Molecule of the month: miRNA and HIV-1 TAR

A recent publication analyzed MicroRNAs (miRNAs) globallyinhumans [1]. Here, we summarize several key concepts from this article. Apparently during evolution, there were several origins of miRNAs and the authors embarked on a detailed and specific analysis of these events. In fact, the authors analyzed 1,433 extant human miRNAs that originated 15 times during evolution. These steps correspond to the evolutionary progression of the following species: avians, Prototheria platypus, Metatheria opossum/wallaby, Atlantogenata, Laurasiatheria, rodents/rabbits, tupai, lemur/galago, tarsier, marmoset, rhesus monkey, gibbon ape, orangutan, gorilla, chimpanzee, and humans. The rates of origin of miRNAs was greatest (most accelerated) in two periods, during the Atlantogenata-Laurasiatheria transition/origin period and during the monkey-gibbon ape transition/origin period. Across all 15 originations, the extents of expression are lower for the younger miRNAs [1]. It should be noted that the process of miRNA integration, stabilization, and expression in an organism’s transcriptome takes 60 million years. In addition, there is an ongoing process of miRNA expression increase during that time [2]. It is noteworthy that the HIV-1 antecedent viruses may have evolved among the primates during this most recent resurgence of miRNAs.