RelA/p65 is a molecular target for the immunosuppressive action of protein kinase A.

Stimulation of the protein kinase A (PKA) signalling pathway exerts an inhibitory effect on the proliferation of numerous cells, including T lymphocytes. In CD4+ T helper cells, stimulation of PKA leads to suppression of interleukin 2 (IL-2) induction, while induction of the genes coding for the lymphokines IL-4 and IL-5 is enhanced. We show that the differential effect of PKA activity on induction of the IL-2 and IL-4 genes is mediated through their promoters. One major target of the suppressive effect of PKA is the kappa B site in the IL-2 promoter. A kappa B site is missing in the IL-4 promoter. Mutations preventing factor binding to the IL-2 kappa B site result in a loss of PKA-mediated suppression of IL-2 promoter activity. Furthermore, activation of the PKA signalling pathway impairs the inducible activity of multiple kappa B sites of the IL-2 promoter, but not of other factor binding sites. The reduction in activity of kappa B sites in activated and PKA-stimulated T cells is accompanied by changes in the concentration and DNA binding of Rel/NF-kappa B factors. Stimulation of the PKA pathway in Jurkat T cells with the PKA activator forskolin leads to an increase in synthesis of c-Rel and p105/p50, while synthesis of p65/RelA remains unchanged. However, nuclear translocation and DNA binding of p65 is distinctly impaired, probably due to a retarded degradation of I kappa B-alpha. In a similar way, stimulation of the PKA signalling pathway inhibits nuclear translocation of p65 and generation of nuclear kappa B complexes in peripheral T lymphocytes from murine lymph nodes. These results indicate that PKA-mediated suppression of NF-kappa B activity plays an important role in the control of activation of peripheral T lymphocytes.     

PRMT1 promotes the tumor suppressor function of p14ARF and is indicative for pancreatic cancer prognosis

The p14^ARF protein is a well‐known regulator of p53‐dependent and p53‐independent tumor‐suppressive activities. In unstressed cells, p14^ARF is predominantly sequestered in the nucleoli, bound to its nucleolar interaction partner NPM. Upon genotoxic stress, p14^ARF undergoes an immediate redistribution to the nucleo‐ and cytoplasm, where it promotes activation of cell cycle arrest and apoptosis. Here, we identify p14^ARF as a novel interaction partner and substrate of PRMT1 (protein arginine methyltransferase 1). PRMT1 methylates several arginine residues in the C‐terminal nuclear/nucleolar localization sequence (NLS/NoLS) of p14^ARF. In the absence of cellular stress, these arginines are crucial for nucleolar localization of p14^ARF. Genotoxic stress causes augmented interaction between PRMT1 and p14^ARF, accompanied by arginine methylation of p14^ARF. PRMT1‐dependent NLS/NoLS methylation promotes the release of p14^ARF from NPM and nucleolar sequestration, subsequently leading to p53‐independent apoptosis. This PRMT1‐p14^ARF cooperation is cancer‐relevant and indicative for PDAC (pancreatic ductal adenocarcinoma) prognosis and chemotherapy response of pancreatic tumor cells. Our data reveal that PRMT1‐mediated arginine methylation is an important trigger for p14^ARF’s stress‐induced tumor‐suppressive function.     

Effects of intima stiffness and plaque morphology on peak cap stress

Background  

Rupture of the cap of a vulnerable plaque present in a coronary vessel may cause myocardial infarction and death. Cap rupture occurs when the peak cap stress exceeds the cap strength. The mechanical stress within a cap depends on the plaque morphology and the material characteristics of the plaque components. A parametric study was conducted to assess the effect of intima stiffness and plaque morphology on peak cap stress.     

Genetic association analyses of PDYN polymorphisms with heroin and cocaine addiction

Genetic factors are believed to account for 30-50% of the risk for cocaine and heroin addiction. Dynorphin peptides, derived from the prodynorphin (PDYN) precursor, bind to opioid receptors, preferentially the kappa-opioid receptor, and may mediate the aversive effects of drugs of abuse. Dynorphin peptides produce place aversion in animals and produce dysphoria in humans. Cocaine and heroin have both been shown to increase expression of PDYN in brain regions relevant for drug reward and use. Polymorphisms in PDYN are therefore hypothesized to increase risk for addiction to drugs of abuse. In this study, 3 polymorphisms in PDYN (rs1022563, rs910080 and rs1997794) were genotyped in opioid-addicted [248 African Americans (AAs) and 1040 European Americans (EAs)], cocaine-addicted (1248 AAs and 336 EAs) and control individuals (674 AAs and 656 EAs). Sex-specific analyses were also performed as a previous study identified PDYN polymorphisms to be more significantly associated with female opioid addicts. We found rs1022563 to be significantly associated with opioid addiction in EAs [P = 0.03, odds ratio (OR) = 1.31; false discovery rate (FDR) corrected q-value]; however, when we performed female-specific association analyses, the OR increased from 1.31 to 1.51. Increased ORs were observed for rs910080 and rs199774 in female opioid addicts also in EAs. No statistically significant associations were observed with cocaine or opioid addiction in AAs. These data show that polymorphisms in PDYN are associated with opioid addiction in EAs and provide further evidence that these risk variants may be more relevant in females.     

