MicroRNAs in viral pathogenesis

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2015MicroRNAs are small non-coding RNAs important in gene regulation. MicroRNAs are able to regulate mRNA translation through base pair complementarity. Cellular microRNAs have been involved in the regulation of nearly all cellular pathways and their deregulation have been associated with several diseases such as cancer. Given the importance of microRNAs to cell homeostasis, it is no surprise that virus evolved to take advantage of this cellular pathway. Virus have been reported to be able to encode and express functional viral microRNAs that target both viral and cellular transcripts. Moreover, inhibition of key proteins from the microRNA pathway was reported, as well as important changes in cellular microRNA pool, upon viral infection. In addition, virus developed multiple mechanisms to avoid being targeted by cellular microRNAs. This complex interaction between host and virus to control the microRNA pathway usually favour viral infection and persistence by either reducing immune detection, avoiding apoptosis, promoting cell growth or promoting lytic or latent infection. This review focus on the relation between virus, host and miRNAs and the related mechanisms that contribute for infection and pathology