Project description:microRNA expression in human monocyte-derived DCs following stimulation with NOD2 ligand MDP, TLR2 ligand Pam3CSK4, or both. 4 condition experiment with two timepoints, and 4 biological replicates. Conditions: unstimulated; MDP stimulated; Pam3CSK4 stimulated; MDP + Pam3CSK4 stimulated. Timepoints: 4 hours and 24 hours.
Project description:Little is known about the early transcriptional events in innate immune signaling in immature and tolerogenic monocyte-derived dendritic cells (DCs), the professional antigen-presenting cells of our immune system. TLR ligands usually induce a proinflammatory transcriptional response, whereas IL10 and/or dexamethasone induce a more tolerogenic phenotype. We used Affymetrix microarrays to obtain detailed information underlying pro- and anti-inflammatory transcriptional responsesand transcriptional networks in DCs A pilot experiment was performed in which monocyte-derived DCs were either treated with TLR4 ligand LPS, or IL10 and dexamethason. Furthermore, IL10/dexamethason treated cells were also stimulated with LPS for an additional 6 hr. All samples were then subjected to global gene expression analysis using Affymetrix technology.
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.