Heterozygous variants in GATA2 contribute to DCML deficiency in mice by disrupting tandem protein binding

Abstract

Accumulating lines of clinical evidence support the emerging hypothesis that loss-of-function mutations of GATA2 cause inherited hematopoietic diseases, including Emberger syndrome; dendritic cell, monocyte B and NK lymphoid (DCML) deficiency; and MonoMAC syndrome. Here, we show that mice heterozygous for an arginine-to-tryptophan substitution mutation in GATA2 (G2R398W/+), which was found in a patient with DCML deficiency, substantially phenocopy human DCML deficiency. Mice heterozygous for the GATA2-null mutation (G2-/+) do not show such phenotypes. The G2R398W protein possesses a decreased DNA-binding affinity but obstructs the function of coexpressed wild-type GATA2 through specific cis-regulatory regions, which contain two GATA motifs in direct-repeat arrangements. In contrast, G2R398W is innocuous in mice containing single GATA motifs. We conclude that the dominant-negative effect of mutant GATA2 on wild-type GATA2 through specific enhancer/silencer of GATA2 target genes perturbs the GATA2 transcriptional network, leading to the development of the DCML-like phenotype. The present mouse model provides an avenue for the understanding of molecular mechanisms underlying the pathogenesis of GATA2-related hematopoietic diseases.

Loss of HSC stemness identity is associated with exhaustion and hyporesponsiveness in GATA2 deficiency syndrome

“…Notably, when compare with the Gata2 +/or Gata2 +9.5 +/mouse models 57 both exhibiting lower expression of Gata2, the Gata2 R396Q/+ and Gata2 R398W/+ murine models with missense mutations demonstrate no reduction in overall Gata2 expression in the LSK compartment 17 . This observation suggests the existence of mechanistic variations depending on the specific type of mutation.…”

“…Notably, at steady-state conditions, the Gata2 R396Q/+ mice unveil an increased proportion of LT-HSCs, which is an unique feature of this model in comparison to the Gata2 +/and Gata2 R398W/+ models, which show a reduction or no significant difference in proportion respectively. Nonetheless, all models display a reduction in ST-HSCs 5,17,61 . Despite an increase in the number of LT-HSCs, our findings provide compelling evidence that the molecular consequences of the mutation lead to impaired functionality of hematopoietic stem and progenitor cells (HSPCs) under challenging conditions.…”

“…However, their impacts remain poorly studied in vivo due to the very small number of available models 17,18 . We therefore developed a knock-in mouse model of Gata2 R396Q mutation and studied its impact on hematopoiesis.…”

GATA 2 Deficiency: Focus on Immune System Impairment

“…Nevertheless, distinctive features of GATA2 deficiency, namely cytopenia involving dendritic cells, monocytes, B or NK lymphocytes, were not found in this mouse line, indicating that quantitative deficits of GATA2 do not represent a suitable model of human disease. Recently, a very promising approach to this problem by following the qualitative rather than quantitative deficit way has been published by Hasegawa and colleagues ( 18 ). They generated mice that expressed the mutant GATA2 protein in which arginine 398 was substituted for tryptophan, resulting in a dominant-negative effect on the native protein in terms of DNA-binding activity that induces perturbations of the regulation of specific target genes.…”