Small RNA Biogenesis and Role in Gene Expression Regulation - Essay Example

Download file to see previous pages They regulate post-transcriptional modifications from bacteria to mammals and are also implicated in the regulation of critical pathways such as stress response in bacteria, developmental timing, and cell differentiation in plants and metazoans 3, 5.  They also play a role in antiviral defense 5. The small RNA’s are of two types, micro RNA’s (miRNAs) and small interfering RNA’s (siRNAs) 7, and in their effective state they range from 21 to 25 nucleotides 5, 6. Both types of small RNAs are produced from longer RNA precursors with the help of nucleases called DICER in animals and DICER LIKE (DCL) in plants 7. The siRNA and miRNA have different origins. The miRNAs (approximately 21 to 22 nucleotides) are encoded by their own genes 7 and are generated from the non-protein-coding dsRNA region of the hairpin shaped precursors 1, 5. The siRNAs (approximately 21 to 24 nucleotides) are derived from long double-stranded RNAs 1. They are processed from these dsRNA precursors that arise from mRNAs, transposons, viruses, or heterochromatic DNA 5, 7.
They were discovered initially in nematodes in 1993.  They are found in plants and animals and in the viruses that infect them. They play a vital role during gene expression during plant and animal development and it has been postulated that they regulate one-third of human genes 9. The coding sequences of most miRNAs lie in the genome, distinct from the protein-coding sequences, while most of the mammalian miRNA genes lie within the introns of protein-coding genes or in the untranslated regions of protein-coding genes or within the introns or exons of non-coding genes. ...Download file to see next pagesRead More