College of Life Sciences, Jilin University, Changchun, China.
Germline Stem Cells and Microenvironment Lab, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China.
Cell Prolif. 2022 Mar;55(3):e13195. doi: 10.1111/cpr.13195. Epub 2022 Feb 4.
Spermatogonial stem cells (SSCs), the germline stem cells (GSCs) committed to spermatogenesis in niche, can transform into pluripotent state in long-term culture without introduction of exogenous factors, typically in p53 deficiency condition. As the guardian for genomic stability, p53 is associated with epigenetic alterations during SSCs transformation. However, the mechanism is still unknown, since complicated roles of p53 baffle our understanding of the regulating process.
The chromatin accessibility and differentially expressed genes (DEGs) were analysed in p53 and p53 SSCs using the Assay for Transposase-Accessible Chromatin with high-throughput Sequencing (ATAC-seq) and RNA-sequencing (RNA-seq), to explore the connection of p53 and cell fate at chromosomal level.
Several transcription factors (TFs), such as CTCF, SMAD3 and SOX2, were predicted as important factors mediating the transformation. Molecular evidence suggested that SMAD3 efficiently promoted pluripotency-associated gene expression both in fresh and long-term cultured SSCs. However, p53 knockout (KO) is insufficient to induce SMAD3 expression in SSCs.
These observations indicate that SMAD3 is a key factor for SSCs transformation, and an unknown event is required to activate SMAD3 as the prerequisite for SSCs reprogramming, which may occur in the long-term culture of SSCs. This study demonstrates the connection of p53 and pluripotency-associated factors, providing new insight for understanding the mechanisms of SSCs reprogramming and germline tumorigenesis.
精原干细胞（SSC）是生殖系干细胞（GSC），在龛位中致力于精子发生，可以在没有引入外源因素的情况下在长期培养中转化为多能状态，通常在 p53 缺陷条件下。作为基因组稳定性的守护者，p53 与 SSC 转化过程中的表观遗传改变有关。然而，由于 p53 的复杂作用使我们难以理解调控过程，因此其机制仍不清楚。
使用转座酶可及染色质高通量测序（ATAC-seq）和 RNA 测序（RNA-seq）分析 p53 和 p53 SSC 中的染色质可及性和差异表达基因（DEG），以探索 p53 和细胞命运在染色体水平上的联系。
预测了几个转录因子（TF），如 CTCF、SMAD3 和 SOX2，作为介导转化的重要因素。分子证据表明，SMAD3 可有效促进新鲜和长期培养的 SSC 中多能相关基因的表达。然而，p53 敲除（KO）不足以诱导 SSC 中 SMAD3 的表达。
这些观察结果表明，SMAD3 是 SSC 转化的关键因素，并且需要未知事件来激活 SMAD3 作为 SSC 重编程的前提，这可能发生在 SSC 的长期培养中。本研究表明了 p53 与多能相关因子的联系，为理解 SSC 重编程和生殖系肿瘤发生的机制提供了新的见解。
