation, not RNA synthesis. In 1956 Alex Rich and David Davies hybridized two separate strands of RNA to form the first crystal of RNA whose structure could be determined by X-ray crystallography.<ref>Template:Cite journal</ref>
The sequence of the 77 nucleotides of a yeast tRNA was found by Robert W. Holley in 1965,<ref>Template:Cite journal</ref> winning Holley the 1968 Nobel Prize in Medicine (shared with Har Gobind Khorana and Marshall Nirenberg).
In the early 1970s, retroviruses and reverse transcriptase were discovered, showing for the first time that enzymes could copy RNA into DNA (the opposite of the usual route for transmission of genetic information). For this work, David Baltimore, Renato Dulbecco and Howard Temin were awarded a Nobel Prize in 1975. In 1976, Walter Fiers and his team determined the first complete nucleotide sequence of an RNA virus genome, that of bacteriophage MS2.<ref>Template:Cite journal</ref>
In 1977, introns and RNA splicing were discovered in both mammalian viruses and in cellular genes, resulting in a 1993 Nobel to Philip Sharp and Richard Roberts. Catalytic RNA molecules (ribozymes) were discovered in the early 1980s, leading to a 1989 Nobel award to Thomas Cech and Sidney Altman. In 1990, it was found in Petunia that introduced genes can silence similar genes of the plant's own, now known to be a result of RNA interference.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
At about the same time, 22 nt long RNAs, now called microRNAs, were found to have a role in the development of C. elegans.<ref>Template:Cite journal</ref> Studies on RNA interference earned a Nobel Prize for Andrew Fire and Craig Mello in 2006, and another Nobel for studies on the transcription of RNA to Roger Kornberg in the same year. The discovery of gene regulatory RNAs has led to attempts to develop drugs made of RNA, such as siRNA, to silence genes.<ref>Template:Cite journal</ref> Adding to the Nobel prizes for research on RNA, in 2009 it was awarded for the elucidation of the atomic structure of the ribosome to Venki Ramakrishnan, Thomas A. Steitz, and Ada Yonath. In 2023 the Nobel Prize in Physiology or Medicine was awarded to Katalin Karikó and Drew Weissman for their discoveries concerning modified nucleosides that enabled the development of effective mRNA vaccines against COVID-19.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite news</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Relevance for prebiotic chemistry and abiogenesisEdit
In 1968, Carl Woese hypothesized that RNA might be catalytic and suggested that the earliest forms of life (self-replicating molecules) could have relied on RNA both to carry genetic information and to catalyze biochemical reactions—an RNA world.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite journal</ref> In May 2022, scientists discovered that RNA can form spontaneously on prebiotic basalt lava glass, presumed to have been abundant on the early Earth.<ref name="AST-20220519">Template:Cite journal</ref><ref name="PO-20220603">Template:Cite news</ref>
In March 2015, DNA and RNA nucleobases, including uracil, cytosine and thymine, were reportedly formed in the laboratory under outer space conditions, using starter chemicals such as pyrimidine, an organic compound commonly found in meteorites. Pyrimidine, like polycyclic aromatic hydrocarbons (PAHs), is one of the most carbon-rich compounds found in the universe and may have been formed in red giants or in interstellar dust and gas clouds.<ref name="NASA-20150303">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In July 2022, astronomers reported massive amounts of prebiotic molecules, including possible RNA precursors, in the galactic center of the Milky Way Galaxy.<ref name="SA-20220708">Template:Cite news</ref><ref name="FASS-20220708">Template:Cite journal</ref>
Medical applicationsEdit
RNA, initially deemed unsuitable for therapeutics due to its short half-life, has been made useful through advances in stabilization. Therapeutic applications arise as RNA folds into complex conformations and binds proteins, nucleic acids, and small molecules to form catalytic centers.<ref>Template:Cite journal</ref> RNA-based vaccines are thought to be easier to produce than traditional vaccines derived from killed or altered pathogens, because it can take months or years to grow and study a pathogen and determine which molecular parts to extract, inactivate, and use in a vaccine. Small molecules with conventional therapeutic properties can target RNA and DNA structures, thereby treating novel diseases. However, research is scarce on small molecules targeting RNA and approved drugs for human illness. Ribavirin, branaplam, and ataluren are currently available medications that stabilize double-stranded RNA structures and control splicing in a variety of disorders.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Protein-coding mRNAs have emerged as new therapeutic candidates, with RNA replacement being particularly beneficial for brief but torrential protein expression.<ref name="dx.doi.org">Template:Cite journal</ref> In vitro transcribed mRNAs (IVT-mRNA) have been used to deliver proteins for bone regeneration, pluripotency, and heart function in animal models.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> SiRNAs, short RNA molecules, play a crucial role in innate defense against viruses and chromatin structure. They can be artificially introduced to silence specific genes, making them valuable for gene function studies, therapeutic target validation, and drug development.<ref name="dx.doi.org" />
mRNA vaccines have emerged as an important new class of vaccines, using mRNA to manufacture proteins which provoke an immune response. Their first successful large-scale application came in the form of COVID-19 vaccines during the COVID-19 pandemic.
See alsoEdit
Template:Portal Template:Div col
- Biomolecular structure
- RNA virus
- DNA
- History of RNA Biology
- List of RNA Biologists
- RNA Society
- Macromolecule
- RNA-based evolution
- Aptamer
- RNA origami
- Transcriptome
- RNA world hypothesis
ReferencesEdit
External linksEdit
Template:Sister project Template:Sister project
- RNA World website Link collection (structures, sequences, tools, journals)
- Nucleic Acid Database Images of DNA, RNA, and complexes.
- Anna Marie Pyle's Seminar: RNA Structure, Function, and Recognition Template:Webarchive
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