Role of the cGAS-STING Signaling Pathway in 4-Hydroxynonenal-Induced Cellular Senescence

Abstract

The cGAS-STING signaling pathway is responsible for recognizing cytosolic doublestranded DNA and initiating an inflammatory response as part of the innate immune system. This pathway has been correlated with the development of cellular senescence, a state of irreversible cell cycle arrest. Senescent cells accumulate with age and a senescent phenotype is associated with chronic inflammation and numerous age-related diseases. There is a lack of research connecting the cGAS-STING pathway to cellular senescence initiated by endogenous inducers of senescence. Using the endogenously produced reactive lipid aldehyde 4-Hydroxynonenal (4- HNE) to induce senescence, various small molecule inhibitors to components of the cGASSTING pathway were used to further examine this connection. Murine stromal vascular fraction cells and IMR90 cells, an immortalized human lung fibroblast cell line, were cultured and treated with 4-HNE in addition with two different small-molecule inhibitors of cGAS-STING pathway components. Using immunoblotting and quantitative real-time PCR techniques, protein and mRNA levels were analyzed to assess cGAS-STING pathway activation and the presence of a senescent phenotype with and without inhibitor presence. The results show upregulation of numerous protein and mRNA markers suggesting cGAS-STING pathway activation, as well as evidence of a senescent phenotype in cells treated with 4-HNE. However, both small molecule inhibitors showed inconsistent results in preventing a senescent phenotype. The results suggest the possibility of a mechanistic correlation between the cGAS-STING pathway and cellular senescence, however future work is required to further examine this relationship in the context of 4-HNE.