Hartmut Kleinert - Academia.edu (original) (raw)

Papers by Hartmut Kleinert

Journal of Biological Chemistry, Dec 1, 1991

Federal Republic of Germany Octamer sequence elements were analyzed for their capacity to induce ... more Federal Republic of Germany Octamer sequence elements were analyzed for their capacity to induce the 75 K "core" promoter in vivo. The U6 distal sequence element (DSE) which contains a consensus sequence octamer, was able to support efficient 75 K expression in vivo. In contrast, no such function could be attributed to the octamer-like element alone, which is present within the 7 s K DSE. However, conversion of this octamer-like element (ATTTaGCAT) to the octamer consensus sequence ATTTGCAT generated a potent DSE, even in the absence of the CACCC box, which constitutes the major functional element of the 75 K DSE. Both the consensus and the octamer-like sequences revealed no cooperativity with the CACCC box. Together, these results demonstrate that the octamer-like element of the wildtype 7 s K DSE is definitely not functional in vivo. Furthermore, our experiments indicate that in contrast to the RNA polymerase 11-transcribed small nuclear RNA genes, in intact cells a single functional DSE motif is necessary and sufficient for maximal transcription by RNA polymerase I11 of the 7s K RNA gene.

PubMed, Apr 1, 2014

Social isolation and loneliness increase the risk of death as much as well-established risk facto... more Social isolation and loneliness increase the risk of death as much as well-established risk factors for mortality such as cigarette smoking and alcohol consumption. The underlying molecular mechanisms are poorly understood. In the present study, 3 months old male C57BL/6 mice were socially isolated by individual housing for another 3 months. At the age of 6 months, epigenetic changes were analyzed in midbrain. Social isolation of male adult mice led to an increased global DNA methylation, which was associated with enhanced activity of DNA methyltransferase. Di- and trimethylation of global histone H3 lysine 4 (H3K4) were increased in midbrain of socially isolated mice, accompanied by enhanced H3K4 histone methyltransferase activity. In addition, social isolation of adult mice led to activation of histone acetyltransferases as well as of histone deacetylases (HDAC) resulting in a net enhancement of histone H3 lysine 9 (H3K9) acetylation. Gene-specific effects were observed for Hdac1, Hdac3 and the serotonin transporter Slc6a4. Social isolation led to an up-regulation of Hdac1 and Hdac3, associated with decreased DNA methylation in the CpG island of the respective genes. On the contrary, the Slc6a4 gene was down-regulated, which was associated with enhanced DNA methylation. Collectively, the results from the present study demonstrate for the first time that social isolation of adult mice leads to a wide range of global epigenetic changes and these effects may have profound impact on gene expression pattern and phenotype of the socially isolated animals.

Scientific Reports, Oct 21, 2015

Interleukin (IL)-22 is a STAT3-activating cytokine displaying characteristic AU-rich elements (AR... more Interleukin (IL)-22 is a STAT3-activating cytokine displaying characteristic AU-rich elements (ARE) in the 3′-untranslated region (3′-UTR) of its mRNA. This architecture suggests gene regulation by modulation of mRNA stability. Since related cytokines undergo post-transcriptional regulation by ARE-binding tristetraprolin (TTP), the role of this destabilizing protein in IL-22 production was investigated. Herein, we demonstrate that TTP-deficient mice display augmented serum IL-22. Likewise, IL-22 mRNA was enhanced in TTP-deficient splenocytes and isolated primary T cells. A pivotal role for TTP is underscored by an extended IL-22 mRNA half-life detectable in TTP-deficient T cells. Luciferase-reporter assays performed in human Jurkat T cells proved the destabilizing potential of the human IL-22-3′-UTR. Furthermore, overexpression of TTP in HEK293 cells substantially decreased luciferase activity directed by the IL-22-3′-UTR. Transcript destabilization by TTP was nullified upon cellular activation by TPA/A23187, an effect dependent on MEK1/2 activity. Accordingly, IL-22 mRNA half-life as determined in TPA/A23187-stimulated Jurkat T cells decreased under the influence of the MEK1/2 inhibitor U0126. Altogether, data indicate that TTP directly controls IL-22 production, a process counteracted by MEK1/2. The TTP-dependent regulatory pathway described herein likely contributes to the role of IL-22 in inflammation and cancer and may evolve as novel target for pharmacological IL-22 modulation.

ChemInform, Oct 14, 2008

Other bioactive products U 1300 Inhibitors of Inducible NO Synthase Expression: Total Synthesis o... more Other bioactive products U 1300 Inhibitors of Inducible NO Synthase Expression: Total Synthesis of (S)-Curvularin (Ia) and Its Ring Homologues.-The derivatives (II) show improved downregulation of iNOS expression and almost no negative effects on eNOS expression as is desirable for antiinflammatory drugs.

