PureLink™ miRNA Isolation Kit From Invitrogen

MicroRNAs (miRNAs) are endogenous small noncoding RNAs (20 - 23 nucleotides) that negatively regulate posttranscriptional gene expression by base pairing to the 3' untranslated region of target messenger RNAs. miRNAs have been identified in plants and animals and have been evolutionarily conserved across many species. Several lines of evidence indicate that miRNAs play a vital role in regulating various physiological and pathological pathways such as cell differentiation, cell proliferation, and tumorigenesis. These studies also postulate miRNAs could potentially provide valuable molecular targets for cancer drug discovery.

The efficient isolation and purification of miRNAs is the foundation of subsequent functional analysis of miRNAs. Our laboratory was interested in studying the miRNAs induced or repressed in response to growth factors like EGF in lung cancer cells. A549 cells were treated with 100 ng/ml EGF for 48 hours and then cells were harvested for isolating miRNA. We used the PureLink™ miRNA Isolation Kit from Invitrogen for isolating miRNA. The kit requires approx 1x106 cells for miRNA isolation; therefore, 2 wells of a 6-well plate provide more than enough cells from which to isolate miRNA.

The kit contains an elaborate technical manual with detailed procedures for cell lysis and miRNA isolation and characterization. The procedure for miRNA isolation is very easy and takes less than 2 hours. The miRNA obtained is high quality and can be directly used for Northern blotting, real-time PCR or miRNA microarrays. The best part of the kit is that it is compatible with the BLOCK-iT™ Dicer siRNA Kit from Invitrogen and can be used to purify diced siRNA. Since we use the Dicer kit from Invitrogen in our laboratory, the miRNA isolation kit is a great fit for both miRNA and siRNA purification. The kit has a good shelf life and all the components are stored at room temperature. The kit is very reasonably priced and is cheaper than miRNA isolation kits from other companies. The technical support from the company is excellent.

After isolation, miRNAs are run on a 15% gel and visualized with ethidium bromide after electrophoresis. It would be great if the company could include a positive control in the kit, for example, an miRNA sample isolated from a cell line (or a tissue) that would make it easier to identify the correct bands. I would like to mention here that miRNA research is a relatively new field and there are not many companies providing reagents to study miRNAs. With that point in mind, I would unhesitatingly recommend the Invitrogen PureLink™ miRNA kit as a great resource for all scientists in the field of miRNA biology.