A tetramer of BCL11A is required for stable protein production and fetal hemoglobin silencing

Down-regulation of BCL11A protein reverses the fetal (HbF, α 2 γ 2 ) to adult (HbA, α 2 β 2 ) hemoglobin switch and is exploited in gene-based therapy for hemoglobin disorders. Because of reliance on ex vivo cell manipulation and marrow transplant, such therapies cannot lessen disease burden. To develop new small-molecule approaches, we investigated the state of BCL11A protein in erythroid cells. We report that tetramer formation mediated by a single zinc finger (ZnF0) is required for production of steady-state protein. Beyond its role in protein stability, the tetramer state is necessary for γ-globin gene repression, because an engineered monomer fails to engage a critical co-repressor complex. These aspects of BCL11A protein production identify tetramer formation as a vulnerability for HbF silencing and provide opportunities for drug discovery.