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Sample records for 5-lipoxygenase activating protein

  1. 5-lipoxygenase and 5-lipoxygenase-activating protein gene polymorphisms, dietary linoleic acid, and risk for breast cancer.

    PubMed

    Wang, Jun; John, Esther M; Ingles, Sue Ann

    2008-10-01

    The n-6 polyunsaturated fatty acid 5-lipoxygenase pathway has been shown to play a role in the carcinogenesis of breast cancer. We conducted a population-based case-control study among Latina, African-American, and White women from the San Francisco Bay area to examine the association of the 5-lipoxygenase gene (ALOX5) and 5-lipoxygenase-activating protein gene (ALOX5AP) with breast cancer risk. Three ALOX5AP polymorphisms [poly(A) microsatellite, -4900 A>G (rs4076128), and -3472 A>G (rs4073259)] and three ALOX5 polymorphisms [Sp1-binding site (-GGGCGG-) variable number of tandem repeat polymorphism, -1279 G>T (rs6593482), and 760 G>A (rs2228065)] were genotyped in 802 cases and 888 controls. We did not find significant main effects of ALOX5 and ALOX5AP genotypes on breast cancer risk that were consistent across race or ethnicity; however, there was a significant interaction between the ALOX5AP -4900 A>G polymorphism and dietary linoleic acid intake (P=0.03). Among women consuming a diet high in linoleic acid (top quartile of intake, >17.4 g/d), carrying the AA genotype was associated with higher breast cancer risk (age- and race-adjusted odds ratio, 1.8; 95% confidence interval, 1.2-2.9) compared with carrying genotypes AG or GG. Among women consuming

  2. Distinct parts of leukotriene C{sub 4} synthase interact with 5-lipoxygenase and 5-lipoxygenase activating protein

    SciTech Connect

    Strid, Tobias; Svartz, Jesper; Franck, Niclas; Hallin, Elisabeth; Ingelsson, Bjoern; Soederstroem, Mats; Hammarstroem, Sven

    2009-04-17

    Leukotriene C{sub 4} is a potent inflammatory mediator formed from arachidonic acid and glutathione. 5-Lipoxygenase (5-LO), 5-lipoxygenase activating protein (FLAP) and leukotriene C{sub 4} synthase (LTC{sub 4}S) participate in its biosynthesis. We report evidence that LTC{sub 4}S interacts in vitro with both FLAP and 5-LO and that these interactions involve distinct parts of LTC{sub 4}S. FLAP bound to the N-terminal part/first hydrophobic region of LTC{sub 4}S. This part did not bind 5-LO which bound to the second hydrophilic loop of LTC{sub 4}S. Fluorescent FLAP- and LTC{sub 4}S-fusion proteins co-localized at the nuclear envelope. Furthermore, GFP-FLAP and GFP-LTC{sub 4}S co-localized with a fluorescent ER marker. In resting HEK293/T or COS-7 cells GFP-5-LO was found mainly in the nuclear matrix. Upon stimulation with calcium ionophore, GFP-5-LO translocated to the nuclear envelope allowing it to interact with FLAP and LTC{sub 4}S. Direct interaction of 5-LO and LTC{sub 4}S in ionophore-stimulated (but not un-stimulated) cells was demonstrated by BRET using GFP-5-LO and Rluc-LTC{sub 4}S.

  3. Expression, purification and crystallization of human 5-lipoxygenase-activating protein with leukotriene-biosynthesis inhibitors

    SciTech Connect

    Xu, Shihua; McKeever, Brian M.; Wisniewski, Douglas; Miller, Douglas K.; Spencer, Robert H.; Chu, Lin; Ujjainwalla, Feroze; Yamin, Ting-Ting; Evans, Jilly F.; Becker, Joseph W.; Ferguson, Andrew D.

    2007-12-01

    The expression, purification and crystallization of human 5-lipoxygenase-activating protein in complex with two leukotriene-biosynthesis inhibitors is decribed. The processes that were used to generate diffraction quality crystals are presented in detail. The nuclear membrane protein 5-lipoxygenase-activating protein (FLAP) plays an essential role in leukotriene synthesis. Recombinant full-length human FLAP with a C-terminal hexahistidine tag has been expressed and purified from the cytoplasmic membrane of Escherichia coli. Diffraction-quality crystals of FLAP in complex with leukotriene-synthesis inhibitor MK-591 and with an iodinated analogue of MK-591 have been grown using the sitting-drop vapor-diffusion method. The crystals exhibit tetragonal symmetry (P42{sub 1}2) and diffracted to a resolution limit of 4 Å.

  4. MK-886, an inhibitor of the 5-lipoxygenase-activating protein, inhibits cyclooxygenase-1 activity and suppresses platelet aggregation.

    PubMed

    Koeberle, Andreas; Siemoneit, Ulf; Northoff, Hinnak; Hofmann, Bettina; Schneider, Gisbert; Werz, Oliver

    2009-04-17

    MK-886, an inhibitor of the 5-lipoxygenase-activating protein (FLAP), potently suppresses leukotriene biosynthesis in intact cells and is frequently used to define a role of the 5-lipoxygenase (EC 1.13.11.34) pathway in cellular or animal models of inflammation, allergy, cancer, and cardiovascular disease. Here we show that MK-886 also interferes with the activities of cyclooxygenases (COX, EC 1.14.99.1). MK-886 inhibited isolated COX-1 (IC(50)=8 microM) and blocked the formation of the COX-1-derived products 12(S)-hydroxy-5-cis-8,10-trans-heptadecatrienoic acid (12-HHT) and thromboxane B(2) in washed human platelets in response to collagen as well as from exogenous arachidonic acid (IC(50)=13-15 microM). Isolated COX-2 was less affected (IC(50)=58 microM), and in A549 cells, MK-886 (33 microM) failed to suppress COX-2-dependent 6-keto-prostaglandin (PG)F(1alpha) formation. The distinct susceptibility of MK-886 towards COX-1 and -2 is apparent in automated molecular docking studies that indicate a preferred binding of MK-886 to COX-1 into the active site. MK-886 (10 microM) inhibited COX-1-mediated platelet aggregation induced by collagen or arachidonic acid whereas thrombin- or U-46619-induced (COX-independent) aggregation was not affected. Since leukotrienes and prostaglandins share (patho)physiological properties in the development and regulation of carcinogenesis, inflammation, and vascular functions, caution should be used when interpreting data where MK-886 is used as tool to determine the involvement of FLAP and/or the 5-lipoxygenase pathway in respective experimental models.

  5. Regulation of gamma-secretase activating protein by the 5Lipoxygenase: in vitro and in vivo evidence

    PubMed Central

    Chu, Jin; Li, Jian-Guo; Hoffman, Nicholas E.; Stough, Alexandra M.; Madesh, Muniswamy; Praticò, Domenico

    2015-01-01

    The formation of Aβ is directly controlled by the γ-secretase complex and its activator, γ-secretase activating protein (GSAP). GSAP derives from a C-terminal fragment of a larger precursor protein via a caspase-3 mediated cleavage. However, the mechanism regulating this process remains unknown. Here we provide in vitro experimental evidence that 5-Lipoxygenase (5LO) is as an endogenous regulator for GSAP formation, but not for other known γ-secretase modulators, by directly and specifically activating caspase-3. These results were confirmed in vivo by using transgenic mouse models of Alzheimer’s disease in which 5LO level and activity were modulated genetically or pharmacologically. Taken together, our findings demonstrate that GSAP cleavage via caspase-3 is regulated and depend upon the availability of 5LO further establishing this protein as an attractive and viable therapeutic target for Alzheimer’s disease. PMID:26076991

  6. 4,5-Diarylisoxazol-3-carboxylic acids: A new class of leukotriene biosynthesis inhibitors potentially targeting 5-lipoxygenase-activating protein (FLAP).

