PT - JOURNAL ARTICLE AU - Jinyue Liao AU - Shuk Han Ng AU - Jiajie Tu AU - Alfred Chun Shui Luk AU - Yan Qian AU - Nelson Leung Sang Tang AU - Bo Feng AU - Wai-Yee Chan AU - Pierre Fouchet AU - Tin-Lap Lee TI - Single-cell RNA-Seq Resolves Cellular Heterogeneity and Transcriptional Dynamics during Spermatogonia Stem Cells Establishment and Differentiation AID - 10.1101/194696 DP - 2017 Jan 01 TA - bioRxiv PG - 194696 4099 - http://biorxiv.org/content/early/2017/12/30/194696.short 4100 - http://biorxiv.org/content/early/2017/12/30/194696.full AB - In mammals, the transition of gonocytes to spermatogonia and subsequent differentiation provide the foundation of spermatogenesis. Disturbance in this process has been suggested to cause infertility and testicular germ cell tumor. However, systematic understanding on the cellular and molecular basis of this process is still limited, mainly impeded by the asynchrony in development and the lack of stage-specific markers. Using single-cell RNA sequencing on Oct4-GFP+/KIT-cells isolated from PND5.5 mice testes, we dissected the cellular heterogeneity of early germ cells and established molecular regulations during the gonocyte-spermatogonial transition and early spermatogonia differentiation. We demonstrated that gonocyte-spermatogonial transition was characterized by gene expression change related to apoptosis, cell cycle progression, and regulation of migration processes. Pseudotime analysis reconstructed developmental dynamics of the spermatogonial populations and unraveled sequential cellular and molecular transitions. We also uncovered an unexpected subpopulation of spermatogonia primed to differentiation within the undifferentiated compartment, which is characterized by the lack of self-renewal genes and enhanced Oct4 expression and RA responsiveness. Lastly, we revealed a novel cellular state during the germ cell KIT transition, in which cells have initiated differentiation but still retains the expression of molecular determinants of self-renewal. Our study thus provides a novel understanding of cellular and molecular changes during spermatogonia establishment and a comprehensive resource for studying early male germ development and related diseases.