Journal Article

Molecular determinants of Smac mimetic induced degradation of cIAP1 and cIAP2

Tenev, T, Benetatos, C, Feltham, R, Darding, M, Silke, J, Bianchi, K, Meier, P

2011

Overview

The inhibitors of apoptosis (IAP) proteins cIAP1 and cIAP2 have recently emerged as key ubiquitin-E3 ligases regulating innate immunity and cell survival. Much of our knowledge of these IAPs stems from studies using pharmacological inhibitors of IAPs, dubbed Smac mimetics (SMs). Although SMs stimulate auto-ubiquitylation and degradation of cIAPs, little is known about the molecular determinants through which SMs activate the E3 activities of cIAPs. In this study, we find that SM-induced rapid degradation of cIAPs requires binding to tumour necrosis factor (TNF) receptor-associated factor 2 (TRAF2). Moreover, our data reveal an unexpected difference between cIAP1 and cIAP2. Although SM-induced degradation of cIAP1 does not require cIAP2, degradation of cIAP2 critically depends on the presence of cIAP1. In addition, degradation of cIAP2 also requires the ability of the cIAP2 RING finger to dimerise and to bind to E2s. This has important implications because SM-mediated degradation of cIAP1 causes non-canonical activation of NF- κ B, which results in the induction of cIAP2 gene expression. In the absence of cIAP1, de novo synthesised cIAP2 is resistant to the SM and suppresses TNF α killing. Furthermore, the cIAP2-MALT1 oncogene, which lacks cIAP2's RING, is resistant to SM treatment. The identification of mechanisms through which cancer cells resist SM treatment will help to improve combination therapies aimed at enhancing treatment response.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/92/609 / Animals / Apoptosis / Apoptosis Regulatory Proteins / Baculoviral IAP Repeat-Containing 3 Protein / Biochemistry / Biomedical and Life Sciences / Breast cancer / Cancer research / Caspases - genetics / Caspases - metabolism / Cell Biology / Cell Cycle Analysis / Cell death / Cell Death - physiology / Fibroblasts - cytology / Fibroblasts - physiology / Gene Expression Regulation / HEK293 Cells / Humans / Inhibitor of Apoptosis Proteins - chemistry / Inhibitor of Apoptosis Proteins - genetics / Inhibitor of Apoptosis Proteins - metabolism / Intracellular Signaling Peptides and Proteins - genetics / Intracellular Signaling Peptides and Proteins - metabolism / Kinases / Laboratories / Life Sciences / Medical research / Mice / Mice, Knockout / Mitochondrial Proteins - genetics / Mitochondrial Proteins - metabolism / Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein / Neoplasm Proteins - genetics / Neoplasm Proteins - metabolism / NF-kappa B - genetics / NF-kappa B - metabolism / Original Paper / Proteins / Recruitment / RNA, Small Interfering - metabolism / Stem Cells / TNF Receptor-Associated Factor 2 - genetics / TNF Receptor-Associated Factor 2 - metabolism / Tumor Necrosis Factor-alpha - genetics / Tumor Necrosis Factor-alpha - metabolism / Tumor necrosis factor-TNF / Ubiquitin-Protein Ligases