5 μg of this construct or pGL3-Basic. Promoter activity was assayed using the Dual-Luciferase Reporter Assay system (Promega). For overexpression
studies, rat BSC cells were transfected for 48 hours with the pCMV6-rMAT2A vector (125 ng) (OriGene, Rockville, MD) or pcDNA 3.1(−) rat C/EBP beta (500 ng) (Plasmid 12558, Addgene, Cambridge, MA). All transient transfections were performed using the Superfect reagent (Qiagen, Valencia, CA).20 RSG-treated BSC cells were transfected with FlexiTube siRNAs (Qiagen) against rat PPARγ, rat C/EBPβ, or a negative Compound Library control siRNA or using RNAiMax (Invitrogen, Carlsbad, CA).15, 20 BSC cells or day 5 primary HSCs were transfected with Silencer Select siRNAs (Invitrogen) against PPARβ at a concentration of 30 nM for 48 hours using RNAiMAX. The adenoviral (Adv) vector containing full-length PPARγ (PPARγ
Adv) or green fluorescent protein (GFP; negative control Adv) was kindly provided by Dr. Hidekazu Tsukamoto. The vector was amplified in 293 cells.6 Viruses were purified on Vivapure AdenoPack-20 purification columns (Sartorius Stedim Biotech, GmBH, Germany). The viral titer was determined by the TCID50 (tissue culture infectious dose).6 Birinapant BSC cells were transduced with Adv at a multiplicity of infection of 100 for a period of 72 hours. Reverse-transcribed RNA was subjected to real-time reverse-transcription polymerase chain reaction MCE (RT-PCR) usingTaqMan probes for rat MAT2A, PPARγ, PPARβ, C/EBPβ, and the housekeeping gene glyceraldehyde 3-phosphate dehydrogenase (ABI, Foster City, CA) using described PCR conditions.15 Total cellular protein was subjected to western blotting using antibodies for MAT2A (Novus Biologicals, Littleton, CO), PPARγ, PPARβ, C/EBPβ (Santa Cruz Biotechology, Santa Cruz, CA), and control, β-actin (Abcam). Blots were quantified using the Quantity One densitometry program (Bio-Rad Laboratories, Hercules, CA).
The rat MAT2A promoter sequence19 was analyzed by the transcription element search system21 and MATInspector,22 and putative PPREs were identified. A matrix similarity score was calculated according to the software instructions. Chromatin immunoprecipitation (ChIP) assays were performed using the ChampionChIP kit (SABiosciences, Frederick, MD). Sonicated chromatin was immunoprecipitated with 4 μg of antibodies against PPARγ, PPARβ, or GFP, was reverse cross-linked, and was PCR-amplified for 35 cycles with primers described in Table 1. ChIP-ready genomic DNA was subjected to real-time PCR using the Maxima SybrGreen mastermix (Thermo Scientific, Rockford, IL) and ChIP primers (Table 1). The thermal profile consisted of initial denaturation at 95°C for 15 minutes, 40 cycles at 95°C for 15 seconds, 58°C for 30 seconds, and 72°C for 30 seconds. The cycle threshold (Ct value) of PPAR-immunoprecipitated genomic DNA was normalized to input DNA to obtain the ΔCt.