Stat3/Socs3 activation by IL-6 transsignaling promotes progression of pancreatic intraepithelial neoplasia and development of pancreatic cancer

Physiological levels of Kras(G12D) are sufficient to induce pancreatic intraepithelial neoplasias (PanINs); the mechanisms that drive PanIN progression are unknown. Here, we establish that, in addition to oncogenic Kras(G12D), IL-6 transsignaling-dependent activation of Stat3/Socs3 is required to promote PanIN progression and pancreatic ductal adenocarcinoma (PDAC). Myeloid compartment induces Stat3 activation by secreting IL-6; consequently, IL-6 transsignaling activates Stat3 in the pancreas. Using genetic tools, we show that inactivation of IL-6 transsignaling or Stat3 inhibits PanIN progression and reduces the development of PDAC. Aberrant activation of Stat3 through homozygous deletion of Socs3 in the pancreas accelerates PanIN progression and PDAC development. Our data describe the involvement of IL-6 transsignaling/Stat3/Socs3 in PanIN progression and PDAC development.

CD25+/Foxp3+ T cells regulate gastric inflammation and Helicobacter pylori colonization in vivo

BACKGROUND & AIMS

Helicobacter pylori infects more than half of the world's population. In contrast to most other pathogens, the microbe persists for the virtual life of its host. It is unclear why the immune system is unable to eliminate the infection, but recent studies suggested that CD4+/CD25+/Foxp3+ regulatory T cells may be involved in this process.

METHODS

By using a mouse model of infection and gastric biopsies from 108 patients, we performed a detailed descriptive and functional characterization of the Helicobacter-induced CD25+/Foxp3+ T-cell response.

RESULTS

In C57BL/6 mice, H pylori induced a marked gastric Foxp3+ T-cell response, which increased over several months together with the severity of inflammation, until a stable homeostatic situation became established. Accordingly, in Helicobacter-infected patients, but not in uninfected individuals, large numbers of gastric Foxp3+ T cells were detected immunohistochemically. To define the functional in vivo relevance of this response, CD25+ cells were depleted systemically in mice by using an anti-CD25 monoclonal antibody (PC61). Already 4 weeks after infection, PC61-treated mice, but not untreated animals, developed a severe gastritis with heightened cytokine expression and increased numbers of mucosal T cells, B cells, and macrophages. This was accompanied by increased titers of H pylori-specific IgG1 and IgG2c antibodies in the sera of PC61-treated mice. This increased gastric inflammatory response in CD25-depleted mice was associated with reduced bacterial loads.

CONCLUSIONS

CD25+/Foxp3+ T cells actively participate in the immune response to H pylori. In vivo depletion of these cells in infected mice leads to increased gastric inflammation and reduced bacterial colonization.

Inhibition of polo-like kinase 1 by blocking polo-box domain-dependent protein-protein interactions

The serine/threonine kinase Polo-like kinase 1 (Plk1) is overexpressed in many types of human cancers, and has been implicated as an adverse prognostic marker for cancer patients. Plk1 localizes to its intracellular anchoring sites via its polo-box domain (PBD). Here we show that Plk1 can be inhibited by small molecules which interfere with its intracellular localization by inhibiting the function of the PBD. We report the natural product thymoquinone and, especially, the synthetic thymoquinone derivative Poloxin as inhibitors of the Plk1 PBD. Both compounds inhibit the function of the Plk1 PBD in vitro, and cause Plk1 mislocalization, chromosome congression defects, mitotic arrest, and apoptosis in HeLa cells. Our data validate the Plk1 PBD as an anticancer target and provide a rationale for developing thymoquinone derivatives as anticancer drugs.

