The role of sphingosine kinase 2 in mitochondrial dysfunction and NAFLD

鞘氨醇激酶 2 在线粒体功能障碍和 NAFLD 中的作用

基本信息

批准号：
10607244
负责人：
Kaitlyn Georgene Jackson
金额：
$ 4.13万
依托单位：
VIRGINIA COMMONWEALTH UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-04-10 至 2027-04-09
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10607244
关键词：
Adenovirus Vector Adult Affect Anti-Inflammatory Agents Bile Acids Biochemical Biological Biology Cardiac Myocytes Cell Nucleus Cell physiology Cells Clinical Complex Data Disease Disease Progression Drug Targeting Evaluation Exhibits Exposure to FDA approved Fatty Liver Flow Cytometry Future Genes Genetic Transcription Goals Hepatic Hepatocyte Histone Deacetylase Inhibitor Human Immune Immune response In Vitro Incidence Inflammation Inflammatory Inflammatory Response Innate Immune Response Intervention Knockout Mice Knowledge Kupffer Cells Link Lipids Literature Liver Location Malignant Neoplasms Measures Mediator Membrane Potentials Metabolic Diseases Metabolic stress Metabolism Mitochondria Modeling Molecular Nuclear Ontology Oxidative Stress Palmitic Acids Pathogenesis Patients Pattern Peripheral Pharmacotherapy Population Prevalence Protein Isoforms Reactive Oxygen Species Regulation Reporting Risk Role Saturated Fatty Acids Signal Transduction Signaling Molecule Source Sphingolipids Sphingosine-1-Phosphate Receptor System Testing Up-Regulation Variant Wild Type Mouse complex IV cytochrome c cytochrome c oxidase cytokine end stage liver disease endoplasmic reticulum stress fatty acid oxidation hepatocyte injury immune cell infiltrate immunoregulation improved in vivo innovation lipid metabolism liver inflammation mitochondrial dysfunction mitochondrial membrane mouse model new therapeutic target non-alcoholic fatty liver disease nonalcoholic steatohepatitis novel novel therapeutic intervention overexpression pharmacologic prevent prohibitin protective effect response sphingosine 1-phosphate sphingosine kinase trafficking transcriptome sequencing western diet

项目摘要

Non-alcoholic fatty liver disease (NAFLD) is a fast-growing disease with no FDA-approved treatments. Numerous studies have linked NAFLD-associated hepatocyte lipotoxicity with mitochondrial dysfunction during the last few decades. Though the onset of inflammation that drives the progression from NAFL to NASH is considered multifactorial, damage-associated molecular patterns (DAMPs) and reactive oxygen species (ROS) released by injured hepatocytes are essential in activating Kupffer cells and promoting peripheral immune cell infiltration. Sphingolipids are biochemical signaling mediators and can regulate mitochondrial function in metabolic diseases, including NAFLD. Sphingosine-1-phosphate (S1P) is a well-studied molecule with dualistic roles in cell function, dependent on the location of the sphingosine kinase (SphK) isoforms, SphK1 and SphK2. While SphK1- generated cytosolic S1P signaling is thoroughly described in the literature, few studies assess the role of SphK2- derived S1P. SphK2 is localized to the cell nucleus and mitochondria. In the context of NAFLD, nuclear SphK2 is anti-inflammatory by inhibiting histone deacetylases (HDACs) and preventing the transcription of proinflammatory genes. In contrast, the role of SphK2 within the mitochondria is not well defined. Previous in vitro studies evaluated the effect of cytosolic S1P, rather than mitochondrial S1P, on mitochondrial function. While SphK2 function has been assessed in hepatocytes, these studies have only defined short-term effects of SphK2 on hepatic steatosis. Our long-term goal is to understand sphingolipid regulation and define the mechanisms that influence NAFLD disease progression. The central hypothesis of this application is that dysregulation of mitochondrial SphK2 promotes NAFLD disease progression. Two specific aims are proposed to test the hypothesis. Aim 1 examines the role of SphK2 in regulating mitochondrial function in hepatocytes under metabolic stress. We will determine if exposure to palmitic acid alters mitochondrial sphingolipid metabolism in hepatocytes and further assess the impact of SphK2 depletion on mitochondrial complex IV function and assembly in hepatocytes. Aim 2 determines the impact of hepatic SphK2 on modulating the immune response under metabolic stress. First, we will measure the ability of SphK2 depleted hepatocytes to induce cytokine synthesis in Kupffer cells. Second, we will use spectral flow cytometry to determine SphK2- dependent variations on the hepatic immune cell profile in the WDSW model. Lastly, we will use an adenoviral vector system to determine whether overexpressed hepatocyte SphK2 exhibits protective effects in NAFLD pathogenesis. To date, these functions of hepatocyte SphK2 have not been defined in the literature. Completing our proposed study will contribute to our understanding of SphK2 in hepatocyte mitochondrial function and highlight how SphK2 influences inflammation in NAFLD. Our novel findings are essential to fundamental hepatocyte biology and may influence future studies targeting sphingolipid signaling in developing innovative pharmacotherapies for NAFLD.