PLOS ONE, Jun 15, 2015

<p>RNA isolated from aortas of ApoE-deficient mice either fed for 18 weeks with normal chow... more <p>RNA isolated from aortas of ApoE-deficient mice either fed for 18 weeks with normal chow diet (ND) or western-type diet (WD) (treated with Galiellalactone (Gal) or vehicle (PBS/EtOH) for 6 weeks) was analyzed for CTSS (<b>A</b>), SPP1 (<b>B</b>), TNFα (<b>C</b>), S100A8 (<b>D</b>), iNOS (<b>E</b>), IL6 (<b>F</b>), and IL17 (<b>G</b>) mRNA expression in qPCR experiments. Data shown are mean + SEM of 4–10 mice (*** = p < 0.001; ** = p < 0.01; * = p < 0.05; ns = not significant vs. WD + PBS/EtOH; one-way ANOVA).</p

Molecular Immunology, Jul 1, 2017

The KH type splicing regulatory protein (KSRP) is a nucleic acid binding protein, which negativel... more The KH type splicing regulatory protein (KSRP) is a nucleic acid binding protein, which negatively regulates the stability and/or translatability of many mRNA species encoding immune-relevant proteins. As KSRP is expressed in immune cells including T and B cells, neutrophils, macrophages and dendritic cells, we wanted to analyze its importance for the development of autoimmune diseases. We chose collagen antibody-induced arthritis (CAIA) as an appropriate autoimmune disease mouse model in which neutrophils and macrophages constitute the main effector cell populations. We compared arthritis induction in wild type (WT) and KSRP −/− mice and paws were taken for histological sections and qPCR analysis. Furthermore, we determined the frequencies of spleen immune cells by flow cytometry. Cytokine levels in spleen cell supernatants were determined by cytometric bead array analyses (CBA). After CAIA induction we unexpectedly observed in WT animals much stronger swelling of the paws than in KSRP −/− mice. In accordance, histological staining of paw sections of KSRP −/− animals revealed much lower frequencies of infiltrating immune cells in the joints compared to WT animals. Furthermore, CAIA-treatment resulted in reduced expression of several inflammatory factors (like CXCL-1, iNOS, TNF-α and S100A8) as well as immune cell marker genes (e.g. LFA-1, CD68, Ly6G) in the joints of KSRP −/− mice. Spleen cells of KSRP −/− mice showed lower frequencies of myeloid cells. On cytokine level IFN-γ production was increased in spleen cells of KSRP −/− mice compared to WT samples. These data surprisingly suggest that the absence of KSRP protects against the induction of inflammatory arthritis.

British Journal of Pharmacology, Oct 1, 2000

The therapeutic use of the antifungal drug amphotericin B (AmB) is limited due to severe side eec... more The therapeutic use of the antifungal drug amphotericin B (AmB) is limited due to severe side eects like glomerular vasoconstriction and risk of renal failure during AmB administration. As nitric oxide (NO) has substantial functions in renal autoregulation, we have determined the eects of AmB on endothelial constitutive NO synthase (ecNOS) expression and activity in human and rat endothelial cell cultures. 2 AmB used at concentrations of 0.6 to 1.25 mg ml 71 led to increases in ecNOS mRNA and protein expression as well as NO production. This was the result of an increased ecNOS mRNA half-life. In contrast, incubation of cells with higher albeit subtoxic concentrations of AmB (2.5 ± 5.0 mg ml 71) resulted in a decrease or respectively in completely abolished ecNOS mRNA and protein expression with a strongly reduced or inhibited ecNOS activity, due to a decrease of ecNOS mRNA half-life. None of the AmB concentrations aected promoter activity as found with a reporter gene construct stably transfected into ECV304 cells. 3 Thus, our experiments show a concentration-dependent biphasic eect of AmB on expression and activity of ecNOS, an eect best explained by AmB in¯uencing ecNOS mRNA stability. In view of the known renal accumulation of this drug the results reported here could help to elucidate its renal toxicity.

