The miR-7 family: an evolutionary conservation and multifunctional miRNA family

microRNAs (miRNAs) are a class of non-coding RNA molecules that regulate biophysiological and biochemical processes by modulating gene expression. miR-7 is widespread and sequence conserved across species. Due to its conserved sequence and the similarity of specific expression sites, the miR-7 family members are of great significance in the study of species evolution. This review focuses on the evolutionary characterization of the miR-7 family and the functional diversity. The miR-7 family is widespread in several species and its mature and precursor sequences are evolutionarily conserved. In invertebrates, miR-7 family members are involved in immune defense, cell development and tissue generation, and metabolic regulation. And in chordates, miR-7 family members can be used as therapeutic targets for diseases, affecting the disease process and drug sensitivity by targeting and regulating multiple genes. miR-7 family members also play important roles in cell development and differentiation and tissue regeneration. Here, we focus on the emerging roles of miR-7 family in these processes by discussing functional differences generated by the old and novel targets, mechanisms identified to mediate or interact with miR-7 family and the most recently unraveled clinical implications of miR-7 family regulatory pathways toward diseases.