4, 7 Histone modifications including acetylation play an important role in these processes, and histone acetyltransferases (HATs) are known to be important in the control of gene transcription and cell cycle progression.8, 9 The HAT cofactor transformation/transcription domain-associated selleck products protein (TRRAP) has been identified as an essential gene in development10 and a component of several HAT complexes (including GCN5/PCAF and Tip60/NuA4).9 Transcription factors
important for cell cycle entry and progression, including c-Myc and E2F, utilize the TRRAP/HAT complexes to activate transcription of their downstream target genes.11-13 This transcription activation is the result of these complexes catalyzing acetylation of the histone proteins in the nucleosomes spanning the target genes. Studies have indicated that TRRAP may function by recruiting HATs to c-Myc and E2F and possibly to other transcription factors, resulting in an open chromatin configuration and increased transcription.9, 14, 15 However, the mechanism and functional significance of the TRRAP/HAT recruitment during organ
regeneration remain largely unknown. The purpose of our study was to define the biological RXDX-106 ic50 function of TRRAP and histone acetylation in activating transcription and cell cycle reentry in liver cells undergoing regeneration in vivo. To accomplish our purpose, we used an inducible TRRAP conditional knockout mouse (TRRAP-CKO) model combined with toxin-induced hepatic injury. Our results revealed that TRRAP plays an essential role in cell cycle reentry and regeneration of the adult liver following acute liver damage and that the mechanism by which TRRAP participates in liver regeneration involves histone modifications and the recruitment of transcription factors to chromatin. BrdU, 5-bromo-2-deoxyuridine; CCl4, carbon tetrachloride; CDK, cyclin dependent kinase; ChIP, chromatin
immunoprecipitation; Cre, Type I topoisomerase from P1 bacteriophage; ES cells, embryonic stem cells; HAT, histone acetyltransferase; PCNA, proliferating cell nuclear antigen; pIpC, polyinosinic-polycytidylic acid; TRRAP, transformation/transcription 上海皓元医药股份有限公司 domain-associated protein; TRRAP-CO, TRRAP-containing (control) mice; TRRAP-CKO, TRRAP conditional knockout mice. TRRAP-CKO mice were generated by crossing TRRAP+/f mice harboring a TRRAP conditional (floxed; f) allele with both TRRAPf/Δ mice (containing one TRRAP floxed [f] and one deleted [Δ] allele)10 and Cre transgenic mice that express Cre recombinase under the control of Mx promoter16 to obtain TRRAPf/ΔCre+ mice. Genotypes of all mice were assessed by southern blotting and polymerase chain reaction (PCR) analysis of tail DNA, as described.10 TRRAPf/ΔCre+ mice were injected intraperitoneally with 250 μg polyinosinic-polycytidylic acid (pIpC; Sigma) in phosphate-buffered saline (PBS), 3 times at 2-day intervals.