TY  - JOUR
A1  - Schleger, C.
A1  - Becker, Rolf
A1  - Oesch, Franz
A1  - Steinberg, Pablo
T1  - The human p53 gene mutated at position 249 per se is not sufficient to immortalize human liver cells
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Rothe, Manfred
A1  - Kruse, Hans-Peter
T1  - Solving flavor problems by sensory methods
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Rehwald, Matthias
A1  - Neuschäfer-Rube, Frank
A1  - DeVries, Christa
A1  - Püschel, Gerhard Paul
T1  - Possible role for ligand binding of histidine 81 in the second transmembrane domain of the rat prostaglandin F2alpha receptor
N2  - For the five principal prostanoids PGD2, PGE2, PGF2alpha, prostacyclin and thromboxane A2 eight receptors have been identified that belong to the family of G-protein-coupled receptors. They display an overall homology of merely 30%. However, single amino acids in the transmembrane domains such as an Arg in the seventh transmembrane domain are highly conserved. This Arg has been identified as part of the ligand binding pocket. It interacts with the carboxyl group of the prostanoid. The aim of the current study was to analyze the potential role in ligand binding of His-81 in the second transmembrane domain of the rat PGF2alpha receptor, which is conserved among all PGF2alpha receptors from different species. Molecular modeling suggested that this residue is located in close proximity to the ligand binding pocket Arg 291 in the 7th transmembrane domain. The His81 (H) was exchanged by site-directed mutagenesis to Gln (Q), Asp (D), Arg (R), Ala (A) and Gly (G). The receptor molecules were N-terminally extended by a Flag epitope for immunological detection. All mutant proteins were expressed at levels between 50% and 80% of the wild type construct. The H81Q and H81D receptor bound PGF2alpha with 2-fold and 25-fold lower affinity, respectively, than the wild type receptor. Membranes of cells expressing the H81R, H81A or H81G mutants did not bind significant amounts of PGF2alpha. Wild type receptor and H81Q showed a shallow pH optimum for PGF2alpha binding around pH 5.5 with almost no reduction of binding at higher pH. In contrast the H81D mutant bound PGF2alpha with a sharp optimum at pH 4.5, a pH at which the Asp side chain is partially undissociated and may serve as a hydrogen bond donor as do His and Gln at higher pH values. The data indicate that the His-81 in the second transmembrane domain of the PGF2alpha receptor in concert with Arg-291 in the seventh transmembrane domain may be involved in ligand binding, most likely not by ionic interaction with the prostaglandin's carboxyl group but rather as a hydrogen bond donor.
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Hengstler, Jan Georg
A1  - VanDerBurg, Bart
A1  - Steinberg, Pablo
A1  - Oesch, Franz
T1  - Interspecies differences in cancer susceptibility and toxicity
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Bluvshtein, Evgenia
A1  - Glass, George
A1  - Volohonsky, Gloria
A1  - Yaakubowitz, Margalit
A1  - Harness, Ella
A1  - Smorodinsky, Nechama
A1  - Seidel, Albrecht
A1  - Frank, Heinz
A1  - Stark, Avishay Abraham
A1  - Steinberg, Pablo
T1  - Inhibition of the hydrolytic and transpeptidatic activities of rat kidney gamma-glutamyltranspeptidase by specific monoclonal antibodies
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Schieferdecker, Henrike L.
A1  - Pestel, Sabine
A1  - Püschel, Gerhard Paul
A1  - Götze, Otto
T1  - Increase by anaphylatoxin C5a of glucose output in perfused rat liver via prostanoids derived from nonparenchymal cells : direct action of prostaglandins and indirect action of thromboxane A(2) on hepatocytes
N2  - In the perfused rat liver the anaphylatoxin C5a enhanced glucose output, reduced flow, and elevated prostanoid overflow. Because hepatocytes (HCs) do not express C5a receptors, the metabolic C5a actions must be indirect, mediated by e.g. prostanoids from Kupffer cells (KCs) and hepatic stellate cells (HSCs), which possess C5a receptors. Surprisingly, the metabolic C5a effects were not only impaired by the prostanoid synthesis inhibitor, indomethacin, but also by the thromboxane A(2) (TXA(2)) receptor antagonist, daltroban, even though HCs do not express TXA(2) receptors. TXA(2) did not induce prostaglandin (PG) or an unknown factor release from KCs or sinusoidal endothelial cells (SECs), which express TXA(2) receptors, because (1) daltroban did neither influence the C5a-induced release of prostanoids from cultured KCs nor the C5a-dependent activation of glycogen phosphorylase in KC/HC cocultures and because (2) the TXA(2) analog, U46619, failed to stimulate prostanoid release from cultured KCs or SECs or to activate glycogen phosphorylase in KC/HC or SEC/HC cocultures. In the perfused liver, Ca(2+)-deprivation inhibited not only flow reduction but also glucose output elicited by C5a to similar extents as daltroban. Similarly, in the absence of extracellular Ca(2+), flow reduction and glucose output induced by U46619 were almost completely prevented, whereas glucose output induced by the directly acting PGF(2alpha) was only slightly lowered. Thus, in the perfused rat liver PGs released after C5a- stimulation from KCs and HSCs directly activated glycogen phosphorylase in HCs, and TXA(2) enhanced glucose output indirectly mainly by causing hypoxia as a result of flow reduction.