    PubMed

    Banoglu, Erden; Çelikoğlu, Erşan; Völker, Susanna; Olgaç, Abdurrahman; Gerstmeier, Jana; Garscha, Ulrike; Çalışkan, Burcu; Schubert, Ulrich S; Carotti, Andrea; Macchiarulo, Antonio; Werz, Oliver

    2016-05-01

    In this article, we report novel leukotriene (LT) biosynthesis inhibitors that may target 5-lipoxygenase-activating protein (FLAP) based on the previously identified isoxazole derivative (8). The design and synthesis was directed towards a subset of 4,5-diaryl-isoxazole-3-carboxylic acid derivatives as LT biosynthesis inhibitors. Biological evaluation disclosed a new skeleton of potential anti-inflammatory agents, exemplified by 39 and 40, which potently inhibit cellular 5-LO product synthesis (IC50 = 0.24 μM, each) seemingly by targeting FLAP with weak inhibition on 5-LO (IC50 ≥ 8 μM). Docking studies and molecular dynamic simulations with 5-LO and FLAP provide valuable insights into potential binding modes of the inhibitors. Together, these diaryl-isoxazol-3-carboxylic acids may possess potential as leads for development of effective anti-inflammatory drugs through inhibition of LT biosynthesis. PMID:26922224

  7. 5-Lipoxygenase Activating Protein Reduction Ameliorates Cognitive Deficit, Synaptic Dysfunction, and Neuropathology in a Mouse Model of Alzheimer’s Disease

    PubMed Central

    Giannopoulos, Phillip F.; Chu, Jin; Joshi, Yash B.; Sperow, Margaret; Li, Jin-Guo; Kirby, Lynn G.; Praticò, Domenico

    2013-01-01

    Background 5-lipoxygenase activating protein (FLAP) is abundantly present in the central nervous system. Although its function has been extensively interrogated in the context of peripheral inflammation, novel roles for this protein are emerging in the central nervous system. The objective of our study was to investigate the functional role that FLAP plays in a mouse model of Alzheimer’s disease (AD) with plaques and tangles (i.e., 3×Tg mice). Methods By implementing a genetic knockout of FLAP and pharmacologic inhibition with a FLAP inhibitor (MK-591), we evaluated the effect on the AD-like neuropathology, cognition, and synaptic plasticity in the 3×Tg mice. Results We show that reduction of FLAP leads to amelioration of cognition and memory along with the rescuing of synaptic dysfunction at an early age before the development of overt neuropathology. Genetic knockout and pharmacologic inhibition of FLAP also yielded an improvement in AD pathology through a reduction in Aβ via the γ-secretase pathway and a decrease in tau phosphorylation through the cdk5 pathway. Conclusions Our studies identify a novel functional role for FLAP in regulating memory and synaptic plasticity. They establish this protein at the crossroad of multiple pathways that ultimately contribute to the development of the entire AD-like phenotype, making it a viable therapeutic target with disease-modifying capacity for the treatment of this disease. PMID:23683389

  8. A Single Amino Acid Difference between Mouse and Human 5-Lipoxygenase Activating Protein (FLAP) Explains the Speciation and Differential Pharmacology of Novel FLAP Inhibitors.

    PubMed

    Blevitt, Jonathan M; Hack, Michael D; Herman, Krystal; Chang, Leon; Keith, John M; Mirzadegan, Tara; Rao, Navin L; Lebsack, Alec D; Milla, Marcos E

    2016-06-10

    5-Lipoxygenase activating protein (FLAP) plays a critical role in the metabolism of arachidonic acid to leukotriene A4, the precursor to the potent pro-inflammatory mediators leukotriene B4 and leukotriene C4 Studies with small molecule inhibitors of FLAP have led to the discovery of a drug binding pocket on the protein surface, and several pharmaceutical companies have developed compounds and performed clinical trials. Crystallographic studies and mutational analyses have contributed to a general understanding of compound binding modes. During our own efforts, we identified two unique chemical series. One series demonstrated strong inhibition of human FLAP but differential pharmacology across species and was completely inactive in assays with mouse or rat FLAP. The other series was active across rodent FLAP, as well as human and dog FLAP. Comparison of rodent and human FLAP amino acid sequences together with an analysis of a published crystal structure led to the identification of amino acid residue 24 in the floor of the putative binding pocket as a likely candidate for the observed speciation. On that basis, we tested compounds for binding to human G24A and mouse A24G FLAP mutant variants and compared the data to that generated for wild type human and mouse FLAP. These studies confirmed that a single amino acid mutation was sufficient to reverse the speciation observed in wild type FLAP. In addition, a PK/PD method was established in canines to enable preclinical profiling of mouse-inactive compounds. PMID:27129215

  9. A Single Amino Acid Difference between Mouse and Human 5-Lipoxygenase Activating Protein (FLAP) Explains the Speciation and Differential Pharmacology of Novel FLAP Inhibitors.

    PubMed

    Blevitt, Jonathan M; Hack, Michael D; Herman, Krystal; Chang, Leon; Keith, John M; Mirzadegan, Tara; Rao, Navin L; Lebsack, Alec D; Milla, Marcos E

    2016-06-10

    5-Lipoxygenase activating protein (FLAP) plays a critical role in the metabolism of arachidonic acid to leukotriene A4, the precursor to the potent pro-inflammatory mediators leukotriene B4 and leukotriene C4 Studies with small molecule inhibitors of FLAP have led to the discovery of a drug binding pocket on the protein surface, and several pharmaceutical companies have developed compounds and performed clinical trials. Crystallographic studies and mutational analyses have contributed to a general understanding of compound binding modes. During our own efforts, we identified two unique chemical series. One series demonstrated strong inhibition of human FLAP but differential pharmacology across species and was completely inactive in assays with mouse or rat FLAP. The other series was active across rodent FLAP, as well as human and dog FLAP. Comparison of rodent and human FLAP amino acid sequences together with an analysis of a published crystal structure led to the identification of amino acid residue 24 in the floor of the putative binding pocket as a likely candidate for the observed speciation. On that basis, we tested compounds for binding to human G24A and mouse A24G FLAP mutant variants and compared the data to that generated for wild type human and mouse FLAP. These studies confirmed that a single amino acid mutation was sufficient to reverse the speciation observed in wild type FLAP. In addition, a PK/PD method was established in canines to enable preclinical profiling of mouse-inactive compounds.

  10. Granulocyte/macrophage colony-stimulating factor stimulates the expression of the 5-lipoxygenase-activating protein (FLAP) in human neutrophils

    PubMed Central

    1994-01-01

    The synthesis of leukotrienes in human blood neutrophils chiefly relies on the activity of two enzymes, phospholipase A2 and 5-lipoxygenase (5- LO). In turn, the activation of the 5-LO requires the participation of a recently characterized membrane-bound protein, the 5-LO-activating protein (FLAP). In this study, we have investigated conditions under which FLAP expression in neutrophils may be modulated. Of several cytokines tested, only granulocyte/macrophage colony-stimulating factor (GM-CSF) (and to a lesser extent tumor necrosis factor alpha) significantly increased expression of FLAP. GM-CSF increased FLAP mRNA steady-state levels in a time- and dose-dependent manner. The stimulatory effect of GM-CSF on FLAP mRNA was inhibited by prior treatment of the cells with the transcription inhibitor, actinomycin D, and pretreatment of the cells with the protein synthesis inhibitor, cycloheximide, failed to prevent the increase in FLAP mRNA induced by GM-CSF. The accumulation of newly synthesized FLAP, as determined by immunoprecipitation after incorporation of 35S-labeled amino acids, was also increased after incubation of neutrophils with GM-CSF. In addition, the total level of FLAP protein was increased in GM-CSF- treated neutrophils, as determined by two-dimensional gel electrophoresis, followed by Western blot. GM-CSF did not alter the stability of the FLAP protein, indicating that the effect of GM-CSF on FLAP accumulation was the consequence of increased de novo synthesis as opposed to decreased degradation of FLAP. Finally, incubation of neutrophils with the synthetic glucocorticoid dexamethasone directly stimulated the upregulation of FLAP mRNA and protein, and enhanced the effect of GM-CSF. Taken together, these data demonstrate that FLAP expression may be upmodulated after appropriate stimulation of neutrophils. The increase in FLAP expression induced by GM-CSF in inflammatory conditions could confer upon neutrophils a prolonged capacity to synthesize

  11. Exploring the roles of UGT1A1 and UGT1A3 in oral clearance of GSK2190915, a 5-lipoxygenase-activating protein inhibitor.

    PubMed

    Mosteller, Michael; Condreay, Lynn D; Harris, Elizabeth C; Ambery, Claire; Beerahee, Misba; Ghosh, Soumitra

    2014-12-01

    Pharmacokinetic variability in drug exposure is a concern for all compounds in development including those for the treatment of asthma and other respiratory disorders. Substantial variability in the oral clearance of GSK2190915, a 5-lipoxygenase-activating protein inhibitor that attenuates the production of leukotriene B4 and cysteinyl leukotrienes, is largely unaccounted for by clinical variables. A study of 41 patients, 78% (32/41) of whom were non-Hispanic whites, with mild to moderate asthma identified an association of UGT1A1*28 and UGT1A3*2 with the oral clearance of GSK2190915 (P=3.8×10⁻⁴ and 1.2×10⁻⁵, respectively). However, in a subsequent replication study of 403 non-Hispanic white patients with asthma, we failed to observe a statistically significant association between oral clearance of GSK2190915 and either UGT1A1*28 or UGT1A3*2 (P>0.05). Therefore, genetic effects that could explain the systemic exposure level variability of GSK2190915 were not identified. PMID:25192553

