FACT复合物是一种保守的组蛋白伴侣，在转录和组蛋白沉积中起关键作用。FACT对于多能干细胞和癌细胞至关重要，但对于大多数哺乳动物细胞而言，大致可以舍弃。FACT的缺失或抑制会阻断多能干细胞的诱导，然而，FACT调控细胞命运决策的机制尚不清楚。为了探索FACT功能的机制，我们构建了AID标记的小鼠胚胎细胞系，用于FACT亚单位SPT16的沉默，并结合新生转录和染色质可及性分析。我们还使用CUT&RUN分析了SPT16的占位，并发现SPT16定位于启动子和增强子元素，与OCT4、SOX2和NANOG的结合有着很强的重叠。在SPT16消耗的时间过程中，核小体侵袭了新的位点，包括SPT16、OCT4、SOX2和NANOG结合的启动子、区域以及TSS-远离位点的DNase I敏感位点。同时，Pou5f1（编码OCT4）、Sox2、Nanog以及与这些基因相关的增强子产生的转录本的转录被下调。我们提出，FACT通过一种精确的基于核小体的调控机制维持细胞多能性，以适当表达与多潜能相关的编码和非编码转录本。© 2023. BioMed Central Ltd., part of Springer Nature.

The FACT complex is a conserved histone chaperone with critical roles in transcription and histone deposition. FACT is essential in pluripotent and cancer cells, but otherwise dispensable for most mammalian cell types. FACT deletion or inhibition can block induction of pluripotent stem cells, yet the mechanism through which FACT regulates cell fate decisions remains unclear.To explore the mechanism for FACT function, we generated AID-tagged murine embryonic cell lines for FACT subunit SPT16 and paired depletion with nascent transcription and chromatin accessibility analyses. We also analyzed SPT16 occupancy using CUT&RUN and found that SPT16 localizes to both promoter and enhancer elements, with a strong overlap in binding with OCT4, SOX2, and NANOG. Over a timecourse of SPT16 depletion, nucleosomes invade new loci, including promoters, regions bound by SPT16, OCT4, SOX2, and NANOG, and TSS-distal DNaseI hypersensitive sites. Simultaneously, transcription of Pou5f1 (encoding OCT4), Sox2, Nanog, and enhancer RNAs produced from these genes' associated enhancers are downregulated.We propose that FACT maintains cellular pluripotency through a precise nucleosome-based regulatory mechanism for appropriate expression of both coding and non-coding transcripts associated with pluripotency.© 2023. BioMed Central Ltd., part of Springer Nature.