Pluripotent stem cells (PSCs) are central to development as they are the precursors of all cell types in the embryo. Therefore, maintaining a stable karyotype is essential, both for their physiological role as well as for their use in regenerative medicine. Karyotype abnormalities in PSCs in culture are common but the underlying causes remain unknown. To gain insight, we explore the composition of the centromere and kinetochore in human embryonic and induced PSCs. Centromere function depends on CENP-A nucleosome-defined chromatin. We show that while PSCs maintain abundant pools of CENP-A, CENP-C and CENP-T, these essential centromere components are strongly reduced at stem cell centromeres. Outer kinetochore recruitment is also impaired to a lesser extent, indicating an overall weaker kinetochore while the inner centromere protein Aurora B remains unaffected. We further show that, similar to differentiated human cells, CENP-A chromatin assembly in PSCs requires transition into G1 phase. Finally, reprogramming experiments indicate that reduction of centromeric CENP-A levels is an early event during dedifferentiation, coinciding with global chromatin remodelling. Our characterization of centromeres in human stem cells suggests a possible link between impaired centromere function and stem cell aneuploidies.

多能干细胞 (PSC) 是发育的核心，因为它们是胚胎中所有细胞类型的前体。因此，保持稳定的核型对于它们的生理作用以及在再生医学中的应用都是必不可少的。培养中 PSC 的核型异常很常见，但潜在原因仍然未知。为了深入了解，我们探索了人类胚胎和诱导 PSC 中着丝粒和动粒的组成。着丝粒功能取决于 CENP-A 核小体定义的染色质。我们表明，虽然 PSC 保持着丰富的 CENP-A、CENP-C 和 CENP-T 库，但这些必需的着丝粒成分在干细胞着丝粒处强烈减少。外动粒募集也受到较小程度的损害，表明整体较弱的动粒，而内部着丝粒蛋白 Aurora B 保持不受影响。我们进一步表明，类似于分化的人类细胞，PSC 中的 CENP-A 染色质组装需要过渡到 G1 期。最后，重编程实验表明，着丝粒 CENP-A 水平的降低是去分化过程中的早期事件，与全局染色质重塑相吻合。我们对人类干细胞中着丝粒的表征表明，着丝粒功能受损与干细胞非整倍体之间可能存在联系。与全球染色质重塑相吻合。我们对人类干细胞中着丝粒的表征表明，着丝粒功能受损与干细胞非整倍体之间可能存在联系。与全球染色质重塑相吻合。我们对人类干细胞中着丝粒的表征表明，着丝粒功能受损与干细胞非整倍体之间可能存在联系。