Compartmentalized production of CCL17 in vivo: strong inducibility in peripheral dendritic cells contrasts selective absence from the spleen

Dendritic cells (DCs)(*) fulfill an important regulatory function at the interface of the innate and adaptive immune system. The thymus and activation-regulated chemokine (TARC/CCL17) is produced by DCs and facilitates the attraction of activated T cells. Using a fluorescence-based in vivo reporter system, we show that CCL17 expression in mice is found in activated Langerhans cells and mature DCs located in various lymphoid and nonlymphoid organs, and is up-regulated after stimulation with Toll-like receptor ligands. DCs expressing CCL17 belong to the CD11b(+)CD8(-)Dec205(+) DC subset, including the myeloid-related DCs located in the subepithelial dome of Peyer's patches. CCL17-deficient mice mount diminished T cell-dependent contact hypersensitivity responses and display a deficiency in rejection of allogeneic organ transplants. In contrast to lymphoid organs located at external barriers of the skin and mucosa, CCL17 is not expressed in the spleen, even after systemic microbial challenge or after in vitro stimulation. These findings indicate that CCL17 production is a hallmark of local DC stimulation in peripheral organs but is absent from the spleen as a filter of blood-borne antigens.

Helicobacter pylori HopH (OipA) and bacterial pathogenicity: genetic and functional genomic analysis of hopH gene polymorphisms

BACKGROUND

Expression of the Helicobacter pylori outer membrane protein HopH is regulated by phase variation within a CT dinucleotide repeat motif of the hopH gene.

METHODS

To investigate the importance of HopH for bacterial pathogenicity, we performed a detailed functional genomic and population-based genetic characterization of this contingency locus.

RESULTS

Sequencing of hopH in H. pylori strains from 58 patients revealed that the hopH "on" genotype is linked to bacterial virulence determinants, such as the vacAs1, vacAm1, babA2, and, most strongly, cagA genotypes. hopH mutagenesis resulted in reduced bacterial adherence to gastric epithelia in vitro. Complementation of hopH in trans restored the adherence properties of hopH mutants. Although HopH has been previously linked to proinflammatory epithelial signaling, hopH mutagenesis did not alter epithelial interleukin-8 secretion in vitro. Comparative epithelial gene-expression profiling by cDNA microarrays revealed no significant differences between the wild-type-specific and hopH mutant-specific transcriptomes. By contrast, a large set of genes was differentially regulated in a cag pathogenicity island-dependent manner.

CONCLUSION

An in-frame hopH gene may be linked to gastroduodenal diseases because of its association with other virulence factors or increased bacterial adherence and colonization. The strong linkage with cagA indicates that HopH may contribute to the fitness of cagA-positive strains in vivo.

Requirement of Toll-like receptor 7 for pristane-induced production of autoantibodies and development of murine lupus nephritis

OBJECTIVE

The detection of high titers of antibodies against small nuclear ribonucleoproteins (snRNP) is a diagnostic finding in patients in whom systemic lupus erythematosus (SLE) is suspected. Endogenous RNA molecules within snRNP trigger Toll-like receptor 7 (TLR-7) activation in B cells and dendritic cells, leading to anti-snRNP antibody production, which is associated with the development of immune complex nephritis in SLE. The purpose of this study was to investigate the role of TLR-7 in anti-snRNP antibody production and renal disease in SLE induced by an exogenous factor in the absence of genetic predisposition, using the pristane-induced murine lupus model.

METHODS

Serum autoantibodies, IgG isotypes, and cytokine levels in pristane-treated wild-type and TLR-7-deficient mice were analyzed by enzyme-linked immunosorbent assay. Histopathologic changes in mouse kidneys were determined by light immunofluorescence microscopy. Cell subsets in splenocytes and peritoneal lavage cells from the mice were examined by flow cytometry.

RESULTS

We found that anti-snRNP antibody production induced by pristane treatment was entirely dependent on the expression of TLR-7, whereas anti-double-stranded DNA antibody production was not affected by a lack of TLR-7. Impaired anti-snRNP antibody production in TLR-7-deficient mice was paralleled by lower levels of glomerular IgG and complement deposits, as well as less severe glomerulonephritis.

CONCLUSION

TLR-7 is specifically required for the production of RNA-reactive autoantibodies and the development of glomerulonephritis in pristane-induced murine lupus, a model of environmentally triggered SLE in the absence of genetic susceptibility to autoimmunity. Specific interference with TLR-7 activation by endogenous TLR-7 ligands may therefore be a promising novel strategy for the treatment of SLE.

