Direct Regulation of Extracellular Proteostasis by the Unfolded Protein Response

通过未折叠的蛋白质反应直接调节细胞外蛋白质稳态

• 批准号: 9065690
• 负责人: Rockland Luke Wiseman
• 金额: $ 42.02万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9065690
• 关键词: Address; Alzheimer' s Disease; Amyloidosis; Attenuated; Binding; Biochemical; Biological; Biological Assay; Caenorhabditis elegans; Cell Culture Techniques; Cells; Complex; Creutzfeldt-Jakob Syndrome; DNA Sequence Alteration; Degenerative Disorder; Deposition; Disease; Endoplasmic Reticulum; Environment; Extracellular Protein; Extracellular Space; Genetic; Goals; Health; Homeostasis; Individual; Link; Mammalian Cell; Mediating; Mitotic; Modeling; Molecular; Molecular Chaperones; Neurons; Outcome; Pathogenesis; Pathologic; Pathology; Pathway interactions; Phenotype; Prealbumin; Predisposing Factor; Prions; Protein Conformation; Proteins; Regulation; Signal Pathway; Signal Transduction; Stress; Structure; Therapeutic; Tissues; Variant; age related; biological adaptation to stress; endoplasmic reticulum stress; extracellular; interest; meetings; normal aging; novel therapeutics; prevent; protein aggregation; response; small molecule; sulfated glycoprotein 2; transcription factor

 DESCRIPTION (provided by applicant): The misfolding and extracellular aggregation of destabilized, amyloidogenic proteins is inextricably linked to degenerative phenotypes in over 30 protein aggregation (i.e., amyloid) diseases including Alzheimer's disease, Creutzfeldt-Jakob disease and the systemic amyloidoses. Significant pharmacologic and genetic evidence confirms a causal relationship between protein aggregation and degeneration of post-mitotic tissues in these diseases. The importance of extracellular protein aggregation in amyloid disease pathology has stimulated significant experimental effort focused on defining the organismal and cellular pathways that regulate protein homeostasis (or proteostasis) in the extracellular environment. One such pathway is the Unfolded Protein Response (UPR) - the stress-responsive signaling pathways responsible for regulating proteostasis within the secretory pathway in response to endoplasmic reticulum (ER) stress. Previous results from our lab and others have shown that the UPR indirectly influences extracellular aggregation of destabilized, amyloidogenic proteins by reducing their secretion from mammalian cells, thus decreasing extracellular protein levels available for concentration-dependent aggregation. Here, we hypothesize that UPR activation also directly regulates extracellular proteostasis through the increased expression and secretion of extracellular chaperones that prevent the proteotoxic aggregation of destabilized, aggregation-prone proteins. We have identified the ER-targeted HSP40 co-chaperone ERdj3 as a UPR regulated, secreted chaperone that promotes extracellular proteostasis in response to ER stress. We show that ERdj3 attenuates the aggregation and proteotoxicity of disease-associated, aggregation-prone secreted proteins including Aß40 and toxic prion protein (TPrP). Additionally, we show that ERdj3 is co-secreted in a complex with destabilized, aggregation-prone proteins under conditions where ER proteostasis pathways are overwhelmed, providing a mechanism to preemptively protect the extracellular environment from proteotoxic extracellular protein aggregation. In this application, we expand on these findings using biophysical, biochemical and cell biological approaches to define the molecular mechanisms by which UPR-dependent ERdj3 secretion protects the extracellular environment against proteotoxic protein conformations. Through these efforts, we will identify specific aspects of UPR-regulated ERdj3 secretion directly involved in preventing the proteotoxic aggregation of destabilized secreted proteins associated with amyloid disease pathology. These results will demonstrate that altered UPR signaling, such as those that occur during normal aging or in response to amyloid-disease associated genetic mutations, can facilitate aging-dependent extracellular protein aggregation involved in amyloid disease pathogenesis. Furthermore, we will identify components of UPR signaling pathways that can be therapeutically targeted to promote extracellular proteostasis and prevent extracellular protein aggregation, revealing a new strategy to attenuate proteotoxicity of secreted proteins involved in the pathology of amyloid diseases.

 描述（由申请人提供）：不稳定的淀粉样蛋白质的错误折叠和细胞外聚集与超过30种蛋白质聚集（即，淀粉样蛋白）疾病，包括阿尔茨海默病、克雅氏病和系统性淀粉样蛋白病。重要的药理学和遗传学证据证实了这些疾病中蛋白质聚集和有丝分裂后组织变性之间的因果关系。淀粉样蛋白病病理学中细胞外蛋白聚集的重要性已经刺激了大量的实验努力，这些实验努力集中于定义在细胞外环境中调节蛋白质稳态（或蛋白质稳态）的生物体和细胞途径。一种这样的途径是未折叠蛋白反应（UPR）-负责调节分泌途径内的蛋白稳态以响应内质网（ER）应激的应激反应性信号传导途径。来自我们实验室和其他实验室的先前结果已经表明，UPR通过减少其从哺乳动物细胞的分泌来间接影响不稳定的淀粉样蛋白的细胞外聚集，从而降低可用于浓度依赖性聚集的细胞外蛋白水平。在这里，我们假设UPR激活也直接调节细胞外蛋白质稳态通过增加的表达和分泌的细胞外伴侣，防止蛋白毒性聚集的不稳定，聚集倾向的蛋白质。我们已经确定ER靶向的HSP 40共伴侣ERdj 3作为UPR调节的分泌型伴侣，其响应于ER应激促进细胞外蛋白质稳态。我们表明ERdj 3减弱疾病相关的、易聚集的分泌蛋白的聚集和蛋白毒性，所述分泌蛋白包括A β 40和毒性朊病毒蛋白（TPrP）。此外，我们表明，ERdj 3是共同分泌的一个复杂的不稳定，聚集倾向的蛋白质的条件下，ER蛋白酶抑制途径被淹没，提供了一种机制，先发制人地保护细胞外环境从蛋白毒性细胞外蛋白质聚集。在本申请中，我们使用生物物理学、生物化学和细胞生物学方法来扩展这些发现，以定义UPR依赖性ERdj 3分泌保护细胞外环境免受蛋白毒性蛋白构象影响的分子机制。通过这些努力，我们将确定UPR调节的ERdj 3分泌的具体方面，直接参与预防与淀粉样蛋白疾病病理学相关的不稳定分泌蛋白的蛋白毒性聚集。这些结果将证明，改变的UPR信号，如那些发生在正常衰老或淀粉样蛋白疾病相关的基因突变，可以促进衰老依赖性细胞外蛋白聚集参与淀粉样蛋白疾病的发病机制。此外，我们将确定UPR信号通路的组成部分，可以在治疗上有针对性地促进细胞外蛋白质稳态和防止细胞外蛋白质聚集，揭示了一种新的策略，以减轻蛋白毒性的分泌蛋白参与淀粉样疾病的病理。