DNA Cleavage During Pyroptosis

Abstract

Programmed cell death is a normal process in living organisms that removes damaged or infected cells. DNA fragmentation is an important aspect of some forms of programmed cell death, and is a well-recognized feature of apoptosis. DNA damage is also present during pyroptosis, a form of pro-inflammatory programmed cell death mediated by caspase-1. This enzyme cleaves and activates the pore-forming protein, gasdermin D, leading to cell swelling and plasma membrane rupture. The goal of this thesis was to better understand the mechanism and consequences of DNA damage during pyroptosis. We used Salmonella and lethal toxin as pyroptosis inducers and confirmed the presence of DNA damage. We found that release of the DNA-associated nuclear protein HMGB1 also occurs during pyroptosis. Extracellular calcium, which enters pyroptotic cells through gasdermin D pores, is required for both DNA damage and HMGB1 release from the nucleus. However, gasdermin D pores alone are insufficient to stimulate DNA damage. Lastly, we found that DNA from cells undergoing pyroptosis does not appear to resemble apoptotic DNA fragmentation using agarose gel electrophoresis. Together, these results provide further insight into the process of DNA damage during pyroptosis.