Quantitative RT-PCR Methods for Mature microRNA Expression Analysis

This chapter describes two methods to measure expression of mature miRNA levels using qRT-PCR. The first method uses stem-loop RT primers to produce cDNA for specific miRNAs, a technique that our laboratory has modified to increase the number of miRNAs being reverse transcribed within a single RT reaction from one (as suggested by the manufacturer) to five. The second method uses a modified oligo(dT) technique to reverse transcribe all transcripts within an RNA sample; therefore, target miRNA and normalizing mRNA can be analyzed from the same RT reaction. We examined the level of miRNA-132, a miRNA known to be upregulated in granulosa cells following hCG treatment, using both of these methods. Data were normalized to GAPDH or snU6 and evaluated by ΔΔCt and standard curve analysis. There was no significant difference (P > 0.05) in miRNA-132 expression between the stem-loop and modified oligo(dT) RT methods indicating that both are statistically equivalent. However, from a technical point of view, the modified oligo(dT) method was less time consuming and required only a single RT reaction to reverse transcribe both miRNA and mRNA.