Histone h3

RPMI 1640 medium and fetal bovine serum (FBS) were purchased from Gibco (NY, USA). LPS (purity of 99%, from Escherichia coli O55:B5) was obtained from Sigma (St. Louis, USA, #L2880). Histone H3 was obtained from Roche Life Science (Stockholm, Sweden). H3 neutralizing antibody was obtained from Abcam (Cambridge, MA, USA, #ab1791). NOD-IN-1 (purity of 99%) was obtained from MCE (USA). VSIG4-siRNA was obtained from RiboBio (Guangzhou, China). The antibodies to H3, NLRP3, GSDMD, IL-1β, IL-18 were purchased from Cell Signaling Technology (Boston, USA). GAPDH, NOD2, RIP2 antibodies were obtained from Proteintech (Wuhan, China). VSIG4 antibody was obtained from Bioss (Beijing, China). Caspase-1 antibody was obtained from Santa Cruz Biotechnology (Dallas, Texas, USA). Secondary antibodies applied were the goat anti-rabbit/mouse fluorescent antibody purchased from LI-COR Biosciences, Inc. (Lincoln, USA). RNAiso Plus, PrimeScript™ RT reagent kit and SYBR Premix Ex Taq kit were purchased from TaKaRa (Japan). Histone H3 ELISA Kit was obtained from Bioswamp (Wuhan, China). IL-1β, IL-18 ELISA Kits were purchased from Elabscience (Wuhan, China).

Histone proteins were purchased from the following commercial sources: unfractionated whole histone from calf thymus (Sigma-Aldrich; H9250) and histone H3 from calf thymus (Roche; 11034758001). Proteases qualified for use in mass spectrometry sample preparation are as follows: trypsin (Promega; V5111), chymotrypsin (Promega; V1061), and clostripain (Promega; V1881). Standards used in LC-MS/MS are as follows: L-lysine monohydrochloride (Sigma-Aldrich; L-5626), Nε-monomethyl-L-lysine hydrochloride (Sigma-Aldrich; 04,685), Nε,Nε -dimethyl-L-lysine monohydrochloride (Sigma-Aldrich; 19,773), Nε,Nε,Nε-trimethyl-lysine hydrochloride (Sigma-Aldrich; T1660), L-arginine hydrochloride (Arg, Sigma-Aldrich; A-5131), NG-monomethyl-L-arginine monoacetate salt (Sigma-Aldrich; 475,886), NG,NG-dimethylarginine dihydrochloride (Sigma-Aldrich; D4268), NG,N′G-dimethyl-L-arginine dihydrochloride (Santa Cruz; sc-222070), L-histidine hydrochloride monohydrate (His, Wako; 084–00702), 3-methyl-L-histidine (Sigma-Aldrich; M9005), 1-methyl-L-histidine (Sigma-Aldrich; 67,520), Nω-propyl-L-arginine hydrochloride (Wako; 512–27111).

GST-PAD4 was purified according to the modified protocol published elsewhere [43 (link)] with required changes for purification of the GST-tagged proteins. Porphyromonas gingivalis HisTag-PPAD was purified as described previously by Bielecka et al. [44 (link)]. Dansyl-Gly-Arg and Dansyl-Gly-Cit peptides were custom-synthetized by Thinkpeptides (Oxford, UK). Purified histone H3, isolated from calf thymus, was purchased from Roche Diagnostics (Mannheim, Germany) and dissolved in MilliQ water. Cl-amidine was purchased from Calbiochem (Darmstadt, Germany) and dissolved in DMSO. DMSO was used as vehicle control in each experiment.