TY - JOUR A1 - Neuschäfer-Rube, Frank A1 - Möller, Ulrike A1 - Püschel, Gerhard Paul T1 - Structure of the 5'-flanking region of the rat prostaglandin f(2alpha) receptor N2 - Prostaglandin F(2alpha) (PGF(2alpha)), modulates hepatocyte functions via a heptahelical G(q)-coupled PGF(2alpha)-receptor (FP-R) which in liver is expressed exclusively in hepatocytes. The aim of the present study was to isolate the 5'-flanking region of the rat FP-R gene and to elucidate its basal and IL-6-modulated transcription control function in rat hepatocytes. The 5'-non-translated region of the rat hepatocyte FP-R mRNA differed from the corresponding region in rat fetal astrocyte or corpus luteum. It was encoded by exons 1a and 2 which were separated by a 1. 4 kb intron containing the exons 1b and 1c coding for the 5'-untranslated region of rat fetal astrocyte and corpus luteum FP-R mRNA, respectively. The transcription initiation site in hepatocytes was localized 263 bp upstream of the start ATG by 5'-RACE. A DNA-fragment covering the 5'-flanking region of the rFP-R gene from - 1 of the transcription initiation site to -2590 bp was cloned and sequenced. Its 3'-two thirds had a 65% sequence identity to the mouse FP-R promoter however no homology to the bovine FP-R promoter. In the overlapping sequence most of the putative transcription factor binding sites were conserved between mouse and rat. The rat promoter contained no classical TATA- or CAAT-boxes but putative binding sites for the transcription factors C/EBP, GATA-1, HNF-1, HNF-3beta, SP-1, and USF. Luciferase reporter gene constructs containing portions of the 5'-flanking region were transfected into rat hepatocytes. Luciferase expression ranked -181 >/= -608 < -1418 > -1821 >/= -2590. The strongest transcriptional activity was conferred by the region between -608 and -1418 containing a cluster of potential HNF-1 and HNF-3beta binding sites that might allow the exclusive expression of FP-R mRNA in hepatocytes. The amount of FP-R mRNA and the luciferase expression under control of the -2590 promoter fragment were reduced by IL-6 in hepatocytes. Copyright 2000 Academic Press. Y1 - 2000 ER - TY - JOUR A1 - Fennekohl, Alexandra A1 - Lucas, Maria A1 - Püschel, Gerhard Paul T1 - Induction by interleukin 6 of G(s)-coupled prostaglandin E(2) receptors in rat hepatocytes mediating a prostaglandin e(2)-dependent inhibition of the hepatocyte's acute phase response N2 - Prostanoids, that are released from nonparenchymal liver cells in response to proinflammatory stimuli, are involved in the regulation of hepatic functions during inflammation. They exert their effects on their target cells via heptahelical receptors in the plasma membrane. For the 5 prostanoids prostaglandin E(2) (PGE(2)), prostaglandin F(2alpha), prostaglandin D(2) (PGD(2)), prostacyclin, and thromboxane A(2) there exist 8 receptors that are coupled to different heterotrimeric G proteins. These receptors are expressed differentially in the 4 principal liver cell types, i.e., hepatocytes, Kupffer cells, sinusoidal endothelial cells, and hepatic stellate cells. It was intriguing, that the messenger RNA (mRNA) of none of the G(s)-coupled prostanoid receptors (DP-R, EP2-R, EP4-R, and IP-R) that can attenuate the inflammatory reaction were present in hepatocytes. The current study shows that the expression of the G(s)-coupled prostanoid receptors EP2-R, EP4-R, and DP-R, but not the IP-R, was efficiently and rapidly up-regulated by treatment of hepatocytes in vitro or rats in vivo with the key acute phase cytokine interleukin 6 (IL-6). In IL-6-treated hepatocytes PGE(2) in turn attenuated the IL-6-induced alpha(2)-macroglobulin formation via a cyclic adenosine monophosphate (cAMP)- dependent signal chain. The data indicate that an IL-6-mediated induction of the previously not expressed EP2-R and EP4- R on hepatocytes might establish a prostanoid-mediated feedback inhibition loop for the attenuation of the acute phase response. Y1 - 2000 ER - TY - JOUR A1 - Böer, Ulrike A1 - Neuschäfer-Rube, Frank A1 - Möller, Ulrike A1 - Püschel, Gerhard Paul T1 - Requirement of N-glycosylation of the prostaglandin E2 receptor EP3beta for correct sorting to the plasma membrane but not for correct folding N2 - Eight heptahelical receptors have been characterized for prostaglandin (PG) D(2), PGE(2), PGF(2alpha), prostacyclin and thromboxane A(2). They share a sequence identity of 40%. All of them have potential N-glycosylation sites. The current study analysed the role of the two N-glycosylation sites in the rat EP3beta-subtype PGE(2) receptor for protein folding and sorting. The N-glycosylation consensus sequences were eliminated by site-directed mutagenesis and receptors expressed in HEK-293 cells. Both potential N-glycosylation sites were used. Their joint elimination resulted in the synthesis of a receptor protein with full binding competence, biological activity and no reduction of affinity; however, the half-life of the non-glycosylated receptor was slightly reduced. Ligand binding to intact stably transfected cells and confocal laser microscopic immunocytochemistry showed that the glycosylated receptor was correctly inserted into the plasma membrane to a much larger extent than the non-glycosylated receptor, which tended to accumulate in the perinuclear zone of the endoplasmic reticulum. Inhibition of N-glycosylation with tunicamycin resulted in a similar perinuclear distribution of the wild-type receptor. Therefore, glycosylation of the EP3beta receptor seems not to be necessary for correct folding of the receptor protein but for the efficient transport of the receptor protein to the plasma membrane. This contrasts with a previous finding which described a reduction of the affinity for PGE(2) of the EP3alpha receptor by elimination of the distal glycosylation site when the receptor protein was expressed in insect cells. Y1 - 2000 ER - TY - JOUR A1 - Rawel, Harshadrai Manilal A1 - Kroll, Jürgen A1 - Riese, B. T1 - Reaction of chlorogenic acid with lysozyme : physicochemical characterization and proteolytic digestion of the derivatives Y1 - 2000 ER - TY - JOUR A1 - Kroll, Jürgen A1 - Rawel, Harshadrai Manilal T1 - Reactions of plant phenols with myoglobin : influence of chemical structure of the phenolic compounds Y1 - 2000 ER - TY - THES A1 - Schwiertz, Andreas T1 - Nachweis und Bedeutung ausgewählter Spezies der Gattung Eubacterium für den humanen Gastrointestinaltrakt Y1 - 2000 ER - TY - JOUR A1 - Kroll, Jürgen A1 - Rawel, Harshadrai Manilal A1 - Seidelmann, N. T1 - Physicochemical properties and susceptibility to proteolytic digestionof myoglobin-phenol derivatives Y1 - 2000 ER - TY - JOUR A1 - Rawel, Harshadrai Manilal A1 - Kroll, Jürgen A1 - Rohn, Sascha T1 - Reactions of phenol substances with lysozyme - physicochemical characterisation and proteolytic digestion of the derivatives Y1 - 2000 ER - TY - JOUR A1 - Gürtler, H. A1 - Schweigert, Florian J. T1 - Physiologie der Laktation Y1 - 2000 ER - TY - JOUR A1 - Schweigert, Florian J. T1 - Vitamine Y1 - 2000 ER -