PRMT4 blocks myeloid differentiation by assembling a methyl-RUNX1-dependent repressor complex

Abstract

Defining the role of epigenetic regulators in hematopoiesis has become critically important, as recurrent mutations or aberrant expression of these genes has been identified in both myeloid and lymphoid hematological malignancies. We found that PRMT4, a type I arginine methyltransferase, whose function in normal and malignant hematopoiesis is unknown, is overexpressed in AML patient samples. Overexpression of PRMT4 blocks the myeloid differentiation of human stem/progenitor cells (HSPCs) while its knockdown is sufficient to induce myeloid differentiation of HSPCs. We demonstrated that PRMT4 represses the expression of miR-223 in HSPCs via the methylation of RUNX1, which triggers the assembly of a multi-protein repressor complex that includes DPF2. As part of a feedback loop, PRMT4 expression is repressed post-transcriptionally by miR-223. Depletion of PRMT4 results in differentiation of myeloid leukemia cells in vitro and their decrease proliferation in vivo. Thus, targeting PRMT4 holds potential as a novel therapy for acute myelogenous leukemia.