AMPK-beta1 Activation Induces Fetal Hemoglobin

Previous studies report that metformin triggers fetal hemoglobin (HbF) induction in human erythroid cells through indirect activation of the AMPK/FOXO3 pathway. Here we investigated the underlying mechanism of HbF induction by direct activation of AMPKß1 in erythroid cells to understand their potential as safe medication for sickle cell disease (SCD). Single-cell RNA sequencing of human bone marrow cells determined that AMPKß1 predominates in the erythroid lineage compared to AMPKß2 and expression of AMPKß1 is mostly restricted to this lineage. Novel selective AMPKß1 activators greatly increased expression of HbF, activated markers of the noncanonical Nrf2 pathway (phosphorylated ULK1 and SQSTM1), and ultimately decreased sickling of SCD donor CD34+ cells under hypoxia. Confirmation of the noncanonical Nrf2 pathway in AMPKß1 driven HbF induction was achieved by abolishing increased HbF using a potent and selective inhibitor for SQSTM1/Keap1 complex formation. Preclinical studies in Townes SCD mice treated with PF-06409577, a clinical candidate AMPKß1 activator, confirmed increased HbF induction and non-canonical Nrf2 pathway activation in erythroid cells, associated with decreased reactive oxidative species in bone marrow and decreased chronic inflammation markers. Based on the narrow tissue expression of AMPKß1, our study strongly supports AMPKß1 activators as safe activators of Nrf2 driven HbF induction compared to direct inhibitors of ubiquitous Keap1. Activation of the AMPKß1/Nrf2 noncanonical pathway may be a promising therapeutic approach for SCD patients. Overall design: Comparative gene expression profiling analysis of RNA-seq data for CD34+ cells treated with compound B, oxindole (N=3) or DMSO (N=3). RNA-seq was conducted after 14 days of erythroid differentiation for each condition.