ChIP-Seq of CEBP-Beta in Rattus norvegicus:  regenerating liver
Approximately 50 ug of minced liver was fixed with 1% formaldehyde in culture medium for 10 min at room temperature followed by quenching with 0.125 M glycine for 5 min. The tissue was washed twice with ice-cold PBS and lysed in 1 ml of lysis buffer (1% SDS, 10 mM EDTA, 50 mM Tris pH8.0) for at least 30 min on ice. The crosslinked chromatin was sheared to an average size of 200-400 bp by ten 30-second pulses using a BiorupterTM sonicator (Diagenode). The lysate was then centrifuged to remove cell debris, and the chromatin was quantified in a UV spectrophotometer. The chromatin (400 µg) was diluted 10-fold in dilution buffer (0.01% SDS, 1.1% Triton X-100, 1.2 mM EDTA 16.7 mM Tris pH8.10, 167 mM NaCl) and pre-cleared with 25 µl protein A sepharose beads (pre-absorbed with salmon sperm DNA and BSA) for 2 h at 4C. The chromatin supernatant was then incubated overnight with 5 µg of purified antibody at 4C (CEBP-b and CEBP-a, SantaCruz Biotechnology Cat# sc-61X and sc-150X). After incubation with protein A sepharose beads (50 µl) for 2h at 4C, the immune complexes were collected by centrifugation and washed with the following buffers each for 10 min at 4C; RIPA buffer (150 mM NaCl, 50 mM Tris pH8.0, 0.1% SDS), high-salt buffer (500 mM NaCl, 50 mM Tris pH8.0, 0.1% SDS, 1% NP40) LiCl buffer (250 mM LiCl, 50 mM Tris pH8.0, 0.5% Na deoxycholate, 1% NP40) and 2x TE (20 mM Tris pH8.0, 2 mM EDTA). The protein-DNA complexes were eluted from the beads in 450 µl elution buffer (1% SDS, 100 mM NaHCO3) at 55C for 2 h followed by the addition of proteinaseK to 500 µg/ml and overnight incubaton at 65C. Genomic DNA was isolated from the precipitated material as well as from the sheared chromatin input (1/100 of the material used for ChIP) by phenol extraction and ethanol precipitation.