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Steinberg, Pablo
A1  - Klingelhöffer, Alexandra
A1  - Schäfer, Angelika
A1  - Wüst, Günter
A1  - Weiße, Günter
A1  - Oesch, Franz
A1  - Eigenbrodt, Erich
T1  - Expression of pyruvate kinase M2 in preneoplastic hepatic foci of N-nitrosomorpholine-treated rats
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Kruse, Hans-Peter
A1  - Klessen, Brigitta
A1  - Blaut, Michael
T1  - Effects of inulin of faecal bifidobateria in human subjects
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Schweigert, Florian J.
A1  - Gottwald, C.
T1  - Effect of parturition on levels of vitamins A and E and of ß-carotene in plasma and milk of mares
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Steinberg, Pablo
A1  - Fischer, Thomas M.
A1  - Kiulies, Sandra
A1  - Biefang, Katja
A1  - Platt, Karl-Ludwig
A1  - Oesch, Franz
A1  - Böttger, Thomas
A1  - Bulitta, Clemens
A1  - Kempf, Peter
A1  - Hengstler, Jan Georg
T1  - Drug metabolizing capacity of cryopreserved human, rat and mouse liver parenchymal cells in suspension
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Schweigert, Florian J.
A1  - Bonitz, K.
A1  - Siegling, Christiane
A1  - Buchholz, Ingeborg
T1  - Distribution of vitamin A, retinol-binding protein (RBP), cellular retinoic acid binding protein (CRABPI) and retinoid X receptor ß (RXRß) in the porcine uterus during early gestation
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Fennekohl, Alexandra
A1  - Schieferdecker, Henrike L.
A1  - Jungermann, Kurt
A1  - Püschel, Gerhard Paul
T1  - Differential expression of prostanoid receptors in hepatocytes, Kupffer cells, sinusoidal endothelial cells and stellate cells of rat liver
N2  - BACKGROUND/AIMS: Prostanoids produced by nonparenchymal cells modulate the function of parenchymal and nonparenchymal liver cells during homeostasis and inflammation via eight classes of prostanoid receptors coupled to different G-proteins. Prostanoid receptor expression in parenchymal and nonparenchymal cells was studied in order to get a better insight into the complex prostanoid-mediated intrahepatic signaling network. METHODS: RNA was isolated from freshly purified parenchymal and nonparenchymal rat liver cells and the mRNA level of all eight prostanoid receptor classes was determined by newly developed semiquantitative reverse transcription-polymerase chain reaction protocols. RESULTS: The mRNAs for the prostanoid receptors were differentially expressed. Hepatocytes were the only cell type which contained the mRNA of the Gq-linked prostaglandin F2alpha receptor; they were devoid of any mRNA for the Gs-linked prostanoid receptors. Kupffer cells possessed the largest amount of mRNA for the Gs-linked prostaglandin E2 receptor subtype 2. Endothelial cells expressed high levels of mRNA for the Gq-linked thromboxane receptor and medium levels of mRNA for the Gs-linked prostacyclin receptor, while stellate cells had the highest levels of mRNA for the prostacyclin receptor. The mRNAs for the Gq-linked prostaglandin E2 receptor subtype 1 and the Gi-linked prostaglandin E2 receptor subtype 3 were expressed in hepatocytes and all nonparenchymal cell types at similar high levels, whereas the mRNA of the Gs-linked prostaglandin D2 receptor was expressed in all nonparenchymal cells at very low levels. CONCLUSIONS: In hepatocytes the prostaglandin F2alpha receptor can mediate an increase in glucose output via an increase of intracellular InsP3 while cAMP-dependent glucose output can be inhibited via the subtype 3 prostaglandin E2 receptor. The subtype 2 prostaglandin E2 receptor can restrain the inflammatory response of Kupffer cells via an increase in intracellular cAMP The thromboxane receptor and the prostacyclin receptor in sinusoidal endothelial and the prostacyclin receptor in stellate cells may be involved in the regulation of sinusoidal blood flow and filtration.
