Single cell transcriptome analysis reveals an essential role for Gata2b in hematopoietic lineage decisions in zebrafish

Gioacchino, Emanuele; Koyunlar, Cansu; Looper, Hans de; Jong, Madelon M.E. de; Dobrzycki, Tomasz; Hoogenboezem, Remco M.; Peulen, Joke; Bosch, Dennis; Strien, Paulette van; Royen, Martin E. van; French, Pim J.; Bindels, Eric M.; Monteiro, Rui; Gussinklo, Kirsten; Touw, Ivo P.; Pater, Emma de

doi:10.1101/753178

“…Analysis of gata2a um 27 mutants shows a role for Gata2a during primitive myelopoiesis while analysis of gata2b u 5008 mutants show that Gata2b is dispensable for primitive myelopoiesis but is required for definitive myelopoiesis. This phenotype can be observed at 4 dpf and is consistent with decreased myeloid cells in the whole kidney marrow of adult Gata2b mutants ( Gioacchino et al, 2019 ). Butko et al (2015) showed using an elegant genetic switch experiment and gata2b derived promoter elements that the majority of adult myeloid cells are derived from gata2b + cells.…”

Section: Discussionsupporting

confidence: 75%

Differential Requirement of Gata2a and Gata2b for Primitive and Definitive Myeloid Development in Zebrafish

Peña

¹

,

Lubin

²

,

Rowell

³

et al. 2021

Front. Cell Dev. Biol.

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Germline loss or mutation of one copy of the transcription factor GATA2 in humans leads to a range of clinical phenotypes affecting hematopoietic, lymphatic and vascular systems. GATA2 heterozygous mice show only a limited repertoire of the features observed in humans. Zebrafish have two copies of the Gata2 gene as a result of an additional round of ancestral whole genome duplication. These genes, Gata2a and Gata2b, show distinct but overlapping expression patterns, and between them, highlight a significantly broader range of the phenotypes observed in GATA2 deficient syndromes, than each one alone. In this manuscript, we use mutants for Gata2a and Gata2b to interrogate the effects on hematopoiesis of these two ohnologs, alone and in combination, during development in order to further define the role of GATA2 in developmental hematopoiesis. We define unique roles for each ohnolog at different stages of developmental myelopoiesis and for the emergence of hematopoietic stem and progenitor cells. These effects are not additive in the haploinsufficient state suggesting a redundancy between these two genes in hematopoietic stem and progenitor cells. Rescue studies additionally support that Gata2b can compensate for the effects of Gata2a loss. Finally we show that adults with loss of combined heterozygosity show defects in the myeloid compartment consistent with GATA2 loss in humans. These results build on existing knowledge from other models of GATA2 deficiency and refine our understanding of the early developmental effects of GATA2. In addition, these studies shed light on the complexity and potential structure-function relationships as well as sub-functionalization of Gata2 genes in the zebrafish model.

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“…gata2b mutants, on the other hand, present a reduction in HSC at the onset of definitive hematopoiesis and have defect in neutrphil and monocytic differentiation lineages as adults 40 . Surprisingly, there were no obvious hematopoietic defects in the adult gata2b -/-; gata2a -/fish, suggesting GATA2 is not required for hematopoiesis 34 .…”

Section: Discussionmentioning

confidence: 99%

Redundant mechanisms driven independently by RUNX1 and GATA2 for hematopoietic development

Bresciani¹,

Carrington

²

,

Yu³

et al. 2021

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RUNX1 is essential for the generation of hematopoietic stem cells (HSCs). Runx1 null mouse embryos lack definitive hematopoiesis and die in mid-gestation. However, even though zebrafish embryos with a runx1 W84X mutation have defects in early definitive hematopoiesis, some runx1W84X/W84X embryos can develop to fertile adults with blood cells of multi-lineages, raising the possibility that HSCs can emerge without RUNX1. Here, using three new zebrafish runx1-/- lines we uncovered the compensatory mechanism for runx1-independent hematopoiesis. We show that, in the absence of a functional runx1, a cd41-GFP+ population of hematopoietic precursors still emerge from the hemogenic endothelium and can colonize the hematopoietic tissues of the mutant embryos. Single-cell RNA sequencing of the cd41-GFP+ cells identified a set of runx1-/--specific signature genes during hematopoiesis. Significantly, gata2b, which normally acts upstream of runx1 for the generation of HSCs, was increased in the cd41-GFP+ cells in runx1- /- embryos. Interestingly, genetic inactivation of both gata2b and its paralog, gata2a, did not affect hematopoiesis. However, knocking out runx1 and any three of the four alleles of gata2a and gata2b abolished definitive hematopoiesis. Gata2 expression was also upregulated in hematopoietic cells in Runx1-/- mice, suggesting the compensatory mechanism is conserved. Our findings indicate that RUNX1 and GATA2 serve redundant roles for HSC production, acting as each other's safeguard.

show abstract

Redundant mechanisms driven independently by RUNX1 and GATA2 for hematopoietic development

Bresciani

¹

,

Carrington

²

,

Yu

³

et al. 2021

Preprint

1

0

View full text Add to dashboard Cite

RUNX1 is essential for the generation of hematopoietic stem cells (HSCs). Runx1 null mouse embryos lack definitive hematopoiesis and die in mid-gestation. However, even though zebrafish embryos with a runx1 W84X mutation have defects in early definitive hematopoiesis, some runx1W84X/W84X embryos can develop to fertile adults with blood cells of multi-lineages, raising the possibility that HSCs can emerge without RUNX1. Here, using three new zebrafish runx1-/- lines we uncovered the compensatory mechanism for runx1-independent hematopoiesis. We show that, in the absence of a functional runx1, a cd41-GFP+ population of hematopoietic precursors still emerge from the hemogenic endothelium and can colonize the hematopoietic tissues of the mutant embryos. Single-cell RNA sequencing of the cd41-GFP+ cells identified a set of runx1-/--specific signature genes during hematopoiesis. Significantly, gata2b, which normally acts upstream of runx1 for the generation of HSCs, was increased in the cd41-GFP+ cells in runx1- /- embryos. Interestingly, genetic inactivation of both gata2b and its paralog, gata2a, did not affect hematopoiesis. However, knocking out runx1 and any three of the four alleles of gata2a and gata2b abolished definitive hematopoiesis. Gata2 expression was also upregulated in hematopoietic cells in Runx1-/- mice, suggesting the compensatory mechanism is conserved. Our findings indicate that RUNX1 and GATA2 serve redundant roles for HSC production, acting as safeguard for each other.

show abstract

Single cell transcriptome analysis reveals an essential role for Gata2b in hematopoietic lineage decisions in zebrafish

Cited by 4 publications

References 75 publications

Differential Requirement of Gata2a and Gata2b for Primitive and Definitive Myeloid Development in Zebrafish

Differential Requirement of Gata2a and Gata2b for Primitive and Definitive Myeloid Development in Zebrafish

Redundant mechanisms driven independently by RUNX1 and GATA2 for hematopoietic development

Redundant mechanisms driven independently by RUNX1 and GATA2 for hematopoietic development

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