Molecular cloning and functional analysis of Macaca mulatta STING

Abstract

Stimulator of interferon gene (STING), an adaptor molecule in the immune system, is involved in mediating the response to viral and bacterial infections, anti-tumor immunity, autoimmune diseases, and lipid metabolism. There have been reports on the cloning and function of STING in humans, pigs, chickens, and cats; however, STING has not been characterized in non-human primates or monkeys to date. Therefore, in this study, the rhesus macaque (Macaca mulata) STING gene was cloned, and we performed preliminary functional tests to examine its role in the interferon (IFN) pathway. The M. mulatta STING complementary DNA was 1140 bp in length and encoded 380 amino acid residues. Phylogenetic analysis showed that Homo sapiens and M. mulatta STING are closely related and clustered on the same branch. M. mulatta STING was confirmed to increase the promoter activities of IFN-β, nuclear factor-κB, and interferon-sensitive response element, and STING overexpression increased the mRNA levels of IFN-α, IFN-β, and interferon regulatory factor 3. Infection of Marc-145 cells with porcine reproductive and respiratory syndrome virus activated STING, and its expression increased along with increases in viral multiplicity of infection titer and time. Moreover, STING expression was time- and dose-dependently up-regulated by poly (I:C) and poly (dA:dT) treatments in Marc-145 cells. In summary, these results highlight STING as a vital immune system signal protein in the IFN pathway. This study provides a basis for understanding the immune characteristics of M. mulatta, and may have important implications for both monkey and human diseases.

Keywords: IRF3; Interferon; Macacca mulatta; PRRSV; STING.