The Nrf2 Activator, tBHQ, Differentially Affects Early Events Following Stimulation of Jurkat Cells

Abstract

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that is activated by cellular stresses, such as oxidative compounds. After activation, Nrf2 induces transcription of its target genes, many of which have cytoprotective functions. Previously, we have shown that activation of Nrf2 by tert-butylhydroquinone (tBHQ) skews murine CD4⁺ T-cell differentiation. Although the role of Nrf2 in murine T cells is somewhat characterized, it is largely uncharacterized in human T cells. Therefore, the aim of the current studies was to characterize the effects of the Nrf2 activator, tBHQ, on the early events of human CD4⁺ T-cell activation. Pretreatment of Jurkat T cells with tBHQ, prior to activation with anti-CD3/anti-CD28, diminished the production of interleukin-2 (IL-2) at both the transcript and protein levels. Similarly, the expression of CD25 also diminished, albeit to a lesser degree than IL-2, after pretreatment with tBHQ. The decrease in IL-2 production was not due to decreased nuclear translocation of c-fos or c-jun. Although tBHQ caused both a delay and a decrease in Ca²⁺ influx in activated Jurkat cells, no decrease in nuclear factor of activated T cells (NFAT) DNA binding or transcriptional activity was observed. In contrast to NFAT, tBHQ significantly decreased NFκB transcriptional activity. Collectively, our studies show that the Nrf2 activator, tBHQ, inhibits IL-2 and CD25 expression, which correlates with decreased NFκB transcriptional activity in activated Jurkat cells. Overall, our studies suggest that Nrf2 represents a novel mechanism for the regulation of both human and mouse T cell function.

The Nrf2 activator tBHQ inhibits T cell activation of primary human CD4 T cells

“…Consistent with other cell types, tBHQ treatment increased expression of the Nrf2 target genes, heme oxygenase 1 (HMOX-1), NAD(P)H quinone oxidoreductase 1 (NQO1), and glutamate-cysteine ligase, catalytic subunit (GCLC), in human peripheral blood mononuclear cells (Fig. 1) [15, 16]. In addition, tBHQ caused a modest induction of NRF2 mRNA expression itself, which has also been observed previously in primary mouse T cells and suggests that NRF2 upregulates itself.…”

“…Our previous studies showed the Nrf2 activator tBHQ inhibited IL-2 production in activated Jurkat T cells, but the effect of tBHQ on primary human T cells has not been fully characterized [16]. Therefore, we determined the effect of tBHQ treatment on IL-2 production by PBMCs activated with anti-CD3/anti-CD28, a T cell specific activator.…”

“…Several transcription factors have been shown to be important in T cell activation, including NFAT, NFκB, and AP-1 [17, 20]. Our previous studies demonstrated that the Nrf2 activator tBHQ inhibits IL-2 secretion, CD25 expression, and NFκB induction in activated Jurkat cells [16]. The purpose of the present studies was to determine the effects of the Nrf2 activator tBHQ on the early events following T cell activation in primary human cells.…”

“…Nrf2-null mice develop a lupus-like autoimmune disease, and have increased sensitivity to inflammation and infection in models such as sepsis and lung injury [10–14]. Recently, our laboratory demonstrated that Nrf2 modulates T cell responses in primary mouse CD4 T cells and Jurkat T cells [15, 16]. Collectively, this indicates that Nrf2 modulates immune responses in a variety of different models and cell types.…”

Nrf2 mitigates LRRK2- and α-synuclein–induced neurodegeneration by modulating proteostasis

“…We adapted this approach by visualizing Nrf2 activation in real time in single cells by placing the expression of the fluorescent protein mApple under the control of the ARE sequence. To validate the ARE_mApple reporter gene, HEK293 cells were cotransfected with Venus, as a morphology marker, and ARE_mApple and treated with tertiary butylhydroquinone (tBHQ), an activator of endogenous Nrf2 (26). At 24 h posttransfection, cells were imaged, and ARE_mApple fluorescence was measured.…”