Probing intracellular target engagement in live cells

Published: 2016-03-30


Biological responses of small molecules are a direct consequence of their interactions with intended target proteins, as well as unwanted off-targets. Direct measurement of such compound target engagement in a cellular or tissue context has traditionally been difficult to establish without the development of specific tool compounds and/or protein modifications with reporter functionalities. As this limits these measurements to molecules amenable to the necessary modifications, or genetically modified cell lines, there is a need to validate new technologies that can be applied in primary patient cells.

In collaboration with Pär Nordlund, Karolinska Institutet, researchers from Chemical Biology Consortium Sweden at SciLifeLab have published a study in Nature Communications where they demonstrate high throughput screening capability of a method called cellular thermal shift assay. Targeting intracellular human thymidylate synthase in live cells, their pilot screen identified all drugs within the library known to act on this enzyme. The team further demonstrates that the intracellular target engagement correlates with appearance of the active metabolites of these drugs over time.

While the results are highly encouraging, the present focus is to translate these findings to additional model systems. Provided the possibility to address intracellular target engagement in microplate format, thus allowing for large compound series to be addressed quantitatively, the researchers propose that such experimentation is included as a criterion for validation of the action mechanism of chemical probes.

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