Therapeutic potential of micrornas

microRNAs (or miRNAs) are short noncoding RNAs acting as one of the most important regulatory molecules in the cellular environment. They exert their function mainly through posttranscriptional silencing of their target mRNAs in the cytoplasm. The most common methods of microRNA-caused gene downregulation are translational repression and mRNA degradation. microRNAs are usually 18-24 nt long and canonically recognize their targets by perfect Watson- Crick pairing with their 6-8 nt long “seed” region at the 5’ end. Due to their specific way of target binding, they are able to regulate genes involved in virtually all cellular pathways and processes. Therefore, it is not surprising that their disbalance can contribute to, or induce, significant changes in normal cell homeostasis, and consequently developmental problems or disease emergence. This great variety of targets and wide impact on the cellular networks give these small molecules an enormous potential to be used in diagnostic and therapeutic purposes. In this chapter, we will focus on microRNAs biogenesis and function, with specific emphasis on their dysregulation in human diseases and potential therapeutic application, and summarize the most recent advances in the field.