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Jürgen Kraus

Publications and source records attributed to Jürgen Kraus.

17 recordsLinked to original sources
PubMed2006

Transcriptional regulation of the cannabinoid receptor type 1 gene in T cells by cannabinoids.

Effects of cannabinoids (CBs) are mediated by two types of receptors, CB1 and CB2. In this report, we investigated whether CBs regulate gene expression of their cognate receptors in T cells and studied underlying mechanisms in CD4+ Jurkat T cells. Transcription of the CB1 gene was strongly induced in response to Delta9-tetrahydrocannabinol (THC), whereas the CB2 gene was not regulated. The induction of CB1 gene expression is mediated by CB2 receptors only, as demonstrated by using the CB1 and CB2 agonists R(+)-methanandamide and JWH 015, respectively, and combinations of THC plus CB1- and CB2-specific antagonists. After activation of CB2 receptors, the transcription factor STAT5 is phosphorylated. STAT5 then transactivates IL-4. Induction of IL-4 mRNA as well as IL-4 protein release from the cells are necessary for the following induction of the CB1 gene. This was demonstrated by using decoy oligonucleotides against STAT5, which blocked IL-4 and CB1 mRNA induction, and by using the IL-4 receptor antagonist IL-4 [R121D,Y124D], which blocked the up-regulation of CB1 gene transcription. Transactivation of the CB1 gene in response to IL-4 is then mediated by the transcription factor STAT6, as shown by using decoy oligonucleotides against STAT6. An increase in CB1-mediated phosphorylation of MAPK in cells prestimulated with CB2-specific agonists suggests up-regulation of functional CB1 receptor proteins. In summary, up-regulation of CB1 in T lymphocytes in response to CBs themselves may facilitate or enhance the various immunomodulatory effects related to CBs.

Cannabinoids↗
PubMed2006

Interferon-gamma down-regulates transcription of the mu-opioid receptor gene in neuronal and immune cells.

Earlier investigations demonstrated up-regulated mu-opioid receptor expression in neuronal and immune cells in response to IL-1, IL-4, IL-6 and TNF-alpha. We herein report that mu-opioid receptor expression is down-regulated in SH SY5Y neuroblastoma cells by IFN-gamma, and that IL-4-mediated induction of mu-opioid receptor expression is inhibited in Jurkat T cells by IFN-gamma. Additionally, mu-opioid receptor transcripts were found in IL-4-expressing human primary T helper cells type 2, but not in type 1 cells, which typically express IFN-gamma. This indicates that mu-opioid receptor expression may be altered under conditions like inflammation, viral infections or neurological diseases associated with imbalanced cytokine expression.

Down-Regulation↗
PubMed2006

Cannabinoid receptor type 2 agonists induce transcription of the mu-opioid receptor gene in Jurkat T cells.

Opioids and cannabinoids are both associated with analgetic, psychotropic, and immunomodulatory effects. It has been suggested that both systems interact on multiple levels. We hypothesized that cannabinoids induce opioid receptors and investigated cannabinoid-dependent expression of the mu-opioid receptor subtype in a human T cell model. We report that activation of the peripheral cannabinoid receptor type 2 leads to a de novo induction of mu-opioid receptor transcription in Jurkat E6.1 cells. We show that interleukin-4 is transcriptionally induced in response to cannabinoids and that an interleukin-4 receptor antagonist blocks cannabinoid-dependent induction of mu-opioid receptors, indicating that induced expression of interleukin-4 is required in this process. Induction of interleukin-4 is blocked by decoy oligonucleotides directed against STAT5, indicating the requirement of this transcription factor. In addition, we show cannabinoid-dependent phosphorylation of STAT5. Further experiments demonstrate that interleukin-4 then induces phosphorylation of STAT6, which directly transactivates the mu-opioid receptor gene. In addition, STAT6 induces expression of the transcription factor GATA3, which also contributes to mu-opioid receptor gene transcription. The responsive promoter region of the human mu-opioid receptor gene with the binding sites for both factors was mapped to nt -1001 to -950. To demonstrate functional mu-opioid receptor proteins, morphine-mediated phosphorylation of mitogen-activated protein kinase was investigated. We show that phosphorylation of mitogen-activated protein kinase occurs only in cannabinoid-prestimulated Jurkat E6.1 cells and that it is blocked by the mu-opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2. In summary, these findings provide a first example for cannabinoid-opioid-interactions in cells of the immune system.