International Journal of Hypertension, 2012

Organic nitrates are a group of very effective anti-ischemic drugs. They are used for the treatme... more Organic nitrates are a group of very effective anti-ischemic drugs. They are used for the treatment of patients with stable angina, acute myocardial infarction, and chronic congestive heart failure. A major therapeutic limitation inherent to organic nitrates is the development of tolerance, which occurs during chronic treatment with these agents, and this phenomenon is largely based on induction of oxidative stress with subsequent endothelial dysfunction. We therefore speculated that induction of heme oxygenase-1 (HO-1) could be an efficient strategy to overcome nitrate tolerance and the associated side effects. Indeed, we found that hemin cotreatment prevented the development of nitrate tolerance and vascular oxidative stress in response to chronic nitroglycerin therapy. Vice versa, pentaerithrityl tetranitrate (PETN), a nitrate that was previously reported to be devoid of adverse side effects, displayed tolerance and oxidative stress when the HO-1 pathway was blocked pharmacologically or genetically by using HO-1 +/− mice. Recently, we identified activation of Nrf2 and HuR as a principle mechanism of HO-1 induction by PETN. With the present paper, we present and discuss our recent and previous findings on the role of HO-1 for the prevention of nitroglycerin-induced nitrate tolerance and for the beneficial effects of PETN therapy.

ChemMedChem, Jun 16, 2008

(S)‐Curvularin and its 13‐, 14‐, and 16‐membered lactone homologues were synthesized through a un... more (S)‐Curvularin and its 13‐, 14‐, and 16‐membered lactone homologues were synthesized through a uniform strategy in which a Kochi oxidative decarboxylation and ring‐closing metathesis reactions constitute the key processes. In the evaluation of the anti‐inflammatory effects of the synthesized compounds in assays using cells stably transfected with a human iNOS promoter–luciferase reporter gene construct, the 14‐ and 16‐membered homologues showed a slightly higher inhibitory effect towards iNOS promoter activity than curvularin itself. However, the larger ring homologues also exhibited higher cytotoxicity, manifest in downregulated eNOS promoter activity. In contrast, the di‐O‐acetyl and 4‐chloro derivatives of (S)‐curvularin showed higher inhibitory efficiency towards induction of the iNOS promoter and less negative effect on eNOS promoter activity than curvularin.

Proceedings of the National Academy of Sciences of the United States of America, Nov 9, 1999

Free Radical Biology and Medicine, May 1, 2023

Elsevier eBooks, 2007

Endothelial nitric oxide synthase (eNOS; also referred to as NOS3 or NOSIII), a low output enzyme... more Endothelial nitric oxide synthase (eNOS; also referred to as NOS3 or NOSIII), a low output enzyme is the prototypical isoform being found in endothelial cells. This isoform (like nNOS) synthesizes NO in a short-lasting, pulsatile, Ca++/calmodulin-activated manner. Endothelium-derived NO is a physiologically significant vasodilator and inhibitor of platelet aggregation and adhesion. In addition, vascular NO can prevent leukocyte adhesion to the endothelium by down-regulating the leukocyte adhesion glycoprotein complex CD11/CD18. Finally, endothelial NO has also been shown to inhibit the proliferation of vascular smooth muscle cells. Therefore, endothelial NO is likely to represent a protective anti-atherogenic principle. eNOS expression has also been demonstrated in several nonendothelial cell types such as neurons of the rat hippocampus and other rat brain regions; some epithelial cells; cardiomyocytes, megacaryocytes, and platelets; T cells; and others (for review see …

Nitric Oxide, Jul 1, 2019

Regulation of human inducible nitric oxide synthase expression by an upstream open reading frame,... more Regulation of human inducible nitric oxide synthase expression by an upstream open reading frame, Nitric Oxide (2019), doi:

PubMed, Sep 5, 2005

Human inducible NO synthase (iNOS) expression is regulated by post-transcriptional mechanisms. Th... more Human inducible NO synthase (iNOS) expression is regulated by post-transcriptional mechanisms. The 3'-untranslated region (3'-UTR) of the human iNOS mRNA contains AU-rich elements (ARE), which are known to be important for the regulation of mRNA stability. The 3'-UTR of the human iNOS mRNA has been shown to regulate human iNOS mRNA expression post-transcriptionally. One RNA-binding protein known to interact with AREs and to regulate mRNA stability is the T cell intracellular antigen-1-related protein (TIAR). In RNA binding studies TIAR displayed high affinity binding to the human iNOS 3'-UTR sequence. In RNase protection experiments, the cytokine incubation needed for iNOS expression did not change TIAR expression in DLD-1 cells. However, overexpression of TIAR in human DLD-1 colon carcinoma cells resulted in enhanced cytokine-induced iNOS expression. In conclusion, TIAR seems to be involved in the post-transcriptional regulation of human iNOS expression.

