Developmental Cell
Volume 56, Issue 12, 21 June 2021, Pages 1742-1755.e4
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Article
A transitory signaling center controls timing of primordial germ cell differentiation

https://doi.org/10.1016/j.devcel.2021.05.008Get rights and content
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Highlights

  • Steroid pulses coordinate gonadogenesis and PGC differentiation

  • An early steroid pulse initiates migration of swarm cells, a transitory cell type

  • A late steroid pulse induces Torso-like, an activator of Torso receptor, in swarm cells

  • Torso signaling in PGCs relieves Kr-mediated repression of the differentiation gene, bam

Summary

Organogenesis requires exquisite spatiotemporal coordination of cell morphogenesis, migration, proliferation, and differentiation of multiple cell types. For gonads, this involves complex interactions between somatic and germline tissues. During Drosophila ovary morphogenesis, primordial germ cells (PGCs) either are sequestered in stem cell niches and are maintained in an undifferentiated germline stem cell state or transition directly toward differentiation. Here, we identify a mechanism that links hormonal triggers of somatic tissue morphogenesis with PGC differentiation. An early ecdysone pulse initiates somatic swarm cell (SwC) migration, positioning these cells close to PGCs. A second hormone peak activates Torso-like signal in SwCs, which stimulates the Torso receptor tyrosine kinase (RTK) signaling pathway in PGCs promoting their differentiation by de-repression of the differentiation gene, bag of marbles. Thus, systemic temporal cues generate a transitory signaling center that coordinates ovarian morphogenesis with stem cell self-renewal and differentiation programs, highlighting a more general role for such centers in reproductive and developmental biology.

Keywords

gonad morphogensis
primordial germ cells
stem cells
germline
swarm cell
ecdysone
steroid hormone
transitory signaling center
Torso
Drosophila

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3

Present address: Whitehead Institute for Biomedical Research, Cambridge 02142, USA

4

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