Caspase-11 Controls Interleukin-1β Release through Degradation of TRPC1

• TRPC1 cation channel subunit is a substrate for inflammatory caspase-11
• TRPC1 is degraded in macrophages following LPS treatment in vitro
• Trpc1−/− mice secrete more IL-1β in the serum after LPS challenge
• TRPC1 inhibits IL-1β release but not caspase-1 activation or cell death

SummaryCaspase-11 is a highly inducible caspase that controls both inflammatory responses and cell death. Caspase-11 controls interleukin 1β (IL-1β) secretion by potentiating caspase-1 activation and induces caspase-1-independent pyroptosis downstream of noncanonical NLRP3 inflammasome activators such as lipopolysaccharide (LPS) and Gram-negative bacteria. However, we still know very little about the downstream mechanism of caspase-11 in regulating inflammation because the known substrates of caspase-11 are only other caspases. Here, we identify the cationic channel subunit transient receptor potential channel 1 (TRPC1) as a substrate of caspase-11. TRPC1 deficiency increases the secretion of IL-1β without modulating caspase-1 cleavage or cell death in cultured macrophages. Consistently, trpc1−/− mice show higher IL-1β secretion in the sepsis model of intraperitoneal LPS injection. Altogether, our data suggest that caspase-11 modulates the cationic channel composition of the cell and thus regulates the unconventional secretion pathway in a manner independent of caspase-1.

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