Cell Reports
Volume 30, Issue 4, 28 January 2020, Pages 1101-1116.e5
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Article
EGFR Signaling Stimulates Autophagy to Regulate Stem Cell Maintenance and Lipid Homeostasis in the Drosophila Testis

https://doi.org/10.1016/j.celrep.2019.12.086Get rights and content
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Highlights

  • Autophagy is required for regulating CySC maintenance and cyst cell function

  • EGFR signaling stimulates autophagy to control early CC maintenance and behavior

  • Autophagy suppression by TOR in CCs is required for somatic/germline differentiation

  • Defective autophagy results in lipid accumulation and loss of early cyst cells

Summary

Although typically upregulated upon cellular stress, autophagy can also be utilized under homeostatic conditions as a quality control mechanism or in response to developmental cues. Here, we report that autophagy is required for the maintenance of somatic cyst stem cells (CySCs) in the Drosophila testis. Disruption of autophagy in CySCs and early cyst cells (CCs) by the depletion of autophagy-related (Atg) genes reduced early CC numbers and affected CC function, resembling decreased epidermal growth factor receptor (EGFR) signaling. Indeed, our data indicate that EGFR acts to stimulate autophagy to preserve early CC function, whereas target of rapamycin (TOR) negatively regulates autophagy in the differentiating CCs. Finally, we show that the EGFR-mediated stimulation of autophagy regulates lipid levels in CySCs and CCs. These results demonstrate a key role for autophagy in regulating somatic stem cell behavior and tissue homeostasis by integrating cues from both the EGFR and TOR signaling pathways to control lipid metabolism.

Keywords

autophagy
EGFR
TOR
Drosophila
lipids
somatic stem cells
testis

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