PLOS ONE, Jun 15, 2015

Patients suffering from chronic inflammatory diseases have an increased mortality risk resulting ... more Patients suffering from chronic inflammatory diseases have an increased mortality risk resulting from cardiovascular disorders due to enhanced atherosclerotic and thrombotic events. Until now, it is not completely understood in which way an abnormal expression of pro-inflammatory mediators contributes to this elevated cardiovascular risk, but there is a need for new drugs that on the one hand suppress the expression of pro-inflammatory mediators and on the other hand inhibit arterial platelet adhesion. Thus, we analyzed the anti-inflammatory and anti-thrombotic capacity of the fungal metabolite Galiellalactone in atherosclerosis-prone apolipoprotein E-deficient mice. Treatment of the mice with Galiellalactone lowered the inflammatory expression profile and improved blood clotting times, as well as platelet adhesion to the injured common carotid artery. The results indicate that administration of Galiellalactone is able to reduce the extent of inflammation and arterial platelet adhesion in this mouse model.

Molecular Pharmacology, Oct 1, 2002

We have investigated the impact of the widely used antifungal agent Amphotericin B (AmB) on cytok... more We have investigated the impact of the widely used antifungal agent Amphotericin B (AmB) on cytokine activated aortic endothelial cells (AEC) and their inflammatory response as monitored by cytokine and inducible nitric-oxide synthase (iNOS) expression as well as high-output nitric oxide synthesis. Because both blood-borne infections and systemically administered drugs will first encounter vessel lining endothelial cells, this cell type represents an important participant in innate immune reactions against xenobiotics. Culturing cytokine-activated AEC in the presence of 1.25 g/ml AmB, a concentration equivalent to serum levels during patient treatment, we find increases in iNOS promoter activity up to 120%, in iNOS mRNA or protein expressions by factors of up to 3.5 Ϯ 1.1, and in iNOS activity of up to 180% compared with cells with cytokines This work was supported by grant SFB503 A3 from the Deutsche Forschungsgemeinschaft (to V.K.-B.).

Journal of Biological Chemistry, May 1, 2014

Background: Chronic inflammatory diseases are associated with increased cardiovascular mortality ... more Background: Chronic inflammatory diseases are associated with increased cardiovascular mortality due to accelerated atherosclerosis. Results: Chronic inflammation in tristetraprolin (TTP)-deficient mice leads to endothelial dysfunction, which is related to enhanced Nox2-dependent reactive oxygen species production but independent from TNF-␣. Conclusion: Inflammation-related oxidative stress is an important mediator in inflammation-driven atherogenesis. Significance: In inflammatory diseases oxidative stress seems to be a major cause of cardiovascular events.

American Journal of Pathology, 2012

Echocardiographic analyses of this study were supported by the Federal Ministry of Education and ... more Echocardiographic analyses of this study were supported by the Federal Ministry of Education and Research (BMBF 01EO1003). The authors are responsible for the contents of this publication.

Pathobiology, 1997

We analyzed the influence of heavy-metal ions on human umbilical vein endothelial cells (HUVEC) i... more We analyzed the influence of heavy-metal ions on human umbilical vein endothelial cells (HUVEC) in comparison to proinflammatory cytokines (TNF-alpha, IL-1beta) and lipopolysaccharide (LPS). Adhesion molecule and cytokine expressions are upregulated by heavy-metal exposure. Expression of E-selectin on the cell surface was strongly induced by 1-mM concentrations of NiCl2 and CoCl2, whereas ZnCl2 and CrCl3 had no influence. Furthermore, it is shown that NiCl2 induces mRNA expression of E-selectin, intercellular adhesion molecule-1, IL-6 and IL-8 in a 1-mM concentration. The transcription factor NF-kappaB is known to be involved in the regulation of adhesion molecule expression in endothelial cells after activation by proinflammatory cytokines. We demonstrated that treatment of HUVEC with Ni2+ and Co2+ ions induces the translocation of NF-kappaB p65 and also p50 into the nucleus. NF-kappaB binding activity is enhanced under the influence of heavy metals as determined by mobility shift analysis. P65 and p50 are components of the NF-kappaB complexes as confirmed by supershift analysis. We could show that activation at the protein level is accompanied by induction of NF-kappaB p65 mRNA expression. HUVEC also express the NF-kappaB inhibitor I kappaB-alpha (MAD-3). In the early phase of activation by Ni2+ and Co2+ ions, disappearance of I kappaB-alpha in the cytoplasm accompanied p65 translocation, followed by its gradual reappearence. Because I kappaB mRNA could be upregulated by NiCl2 as well as by a mixture of cytokines, we suggest that the replenishment of the inhibitor in the cytoplasm is caused by de novo I kappaB gene expression. In addition to the enhanced DNA-binding activity of NF-kappaB, another transcription factor, AP-1, was also augmented in HUVEC stimulated by NiCl2, CoCl2 or by proinflammatory mediators and the phorbol ester PMA. Fos protein is shown to be a component of the activated AP-1 complex, as determined by supershift analysis, suggesting that it consists of Jun/Fos heterodimers.

