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

项目总结 这项建议解决了有效的抗纤维化疗法尚未得到满足的关键需求，通过阐明一种未探索的 调节肝星状细胞(HSC)激活的途径，HSC是一种驻留在肝窦周围的细胞类型，它储存 正常肝脏中的维生素A。然而，在推动HSC可塑性的潜在机制中，糖 代谢 路径在很大程度上被忽视了。甘露糖代谢在肝星状细胞生物学中的作用 检查过，但最近的高影响研究，包括我们的(Shtraizent和DeRossi等人，eLife 2017)，涉及 甘露糖是肥胖、糖尿病和癌症的中介物。甘露糖磷酸异构酶(MPI)是 参与甘露糖分解代谢的酶 糖基化 人类基因突变导致先天N基因紊乱 以儿童早期和进行性肝纤维化为特征。我们的数据和这些临床 观察促使我们探索MPI在这种儿科疾病中的丢失是如何导致肝纤维化的。我们的 令人兴奋的数据发现：1)在原代人类和啮齿动物的HSC激活过程中，MPI表达下调 体内和体外的HSCs，2)MPI降低与人乙肝病毒肝纤维化晚期和 3)MPI缺失可促进人HSC的激活。值得注意的是，甘露糖 补充剂以剂量依赖的方式减弱HSC的激活。我们的目标是了解 甘露糖代谢在肝星状细胞和肝纤维化中的调节作用。有了以下目标，我们将测试我们的 甘露糖代谢是调节肝星状细胞活化的关键代谢途径的中心假设 和衰减。通过MPI的丢失破坏甘露糖代谢，导致HSC激活； 相反，外源性补充甘露糖可减轻HSC活化和肝纤维化。 活着。具体目标：目的1.确定MPI缺失如何激活HSCs：使用原代大鼠HSCs和在体内 在斑马鱼遗传模型中，我们将研究O-GlcN酰化在HSC激活中的作用，确定细胞- MPI-耗竭的特异性效应，并测试增强MPI活性是否可以减轻以下纤维化 接触成熟的HSC激活剂。目的2.测定补充甘露糖的疗效 降低体内、体外HSC活性。这一目标将使用体内的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 体内抗肝纤维化作用。我们的长期目标是更好地了解HSC激活的代谢驱动因素 操纵这些燃料生成机制，减轻肝纤维化。我们 这个 和 是 将利用我们的专业知识在 一种罕见肝病的生物学为了促进我们对HSC激活的代谢调节的理解， 以确定这一被忽视的甘露糖代谢途径如何调节HSC的可塑性。这些研究 首次研究甘露糖补充剂的抗纤维化作用，并可能揭示一个新的靶点和 可获得抑制肝纤维化的治疗方法。

PROJECT SUMMARY 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 glycosylation mutation in humans leads to a congenital disorder of N- 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 expression is downregulated during HSC activation in primary human and rodent HSCs in vitro and 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 the and are will leverage our expertise in biology of a rare liver disease to advance our understanding of the metabolic regulation of HSC activation, to establish how this overlooked pathway of mannose metabolism can regulate HSC plasticity. These studies the first to investigate the antifibrotic roles of mannose supplementation andmay reveal a novel target and accessible therapeutic approach to suppress liver fibrosis.