Human Dendritic Cells Respond toHelicobacter pylori, Promoting NK Cell and Th1-Effector Responses In Vitro

Helicobacter pylori infection leads to chronic gastric inflammation. The current study determined the response of human APCs, NK cells, and T cells toward the bacteria in vitro. Human monocyte-derived dendritic cells (DC) were incubated with bacteria for 48 h. Intact H. pylori at a multitude of infection 5 stimulated the expression of MHC class II (4- to 7-fold), CD80, and CD86 B7 molecules (10- to 12-fold) and the CD83 costimulatory molecule (>30-fold) as well as IL-12 secretion (>50-fold) in DCs, and thereby, strongly induced their maturation and activation. CD56(+)/CD4(-) NK cells, as well as CD4(+)/CD45RA(+) naive T cells, were isolated and incubated with DCs pulsed with intact bacteria or different cellular fractions. Coculture of H. pylori-pulsed DCs with NK cells strongly potentiated the secretion of TNF-alpha and IFN-gamma. Coculture of naive T cells with H. pylori-pulsed DCs significantly enhanced TNF-alpha, IFN-gamma, and IL-2 secretion as well as T-bet mRNA levels, while GATA-3 mRNA was lowered. However, the effect appeared attenuated compared with coculture with Escherichia coli. A greater stimulation was seen with naive T cells and DCs pulsed with H. pylori membrane preparations. Intact H. pylori potently induced the maturation and activation of human monocyte-derived DC and thereby promote NK and Th1 effector responses. The strong activation of NK cells may be important for the innate immune response. Th1-polarized T cells were induced especially by incubation with membrane preparations of H. pylori, suggesting that membrane proteins may account for the specific adaptive immune response.

CCL17 promotes intestinal inflammation in mice and counteracts regulatory T cell-mediated protection from colitis

BACKGROUND & AIMS

Priming of T cells by dendritic cells (DCs) in the intestinal mucosa and associated lymphoid tissues helps maintain mucosal tolerance but also contributes to the development of chronic intestinal inflammation. Chemokines regulate the intestinal immune response and can contribute to pathogenesis of inflammatory bowel diseases. We investigated the role of the chemokine CCL17, which is expressed by conventional DCs in the intestine and is up-regulated during colitis.

METHODS

Colitis was induced by administration of dextran sodium sulfate (DSS) to mice or transfer of T cells to lymphopenic mice. Colitis activity was monitored by body weight assessment, histologic scoring, and cytokine profile analysis. The direct effects of CCL17 on DCs and the indirect effects on differentiation of T helper (Th) cells were determined in vitro and ex vivo.

RESULTS

Mice that lacked CCL17 (Ccl17(E/E) mice) were protected from induction of severe colitis by DSS or T-cell transfer. Colonic mucosa and mesenteric lymph nodes from Ccl17-deficient mice produced lower levels of proinflammatory cytokines. The population of Foxp3(+) regulatory T cells (Tregs) was expanded in Ccl17(E/E) mice and required for long-term protection from colitis. CCR4 expression by transferred T cells was not required for induction of colitis, but CCR4 expression by the recipients was required. CCL17 promoted Toll-like receptor-induced secretion of interleukin-12 and interleukin-23 by DCs in an autocrine manner, promoted differentiation of Th1 and Th17 cells, and reduced induction of Foxp3(+) Treg cells.

CONCLUSIONS

The chemokine CCL17 is required for induction of intestinal inflammation in mice. CCL17 has an autocrine effect on DCs that promotes production of inflammatory cytokines and activation of Th1 and Th17 cells and reduces expansion of Treg cells.

Polo-box domain inhibitor poloxin activates the spindle assembly checkpoint and inhibits tumor growth in vivo

