BRIEF ON LONG NON-CODING RNA
By: Dr. Husna Nugrahapraja
The discovery of DNA molecules in 1870 through research conducted by Frederich Miescher related to the chemical composition of the cell nucleus and then perfected by Watson-Crick (1953) has opened an understanding of the central dogma of molecular biology. The central dogma in molecular biology explains how a DNA becomes RNA, and RNA becomes a protein. However, the development of genomic technology suggests that molecular mechanisms are not only determined from the resulting proteins but are also influenced by other RNA molecules. RNA molecules can be either RNA coding and non-coding RNA, determined by their ability to produce a protein in the cell.
Eukaryotic genomes have very high complexity and can transcribe varied RNA molecules in length, abundance and potential to produce proteins. These large-abundance RNA molecules are often inserted or overlapped in the genome (Ponting et al., 2009). As a result, most of us only recognize some of the RNA molecules involved and play a role in regulating gene expression in living organisms, including messenger RNA (mRNA), transfer of RNA (tRNA), ribosomal RNA (rRNA), small nuclear RNA (snRNA ), micro RNA (miRNA), and small interfering RNA (siRNA). However, with the development of bioinformatics-based sequencing technology through the cDNA / EST in silico approach, it has defined a new RNA molecule that acts as a regulatory molecule in gene expression, known as long non-coding RNA (lncRNA) (Li et al., 2014 ). This technology is able to identify about 10,000 lncRNAs in humans (Derrien et al., 2012), 23,324 lncRNAs in Medicago truncatula (Wang et al., 2015), 1565 lncRNA candidates in tomatoes (Wang et al., 2015), 20,163 lncRNAs in maize (Li et al., 2014) and 2,224 lncRNAs in rice (Zhang et al., 2013). In the beginning, lncRNA was mentioned as a black matter in the cell due to the unknown function. Further studies suggesting lncRNA is involved in many biological processes, such as cell cycle, transcription, post-transcription, translation and post-translation. lncRNA can be distinguished from other non-coding RNAs because encode more than 200 nucleotides in length and has short open reading frame (ORF). Compared with small RNA and protein-coding genes, lncRNA sequences are less conserved. In plants, lncRNAs have been associated with several plant physiological mechanisms, such as plant disease, biotic and abiotic stresses. lncRNAs in plants have been found to work in the formation of nodules, inflorescences, phosphate-taking homeostases, disease resistance, environmental stress and growth by regulating the expression of genes and proteins in cells (Zhang et al., 2013; Liu et al., 2015).
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