FACT Inhibition Blocks Induction But Not Maintenance of Pluripotency

Abstract

The histone chaperone facilitates chromatin transactions (FACT) is associated with nuclear processes, including DNA transcription, replication, and repair. We previously showed that FACT is transiently recruited to pluripotency-associated target genes by newly bound Oct4. In this study, we tested the effects of FACT depletion by knockout or chemical inhibition on the induction and maintenance of pluripotency. Clustered regularly interspaced short palindromic repeat (CRISPR)-mediated deletion of the FACT subunit Spt16 did not affect the viability or proliferation of fibroblasts but blocked their ability to form induced pluripotent stem cells. Similarly, a small molecule inhibitor of FACT blocked the induction of pluripotency at an early step in reprogramming, without affecting the viability, proliferation, undifferentiated state, or the expression of core pluripotency genes. Notably, trypsinization and passage of pluripotent cells transiently reintroduced a requirement for FACT. Although FACT has been considered to be an essential transcription elongation factor, these results contribute to the emerging view that it instead promotes transitions between stable chromatin states, including during reprogramming to pluripotency.

Histone chaperone FACT represses retrotransposon MERVL and MERVL-derived cryptic promoters

“…It is intriguing to see that FACT sets a barrier to the acquisition of totipotent cell fate by ESCs (Figure 4A ). This is consistent with the notion that the FACT complex represses cell fate reprogramming ( 82 ), although the FACT complex is not essential to pluripotency maintenance (Figure 1G ) ( 33 , 83 ). Here, we show that the FACT impedes 2-cell like fate conversion through suppressing cryptic promoters derived from TEs.…”

Establishment and Maintenance of Chromatin Architecture Are Promoted Independently of Transcription by the Histone Chaperone FACT and H3-K56 Acetylation in Saccharomyces cerevisiae

“…FACT is essential for viability in many organisms, which has been attributed to central roles in both transcription and replication (Formosa 2012). However, emerging evidence indicates that differentiated cells of higher organisms remain viable and transcriptionally active without FACT (Gurova et al 2018), and that its dominant role might involve maintaining the existing chromatin landscape and promoting transitions to new ones during cell fate changes (Shen et al 2018). Our results support the importance of cooperation between FACT and H3-K56 status in establishing and maintaining chromatin architecture, but leave open questions regarding which physiological processes are impacted by this collaboration.…”

FACT and Ubp10 collaborate to modulate H2B deubiquitination and nucleosome dynamics

“…FACT is found in yeast cells at about two-thirds the abundance of nucleosomes and therefore is a global component of chromatin that participates in a broad range of chromatin-dependent processes (Gurova et al, 2018). These roles include restoring chromatin integrity after disruptions like transcription (Martin et al, 2018) but emerging evidence shows that FACT may have a less prominent role in proliferation of differentiated mammalian cells (Gurova et al, 2018; Shen et al, 2018). Collectively, these findings suggest, instead, that the primary role of FACT is to stabilize or maintain existing global chromatin architectures and promote transitions to new patterns during differentiation.…”