miRNAs are small, non-coding RNA molecules utilizing endogenous RNAi mechanisms to control expression of genes. They can be found across species, tissues and organism developmental stages, playing pivotal roles in many biological processes. Every day brings new information about novel miRNA functions. With this ever-expending role of miRNA across biological disciplines, there is a great need to have a good reagent, which can mimic miRNA function, concomitantly allowing for precise control over its expression.
Ambion’s Pre-miR™ miRNA Precursor Molecules are designed to specifically mimic endogenous mature miRNAs. Each Precursor is a chemically modified, synthetic, small, double-stranded RNA molecule, which can inconspicuously slither into the RNA-induced silencing-like complex machinery responsible for biosynthesis of endogenous miRNA in cells, where it is modified into a mature, functional miRNA.
Pre-miR™ miRNA Precursors can be introduced into cells using traditional transfection or electroporation methods. The advantage of using Precursors over the miRNA expression vector systems is that the amount of miRNA Precursor used in transfection is known and directly corresponds to the amount of the final mature miRNA, derived from the Precursor, whereas the amount of miRNA produced from vectors is harder to control.
I use Ambion’s Pre-miR™ miRNA Precursors to transfect HEK cells and determine the effects of particular miRNAs on the expression of genes of interest. Transfection efficiency is very high and the amount of functional miRNA easily controllable. Another nice aspect of Ambion’s system is the availability of positive and negative controls which we include in each experiment. Moreover, the Pre-miR™ Precursor Starter Kit helps to optimize transfection conditions at the beginning of the project. Another positive aspect is that Pre-miR™ miRNA Precursors are ready to go just after the purchase, and do not need to be cut out and pasted into the vectors. The only downside is that eventually they will be used up, while miRNA expression vectors can be purchased once and then amplified indefinitely as needed.
In summary, Pre-miR™ miRNA Precursors are very convenient, highly recommended reagents to study miRNA function, but need to be re-purchased, especially for bigger projects.