Journal of Biological Chemistry, Dec 1, 1991

Federal Republic of Germany Octamer sequence elements were analyzed for their capacity to induce ... more Federal Republic of Germany Octamer sequence elements were analyzed for their capacity to induce the 75 K "core" promoter in vivo. The U6 distal sequence element (DSE) which contains a consensus sequence octamer, was able to support efficient 75 K expression in vivo. In contrast, no such function could be attributed to the octamer-like element alone, which is present within the 7 s K DSE. However, conversion of this octamer-like element (ATTTaGCAT) to the octamer consensus sequence ATTTGCAT generated a potent DSE, even in the absence of the CACCC box, which constitutes the major functional element of the 75 K DSE. Both the consensus and the octamer-like sequences revealed no cooperativity with the CACCC box. Together, these results demonstrate that the octamer-like element of the wildtype 7 s K DSE is definitely not functional in vivo. Furthermore, our experiments indicate that in contrast to the RNA polymerase 11-transcribed small nuclear RNA genes, in intact cells a single functional DSE motif is necessary and sufficient for maximal transcription by RNA polymerase I11 of the 7s K RNA gene.

PubMed, Apr 1, 2014

Social isolation and loneliness increase the risk of death as much as well-established risk facto... more Social isolation and loneliness increase the risk of death as much as well-established risk factors for mortality such as cigarette smoking and alcohol consumption. The underlying molecular mechanisms are poorly understood. In the present study, 3 months old male C57BL/6 mice were socially isolated by individual housing for another 3 months. At the age of 6 months, epigenetic changes were analyzed in midbrain. Social isolation of male adult mice led to an increased global DNA methylation, which was associated with enhanced activity of DNA methyltransferase. Di- and trimethylation of global histone H3 lysine 4 (H3K4) were increased in midbrain of socially isolated mice, accompanied by enhanced H3K4 histone methyltransferase activity. In addition, social isolation of adult mice led to activation of histone acetyltransferases as well as of histone deacetylases (HDAC) resulting in a net enhancement of histone H3 lysine 9 (H3K9) acetylation. Gene-specific effects were observed for Hdac1, Hdac3 and the serotonin transporter Slc6a4. Social isolation led to an up-regulation of Hdac1 and Hdac3, associated with decreased DNA methylation in the CpG island of the respective genes. On the contrary, the Slc6a4 gene was down-regulated, which was associated with enhanced DNA methylation. Collectively, the results from the present study demonstrate for the first time that social isolation of adult mice leads to a wide range of global epigenetic changes and these effects may have profound impact on gene expression pattern and phenotype of the socially isolated animals.

Scientific Reports, Oct 21, 2015

Interleukin (IL)-22 is a STAT3-activating cytokine displaying characteristic AU-rich elements (AR... more Interleukin (IL)-22 is a STAT3-activating cytokine displaying characteristic AU-rich elements (ARE) in the 3′-untranslated region (3′-UTR) of its mRNA. This architecture suggests gene regulation by modulation of mRNA stability. Since related cytokines undergo post-transcriptional regulation by ARE-binding tristetraprolin (TTP), the role of this destabilizing protein in IL-22 production was investigated. Herein, we demonstrate that TTP-deficient mice display augmented serum IL-22. Likewise, IL-22 mRNA was enhanced in TTP-deficient splenocytes and isolated primary T cells. A pivotal role for TTP is underscored by an extended IL-22 mRNA half-life detectable in TTP-deficient T cells. Luciferase-reporter assays performed in human Jurkat T cells proved the destabilizing potential of the human IL-22-3′-UTR. Furthermore, overexpression of TTP in HEK293 cells substantially decreased luciferase activity directed by the IL-22-3′-UTR. Transcript destabilization by TTP was nullified upon cellular activation by TPA/A23187, an effect dependent on MEK1/2 activity. Accordingly, IL-22 mRNA half-life as determined in TPA/A23187-stimulated Jurkat T cells decreased under the influence of the MEK1/2 inhibitor U0126. Altogether, data indicate that TTP directly controls IL-22 production, a process counteracted by MEK1/2. The TTP-dependent regulatory pathway described herein likely contributes to the role of IL-22 in inflammation and cancer and may evolve as novel target for pharmacological IL-22 modulation.

ChemInform, Oct 14, 2008

Other bioactive products U 1300 Inhibitors of Inducible NO Synthase Expression: Total Synthesis o... more Other bioactive products U 1300 Inhibitors of Inducible NO Synthase Expression: Total Synthesis of (S)-Curvularin (Ia) and Its Ring Homologues.-The derivatives (II) show improved downregulation of iNOS expression and almost no negative effects on eNOS expression as is desirable for antiinflammatory drugs.

