日本京都大学Mitinori Saitou课题组实现人类生殖系表观遗传重编程的体外重组。2024年5月20日，《自然》杂志在线发表了这一最新研究成果。

研究人员建立了一种稳健的策略，诱导多能干细胞（PSC）衍生的人类原始生殖细胞（PGC）样细胞（hPGCLC）进行表观遗传重编程和分化，使其成为有丝分裂的前精原细胞或卵原细胞，并对其进行广泛扩增（约>10¹⁰倍）。引人注目的是，骨形态发生蛋白（BMP）信号是这些过程的关键驱动因素：BMP驱动的hPGCLC分化涉及丝裂原活化蛋白激酶/细胞外调节激酶（MAPK/ERK）通路以及DNA甲基转移酶（DNMT）新生和维持活性的减弱，这可能促进了复制耦合、被动的DNA去甲基化。

另一方面，在人类生殖细胞中大量存在的活性DNA去甲基化酶Tens-eleven Translocation（TET）1缺乏的hPGCLC会分化成胚外细胞，包括羊膜细胞，带有二价启动子的关键基因会被抑制；这些细胞不能完全激活对精子发生和卵子生成至关重要的基因，其启动子仍处于甲基化状态。该研究阐明了人类表观遗传重编程的框架，在人类生物学领域取得了根本性进展，并通过生成大量有丝分裂前精原细胞和类卵原细胞，为人类体外配子生成（IVG）研究及其在生殖医学领域的潜在应用树立了里程碑。

据悉，表观遗传重编程可重置亲代表观遗传记忆，并将PGC分化为有丝分裂的前精原细胞或卵原细胞，从而确保生殖细胞的性双态发育，实现全能性。体外重构人类表观遗传重编程仍是一项基本挑战。

附：英文原文

Title: In vitro reconstitution of epigenetic reprogramming in the human germ line

Author: Murase, Yusuke, Yokogawa, Ryuta, Yabuta, Yukihiro, Nagano, Masahiro, Katou, Yoshitaka, Mizuyama, Manami, Kitamura, Ayaka, Puangsricharoen, Pimpitcha, Yamashiro, Chika, Hu, Bo, Mizuta, Ken, Ogata, Kosuke, Ishihama, Yasushi, Saitou, Mitinori

Issue&Volume: 2024-05-20

Abstract: Epigenetic reprogramming resets parental epigenetic memories and differentiates primordial germ cells (PGCs) into mitotic pro-spermatogonia or oogonia, ensuring sexually dimorphic germ-cell development for totipotency 1. In vitro reconstitution of epigenetic reprogramming in humans remains a fundamental challenge. Here, we establish a robust strategy for inducing epigenetic reprogramming and differentiation of pluripotent stem cell (PSC)-derived human PGC-like cells (hPGCLCs) into mitotic pro-spermatogonia or oogonia, coupled with their extensive amplification (~>1010-fold). Strikingly, bone morphogenetic protein (BMP) signalling is a key driver of these processes: BMP-driven hPGCLC differentiation involves an attenuation of the mitogen-activated protein kinase/extracellular-regulated kinase (MAPK/ERK) pathway and both de novo and maintenance DNA methyltransferase (DNMT) activities, likely promoting replication-coupled, passive DNA demethylation. On the other hand, hPGCLCs deficient in tens-eleven translocation (TET) 1, an active DNA demethylase abundant in human germ cells 2,3, differentiate into extraembryonic cells, including amnion, with de-repression of key genes bearing bivalent promoters; these cells fail to fully activate genes vital for spermatogenesis and oogenesis, with their promoters remaining methylated. Our study elucidates the framework of epigenetic reprogramming in humans, making a fundamental advance in human biology, and through the generation of abundant mitotic pro-spermatogonia and oogonia-like cells, represents a milestone for human in vitro gametogenesis (IVG) research and its potential translation into reproductive medicine.

DOI: 10.1038/s41586-024-07526-6

Source: https://www.nature.com/articles/s41586-024-07526-6