title: Structural aspects of microRNA biogenesis.
abstract: One of the biggest surprises at the beginning of the 'post-genome era' was the discovery of numerous genes encoding microRNAs. They were found in genomes of such diverse organisms as Caenorhabditis elegans, Drosophila melanogaster, Arabidopsis thaliana, and Homo sapiens which implies their important role in multicellular life evolution. The number of microRNA genes is estimated to be nearly 1% of that of protein-coding genes. Their products, tiny RNAs, are thought to regulate gene expression during development, organogenesis, and very likely during many other processes, by hybridizing to their target mRNAs. The cellular functions of mRNAs that are regulated by microRNAs are only beginning to be revealed, and details of this regulation mechanism are still poorly understood. In this article we discuss the possible mechanisms of microRNA biogenesis with special emphasis on their structural aspects. We have focused on the factors and effects that may be responsible for the existing length differences between different microRNAs, and for the observed length heterogeneity within some individual microRNA species.
authors.affiliation: Laboratory of Cancer Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14., 61-704 Poznan, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Krol
authors.forename: Wlodzimierz J
authors.initials: WJ
authors.lastname: Krzyzosiak
mesh_terms: D000818:Animals; D006801:Humans; D035683:MicroRNAs / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D020836:Protein Structure, Quaternary; D012322:RNA Precursors / Q000378:metabolism; D043244:Ribonuclease III / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity / Q000502:physiology
chemical_list: D035683:MicroRNAs; D012322:RNA Precursors; D043244:Ribonuclease III