Subtopic 5.3: MicroRNAs Assay
MicroRNAs assays are used to know the non-coding RNAs (17 to 25 nucleotides) which target messenger RNAs (mRNAs) and decayed the mRNAs or downregulated at the level of translation into protein. Almost, 60% of human protein coding genes are controlled by miRNAs and these miRNAs are epigenetically regulated. About 50% of miRNA genes are related with CpG islands, which may be repressed by epigenetic methylation. Other miRNAs are epigenetically controlled by either histone modifications or by DNA methylation. The expression of microRNAs are quantified by RT-PCR followed by quantitative PCR (qPCR). Then, miRNAs are hybridized to microarrays, slides or chips with probes to hundreds or thousands of miRNA targets. The microRNAs can be both invented and profiled by sequencing methods (microRNA sequencing) (Figure 4).