Metabolic regulation of fibroblast fate by ATP citrate lyase

项目摘要 特发性肺纤维化（IPF）是一种以进行性累积为特征的纤维化肺部疾病 纤维化细胞外基质（ECM）最终导致广泛的气道重塑，肺功能受损 和呼吸衰竭负责大多数ECM产生的细胞类型是活化的成纤维细胞 称为肌成纤维细胞，其特征在于α-SMA表达和ECM蛋白的产生，特别是 胶原和纤连蛋白。我们的实验室先前已经证明，年轻的老鼠能够 自发解决博莱霉素诱导的肺纤维化，肌成纤维细胞群经历了 凋亡和清除;相反，老年小鼠未能解决与持久性肌成纤维细胞 似乎对凋亡具有抗性的群体。 ATP柠檬酸裂解酶（ACLY）是催化柠檬酸盐转化为乙酰辅酶A的酶，从而 调节乙酰辅酶A生物利用度和脂肪酸合成。查询公开可用的数据集 表明在患有IPF的人类受试者的肺中ACLY mRNA水平降低。我们的初步数据显示 年龄超过18个月的小鼠中的ACLY表达也是缺乏的，并且当 使其经受博来霉素诱导的纤维化。IMR 90人成纤维细胞中的ACLY siRNA敲低促进 肌成纤维细胞标志物α-SMA的产生下调AMPK的磷酸化， 肌成纤维细胞凋亡抵抗。本项目提案将测试ACLY缺陷驱动 肌成纤维细胞凋亡调控，并确定ACLY是否是一个治疗目标，在小鼠模型中， 持续性肺纤维化目的1研究ACLY在肌成纤维细胞分化过程中的调控， 与TGF-β1的相互作用。目的2将重点阐述ACLY调控细胞凋亡的机制， 特别是对AMPK磷酸化的影响。Aim 3将利用基因敲除小鼠模型， 明确检查ACLY缺乏症是否是能够维持持续性纤维化的关键纤维化驱动因素。 总之，这些研究将阐明ACLY在纤维化和非消退性持续性肺纤维化中的作用 同时也作为塞缪尔·史密斯（PI）研究培训的坚实基础的工具， 导师维克托Thannickal博士，促进他的专业发展，并促进他的途径， 独立的学术研究。

Project Summary Idiopathic Pulmonary Fibrosis (IPF) is a fibrotic lung disease characterized by progressive accumulation of fibrotic extracellular matrix (ECM) eventually leading to extensive airway remodeling, impaired lung function and respiratory failure. The cell type responsible for the majority of ECM production is an activated fibroblast known as the myofibroblast, characterized by α-SMA expression and production of ECM proteins, particularly collagen and fibronectin. Our laboratory has previously demonstrated that young mice are capable of spontaneously resolving bleomycin induced lung fibrosis, with the myofibroblast population undergoing apoptosis and clearance; in contrast, aged mice fail to resolve in association with a persistent myofibroblast population that appears to be resistant to apoptosis. ATP Citrate Lyase (ACLY) is an enzyme which catalyzes citrate to acetyl CoA conversion, thereby regulating acetyl-CoA bioavailability and fatty acid synthesis. Interrogation of a publicly available dataset indicates that ACLY mRNA levels are reduced in lungs of human subjects with IPF. Our preliminary data shows that ACLY expression in mice aged over 18 months is also deficient and that this expression decreases when subjected to bleomycin induced fibrogenesis. ACLY siRNA knockdown in IMR90 human fibroblasts promotes production of α-SMA, a myofibroblast marker, downregulates phosphorylation of AMPK and enhances myofibroblast apoptosis resistance. This project proposal will test the hypothesis that ACLY deficiency drives myofibroblast apoptosis regulation and determine whether ACLY is a therapeutic target in a mouse model of persistent lung fibrosis. Aim 1 will investigate ACLY regulation during myofibroblast differentiation, particularly its interaction with TGF-β1. Aim 2 will focus describing the mechanism of apoptotic regulation by ACLY, especially on its effects on AMPK phosphorylation. Aim 3 will make use of a genetic knockout mouse model to definitively examine whether ACLY deficiency is a key fibrotic driver capable of sustaining persistent fibrosis. Collectively these studies will elucidate the role ACLY in fibrogenesis and non-resolving persistent lung fibrosis while also serving as the vehicle for a solid foundation of research training for Samuel Smith (PI) under the mentorship of Dr. Victor Thannickal, fostering his professional development and facilitating his pathway to independent academic research.