PIDD mediates and stabilizes the interaction between RAIDD and Caspase-2 for the PIDDosome assembly

Abstract

The PIDDosome, which is an oligomeric signaling complexcomposed of PIDD, RAIDD and caspase-2, can induceproximity-based dimerization and activation of caspase-2. Inthe PIDDosome assembly, the adaptor protein RAIDDinteracts with PIDD and caspase-2 via CARD:CARD andDD:DD, respectively. To analyze the PIDDosome assembly,we purified all of the DD superfamily members and performedbiochemical analyses. The results revealed that caspase-2CARD is an insoluble protein that can be solubilized by itsbinding partner, RAIDD CARD, but not by full-length RAIDD;this indicates that full-length RAIDD in closed states cannotinteract with caspase-2 CARD. Moreover, we found thatcaspase-2 CARD can be solubilized and interact withfull-length RAIDD in the presence of PIDD DD, indicating thatPIDD DD initially binds to RAIDD, after which caspase-2 canbe recruited to RAIDD via a CARD:CARD interaction. Ourstudy will be useful in determining the order of assembly ofthe PIDDosome. [BMB Reports 2013; 46(9): 471-476]

Keywords

• Apoptosis
• CARD
• Caspase-2
• DD
• PIDD
• PIDDosome
• RAIDD