Some days ago I was challenging the concept that a reporter need to be a protein. Imagine my surprise in reading the March issue of Nature Methods, where Romanov and colleagues from Attagene Inc, describe a novel method for simultaneously reporting on the activity of a large panel of transcription factors. Here the reporter is a synthethic sequence that isn't translated, but only transcribed, an example of RNA-based reporters. Moreover, the paper breaks the dogma 'one promoter - one reporter' by analyzing activities of multiple TFs with just 'one' reporter sequence.
The trick is that they cloned TFs binding sites in front of a reporter sequence with an enzymatic cleavage site in a separate position for each TF, so that after these constructs are transfected within a cell, digest of the reporter species produced spectrum of DNA fragments that mirrored TF activities profile.
Although CE is limited by a narrow dynamic range, and the assay is challenged by the management of up to 30 sequence transfection in the same cell culture, this novel technique offers a valuable alternative for TF activity fingerprinting that outclasses classic TF binding ELISAs for significance and elegance.
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Romanov, S., Medvedev, A., Gambarian, M., Poltoratskaya, N., Moeser, M., Medvedeva, L., Gambarian, M., Diatchenko, L., & Makarov, S. (2008). Homogeneous reporter system enables quantitative functional assessment of multiple transcription factors Nature Methods, 5 (3), 253-260 DOI: 10.1038/nmeth.1186