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Functional and Evolutionary Analyses Identify Proteolysis as a General Mechanism for NLRP1 Inflammasome Activation

Fig 2

NLRP1A is activated by N-terminal proteolysis.

(A) The amino acid sequence of the first 244 residues of NLRP1AB6 was aligned to NLRP1B129 and NLRP1BB6. The arrow above the alignment indicates the LF-cleavage site in NLRP1B129. (B) 293T cells were transfected for 36h with 200ng empty vector (V) or plasmids pcDNA3.1-HA-NLRP1B129 or -NLRP1AB6-MYC (CMV promoter) along with 200ng mCASP1 and 200ng mIL-1β expression vectors. Cells were treated overnight with anthrax lethal toxin (LeTx, 1μg/ml) 24h post-transfection, and then lysates were analyzed by immunoblotting (IB) with the indicated antibodies. (C) 293T cells were transfected for 36h with plasmids encoding 400ng GFP-HA-NLRP1B129 or GFP-HA-NLRP1AB6 (under the control of the LTR promoter in pMSCV) or with mutants engineered to contain an N-terminal TEV protease site. Cells were also co-transfected with 100ng empty vector (V) or plasmids encoding TEV-protease (pTEV) or lethal factor protease (pLF), plus 300ng empty pMSCV. (D) To assess IL-1β cleavage, cells were transfected as in C, but with 8ng of GFP-HA-NLRP1B and co-transfected with vectors encoding 200ng mCASP1 and 200ng mIL-1β. For panels B-D, data shown are representative of at least three similar experiments.

Fig 2