Base Sequence↗
PubMed2006

Micro-array analyses decipher exceptional complex familial chromosomal rearrangement.

Recently there has been an increased interest in large-scale genomic variation and clinically in the consequences of haploinsufficiency of genomic segments or disruption of normal gene function by chromosome rearrangements. Here, we present an extraordinary case in which both mother and daughter presented with unexpected chromosomal rearrangement complexity, which we characterized with array-CGH, array painting and multicolor large insert clone hybridizations. We found the same 12 breakpoints involving four chromosomes in both mother and daughter. In addition, the daughter inherited a microdeletion from her father. We mapped all breakpoints to the resolution level of breakpoint spanning clones. Genes were found within 7 of the 12 breakpoint regions, some of which were disrupted by the chromosome rearrangement. One of the rearrangements disrupted a locus, which has been discussed as a quantitative trait locus for fetal hemoglobin expression in adults. Interestingly, both mother and daughter show persistent fetal hemoglobin levels. We detail the most complicated familial complex chromosomal rearrangement reported to date and thus an extreme example of inheritance of chromosomal rearrangements without error in meiotic segregation.

Child↗
PubMed2004

Transcriptional regulation of the human mu-opioid receptor gene by interleukin-6.

Inflammatory pain is counteracted by a number of physiological processes. For example, opioid receptors, which are present on peripheral terminals of sensory neurons, are activated by endogenous opioids, which are released from immune cells migrating to the inflamed tissue. Earlier data demonstrated that interleukin-6 contributes to such inflammation-induced analgesia. In this report, we demonstrated that interleukin-6 strongly induces mu-opioid receptor mRNA in the human neuroblastoma cell line SH SY5Y, whereas delta-opioid receptor mRNA levels are not influenced. The mRNA increase in these cells is followed by an increase in mu-opioid receptor-specific binding. Using transcription factor decoy oligonucleotides, direct evidence was provided that the up-regulation of mu-opioid receptor mRNA in intact cells is dependent on the transcription factors signal transducers and activators of transcription 1 (STAT1) and STAT3, whereas other transcription factors, such as activator protein-1, nuclear factor (NF)-kappaB, or NF-interleukin-6 are not involved. STAT1 and STAT3 bound to a site located at nucleotide -1583 on the promoter of the human mu-opioid receptor gene, as shown by transient transfection experiments, electrophoretic mobility shift assays, and transcription factor decoy oligonucleotides. A mutation analysis of the 5'-TTCATGGAA-3' STAT1/3 element (palindrome underlined) was performed to determine nucleotide residues that are necessary for the binding of STAT1 and STAT3. It suggested that only the palindromic half sides and the two adjacent central nucleotides are required. Neither mutation of the nucleotides outside the palindrome nor mutation of the central nucleotide affected STAT1/3 binding.

Base Sequence↗
PubMed2004

Multicolor chromosome painting in diagnostic and research applications.

For many years whole chromosome painting probes have been the work-horses in a large variety of clinical and research molecular cytogenetic applications. In recent years painting probes have been complemented by an increasing number of further region-specific probes, which allow the specific staining of centromeres, subtelomeres or other regions within the genome. This development of new probe sets was greatly facilitated by the Human Genome Project from which well-characterized probes for any region within the genome have emerged. Furthermore, the evolution of different multicolor fluorescence in situ hybridization (FISH) technologies now allows the cohybridization of multiple DNA-probes of different colors. These developments have paved the way for FISH-based automated karyotyping or the simultaneous analysis of multiple defined regions within the genome. Using appropriate instrumentation and image processing, the analysis can be performed two-dimensionally on metaphase spreads or three-dimensionally in intact interphase nuclei. Here we summarize some of the most recent developments and discuss the application of painting probes in different scenarios.

