Project description:We are interested in the role of NOTCH1 and Shear Stress in Aortic Valve Endothelium. Primary human aortic valve endothelium was subjected to 4 conditions in vitro. 1) Control siRNA, No shear stress. 2) NOTCH1 siRNA, No shear stress. 3) Control siRNA, 15 dynes/cm2 shear stress. 4) NOTCH1 siRNA, 15 dynes/cm2 shear stress. Triplicates of each condition were pooled for library perp and sequencing
Project description:We are interested in the role of NOTCH1 and Shear Stress in Aortic Valve Endothelium. Overall design: Primary aortic valve endothelial cells were infected with NOTCH1 intracellular domain fused with a myc tag in order to perform ChIP-seq.
Project description:Newborn neurons enter an extended maturation stage, during which they acquire excitability characteristics crucial for development of presynaptic and postsynaptic connectivity. In contrast to earlier specification programs, little is known aboutthe regulatory mechanisms that control neuronal maturation. The Pet-1 ETS (E26 transformation-specific) factor is continuously expressed in serotonin (5-HT) neurons and initially acts in postmitotic precursors to control acquisition of 5-HT transmitter identity. Using a combination of RNA sequencing, electrophysiology, and conditional targeting approaches, we determined gene expression patterns in maturing flow-sorted 5-HT neurons and the temporal requirements for Pet-1 in shaping these patterns for functional maturation of mouse 5-HT neurons. We report a profound disruption of postmitotic expression trajectories in Pet-1 / neurons, which prevented postnatal maturation of 5-HT neuron passive and active intrinsic membrane properties, G-protein signaling, and synaptic responses to glutamatergic, lysophosphatidic, and adrenergic agonists. Unexpectedly, conditional targeting revealed a postnatal stage-specific switch in Pet-1 targets from 5-HT synthesis genes to transmitter receptor genes required for afferent modulation of 5-HT neuron excitability. 5-HT1a autoreceptor expression depended transiently on Pet-1, thus revealing an early postnatal sensitive period for control of 5-HT excitability genes. Chromatin immunoprecipitation followed by sequencing revealed that Pet-1 regulates 5-HT neuron maturation through direct gene activation and repression. Moreover, Pet-1 directly regulates the 5-HT neuron maturation factor Engrailed 1, which suggests Pet-1 orchestrates maturationthrough secondary postmitotic regulatoryfactors. The early postnatal switch in Pet-1targets uncovers a distinct neonatal stage-specific function for Pet-1, during which it promotes maturation of 5-HT neuron excitability. 5-HT neuron mRNA profiles of E11.5, E15.5, and postnatal (P1-P3) wild type (WT) and Pet-1-/- mice were generated by deep sequencing, in triplicate, using Illumina HiSeq 2500. Myc-tagged Pet-1 ChIP-seq was performed on E12.5 to E14.5 hindbrains and sequencing using NextSeq 500.
Project description:Development of an alternative method to ChIP for the identification of DNA bound by transcriptional complexes assayed using next-generation sequencing Next-generation sequencing data from sites identified by different Notch complexes using SpDamID-seq and compared against FAIRE and ChIP data
Project description:The study deals with the elucidation of potential interaction partners of the intracellular domain of the transmembrane receptor Notch1, termed NICD. The NICD is released from the cytoplasmic tail of the Notch receptor by gamma-secretase treatment and translocated as a transcription factor to the nucleus. Here, virally transduced recombinant NICD constructs (wild-type and deltaEP hyperactive mutant) were employed for AP-MS with the aim of identifying novel NICD interactors in a murine T cell leukemia cell line.
Project description:It is widely believed that reorganization of nucleosomes result in availability of transcription factor (TF) binding sites for eukaryotic gene regulation. Recent findings also show TFs induced during physiological perturbations can alter nucleosome occupancy to facilitate DNA binding. Although, these suggest a close relationship between TF binding and nucleosomes, the nature of this interaction, or to what extent it influences transcription is not clear. Moreover, since physiological perturbations induced multiple TFs, relatively direct effect of any TF on nucleosome occupancy remains poorly addressed. With these in mind, we used a single TF to induce physiological changes and following characterization of the two states (before and after induction of the TF) we determined: (a) genome wide binding sites of the TF, (b) promoter nucleosome occupancy and (c) transcriptome profiles, independently in both conditions. We find only ~20% of TF binding results from nucleosome repositioning - interestingly, almost all corresponding genes were transcriptionally altered. Whereas, when TF-occupancy was independent of nucleosome repositioning only a small fraction of corresponding genes were expressed/repressed. These observations suggest a model where TF occupancy leads to transcriptional change only when coupled with nucleosome repositioning in close proximity. This, to our knowledge, for the first time also helps explain why genome wide TF occupancy (e.g., from ChIP-sequencing) typically overlaps with only a small fraction of genes that change expression. The nature of interaction between TF binding and nucleosomes and what extent it influences transcription
Project description:Here, using ChIP-Seq, we examined the targets of Nanog-like and Mxtx2 in blastula stage zebrafish embryos. We found that Nanog-like bind to its known targets like Oct4, Sox2, and Nanog-like. Nanog-like also bound to genes involved in extraembryonic lineage differentiation, like gata3 and krt4 for EVL differentiation, and mxtx2 and slc26a1 for YSL differentiation, mesoderm specification like ntl and tbx3, cell movement like wnt11 and cxcr4b, and signaling genes like ndr1, bmp2b, fgf8a and wnt8a. The binding profile suggests that Nanog-like may play a versatile role involving many developmental processes. We found 11.3% of the genes (1751 out of all annotated 15500 zebrafish genes) and 43.6% of the YSL genes (118 out of 271 genes expressed in the YSL) were bound by Mxtx2, suggesting Mxtx2 bound directly to YSL genes to activate their expression Examination of Nanog-like and Mxtx2 binding sites in 3.5hpf and 4.5hpf zebrafish embryos
Project description:Neuroendocrine (NE) cells use large dense core vesicles (LDCVs) to traffic, process, store and secrete neuropeptide hormones through the regulated secretory pathway. The DIMM basic helix-loop-helix transcription factor of Drosophila controls the level of regulated secretory activity in NE cells. To pursue its mechanisms, we have performed two independent genome-wide analyses of DIMM’s activities: (i) in vivo chromatin immunoprecipitation (ChIP) to define genomic sites of DIMM occupancy and (ii) deep sequencing of purified DIMM neurons to characterize their transcriptional profile. By this combined approach, we showed that DIMM binds to conserved E-boxes in enhancers of 212 genes whose expression is enriched in DIMM-expressing NE cells. DIMM binds preferentially to certain E-boxes within first introns of specific gene isoforms. Statistical machine learning revealed that flanking regions of putative DIMM binding sites contribute to its DNA binding specificity. DIMM’s transcriptional repertoire features at least 20 LDCV constituents. In addition, DIMM notably targets the pro-secretory transcription factor, CREB-A, but significantly, DIMM does not target any neuropeptide genes. DIMM therefore prescribes the scale of secretory activity in NE neurons, by a systematic control of the regulated secretory pathway at steps that are both proximal and distal. DIMM::MYC ChIP-chip (c929>DIMM::MYC/tubGAL80ts) and control (c929>tubGAL80ts): 2 replicates each, input and IP samples. Total of 8 arrays