  12. Phospholipid Ozonation Products Activate the 5-Lipoxygenase Pathway in Macrophages.

    PubMed

    Zemski Berry, Karin A; Murphy, Robert C

    2016-08-15

    Ozone is a highly reactive environmental toxicant that can react with the double bonds of lipids in pulmonary surfactant. This study was undertaken to investigate the proinflammatory properties of the major lipid-ozone product in pulmonary surfactant, 1-palmitoyl-2-(9'-oxo-nonanoyl)-glycerophosphocholine (16:0/9al-PC), with respect to eicosanoid production. A dose-dependent increase in the formation of 5-lipoxygenase (5-LO) products was observed in murine resident peritoneal macrophages (RPM) and alveolar macrophages (AM) upon treatment with 16:0/9al-PC. In contrast, the production of cyclooxygenase (COX) derived eicosanoids did not change from basal levels in the presence of 16:0/9al-PC. When 16:0/9al-PC and the TLR2 ligand, zymosan, were added to RPM or AM, an enhancement of 5-LO product formation along with a concomitant decrease in COX product formation was observed. Neither intracellular calcium levels nor arachidonic acid release was influenced by the addition of 16:0/9al-PC to RPM. Results from mitogen-activated protein kinase (MAPK) inhibitor studies and direct measurement of phosphorylation of MAPKs revealed that 16:0/9al-PC activates the p38 MAPK pathway in RPM, which results in the activation of 5-LO. Our results indicate that 16:0/9al-PC has a profound effect on the eicosanoid pathway, which may have implications in inflammatory pulmonary disease states where eicosanoids have been shown to play a role. PMID:27448436

  13. Inhibition of soluble epoxide hydrolase enhances the anti-inflammatory effects of aspirin and 5-lipoxygenase activation protein inhibitor in a murine model.

    PubMed

    Liu, Jun-Yan; Yang, Jun; Inceoglu, Bora; Qiu, Hong; Ulu, Arzu; Hwang, Sung-Hee; Chiamvimonvat, Nipavan; Hammock, Bruce D

    2010-03-15

    Inflammation is a multi-staged process whose expansive phase is thought to be driven by acutely released arachidonic acid (AA) and its metabolites. Inhibition of cyclooxygenase (COX), lipoxygenase (LOX), or soluble epoxide hydrolase (sEH) is known to be anti-inflammatory. Inhibition of sEH stabilizes the cytochrome P450 (CYP450) products epoxyeicosatrienoic acids (EETs). Here we used a non-selective COX inhibitor aspirin, a 5-lipoxygenase activation protein (FLAP) inhibitor MK886, and a sEH inhibitor t-AUCB to selectively modulate the branches of AA metabolism in a lipopolysaccharide (LPS)-challenged murine model. We used metabolomic profiling to simultaneously monitor representative AA metabolites of each branch. In addition to the significant crosstalk among branches of the AA cascade during selective modulation of COX, LOX, or sEH, we demonstrated that co-administration of t-AUCB enhanced the anti-inflammatory effects of aspirin or MK886, which was evidenced by the observations that co-administration resulted in favorable eicosanoid profiles and better control of LPS-mediated hypotension as well as hepatic protein expression of COX-2 and 5-LOX. Targeted disruption of the sEH gene displayed a parallel profile to that produced by t-AUCB. These observations demonstrate a significant level of crosstalk among the three major branches of the AA cascade and that they are not simply parallel pathways. These data illustrate that inhibition of sEH by both pharmacological intervention and gene knockout enhances the anti-inflammatory effects of aspirin and MK886, suggesting the possibility of modulating multiple branches to achieve better therapeutic effects. PMID:19896470

  14. Acrolein increases 5-lipoxygenase expression in murine macrophages through activation of ERK pathway

    SciTech Connect

    Kim, Chae E.; Lee, Seung J.; Seo, Kyo W.; Park, Hye M.; Yun, Jung W.; Bae, Jin U.; Bae, Sun S.; Kim, Chi D.

    2010-05-15

    Episodic exposure to acrolein-rich pollutants has been linked to acute myocardial infarction, and 5-lipoxygenase (5-LO) is involved in the production of matrix metalloproteinase-9 (MMP-9), which destabilizes atherosclerotic plaques. Thus, the present study determined the effect of acrolein on 5-LO/leukotriene B{sub 4} (LTB{sub 4}) production in murine macrophages. Stimulation of J774A.1 cells with acrolein led to increased LTB{sub 4} production in association with increased 5-LO expression. Acrolein-evoked 5-LO expression was blocked by pharmacological inhibition of the ERK pathway, but not by inhibitors for JNK and p38 MAPK pathways. In line with these results, acrolein exclusively increased the phosphorylation of ERK among these MAPK, suggesting a role for the ERK pathway in acrolein-induced 5-LO expression with subsequent production of LTB{sub 4}. Among the receptor tyrosine kinases including epidermal growth factor receptor (EGFR) and platelet derived growth factor receptor (PDGFR), acrolein-evoked ERK phosphorylation was attenuated by AG1478, an EGFR inhibitor, but not by AG1295, a PDGFR inhibitor. In addition, acrolein-evoked 5-LO expression was also inhibited by inhibition of EGFR pathway, but not by inhibition of PDGFR pathway. These observations suggest that acrolein has a profound effect on the 5-LO pathway via an EGFR-mediated activation of ERK pathway, leading to acute ischemic syndromes through the generation of LTB{sub 4}, subsequent MMP-9 production and plaque rupture.

  15. Synthesis, SAR, and series evolution of novel oxadiazole-containing 5-lipoxygenase activating protein inhibitors: discovery of 2-[4-(3-{(r)-1-[4-(2-amino-pyrimidin-5-yl)-phenyl]-1-cyclopropyl-ethyl}-[1,2,4]oxadiazol-5-yl)-pyrazol-1-yl]-N,N-dimethyl-acetamide (BI 665915).

    PubMed

    Takahashi, Hidenori; Riether, Doris; Bartolozzi, Alessandra; Bosanac, Todd; Berger, Valentina; Binetti, Ralph; Broadwater, John; Chen, Zhidong; Crux, Rebecca; De Lombaert, Stéphane; Dave, Rajvee; Dines, Jonathon A; Fadra-Khan, Tazmeen; Flegg, Adam; Garrigou, Michael; Hao, Ming-Hong; Huber, John; Hutzler, J Matthew; Kerr, Steven; Kotey, Adrian; Liu, Weimin; Lo, Ho Yin; Loke, Pui Leng; Mahaney, Paige E; Morwick, Tina M; Napier, Spencer; Olague, Alan; Pack, Edward; Padyana, Anil K; Thomson, David S; Tye, Heather; Wu, Lifen; Zindell, Renee M; Abeywardane, Asitha; Simpson, Thomas

    2015-02-26

    The synthesis, structure-activity relationship (SAR), and evolution of a novel series of oxadiazole-containing 5-lipoxygenase-activating protein (FLAP) inhibitors are described. The use of structure-guided drug design techniques provided compounds that demonstrated excellent FLAP binding potency (IC50 < 10 nM) and potent inhibition of LTB4 synthesis in human whole blood (IC50 < 100 nM). Optimization of binding and functional potencies, as well as physicochemical properties resulted in the identification of compound 69 (BI 665915) that demonstrated an excellent cross-species drug metabolism and pharmacokinetics (DMPK) profile and was predicted to have low human clearance. In addition, 69 was predicted to have a low risk for potential drug-drug interactions due to its cytochrome P450 3A4 profile. In a murine ex vivo whole blood study, 69 demonstrated a linear dose-exposure relationship and a dose-dependent inhibition of LTB4 production. PMID:25671290

  16. Regulation of rotenone-induced microglial activation by 5-lipoxygenase and cysteinyl leukotriene receptor 1.

    PubMed

    Zhang, Xiao-Yan; Chen, Lu; Yang, Yi; Xu, Dong-Min; Zhang, Si-Ran; Li, Chen-Tan; Zheng, Wei; Yu, Shu-Ying; Wei, Er-Qing; Zhang, Li-Hui

    2014-07-14

    The 5-lipoxygenase (5-LOX) products cysteinyl leukotrienes (CysLTs) are potent pro-inflammatory mediators. CysLTs mediate their biological actions through activating CysLT receptors (CysLT(1)R and CysLT(2)R). We have recently reported that 5-LOX and CysLT(1)R mediated PC12 cell injury induced by high concentrations of rotenone (0.3-10 μM), which was reduced by the selective 5-LOX inhibitor zileuton and CysLT(1)R antagonist montelukast. The purpose of this study was to examine the regulatory roles of the 5-LOX/CysLT(1)R pathway in microglial activation induced by low concentration rotenone. After mouse microglial BV2 cells were stimulated with rotenone (0.3-3 nM), phagocytosis and release of pro-inflammatory cytokine were assayed as indicators of microglial activation. We found that rotenone (1 and 3 nM) increased BV2 microglial phagocytosis and the release of the pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Zileuton and montelukast prevented rotenone (3 nM)-induced phagocytosis and cytokine release. Furthermore, rotenone significantly up-regulated 5-LOX expression, induced 5-LOX translocation to the nuclear envelope, and increased the production of CysLTs. These responses were inhibited by zileuton. Rotenone also increased CysLT(1)R expression and induced nuclear translocation of CysLT(1)R. In primary rat microglia, rotenone (10 nM) increased release of IL-1β and TNF-α, whereas zileuton (0.1 μΜ) and montelukast (0.01 μΜ) significantly inhibited this response. These results indicated that 5-LOX and CysLT(1)R might be key regulators of microglial activation induced by low concentration of rotenone. Interference of 5-LOX/CysLT(1)R pathway may be an effective therapeutic strategy for microglial inflammation.

