In Silico Determination of MicroRNA Distribution in Chimpanzees (Pan troglodytes) and Humans (Homo sapiens) and Identification of de novo MicroRNAs Implicated in Hominid Uplift Through Segmental Duplication

Abstract

MicroRNAs (miRNA) are ~21 nucleotide-long gene regulators whose action may be via translational repression or protein degradation. Segmental duplications have been found to be one of the driving forces in acquiring new genes. Both microRNA and segmental duplication have been speculated to have played a significant role in evolution, particularly in the divergence of human (Homo sapiens) from the chimpanzee (Pan troglodytes). The goal of the study is to determine the distribution of miRNAs in humans and in chimpanzees, and propose hypotheses on its significance to the occurrence of segmental duplications. Sequences acquired from miRBASE were subjected to BL AT to identify miRNAs located in regions of segmental duplication (SD regions) and BLAST to determine which of these miRNA are also located in non-SD regions. ClustalW was utilized to determine which human and chimp miRNAs were homologous. BLAST was then used to determine whether the non-homologous human miRNA are homologous to any other part of the chimpanzee genome. It was found that all 695 human miRNAs are found exclusively in SD regions, and that 67 are de novo miRNAs. Thirteen were found to be homologs of chimpanzee miRNA, and 11 were possibly derived from non-miRNA regions in chimp — of these, 6 were found to be located in SD regions of the chimpanzee genome. This demonstrates that the evolution of miRNA occurs within regions of segmental duplication. It is suggested that miRNA duplicates provide raw genetic material, which allows more exposure to mutations that could necessitate diversification, and possibly evolution, through sub- and neofunctionalization.