Hematopoietic Regulation via GATA Switches

University Of Wisconsin-Madison, Madison WI

Investigators

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Abstract

ABSTRACT Our program to forge principles for how GATA factors act through chromatin to control development, function and dysfunction of the hematopoietic system discovered conserved Gata2 enhancers (+9.5 and -77) that ensure normal hematopoiesis. There were no reports of enhancers essential for stem cell generation or progenitor fate decisions, and few examples of those vital for life. Human +9.5 variants resemble pathogenic GATA2 coding variants in causing GATA2-deficiency syndrome involving immunodeficiency, myelodysplastic syndrome (MDS), and acute myeloid leukemia (AML). -77 disruption also causes MDS/AML. Clinical centers analyze +9.5 and -77 genetic variation. Outcomes from prior research included: (i) innovated a mouse model mimicking epigenetic silencing in GATA2 deficiency syndrome. We demonstrated that GATA2 +9.5 variation is conditionally pathogenic, requiring secondary alterations for pathogenesis; (ii) GATA2 deficiency reduces bone marrow hematopoietic stem/progenitor cell (HSPC) responsiveness to extracellular signals and clinical stem cell expansion regimens; (iii) GATA2-deficient progenitors upregulate innate immune machinery, disrupting cell fate, and GATA2 replacement normalizes the ectopic response; (iv) We demonstrated that GATA2 coding variants can be neomorphic, representing a paradigm-shift; (v) innovated rescue systems with multiomics to quantify GATA2 activity and dissect a novel GATA2 deficiency syndrome variant, which yielded principles for GATA factor function through chromatin; (vi) advised physicians nationally/internationally to interpret GATA2 variation. Pathogenic variants, innovative systems, and multiomics will enable testing of how GATA2-regulated networks govern HSPCs and suppress the onset of blood diseases in which therapies are critically needed. 1. Test models to explain how hematopoietic progenitor genome function is established and maintained. GATA2 activates a Cebpe enhancer to induce C/EBPε expression, promote granulopoiesis, and suppress monocytic differentiation. We will test the hypothesis that GATA2 and C/EBPε operate collectively and independently to establish progenitor genome activity that drives granulopoiesis. 2. Elucidate how a pathogenic GATA2 germline genetic variant retains activity at a subset of GATA2-regulated loci. Our analysis of the ramifications of the GATA2 pathogenic germline variant T354M revealed it retains a subset of its activities. We will test the hypothesis that N-finger activity to counteract the impaired DNA binding of the corrupted C-finger underlies the disproportionate importance of the N-finger for T354M. 3. Generate a human GATA2 genetic curation system to unveil mechanisms and advance clinical genetics. Our assays discriminate activities of human GATA2 variants from wild type GATA2. Although novel GATA2 variants continue to emerge clinically, discriminating between pathogenic, conditionally pathogenic, and benign variants is often inconclusive. We will test the hypothesis that activity metrics will generate a signature for a variant to advance clinical genetic curation, and signatures will also unveil mechanisms.