Fine mapping of a seizure susceptibility locus on mouse Chromosome 1: nomination of Kcnj10 as a causative gene

Previous quantitative trait loci (QTL) mapping studies document that the distal region of mouse Chromosome (Chr) 1 contains a gene(s) that is in large part responsible for the difference in seizure susceptibility between C57BL/6 (B6) (relatively seizure-resistant) and DBA/2 (D2) (relatively seizure-sensitive) mice. We now confirm this seizure-related QTL (Szs1) using reciprocal, interval-specific congenic strains and map it to a 6.6-Mb segment between Pbx1 and D1Mit150. Haplotype conservation between strains within this segment suggests that Szs1 may be localized more precisely to a 4.1-Mb critical interval between Fcgr3 and D1Mit150. We compared the coding region sequences of candidate genes between B6 and D2 mice using RT-PCR, amplification from genomic DNA, and database searching and discovered 12 brain-expressed genes with SNPs that predict a protein amino acid variation. Of these, the most compelling seizure susceptibility candidate is Kcnj10. A survey of the Kcnj10 SNP among other inbred mouse strains revealed a significant effect on seizure sensitivity such that most strains possessing a haplotype containing the B6 variant of Kcnj10 have higher seizure thresholds than those strains possessing the D2 variant. The unique role of inward-rectifying potassium ion channels in membrane physiology coupled with previous strong association between ion channel gene mutations and seizure phenotypes puts even greater focus on Kcnj10 in the present model. In summary, we confirmed a seizure-related QTL of large effect on mouse Chr 1 and mapped it to a finely delimited region. The critical interval contains several candidate genes, one of which, Kcnj10, exhibits a potentially important polymorphism with regard to fundamental aspects of seizure susceptibility.     

Murine IL-4 antagonizes the protective effects of IFN on virus-mediated lysis of murine L929 fibroblast cells.

IFN-alpha, -beta, and -gamma protect murine fibroblasts from lysis by vesicular stomatitis virus. In this report we show that culture supernatants derived from a Th cell clone of the TH2-type completely block the protective effects of the IFN. The active component in inhibiting IFN is identified to be IL-4. rIL-4 has similar effects as the T cell supernatant.     

The multidrug resistance protein 1: a functionally important activation marker for murine Th1 cells

Previously, we described the expression of an energy-dependent pump in resting murine Th2 (but not resting Th1) cells which extruded the fluorescent dye Fluo-3. After stimulation with Ag and APCs, Th1 cells also expressed this pump. Furthermore, expression of the murine multidrug resistance protein 1 (mrp1) correlated with the presence of the pump. In this study, we report that Fluo-3 is indeed transported by murine mrp1 or its human ortholog MRP1, as revealed by transfection of HEK 293 cells with mrp1 or MRP1 cDNA. Like antigenic activation, IL-2 dose-dependently enhanced the Fluo-3-extruding activity in murine Th1 cells. Although TNF-alpha and IL-12 by themselves only weakly enhanced Fluo-3 extrusion, each of them did so in strong synergism with IL-2. An Ab directed against mrp1 was used to quantify the expression of mrp1 protein in T cells at the single-cell level. Like the Fluo-3 pump, mrp1 protein expression was enhanced by IL-2. Immunohistochemical studies using confocal laser microscopy indicated that mrp1 is localized mainly at the plasma membrane. In addition, protein expression of mrp1 was induced in Vbeta8+CD4+ T cells 12 h after in vivo application of Staphylococcal enterotoxin B. Finally, mrp1 was functionally relevant during the activation process of Th1 cells, because T cell activation could be suppressed by exposure of cells to the mrp1 inhibitor MK571. Thus, we present mrp1 as a novel, functionally important activation marker for Th1 cells and short-term in vivo activated CD4+ T cells, whereas its expression seems to be constitutive in Th2 cells.     

Helicobacter pylori gastritis: a Th1 mediated disease?

Helicobacter pylori is now considered to be the main cause for most stomach diseases including ulcer, MALT lymphoma, adenocarcinoma and gastritis. The infection with this bacterium is chronic despite a local and systemic immune response towards it. Among the cellular infiltrate that arises during H. pylori-mediated gastritis, there is a considerable frequency of CD4+ Th1 cells producing IFNgamma, but not of Th2 cells producing IL-4. Since IFNgamma may induce binding of H. pylori to gastric epithelial cells followed by apoptosis of these cells, one may speculate that H. pylori-mediated diseases are in part autoimmune diseases initiated by H. pylori-specific Th1 cells infiltrating the gastric mucosa. Recent support for this hypothesis comes from an animal model in which mice are infected with H. pylori and display strongly reduced gastritis in the absence of IFNgamma.     

Genetic dissection of intermale aggressive behavior in BALB/cJ and A/J mice

Aggressive behaviors are disabling, treatment refractory, and sometimes lethal symptoms of several neuropsychiatric disorders. However, currently available treatments for patients are inadequate, and the underlying genetics and neurobiology of aggression is only beginning to be elucidated. Inbred mouse strains are useful for identifying genomic regions, and ultimately the relevant gene variants (alleles) in these regions, that affect mammalian aggressive behaviors, which, in turn, may help to identify neurobiological pathways that mediate aggression. The BALB/cJ inbred mouse strain exhibits relatively high levels of intermale aggressive behaviors and shows multiple brain and behavioral phenotypes relevant to neuropsychiatric syndromes associated with aggression. The A/J strain shows very low levels of aggression. We hypothesized that a cross between BALB/cJ and A/J inbred strains would reveal genomic loci that influence the tendency to initiate intermale aggressive behavior. To identify such loci, we conducted a genomewide scan in an F2 population of 660 male mice bred from BALB/cJ and A/J inbred mouse strains. Three significant loci on chromosomes 5, 10 and 15 that influence aggression were identified. The chromosome 5 and 15 loci are completely novel, and the chromosome 10 locus overlaps an aggression locus mapped in our previous study that used NZB/B1NJ and A/J as progenitor strains. Haplotype analysis of BALB/cJ, NZB/B1NJ and A/J strains showed three positional candidate genes in the chromosome 10 locus. Future studies involving fine genetic mapping of these loci as well as additional candidate gene analysis may lead to an improved biological understanding of mammalian aggressive behaviors.