The basis of eukaryotic complexity is an intricate genetic architecture where parallel systems are involved in tuning gene expression, via RNA-DNA, RNA-RNA and RNA-protein and DNA-protein interactions. In higher organisms, about 97% of the transcriptional output is represented by non-coding RNA (ncRNA) encompassing not only rRNA, tRNA, introns, 5’ and 3’-untranslated regions, transposable elements and intergenic regions, but also a large rapidly emerging family, named microRNAs. MicroRNAs are short 20-22 nucleotide RNA molecules that have been shown to regulate the expression of other genes in a variety of eukaryotic systems. MicroRNAs are formed from larger transcripts that fold to produce hairpin structures and serve as substrates for the cytoplasmic Dicer, a member of the RNase III enzyme family. A recent analysis of the genomic location of human microRNA genes suggested that 50% of microRNA genes are located in cancer-associated genomic regions or in fragile sites. This review focuses on the possible implications of microRNAs in post-transcriptional gene regulation in mammalian diseases, with particular focus on cancer. We argue that developing mouse models for deleted and/or overexpressed microRNAs will be of invaluable interest to decipher the regulatory networks where microRNAs are involved.
Recommended CitationSevignani, Cinzia; Calin, George A.; Siracusa, Linda D.; and Croce, Carlo M., "Mammalian microRNAs: A small world for fine-tuning gene expression" (2005). Department of Microbiology and Immunology Faculty Papers. Paper 1.