Animals↗
PubMed2004

STAT6 transcription factor binding sites with mismatches within the canonical 5'-TTC...GAA-3' motif involved in regulation of delta- and mu-opioid receptors.

Opioid receptors are expressed in neuronal and immune cells and regulated in response to immunological processes. Herein, we demonstrate up-regulation of the delta-opioid receptor gene by interleukin-4 in immune cells (primary T and polymorphonuclear leukocytes, Jurkat E6 T cells), and in NG 108-15 neuronal cells. We identified an interleukin-4-responsive element at nt -671 on the murine gene promoter, to which the transcription factor STAT6 binds, as shown by reporter gene analysis and STAT6/DNA interaction studies in living cells with transcription factor decoy oligonucleotides. STAT6 normally binds to palindromic DNA motifs with a 5'-TTC...GAA-3' core. Notably, the delta-opioid receptor STAT6 site (5'-TTC...GGA-3') is an imperfect palindrome with a mismatch within this core sequence. A systematic analysis of possible mismatch 5'-TTC...GAA-3' motifs revealed that STAT6 also binds to the sequence 5'-TTA...GAA-3'. This motif occurs as a polymorphism in the human mu-opioid receptor gene (Kraus et al. 2001 J. Biol. Chem 276, 43901-43908). We show that this mutated element has a significantly reduced STAT6 binding activity which correlates to its reduced interleukin (IL)-4 inducibility. In contrast, the non-canonical STAT6 site of the delta-opioid receptor binds STAT6 with similar high activity as a perfectly palindromic STAT6 site and is strongly inducible by IL-4.

Amino Acid Motifs↗
PubMed2003

Hyper-recombination and genetic instability in BLM-deficient epithelial cells.

Genetic instability appears to be required for a normal colorectal epithelial cell to evolve into a cancerous one. Bloom syndrome patients have a strong predisposition to cancer that affects a variety of tissues. The mechanism of disease is attributed to genomic instability, but many questions about the nature of this instability have not yet been answered. To investigate these issues, we used gene-targeting techniques to disrupt the BLM gene in karyotypically stable colorectal cancer epithelial cells. BLM knockout cells showed an increased tendency of sister chromatids to exchange DNA strands and were substantially more likely to undergo homologous recombination at chromosomal loci than parental cells. Surprisingly, BLM-deficient colorectal cancer epithelial cells did not display gross chromosomal rearrangements nor a change in the rates of chromosome gains and losses. However, the enhanced homologous recombination was associated with losses of heterozygosity. These observations define a type of genetic instability that has significant implications for the evolution of cancer.

Adenosine Triphosphatases↗
PubMed2003

High-resolution genomic profiling of occult micrometastatic tumor cells.

Metastasis is responsible for most deaths from cancer. Currently, little is known about the early genetic events in the metastatic evolution. Here we describe the application of a newly developed strategy for an in-depth characterization of genomic changes in micrometastatic cells. Unique tumor cell lines were established from bone marrow of patients with cancer of the prostate and analyzed by multiplex-FISH (M-FISH) and array CGH. M-FISH revealed that the occult disseminated cells were characterized by very complex numerical and structural aberrations. Many of these aberrations resulted in chromosomal gains and losses, such as losses of 8p, 13q, and 18q and gains of 8q, 9q, 20, and the X chromosome, which are typically observed in prostate cancer. Array CGH allowed an unprecedented high-resolution assessment of copy number changes, pinpointing commonly gained or lost regions, which should narrow down the identification of regions critically involved in metastasis. Thus, occult micrometastatic cells are now amenable to detailed analyses of their genome. Markers for prognosis and treatment decisions can now be established.

Bone Marrow Cells↗
PubMed2003

The role of nuclear factor kappaB in tumor necrosis factor-regulated transcription of the human mu-opioid receptor gene.