Y1  - 1999
SN  - 0168-8278
ER  - 
TY  - JOUR
A1  - Schweigert, Florian J.
T1  - Anpassung von Atmung und Kreislauf der Meeressäuger an den Lebensraum Wasser
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Mazurek, Sybille
A1  - Eigenbrodt, Erich
A1  - Failing, Klaus
A1  - Steinberg, Pablo
T1  - Alterations in the glycolytic and glutaminolytic pathways after malignant transformation of rat liver oval cells
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Neuschäfer-Rube, Frank
A1  - Oppermann, Martin
A1  - Möller, Ulrike
A1  - Böer, Ulrike
A1  - Püschel, Gerhard Paul
T1  - Agonist-induced phosphorylation by G protein-coupled receptor kinases of the EP4 receptor carboxyl-terminal domain in an EP3/EP4 prostaglandin E(2) receptor hybrid
N2  - Prostaglandin E(2) receptors (EP-Rs) belong to the family of heterotrimeric G protein-coupled ectoreceptors with seven transmembrane domains. They can be subdivided into four subtypes according to their ligand-binding and G protein-coupling specificity: EP1 couple to G(q), EP2 and EP4 to G(s), and EP3 to G(i). The EP4-R, in contrast to the EP3beta-R, shows rapid agonist-induced desensitization. The agonist-induced desensitization depends on the presence of the EP4-R carboxyl-terminal domain, which also confers desensitization in a G(i)-coupled rEP3hEP4 carboxyl-terminal domain receptor hybrid (rEP3hEP4-Ct-R). To elucidate the possible mechanism of this desensitization, in vivo phosphorylation stimulated by activators of second messenger kinases, by prostaglandin E(2), or by the EP3-R agonist M&B28767 was investigated in COS-7 cells expressing FLAG-epitope-tagged rat EP3beta-R (rEP3beta-R), hEP4-R, or rEP3hEP4- Ct-R. Stimulation of protein kinase C with phorbol-12-myristate-13-acetate led to a slight phosphorylation of the FLAG- rEP3beta-R but to a strong phosphorylation of the FLAG-hEP4-R and the FLAG-rEP3hEP4-Ct-R, which was suppressed by the protein kinase A and protein kinase C inhibitor staurosporine. Prostaglandin E(2) stimulated phosphorylation of the FLAG- hEP4-R in its carboxyl-terminal receptor domain. The EP3-R agonist M&B28767 induced a time- and dose-dependent phosphorylation of the FLAG-rEP3hEP4-Ct-R but not of the FLAG-rEP3beta-R. Agonist-induced phosphorylation of the FLAG- hEP4-R and the FLAG-rEP3hEP4-Ct-R were not inhibited by staurosporine, which implies a role of G protein-coupled receptor kinases (GRKs) in agonist-induced receptor phosphorylation. Overexpression of GRKs in FLAG-rEP3hEP4-Ct-R- expressing COS-7 cells augmented the M&B28767-induced receptor phosphorylation and receptor sequestration. These findings indicate that phosphorylation of the carboxyl-terminal hEP4-R domain possibly by GRKs but not by second messenger kinases may be involved in rapid agonist-induced desensitization of the hEP4-R and the rEP3hEP4-Ct-R.
Y1  - 1999
SN  - 1521-0111
ER  - 
TY  - JOUR
A1  - Steinberg, Pablo
A1  - Fischer, Thomas M.
A1  - Arand, Michael
A1  - Park, Eunju
A1  - Elmadfa, Ibrahim
A1  - Rimkus, Gerhard
A1  - Brunn, Hubertus
A1  - Dienes, Hans-Peter
T1  - Acute hepatotoxicity of the polycyclic musk 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthaline (AHTN)
Y1  - 1999
ER  -