Mapping cellular response to destabilized transthyretin reveals cell- and amyloidogenic protein-specific signatures

In ATTR amyloidosis, transthyretin (TTR) protein is secreted from the liver and deposited as toxic aggregates at downstream target tissues. Despite recent advancements in treatments for ATTR amyloidosis, the mechanisms underlying misfolded TTR-mediated cellular damage remain elusive. In an effort to define early events of TTR-associated stress, we exposed neuronal (SH-SY5Y) and cardiac (AC16) cells to wild-type and destabilized TTR variants (TTR^V122I (p.V142I) and TTR^L55P (p.L70P)) and performed transcriptional (RNAseq) and epigenetic (ATACseq) profiling. We subsequently compared TTR-responsive signatures to cells exposed to destabilized antibody light chain protein associated with AL amyloidosis as well as ER stressors (thapsigargin, heat shock). In doing so, we observed overlapping, yet distinct cell type- and amyloidogenic protein-specific signatures, suggesting unique responses to each amyloidogenic variant. Moreover, we identified chromatin level changes in AC16 cells exposed to mutant TTR that resolved upon pre-incubation with kinetic stabilizer tafamidis. Collectively, these data provide insight into the mechanisms underlying destabilized protein-mediated cellular damage and provide a robust resource representing cellular responses to aggregation-prone proteins and ER stress.

在ATTR淀粉样变性（ATTR amyloidosis）中，转甲状腺素蛋白（transthyretin, TTR）由肝脏合成并分泌，随后以毒性聚集物的形式沉积于下游靶组织。尽管ATTR淀粉样变性的治疗手段近年来已有长足进步，但错误折叠TTR介导的细胞损伤的具体分子机制仍有待阐明。为明确TTR相关应激的早期事件，我们将神经元（SH-SY5Y）与心肌（AC16）细胞暴露于野生型及不稳定型TTR变异体[TTR^V122I（p.V142I）和TTR^L55P（p.L70P）]，并开展了转录组（RNA测序，RNAseq）与表观基因组（转座酶可及性测序，ATACseq）谱分析。随后，我们将TTR应答特征谱与暴露于AL淀粉样变性（AL amyloidosis）相关不稳定抗体轻链蛋白以及内质网应激诱导剂（毒胡萝卜素、热休克）的细胞进行了比对。结果显示，不同处理组的细胞特征谱既存在重叠，又具有细胞类型特异性与淀粉样蛋白特异性，提示不同淀粉样变异体可触发独特的细胞应答。此外，我们还发现，突变型TTR处理后的AC16细胞所出现的染色质水平改变，可通过动力学稳定剂他法米迪（tafamidis）预孵育得以逆转。综上，本数据集不仅为阐明不稳定蛋白介导的细胞损伤机制提供了新的研究视角，同时也为探究易聚集蛋白与内质网应激的细胞应答提供了高质量的研究资源。