Introduction
RNA (ribonucleic acid) is a type of nucleic acid that plays a crucial role in gene expression and protein synthesis in living organisms. RNA is similar in structure to DNA (deoxyribonucleic acid), but it has some important differences. One key difference is that RNA is usually single-stranded, while DNA is double-stranded.
Overview
- rRNA
- ribosomal
- rRNA + protein = ribosome
- most abundant of all RNA types
- clinical importance
- shiga- and verotoxins bind to 28S rRNA
- inhibit eukaryotic protein synthesis
- tRNA
- transfer
- covalently attached to amino acids
- provides link between genetic code and a particular amino acid
- mRNA
- messenger
- carries DNA message from chromosome to translation by ribosome
- hnRNA or pre-mRNA
- heteronuclear
- present only in eukaryotes
- mRNA transcript prior to splicing
- contains introns and exons
- snRNA
- small nuclear
- present only in eukaryotes
- functions in splicing of mRNA in the nucleus
- Ribozymes
- present in eukaryotes and prokaryotes
- have intrinsic enzymatic activity
- miRNA
- micro
- ↓ translation by binding to 3′-UTR of target mRNA
- double-stranded RNA signals for degradation
- uses Dicer and RISC enzymes in processing
- often coded for in intron segments
- RNAi is a synthetic lab technique that takes advantage of miRNA pathway
- see Biochemical Model Systems topic
Symptoms
RNA types themselves do not cause any specific symptoms as they are essential molecules involved in various cellular processes. However, dysregulation or mutations in RNA can lead to a variety of symptoms and diseases.
For example, mutations in mRNA can cause genetic diseases such as cystic fibrosis, sickle cell anemia, and Huntington’s disease. These mutations can affect the production or function of proteins, leading to the development of specific symptoms and health problems.
Similarly, alterations in miRNA and siRNA levels or function have been linked to various diseases such as cancer, heart disease, and neurological disorders. Dysregulation of snRNA can cause diseases such as spinal muscular atrophy and lupus.
Studies
- mRNA studies: Researchers have used various techniques such as transcriptomics, ribosome profiling, and CRISPR-based approaches to study mRNA expression and function in different cell types and disease states. These studies have provided insights into the mechanisms of gene expression, protein synthesis, and disease pathogenesis.
- tRNA studies: Studies have shown that tRNA modifications and mutations can affect translation accuracy and efficiency, leading to a range of diseases such as cancer, neurodegeneration, and mitochondrial disorders.
- rRNA studies: Researchers have used cryo-electron microscopy and other structural biology techniques to study the structure and function of ribosomes and rRNA. These studies have provided insights into the mechanisms of protein synthesis and ribosome-targeting antibiotics.
- snRNA studies: Studies have shown that mutations in snRNAs or splicing factors can cause splicing defects, leading to various genetic diseases such as spinal muscular atrophy and retinitis pigmentosa.
- miRNA and siRNA studies: Researchers have used genomics, bioinformatics, and functional assays to study the roles of miRNAs and siRNAs in gene regulation and disease. These studies have identified numerous miRNA and siRNA targets and provided insights into the mechanisms of RNA interference and gene silencing.
Complications
- RNA-based diseases: As mentioned earlier, mutations in RNA can cause genetic diseases such as cystic fibrosis, sickle cell anemia, and Huntington’s disease. Alterations in miRNA and siRNA levels or function have also been linked to various diseases such as cancer, heart disease, and neurological disorders. Dysregulation of snRNA can cause diseases such as spinal muscular atrophy and lupus.
- Viral infections: RNA viruses such as COVID-19, influenza, and HIV use RNA as their genetic material. These viruses can cause a range of symptoms and complications, depending on the type of virus and the affected tissues. For example, COVID-19 can lead to respiratory distress, acute respiratory distress syndrome (ARDS), and multi-organ failure.
- RNA toxicity: Some RNA molecules, such as repeat expansion RNAs, can cause toxicity by sequestering RNA-binding proteins and disrupting cellular function. This can lead to diseases such as myotonic dystrophy and amyotrophic lateral sclerosis (ALS).
- RNA instability: RNA is a relatively unstable molecule and can be easily degraded by RNases. Disruption of RNA stability can lead to defects in gene expression and protein synthesis, resulting in cellular dysfunction and disease.
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