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Beta-catenin inhibition as a novel therapeutic strategy for porphyria

β-连环蛋白抑制作为卟啉症的新型治疗策略

基本信息

批准号：
10264151
负责人：
Kari N Nejak-Bowen
金额：
$ 43.52万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-15 至 2025-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10264151
关键词：
Acute Acute Intermittent Porphyria Address Affect Aminolevulinic Acid Appearance Autophagocytosis Cell physiology ChIP-seq Chemicals Clinical Defect Deferoxamine Deposition Diet Disease Disease Progression Enzymes Erythropoietic Protoporphyria Event Extrahepatic FRAP1 gene Gene Expression Genes Genetic Genetic Models Glutamate-Ammonia Ligase Glutamine Heme Hemin Hepatic Porphyrias Hepatobiliary Hepatocyte Human Hydroxymethylbilane Synthase Immunohistochemistry In Vitro Injury Knock-out Knockout Mice Ligase Liver Measures Medical Metabolic Diseases Modeling Mus Mutant Strains Mice Oxygenases Palliative Care Pathology Pathway interactions Patients Phenobarbital Phenotype Phototoxicity Porphobilinogen Synthase Porphyrias Porphyrins Production Protoporphyrins Rare Diseases Regulation Reporter Role Severities Signal Pathway Signal Transduction Site-Directed Mutagenesis Source Testing Tetrapyrroles Therapeutic Therapeutic Intervention Time Treatment Efficacy Validation WNT Signaling Pathway Work base beta catenin chromatin immunoprecipitation clinically relevant drug metabolism efficacy evaluation enzyme biosynthesis enzyme pathway ferrochelatase heme biosynthesis improved improved functioning in silico in vitro Assay inhibitor/antagonist liquid chromatography mass spectrometry liver injury mouse model novel novel therapeutic intervention patient subsets prevent promoter protein aggregation standard of care therapeutic development

项目摘要

The porphyrias are a group of metabolic disorders that are caused by defects in heme biosynthesis pathway enzymes, and liver is commonly either a source or target of excess porphyrins. Treatment for most of the porphyrias is limited, and often focused on symptomatic relief and palliative care. Thus, mechanistic-based studies that emphasize therapeutic development are desperately needed. Previous work has identified the Wnt/b-catenin signaling pathway as a modulatable target in the 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet-induced mouse model of porphyria. Inhibition of b-catenin in mice subjected to DDC results in a significant reduction in liver injury due to decreased porphyrin accumulation. We identified a network of key heme biosynthesis enzymes such as δ-aminolevulinic acid (ALA) synthetase and ALA-dehydratase that are suppressed in the absence of b-catenin, resulting in decreased production of porphyrin intermediates and DDC-associated protein aggregation. Autophagy is also increased in mice lacking b-catenin, which may further contribute to protection from injury. Thus, the overarching hypothesis of the proposal is that inhibiting Wnt/b-catenin signaling in clinically-relevant models of porphyria will alleviate injury and progression of disease through decreased production of porphyrin intermediates and/or increased autophagy. In aim 1, we will determine the most proximal step in the pathway that is affected by b-catenin inhibition by treating hepatocytes with ALA and measuring the appearance of porphyrin intermediates; investigate the mechanism by which b-catenin regulates heme enzymes through site-directed mutagenesis, in silico studies, and chromatin immunoprecipitation; and demonstrate therapeutic relevance of targeting β-catenin in patients by utilizing immunohistochemistry to correlate the extent of b-catenin expression with expression of heme enzymes. In aim 2, we will characterize the role and regulation of autophagy in porphyria after Wnt/b-catenin inhibition. We will use RFP-EGFP-LC3 mice, a pH-dependent fluorescent reporter strain, and a genetic knockout of glutamine synthetase, a component of the b-catenin/mTOR pathway, as well as in vitro assays, to comprehensively address the contribution of this cellular process to the observed protected phenotype. In aim 3, we will determine whether inhibiting b-catenin in genetic mouse models of porphyria decreases porphyrin accumulation and improves liver pathology. Two well-characterized porphyria models: the ferrochelatase (Fechm1Pas) mutant mice, which mimics human erythropoietic protoporphyria with significant liver involvement; and the T1/T2 mouse, which is compound heterozygous for hydroxymethylbilane synthase and mimics acute intermittent porphyria upon stimulation with phenobarbitol, will be utilized to determine whether therapeutic intervention with a b-catenin inhibitor can prevent progression or provide protection during acute attacks. Thus, the proposed studies will further our understanding of the potential for inhibiting b-catenin to treat porphyria, & will provide highly significant information for therapeutic and translational use.

卟啉症是一类由血红素生物合成途径缺陷引起的代谢性疾病