Pathogenesis and Treatment of Liver Disease in Transaldolase Deficiency

转醛醇酶缺乏性肝病的发病机制和治疗

• 批准号: 8078182
• 负责人: Andras Perl
• 金额: $ 32.77万
• 依托单位: UPSTATE MEDICAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8078182
• 关键词: 4 hydroxynonenal; Acetaminophen; Acetylcysteine; Acute; Acute Liver Failure; Age; Aldehyde Reductase; Aminophenols; Animal Model; Antioxidants; Apoptosis; Blood donor; Cancer Etiology; Case Study; Caucasians; Caucasoid Race; Cause of Death; Cell Death; Cells; Cessation of life; Child; Chronic; Cirrhosis; Code; Defect; Development; Disease; Dysplasia; Enzymes; Exhibits; Failure; Fatty Liver; Fibroblasts; Gene Mutation; Genes; Genetic; Genomics; Glucose; Glucose-6-Phosphate; Glutathione; Hepatocarcinogenesis; Hepatocyte; Human; Human Cloning; In Vitro; Inflammation; Inflammatory; JUN gene; Link; Lipid Peroxides; Lipids; Liver; Liver Cirrhosis; Liver Failure; Liver diseases; Malignant Neoplasms; Malondialdehyde; Mediating; Membrane Potentials; Metabolic; Metabolic Pathway; Mitochondria; Molecular; Mus; Mutation; NADP; Overdose; Oxidation-Reduction; Oxidative Stress; Oxidoreductase; Pathogenesis; Pathway interactions; Patients; Pentosephosphate Pathway; Phase; Phosphogluconate Dehydrogenase; Phosphorylation; Play; Predisposition; Prevalence; Primary carcinoma of the liver cells; Production; Protein Dephosphorylation; Proteins; Recycling; Relative (related person); Resistance; Role; Secondary to; Siblings; Supplementation; TNFRSF6 gene; Testing; Tissues; Toxic effect; Transaldolase; Tylenol; alpha-Fetoproteins; base; cell type; computerized data processing; hepatoma cell; in vivo; inhibitor/antagonist; liver cell proliferation; lymphoblast; mitochondrial dysfunction; mortality; multicatalytic endopeptidase complex; neoplastic cell; neuronal cell body; non-alcoholic fatty liver; nonalcoholic steatohepatitis; novel; polyol; prevent; public health relevance; receptor; research study; ribose-5-phosphate; sedoheptulose 7-phosphate; sugar; transcription factor; tumor; young adult

DESCRIPTION (provided by applicant): Although oxidative stress is implicated in both acute acetaminophen-induced liver failure and chronic liver diseases, cirrhosis and hepatocellular carcinoma (HCC), no common underlying metabolic pathways have been identified. The preliminary results indicate that deficiency of transaldolase (TAL, encoded by the TALDO1 genomic locus), an enzyme of the pentose phosphate pathway (PPP), is an important cause of oxidative stress in the liver that predisposes to acetaminophen-induced liver failure and hepatocarcinogenesis. Recent case reports suggested a link of homozygous mutations in the TAL gene with liver failure and cirrhosis in children. In fibroblasts and lymphoblasts of the first TAL-deficient patient, we found that deletion of S171 caused mis- folding, proteasome-mediated degradation and complete deficiency of enzymatic activity. TAL deficiency resulted in accumulation of sedoheptulose 7-phoshate (S7P) and depletion of glucose 6-phoshate (G6P), indicating a failure to recycle ribose 5-phosphate (R5P) into G6P through the non-oxidative branch of the PPP, thus reducing NADPH production by the oxidative branch. This patient's cells exhibited mitochondrial dysfunction, increased susceptibility to H2O 2 and resistance to Fas apoptosis. To create an animal model of TAL deficiency, we inactivated the TALDO1 genomic locus in the mouse. Cirrhosis and nodular dysplasia were highly prevalent in mice with partial deficiency (TAL+/-; 62/229, 27.0%) or complete deficiency of TAL (TAL-/-; 77/97, 79.4%), relative to wild-type littermates (TAL+/+; 1/102, 1.0%). Cirrhosis invariably followed the formation of microvesicular and macrovesicular lipid droplets indicating nonalcoholic fatty liver disease (NAFLD) and inflammatory changes resembling non-alcoholic steatohepatitis (NASH). HCC was the leading cause of death in both TAL+/- (39/229; 17%) and TAL-/- mice (45/97; 46%) as compared to TAL+/+ littermates (1/102; 1%). Oxidative stress in TAL-deficient livers was characterized by the accumulation of S7P, failure to recycle R5P for the oxidative PPP, depleted NADPH and glutathione levels, and increased production of lipid hydroperoxides (LPO). Reduced 2-catenin phosphorylation and enhanced c-jun expression in TAL-/- livers reflected adaptation to oxidative stress. TAL-/- hepatocytes were resistant to CD95/Fas-mediated apoptosis in vitro and in vivo. Remarkably, lifelong administration of N-acetylcysteine (NAC) blocked acetaminophen susceptibility, restored Fas-dependent apoptosis, phosphorylation of 2-catenin, activation of c-jun and prevented the development of NASH, cirrhosis, and hepatocarcinogenesis in TAL-deficient mice. We also found an increased prevalence of TAL haploinsufficiency in human livers with cirrhosis and HCC. Thus, the preliminary studies identify TAL deficiency as a novel cause of liver cirrhosis and HCC which are preventable by lifelong supplementation of the potent antioxidant NAC. The proposed studies will test the hypothesis that TAL deficiency leads to oxidative stress, through diminished production of NADPH leading to secondary depletion of GSH that underlies the susceptibility of acetaminophen-induced liver failure and chronic liver disease, progressing from NAFLD to NASH, cirrhosis, and HCC. Under Specific Aim 1, we will determine the molecular mechanisms that cause NADPH depletion in TAL-deficient hepatocytes. Under Specific Aim 2, we will test the hypothesis that hepatocarcinogenesis of TAL-deficient mice is triggered by NADPH depletion- induced oxidative stress, mediated by the over-expression of aldose reductase (AR) and the activation of 2- catenin and c-jun, and prevented by post-natal treatment with N-acetylcysteine or AR blockade. Under Specific Aim 3, we will determine the prevalence and molecular basis of TAL deficiency in patients with acetaminophen-induced liver failure, NAFLD, NASH, cirrhosis and HCC. These studies will generate fundamental new information on the pathogenesis and treatment of liver disease. PUBLIC HEALTH RELEVANCE: Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer- related death worldwide. Acetaminophen (also known as Tylenol) overdose is the leading cause of acute liver failure in the US. Although oxidative stress has been implicated in HCC and acetaminophen toxicity, the genetic causes that predispose patients to these diseases are unknown. Recently, deficiency of transaldolase (TAL) was discovered in children with liver failure and cirrhosis. TAL is an enzyme that helps the utilization of the sugar glucose in certain cells of the body, such as liver cells, to produce and sustain normal levels of the compounds NADPH and glutathione which protect the integrity of the cells against oxidative stress. We created an animal model of TAL deficiency by a targeted genetic mutation in the mouse. Although mice partially (TAL+/-) or completely deficient of TAL (TAL-/-) develop normally, they are 27-fold and 79-fold more likely to develop cirrhosis and HCC than their siblings having normal TAL gene and activity. TAL-deficient (TAL-/-) mice are also more susceptible to acetaminophen-induced liver failure and death than their siblings carrying the normal TAL gene. Thus, the preliminary studies identify TAL deficiency as a novel cause of liver cirrhosis and HCC as well as acetaminophen-induced liver failure. We hypothesize that NADPH plays critical roles in the survival and multiplication of tumor cells in the liver. The proposed experiments will determine the mechanism of NADPH depletion, whether a correctable defect is responsible for the tumor-causing proliferation of liver cells, and examine the involvement of TAL deficiency in patients with acetaminophen- induced liver failure, fatty liver inflammation, cirrhosis and HCC. These studies should generate fundamental new information on the cause and treatment of potentially fatal diseases of the liver.

