State Key Laboratory of Organ Failure Research, Department of Developmental Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China.
Beijing Advanced Innovation Center for Genomics, School of Life Sciences, Peking University, Beijing 100871, China.
Protein Cell. 2023 Jun 28;14(7):477-496. doi: 10.1093/procel/pwac044.
Although somatic cells can be reprogrammed to pluripotent stem cells (PSCs) with pure chemicals, authentic pluripotency of chemically induced pluripotent stem cells (CiPSCs) has never been achieved through tetraploid complementation assay. Spontaneous reprogramming of spermatogonial stem cells (SSCs) was another non-transgenic way to obtain PSCs, but this process lacks mechanistic explanation. Here, we reconstructed the trajectory of mouse SSC reprogramming and developed a five-chemical combination, boosting the reprogramming efficiency by nearly 80- to 100-folds. More importantly, chemical induced germline-derived PSCs (5C-gPSCs), but not gPSCs and chemical induced pluripotent stem cells, had authentic pluripotency, as determined by tetraploid complementation. Mechanistically, SSCs traversed through an inverted pathway of in vivo germ cell development, exhibiting the expression signatures and DNA methylation dynamics from spermatogonia to primordial germ cells and further to epiblasts. Besides, SSC-specific imprinting control regions switched from biallelic methylated states to monoallelic methylated states by imprinting demethylation and then re-methylation on one of the two alleles in 5C-gPSCs, which was apparently distinct with the imprinting reprogramming in vivo as DNA methylation simultaneously occurred on both alleles. Our work sheds light on the unique regulatory network underpinning SSC reprogramming, providing insights to understand generic mechanisms for cell-fate decision and epigenetic-related disorders in regenerative medicine.
虽然体细胞可以用纯化学物质重编程为多能干细胞（PSCs），但化学诱导多能干细胞（CiPSCs）的真正多能性从未通过四倍体互补测定实现过。精原干细胞（SSCs）的自发重编程是另一种获得 PSCs 的非转基因方法，但这一过程缺乏机制解释。在这里，我们重建了小鼠 SSC 重编程的轨迹，并开发了一种五化学组合，将重编程效率提高了近 80-100 倍。更重要的是，化学诱导生殖系来源的 PSCs（5C-gPSCs）而不是 gPSCs 和化学诱导多能干细胞具有真正的多能性，这可以通过四倍体互补来确定。从机制上讲，SSC 经历了体内生殖细胞发育的反转途径，表现出从精原细胞到原始生殖细胞再到胚胎外胚层的表达特征和 DNA 甲基化动态。此外，SSC 特异性印迹控制区通过印迹去甲基化和随后在 5C-gPSCs 中的两个等位基因之一上重新甲基化，从双等位基因甲基化状态转变为单等位基因甲基化状态，这与体内印迹重编程明显不同，因为 DNA 甲基化同时发生在两个等位基因上。我们的工作揭示了 SSC 重编程背后独特的调控网络，为理解再生医学中细胞命运决定和与表观遗传相关的疾病的通用机制提供了线索。