  17. Integrin-dependent homotypic adhesion of neutrophils. Arachidonic acid activates Raf-1/Mek/Erk via a 5-lipoxygenase- dependent pathway.

    PubMed Central

    Capodici, C; Pillinger, M H; Han, G; Philips, M R; Weissmann, G

    1998-01-01

    AA stimulates integrin-dependent neutrophil adhesion, a critical early step in acute inflammation. However, neither the signaling pathway(s) of AA-stimulated adhesion, nor whether AA acts directly or through the generation of active metabolites, has been elucidated. Previously, we have observed a tight association between neutrophil Erk activation and homotypic adhesion in response to chemoattractants acting through G protein-linked receptors. We now report a similar association between homotypic adhesion and Erk activation in response to AA. Erk activation was cyclooxygenase independent and required AA metabolism to 5(S)- hydroperoxyeicosatetraenoic acid (5-HpETE) via 5-lipoxygenase, but not the further lipoxygenase-dependent metabolism of 5-HpETE to leukotrienes. AA stimulation of Erk was accompanied by Raf-1 activation and was sensitive to inhibitors of Raf-1 and Mek. Whereas activation of Erk by AA was pertussis toxin sensitive, [3H]-AA binding to neutrophils was not saturable, suggesting that an AA metabolite activates a G protein. Consistent with this hypothesis, Erk activation by 5(S)-hydroxyeicosatetraenoic acid (5-HETE; lipoxygenase-independent metabolite of 5-HpETE) was also pertussis toxin sensitive. These data suggest that a 5-lipoxygenase metabolite of AA, e.g., 5-HETE, is released from AA-treated cells to engage a plasma membrane-associated, pertussis toxin-sensitive, G protein-linked receptor, leading to activation of Erk and adhesion via the Raf-1/Mek signal transduction pathway. PMID:9649570

  18. Eugenol--the active principle from cloves inhibits 5-lipoxygenase activity and leukotriene-C4 in human PMNL cells.

    PubMed

    Raghavenra, H; Diwakr, B T; Lokesh, B R; Naidu, K A

    2006-01-01

    Polymorphonuclear leukocytes (PMNL) play an important role in the modulation of inflammatory conditions in humans. PMNL cells recruited at the site of inflammation, release inflammatory mediators such as leukotrienes, proteolytic enzymes and reactive oxygen species. Among these, leukotrienes are implicated in pathophysiology of allergic and inflammatory disorders like asthma, allergic rhinitis, arthritis, inflammatory bowel disease and psoriasis. 5-lipoxygenase (5-LO) is the key enzyme in biosynthetic pathway of leukotrienes. Our earlier studies showed that spice phenolic active principles significantly inhibit 5-LO enzyme in human PMNLs. In this study we have further characterized the inhibitory mechanism of eugenol, the active principle of spice-clove on 5-LO enzyme and also its effect on leukotriene C((4)) (LTC(4)). Substrate dependent enzyme kinetics showed that the inhibitory effect of eugenol on 5-LO was of a non-competitive nature. Further, eugenol was found to significantly inhibit the formation of LTC(4) in calcium ionophore A23187 and arachidonic acid (AA) stimulated PMNL cells. These data clearly suggest that eugenol inhibits 5-LO by non-competitive mechanism and also inhibits formation of LTC(4) in human PMNL cells and thus may have beneficial role in modulating 5-LO pathway in human PMNL cells. PMID:16216483

  19. Eugenol--the active principle from cloves inhibits 5-lipoxygenase activity and leukotriene-C4 in human PMNL cells.

    PubMed

    Raghavenra, H; Diwakr, B T; Lokesh, B R; Naidu, K A

    2006-01-01

    Polymorphonuclear leukocytes (PMNL) play an important role in the modulation of inflammatory conditions in humans. PMNL cells recruited at the site of inflammation, release inflammatory mediators such as leukotrienes, proteolytic enzymes and reactive oxygen species. Among these, leukotrienes are implicated in pathophysiology of allergic and inflammatory disorders like asthma, allergic rhinitis, arthritis, inflammatory bowel disease and psoriasis. 5-lipoxygenase (5-LO) is the key enzyme in biosynthetic pathway of leukotrienes. Our earlier studies showed that spice phenolic active principles significantly inhibit 5-LO enzyme in human PMNLs. In this study we have further characterized the inhibitory mechanism of eugenol, the active principle of spice-clove on 5-LO enzyme and also its effect on leukotriene C((4)) (LTC(4)). Substrate dependent enzyme kinetics showed that the inhibitory effect of eugenol on 5-LO was of a non-competitive nature. Further, eugenol was found to significantly inhibit the formation of LTC(4) in calcium ionophore A23187 and arachidonic acid (AA) stimulated PMNL cells. These data clearly suggest that eugenol inhibits 5-LO by non-competitive mechanism and also inhibits formation of LTC(4) in human PMNL cells and thus may have beneficial role in modulating 5-LO pathway in human PMNL cells.

  20. Discovery of a novel activator of 5-lipoxygenase from an anacardic acid derived compound collection

    PubMed Central

    Wisastra, Rosalina; Kok, Petra A.M; Eleftheriadis, Nikolaos; Baumgartner, Matthew P.; Camacho, Carlos J.; Haisma, Hidde J.; Dekker, Frank J.

    2013-01-01

    Lipoxygenases (LOXs) and cyclooxygenases (COXs) metabolize poly-unsaturated fatty acids into inflammatory signaling molecules. Modulation of the activity of these enzymes may provide new approaches for therapy of inflammatory diseases. In this study, we screened novel anacardic acid derivatives as modulators of human 5-LOX and COX-2 activity. Interestingly, a novel salicylate derivative 23a was identified as a surprisingly potent activator of human 5-LOX. This compound showed both non-competitive activation towards the human 5-LOX activator adenosine triphosphate (ATP) and non-essential mixed type activation against the substrate linoleic acid, while having no effect on the conversion of the substrate arachidonic acid. The kinetic analysis demonstrated a non-essential activation of the linoleic acid conversion with a KA of 8.65 μM, αKA of 0.38 μM and a β value of 1.76. It is also of interest that a comparable derivative 23d showed a mixed type inhibition for linoleic acid conversion. These observations indicate the presence of an allosteric binding site in human 5-LOX distinct from the ATP binding site. The activatory and inhibitory behavior of 23a and 23d on the conversion of linoleic compared to arachidonic acid are rationalized by docking studies, which suggest that the activator 23a stabilizes linoleic acid, whereas the larger inhibitor 23d blocks the enzyme active site. PMID:24231650

  1. Active site characterization and structure based 3D-QSAR studies on non-redox type 5-lipoxygenase inhibitors.

    PubMed

    Ul-Haq, Zaheer; Khan, Naveed; Zafar, Syed Kashif; Moin, Syed Tarique

    2016-06-10

    Structure-based 3D-QSAR study was performed on a class of 5-benzylidene-2-phenylthiazolinones non-redox type 5-LOX inhibitors. In this study, binding pocket of 5-Lipoxygenase (pdb id 3o8y) was identified by manual docking using 15-LOX (pdb id 2p0m) as a reference structure. Additionally, most of the binding site residues were found conserved in both structures. These non-redox inhibitors were then docked into the binding site of 5-LOX. To generate reliable CoMFA and CoMSIA models, atom fit data base alignment method using docked conformation of the most active compound was employed. The q(2)cv and r(2)ncv values for CoMFA model were found to be 0.549 and 0.702, respectively. The q(2)cv and r(2)ncv values for the selected CoMSIA model comprised four descriptors steric, electrostatic, hydrophobic and hydrogen bond donor fields were found to be 0.535 and 0.951, respectively. Obtained results showed that our generated model was statistically reliable. Furthermore, an external test set validates the reliability of the predicted model by calculating r(2)pred i.e.0.787 and 0.571 for CoMFA and CoMSIA model, respectively. 3D contour maps generated from CoMFA and CoMSIA models were utilized to determine the key structural features of ligands responsible for biological activities. The applied protocol will be helpful to design more potent and selective inhibitors of 5-LOX. PMID:27044904

  2. Ethanol Promotes Chemically Induced Oral Cancer in Mice through Activation of the 5-Lipoxygenase Pathway of Arachidonic Acid Metabolism

