Project description:We profiled the dynamic interaction of p300 with proximal promoters of human T cells identified a class of genes that rapidly coassemble p300 and RNA polymerase II following mitogen stimulation. We classified the genes that rapidly coassemble p300 and pol II following mitogen stimulation Comparison the unstimulated to P/I stimulated pol II and p300 enrichment fold in Jurkat
Project description:The rate of RNA polymerase II (pol II) elongation can influence splice site selection in nascent transcripts, yet the extent and physiological relevance of this kinetic coupling between transcription and alternative splicing is not well understood. We performed experiments to perturb pol II elongation and then globally compared alternative splicing patterns with genome-wide pol II occupancy. RNA binding and RNA processing functions were significantly enriched among the genes with pol II elongation inhibition-dependent changes in alternative splicing. Under conditions that interfere with pol II elongation, including cell stress, increased pol II occupancy was detected in the intronic regions flanking the alternative exons in these genes, and these exons generally became more included. A disproportionately high fraction of these exons introduced premature termination codons that elicited nonsense-mediated mRNA decay (NMD), thereby further reducing transcript levels. Our results provide evidence that kinetic coupling between transcription, alternative splicing and NMD affords a rapid mechanism by which cells can respond to changes in growth conditions, including cell stress, to coordinate the levels of RNA processing factors with mRNA levels. To monitor pol II distributions, chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq) was performed using an anti-pol II antibody (4H8) and cross-linked chromatin preparations from Jurkat cells, treated with or without pol II elongation inhibitor 5,6-dichloro-1-β-D-ribofuranosyl-benzimidazole (DRB) at 10 and 25 ug/ml respectively prior to phorbol 12-myristate 13-acetate (PMA) stimulation, for 5000+ alternative splicing events.
Project description:Maternal-deposited factors initiate zygotic genome activation (ZGA), driving the maternal-to-zygotic transition; however, the coordination between maternal coactivators and transcription factors (TFs) in this process remains unclear. In this study, by profiling the dynamic landscape of p300 during mouse ZGA, we reveal its role in promoting RNA polymerase II (Pol II) pre-configuration at ZGA gene regions and sequentially establishing enhancer activity and regulatory networks. Moreover, p300/CBP-catalyzed acetylation drives Pol II elongation and minor ZGA gene expression by inducing pivotal TFs such as Dux. Remarkably, the supplementation of exogenous Dux rescues ZGA failure and developmental defects caused by the loss of p300/CBP acetylation. DUX functions as a pioneer factor, guiding p300 and Pol II to minor ZGA gene regions and activating them in a manner dependent on the non-catalytic functions of p300/CBP. Together, our findings reveal a mutual dependency between p300/CBP and DUX, highlighting their coordinated role in regulating minor ZGA activation.
Project description:We profiled the dynamic interaction of p300 with proximal promoters of human T cells identified a class of genes that rapidly coassemble p300 and RNA polymerase II following mitogen stimulation. We classified the genes that rapidly coassemble p300 and pol II following mitogen stimulation
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with P300/CBP and RB proteins. To understand why, experiments with structure-based e1a mutants were analyzed with RNA- and ChIP-seq. The results indicate that e1a displaces RBs from E2F activation domains and, by promoting P300 acetylation of RB1 K873/K874, locks them into a repressing conformation that interacts with repressive chromatin modifying enzymes. e1a then delivers these repressing p300-e1a-RB1 complexes to cell genes that have unusually high P300 association with the gene body, enriched in genes of the TGFb-, TNF-, and IL1-signaling pathways. The P300-e1a-RB complex condenses chromatin, dependent on HDAC activity, P300 lysine acetylase activity, the P300 bromodomain, and acetylation of RB K873/K874 and e1a K239, contributing to repression of host genes that would otherwise inhibit cell cycling. The data suggest why e1a must bind P300/CBP as well as RBs for oncogenic transformation and why a trimeric P300-e1a-RB1 complex is required. Examination of POL II rearrangements by adenoviral e1a in IMR90