One goal of drug discovery and research programs is to reduce false hits as early as possible in the process. Follow-up on false hits is costly in terms of time and resources, and the longer the false hits remain in the drug development pipeline, the more costly they are. So methods that can easily reduce the number of false hits during compound screening early in the discovery process are particularly sought after.
Reporter assays have proven to be invaluable tools for elucidating the mechanisms of action of small molecules or other agents on signaling pathways within cells, and the luciferase reporter assay has become a standard research tool in the biological research laboratory.
However, one caveat of using standard luciferase-based reporter assays for larger-scale compound screening efforts is the frequency of false hits that result from direct interaction of compounds with the luciferase reporter. This issue can be mitigated with a “coincidence reporter” system where two independent reporter proteins are produced from a single transcript. In this type of assay, a bicistronic transcript is stoichiometrically translated into two nonhomologous reporters by means of a 2A “ribosomal skipping” sequence. Since it is unlikely that compounds will interact with two distinct types of reporter, “coincident” responses will indicate on-target activity. Such a coincident reporter system provides an important control against costly false hits early in drug discovery research programs.
A paper published online in ACS Chem Biol in February describes the first successful application of the firefly/NanoLuc luciferase coincidence reporter system to identify new pathways that up-regulate PARK2 expression.
Bacterial exotoxins are scary things. The names of the big three: Tetanus, Anthrax and Botulinum, are sufficient to evoke fear and conjure up images of agony, paralysis, mass hysteria, and permanently frozen Hollywood faces. The worst toxin stories are hard to forget. I can still remember the gruesome textbook case studies that accompanied my bacteriology college lectures. There were the home-canning-gone-horribly-awry botulism stories, the historical examples of agonizing tetanus poisonings, and the less lethal but still nasty cases of fast-acting staph toxins delivered to unsuspecting airline passengers in re-heated meals (avoid the ham sandwiches!). It’s all coming flooding back to me.
The ability to manipulate genes and proteins and observe the effects of specific changes is a foundational aspect of molecular biology. From the first site-directed mutagenesis systems to the development of knockout mice and RNA interference, technologies for making targeted changes to specific proteins to eliminate their expression or alter their function have made tremendous contributions to scientific discovery. 