miRNAs as modulators of angiogenesis.

MicroRNAs are highly expressed in endothelial cells, and recent data suggest that they regulate aspects of vascular development and angiogenesis. This study highlights the state of the art in this field and potential therapeutic opportunities. MicroRNAs (miRNAs) represent a family of conserved short (≈22 nt) noncoding single-stranded RNAs that have been identified in plants and animals. They are generated by the sequential processing of the RNA template by the enzymes Drosha and Dicer, and mature miRNAs can regulate the levels of gene expression at the posttranscriptional level. miRNAs participate in a diverse range of regulatory events via regulation of genes involved in the control of processes such as development, differentiation, homeostasis, metabolism, growth, proliferation, and apoptosis. However, rather than functioning as regulatory on-off switches, miRNAs often function to modulate or fine-tune cellular phenotypes. So far, more than 1000 mammalian miRNAs have been identified since the discovery of the first two miRNAs (lin-4 and let-7), and bioinformatics predictions indicate that mammalian miRNAs can regulate ∼30% of all protein-coding genes.