Improved health span and lifespan extension in a wide phylogenetic range of species is associated with the induction of the environmental cell stress response through a signalling pathway regulated by the transcription factor Nrf2. Phytochemicals which stimulate this response may form part of therapeutic interventions which stimulate endogenous cytoprotective mechanisms, thereby delaying the onset of age-related diseases and promoting healthy ageing in humans. In order to identify compounds that activate the Nrf2 pathway, a cell-based reporter system was established in HepG2 cells using a luciferase reporter gene under the control of the Nqo1 promoter. Sulforaphane, an isothiocyanate derived from cruciferous vegetables and a known activator of the Nrf2 pathway, was used to validate the reporter system. The transfected cell line HepG2 C1 was subsequently used to screen natural product libraries. Five compounds were identified as activating the bioluminescent reporter by greater than 5-fold. The two most potent compounds, MBC20 and MBC37, were further characterised and shown to stimulate endogenous cytoprotective gene and protein expression. The bioluminescent reporter system will allow rapid, in vitro identification of novel compounds that have the potential to improve health span through activation of the environmental stress response.
Bibliographical noteThis work was funded by The Scottish Government Rural and Environment Science and Analytical Services Division (RESAS), Scotland, United Kingdom and the Biotechnology and Biological Sciences Research Council (BBSRC; East-Bio Doctoral Training Partnership), United Kingdom. The funders had no role in the design of the study, the analysis and interpretation of the data, or the publication process. The authors wish to thank Prof. John Hayes, University of Dundee, for the NQO1-luciferase construct and Prof. Gary Felsenfeld, NIH, Bethesda for the plasmid pJC13-1.
- cell-based assay
- OXIDATIVE STRESS
- Cell-based assay
- ADAPTIVE RESPONSE