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The autophagy-activating kinase ULK1 mediates clearance of free α-globin in β-thalassemia
18 auth. Christophe Lechauve, Julia Keith, Eugene Khandros, S. Fowler, Kalin Mayberry, Abdullah Freiwan, Christopher S. Thom, Paola Delbini, Paola Delbini, E. B. Romero, ... Jingjing Zhang, I. Motta, I. Motta, Heather S. Tillman, M. Cappellini, M. Cappellini, M. Kundu, M. Weiss
Rapamycin alleviates β-thalassemia by stimulating ULK1-dependent clearance of toxic free α-globin. Unclogging red blood cells In β-thalassemia, a genetic disorder caused by mutations in the β-globin subunit of adult hemoglobin, the pathological cons…
Rapamycin alleviates β-thalassemia by stimulating ULK1-dependent clearance of toxic free α-globin. Unclogging red blood cells In β-thalassemia, a genetic disorder caused by mutations in the β-globin subunit of adult hemoglobin, the pathological consequences are caused by two problems. One is a shortage of adult hemoglobin that can function to transport oxygen, while the other is a buildup of excess α-globin subunits, which damages the red blood cells and thus further impairs oxygen transport in the body. Using mouse models of β-thalassemia as well as patient-derived cells, Lechauve et al. determined that autophagy-activating kinase ULK1 plays a key role in the clearance of accumulated α-globin. The authors also showed that the drug rapamycin stimulates ULK1-dependent autophagy and thus facilitates α-globin clearance. In β-thalassemia, accumulated free α-globin forms intracellular precipitates that impair erythroid cell maturation and viability. Protein quality control systems mitigate β-thalassemia pathophysiology by degrading toxic free α-globin, although the associated mechanisms are poorly understood. We show that loss of the autophagy-activating Unc-51–like kinase 1 (Ulk1) gene in β-thalassemic mice reduces autophagic clearance of α-globin in red blood cell precursors and exacerbates disease phenotypes, whereas inactivation of the canonical autophagy-related 5 (Atg5) gene has relatively minor effects. Systemic treatment with the mTORC1 inhibitor rapamycin reduces α-globin precipitates and lessens pathologies in β-thalassemic mice via an ULK1-dependent pathway. Similarly, rapamycin reduces free α-globin accumulation in erythroblasts derived from CD34+ cells of β-thalassemic individuals. Our findings define a drug-regulatable pathway for ameliorating β-thalassemia.
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5 2019