There is a growing recognition that noncoding RNAs (ncRNA) play an important role in the regulation of gene expression. A class of small (19-22 nt) ncRNAs, known as microRNAs (miRNAs), have received a great deal of attention lately because of their ability to repress gene expression through a unique posttranscriptional 3'-untranslated region (UTR) mechanism. MiRNAs have been shown to be involved in a range of biological processes, being involved in most biological processes examined to date. These molecules are processed by Dicer, an enzyme responsible for the maturation of microRNA. Several studies have tried to investigate the actual role of miRNAs in physiological processes through functional studies (knockout) in vivo and in vitro. However, these molecules act together in various signaling pathways, which makes complex the understanding of how miRNAs act in muscle adaptation processes. Thus, to better understand the role of miRNAs in controlling muscle mass, the goal of this project is to investigate the effect of global depletion of microRNAs during hypertrophy processes, atrophy and aging using a Knockout model-specific muscle of Dicer. The Sham (n = 10 mice in the vehicle application) and knockout (tamoxifen induction of application for deletion of Dicer) animals will be divided into the following experimental groups: animals subjected to the hypertrophic process (removal of synergist muscles, n = 10), animals undergoing muscular atrophy (suspending members, n = 10) and aged animals (24-26 months, n = 10). At the end of experiment the animals will be sacrificed, the muscles (soleus and plantaris) removed and subsequently subjected to immunostaining and molecular analysis. The data will be submitted to appropriate statistical analysis.
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