Project description:To determine if there is a physical interaction between the FOXF1 promoter and putative enhancer sequences ~250kb upstream of the promoter chromosome conformation capture-on-chip (4C) analysis was performed. An unanticipated and tremendous amount of the non-coding sequences of the human genome are transcribed. Long non-coding RNAs (lncRNAs) are non-protein coding transcripts longer than 200 nucleotides and their functions remain enigmatic. We demonstrate that deletions of lncRNA genes cause a lethal lung developmental disorder, Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins (ACD/MPV), with parent of origin effects. We identify non-coding overlapping deletions 250 kb upstream to FOXF1 in nine patients with ACD/MPV that arose de novo specifically on the maternally inherited chromosome and delete a fetal lung-specific EST, part of an lncRNA. These deletions define distant cis-regulatory region that harbors a differentially methylated CpG island, binds GLI2 depending on the methylation status of this CpG island, and physically interacts with and up-regulates the FOXF1 promoter, consistent with the absence of the fetal lung-transcribed lncRNA perturbing FOXF1 regulation. LncRNA-mediated chromatin interactions may be responsible for position effect phenomenon and potentially cause many disorders of human development. 4C analysis using 16q24.1 specific 3x720K arrays demonstrated physical interaction between the FOXF1 promoter and distant putative regulatory sequences, about 250 kb upstream in human pulomonary microvascular endothelial cells; 2 biological replicates performed; this chromatin looping was not detected in lymphoblasts that do not express FOXF1 and hence serve as a negative control.
Project description:To determine if there is a physical interaction between the FOXF1 promoter and putative enhancer sequences ~250kb upstream of the promoter chromosome conformation capture-on-chip (4C) analysis was performed. An unanticipated and tremendous amount of the non-coding sequences of the human genome are transcribed. Long non-coding RNAs (lncRNAs) are non-protein coding transcripts longer than 200 nucleotides and their functions remain enigmatic. We demonstrate that deletions of lncRNA genes cause a lethal lung developmental disorder, Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins (ACD/MPV), with parent of origin effects. We identify non-coding overlapping deletions 250 kb upstream to FOXF1 in nine patients with ACD/MPV that arose de novo specifically on the maternally inherited chromosome and delete a fetal lung-specific EST, part of an lncRNA. These deletions define distant cis-regulatory region that harbors a differentially methylated CpG island, binds GLI2 depending on the methylation status of this CpG island, and physically interacts with and up-regulates the FOXF1 promoter, consistent with the absence of the fetal lung-transcribed lncRNA perturbing FOXF1 regulation. LncRNA-mediated chromatin interactions may be responsible for position effect phenomenon and potentially cause many disorders of human development.
Project description:This study provides a map of enhancer-promoter interactions in the intestinal epithelium. We find that key drivers of intestinal differentiation, HNF4 transcription factors, are required for enhancer-promoter interactions at their direct target genes. Depletion of HNF4 disrupts chromatin looping, nearby enhancer chromatin, and target gene expression.
Project description:Substantial evidence supports the hypothesis that enhancers are critical regulators of cell type determination, orchestrating both positive and negative transcriptional programs; however, the basic mechanisms by which enhancers orchestrate interactions with cognate promoters during activation and repression events remain incompletely understood. Here we report the required actions of the LIM domain binding protein, LDB1/CLIM2/NLI, interacting with the enhancer binding protein, ASCL1, to mediate looping to target gene promoters and target gene regulation in corticotrope cells. LDB1-mediated enhancer:promoter looping appears to be required for both activation and repression of these target target gene promoter genes. While LDB1-dependend activated genes are regulated at the level of transcriptional initiation, the LDB1-dependent repressed transcription units appear to be regulated primarily at the level of promoter pausing, with LDB1 regulating recruitment of MTA2, a component of the NuRD complex, on these negative enhancers, required for the repressive enhancer function. These results indicate that LDB1-dependent looping events can deliver repressive cargo to cognate promoters to mediate promoter pausing events in a pituitary cell type. ChIP assay followed by high throughput sequencing (ChIP-seq)
Project description:The most prominent model for long-range enhancer regulation involves direct enhancer-promoter interaction by looping out the intervening chromatin. Using a synthetic biology approach, we have determined that a chromatin unfolding bteween Shh and its enhancers is regulated specifically by the Shh-Brain-Enhancers and is mediated by the recruitment of Poly (ADP-Ribose) Polymerase 1. This ‘chromatin unfolding’ model represents a new mechanism of long-range enhancer-promoter communication in addition to the looping and tracking models. ChIP-on-chip for H3K27me3 on the Shh regulatory region on ESCs and transfected ESCs and NPC showed no loss of Polycomb marks upon Shh activation.
Project description:The most prominent model for long-range enhancer regulation involves direct enhancer-promoter interaction by looping out the intervening chromatin. Using a synthetic biology approach, we have determined that a chromatin unfolding bteween Shh and its enhancers is regulated specifically by the Shh-Brain-Enhancers and is mediated by the recruitment of Poly (ADP-Ribose) Polymerase 1. This ‘chromatin unfolding’ model represents a new mechanism of long-range enhancer-promoter communication in addition to the looping and tracking models. Using 5C study the enhancer-driven activation of the Sonic hedgehog gene (Shh)
Project description:The most prominent model for long-range enhancer regulation involves direct enhancer-promoter interaction by looping out the intervening chromatin. Using a synthetic biology approach, we have determined that a chromatin unfolding between Shh and its enhancers is regulated specifically by the Shh-Brain-Enhancers and is mediated by the recruitment of Poly (ADP-Ribose) Polymerase 1. This ‘chromatin unfolding’ model represents a new mechanism of long-range enhancer-promoter communication in addition to the looping and tracking models. ChIP-on-chip for H3K27me3 and H3K27ac on the Shh regulatory region on ESCs and transfected ESCs showed a gain of H3k27ac specifically on active enhancers and no loss of Polycomb marks upon Shh activation.
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.