Hematopoietic stem/progenitor cells in the adult mammalian bone marrow ensure blood cell renewal. Their cellular microenvironment, called 'niche', regulates hematopoiesis both under homeostatic and immune stress conditions. In the Drosophila hematopoietic organ, the lymph gland, the posterior signalling center (PSC) acts as a niche to regulate the hematopoietic response to immune stress such as wasp parasitism. This response relies on the differentiation of lamellocytes, a cryptic cell type, dedicated to pathogen encapsulation and killing. Here, we establish that Toll/NF-kB pathway activation in the PSC in response to wasp parasitism non-cell autonomously induces the lymph gland immune response. Our data further establish a regulatory network where co-activation of Toll/NF-kB and EGFR signaling by ROS levels in the PSC/niche controls lymph gland hematopoiesis under parasitism. Whether a similar regulatory network operates in mammals to control emergency hematopoiesis is an open question.
- Michèle Crozatier
- Isabelle Louradour
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Bruno Lemaître, Ecole Polytechnique Fédérale de Lausanne, Switzerland
© 2017, Louradour et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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