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

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 erythroid differentiation and maturation. This study sheds light on the molecular association between mutations in ATGs and the exacerbation of β-thalassemia, highlighting the potential role of the AMBRA1 gene as a promising diagnostic and therapeutic target for β-hemoglobinopathies.

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Journal
Blood
Published
2024-12-18
DOI
https://doi.org/10.1182/blood.2023022688
Citations
3
Primary Topic
Hemoglobinopathies and Related Disorders
Type
article
Field-Weighted Citation Impact
1.31
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article

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

Haokun hao Zhang, Mingyan Fang, Qianqian Zhang, Haoyang Huang et al.
3 citations
Blood
Hemoglobinopathies and Related Disorders
1.31
article

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

Haokun hao Zhang, Mingyan Fang, Qianqian Zhang, Haoyang Huang, Ling Ling, Yukio Nakamura, Xiangmin Xu, Yuan Zhuang, Xin Jin, Xinhua Zhang, Daru Lu, Xiaoqin Feng, Binbin Huang, Xiaolei Wei, Xianming Chen, Zhanping Lu, Yu-Shan Huang, Yong Long, Yuhua Ye, Yidan Liang, Yueyan Huang, Bin Lin
article en
3 citations

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 erythroid differentiation and maturation. This study sheds light on the molecular association between mutations in ATGs and the exacerbation of β-thalassemia, highlighting the potential role of the AMBRA1 gene as a promising diagnostic and therapeutic target for β-hemoglobinopathies.

BloodVol. 145(10)
BGI Group (China) (CN), University of Tsukuba (JP), Chongqing University (CN), Fudan University (CN), RIKEN BioResource Research Center (JP), Nanfang Hospital (CN), Vision Medicals (China) (CN), Guangzhou Automobile Group (China) (CN), Dongguan People’s Hospital (CN), Fuling Center Hospital of Chongqing (CN), Affiliated Hospital of Youjiang Medical University for Nationalities (CN), The Second Nanning People's Hospital (CN), First People's Hospital of Nanning (CN), 303 Hospital of People's Liberation Army (CN), University of Chinese Academy of Sciences (CN), BGI Research (CN), Southern Medical University (CN), Yangzhou University (CN), South China University of Technology (CN), Guangzhou Medical University (CN)
Openalex Percentile: Top 17%
Hemoglobinopathies and Related Disorders
1.31
DOISourceOpenAlex
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