PLOS ONE, Jun 15, 2015

<p>RNA isolated from aortas of ApoE-deficient mice either fed for 18 weeks with normal chow... more <p>RNA isolated from aortas of ApoE-deficient mice either fed for 18 weeks with normal chow diet (ND) or western-type diet (WD) (treated with Galiellalactone (Gal) or vehicle (PBS/EtOH) for 6 weeks) was analyzed for CTSS (<b>A</b>), SPP1 (<b>B</b>), TNFα (<b>C</b>), S100A8 (<b>D</b>), iNOS (<b>E</b>), IL6 (<b>F</b>), and IL17 (<b>G</b>) mRNA expression in qPCR experiments. Data shown are mean + SEM of 4–10 mice (*** = p < 0.001; ** = p < 0.01; * = p < 0.05; ns = not significant vs. WD + PBS/EtOH; one-way ANOVA).</p

Molecular Immunology, Jul 1, 2017

The KH type splicing regulatory protein (KSRP) is a nucleic acid binding protein, which negativel... more The KH type splicing regulatory protein (KSRP) is a nucleic acid binding protein, which negatively regulates the stability and/or translatability of many mRNA species encoding immune-relevant proteins. As KSRP is expressed in immune cells including T and B cells, neutrophils, macrophages and dendritic cells, we wanted to analyze its importance for the development of autoimmune diseases. We chose collagen antibody-induced arthritis (CAIA) as an appropriate autoimmune disease mouse model in which neutrophils and macrophages constitute the main effector cell populations. We compared arthritis induction in wild type (WT) and KSRP −/− mice and paws were taken for histological sections and qPCR analysis. Furthermore, we determined the frequencies of spleen immune cells by flow cytometry. Cytokine levels in spleen cell supernatants were determined by cytometric bead array analyses (CBA). After CAIA induction we unexpectedly observed in WT animals much stronger swelling of the paws than in KSRP −/− mice. In accordance, histological staining of paw sections of KSRP −/− animals revealed much lower frequencies of infiltrating immune cells in the joints compared to WT animals. Furthermore, CAIA-treatment resulted in reduced expression of several inflammatory factors (like CXCL-1, iNOS, TNF-α and S100A8) as well as immune cell marker genes (e.g. LFA-1, CD68, Ly6G) in the joints of KSRP −/− mice. Spleen cells of KSRP −/− mice showed lower frequencies of myeloid cells. On cytokine level IFN-γ production was increased in spleen cells of KSRP −/− mice compared to WT samples. These data surprisingly suggest that the absence of KSRP protects against the induction of inflammatory arthritis.

British Journal of Pharmacology, Oct 1, 2000

The therapeutic use of the antifungal drug amphotericin B (AmB) is limited due to severe side eec... more The therapeutic use of the antifungal drug amphotericin B (AmB) is limited due to severe side eects like glomerular vasoconstriction and risk of renal failure during AmB administration. As nitric oxide (NO) has substantial functions in renal autoregulation, we have determined the eects of AmB on endothelial constitutive NO synthase (ecNOS) expression and activity in human and rat endothelial cell cultures. 2 AmB used at concentrations of 0.6 to 1.25 mg ml 71 led to increases in ecNOS mRNA and protein expression as well as NO production. This was the result of an increased ecNOS mRNA half-life. In contrast, incubation of cells with higher albeit subtoxic concentrations of AmB (2.5 ± 5.0 mg ml 71) resulted in a decrease or respectively in completely abolished ecNOS mRNA and protein expression with a strongly reduced or inhibited ecNOS activity, due to a decrease of ecNOS mRNA half-life. None of the AmB concentrations aected promoter activity as found with a reporter gene construct stably transfected into ECV304 cells. 3 Thus, our experiments show a concentration-dependent biphasic eect of AmB on expression and activity of ecNOS, an eect best explained by AmB in¯uencing ecNOS mRNA stability. In view of the known renal accumulation of this drug the results reported here could help to elucidate its renal toxicity.

