Investigation of the role of NLRP13 in cell death

Abstract

NLRP13 is an intracellular protein that is included in the NOD- like receptor family. It contains the N-terminal pyrin domain, central NOD domain, and leucine-rich repeats, LRR at C terminus. Stably NLRP13 expressing THP-1 cells induced a higher pro-inflammatory response upon LPS/ATP treatment and P. Aeruginosa infection. Moreover, the activation of procaspase-8 is relatively increased in the stably NLRP13 expressing THP-1 cell. NLRP13 can interact with caspase-8 according to Co-IP results. Besides these, NLRP3 inflammasome components are significantly higher in the stably NLRP13 expressing THP-1 cells upon inflammasome activation. This thesis study aimed to investigate whether NLRP13 has a role in cell death via the caspase-8 activation complex after inflammasome activation. To elucidate this, Annexin V-PI staining and LDH release assay were performed after pyroptosis induction via inflammasome activation.No significant difference was observed between stably NLRP13 expressing THP-1 cells and control cells. Furthermore, Gasdermin D cleavage was shown to be similar for each group while PARP-1 cleavage in stably NLRP13 expressing THP-1 cells was slightly higher than control. The experiments were repeated after caspase-8 was inhibited. There was no significant difference in Annexin V-PI staining, LDH release assay, and gasdermin D cleavage. However, PARP-1 cleavage was slightly decreased in stably NLRP13 expressing THP-1 cells when caspase-8 was inhibited.It was shown that NLRP13 is not involved directly in pyroptosis via induction of the caspase-8 activation complex; however, it could be involved in the molecular switch mechanism between apoptosis and pyroptosis with the caspase-8 activation complex.