Detecting "different": Pyrin senses modified GTPases

Abstract

Pathogenic bacteria secrete effector proteins that target host cell Rho GTPases to manipulate the actin cytoskeleton. A recent study in Nature identifies the Pyrin inflammasome as a sensor of this pathogenic process.

Figure 1

Effector-triggered and pattern-triggered immunity in mammalian cells. Bacterial effectors (shown in red) gain access to the cytosol, where they manipulate cellular processes through pore formation in the cellular membrane (sensed by NLRP3), GTPase inactivation (sensed by Pyrin), GTPase activation (sensed by NOD1), or MAPK inactivation (sensed by NLRP1b). Bacterial patterns are released or secreted from attaching or invading bacteria, where they are detected by NLRC4 (sensing flagellin and components of the Type III Secretion System), NOD1 and NOD2 (sensing peptidoglycan), AIM2 (sensing DNA), and Caspase-11/NLRP3 (sensing LPS).