Circ_0001428 regulates erythropoiesis and γ-globin expression via activating the ATF4-BCL11A axis in β-thalassemia.

β-Thalassemia is a chronic hemolytic anemia caused by mutations in the β-globin gene. Increasing studies have shown that circular RNA (circRNA) plays a key role in abnormal hematopoiesis. Circ_0001428 is formed by circularization of the beta-mannosidase gene. However, little is known about the biological function of circ_0001428 in β-thalassemia. Circ_0001428 was selected from two circRNA microarrays (GSE241141 and GSE196682) of β-thalassemia, and expression levels of circ_0001428, miR-32-3p, miR-325-3p, γ-globin, activating transcription factor 4 (ATF4) and B-cell lymphoma/leukemia 11 A (BCL11A) were validated in 30 patients with β-thalassemia and 30 healthy controls. Cell proliferation, apoptosis, cell cycle, and erythroid differentiation were evaluated using stable knockdown or overexpression of circ_0001428. Fluorescence in situ hybridization, dual-luciferase reporter, and Western blots were performed to confirm interactions between circ_0001428, miR-32-3p/miR-325-3p, and ATF4. Circ_0001428 was downregulated in β-thalassemia patients compared to controls, promoted cell proliferation, decreased cell apoptosis, and inhibited terminal erythroid differentiation and γ-globin production. Mechanistically, circ_0001428 functions as a sponge for miR-32-3p and miR-325-3p to promote ATF4 expression, thereby activating BCL11A expression. Additionally, rescue experiments confirmed that circ_0001428 regulated erythropoiesis and γ-globin expression via promoting the ATF4-BCL11A axis by binding with miR-32-3p/miR-325-3p. Our findings reveal, for the first time, the important role of circ_0001428 in regulating erythropoiesis and γ-globin expression in β-thalassemia. The circ_0001428/miR-32-3p and miR-325-3p/ATF4/BCL11A/γ-globin signaling pathway may be a potential therapeutic target in β-thalassemia, especially for fetal hemoglobin modulation.