NF-κB regulates the expression of STING via alternative promoter usage

Stimulator of interferon genes (STING) is a transmembrane protein in endoplasmic reticulum and plays crucial roles in autophagy, antiviral and anti-tumor responses. However, there are few studies on the transcriptional regulation mechanism of STING.

The 5' RACE experiment was used to determine the location of STING promoters. Luciferase reporting assay confirmed the activity and core region of STING internal promoter. Site-directed mutagenesis confirmed that NF-κB regulates the activity of STING promoters. The regulation of NF-κB on STING was investigated by real-time quantitative PCR, western blot, chromatin immunoprecipitation assay and lipopolysaccharide (LPS) inflammatory cell model.

There was also a transcription start site at the 17 bp sequence upstream of STING second exon. STING-285 was the core region of the internal promoter. After NF-κB binding site mutation, the activity of STING internal promoter decreased significantly. In addition, we found that NF-κB can bind to the promoter region of wild-type STING. Overexpression of NF-κB significantly increased the activity of STING internal promoter and wild-type promoter, while knockdown of endogenous NF-κB significantly inhibited the activity of STING promoters. The binding of NF-κB to STING promoters in vivo were confirmed by chromatin immunoprecipitation assay. Meanwhile, we stimulated HeLa cells with LPS to activate the NF-κB pathway and found that STING expression was up-regulated.

These results suggest that transcription factor NF-κB positively regulates the expression of STING via alternative promoter usage. This provides a new basis and potential drug targets for the clinical treatment of STING related diseases.