ULK-mediated autophagy of α-globin in ß-thalassemia

α-地中海贫血中 ULK 介导的 α-珠蛋白自噬

• 批准号: 10539754
• 负责人: Mitchell J Weiss
• 金额: $ 65.26万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10539754
• 关键词: 5' -AMP-activated protein kinase; Adult; Affect; Alleles; Anemia; Apoptosis; Attenuated; Autophagocytosis; Biological Markers; Biology; CD34 gene; Cell Line; Cells; Chronic; Complex; Data; Deformity; Disease; Dose; Erythroblasts; Erythrocyte Transfusion; Erythrocytes; Erythroid; Erythroid Cells; Erythropoiesis; FRAP1 gene; Functional disorder; Gene Mutation; Genetic; Globin; Goals; Hematological Disease; Hematopoietic Stem Cell Transplantation; Hematopoietic stem cells; Hemoglobin; Hemoglobinopathies; Hemolysis; Human; Impairment; In Vitro; Iron; Iron Chelation; Iron Overload; Life; Mediating; Messenger RNA; MicroRNAs; Mus; Newborn Infant; Oxygen; Pathology; Pathway interactions; Patients; Pharmacology; Phosphotransferases; Pre-Clinical Model; Process; Production; Protein Kinase; Proteins; Quality Control; Regulation; Reporting; Repression; STK11 gene; Severities; Sickle Cell Trait; Sirolimus; Testing; Thalassemia; Therapeutic; Therapeutic Effect; Translating; Transplantation; alpha Globin; base; beta Globin; beta Thalassemia; bone; cofactor; cytotoxic; hepcidin; improved; in vivo; inhibitor; innovation; insight; low and middle-income countries; mimetics; new therapeutic target; novel therapeutics; prevent; protein aggregation; protein degradation; proteostasis; response; treatment strategy

PROJECT SUMMARY Our long-term goal is to better define the proteostasis pathways that coordinate erythropoiesis, a specialized process distinguished by massive hemoglobin synthesis and the elimination of most other proteins. This application investigates how protein quality control modulates ß-thalassemia, a common hemoglobinopathy caused by HBB gene mutations that impair the production of the ß-globin subunit of adult hemoglobin (HbA, α2ß2). Consequently, free α-globin forms cytotoxic precipitates that cause maturation arrest and apoptosis of erythroid precursors (ineffective erythropoiesis) and hemolysis, leading to anemia, bone deformities and iron overload. Current therapies, including red blood cell transfusion, iron chelation and hematopoietic stem cell transplantation for selected patients, are effective but not uniformly available, particularly in low/middle income countries where the disease is most prevalent. Hence, new therapies are needed. Our preliminary data demonstrate that the Unc-51–like autophagy activating kinase 1 (ULK1) mediates the autophagy of free α-globin in ß-thalassemia. In general, ULK1 is inhibited by the mammalian target of rapamycin complex 1 (mTORC1) kinase and stimulated by AMP-activated protein kinase (AMPK). Administration of the mTORC1 inhibitor rapamycin to HbbTh3/+ mice, a validated preclinical model for ß-thalassemia, stimulated the autophagy of free α- globin to reduce ineffective erythropoiesis and hemolysis in an ULK1-dependent fashion. Our data support the central hypothesis that mTORC1 inhibition or AMPK activation can alleviate the pathophysiology of ß- thalassemia by stimulating ULK1-mediated autophagic clearance of free α-globin. We will test this by: Aim 1, optimizing the pharmacological inhibition of mTORC1 for ULK1 activation in HbbTh3/+ mice and by defining the regulatory circuitry of α-globin autophagy in mouse and human ß-thalassemic erythroblasts; Aim 2, determining whether elemental iron, a known activator of mTORC1, suppresses ULK1-mediated clearance of α-globin in ß- thalassemic erythroblasts and whether this deleterious effect can be prevented by iron restriction; and Aim 3, elucidating the genetic interactions between ß-thalassemia and miR-451, an abundantly expressed erythroid microRNA that we showed to inhibit the LKB1 kinase and its substrate AMPK. In support of Aim 3, disruption of the bi-cistronic miR-144/451 locus in HbbTh3/+ mice caused a reduction in α-globin precipitates and ß-thalassemia pathologies. Overall, our studies promise to elucidate the biology of proteostasis networks that maintain balanced hemoglobin synthesis through targeted protein degradation and validate mTORC1, AMPK and ULK1 as “druggable” targets for novel ß-thalassemia therapies.

项目摘要 我们的长期目标是更好地确定协调红细胞生成的蛋白质稳态途径， 以大量血红蛋白的合成和大多数其他蛋白质的消除为特征的过程。这 应用研究了蛋白质质量控制如何调节β-地中海贫血，一种常见的血红蛋白病 由HBB基因突变引起，该突变损害成人血红蛋白的β-珠蛋白亚基（HbA， α 2 β 2）。因此，游离的α-珠蛋白形成细胞毒性沉淀，引起成熟停滞和细胞凋亡。 红系前体细胞（无效红细胞生成）和溶血，导致贫血、骨畸形和铁 超载。目前的治疗，包括红细胞输注，铁螯合和造血干细胞 为选定的患者进行移植是有效的，但并不统一，特别是在低/中等收入国家 这种疾病最流行的国家。因此，需要新的疗法。我们的初步数据 证明Unc-51样自噬激活激酶1（ULK 1）介导游离α-珠蛋白的自噬 β-地中海贫血。通常，ULK 1被雷帕霉素复合物1的哺乳动物靶蛋白（mTORC 1）抑制。 激酶和AMP激活的蛋白激酶（AMPK）刺激。mTORC 1抑制剂的给药 雷帕霉素对HbbTh 3/+小鼠（一种经验证的β-地中海贫血临床前模型）的作用，刺激了游离α- 珠蛋白以ULK 1依赖的方式减少无效的红细胞生成和溶血。我们的数据支持这一 中心假设mTORC 1抑制或AMPK激活可以减轻糖尿病的病理生理学， 通过刺激ULK 1介导的游离α-珠蛋白的自噬清除而导致地中海贫血。我们将通过以下方式进行测试：目标1， 优化HbbTh 3/+小鼠中mTORC 1对ULK 1激活的药理学抑制，并通过定义 小鼠和人类α-地中海贫血成红细胞中α-珠蛋白自噬的调节回路;目的2，确定 是否元素铁，一种已知的mTORC 1激活剂，抑制ULK 1介导的α-珠蛋白在β-珠蛋白中的清除， 地中海贫血成红细胞以及这种有害影响是否可以通过限制铁来预防;以及目标3， 阐明β-地中海贫血和miR-451之间的遗传相互作用， 我们发现microRNA抑制LKB 1激酶及其底物AMPK。为了支持目标3， HbbTh 3/+小鼠中的双顺反子miR-144/451基因座导致α-珠蛋白沉淀物和β-地中海贫血减少 病理学总的来说，我们的研究有望阐明维持平衡的蛋白质稳态网络的生物学。 通过靶向蛋白质降解进行血红蛋白合成，并验证mTORC 1、AMPK和ULK 1作为 新型β-地中海贫血疗法的“可药物化”靶点。