Measuring the amount of naturally-occurring miRNAs in tissues of
different physiological and pathological conditions is an
important first step to investigate the functions of miRNAs.
Applied Biosystems scientists examined the profiles of 345 human
miRNAs in 40 normal tissues using TaqMan MicroRNA Assays. These
profiles provide a baseline against which miRNA profiles in
tissues can be compared.  Normalizing RNA Input  The expression
of 345 human miRNAs was quantitated in 40 normal human tissues
including brain, muscle, circulatory, respiratory, lymphoid,
gastrointestinal, urinary, reproductive, and endocrine systems.
Four human miRNAs (miR-30e, miR-92, miR-92N, and miR-423) were
identified as the least variable across this study. The average
value of these miRNAs was used to normalize the RNA input
between tissues. Sample input was also normalized by
quantitating small nuclear RNAs using the TaqMan MicroRNA Assay
Controls, and the key patterns of the hierarchical clustering of
both miRNAs and tissues was very