International Journal of Hypertension, 2012

Organic nitrates are a group of very effective anti-ischemic drugs. They are used for the treatme... more Organic nitrates are a group of very effective anti-ischemic drugs. They are used for the treatment of patients with stable angina, acute myocardial infarction, and chronic congestive heart failure. A major therapeutic limitation inherent to organic nitrates is the development of tolerance, which occurs during chronic treatment with these agents, and this phenomenon is largely based on induction of oxidative stress with subsequent endothelial dysfunction. We therefore speculated that induction of heme oxygenase-1 (HO-1) could be an efficient strategy to overcome nitrate tolerance and the associated side effects. Indeed, we found that hemin cotreatment prevented the development of nitrate tolerance and vascular oxidative stress in response to chronic nitroglycerin therapy. Vice versa, pentaerithrityl tetranitrate (PETN), a nitrate that was previously reported to be devoid of adverse side effects, displayed tolerance and oxidative stress when the HO-1 pathway was blocked pharmacologically or genetically by using HO-1 +/− mice. Recently, we identified activation of Nrf2 and HuR as a principle mechanism of HO-1 induction by PETN. With the present paper, we present and discuss our recent and previous findings on the role of HO-1 for the prevention of nitroglycerin-induced nitrate tolerance and for the beneficial effects of PETN therapy.

ChemMedChem, Jun 16, 2008

(S)‐Curvularin and its 13‐, 14‐, and 16‐membered lactone homologues were synthesized through a un... more (S)‐Curvularin and its 13‐, 14‐, and 16‐membered lactone homologues were synthesized through a uniform strategy in which a Kochi oxidative decarboxylation and ring‐closing metathesis reactions constitute the key processes. In the evaluation of the anti‐inflammatory effects of the synthesized compounds in assays using cells stably transfected with a human iNOS promoter–luciferase reporter gene construct, the 14‐ and 16‐membered homologues showed a slightly higher inhibitory effect towards iNOS promoter activity than curvularin itself. However, the larger ring homologues also exhibited higher cytotoxicity, manifest in downregulated eNOS promoter activity. In contrast, the di‐O‐acetyl and 4‐chloro derivatives of (S)‐curvularin showed higher inhibitory efficiency towards induction of the iNOS promoter and less negative effect on eNOS promoter activity than curvularin.

Proceedings of the National Academy of Sciences of the United States of America, Nov 9, 1999

Free Radical Biology and Medicine, May 1, 2023

Elsevier eBooks, 2007

Endothelial nitric oxide synthase (eNOS; also referred to as NOS3 or NOSIII), a low output enzyme... more Endothelial nitric oxide synthase (eNOS; also referred to as NOS3 or NOSIII), a low output enzyme is the prototypical isoform being found in endothelial cells. This isoform (like nNOS) synthesizes NO in a short-lasting, pulsatile, Ca++/calmodulin-activated manner. Endothelium-derived NO is a physiologically significant vasodilator and inhibitor of platelet aggregation and adhesion. In addition, vascular NO can prevent leukocyte adhesion to the endothelium by down-regulating the leukocyte adhesion glycoprotein complex CD11/CD18. Finally, endothelial NO has also been shown to inhibit the proliferation of vascular smooth muscle cells. Therefore, endothelial NO is likely to represent a protective anti-atherogenic principle. eNOS expression has also been demonstrated in several nonendothelial cell types such as neurons of the rat hippocampus and other rat brain regions; some epithelial cells; cardiomyocytes, megacaryocytes, and platelets; T cells; and others (for review see …

Nitric Oxide, Jul 1, 2019

Regulation of human inducible nitric oxide synthase expression by an upstream open reading frame,... more Regulation of human inducible nitric oxide synthase expression by an upstream open reading frame, Nitric Oxide (2019), doi:

PubMed, Sep 5, 2005

Human inducible NO synthase (iNOS) expression is regulated by post-transcriptional mechanisms. Th... more Human inducible NO synthase (iNOS) expression is regulated by post-transcriptional mechanisms. The 3'-untranslated region (3'-UTR) of the human iNOS mRNA contains AU-rich elements (ARE), which are known to be important for the regulation of mRNA stability. The 3'-UTR of the human iNOS mRNA has been shown to regulate human iNOS mRNA expression post-transcriptionally. One RNA-binding protein known to interact with AREs and to regulate mRNA stability is the T cell intracellular antigen-1-related protein (TIAR). In RNA binding studies TIAR displayed high affinity binding to the human iNOS 3'-UTR sequence. In RNase protection experiments, the cytokine incubation needed for iNOS expression did not change TIAR expression in DLD-1 cells. However, overexpression of TIAR in human DLD-1 colon carcinoma cells resulted in enhanced cytokine-induced iNOS expression. In conclusion, TIAR seems to be involved in the post-transcriptional regulation of human iNOS expression.

