FACT-mediated depletion of macroH2A-nucleosome regulates the cell response of macrophage

The histone variant macroH2A has been shown to generally associate with transcriptionally silent chromatin states. However, how macroH2A regulates the chromatin structure and functions in transcriptional process still remains elusive at the molecular level. In this study, we demonstrate that the incorporation of macroH2A does not affect the stability and the folding dynamics of nucleosome, but greatly impairs the FACT’s maintenance function at the nucleosome level. FACT can greatly impair the stability of macroH2A nucleosome, and quickly deplete the macroH2A nucleosome after the first unfolding process. Furthermore, we identify the key residue S139 of macroH2A, whose mutation can rescue the FACT’s function to maintain nucleosome integrity. Genome-wide analyses show that S139 mutation in macroH2A reshapes the position of macroH2A and regulates the stimulation-induced transcription in macrophage. Our findings provide mechanistic insights of how histone variant macroH2A coregulates with FACT at the nucleosome level and functions in cell response of macrophage in immunity.