Drosophila hematopoiesis bears striking resemblance with that of vertebrates, both in the context of distinct phases and the signaling molecules. Even though, there has been no evidence of Hematopoietic stem cells (HSCs) in Drosophila, the larval lymph gland with its Hedgehog dependent progenitors served as an invertebrate model of progenitor biology. Employing lineage-tracing analyses, we have now identified Notch expressing HSCs in the first instar larval lymph gland. Our studies clearly establish the hierarchical relationship between Notch expressing HSCs and the previously described Domeless expressing progenitors. These HSCs require Decapentapelagic (Dpp) signal from the hematopoietic niche for their maintenance in an identical manner to vertebrate aorta-gonadal-mesonephros (AGM) HSCs. Thus, this study not only extends the conservation across these divergent taxa, but also provides a new model that can be exploited to gain better insight into the AGM related Hematopoietic stem cells (HSCs).
- Lolitika Mandal
- Nidhi Sharma Dey
- Parvathy Ramesh
- Mayank Chugh
- Sudip Mandal
- Lolitika Mandal
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Yukiko M Yamashita, University of Michigan, United States
- Received: May 30, 2016
- Accepted: October 25, 2016
- Accepted Manuscript published: October 26, 2016 (version 1)
- Accepted Manuscript updated: October 31, 2016 (version 2)
- Version of Record published: November 23, 2016 (version 3)
- Version of Record updated: November 30, 2016 (version 4)
- Version of Record updated: September 11, 2019 (version 5)
© 2016, Dey 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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Many adult stem cell communities are maintained by population asymmetry, where stochastic behaviors of multiple individual cells collectively result in a balance between stem cell division and differentiation. We investigated how this is achieved for Drosophila Follicle Stem Cells (FSCs) by spatially-restricted niche signals. FSCs produce transit-amplifying Follicle Cells (FCs) from their posterior face and quiescent Escort Cells (ECs) to their anterior. We show that JAK-STAT pathway activity, which declines from posterior to anterior, dictates the pattern of divisions over the FSC domain, promotes more posterior FSC locations and conversion to FCs, while opposing EC production. Wnt pathway activity declines from the anterior, promotes anterior FSC locations and EC production, and opposes FC production. The pathways combine to define a stem cell domain through concerted effects on FSC differentiation to ECs and FCs at either end of opposing signaling gradients, and impose a pattern of proliferation that matches derivative production.