Interaction of fibroblasts with cell corpses increases collagen synthesis during lung repair

项目总结 损伤后的修复是一个基本的生物过程，对维持肺健康至关重要。成纤维细胞必须 在损伤后执行关键的促修复功能，包括增殖和合成新的细胞外基质， 尤其是胶原蛋白，那种脚手架伤口闭合。产生死亡细胞(统称为细胞身体) 在肺损伤和炎症期间，并已被证明促进从炎症到修复的转变。 先前的研究主要集中在了解巨噬细胞与凋亡身体的相互作用。然而，非- 包括成纤维细胞在内的专业吞噬细胞也可以与细胞身体相互作用，其后果是 肺内的相互作用还没有研究过。这项提案旨在解决有关成纤维细胞的未知问题- 身体相互作用及其在健康肺修复中的作用。我们发现，细胞身体的识别 成纤维细胞使成纤维细胞增加胶原蛋白的合成。我们的初步数据支持一种机制 其中磷脂酰丝氨酸受体Axl结合细胞身体，激活多胺代谢物合成， 增加细胞内的亚精胺水平，这会助长激素化。亚低温发生在一种单一的蛋白质上： 核糖体亚基eiF5a。当被激活时，eiF5a能够稳定多聚脯氨酸重复蛋白的翻译 包括胶原蛋白。亚低温对细胞增殖也很重要。阻止多胺合成 身体识别反应中eiF5a的激活。阻断Ax1或Hythusine-eiF5a可阻止这种增加 在胶原蛋白中对身体识别做出反应。我们还表明，在体内，苏氨酸-eiF5a在 肺损伤后的成纤维细胞，胶原沉积和肺泡毛细血管修复减少 用抑制剂GC7或通过靶向删除激活酶来阻断激动剂的作用 成纤维细胞中的脱氧亚硫氨酸合成酶。这导致我们假设成纤维细胞与细胞身体的相互作用 是激活肺损伤后成纤维细胞增殖和胶原合成的中心信号，促进 修理。我们将使用三个目标来测试1)通过AXL识别身体是否触发翻译调控的增加 在胶原蛋白中，身体识别驱动多胺合成，从而增加亚精胺的合成 苏氨酸-eiF5a和稳定胶原翻译，以及3)充分激活促修复编程成纤维细胞 需要能够通过Axl感知身体，通过鸟氨酸脱羧酶合成多胺，以及苏木精 在肺损伤后，eiF5a通过脱氧亚硫氨酸合成酶来增殖和合成新的细胞外基质。

PROJECT SUMMARY Repair after injury is a fundamental biologic process that is critical for maintaining lung health. Fibroblasts must perform key pro-repair functions after injury including proliferation and synthesis of new extracellular matrix, particularly collagens, that scaffold wound closure. Dead cells (collectively termed cell corpses) are produced during lung injury and inflammation and have been shown to promote the transition from inflammation to repair. Prior research has focused on understanding macrophage interactions with apoptotic corpses. However, non- professional phagocytes including fibroblasts can also interact with cell corpses and the consequence of these interactions in the lung has not been studied. This proposal seeks to address unknowns regarding fibroblast- corpse interactions and their role in healthy lung repair. We have found that recognition of cell corpses by fibroblasts causes fibroblasts to increase collagen protein synthesis. Our preliminary data support a mechanism where the phosphatidylserine receptor Axl binds cells corpses, activates polyamine metabolite synthesis, increasing intracellular spermidine levels, which fuel hypusination. Hypusination occurs on a single protein: the ribosomal subunit eiF5a. When hypusinated, eiF5a is able to stabilize translation of poly-proline-repeat proteins including collagen. Hypusination is also important for cell proliferation. Blocking polyamine synthesis prevented hypusination of eiF5a in response to corpse recognition. Blocking Axl or hypusine-eiF5a prevented the increase in collagen in response to corpse recognition. We also show that, in vivo, hypusine-eiF5a is increased in fibroblasts after lung injury and that collagen deposition and alveolar-capillary repair are reduced when hypusination is blocked with the inhibitor GC7 or through targeted deletion of the hypusination enzyme deoxyhypusine synthase in fibroblasts. This led us to hypothesize that interaction of fibroblasts with cell corpses is a central cue that activates fibroblast proliferation and collagen synthesis following lung injury, facilitating repair. We will use three aims to test if 1) corpse recognition via Axl triggers a translationally-regulated increase in collagen protein, 2) corpse recognition drives polyamine synthesis that increases spermidine that increases hypusine-eiF5a and stabilizes collagen translation, and 3) to fully activate pro-repair programming fibroblasts require the ability to sense corpses via Axl, synthesize polyamines via ornithine decarboxylase, and hypusinate eiF5a via deoxyhypusine synthase in order to proliferate and synthesize new extracellular matrix after lung injury.