    PubMed Central

    Guo, Yizhu; Wang, Xin; Zhang, Xinyan; Sun, Zheng; Chen, Xiaoxin

    2011-01-01

    Alcohol drinking is a known risk factor for oral cancer in humans. However, previous animal studies on the promoting effect of ethanol on oral carcinogenesis were inconclusive. It is necessary to develop an animal model with which the molecular mechanism of ethanol-related oral carcinogenesis may be elucidated in order to develop effective prevention strategies. In this study, mice were first treated with 4-nitroquinoline-1-oxide (4NQO, 100μg/ml in drinking water) for 8 weeks, and then given water or ethanol (8%) as the sole drink for another 16 weeks. During the experiment, 8% ethanol was well tolerated by mice. The incidence of squamous cell carcinoma (SCC) increased from 20% (8/41) to 43% (17/40; p<0.05). Expression of 5-lipoxygenase (5-Lox) and cyclooxygenase 2 (Cox-2) was increased in dysplasia and SCC of 4NQO-treated tongues, and further enhanced by ethanol. Using this mouse model, we further demonstrated that fewer cancers were induced in Alox5−/− mice, as were cell proliferation, inflammation, and angiogenesis in the tongue, as compared with Alox5+/+ mice. Interestingly, Cox-2 expression was induced by ethanol in knockout mice, while 5-Lox and leukotriene A4 hydrolase (LTA4H) expression and leukotriene B4 (LTB4) biosynthesis were dramatically reduced. Moreover, ethanol enhanced expression and nuclear localization of 5-Lox and stimulated LTB4 biosynthesis in human tongue SCC cells (SCC-15 and SCC-4) in vitro. In conclusion, this study clearly demonstrated that ethanol promoted 4NQO-induced oral carcinogenesis, at least in part, through further activation of the 5-Lox pathway of arachidonic acid metabolism. PMID:21881027

  3. Sulphatides trigger polymorphonuclear granulocyte spreading on collagen-coated surfaces and inhibit subsequent activation of 5-lipoxygenase.

    PubMed Central

    Sud'ina, G F; Brock, T G; Pushkareva, M A; Galkina, S I; Turutin, D V; Peters-Golden, M; Ullrich, V

    2001-01-01

    Sulphatides are sulphate esters of galactocerebrosides that are present on the surfaces of many cell types and act as specific ligands to selectins. The present study was undertaken to investigate the effect of sulphatides on polymorphonuclear granulocyte (PMN) attachment, spreading and 5-lipoxygenase (5-LO) metabolism. Sulphatides, but not non-sulphated galactocerebrosides, dose-dependently enhanced attachment to collagen, as measured by the myeloperoxidase assay. Studies with blocking antibodies indicated that the increased attachment was mediated by CD11b/CD18 (Mac-1) beta 2 integrin. Scanning electron microscopy indicated that sulphatides also greatly enhanced the degree of cell spreading. In PMNs treated in suspension, sulphatides had no effect on the ionophore A23187-stimulated release of arachidonic acid and the synthesis of 5-LO metabolites. In contrast, in PMNs attached to collagen, the enzymic conversion of arachidonic acid by 5-LO was inhibited by sulphatides. Inhibition of 5-LO metabolism by sulphatides was observed even in the presence of exogenous substrate, suggesting that sulphatides directly inhibited 5-LO action. Consistent with this, sulphatides interfered with ionophore-induced translocation of the 5-LO to the nuclear envelope. Substances competing with sulphatide binding to cells, like dextran sulphate, or a strong inhibitor of cell spreading, like the actin-polymerizing agent jasplakinolide, prevented the effects of sulphatides on PMN attachment and spreading and leukotriene synthesis. We conclude that shape changes occurring in response to sulphatides specifically impair PMN leukotriene synthesis by inhibiting translocation of 5-LO. PMID:11672437

  4. Suppression of oxidative stress and 5-lipoxygenase activation by edaravone improves depressive-like behavior after concussion.

    PubMed

    Higashi, Youichirou; Hoshijima, Michihiro; Yawata, Toshio; Nobumoto, Atsuya; Tsuda, Masayuki; Shimizu, Takahiro; Saito, Motoaki; Ueba, Tetuya

    2014-10-15

    Brain concussions are a serious public concern and are associated with neuropsychiatric disorders, such as depression. Patients with concussion who suffer from depression often experience distress. Nevertheless, few pre-clinical studies have examined concussion-induced depression, and there is little information regarding its pharmacological management. Edaravone, a free radical scavenger, can exert neuroprotective effects in several animal models of neurological disorders. However, the effectiveness of edaravone in animal models of concussion-induced depression remains unclear. In this study, we examined whether edaravone could prevent concussion-induced depression. Mice were subjected to a weight-drop injury and intravenously administered edaravone (3.0 mg/kg) or vehicle immediately after impact. Serial magnetic resonance imaging showed no abnormalities of the cerebrum on diffusion T1- and T2-weighted images. We found that edaravone suppressed concussion-induced depressive-like behavior in the forced swim test, which was accompanied by inhibition of increased hippocampal and cortical oxidative stress (OS) and suppression of 5-lipoxygenase (5-LOX) translocation to the nuclear envelope in hippocampal astrocytes. Hippocampal OS in concussed mice was also prevented by the nicotinamide adenine dinucleotide phosphate oxidase inhibitor, apocynin, and administration of BWB70C, a 5-LOX inhibitor, immediately and 24 h after injury prevented depressive-like behaviors in concussed mice. Further, antidepressant effects of edaravone were observed in mice receiving 1.0 or 3.0 mg/kg of edaravone immediately after impact, but not at a lower dose of 0.1 mg/kg. This antidepressant effect persisted up to 1 h after impact, whereas edaravone treatment at 3 h after impact had no effect on concussion-induced depressive-like behavior. These results suggest that edaravone protects against concussion-induced depression, and this protection is mediated by suppression of OS and 5

  5. Stress-induced nuclear export of 5-lipoxygenase

    SciTech Connect

    Hanaka, Hiromi; Shimizu, Takao; Izumi, Takashi . E-mail: takizumi@med.gunma-u.ac.jp

    2005-12-09

    A key enzyme for leukotriene biosynthesis is 5-lipoxygenase (5-LO), which we found is exported from the nucleus when p38 MAPK is activated. CHO-K1 cells stably express green fluorescent protein-5-lipoxygenase fusion protein (GFP-5LO), which is located predominantly in the nucleus, and is exported by anisomycin, hydrogen peroxide, and sorbitol, with activation of p38 MAPK. SB203580, an inhibitor of p38 MAPK, and Leptomycin B, an inhibitor of the nuclear export, blocked the anisomycin-induced export of GFP-5LO. When HEK293 cells were transformed with plasmids for wild-type GFP-5LO, GFP-5LO-S271A or GFP-5LO-S271E mutants, most wild-type GFP-5LO and GFP-5LO-S271A localized in the nucleus, but GFP-5LO-S271E localized in the cytosol. Thus, phosphorylation at Ser-271 of 5-LO is important for its export. Endogenous 5-LO in RBL cells stimulated with anisomycin was also exported from the nucleus. These results suggest that the nuclear export of 5-LO depends on the stress-induced activation of the p38 MAPK pathway.

  6. 4-Hydroxynonenal enhances MMP-9 production in murine macrophages via 5-lipoxygenase-mediated activation of ERK and p38 MAPK

    SciTech Connect

    Lee, Seung J.; Kim, Chae E.; Yun, Mi R.; Seo, Kyo W.; Park, Hye M.; Yun, Jung W.; Shin, Hwa K.; Bae, Sun S.; Kim, Chi D.

    2010-01-15

    Exaggerated levels of 4-hydroxynonenal (HNE) and 5-lipoxygenase (5-LO) co-exist in macrophages in atherosclerotic lesions, and activated macrophages produce MMP-9 that degrades atherosclerotic plaque constituents. This study investigated the effects of HNE on MMP-9 production, and the potential role for 5-LO derivatives in MMP-9 production in murine macrophages. Stimulation of J774A.1 cells with HNE led to activation of 5-LO, as measured by leukotriene B{sub 4} (LTB{sub 4}) production. This was associated with an increased production of MMP-9, which was blunted by inhibition of 5-LO with MK886, a 5-LO inhibitor or with 5-LO siRNA. A cysteinyl-LT{sub 1} (cysLT{sub 1}) receptor antagonist, REV-5901 as well as a BLT{sub 1} receptor antagonist, U-75302, also attenuated MMP-9 production induced by HNE. Furthermore, LTB{sub 4} and cysLT (LTC{sub 4} and LTD{sub 4}) enhanced MMP-9 production in macrophages, suggesting a pivotal role for 5-LO in HNE-mediated production of MMP-9. Among the MAPK pathways, LTB{sub 4} and cysLT enhanced phosphorylation of ERK and p38 MAPK, but not JNK. Linked to these results, a p38 MAPK inhibitor as well as an ERK inhibitor blunted MMP-9 production induced by LT. Collectively, these data suggest that 5-LO-derived LT mediates HNE-induced MMP-9 production via activation of ERK and p38 MAPK pathways, consequently leading to plaque instability in atherosclerosis.