Opioids and their receptors are key players in a cross-talk between the nervous and immune systems. For example, the endogenous opioid system is activated during inflammation as a physiological feedback mechanism to attenuate inflammatory pain. Herein, we report that in primary human T lymphocytes, Raji B cells, U937 monocytes, primary human polymorphonuclear leukocytes, and mature dendritic cells, the proinflammatory cytokine tumor necrosis factor induced mu-opioid receptor gene transcription. Transcriptional induction of the gene in immune cells was mediated via tumor necrosis factor receptor type 2. Using selective in vivo disruption of possibly involved transcription factors with decoy oligonucleotides, nuclear factor-kappaB was identified as the factor responsible for induction of the gene in immune cells, whereas activator protein-1 was found to be uninvolved. Nuclear factor-kappaB also mediates up-regulation of mu-opioid receptors in neuronal cells stimulated with tumor necrosis factor. Among six putative nuclear factor-kappaB binding sites on the mu-opioid receptor gene promoter, three cis-active elements at nt -2174, -557, and -207 were identified using transfection experiments of reporter gene constructs, electrophoretic mobility shift assays, and in vivo binding studies with decoy oligonucleotides. An allelic variation within the -557 element significantly reduced its trans-activating potency, which may affect regulation of the mu-opioid receptor gene in persons carrying this mutation. This study suggests a regulatory function of tumor necrosis factor in opioid-mediated processes in neuronal and immune cells, with possible impact on the complex of inflammation-induced analgesia.

Antigens, CD↗
PubMed2002

Distinct palindromic extensions of the 5'-TTC...GAA-3' motif allow STAT6 binding in vivo.

STATs (signal transducers and activators of transcription) are transcription factors downstream of cytokine and growth factor signals. All of the seven different STATs bind to regulatory promoter elements with the common core motif 5'-TTC(N)2-4GAA-3'. A key question is how the different STAT factors recognize "their" response elements, that is, what distinguishes for example STAT1 from STAT6 binding sites. In vivo, binding of the different STATs to DNA elements is highly specific and disruption of the genes for the different STAT factors is accompanied with distinct, non-overlaping phenotypical effects. As a first step towards discrimination of target sequences for the various STATs, we determined requirements for binding sites for STAT6. In functional assays, six sequences were identified. These have palindromic extensions of the core motif in common (underlined): 5'-TTTCNNNGAAA-3', 5'-CTTCNNNGAAG-3', 5'-TTTCNNNNGAAA-3', 5'-CTTCNNNNGAAG-3', 5'-TTCCNNGGAA-3' and 5'-TTCANNTGAA-3'. Different approaches and mutational analysis demonstrated the functionality of these sequences and high specific binding to STAT6. (I) These elements mediate transcriptional induction by interleukin-(IL)-4, IL-13, IL-15, and platelet-derived growth factor. (II) When used as "decoy" oligonucleotides, they bind STAT6 and disrupt its function in vivo, attenuating (a) STAT6/IL-4-mediated reporter gene transcription and (b) STAT6/IL-4-mediated induction of mu-opioid receptor mRNA of Raji cells.

Base Sequence↗
PubMed2002

Atropo-enantioselective total synthesis of knipholone and related antiplasmodial phenylanthraquinones.

The "lactone concept" has been efficiently employed for the first atropo-enantioselective synthesis of knipholone and related natural phenylanthraquinones. Besides the regio- and stereoselective construction of the biaryl axis, another important step was the "synthetically late" introduction of the C-acetyl group, either by a Friedel-Crafts type acetylation or by an ortho-selective Fries rearrangement first tested on simplified model systems and subsequently applied to the highly atroposelective preparation of the natural products and of simplified analogs thereof for biotesting. The synthetic availability of these natural biaryls, their precursors, and their unnatural analogs permitted a broader investigation of the antiplasmodial activities of these interesting biaryls.

Acetylation↗
PubMed2002

Rewarding effects of ethanol and cocaine in mu opioid receptor-deficient mice.

