Differential Perspectives Between miRNA and lncRNA in Light of Biogenesis and Functions: A Review

The central dogma is suggested that deoxyribonucleic acid is translated into ribonucleic acid (RNA) and then into protein. It is considered that 2–3% of the genomic DNA in a functionally active cell, is transcribed to protein-coding RNA. The presence of noncoding transcripts has been neglected many a time as cellular DNA and transcript noises, however, increasing proof proposes that a very important part of these non-coding transcripts is functionally effective as RNA molecules. The non-coding transcripts of up to 100 bases are known as small non-coding RNA that comprises tRNA, miRNA, snoRNA, piwi-interacting RNA (pi-RNA), etc. Interestingly, rRNA features about 6.9 kb, though these are not considered long-non-coding RNAs. However, RNA molecules that are over 200 bases long (ranging between 0.8 to 10 kb) are known as long non-coding RNA (lncRNA). It does not have open reading frames (with some exceptions), 3`- untranslated regions (3’-UTRs), and these RNAs are devoid of any translation-termination regions. However, these may be capped, spliced, and polyadenylated as RNA molecules and play a major role in factor regulation, neoplastic cell invasion, chromatin granule transforming, and cell differentiation. Downregulation of lncRNA is responsible for numerous diseases in mammals. miRNAs are mature transcripts of 22 nt in length and function as antisense regulators of other RNAs. They play role in post-transcriptional factors and are involved in differentiation, proliferation, immune response, cell growth, and caspase-mediated cell death. Downregulation in miRNA expression has a necessary role in many diseases, together with cancers.