Effects of physiological and synthetic IAP antagonism on c-IAP dependent signaling

Cellular inhibitor of apoptosis proteins 1 and 2 (c-IAP1/2) play central roles in signal transduction mediated by numerous receptors that participate in inflammatory and immune responses. In certain pathways, such as activation of NF-kB, their degradation is a major regulatory event and is physiologically induced by activation of receptors. Additionally, a number of synthetic compounds have been developed that also target the c-IAPs and induce their degradation. However, the extent of a synthetic IAP antagonist’s ability to mirror the transcriptional program by a physiological signal remains unclear. Here we take a systems approach to compare the transcriptional programs triggered by activation of CD30, a well-characterized receptor previously shown to induce the degradation of the c-IAPs, to SM-164, a synthetic IAP antagonist that specifically triggers c-IAP degradation. Employing a technique that allows the specific analysis of newly transcribed RNA, we have generated comparative transcriptome profiles for CD30 activation and SM-164 treatment. Analysis of these profiles revealed that the genes regulated by each stimulus were not completely shared, indicating novel functions of IAP antagonists and consequences of c-IAP1/2 degradation. The data identified a role for c-IAP1/2 in the regulation of the ribosome and protein synthesis, which was subsequently confirmed by biological assays. These findings expand our knowledge of the roles of c-IAP1/2 in signaling and provide insight into the mechanism of synthetic IAP antagonists, furthering our understanding of their therapeutic potential. This submission contains two different experiments. In experiment 1, cells were exposed to drug treament (DMSO or SM-164) for 3 hours. In experiment 2, cells were exposed to an adherent layer of CHO cells either expressing or not CD30L. Each treatment in each experiment was conducted once, leading to a total of 4 samples.

细胞凋亡抑制蛋白1和2（cellular inhibitor of apoptosis proteins 1 and 2, c-IAP1/2）在众多参与炎症与免疫应答的受体介导的信号转导过程中发挥核心作用。在部分信号通路中，比如核因子κB（nuclear factor kappa-light-chain-enhancer of activated B cells, NF-κB）的激活，c-IAP1/2的降解是关键调控事件，且可通过受体激活实现生理性诱导。此外，学界已开发出多种靶向c-IAPs并诱导其降解的合成类化合物。然而，合成型IAP拮抗剂（IAP antagonist）在多大程度上能够模拟生理性信号所触发的转录程序，目前仍不清楚。
本研究采用系统生物学方法，对比了CD30激活与SM-164处理所触发的转录程序：CD30是一种已被充分表征的受体，此前研究已证实其可诱导c-IAPs降解；而SM-164则是一种可特异性诱导c-IAP降解的合成型IAP拮抗剂。本研究借助一种可特异性分析新生转录RNA的技术，构建了CD30激活与SM-164处理的比较转录组谱。对该谱图的分析显示，两种刺激所调控的基因并非完全重合，这提示了IAP拮抗剂的新功能以及c-IAP1/2降解的潜在下游效应。本数据集揭示了c-IAP1/2在核糖体调控与蛋白质合成过程中的作用，该结论后续通过生物学实验得到了验证。
上述发现拓展了我们对c-IAP1/2在信号转导中功能的认知，同时阐明了合成型IAP拮抗剂的作用机制，有助于进一步理解其治疗潜力。本数据集包含两组独立实验：实验1中，细胞经药物处理（二甲基亚砜（dimethyl sulfoxide, DMSO）或SM-164）3小时；实验2中，细胞与表达或不表达CD30配体（CD30 ligand, CD30L）的贴壁中国仓鼠卵巢细胞（Chinese hamster ovary cell, CHO）共培养。每组处理均仅设置一次重复，最终共获得4份样本。