Mutations in AMBRA1 aggravate β-thalassemia by impairing autophagy-mediated clearance of free α-globin

作者：Yong Long, Qianqian Zhang, Ling Ling, Yuan Zhuang, Xiaolei Wei, Haoyang Huang, Zhanping Lu, Yu-Shan Huang, Xianming Chen, Yuhua Ye, Xiaoqin Feng, Haokun hao Zhang, Binbin Huang, Yueyan Huang, Yidan Liang, Mingyan Fang, Yukio Nakamura, Bin Lin, Xinhua Zhang, Daru Lu, Xin Jin, Xiangmin Xu · 发表于：Blood · 年份：2024 · DOI：10.1182/blood.2023022688 · 被引用次数：4 · 研究领域：Hemoglobinopathies and Related Disorders、Iron Metabolism and Disorders、Cannabis and Cannabinoid Research

ABSTRACT: Accumulation of free α-globin is a critical factor in the pathogenesis of β-thalassemia. Autophagy plays a crucial role in clearing toxic free α-globin, thereby reducing disease severity. However, the impact of natural mutations in autophagy-related genes (ATGs) on the phenotypic variability of β-thalassemia remains unclear. In this study, we systematically investigated the relationship between variants in ATGs and disease phenotypes in a cohort of 1022 patients with β-thalassemia, identifying 4 missense mutations in the autophagy and beclin 1 regulator 1 (AMBRA1) gene. Disruption of the Ambra1 gene in β-thalassemic mice was found to reduce autophagic clearance of α-globin in red blood cell precursors, exacerbating disease phenotypes. Functional characterization of the AMBRA1 gene and these mutations in patient-derived CD34+ cells, edited human umbilical cord blood-derived erythroid progenitor 2 (HUDEP-2) cells, and engineered HUDEP-2 β-thalassemic cells confirmed that AMBRA1 facilitates the autophagic clearance of free α-globin in human erythroid cells. Functional studies demonstrated that AMBRA1 missense mutants destabilize Unc-51-like kinase 1 protein, inhibit light chain 3 protein lipidation, and subsequently hinder autophagic flux, leading to increased α-globin deposition. Additionally, these mutations were associated with erythrotoxic effects in vitro, including increased intracellular reactive oxygen species levels, higher apoptosis rates, and impaired erythr...