The content describes the heterogeneity in the emergence of hematopoietic precursor cells from the hemogenic endothelium (HE) in the zebrafish embryo. Using live imaging and new transgenic lines, the authors show that two distinct cell types emerge from the HE with radically different morphodynamics.
The first type, termed EHT pol+ cells, maintains apicobasal polarity and an apical/luminal membrane until release, while the second type, EHT pol- cells, emerge through a more dynamic process reminiscent of trans-endothelial migration without clear apicobasal polarity.
The authors provide evidence that the balance between these two emergence types depends on the tuning of apicobasal polarity at the level of the HE, which is sensitive to interference with the transcription factor Runx1. Specifically, expression of a dominant-negative form of Runx1 (dt-Runx1) leads to an accumulation of EHT pol+ cells, suggesting a role for Runx1 in controlling the molecular events that tune apicobasal polarity during the EHT process.
The authors also show that the zebrafish Pard3 isoform, Pard3ba, is sensitive to interference with Runx1 activity. Pard3ba exhibits a heterogeneous spatial distribution along the aortic axis, with its mRNAs preferentially localized in the vicinity of hemogenic/EHT cells in wild-type embryos. This spatial distribution is disrupted in dt-Runx1 mutants, further supporting the idea of a signaling crosstalk between aortic and hemogenic cells that controls cell polarity and its associated features during the EHT process.
Overall, the study highlights critical cellular and dynamic events of the endothelial-to-hematopoietic transition that support emergence complexity, with potential implications for cell fate determination.
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by TORCQ,L., MA... alle www.biorxiv.org 09-03-2023
https://www.biorxiv.org/content/10.1101/2023.09.01.555862v2Domande più approfondite