TY - JOUR A1 - Böer, Ulrike A1 - Fennekohl, Alexandra A1 - Püschel, Gerhard Paul T1 - Sensitization by interleukin-6 of rat hepatocytes to tumor necrosis factor alpha-induced apoptosis N2 - BACKGROUND/AIMS: Tumor necrosis factor (TNF) elicits hepatocyte apoptosis in toxic liver injury and is also central in hepatocyte proliferation after partial hepatectomy. In both circumstances interleukin (IL)-6 levels are also elevated. In mouse liver IL-6 attenuated Fas receptor-mediated apoptosis indicating its interference with pro-apoptotic signal chains. It was, therefore, the aim to examine the modulation by IL-6 of TNFalpha-induced apoptosis in rat hepatocytes. METHODS: Primary rat hepatocytes were treated with IL-6 prior to induction of apoptosis with TNFalpha/ actinomycin D or anti-Fas antibody M-20. Apoptosis was detected by determination of caspase-3 activation and bisbenzimide staining of condensed nuclei. Expression of TNFalpha receptors was analyzed by semi-quantitative polymerase chain reaction and ligand binding studies with [125I]-TNFalpha. RESULTS: IL-6 treatment doubled TNFalpha/actinomycin D- induced caspase-3 activity and significantly enhanced chromatin condensation. By contrast IL-6 inhibited Fas-induced increase in caspase-3 activity by 45% and significantly reduced chromatin condensation. IL-6 increased the mRNA level of TNF-R1 1.35-fold and augmented cell surface binding of [125I]-TNFalpha 3-fold. The latter and TNFalpha-mediated caspase activation was attenuated by prostaglandin E(2). CONCLUSIONS: IL-6 - in contrast to its anti-apoptotic modulation of the Fas-induced pathway - exerted a pro-apoptotic effect on the TNFalpha/actinomycin D-induced apoptosis by increasing the number of TNF-R on hepatocytes. Y1 - 2003 UR - http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12763364 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 - Camargo, Rodolfo Gonzalez A1 - dos Reis Riccardi, Daniela Mendes A1 - Teixeira Ribeiro, Henrique Quintas A1 - Carnevali Junior, Luiz Carlos A1 - de Matos-Neto, Emidio Marques A1 - Enjiu, Lucas A1 - Neves, Rodrigo Xavier A1 - Carola Correia Lima, Joanna Darck A1 - Figueredo, Raquel Galvao A1 - Martins de Alcantara, Paulo Sergio A1 - Maximiano, Linda A1 - Otoch, Jose A1 - Batista Jr., Miguel Luiz A1 - Püschel, Gerhard Paul A1 - Seelaender, Marilia T1 - NF-kappa Bp65 and Expression of Its Pro-Inflammatory Target Genes Are Upregulated in the Subcutaneous Adipose Tissue of Cachectic Cancer Patients JF - Nutrients N2 - Cancer cachexia, of which the most notable symptom is severe and rapid weight loss, is present in the majority of patients with advanced cancer. Inflammatory mediators play an important role in the development of cachexia, envisaged as a chronic inflammatory syndrome. The white adipose tissue (WAT) is one of the first compartments affected in cancer cachexia and suffers a high rate of lipolysis. It secretes several cytokines capable of directly regulating intermediate metabolism. A common pathway in the regulation of the expression of pro-inflammatory cytokines in WAT is the activation of the nuclear transcription factor kappa-B (NF-B). We have examined the gene expression of the subunits NF-Bp65 and NF-Bp50, as well as NF-Bp65 and NF-Bp50 binding, the gene expression of pro-inflammatory mediators under NF-B control (IL-1, IL-6, INF-, TNF-, MCP-1), and its inhibitory protein, nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IB-). The observational study involved 35 patients (control group, n = 12 and cancer group, n = 23, further divided into cachectic and non-cachectic). NF-Bp65 and its target genes expression (TNF-, IL-1, MCP-1 and IB-) were significantly higher in cachectic cancer patients. Moreover, NF-Bp65 gene expression correlated positively with the expression of its target genes. The results strongly suggest that the NF-B pathway plays a role in the promotion of WAT inflammation during cachexia. KW - cancer cachexia KW - inflammation KW - white adipose tissue KW - NF-B KW - IB Y1 - 2015 U6 - https://doi.org/10.3390/nu7064465 SN - 2072-6643 VL - 7 IS - 6 SP - 4465 EP - 4479 PB - MDPI CY - Basel ER - TY - GEN A1 - Camargo, Rodolfo Gonzalez A1 - Riccardi, Daniela Mendes dos Reis A1 - Ribeiro, Henrique Quintas Teixeira A1 - Carnevali Junior, Luiz Carlos A1 - Matos-Neto, Emidio Marques de A1 - Enjiu, Lucas A1 - Neves, Rodrigo Xavier A1 - Lima, Joanna Darck Carola