Collagen Proteostasis in Heath and Disease

胶原蛋白是动物体内含量最丰富的蛋白质，占人类总蛋白质的三分之一。 作为骨、皮肤、软骨和基底膜等组织的主要蛋白质成分， 膜，它构成了动物生命的分子支架。这种普遍存在的蛋白质对细胞来说是一种挑战 生产，需要高度协调的细胞内折叠、组装和质量控制过程。由于 胶原性细胞外基质的分级性质，以及它们的物理和生化特性 这些上游的细胞内过程从根本上定义了组织。缺陷，无论是遗传的还是其他的- 因此，对胶原蛋白平衡的任何方面都有害的物质可以影响细胞的健康或功能，并提出- 通向细胞外基质，导致所谓的胶原病。不幸的是，这些杂物- 患者几乎普遍缺乏有效的、改变疾病的治疗方法。 目前胶原病的治疗策略侧重于再生疗法，努力 加强细胞外基质本身，或姑息治疗。这些方法都不是为了解决UP- 导致疾病的流问题：未能正确折叠和质量控制胶原分子本身。如果 胶原蛋白平衡的破坏可以有效地解决，下游症状的靶向是 目前的临床策略将得到缓解。事实上，蛋白质抑制增强已被证明是非常有效的- 在包括囊性纤维化在内的许多其他遗传性疾病中都是致命的，但它还没有在 胶原病。其中一个障碍是对胶原蛋白前体的关键决策点认识不足。 稳定网络。另一个问题是蛋白抑制剂靶向干预的临床前测试面临的挑战 这种疾病需要强大的，但生物化学上服从的组织模型系统来进行发现工作。 这份R01提案旨在解决这些知识差距，包括确定和阐明关键机制- 蛋白质平衡网络的细胞内折叠异常和质量控制及治疗潜力的评估 胶原病中的工作靶向治疗。在目标1中，高度保守的前胶原的功能 N-葡聚糖在促进折叠、实现质量控制和确定折叠的前胶原何时准备好 分泌将通过在细胞和体内的综合工作来阐明，这将揭示分子 胶原糖蛋白稳定的机制。人们的期望表明，长期被忽视的前胶原蛋白 N-葡聚糖实际上是胶原蛋白稳定的关键支点。在《目标2》中，一种最先进的盘中软骨 模型系统的部署使蛋白质平衡网络靶向治疗Colla- 遗传病。结合机制研究阐明失调的胶原蛋白的生物化学。 动态平衡，这一目标的工作将为以蛋白质动态学为重点的新的治疗视角提供坚实的基础- 治疗胶原病。

Collagen is the most abundant protein in animals, constituting up to one-third of total protein in humans. As the major proteinaceous component of tissues ranging from bone and skin to cartilage and basement mem- branes, it constitutes the molecular scaffold for animal life. This ubiquitous protein is challenging for cells to produce, requiring highly coordinated intracellular processes of folding, assembly, and quality control. Owing to the hierarchical nature of collagenous extracellular matrices, the physical and biochemical properties of these tissues are fundamentally defined by these upstream, intracellular processes. Defects, whether genetic or oth- erwise, that are detrimental to any aspect of collagen proteostasis can impact cell health or function and propa- gate to extracellular matrices, leading to diseases known as the collagenopathies. Unfortunately, these dis- eases almost universally lack effective, disease-modifying therapies. Current therapeutic strategies for the collagenopathies focus on regenerative therapies, efforts to strengthen the extracellular matrix itself, or palliative care. None of these approaches aim to address the up- stream issue leading to disease: a failure to properly fold and quality control collagen molecules themselves. If the breakdown of collagen proteostasis could be effectively addressed, the downstream symptoms targeted by current clinical strategies would be alleviated. Indeed, proteostasis enhancement has proven remarkably effi- cacious in many other genetic disorders, including cystic fibrosis, but it has yet to make serious inroads in the collagenopathies. One obstacle is inadequate understanding of the critical decision points in the collagen pro- teostasis network. Another issue is the challenge of pre-clinical testing of proteostasis-targeted interventions in a disease that requires robust, yet biochemically amenable, tissue model systems for discovery efforts. This R01 proposal seeks to address these knowledge gaps, both identifying and elucidating key mech- anisms of intracellular folding and quality control and assessing the therapeutic potential of proteostasis net- work-targeted therapeutics in the collagenopathies. In Aim 1, the functions of the highly conserved procollagen N-glycan in promoting folding, enabling quality control, and identifying when folded procollagens are ready for secretion will be elucidated, via comprehensive work both in cells and in vivo that will reveal the molecular mechanisms of collagen glycoproteostasis. The expectation is demonstration that the long-ignored procollagen N-glycan is actually the critical fulcrum of collagen proteostasis. In Aim 2, a state-of-the-art cartilage-in-a-dish model system is deployed to enable robust testing of proteostasis network-targeted therapies for the colla- genopathies. Combined with mechanistic studies to elucidate the biochemistry of dysregulated collagen prote- ostasis, work in this Aim will provide a strong foundation for a new, proteostasis-focused perspective on treat- ing the collagenopathies.