  7. Molecular cloning and amino acid sequence of human 5-lipoxygenase

    SciTech Connect

    Matsumoto, T.; Funk, C.D.; Radmark, O.; Hoeoeg, J.O.; Joernvall, H.; Samuelsson, B.

    1988-01-01

    5-Lipoxygenase (EC 1.13.11.34), a Ca/sup 2 +/- and ATP-requiring enzyme, catalyzes the first two steps in the biosynthesis of the peptidoleukotrienes and the chemotactic factor leukotriene B/sub 4/. A cDNA clone corresponding to 5-lipoxygenase was isolated from a human lung lambda gt11 expression library by immunoscreening with a polyclonal antibody. Additional clones from a human placenta lambda gt11 cDNA library were obtained by plaque hybridization with the /sup 32/P-labeled lung cDNA clone. Sequence data obtained from several overlapping clones indicate that the composite DNAs contain the complete coding region for the enzyme. From the deduced primary structure, 5-lipoxygenase encodes a 673 amino acid protein with a calculated molecular weight of 77,839. Direct analysis of the native protein and its proteolytic fragments confirmed the deduced composition, the amino-terminal amino acid sequence, and the structure of many internal segments. 5-Lipoxygenase has no apparent sequence homology with leukotriene A/sub 4/ hydrolase or Ca/sup 2 +/-binding proteins. RNA blot analysis indicated substantial amounts of an mRNA species of approx. = 2700 nucleotides in leukocytes, lung, and placenta.

  8. Substituted (pyridylmethoxy)naphthalenes as potent and orally active 5-lipoxygenase inhibitors; synthesis, biological profile, and pharmacokinetics of L-739,010.

    PubMed

    Hamel, P; Riendeau, D; Brideau, C; Chan, C C; Desmarais, S; Delorme, D; Dubé, D; Ducharme, Y; Ethier, D; Grimm, E; Falgueyret, J P; Guay, J; Jones, T R; Kwong, E; McAuliffe, M; McFarlane, C S; Piechuta, H; Roumi, M; Tagari, P; Young, R N; Girard, Y

    1997-08-29

    Dioxabicyclooctanyl naphthalenenitriles have been reported as a class of potent and nonredox 5-lipoxygenase (5-LO) inhibitors. These bicyclo derivatives were shown to be metabolically more stable than their tetrahydropyranyl counterparts but were not well orally absorbed. Replacement of the phenyl ring in the naphthalenenitrile 1 by a pyridine ring leads to the potent and orally absorbed inhibitor 3g (L-739,010, 2-cyano-4-(3-furyl)-7-[[6-[3-(3-hydroxy-6,8-dioxabicyclo[3.2.1] octanyl)]-2-pyridyl]methoxy]naphthalene). Compound 3g inhibits 5-HPETE production by human 5-LO and LTB4 biosynthesis by human PMN leukocytes and human whole blood (IC50S of 20, 1.6, and 42 nM, respectively). Derivative 3g is orally active in the rat pleurisy model (inhibition of LTB4, ED50 = 0.3 mg/kg) and in the anesthetized dog model (inhibition of ex vivo whole blood LTB4 and urinary LTE4, ED50 = 0.45 and 0.23 microgram/kg/min, respectively, i.v. infusion). In addition, 3g shows excellent functional activity against ovalbumin-induced dyspnea in rats (60% inhibition at 0.5 mg/kg, 4 h pretreatment) and Ascaris-induced bronchoconstriction in conscious sheep (50% and > 85% inhibition in early and late phases, respectively at 2.5 micrograms/kg/min, i.v. infusion) and, more particularly in the conscious antigen sensitive squirrel monkey model (53% inhibition of the increase in RL and 76% in the decrease of Cdyn, at 0.1 mg/kg, po). In rats and dogs, 3g presents excellent pharmacokinetics (estimated half-lives of 5 and 16 h, respectively) and bioavailabilities (26% and 73% when dosed as its hydrochloride salt at doses of 20 and 10 mg/kg, respectively, in methocel suspension). Based on its overall biological profile, compound 3g has been selected for preclinical animal toxicity studies.

  9. Effects of exogenous arachidonic, eicosapentaenoic, and docosahexaenoic acids on the generation of 5-lipoxygenase pathway products by ionophore-activated human neutrophils.

    PubMed Central

    Lee, T H; Mencia-Huerta, J M; Shih, C; Corey, E J; Lewis, R A; Austen, K F

    1984-01-01

    Exogenous eicosapentaenoic acid (EPA) and docosahexaenoic acid (DCHA) have been compared with exogenous arachidonic acid for their capacity to modulate the oxidative metabolism of membrane-derived arachidonic acid by the 5-lipoxygenase pathway in ionophore-activated human neutrophils and for their suitability as parallel substrates in this pathway. The products from specific 14C- or 3H-labeled substrates were isolated by reverse phase high performance liquid chromatography (RP-HPLC) and were identified by elution of radiolabel at the retention times of the appropriate synthetic standards. Each product was also characterized by its ultraviolet (UV) absorption spectrum, and 7-hydroxy-DCHA was defined in addition by analysis of its mass spectrum. The metabolites, 5-hydroxyeicosatetraenoic acid, leukotriene B4 (LTB4), 6-trans-LTB4 diastereoisomers, 5-hydroxyeicosapentaenoic acid, 6-trans-leukotriene B5 diastereoisomers, leukotriene B5 (LTB5), and 7-hydroxy-DCHA were quantitated by integrated UV absorbance during resolution by RP-HPLC. LTB4 and LTB5 were also quantitated by radioimmunoassay of the eluate fractions, and leukotrienes C4 and C5 (LTC4 and LTC5, respectively) were quantitated by radioimmunoassay alone. None of the unlabeled exogenous fatty acids (5-40 micrograms/ml) altered the release of radioactivity from [14C]arachidonic acid-labeled, ionophore-activated neutrophils. The metabolism of 5 and 10 micrograms/ml of exogenous EPA by ionophore-activated, [14C]arachidonic acid-labeled neutrophils not only generated 5-hydroxyeicosapentaenoic acid, 6-trans-LTB5, LTB5, and LTC5, but also stimulated the formation of 5-hydroxyeicosatetraenoic acid, 6-trans-LTB4 diastereoisomers, and LTC4 from membrane-derived arachidonic acid. In contrast, LTB4 production was diminished throughout the EPA dose-response, beginning at 5 micrograms/ml EPA and reaching 50% suppression at 10 micrograms/ml and 84% suppression at 40 micrograms/ml. The selective decrease in extracellular LTB4

  10. Inhibition of 5-lipoxygenase by vitamin E.

    PubMed

    Reddanna, P; Rao, M K; Reddy, C C

    1985-11-25

    Purified 5-lipoxygenase from potato tubers was inhibited strongly by vitamin E and its analogs. The inhibition by d-alpha-tocopherol was found to be irreversible and non-competitive with respect to arachidonic acid. An IC50 of 5 microM was calculated for d-alpha-tocopherol. The inhibition appears to be unrelated to its antioxidant function. Binding studies with 14C-labelled d-alpha-tocopherol revealed that there is a strong interaction between vitamin E and 5-lipoxygenase. Tryptic digestion and peptide mapping of 5-lipoxygenase-vitamin E complex indicate that vitamin E binds strongly to a single peptide. These studies suggest that cellular vitamin E levels may have profound influence on the formation of leukotrienes. PMID:3934003

  11. Exogenous action of 5-lipoxygenase by its metabolites on luteinizing hormone release in rat pituitary cells.

    PubMed

    Przylipiak, A; Kiesel, L; Habenicht, A J; Przylipiak, M; Runnebaum, B

    1990-02-12

    The stimulatory effect of exogenously administered potato 5-lipoxygenase (0.1-0.3 U/2 ml) on luteinizing hormone (LH) release was demonstrated in rat anterior pituitary cells in a superfusion system. Nordihydroguaiaretic acid (NDGA), an inhibitor of 5-lipoxygenase, abolished the effect of the enzyme on LH secretion. The secretory effect on LH after 5-lipoxygenase administration was biphasic and dependent on Ca2+ indicating that 5-lipoxygenase affects LH release through its oxygenation reaction. Another series of experiments demonstrated that activation of 5-lipoxygenase, expressed as production of leukotriene (LT) B4 and C4 (728 +/- 127 pg/10(6) cells and 178 +/- 23 pg/10(6) cells, respectively) occurs in rat pituitary cells after addition of Ca2+ ionophore A23187. However, LTB4 and LTC4 were not formed by pituitary cells that had previously been desensitized by gonadotropin-releasing hormone (GnRH), the physiological ligand of LH release. These results are consistent with a role of 5-lipoxygenase metabolites in the mechanism of GnRH-induced LH secretion. PMID:2157615

  12. Expression of 5-lipoxygenase (5-LOX) in T lymphocytes

    PubMed Central

    Cook-Moreau, Jeanne M; El-Makhour Hojeij, Yola; Barrière, Guislaine; Rabinovitch-Chable, Hélène C; Faucher, Karine S; Sturtz, Franck G; Rigaud, Michel A