Correia A1 - Figuerêdo, Raquel Galvão A1 - Alcântara, Paulo Sérgio Martins de A1 - Maximiano, Linda A1 - Otoch, José A1 - Batista Jr., Miguel Luiz A1 - Püschel, Gerhard Paul A1 - Seelaender, Marilia T1 - NF-kappa Bp65 and expression of its pro-inflammatory target genes are upregulated in the subcutaneous adipose tissue of cachectic cancer patients N2 - Cancer cachexia, of which the most notable symptom is severe and rapid weight loss, is present in the majority of patients with advanced cancer. Inflammatory mediators play an important role in the development of cachexia, envisaged as a chronic inflammatory syndrome. The white adipose tissue (WAT) is one of the first compartments affected in cancer cachexia and suffers a high rate of lipolysis. It secretes several cytokines capable of directly regulating intermediate metabolism. A common pathway in the regulation of the expression of pro-inflammatory cytokines in WAT is the activation of the nuclear transcription factor kappa-B (NF-κB). We have examined the gene expression of the subunits NF-κBp65 and NF-κBp50, as well as NF-κBp65 and NF-κBp50 binding, the gene expression of pro-inflammatory mediators under NF-κB control (IL-1β, IL-6, INF-γ, TNF-α, MCP-1), and its inhibitory protein, nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκB-α). The observational study involved 35 patients (control group, n = 12 and cancer group, n = 23, further divided into cachectic and non-cachectic). NF-κBp65 and its target genes expression (TNF-α, IL-1β, MCP-1 and IκB-α) were significantly higher in cachectic cancer patients. Moreover, NF-κBp65 gene expression correlated positively with the expression of its target genes. The results strongly suggest that the NF-κB pathway plays a role in the promotion of WAT inflammation during cachexia. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 349 KW - cancer cachexia KW - inflammation KW - white adipose tissue KW - NF-κB KW - IκB Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400163 ER - TY - JOUR A1 - Fayyaz, Susann A1 - Henkel, Janin A1 - Japtok, Lukasz A1 - Krämer, Stephanie A1 - Damm, Georg A1 - Seehofer, Daniel A1 - Püschel, Gerhard Paul A1 - Kleuser, Burkhard T1 - Involvement of sphingosine 1-phosphate in palmitate-induced insulin resistance of hepatocytes via the S1P(2) receptor subtype JF - Diabetologia : journal of the European Association for the Study of Diabetes (EASD) N2 - Enhanced plasma levels of NEFA have been shown to induce hepatic insulin resistance, which contributes to the development of type 2 diabetes. Indeed, sphingolipids can be formed via a de novo pathway from the saturated fatty acid palmitate and the amino acid serine. Besides ceramides, sphingosine 1-phosphate (S1P) has been identified as a major bioactive lipid mediator. Therefore, our aim was to investigate the generation and function of S1P in hepatic insulin resistance. The incorporation of palmitate into sphingolipids was performed by rapid-resolution liquid chromatography-MS/MS in primary human and rat hepatocytes. The influence of S1P and the involvement of S1P receptors in hepatic insulin resistance was examined in human and rat hepatocytes, as well as in New Zealand obese (NZO) mice. Palmitate induced an impressive formation of extra- and intracellular S1P in rat and human hepatocytes. An elevation of hepatic S1P levels was observed in NZO mice fed a high-fat diet. Once generated, S1P was able, similarly to palmitate, to counteract insulin signalling. The inhibitory effect of S1P was abolished in the presence of the S1P(2) receptor antagonist JTE-013 both in vitro and in vivo. In agreement with this, the immunomodulator FTY720-phosphate, which binds to all S1P receptors except S1P(2), was not able to inhibit insulin signalling. These data indicate that palmitate is metabolised by hepatocytes to S1P, which acts via stimulation of the S1P(2) receptor to impair insulin signalling. In particular, S1P(2) inhibition could be considered as a novel therapeutic target for the treatment of insulin resistance. KW - FTY720 KW - Insulin signalling KW - Palmitate KW - S1P receptors KW - Sphingolipids KW - Sphingosine 1-phosphate Y1 - 2014 U6 - https://doi.org/10.1007/s00125-013-3123-6 SN - 0012-186X SN - 1432-0428 VL - 57 IS - 2 SP - 373 EP - 382 PB - Springer CY - New York 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 - 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 - Fennekohl, Alexandra A1 - Sugimoto, Yukihiko A1 - Segi, Eri A1 - Maruyama, Takayuki A1 - Ichikawa, Atsushi A1 - Püschel, Gerhard Paul T1 - Contribution of the two Gs-coupled PGE(2)-receptors EP2-receptor and EP4-receptor to the inhibition by PGE2 of the LPS-induced TNF alpha-information in Kupffer cells from EP2-or-EP4-receptor-dficient mice : pivotal role for the EP4- receptor in wild type Kupffer cells N2 - Background/Aims: Prostaglandin E(2) (PGE(2)) is known to inhibit the lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNFalpha) formation in Kupffer cells via an increase in cAMP. Four receptor-subtypes have been cloned for PGE(2) so far. Two of them, the EP2-receptor and the EP4-receptor are linked to stimulatory Gs-proteins and could mediate the inhibition by PGE(2) of TNFalpha-formation.Methods: The significance of both receptors for PGE(2)- dependent inhibition of LPS-induced TNFalpha-formation was studied using Kupffer cells of mice in which either one of the two receptors had been eliminated by homologous recombination.Results: The mRNAs of both receptors were expressed in wild type mouse Kupffer cells. Exogenous PGE(2) inhibited TNFalpha-formation in Kupffer cells lacking either EP2-receptor or EP4-receptor to a similar extent as in control cells, however, 10-fold higher PGE(2) concentrations were needed for half maximal inhibition in cells lacking the EP4-receptor than in control or EP2-receptor- deficient cells. The response to endogenous PGE(2) was blunted in EP4-receptor-deficient mice only and especially after prolonged incubation. Conclusions: The data indicate, that PGE(2) can inhibit TNFalpha-formation via both the EP2- and the EP4-receptor and that, however, the EP4-receptor appears to be physiologically more relevant in Kupffer cells since it conferred a high affinity response to PGE(2). Y1 - 2002 ER - TY - GEN A1 - Gardemann, Andreas A1 - Püschel, Gerhard Paul A1 - Jungermann, Kurt T1 - Nervous control of liver metabolism and hemodynamics N2 - Content: Anatomy of hepatic innervation In vivo studies on the role of hepatic nerves Effects of hepatic nerves in isolated perfused liver Mechanism of action of sympathetic hepatic nerves T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 164 Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-51346 ER - TY - JOUR A1 - Gehre, Christian A1 - Flechner, Marie A1 - Kammerer, Sarah A1 - Küpper, Jan-Heiner A1 - Coleman, Charles Dominic A1 - Püschel, Gerhard Paul A1 - Uhlig, Katja A1 - Duschl, Claus T1 - Real time monitoring of oxygen uptake of hepatocytes in a microreactor using optical microsensors JF - Scientific reports N2 - Most in vitro test systems for the assessment of toxicity are based on endpoint measurements and cannot contribute much to the establishment of mechanistic models, which are crucially important for further progress in this field. Hence, in recent years, much effort has been put into the development of methods that generate kinetic data. Real time measurements of the metabolic activity of cells based on the use of oxygen sensitive microsensor beads have been shown to provide access to the mode of action of compounds in hepatocytes. However, for fully exploiting this approach a detailed knowledge of the microenvironment of the cells is required. In this work, we investigate the cellular behaviour of three types of hepatocytes, HepG2 cells, HepG2-3A4 cells and primary mouse hepatocytes, towards their exposure to acetaminophen when the availability of oxygen for the cell is systematically varied. We show that the relative emergence of two modes of action, one NAPQI dependent and the other one transient and NAPQI independent, scale with expression level of CYP3A4. The transient cellular response associated to mitochondrial respiration is used to characterise the influence of the initial oxygen concentration in the wells before exposure to acetaminophen on the cell behaviour. A simple model is presented to describe the behaviour of the cells in this scenario. It demonstrates the level of control over the role of oxygen supply in these experiments. This is crucial for establishing this approach into a reliable and powerful method for the assessment of toxicity. Y1 - 2020 U6 - https://doi.org/10.1038/s41598-020-70785-6 SN - 2045-2322 VL - 10 IS - 1 PB - Macmillan Publishers Limited, part of Springer Nature CY - [London] ER -