描述（由申请人提供）：尽管氧化应激与急性对乙酰氨基酚诱导的肝衰竭和慢性肝病，肝硬化和肝细胞癌癌（HCC）有关，但尚未鉴定出常见的基础代谢途径。初步结果表明，跨多溶解酶的缺乏（TAL，由TALDO1基因组基因座编码），一种五旬节磷酸途径（PPP）的酶，是肝脏中氧化应激的重要原因，易感性抗乙酰氨基酚诱导的肝衰竭和Hepatocarcincinosenosecon。最近的病例报告表明，TAL基因中的纯合突变与儿童的肝衰竭和肝硬化有关。在第一批TAL缺陷患者的成纤维细胞和淋巴细胞中，我们发现S171的缺失会导致错误折叠，蛋白酶体介导的降解和完全缺乏酶活性。 TAL缺乏症导致凝血蛋白7-磷酸盐（S7P）的积累和葡萄糖6-磷酸盐（G6P）的消耗，表明未能通过PPP的非氧化分支将5-磷酸核糖（R5P）恢复到G6P中，从而减少了NADPH生产，从而减少了NADPH的生产。该患者的细胞表现出线粒体功能障碍，增加了对H2O 2的敏感性以及对FAS凋亡的抗性。为了创建TAL缺乏症的动物模型，我们灭活了小鼠中的Taldo1基因组基因局基因局。肝硬化和结节性发育不良在部分缺乏的小鼠中高度流行（TAL +/-; 62/229，27.0％）或TAL（TAL - / - ; 77/ - ; 77/97，79.4％）的完全缺乏，相对于野生型同窝（TAL+/+; 1/102，102，102，1.0％）。肝硬化总是在形成微毛和大丝状脂质液滴之后，表明非酒精性脂肪肝病（NAFLD）以及类似于非酒精性脂肪性肝炎（NASH）的炎症变化。与TAL+/+同伙（1/102; 1％）相比，HCC是TAL +/-（39/229; 17％）和TAL - / - 小鼠（45/97; 46％）的主要死亡原因。 TAL缺陷肝脏中的氧化应激的特征是S7P的积累，氧化PPP的R5P未能再利用R5P，NADPH枯竭和谷胱甘肽水平以及脂质氢过氧化物（LPO）的产生增加。在TAL - / - 肝脏中降低了2-catenin磷酸化和增强的C-JUN表达，反映了对氧化应激的适应性。 TAL - / - 肝细胞在体外和体内对CD95/FAS介导的凋亡具有抗性。值得注意的是，终生给药N-乙酰半胱氨酸（NAC）阻断了乙酰氨基酚的敏感性，恢复了FAS依赖性凋亡，2-catenin的磷酸化，C-JUN的激活，并防止了NASH，CIRRHOSIS和CIRRHOSIS和HEPATOCARCINESONE的发展。我们还发现，肝硬化和HCC的人肝脏中TAL单倍体不足的患病率增加。因此，初步研究将TAL缺乏症视为肝硬化和HCC的新原因，可以通过补充有效的抗氧化剂NAC来预防。拟议的研究将通过减少NADPH的产生，导致GSH的继发性耗竭，这是对乙酰氨基酚诱导的肝衰竭和慢性肝病的易感性，从而导致TAL缺乏导致氧化应激的假设，从而从NAFLD到NAFLD，NAFLD，Cirrhosis和HCC。在特定的目标1下，我们将确定导致TAL缺陷型肝细胞中NADPH耗竭的分子机制。在特定的目标2下，我们将检验以下假设：NADPH耗竭诱导的氧化应激触发了TAL缺陷小鼠的肝癌发生，这是由醛糖还原酶（AR）的过表达介导的，并激活2-蛋白酶和C-Jun和C-Jun，并通过n-arbackade blocke blocke blocke cante nine-arbade block酸或预防。在特定的目标3下，我们将确定对乙酰氨基酚诱导的肝衰竭，NAFLD，NASH，CIRRHOSIS和HCC患者TAR缺乏症的患病率和分子基础。这些研究将产生有关肝病发病机理和治疗的基本新信息。 公共卫生相关性：肝细胞癌（HCC）是全球第五个最常见的癌症，也是与癌症相关死亡的第三大主要原因。对乙酰氨基酚（也称为泰诺）过量是美国急性肝衰竭的主要原因。尽管氧化应激与HCC和对乙酰氨基酚的毒性有关，但使患者患有这些疾病的遗传原因尚不清楚。最近，在患有肝衰竭和肝硬化的儿童中发现了跨道酶（TAL）的缺乏。 TAL是一种酶，有助于在人体某些细胞（例如肝细胞）中利用糖葡萄糖，以产生和维持正常水平的NADPH和谷胱甘肽，从而保护细胞的完整性免受氧化应激。我们通过小鼠中靶向的遗传突变创建了TAL缺乏的动物模型。尽管小鼠部分（TAL +/-）或完全缺乏TAL（TAL - / - ）正常发育，但与具有正常的TAL基因和活性的兄弟姐妹相比，它们发展肝硬化和HCC的可能性要高27倍和79倍。与携带正常TAL基因的兄弟姐妹相比，TAL缺陷（TAL - / - ）小鼠也更容易受到对乙酰氨基酚诱导的肝衰竭和死亡的影响。因此，初步研究将TAL缺乏症视为肝硬化和HCC以及对乙酰氨基酚诱导的肝衰竭的新原因。我们假设NADPH在肝脏中肿瘤细胞的存活和繁殖中起关键作用。提出的实验将确定NADPH耗竭的机制，是否校正缺陷是否导致肝细胞引起肿瘤的增殖，并检查TAL缺乏症在乙酰氨基酚诱导的肝衰竭，脂肪肝炎症，肝硬化和HCC患者中的参与。这些研究应产生有关肝脏潜在致命疾病的原因和治疗的基本新信息。