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CAF-1 safeguards somatic cell identity during factor-induced reprogramming

ABSTRACT: Cellular differentiation involves profound changes in the chromatic landscape, yet the mechanisms by which somatic cell identity is subsequently maintained remain incompletely understood. To further elucidate regulatory pathways that safeguard the somatic state, we performed two comprehensive RNAi screens targeting chromatin factors during transcription factor-mediated reprogramming of mouse fibroblasts to induced pluripotent stem cells (iPSCs). Remarkably, subunits of the chromatin assembly factor-1 (CAF-1) complex emerged as the most prominent hits from both screens, followed by modulators of lysine sumoylation and heterochromatin maintenance. Suppression of CAF-1 increased reprogramming efficiency by several orders of magnitude and facilitated iPSC formation in as little as 4 days. Mechanistically, CAF-1 suppression led to a more accessible chromatin structure at enhancer elements early during reprogramming. These changes were accompanied by a decrease in somatic heterochromatin domains, increased binding of Sox2 to pluripotency-specific targets and activation of associated genes. Notably, suppression of CAF-1 also enhanced the direct conversion of B cells into macrophages and fibroblasts into neurons. Together, our findings reveal the histone chaperone CAF-1 as a novel regulator of somatic cell identity during transcription factor-induced cell fate transitions and provide a potential strategy to modulate cellular plasticity in a regenerative setting. Gene expression analysis in CAF-1 knockdown and Renilla control during early OKSM-induced reprogramming by microarray

ORGANISM(S): Mus musculus

SUBMITTER: Peter Park

PROVIDER: E-GEOD-72741 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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The histone chaperone CAF-1 safeguards somatic cell identity during transcription factor-induced reprogramming (sequencing)

Project description:During development, specialized cell lineages are generated through the establishment of cell type-specific transcriptional patterns and epigenetic programs. However, the precise mechanisms and regulators that maintain these specialized cell states remain largely elusive. To identify molecules that safeguard somatic cell identity, we performed two comprehensive RNAi screens targeting known and predicted chromatin regulators during transcription factor-mediated reprogramming of mouse fibroblasts to induced pluripotent stem cells (iPSCs). Remarkably, subunits of the chromatin assembly factor-1 (CAF-1) complex emerged as the most prominent hits from both screens, followed by modulators of lysine sumoylation, DNA methylation and heterochromatin maintenance. Suppression of CAF-1 increased reprogramming efficiencies by several orders of magnitude and generated iPSCs two to three times faster compared to controls without affecting cell proliferation. We demonstrate that suppression of CAF-1 leads to a more accessible chromatin structure specifically at enhancer elements early during reprogramming. These changes were accompanied by increased binding of the reprogramming factor Sox2 to ESC-specific regulatory elements and earlier activation of pluripotency-associated genes. Notably, suppression of CAF-1 also enhanced iPSC formation from blood progenitors as well as the direct conversion of B cells into macrophages and fibroblasts into neurons. Together, our findings reveal the histone chaperone CAF-1 as an unanticipated regulator of somatic cell identity and provide a potential strategy to modulate cellular plasticity in a regenerative setting. Keywords: Genome binding/occupancy profiling by high throughput sequencing Chromatin accessibility and Sox2 bindings in CAF-1 knockdown and Renilla control during early OKSM reprogramming by high throughput sequencing

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CAF-1 safeguards somatic cell identity during factor-induced reprogramming

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