非酒精性脂肪肝病（NAFLD）是一种快速增长的疾病，没有FDA批准的治疗方法。很多的研究已将NAFLD相关的肝细胞脂肪毒性与线粒体功能障碍联系起来几十年。尽管驱动从NAFL发展到NASH的炎症发作被认为多因素，与损伤相关的分子模式（湿）和活性氧（ROS）释放损伤的肝细胞对于激活库普弗细胞和促进外周免疫细胞浸润至关重要。鞘脂是生化信号传导介质，可以调节代谢中的线粒体功能包括NAFLD在内的疾病。鞘氨氨酸1-磷酸（S1P）是一个精心研究的分子，在细胞中具有二元作用功能，取决于鞘氨醇激酶（SPHK）同工型，SPHK1和SPHK2的位置。而sphk1-- 在文献中彻底描述了产生的胞质S1P信号传导，很少有研究评估SPHK2-的作用。派生的S1P。 SPHK2位于细胞核和线粒体。在NAFLD的背景下，核sphk2 通过抑制组蛋白脱乙酰基酶（HDAC）并防止转录促炎基因。相比之下，SPHK2在线粒体中的作用尚未很好地定义。以前体外研究评估了胞质S1P而不是线粒体S1P对线粒体功能的影响。尽管已在肝细胞中评估了SPHK2功能，但这些研究仅定义了短期影响 Sphk2在肝脂肪变性上。我们的长期目标是了解鞘脂调节并定义影响NAFLD疾病进展的机制。该应用程序的中心假设是线粒体SPHK2的失调会促进NAFLD疾病的进展。两个具体目标是提议检验该假设。 AIM 1检查了SPHK2在调节线粒体功能中的作用肝细胞在代谢胁迫下。我们将确定暴露于棕榈酸是否改变线粒体肝细胞中的鞘脂代谢，并进一步评估SPHK2耗竭对线粒体的影响复杂的IV功能和肝细胞中的组装。 AIM 2确定肝SPHK2对调节的影响代谢应激下的免疫反应。首先，我们将测量SPHK2耗尽的肝细胞的能力诱导Kupffer细胞中的细胞因子合成。其次，我们将使用光谱流式细胞仪确定SPHK2- WDSW模型中肝免疫细胞谱的依赖性变化。最后，我们将使用腺病毒矢量系统确定过表达的肝细胞SPHK2是否在NAFLD中表现出保护作用发病。迄今为止，文献中尚未定义肝细胞SPHK2的这些功能。完成我们提出的研究将有助于我们在肝细胞线粒体功能中对SPHK2的理解和突出显示SPHK2如何影响NAFLD的炎症。我们的新颖发现对于基本来说至关重要肝细胞生物学，并可能影响针对鞘脂信号传导的未来研究 NAFLD的药物疗法。