Molecular Evolution of miR-34 Gene Family

miR-34 gene can regulate early development of mammalian. Using bioinformatics analysis of sequenced metazoan genomes, 54 miR-34 genes of 33 different animal species were found. Eighteen miR-34 genes were identified in the first time, suggesting miRNA are highly conservative and widespread in Eukaryotes. Of these mir-34 gene homologues identified in metazoan, 80% locate in the intergenic region, the others are in the intron or 3'UTR of protein-coding gene. miR-34 gene is conserved in various animals, and the mature sequences and precursors of mir-34 gene in metazoan analyzed share 68% and 38.89% sequence identity, respectively. However there is only a mir-34 gene in invertebrate and three mir-34 genes, mir-34a, mir-34b and mir-34c are present in almost all vertebrate. The phylogenetic analysis reveals that the miR-34 gene family of vertebrate originated from local and tandem duplications followed by mutation of individual base after divergence from invertebrate.