Polo-like kinase 1 (Plk1) is widely established as one of the most promising targets in oncology. Although the protein kinase domain of Plk1 is highly conserved, the polo-box domain (PBD) of Plk1 provides a much more compelling site to specifically inhibit the localization and target binding of Plk1. We recently identified, via fluorescence polarization assay, the natural product derivative, Poloxin, as the first small-molecule inhibitor specifically targeting the function of the Plk1 PBD. In this study, we characterized its mitotic phenotype and its function in vitro and in vivo. Poloxin induces centrosome fragmentation and abnormal spindle and chromosome misalignment, which activate the spindle assembly checkpoint and prolong mitosis. Notably, centrosomal fragmentation induced by Poloxin is partially attributable to dysfunctional Kizuna, a key substrate of Plk1 at centrosomes. Moreover, Poloxin strongly inhibits proliferation of a panel of cancer cells by inducing mitotic arrest, followed by a surge of apoptosis. More important, we report, for the first time to our knowledge, that the PBD inhibitor, Poloxin, significantly suppresses tumor growth of cancer cell lines in xenograft mouse models by lowering the proliferation rate and triggering apoptosis in treated tumor tissues. The data highlight that targeting the PBD by Poloxin is a powerful approach for selectively inhibiting Plk1 function in vitro and in vivo.

EchoBASE: an integrated post-genomic database for Escherichia coli

EchoBASE (http://www.ecoli-york.org) is a relational database designed to contain and manipulate information from post-genomic experiments using the model bacterium Escherichia coli K-12. Its aim is to collate information from a wide range of sources to provide clues to the functions of the approximately 1500 gene products that have no confirmed cellular function. The database is built on an enhanced annotation of the updated genome sequence of strain MG1655 and the association of experimental data with the E.coli genes and their products. Experiments that can be held within EchoBASE include proteomics studies, microarray data, protein–protein interaction data, structural data and bioinformatics studies. EchoBASE also contains annotated information on ‘orphan’ enzyme activities from this microbe to aid characterization of the proteins that catalyse these elusive biochemical reactions.

Antigen delivery to plasmacytoid dendritic cells via BST2 induces protective T cell-mediated immunity

Plasmacytoid dendritic cells (PDCs) are capable of presenting Ags to T cells in a tolerogenic or immunogenic manner depending on the formulation of the Ag and the mode of stimulation. It has not been investigated whether effective adaptive immune responses useful for vaccination can be induced by Ab-mediated Ag targeting to PDCs in vivo. In this study, we show that Ag delivered to murine PDCs via bone marrow stromal cell Ag 2 (BST2)/CD317 in combination with TLR agonists as adjuvants is specifically presented by PDCs in vivo and elicits strong cellular and humoral immune responses. These include IFN-γ production by CD4(+) T cells and high Ab titers with a broad range of IgG isotypes. In addition, BST2-mediated Ag delivery in the presence of polyinosinic-polycytidylic acid as adjuvant induces cytotoxic T lymphocytes that are functional in vivo. A single immunization with Ag-fused anti-BST2 Ab together with polyinosinic-polycytidylic acid as adjuvant is sufficient to trigger protective immunity against subsequent viral infection and tumor growth. We conclude that despite the potential tolerogenic properties of PDCs, Ag targeting to PDCs in combination with TLR agonists as adjuvants is an effective vaccination strategy.

BI 456906: Discovery and preclinical pharmacology of a novel GCGR/GLP-1R dual agonist with robust anti-obesity efficacy

OBJECTIVE

Obesity and its associated comorbidities represent a global health challenge with a need for well-tolerated, effective, and mechanistically diverse pharmaceutical interventions. Oxyntomodulin is a gut peptide that activates the glucagon receptor (GCGR) and glucagon-like peptide-1 receptor (GLP-1R) and reduces bodyweight by increasing energy expenditure and reducing energy intake in humans. Here we describe the pharmacological profile of the novel glucagon receptor (GCGR)/GLP-1 receptor (GLP-1R) dual agonist BI 456906.

METHODS

BI 456906 was characterized using cell-based in vitro assays to determine functional agonism. In vivo pharmacological studies were performed using acute and subchronic dosing regimens to demonstrate target engagement for the GCGR and GLP-1R, and weight lowering efficacy.

