Genome-wide screening identifies ZFP91 as a key regulator of EVI1 in myeloid leukemia.

Ecotropic viral integration site 1 (EVI1) is essential for hematopoietic stem cell maintenance, and its aberrant expression is a significant adverse prognostic indicator in myeloid leukemia. EVI1 overexpression typically occurs due to chromosomal rearrangement involving 3q26. However, aberrant EVI1 expression is still observed in numerous cases without 3q26 abnormalities, leading to similarly poor outcomes, while the mechanism behind EVI1 overexpression in these cases remains largely unknown. Here, we performed genome-wide CRISPR screening using cells with GFP knock-in at the EVI1 locus and identified zinc finger protein 91 (ZFP91) was the leading activator of EVI1. ZFP91 knockout significantly reduced EVI1 expression and cell proliferation. We also showed that ZFP91 binds to the EVI1 promoter, enhancing H3K4me3/H3K27ac and chromatin accessibility. Our data showed that the ZFP91-EVI1 axis plays a critical role for activation of EVI1 in myeloid leukemia. Our screening approach represents a powerful and unbiased method for identifying expression regulators that can be broadly applied across a range of contexts.