MicroRNAs (miRNAs) are a class of small noncoding RNAs (typically 19-23 nucleotides) which act by annealing to partially complementary binding sites present on the 3' untranslated regions (UTR) of messenger RNAs (mRNAs) leading to inhibition of protein translation or by inducing mRNA decay. Since their discovery, miRNAs have come to be recognized as master regulators of gene expression in plant and mammals, controlling tissue-specific protein expression. Up to one-third of mammalian mRNAs are susceptible to miRNA-mediated regulation. It has been shown that miRNAs are determinants of the physiology and pathophysiology of the cardiovascular system, and altered expression of muscle- and/or cardiac-specific miRNAs in myocardial tissue is involved in heart development and cardiovascular diseases, including myocardial hypertrophy, heart failure, and fibrosis. The analysis of miRNA expression pattern provides important information, as well as is a starting point to understand miRNA function in different tissues, during development, and in disease. Several techniques can be used for miRNA profiling analysis like high-throughput sequencing, microarrays, and real-time PCR using microfluidic low-density arrays. This chapter describes the complete methodology to perform miRNA profiling using the stem-loop reverse-transcription (RT)-based TaqMan® MicroRNA low-density arrays (TLDA) method. This methodology was used to perform miRNA profiling in the heart of T. cruzi acutely infected mice.
Keywords: Expression profiling; Low-density arrays; MicroRNA; Real-time RT-PCR.