Baculoviral IAP repeat-containing protein 3 (cIAP2) (cIAP2)

Baculoviral IAP repeat-containing protein 3 (cIAP2) is a multi-functional E3 ubiquitin ligase and a member of the inhibitor of apoptosis (IAP) family that plays a pivotal role in regulating cell survival, inflammatory signaling, and innate immunity [1, 3]. The protein is characterized by three N-terminal Baculoviral IAP Repeat (BIR) domains, with the BIR2 and BIR3 domains functioning as the primary interaction sites for the endogenous IAP antagonist Smac/DIABLO [2, 13]. In many human malignancies, cIAP2 is overexpressed or genetically altered, contributing to apoptosis resistance by modulating both canonical and non-canonical NF-κB pathways and preventing the formation of pro-apoptotic signaling complexes [6, 15]. Therapeutic strategies targeting the cIAP2 BIR2/BIR3 domains utilize small-molecule Smac mimetics, which bind to the IAP-binding motif (IBM) groove to trigger a conformational change that induces rapid autoubiquitination and proteasomal degradation of the protein [10, 11]. This degradation sensitizes cancer cells to TNF-α-induced death and promotes the activation of caspases, making it a promising target for overcoming chemoresistance [14, 16]. Clinical development of these inhibitors focuses on their ability to disrupt the pro-survival signaling environment in various solid and hematological tumors [11]. However, the clinical use of these agents is associated with potential safety concerns, most notably cytokine release syndrome and hepatotoxicity, due to the systemic induction of pro-inflammatory cytokines [11, 16]. Additionally, biomarkers such as cIAP1/2 degradation and TNF-α levels are used to monitor the pharmacodynamic efficacy of these treatments in patients [16].

Other names

BIRC3API2HIAP1AIP1CIAP2HAIP1IAP-1MALT2MIHCRNF49TNFR2-TRAF signaling complex protein 1

Smac mimetics bind to the BIR2 and BIR3 domains of cIAP2, mimicking the endogenous antagonist Smac/DIABLO. This binding triggers a conformational change that promotes the dimerization of the C-terminal RING domain, leading to E3 ligase activation, autoubiquitination, and rapid proteasomal degradation of cIAP2. The loss of cIAP2 results in the stabilization of NIK, activation of the non-canonical NF-κB pathway, and the conversion of TNFR1 signaling from a pro-survival to a pro-apoptotic state by facilitating the formation of the RIPK1-FADD-caspase-8 complex.