RESULTS

BI 456906 is a potent, acylated peptide containing a C18 fatty acid as a half-life extending principle to support once-weekly dosing in humans. Pharmacological doses of BI 456906 provided greater bodyweight reductions in mice compared with maximally effective doses of the GLP-1R agonist semaglutide. BI 456906's superior efficacy is the consequence of increased energy expenditure and reduced food intake. Engagement of both receptors in vivo was demonstrated via glucose tolerance, food intake, and gastric emptying tests for the GLP-1R, and liver nicotinamide N-methyltransferase mRNA expression and circulating biomarkers (amino acids, fibroblast growth factor-21) for the GCGR. The dual activity of BI 456906 at the GLP-1R and GCGR was supported using GLP-1R knockout and transgenic reporter mice, and an ex vivo bioactivity assay.

CONCLUSIONS

BI 456906 is a potent GCGR/GLP-1R dual agonist with robust anti-obesity efficacy achieved by increasing energy expenditure and decreasing food intake.

A secreted low-molecular-weight protein from Helicobacter pylori induces cell-cycle arrest of T cells

BACKGROUND & AIMS

Although Helicobacter pylori is recognized by the human immune system, the bacteria are not eliminated and lead to a chronic inflammation of the gastric mucosa.

METHODS

We investigated the interaction of H. pylori with human lymphocytes. T and B lymphocytes were isolated from H. pylori-infected patients and stimulated with anti-CD3/CD28 or interleukin-6.

RESULTS

Proliferation of lymphocytes was abolished on co-incubation with different H. pylori strains (1-5 bacteria/cell) or with protein extracts of culture supernatants. Inhibition of proliferation was independent of known virulence factors. The factor is a protein or protein complex with an apparent molecular weight between 30 and 60 kilodaltons, clearly distinct from VacA. Although antigen-specific activation of T cells (as shown by nuclear factor of activated T cells [NFAT]-activation, interferon-gamma production, and CD25 or CD69 up-regulation) remained intact, cell-cycle analysis showed that S-phase entry of T cells was inhibited completely by H. pylori. Consequently, stimulated T cells arrested in the G1 phase of the cell cycle. Western blot analysis showed markedly reduced phosphorylation of the retinoblastoma protein (pRb), suggesting inhibition of G1 cyclin-dependent kinase activity. In line with this, activities of cyclin D3 and cyclin E were down-regulated, and levels of the cyclin-dependent kinase inhibitor p27Kip1 were increased. Mouse embryonic fibroblasts deficient in p27 showed a decrease in H. pylori-induced inhibition of cell proliferation, suggesting a central role for p27 in mediating H. pylori-induced G1 arrest.

CONCLUSIONS

Induction of cell-cycle arrest in lymphocytes may be of major significance for the chronic persistence of bacteria in the human stomach.

A pan-specific inhibitor of the polo-box domains of polo-like kinases arrests cancer cells in mitosis

Playing polo: Small-molecule inhibitors of polo-like kinase 1 are mostly ATP-competitive, and thus face enormous specificity hurdles. This communication explores the concept of inhibiting Plk1 with a small-molecule inhibitor of the protein-protein interactions required for Plk1 function.

Effects of plasma expansion with albumin and paracentesis on haemodynamics and kidney function in critically ill cirrhotic patients with tense ascites and hepatorenal syndrome: a prospective uncontrolled trial

Introduction

Circulatory dysfunction in cirrhotic patients may cause a specific kind of functional renal failure termed hepato-renal syndrome (HRS). It contributes to the high incidence of renal failure in cirrhotic intensive care unit (ICU) patients. Fluid therapy may aggravate renal failure by increasing ascites and intra-abdominal pressure (IAP). This study investigates the short-term effects of paracentesis on haemodynamics and kidney function in volume resuscitated patients with HRS.

Methods

Nineteen consecutive cirrhotic patients with HRS were studied. Circulatory parameters and renal function were analysed before and after plasma expansion and paracentesis. Haemodynamic monitoring was performed by transpulmonary thermodilution.

