CommunicationPolycomb Group Gene E(z) Is Required for Spermatogonial Dedifferentiation in Drosophila Adult Testis

- We find that a Polycomb group component E(z) acts in the Drosophila male germline to regulate maintenance but not the establishment of GSCs.
- We show that GSC maintenance defects upon E(z) inactivation in the germline are not due to failure to respond to key signaling pathways, premature differentiation, or increased cell death.
- We investigate the cell-autonomous requirement of E(z) for dedifferentiation during both the normal aging process and a genetically manipulated situation in which the niche is depleted of GSCs. We demonstrate that E(z) is required for dedifferentiation in both scenarios.

Dedifferentiation is an important process to replenish lost stem cells during aging or regeneration after injury to maintain tissue homeostasis. Here, we report that Enhancer of Zeste [E(z)], a component of the Polycomb repression complex 2 (PRC2), is required to maintain a stable pool of germline stem cells (GSCs) within the niche microenvironment. During aging, germ cells with reduced E(z) activity cannot meet that requirement, but the defect arises from neither increased GSC death nor premature differentiation. Instead, we found evidence that the decrease of GSCs upon the inactivation of E(z) in the germline could be attributed to defective dedifferentiation. During recovery from genetically manipulated GSC depletion, E(z) knockdown germ cells also fail to replenish lost GSCs. Taken together, our data suggest that E(z) acts intrinsically in germ cells to activate dedifferentiation and thus replenish lost GSCs during both aging and tissue regeneration.

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