NRF2 Regulates Cystathionine Gamma-Lyase Expression and Activity in Primary Airway Epithelial Cells Infected with Respiratory Syncytial Virus

Abstract

Cystathionine-y-lyase (CSE) is a critical enzyme for hydrogen sulfide (H2S) biosynthesis and plays a key role in respiratory syncytial virus (RSV) pathogenesis. The transcription factor NRF2 is the master regulator of cytoprotective and antioxidant gene expression, and is degraded during RSV infection. While some evidence supports the role of NRF2 in CSE gene transcription, its role in CSE expression in airway epithelial cells is not known. Here, we show that RSV infection decreased CSE expression and activity in primary small airway epithelial (SAE) cells, while treatment with tert-butylhydroquinone (tBHQ), an NRF2 inducer, led to an increase of both. Using reporter gene assays, we identified an NRF2 response element required for the NRF2 inducible expression of the CSE promoter. Electrophoretic mobility shift assays demonstrated inducible specific NRF2 binding to the DNA probe corresponding to the putative CSE promoter NRF2 binding sequence. Using chromatin immunoprecipitation assays, we found a 50% reduction in NRF2 binding to the endogenous CSE proximal promoter in SAE cells infected with RSV, and increased binding in cells stimulated with tBHQ. Our results support the hypothesis that NRF2 regulates CSE gene transcription in airway epithelial cells, and that RSV-induced NRF2 degradation likely accounts for the observed reduced CSE expression and activity.

SARS-CoV-2 Inhibits NRF2-Mediated Antioxidant Responses in Airway Epithelial Cells and in the Lung of a Murine Model of Infection

“…In experimental infections with influenza virus or RSV, exogenous treatment with the AOE CAT significantly reduced viral titers in the lung of mice ( 52 , 53 ). In addition, NRF2 controls the expression of cystathionine-γ-lyase (CSE) in airway epithelial cells ( 54 ), which is a critical enzyme for the biosynthesis of hydrogen sulfide, which has a broad antiviral activity ( 55 – 57 ) and whose expression was decreased in RSV-infected Nrf2 −/− mice compared to WT mice ( 47 ). NRF2 has also been shown to affect innate immunity, including macrophage and dendritic cell antigen-presenting functions, and T helper cell balance (i.e., favoring Th1 responses), while oxidative stress might be involved in the loss of naive T cells and decrease in Th1 immunity ( 46 , 58 ).…”

MLN-4760 Induces Oxidative Stress without Blood Pressure and Behavioural Alterations in SHRs: Roles of Nfe2l2 Gene, Nitric Oxide and Hydrogen Sulfide

“…However, we found positive correlations between Nfe2l2 gene expression and expressions of Mpst , Cth and Cbs genes, suggesting the regulatory role of NRF2 in expression of these genes. Such a mechanism of NRF2-regulated gene expression of H 2 S-producing enzymes was described previously in in vitro [ 76 , 77 ] studies or in mice subjected to ischemia-induced chronic heart failure [ 78 ].…”

New insights into the regulation of Cystathionine beta synthase (CBS), an enzyme involved in intellectual deficiency in Down syndrome

“…The transcription factor NF-E2-related factor 2 (Nrf2) encodes a protein which has a short half-time of only 30 min and which stability is controlled through the regulation of its turnover by the ubiquitin-proteasome system. It controls the expression of over 100 genes, including CBS ( Hourihan et al, 2013 ; Liu et al, 2020 ), CSE ( Jamaluddin et al, 2022 ), and NQO1 ( Mutter et al, 2015 ), three genes that play an important role in cell response to oxidative stress. The homolog system to Nrf2 in yeast is Yap1p, which also confers protection against oxidative stress and regulates the expression of yeast homologs of CBS and CSE ( Orumets et al, 2012 ).…”