Results

After infusion of 200 ml of 20% human albumin solution, mean arterial pressure (MAP) and central venous pressure remained unchanged. Global end-diastolic volume index (GEDVI) increased from 791 ml m^-2 (693 to 862) (median and 25th to 75th percentile) to 844 ml m^-2 (751 to 933). Cardiac index (CI) increased from 4.1 l min^-1 m^-2 (3.6 to 5.0) to 4.7 l min^-1 m^-2 (4.0 to 5.8), whereas systemic vascular resistance index (SVRI) decreased from 1,422 dyn s cm^-5 m^-2 (1,081 to 1,772) to 1,171 dyn s cm^-5 m^-2 (893 to 1,705). Creatinine clearance (CC) and fractional excretion of sodium (FeNa) were not affected. During paracentesis, IAP decreased from 22 mmHg (18 to 24) to 9 mmHg (8 to 12). MAP decreased from 81 mmHg (74 to 100) to 80 mmHg (71 to 89), and CI increased from 4.1 l min^-1 m^-2 (3.2 to 4.3) to 4.2 l min^-1 m^-2 (3.6 to 4.7), whereas SVRI decreased from 1,639 dyn s cm^-5 m^-2 (1,168 to 2,037) to 1,301 dyn s cm^-5 m^-2 (1,124 to 1,751). CC during the 12-hour interval after paracentesis was significantly higher than during the 12 hours before (33 ml min^-1 (16 to 50) compared with 23 ml min^-1 (12 to 49)). CC remained elevated for the rest of the observation period. FeNa increased after paracentesis but returned to baseline levels after 24 hours.

Conclusion

Paracentesis with parameter-guided fluid substitution and maintenance of central blood volume may improve renal function and is safe in the treatment of ICU patients with hepato-renal failure.

Efficacy, safety and tolerability of vidofludimus in patients with inflammatory bowel disease: the ENTRANCE study

BACKGROUND

Vidofludimus (SC12267) is a novel oral immunomodulator inhibiting dihydroorotate dehydrogenase (DHODH) and the expression of proinflammatory cytokines including interleukin-17 (IL17A and IL17F) and interferon-gamma. The objective of the study was to explore the efficacy, safety and tolerability of vidofludimus in steroid-dependent inflammatory bowel disease (IBD).

METHODS

The open label uncontrolled ENTRANCE study (ClinicalTrials.gov NCT00820365) has been conducted at 13 study centers in Germany, Bulgaria and Romania. Thirty-four steroid-dependent patients with a confirmed diagnosis of Crohn's disease (CD) or ulcerative colitis (UC) were treated with a once daily 35mg oral dose of vidofludimus over 12weeks. Steroids were tapered during the first 8weeks followed by a steroid-free treatment period of 4weeks. Complete response was defined as steroid-free clinical remission at week 12; partial response was defined as being in remission at steroid dose equal or lower than the individual patient's threshold dose for relapse.

RESULTS

Of the thirty-four patients enrolled in this trial 26 were evaluable for primary efficacy assessment. After completion of the 12weeks treatment phase 8 out of 14 (57.1%) patients with CD and 6 out of 12 (50.0%) patients with UC were in steroid-free remission (complete responders). Another 4 (28.6%) patients in CD and 5 (41.7%) patients in UC were partial responders. Vidofludimus was well tolerated, no drug-related serious adverse events were observed.

CONCLUSIONS

This trial provides first evidence of clinical efficacy of vidofludimus in IBD. Although the safety and tolerability profile seems favorable, long-term controlled studies are needed to further investigate its potential as novel IBD therapy.

Development of a series of aryl pyrimidine kynurenine monooxygenase inhibitors as potential therapeutic agents for the treatment of Huntington's disease

We report on the development of a series of pyrimidine carboxylic acids that are potent and selective inhibitors of kynurenine monooxygenase and competitive for kynurenine. We describe the SAR for this novel series and report on their inhibition of KMO activity in biochemical and cellular assays and their selectivity against other kynurenine pathway enzymes. We describe the optimization process that led to the identification of a program lead compound with a suitable ADME/PK profile for therapeutic development. We demonstrate that systemic inhibition of KMO in vivo with this lead compound provides pharmacodynamic evidence for modulation of kynurenine pathway metabolites both in the periphery and in the central nervous system.

