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.

项目总结 我们的长期目标是更好地定义协调红细胞生成的蛋白平衡途径，这是一种专门的 以大量合成血红蛋白和消除大多数其他蛋白质为特征的过程。这 应用程序研究蛋白质质量控制如何调节一种常见的血红素病--地中海贫血 由HBB基因突变导致的，该突变损害成人血红蛋白(HBA， α2？2)。因此，游离的α-珠蛋白形成细胞毒性沉淀物，导致成熟停滞和细胞凋亡 红系前体细胞(无效的红细胞生成)和溶血，导致贫血、骨骼畸形和铁 超载。目前的治疗方法包括红细胞输注、铁螯合和造血干细胞 对于选定的患者，移植是有效的，但并不是所有人都可以获得，特别是在中低收入者 这种疾病最流行的国家。因此，需要新的治疗方法。我们的初步数据 UNC-51样自噬激活蛋白1(ULK1)介导游离α珠蛋白的自噬 在贝氏-地中海贫血。一般来说，ULK1被雷帕霉素复合体1(MTORC1)的哺乳动物靶点抑制。 并受AMP激活的蛋白激酶(AMPK)刺激。MTORC1抑制剂的给药 雷帕霉素对HbbTh3/+小鼠的作用，一种经验证的贝型地中海贫血的临床前模型，刺激游离α- 珠蛋白以ULK1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 中心性假说：抑制mTORC1或激活AMPK可缓解？ 通过刺激ULK1介导的自噬清除游离α-珠蛋白而导致的地中海贫血。我们将通过以下方式进行测试：目标1， 优化mTORC1对HbbTh3/+小鼠ULK1激活的药理抑制作用 小鼠和人的α-珠蛋白自噬调节回路；目的2，测定 已知的mTORc1激活剂-元素铁是否抑制ULK1介导的α-珠蛋白清除 地中海贫血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， β-地中海贫血与高表达红系miR-451基因相互作用的研究 我们发现的microRNA对LKB1激酶及其底物AMPK有抑制作用。为支持目标3，中断 HbbTh3/+小鼠体内的双顺反子miR-144/451基因座导致α-珠蛋白沉淀物减少，并导致β-地中海贫血 病理学。总体而言，我们的研究有望阐明维持平衡的蛋白质平衡网络的生物学。 通过靶向蛋白降解合成血红蛋白并验证mTORC1、AMPK和ULK1作为 “可用药的”新的地贫疗法的靶点。