Nuclear factor erythroid 2-related factor 2 (Nrf2) is a stress activated transcription factor, activated by stimuli such as electrophilic compounds and other reactive xenobiotics. Previously, we have shown that the commonly-used food additive and Nrf2 activator, tert-butylhydroquinone (tBHQ), suppresses IL-2 production, CD25 expression, and NFκB activity in human Jurkat T cells. The purpose of the current studies was to determine whether these effects were dependent upon Nrf2 by developing a human Nrf2-null T cell model using CRISPR/Cas9 technology. The current studies show that suppression of CD25 expression by tBHQ is partially dependent on Nrf2, whereas inhibition of IL-2 secretion is largely Nrf2-independent. Interestingly, tBHQ inhibited NFκB activation in a Nrf2-independent manner. This was an unexpected finding since Nrf2 inhibits NFκB activation in other models. These results lead us to investigate another, more potent, Nrf2 activator, the synthetic triterpenoid CDDO-Imidazolide (CDDO-Im). Treatment of wild-type and Nrf2-null Jurkat T cells with CDDO-Im resulted in a Nrf2-dependent suppression of IL-2. Furthermore, susceptibility to reactive oxygen species was significantly enhanced in the Nrf2-null clones as determined by decreased mitochondrial membrane potential and cell viability. Importantly, this study is the first to describe the generation of a human Nrf2-null model, which is likely to have multiple applications in immunology and cancer biology. Collectively, this study demonstrates a role for Nrf2 in the effects of CDDO-Im on CD25 and IL-2 expression, whereas the effect of tBHQ on these parameters is complex and likely involves modulation of multiple stress-activated transcription factors, including NFκB and Nrf2.
- The American Society for Pharmacology and Experimental Therapeutics