Quantification assays for total and polyglutamine-expanded huntingtin proteins

The expansion of a CAG trinucleotide repeat in the huntingtin gene, which produces huntingtin protein with an expanded polyglutamine tract, is the cause of Huntington's disease (HD). Recent studies have reported that RNAi suppression of polyglutamine-expanded huntingtin (mutant HTT) in HD animal models can ameliorate disease phenotypes. A key requirement for such preclinical studies, as well as eventual clinical trials, aimed to reduce mutant HTT exposure is a robust method to measure HTT protein levels in select tissues. We have developed several sensitive and selective assays that measure either total human HTT or polyglutamine-expanded human HTT proteins on the electrochemiluminescence Meso Scale Discovery detection platform with an increased dynamic range over other methods. In addition, we have developed an assay to detect endogenous mouse and rat HTT proteins in pre-clinical models of HD to monitor effects on the wild type protein of both allele selective and non-selective interventions. We demonstrate the application of these assays to measure HTT protein in several HD in vitro cellular and in vivo animal model systems as well as in HD patient biosamples. Furthermore, we used purified recombinant HTT proteins as standards to quantitate the absolute amount of HTT protein in such biosamples.

A high-throughput assay based on fluorescence polarization for inhibitors of the polo-box domain of polo-like kinase 1

The serine/threonine kinase polo-like kinase 1 (Plk1) is critically involved in multiple mitotic processes and has been established as an adverse prognostic marker for tumor patients. Plk1 localizes to its substrates and its intracellular anchoring sites via its polo-box domain (PBD), which is unique to the family of polo-like kinases. Therefore, inhibition of the Plk1 PBD has been suggested as an approach to the inhibition of Plk1 that circumvents specificity problems associated with the inhibition of the conserved adenosine triphosphate (ATP) binding pocket. Here we report on the development of a high-throughput assay based on fluorescence polarization that allows the discovery of small-molecule inhibitors of the Plk1 PBD. The assay is based on binding of the Plk1 PBD to a phosphothreonine-containing peptide comprising its optimal binding motif with a K(d) of 26+/-2 nM. It is stable with regard to dimethyl sulfoxide (DMSO) and time, and it has a Z' value of 0.73+/-0.06 in a 384-well format.

Intrinsic neural network dysfunction in quiescent Crohn's Disease

Psychological factors and comorbidities play an important role in inflammatory bowel diseases. Such comorbidity could be associated with a specific neural phenotype. Brain regions associated with emotion regulation and self-referential processing, including areas assigned to the “default mode network” (DMN), could be promising candidates in this regard. We investigated the functional integrity of multiple intrinsic neural networks in remitted patients with Crohn’s disease (CD) and sought to establish relationships between neural network connectivity and psychiatric symptoms. Fifteen CD patients in remission and 14 controls were investigated. We employed resting-state functional magnetic resonance imaging (fMRI) at 3 Tesla followed by a spatial Independent Component Analysis for fMRI data. Abnormal connectivity in CD patients was observed in DMN subsystems only (p < 0.05, cluster-corrected). Increased connectivity was found in the anterior cingulate and left superior medial frontal gyrus (aDMN) and the middle cingulate cortex (pDMN). Middle cingulate activity showed a significant association with anxiety scores in patients (p = 0.029). This study provides first evidence of selectively disrupted intrinsic neural network connectivity in CD and suggests abnormalities of self-referential neural networks. An increased sensitivity to self-related affective and somatic states in CD patients could account for these findings and explain a higher risk for anxiety symptoms.

From soil to structure, a novel dimeric β-glucosidase belonging to glycoside hydrolase family 3 isolated from compost using metagenomic analysis

A recent metagenomic analysis sequenced a switchgrass-adapted compost community to identify enzymes from microorganisms that were specifically adapted to switchgrass under thermophilic conditions. These enzymes are being examined as part of the pretreatment process for the production of "second-generation" biofuels. Among the enzymes discovered was JMB19063, a novel three-domain β-glucosidase that belongs to the GH3 (glycoside hydrolase 3) family. Here, we report the structure of JMB19063 in complex with glucose and the catalytic variant D261N crystallized in the presence of cellopentaose. JMB19063 is first structure of a dimeric member of the GH3 family, and we demonstrate that dimerization is required for catalytic activity. Arg-587 and Phe-598 from the C-terminal domain of the opposing monomer are shown to interact with bound ligands in the D261N structure. Enzyme assays confirmed that these residues are absolutely essential for full catalytic activity.