    2007-01-01

    5-lipoxygenase (5-LOX) is the key enzyme responsible for the synthesis of the biologically active leukotrienes. Its presence has been reported in cells of the myeloid lineage and B lymphocytes but has not been formally defined in T lymphocytes. In this study, we provide evidence for 5-LOX expression on both transcriptional and translational levels in highly purified peripheral blood T cells as well as in human T lymphoblastoid cell lines (MOLT4 and Jurkat). Messenger RNA (mRNA) of 5-LOX was amplified by conventional reverse transcription–polymerase chain reaction (RT-PCR; MOLT4 and Jurkat cells) and by in situ RT-PCR (T lymphocytes). 5-LOX protein expression was confirmed by Western blot and immunofluorescence studies. 5-LOX was present primarily in the cytoplasm with some nuclear localization and was translocated to the nuclear periphery after culture in a mitosis-supporting medium. Fluorescence-activated cell sorter analysis of different T-lymphocyte populations, including CD4, CD8, CD45RO, CD45RA, T helper type 2, and T-cell receptor-αβ and -γδ expressing cells, did not identify a differential distribution of the enzyme. Purified peripheral blood T lymphocytes were incapable of synthesizing leukotrienes in the absence of exogenous arachidonic acid. Jurkat cells produced leukotriene C4 and a small amount of leukotriene B4 in response to CD3–CD28 cross-linking. This synthesis was abolished by two inhibitors of leukotriene synthesis, MK-886 and AA-861. The presence of 5-LOX in T lymphocytes but the absence of endogenous lipoxygenase metabolite production compared to Jurkat cells may constitute a fundamental difference between resting peripheral lymphocytes and leukaemic cells. PMID:17484769

  13. Synthesis and biological evaluation of salicylic acid and N-acetyl-2-carboxybenzenesulfonamide regioisomers possessing a N-difluoromethyl-1,2-dihydropyrid-2-one pharmacophore: dual inhibitors of cyclooxygenases and 5-lipoxygenase with anti-inflammatory activity.

    PubMed

    Chowdhury, Morshed A; Abdellatif, Khaled R A; Dong, Ying; Das, Dipankar; Yu, Gang; Velázquez, Carlos A; Suresh, Mavanur R; Knaus, Edward E

    2009-12-15

    A novel class of salicylic acid and N-acetyl-2-carboxybenzenesulfonamide regioisomers possessing a N-difluoromethyl-1,2-dihydropyrid-2-one pharmacophore attached to its C-4 or C-5 position was designed for evaluation as anti-inflammatory (AI) agents. Replacement of the 2,4-difluorophenyl ring in diflunisal by the N-difluoromethyl-1,2-dihydropyrid-2-one moiety provided compounds showing dual selective cyclooxygenase-2 (COX-2)/5-lipoxygenase (5-LOX) inhibitory activities. AI structure-activity studies showed that the C-4 (14a) and C-5 (14b) salicylate regioisomers were 1.4- and 1.6-fold more potent than aspirin, and the C-5 N-acetyl-2-carboxybenzenesulfonamide regioisomer (22b) was 1.3- and 2.8-fold more potent than ibuprofen and aspirin, respectively. In vivo ulcer index (UI) studies showed that the 4- and 5-(N-difluoromethyl-1,2-dihydropyrid-2-one-4-yl)salicylic acids (14a and 14b) were completely non-ulcerogenic since no gastric lesions were present (UI=0) relative to aspirin (UI=57) at an equivalent mumol/kg oral dose. The N-difluoromethyl-1,2-dihydropyridin-2-one moiety provides a novel 5-LOX pharmacophore for the design of cyclic hydroxamic mimetics for exploitation in the development of dual COX-2/5-LOX inhibitory AI drugs.

  14. 5-Lipoxygenase facilitates healing after myocardial infarction.

    PubMed

    Blömer, Nadja; Pachel, Christina; Hofmann, Ulrich; Nordbeck, Peter; Bauer, Wolfgang; Mathes, Denise; Frey, Anna; Bayer, Barbara; Vogel, Benjamin; Ertl, Georg; Bauersachs, Johann; Frantz, Stefan

    2013-07-01

    Early healing after myocardial infarction (MI) is characterized by a strong inflammatory reaction. Most leukotrienes are pro-inflammatory and are therefore potential mediators of healing and remodeling after myocardial ischemia. The enzyme 5-lipoxygenase (5-LOX) has a key role in the transformation of arachidonic acid in leukotrienes. Thus, we tested the effect of 5-LOX on healing after MI. After chronic coronary artery ligation, early mortality was significantly increased in 5-LOX(-/-) when compared to matching wildtype (WT) mice due to left ventricular rupture. This effect could be reproduced in mice treated with the 5-LOX inhibitor Zileuton. A perfusion mismatch due to the vasoactive potential of leukotrienes is not responsible for left ventricular rupture since local blood flow assessed by magnetic resonance perfusion measurements was not different. However, after MI, there was an accentuation of the inflammatory reaction with an increase of pro-inflammatory macrophages. Yet, mortality was not changed in chimeric mice (WT vs. 5-LOX(-/-) bone marrow in 5-LOX(-/-) animals), indicating that an altered function of 5-LOX(-/-) inflammatory cells is not responsible for the phenotype. Collagen production and accumulation of fibroblasts were significantly reduced in 5-LOX(-/-) mice in vivo after MI. This might be due to an impaired migration of 5-LOX(-/-) fibroblasts, as shown in vitro to serum. In conclusion, a lack or inhibition of 5-LOX increases mortality after MI because of healing defects. This is not mediated by a change in local blood flow, but through an altered inflammation and/or fibroblast function.

  15. Tepoxalin: a dual cyclooxygenase/5-lipoxygenase inhibitor of arachidonic acid metabolism with potent anti-inflammatory activity and a favorable gastrointestinal profile.

    PubMed

    Argentieri, D C; Ritchie, D M; Ferro, M P; Kirchner, T; Wachter, M P; Anderson, D W; Rosenthale, M E; Capetola, R J

    1994-12-01

    Tepoxalin [5-(4-chlorophenyl)-N-hydroxy-(4-methoxyphenyl)-N-methyl-1H- pyrazole-3-propanamide] is a potent inhibitor of sheep seminal vesicle cyclooxygenase (CO) (IC50 = 4.6 microM), rat basophilic leukemia cell (RBL-1) lysate CO (IC50 = 2.85 microM) and CO from intact RBL-1 cells (IC50 = 4.2 microM). The compound inhibits the production of thromboxane B2 (TxB2) in Ca++ ionophore A-23187-stimulated human peripheral blood leukocytes (HPBL; IC50 = 0.01 microM) and human whole blood (IC50 = 0.08 microM) and is a potent inhibitor of epinephrine-induced human platelet aggregation (IC50 = 0.045 microM). Tepoxalin inhibits lipoxygenase (LO) in RBL-1 lysates (IC50 = 0.15 microM) and intact RBL-1 cells (IC50 = 1.7 microM) and inhibits the generation of leukotriene B4 (LTB4) in calcium ionophore A-23187-stimulated HPBL (IC50 = 0.07 microM) and human whole blood (IC50 = 1.57 microM). Human platelet 12-LO (IC50 = 3.0 microM) is inhibited, but 15-LO is only weakly so (IC50 = 157 microM). In vivo, tepoxalin, administered orally, demonstrated potent anti-inflammatory activity in the established adjuvant arthritic rat (ED50 = 3.5 mg/kg) and potent analgesic activity in the acetic acid abdominal construction assay in mice (ED50 = 0.45 mg/kg). In an ex vivo whole blood eicosanoid production assay, tepoxalin produces a dose-related inhibition of prostaglandin (PG) and LT production in dogs (PGF2 alpha - ED50 = 0.015 mg/kg; LTB4 - ED50 = 2.37 mg/kg) and adjuvant arthritic rats following oral administration. In adjuvant arthritic rats, tepoxalin is devoid of ulcerogenic activity within its anti-inflammatory therapeutic range (1-33 mg/kg p.o.) and does not exhibit ulcerogenic activity in normal rats at doses lower than 100 mg/kg (UD50 = 173 mg/kg p.o.). Tepoxalin represents a new class of anti-inflammatory drugs which may exhibit less gastrointestinal toxicity and may be efficacious in immunoinflammatory disease states where excessive PG and LT production has been implicated and may

  16. 5-Lipoxygenase Inhibitors Attenuate TNF-α-Induced Inflammation in Human Synovial Fibroblasts

    PubMed Central

    Lin, Han-Ching; Lin, Tzu-Hung; Wu, Ming-Yueh; Chiu, Yung-Cheng; Tang, Chih-Hsin; Hour, Mann-Jen; Liou, Houng-Chi; Tu, Huang-Ju; Yang, Rong-Sen; Fu, Wen-Mei

