Mannose metabolism as a regulator of hepatic stellate cell activation and fibrosis

项目摘要 甘露糖代谢作为肝星状细胞活化和纤维化的调节剂 该提案通过阐明一种新的抗纤维化治疗方法， 肝星状细胞（HSC）是一种常驻窦周细胞类型， 储存维生素A的细胞然而，在驱动HSC可塑性的潜在机制中，糖 代谢途径在很大程度上被忽视。甘露糖代谢在HSC生物学中的作用还没有得到证实。 还没有被检查，但最近的高影响力的研究，包括我们的（Shtraizent和DeRossi等人，eLife 2017）， 涉及甘露糖作为肥胖、糖尿病和癌症介质。甘露糖磷酸异构酶（MPI）是 参与甘露糖分解的关键酶;人类MPI突变导致先天性N- 在儿童中以早期和进行性肝纤维化为特征的糖基化。我们的数据和这些临床 这些观察刺激我们探索这种儿科疾病中MPI的丧失如何导致肝纤维化。我们 令人兴奋的数据发现：1）在啮齿动物和斑马鱼体内HSC活化和纤维化期间MPI降低， 2)MPI降低与人类HBV和NAFLD队列中肝纤维化的晚期相关，以及3） MPI耗竭促进人HSC中的HSC活化。值得注意的是，补充甘露糖 HSC活化呈剂量依赖性。我们的目标是了解甘露糖的调节作用 HSC代谢和肝纤维化。为了达到以下目的，我们将检验我们的中心假设， 甘露糖代谢是介导HSC活化和衰减的关键代谢途径。 甘露糖代谢的破坏，通过MPI的损失，导致HSC活化;相反， 外源性甘露糖补充可在体内减弱HSC活化和肝纤维化。具体 目标：目标1。确定MPI缺失如何激活HSC：通过使用原代大鼠HSC和体内遗传学方法， 斑马鱼模型，我们将研究O-GlcNAc化在HSC活化中的作用，确定细胞特异性 MPI耗竭的影响，并测试增强MPI活性是否可以减弱 暴露于公认的HSC活化剂。目标二。确定甘露糖补充剂在 在体外和体内减弱HSC活化。该目的将使用体内啮齿动物纤维化模型来研究 补充甘露糖如何调节HSC表型的可塑性，并测试甘露糖对HSC表型的影响程度。 减轻体内肝纤维化。我们的长期目标是更好地了解HSC的代谢驱动因素 激活以操纵这些燃料产生机制并减弱肝纤维化。我们将利用我们 罕见肝病生物学方面的专业知识，以促进我们对HSC代谢调节的理解 激活，并建立这种被忽视的甘露糖代谢途径如何调节HSC的可塑性。 这些研究是第一次调查甘露糖补充剂的抗纤维化作用，并可能揭示 新的靶点和可获得的治疗方法来抑制肝纤维化。

PROJECT SUMMARY Mannose metabolism as a regulator of hepatic stellate cell activation and fibrosis This proposal addresses the critical unmet need for effective anti-fibrotic therapies by elucidating an unexplored pathway regulating activation of the hepatic stellate cell (HSC), a resident perisinusoidal cell type that stores vitamin A in normal liver. However, among potential mechanisms driving HSC plasticity, sugar metabolism pathways have been largely overlooked. The role of mannose metabolism in HSC biology has not yet been examined, but recent high-impact studies, including ours (Shtraizent and DeRossi et al., eLife 2017), implicate mannose as a mediator of obesity, diabetes, and cancer. Mannose phosphate isomerase (MPI) is the key enzyme involved in catabolism of mannose; MPI mutation in humans leads to a congenital disorder of N- glycosylation characterized by early and progressive liver fibrosis in children. Our data and these clinical observations stimulated us to explore how the loss of MPI in this pediatric disorder leads to liver fibrosis. Our exciting data find that: 1) MPI is decreased during HSC activation and fibrosis in rodents and zebrafish in vivo, 2) decreased MPI correlates with advanced stages of liver fibrosis in human HBV and NAFLD cohorts, and 3) MPI depletion promotes HSC activation in human HSCs. Remarkably, mannose supplementation attenuates HSC activation in a dose-dependent manner. Our objective is to understand the regulatory role of mannose metabolism in HSCs and liver fibrosis. With the following aims, we will test our central hypotheses that mannose metabolism is a critical metabolic pathway mediating HSC activation and attenuation. Disruption of mannose metabolism, through loss of MPI, leads to HSC activation; conversely, exogeneous mannose supplementation can attenuate HSC activation and liver fibrosis in vivo. Specific Aims: Aim 1. Determine how MPI loss activates HSCs: By using primary rat HSCs and in vivo genetic zebrafish models, we will investigate the role of O-GlcNAcylation in HSC activation, determine the cell-specific effects of MPI-depletion, and test whether enhancing MPI activity can attenuate fibrogenesis following exposure to well-established HSC activators. Aim 2. Determine the efficacy of mannose supplementation in attenuating HSC activation in vitro and in vivo. This aim will use in vivo rodent models of fibrosis to investigate how mannose supplementation modulates the plasticity of HSC phenotypes and test the extent of mannose to attenuate liver fibrosis in vivo. Our long-term goal is to better understand the metabolic drivers of HSC activation to manipulate these fuel-generating mechanisms and attenuate liver fibrosis. We will leverage our expertise in the biology of a rare liver disease to advance our understanding of the metabolic regulation of HSC activation, and to establish how this overlooked pathway of mannose metabolism can regulate HSC plasticity. These studies are the first to investigate the antifibrotic roles of mannose supplementation and may reveal a novel target and accessible therapeutic approach to suppress liver fibrosis.