Pioneer transcription factor Runx2 affecting biological function of Schwann Cells via self-inducible reconstruction of super-silencer to remodel chromatin [TF CUT&Tag]

The expression of Runx2 in Schwann cells (SCs) increases significantly in the early stage of injury, but its underlying regulating mechanism remained unclear. After up-regulating Runx2 expression in SCs, the proliferation and migration ability of SCs decrease with increased cell apoptosis rate, and no obvious accelaration of axon regeneration rate could be seen when co-cultured with dorsal root ganlia. Through genome-wide mapping of the chromatin landscape, Runx2 displayed features of pioneer transcription factor (pTFs), which could independently action without histone modification, and execute positive feedback up-regulating gene expression of itself. In the meanwhile, it could construct the epigenetic mechanism of silencer to limit interactions of other transcription factors, then finally affect the fate of SCs, expecially SCs' ability to deal with lipoproteins and form myelin. This study provides noval insight into key function of Runx2 in SCs as pTFs relying on its ability to reorganize the chromatin landscape within SCs, and interfering with the metabolism and synthesis of myelin sheaths by forming super silencers, therefore affecting the regeneration process of peripheral nerves. Overall design: SCs from neonatal 3-5 day SD rats were isolated and purified. The purified P0 SCs were randomly divided into the Runx2-OE group and EGFP (empty vector) group. SCs were transfected with Runx2-OE or EGFP adenovirus at a concentration of MOI = 200. After 72 hours of incubation in the incubator, the changes in cell morphology were observed under laser confocal microscope. CUT&TAG assay was performed as described previously with modifications.