The binding site for the transcription factor, NF-κB, on the cystathionine γ-lyase promoter is critical for LPSinduced cystathionine γ-lyase expression

Hydrogen sulfide (H2S) is regarded as the third endogenous gaseous signaling molecule. Cystathioine γ-lyase (CSE), one of the three enzymes in the transsulfuration pathway, is responsible for the production of endogenous H2S. The H2S/CSE signaling pathway is involved in the inflammation induced by lipopolysaccharides (LPS). Therefore, in this study, we investigated the effects of the binding site (on the CSE promoter) for the transcription factor, nuclear factor (NF)-κB, on the transcriptional regulation of the CSE gene in mammalian cells treated with LPS. For this purpose, HEK-293 and COS-7 cells were transfected with 5 µg pGL4.12-KM1478 or 5 µg pGL4.12-KM1478m (mutant) together with the pRL-CMV control vector (0.032 µg for the HEK-293 cells, 0.0032 µg for the COS-7 cells). Subsequently, the cells were treated with LPS for 6 h. The expression of CSE was measured by RT-qPCR. cDNA pooled from J774.1A and RAW264.7 cells treated with LPS for 6 h was used to estimate the quantity of the transcripts. Our results revealed that LPS markedly increased the mRNA and protein expression levels of the CSE gene in the J774.1A and RAW264.7 cells following treatment with LPS for 6 h. In addition, we found that the GGGACATTCC DNA sequence on the promoter of the CSE gene was closely associated with the transcriptional regulation of the CSE gene in the HEK-293 and COS-7 cells treated with LPS. Taken together, our data suggest that the NF-κB binding site on CSE promoter is critical for LPS-induced CSE expression in mammalian cells.