Identification of EOMES-expressing spermatogonial stem cells and their regulation by PLZF.

Abstract

Long-term maintenance of spermatogenesis in mammals is supported by GDNF, an essential growth factor required for spermatogonial stem cell (SSC) self-renewal. Exploiting a transgenic GDNF overexpression model, which expands and normalizes the pool of undifferentiated spermatogonia between <i>Plzf ^+/+</i> and <i>Plzf ^lu/lu</i> mice, we used RNAseq to identify a rare subpopulation of cells that express EOMES, a T-box transcription factor. Lineage tracing and busulfan challenge show that these are SSCs that contribute to steady state spermatogenesis as well as regeneration following chemical injury. EOMES+ SSCs have a lower proliferation index in wild-type than in <i>Plzf ^lu/lu</i> mice, suggesting that PLZF regulates their proliferative activity and that EOMES+ SSCs are lost through proliferative exhaustion in <i>Plzf ^lu/lu</i> mice. Single cell RNA sequencing of EOMES+ cells from <i>Plzf ^+/+</i> and <i>Plzf ^lu/lu</i> mice support the conclusion that SSCs are hierarchical yet heterogeneous.