Two orthogonal MAP3K-driven pathways of NLRP1 inflammasome activation revealed by poisonous beetles

ABSTRACT Environmental toxins that cause irritant dermatitis remain poorly understood as activators of innate immune pathways. Here, we identify rove beetle ( Paederus ) and blister beetle ( Meloidae ) toxins as previously unrecognized triggers of the human NLRP1 inflammasome in keratinocytes. Rove beetles, likely through the ribosome inhibitor pederin, activate NLRP1 via translational stalling and the ZAKα-dependent ribotoxic stress response. In contrast, the phosphatase inhibitor cantharidin from blister beetles induces NLRP1 through TAK1-driven hyperphosphorylation of its linker region, independent of ZAKα. In their hyperactivated states, ZAKα and TAK1 share overlapping phosphosites on the NLRP1 disordered linker, including a common essential ‘TZ motif’. In addition, we show that TAK1 and ZAKα are jointly responsible for NLRP1 linker phosphorylation and activation caused by dsRNA and CHIKV infection. These findings reveal medically relevant insect toxins as activators of NLRP1, and uncover parallel MAP3 kinase pathways as converging upstream activating signals for the human NLRP1 inflammasome. GRAPHICAL ABSTRACT KEY POINTS Two dermatitis-causing beetle species induce NLRP1-driven pyroptosis of human keratinocytes Rove beetles, likely via pederin, activate NLRP1 via ribosome inhibition and ZAKɑ-driven RSR Cantharidin from blister beetles activates human via TAK1-, instead of ZAKɑ-driven hyperphosphorylation of the NLRP1 linker region Shared phosphosites by TAK1 and ZAKɑ on NLRP1 contribute to dsRNA-driven NLRP1 activation