To investigate the role of mu opioid receptors in the reinforcing effects of psychotropic drugs, the voluntary ethanol intake and ethanol- and cocaine-induced conditioned place preference in mu opioid receptor-deficient mice and their wild-type counterpartners was tested. Moreover, dopamine D1 and D2 receptor binding was measured. It was found that ethanol intake was significantly lower in deficient mice. Conditioned place preference in wild-type animals was induced with 5.0 mg/kg cocaine and this dose was ineffective in the knockouts. In this group conditioned place preference occurred after injection of 10.0 mg/kg cocaine. Cocaine induced a similar increase in locomotor activity in both groups of mice. There was no difference in dopamine D1 receptor binding, whereas dopamine D2 receptor binding was significantly lower in the hippocampus of deficient animals. This suggests that interaction between opioid systems and dopaminergic systems may account for the differences in responding to the drugs.

Animals↗
PubMed2002

Small-sized low-density lipoproteins of subclass B from patients with end-stage renal disease effectively augment tumor necrosis factor-alpha-induced adhesive properties in human endothelial cells.

Increased prevalence of small-sized low-density lipoprotein (LDL) subclass B (diameter < 25.5 nm) possibly is involved in the multifactorial process of cardiovascular disease in patients with end-stage renal disease. Given these epidemiological observations, mechanisms underlying the combined effect of a proinflammatory insult and LDL of different subclasses (subclass A, diameter > 25.5 nm, and subclass B) in a cellular model were investigated. For this, human umbilical vein endothelial cells were preexposed to LDL, then stimulated with tumor necrosis factor-alpha (TNF-alpha). Modulatory effects of LDL phenotypes on the activation of adhesion molecules, monocyte adherence, and transcriptional activity of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) were investigated. Our data show that subclass B LDLs were metabolized through nonspecific scavenger receptors and specific LDL-receptor pathways in endothelial cells. Furthermore, LDL subclass B in comparison to subclass A more effectively enhanced monocyte recruitment and adhesive properties of endothelial cells in response to TNF-alpha. These effects appeared not to be mediated by oxidative stress-responsive NF-kappaB because modulation of this transcription factor by LDL was moderate and similar for both LDL phenotypes. Conversely, effects of LDL subclass B were considered to be caused by augmented AP-1 binding activity. In conclusion, the present model provides new clues in atherogenic mechanisms of small-sized LDLs, which sensitize vascular cells to inflammatory signals more effectively than normal-sized LDLs.

Cell Adhesion↗
PubMed2002

Involvement of activator protein-1 in transcriptional regulation of the human mu-opioid receptor gene.

mu-Opioid receptors mediate such opioid effects as analgesia, euphoria, and immunomodulation. Gene expression of mu-opioid receptors can be modulated by various substances, including cytokines, hormones, and drugs. Some of these stimuli (e.g., IL-1beta and cocaine) have been shown to activate members of the AP-1 transcription factor family. In addition, transcription of the mu-opioid receptor gene is induced by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C, which in turn is an activator of AP-1 transcription factors. This indicates that signaling pathways involving protein kinase C and activator protein 1 (AP-1) transcription factors are important for the specific expression pattern of the mu-opioid receptor gene. In this report, we show that TPA activates AP-1 as well as the transcription factor nuclear factor kappaB (NFkappaB) in the mu-opioid receptor expressing neuroblastoma cell line SH SY5Y. In transfection experiments performed in these cells, both factors trans-activate expression of reporter gene constructs containing the human mu-opioid receptor gene promoter. By excluding the effects of TPA on NFkappaB with the specific NFkappaB inhibitor sulfasalazine, AP-1 regulatory elements were localized. Two AP-1 elements, which differ in one nucleotide each from the classic AP-1 binding site, were delineated to positions -2388 and -1434 of the promoter. Independent of their orientation, these elements conferred TPA responsiveness on the heterologous thymidine kinase promoter. AP-1 binding to these elements was confirmed using electrophoretic mobility shift and immunoshift assays.

Cells, Cultured↗