Novel role of RIPK3-dependent necroptosis pathway in lung and kidney fibrosis

摘要 纤维化是器官(如肺、肾)的致病过程，涉及细胞外过度沉积。 基质(ECM)导致器官动态平衡的丧失。纤维化是进行性慢性肾脏的标志 疾病是一种常见的对损伤的致病反应。同样，终末期肺部疾病通常 以肺纤维化为特征。最近的研究表明，坏死性下垂是一种遗传编程的细胞形式 受受体相互作用蛋白-1和-3(RIPK1，RIPK3)激酶调控的死亡可能已经出现 在人类疾病中的重要意义。目前对RIPK3在器官发病机制中的作用知之甚少 纤维化症。我们有令人兴奋的初步数据，RIPK3可以在实验模型中发挥关键功能 肾脏和肺纤维化。有趣的是，缺乏RIPK3的小鼠，但在其信号转导方面却没有针对混合 系谱激酶域样蛋白(MLKL)，可预防肾脏纤维化。我们还确认了 RIPK3介导的信号通路通过激活三磷酸腺苷调节脂肪酸代谢 裂解酶(ACL)，并促进肾脏纤维化。相比之下，缺乏RIPK3或MLKL的小鼠 容易患上肺纤维化。这些研究表明，RIPK3可能代表了一种新的介体。 器官纤维化，具有不同的器官或组织特异性效应。 内源性气体分子一氧化碳(CO)被认为是一种实验性的 器官损伤的治疗方式。我们发表的研究表明，生理性低剂量的一氧化碳可以缓解 单侧输尿管梗阻(UUO)诱导的肾纤维化和博莱霉素(BLM)诱导的肾纤维化 肺纤维化。因此，我们假设RIPK3是器官纤维化的重要介质。 通过MLKL非依赖和MLKL依赖的途径。依赖RIPK3(不依赖MLKL) 信号通路和FA合成通路的下游调控参与了糖尿病的发生发展 肾脏纤维化。相反，依赖RIPK3和MLKL的途径可以抑制肺纤维化。此外， 我们假设，CO通过靶向RIPK3和/或FA-3来保护多器官纤维化。 依赖的路径。RIPK3和/或FA生物合成蛋白可能作为诊断生物标记物 预测器官纤维化的严重程度和CO治疗的疗效。我们将在 特定目标：特定目标1：研究RIPK3和MLKL在发病机制中的作用 特定目标2：确定RIPK3调节的脂肪酸(FA)的致病作用 纤维化器官中的合成；特定目标3：确定RIPK3和FA合成途径的作用 CO对实验性肺和肾纤维化以及人类纤维化的治疗作用。

Abstract Fibrosis is a pathogenic process in organs (e.g., lung, kidney) involving the excess deposition of extracellular matrix (ECM) leading to loss of organ homeostasis. Fibrosis is the hallmark of progressive chronic kidney diseases as a common pathogenic response to injury. Similarly, end-stage lung diseases are often characterized by lung fibrosis. Recent studies suggest that necroptosis, a genetically-programmed form of cell death that is regulated by receptor-interacting protein-1 and -3 (RIPK1, RIPK3) kinases, may have emerging significance in human disease. Little is currently known of the role of RIPK3 in the pathogenesis of organ fibrosis. We have exciting preliminary data that RIPK3 can exert crucial functions in experimental models of kidney and lung fibrosis. Intriguingly, mice deficient in RIPK3, but not in its signaling target the mixed lineage kinase domain-like protein (MLKL), were protected against kidney fibrosis. We have also identified a RIPK3-mediated signaling pathway that regulates fatty acid (FA) metabolism by activating ATP citrate lyase (ACL), and contributes to kidney fibrosis. In contrast, mice deficient in either RIPK3 or MLKL were susceptible to pulmonary fibrosis. These studies suggest that RIPK3 may represent a novel mediator of organ fibrosis with differential organ or tissue-specific effects. The endogenous gaseous molecule carbon monoxide (CO) has been implicated as an experimental therapeutic modality in organ injury. Our published studies indicate that physiologic low-dose CO can mitigate fibrosis in unilateral ureteral obstruction (UUO)-induced kidney fibrosis, and in bleomycin (BLM)-induced pulmonary fibrosis. Therefore, we hypothesize that RIPK3 represents an important mediator of organ fibrosis through MLKL-independent and MLKL–dependent pathways. A RIPK3-dependent (MLKL-independent) signaling pathway and downstream regulation of the FA synthesis pathway contributes to the development of kidney fibrosis. In contrast, a RIPK3 and MLKL dependent pathway can inhibit pulmonary fibrosis. Moreover, we hypothesize that CO confers protection against multi-organ fibrosis by targeting either RIPK3 and/or FA- dependent pathways. RIPK3 and/or FA-biosynthetic proteins potentially serve as diagnostic biomarkers in predicting the severity of organ fibrosis and the efficacy of CO therapy. We will test these hypotheses in the following Specific Aims: Specific Aim 1: To characterize the function of RIPK3 and MLKL in the pathogenesis of organ fibrosis; Specific Aim 2: To determine the pathogenic contribution of RIPK3-regulated fatty acid (FA) synthesis in fibrotic organs; Specific Aim 3: To determine the role of the RIPK3 and the FA synthesis pathways in the therapeutic effects of CO in experimental lung and kidney fibrosis, and in human fibrosis.