Cell culture and transfection

The open reading frame (ORF) sequences of green fluorescence protein (GFP) and mouse RSBN1 was subcloned into pCS2-F vector, which contains a C-terminal FLAG tag sequence, and pCAGGS vector by In-fusion HD cloning kit (Takara) according to the manufacturer’s instruction. HeLa cells were maintained in Dulbecco’s modified Eagle Medium (Thermo scientific) supplemented with 10% fetal calf serum (SIGMA), 1% glutamine (Wako), and penicillin-streptomycin (Wako) at 37 ˚C in a humidified 5% CO2 atmosphere in air. The cells were transfected using ScreenFect^TM A plus (Wako) following manufacturer’s instruction. HeLa cells were cultured for 24 hours and re-seeded onto poly-L-lysine coated coverslips, followed by immunostaining analysis. For histone extraction, HeLa cells were electroporated by the pCS2F-GFP-RSBN1 using NEPA21 (Nepa Gene) according to manufacturer’s instruction. All transfections were repeated at least three times.