PLOS ONE, Jun 15, 2015

Patients suffering from chronic inflammatory diseases have an increased mortality risk resulting ... more Patients suffering from chronic inflammatory diseases have an increased mortality risk resulting from cardiovascular disorders due to enhanced atherosclerotic and thrombotic events. Until now, it is not completely understood in which way an abnormal expression of pro-inflammatory mediators contributes to this elevated cardiovascular risk, but there is a need for new drugs that on the one hand suppress the expression of pro-inflammatory mediators and on the other hand inhibit arterial platelet adhesion. Thus, we analyzed the anti-inflammatory and anti-thrombotic capacity of the fungal metabolite Galiellalactone in atherosclerosis-prone apolipoprotein E-deficient mice. Treatment of the mice with Galiellalactone lowered the inflammatory expression profile and improved blood clotting times, as well as platelet adhesion to the injured common carotid artery. The results indicate that administration of Galiellalactone is able to reduce the extent of inflammation and arterial platelet adhesion in this mouse model.

Molecular Pharmacology, Oct 1, 2002

We have investigated the impact of the widely used antifungal agent Amphotericin B (AmB) on cytok... more We have investigated the impact of the widely used antifungal agent Amphotericin B (AmB) on cytokine activated aortic endothelial cells (AEC) and their inflammatory response as monitored by cytokine and inducible nitric-oxide synthase (iNOS) expression as well as high-output nitric oxide synthesis. Because both blood-borne infections and systemically administered drugs will first encounter vessel lining endothelial cells, this cell type represents an important participant in innate immune reactions against xenobiotics. Culturing cytokine-activated AEC in the presence of 1.25 g/ml AmB, a concentration equivalent to serum levels during patient treatment, we find increases in iNOS promoter activity up to 120%, in iNOS mRNA or protein expressions by factors of up to 3.5 Ϯ 1.1, and in iNOS activity of up to 180% compared with cells with cytokines This work was supported by grant SFB503 A3 from the Deutsche Forschungsgemeinschaft (to V.K.-B.).

Journal of Biological Chemistry, May 1, 2014

Background: Chronic inflammatory diseases are associated with increased cardiovascular mortality ... more Background: Chronic inflammatory diseases are associated with increased cardiovascular mortality due to accelerated atherosclerosis. Results: Chronic inflammation in tristetraprolin (TTP)-deficient mice leads to endothelial dysfunction, which is related to enhanced Nox2-dependent reactive oxygen species production but independent from TNF-␣. Conclusion: Inflammation-related oxidative stress is an important mediator in inflammation-driven atherogenesis. Significance: In inflammatory diseases oxidative stress seems to be a major cause of cardiovascular events.

American Journal of Pathology, 2012

Echocardiographic analyses of this study were supported by the Federal Ministry of Education and ... more Echocardiographic analyses of this study were supported by the Federal Ministry of Education and Research (BMBF 01EO1003). The authors are responsible for the contents of this publication.

Pathobiology, 1997

We analyzed the influence of heavy-metal ions on human umbilical vein endothelial cells (HUVEC) i... more We analyzed the influence of heavy-metal ions on human umbilical vein endothelial cells (HUVEC) in comparison to proinflammatory cytokines (TNF-alpha, IL-1beta) and lipopolysaccharide (LPS). Adhesion molecule and cytokine expressions are upregulated by heavy-metal exposure. Expression of E-selectin on the cell surface was strongly induced by 1-mM concentrations of NiCl2 and CoCl2, whereas ZnCl2 and CrCl3 had no influence. Furthermore, it is shown that NiCl2 induces mRNA expression of E-selectin, intercellular adhesion molecule-1, IL-6 and IL-8 in a 1-mM concentration. The transcription factor NF-kappaB is known to be involved in the regulation of adhesion molecule expression in endothelial cells after activation by proinflammatory cytokines. We demonstrated that treatment of HUVEC with Ni2+ and Co2+ ions induces the translocation of NF-kappaB p65 and also p50 into the nucleus. NF-kappaB binding activity is enhanced under the influence of heavy metals as determined by mobility shift analysis. P65 and p50 are components of the NF-kappaB complexes as confirmed by supershift analysis. We could show that activation at the protein level is accompanied by induction of NF-kappaB p65 mRNA expression. HUVEC also express the NF-kappaB inhibitor I kappaB-alpha (MAD-3). In the early phase of activation by Ni2+ and Co2+ ions, disappearance of I kappaB-alpha in the cytoplasm accompanied p65 translocation, followed by its gradual reappearence. Because I kappaB mRNA could be upregulated by NiCl2 as well as by a mixture of cytokines, we suggest that the replenishment of the inhibitor in the cytoplasm is caused by de novo I kappaB gene expression. In addition to the enhanced DNA-binding activity of NF-kappaB, another transcription factor, AP-1, was also augmented in HUVEC stimulated by NiCl2, CoCl2 or by proinflammatory mediators and the phorbol ester PMA. Fos protein is shown to be a component of the activated AP-1 complex, as determined by supershift analysis, suggesting that it consists of Jun/Fos heterodimers.