Project description:This experiment investigates the functional roles of estrogen receptor alpha and beta in peripheral blood leukocytes by using selective estrogen receptor agonists. The agonists that are used are estradiol (E2), the selective ER-alpha agonist PPT (4,4',4''-(4-Propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol) and the selective ER-beta agonist DPN (2,3-bis(4-hydroxyphenyl)-propionitrile).
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:In addition to their role in the development and function of the reproductive system, estrogens have significant anti-inflammatory properties. Although both estrogen receptors (ERs) can mediate anti-inflammatory actions, ERbeta is a more desirable therapeutic target because ERalpha mediates the proliferative effects of estrogens on the mammary gland and uterus. In fact, selective ERbeta agonists have beneficial effects in preclinical models involving inflammation without causing growth-promoting effects on the uterus or mammary gland. However, their mechanism of action is unclear. The purpose of this study was to use microarray analysis to determine whether ERbeta-selective compounds produce their anti-inflammatory effects by repressing transcription of proinflammatory genes. We identified 49 genes that were activated by TNF-alpha in human osteosarcoma U2OS cells expressing ERbeta. Estradiol treatment significantly reduced the activation by TNF-alpha on 18 genes via ERbeta or ERalpha. Most repressed genes were inflammatory genes, such as TNF-alpha, IL-6, and CSF2. Three ERbeta-selective compounds, ERB-041, WAY-202196, and WAY-214156, repressed the expression of these and other inflammatory genes. ERB-041 was the most ERbeta-selective compound, whereas WAY-202196 and WAY-214156 were the most potent. The ERbeta-selective compounds repressed inflammatory genes by recruiting the coactivator, SRC-2. ERB-041 also repressed cytokine genes in PBMCs, demonstrating that ERbeta-selective estrogens have anti-inflammatory properties in immune cells. Our study suggests that the anti-inflammatory effects of ERB-041 and other ERbeta-selective estrogens in animal models are due to transcriptional repression of proinflammatory genes. These compounds might represent a new class of drugs to treat inflammatory disorders. Keywords: estrogen receptor, gene regulation, TNF
Project description:Progesterone receptor-B enhances estrogen responsiveness of breast cancer cells via scaffolding PELP1- and estrogen receptor-containing transcription complexes