Assay principle

Mammalian cells possess a wide range of mechanisms with which they can specifically respond to signals or stresses evoked by compounds they are confronted with. CALUX® (Chemically Activated LUciferase eXpression) assays form a panel of mammalian cell lines that were modified to produce a quantifiable response in addition to this natural response: If a cell is triggered to generate a response, a reporter gene (luciferase) is transcribed and translated into an enzyme that produces light during a reaction it catalyses. After addition of a substrate (luciferine), light production is quantified using a luminometer. The produced signal is proportional to the evoked effect. An overview of the CALUX® assays currently available is presented here.

Most cellular responses are mediated by a regulatory protein, which is a sensor that detects a certain event and subsequently incites the cellular response to this event. The regulator binds to a specific regulatory element which is present in DNA regions upstream of genes involved in the response. In the CALUX® cell lines these regulatory elements were also placed in front of the luciferase (reporter) gene. Thereby, the production of the corresponding luciferase enzyme is coupled to the natural response of the cell.

Whereas most genes may be involved in multiple responses, the molecular design of the CALUX® assays ensures that the observed response is highly specific for the effect of interest.