    2014-01-01

    The lipoxygenase isoform of 5-lipoxygenase (5-LOX) is reported to be overexpressed in human rheumatoid arthritis synovial tissue and involved in the progress of inflammatory arthritis. However, the detailed mechanism of how 5-lipoxygenase regulates the inflammatory response in arthritis synovial tissue is still unclear. The aim of this study was to investigate the involvement of lipoxygenase pathways in TNF-α-induced production of cytokines and chemokines. Human synovial fibroblasts from rheumatoid patients were used in this study. 5-LOX inhibitors and shRNA were used to examine the involvement of 5-LOX in TNF-α-induced cytokines and chemokines expression. The signaling pathways were examined by Western Blotting or immunofluorescence staining. The effect of 5-LOX inhibitor on TNF-α-induced chemokine expression and paw edema was also explored in vivo in C57BL/6 mice. Treatment with 5-LOX inhibitors significantly decreased TNF-α-induced pro-inflammatory mediators including interleukin-6 (IL-6) and monocyte chemo-attractant protein-1 (MCP-1) in human synovial fibroblasts. Knockdown of 5-LOX using shRNA exerted similar inhibitory effects. The abrogation of NF-κB activation was involved in the antagonizing effects of these inhibitors. Furthermore, 5-LOX inhibitor decreased TNF-α-induced up-regulation of serum MCP-1 level and paw edema in mouse model. Our results provide the evidence that the administration of 5-LOX inhibitors is able to ameliorate TNF-α-induced cytokine/chemokine release and paw edema, indicating that 5-LOX inhibitors may be developed for therapeutic treatment of inflammatory arthritis. PMID:25229347

  17. Identification of the substrate access portal of 5-Lipoxygenase

    PubMed Central

    Mitra, Sunayana; Bartlett, Sue G.

    2016-01-01

    The overproduction of inflammatory lipid mediators derived from arachidonic acid contributes to asthma and cardiovascular diseases, among other pathologies. Consequently, the enzyme that initiates the synthesis of pro-inflammatory leukotrienes, 5-lipoxygenase (5-LOX), is a target for drug design. The crystal structure of 5-LOX revealed a fully encapsulated active site, thus the point of substrate entry is not known. We asked whether a structural motif, a “cork” present in 5-LOX but absent in other mammalian lipoxygenases, might be ejected to allow substrate access. Our results indicate that reduction of cork volume facilitates access to the active site. However, if cork entry into the site is obstructed, enzyme activity is significantly compromised. The results support a model in which the “cork” that shields the active site in the absence of substrate serves as the active site portal, but the “corking” amino acid Phe-177 plays a critical role in providing a fully functional active site. Thus the more appropriate metaphor for this structural motif is a “twist-and-pour” cap. Additional mutagenesis data are consistent with a role for His-600, deep in the elongated cavity, in positioning the substrate for catalysis. PMID:26427761

  18. The 5-lipoxygenase pathway: oxidative and inflammatory contributions to the Alzheimer’s disease phenotype

    PubMed Central

    Joshi, Yash B.; Praticò, Domenico

    2015-01-01

    Alzheimer’s disease (AD) is the most common, and, arguably, one of the most-well studied, neurodegenerative conditions. Several decades of investigation have revealed that amyloid-β and tau proteins are critical pathological players in this condition. Genetic analyses have revealed specific mutations in the cellular machinery that produces amyloid-β, but these mutations are found in only a small fraction of patients with the early-onset variant of AD. In addition to development of amyloid-β and tau pathology, oxidative damage and inflammation are consistently found in the brains of these patients. The 5-lipoxygenase protein enzyme (5LO) and its downstream leukotriene metabolites have long been known to be important modulators of oxidation and inflammation in other disease states. Recent in vivo evidence using murine knock-out models has implicated the 5LO pathway, which also requires the 5LO activating protein (FLAP), in the molecular pathology of AD, including the metabolism of amyloid-β and tau. In this manuscript, we will provide an overview of 5LO and FLAP, discussing their involvement in biochemical pathways relevant to AD pathogenesis. We will also discuss how the 5LO pathway contributes to the molecular and behavioral insults seen in AD and provide an assessment of how targeting these proteins could lead to therapeutics relevant not only for AD, but also other related neurodegenerative conditions. PMID:25642165

  19. A new 5-lipoxygenase selective inhibitor derived from Artocarpus communis strongly inhibits arachidonic acid-induced ear edema.

    PubMed

    Koshihara, Y; Fujimoto, Y; Inoue, H

    1988-06-01

    Natural compounds isolated from the Indonesian plant, Artocarpus communis, inhibit 5-lipoxygenase of cultured mastocytoma cells. One of five compounds, AC-5-1, strongly inhibits 5-lipoxygenase with a half-inhibition dose of 5 +/- 0.12 X 10(-8) M. However, prostaglandin synthesizing activity is not inhibited until 10(-5) M. AC-5-1 is a highly selective inhibitor for 5-lipoxygenase. The AC-5-1 at 10(-5) M inhibits 96% of leukotriene C4 synthesis of mouse peritoneal cells facilitated by calcium-ionophore. Arachidonic acid-induced ear edema of mice, an in vivo inflammatory model, involving leukotriene induction, is strongly inhibited by AC-5-1 in a dose-dependent manner. The inhibition is the strongest of any inhibitors of 5-lipoxygenase reported previously. Since the natural compound AC-5-1 can selectively inhibit 5-lipoxygenase and affect in vivo inflammation, it will be interesting to investigate the role of leukotrienes on inflammation and other physiological processes.

  20. Arachidonate 5 Lipoxygenase Expression in Papillary Thyroid Carcinoma Promotes Invasion via MMP-9 Induction

    PubMed Central

    Kummer, Nicolas T.; Nowicki, Theodore S; Azzi, Jean Paul; Reyes, Ismael; Iacob, Codrin; Xie, Suqing; Swati, Ismatun; Suslina, Nina; Schantz, Stimson; Tiwari, Raj K.; Geliebter, Jan

    2012-01-01

    Arachidonate 5-lipoxygenase (ALOX5) expression and activity has been implicated in tumor pathogenesis, yet its role in papillary thyroid carcinoma (PTC) has not been characterized. ALOX5 protein and mRNA were upregulated in PTC compared to matched, normal thyroid tissue, and ALOX5 expression correlated with invasive tumor histopathology. Evidence suggests that PTC invasion is mediated through the induction of matrix metalloproteinases (MMPs) that can degrade and remodel the extracellular matrix (ECM). A correlation between MMP-9 and ALOX5 protein expression was established by immunohistochemical analysis of PTC and normal thyroid tissues using a tissue array. Transfection of ALOX5 into a PTC cell line (BCPAP) increased MMP-9 secretion and cell invasion across an ECM barrier. The ALOX5 product, 5(S)-hydroxyeicosatetraenoic acid also increased MMP-9 protein expression by BCPAP in a dose-dependent manner. Inhibitors of MMP-9 and ALOX5 reversed ALOX5-enhanced invasion. Here we describe a new role for ALOX5 as a mediator of invasion via MMP-9 induction; this ALOX5/MMP9 pathway represents a new avenue in the search for functional biomarkers and/or potential therapeutic targets for aggressive PTC. PMID:22253131

  1. Kinetic investigation of human 5-lipoxygenase with arachidonic acid.

    PubMed

    Mittal, Monica; Kumar, Ramakrishnan B; Balagunaseelan, Navisraj; Hamberg, Mats; Jegerschöld, Caroline; Rådmark, Olof; Haeggström, Jesper Z; Rinaldo-Matthis, Agnes

    2016-08-01

    Human 5-lipoxygenase (5-LOX) is responsible for the formation of leukotriene (LT)A4, a pivotal intermediate in the biosynthesis of the leukotrienes, a family of proinflammatory lipid mediators. 5-LOX has thus gained attention as a potential drug target. However, details of the kinetic mechanism of 5-LOX are still obscure. In this Letter, we investigated the kinetic isotope effect (KIE) of 5-LOX with its physiological substrate, arachidonic acid (AA). The observed KIE is 20±4 on kcat and 17±2 on kcat/KM at 25°C indicating a non-classical reaction mechanism. The observed rates show slight temperature dependence at ambient temperatures ranging from 4 to 35°C. Also, we observed low Arrhenius prefactor ratio (AH/AD=0.21) and a small change in activation energy (Ea(D)-Ea(H)=3.6J/mol) which suggests that 5-LOX catalysis involves tunneling as a mechanism of H-transfer. The measured KIE for 5-LOX involves a change in regioselectivity in response to deuteration at position C7, resulting in H-abstraction form C10 and formation of 8-HETE. The viscosity experiments influence the (H)kcat, but not (D)kcat. However the overall kcat/KM is not affected for labeled or unlabeled AA, suggesting that either the product release or conformational rearrangement might be involved in dictating kinetics of 5-LOX at saturating conditions. Investigation of available crystal structures suggests the role of active site residues (F421, Q363 and L368) in regulating the donor-acceptor distances, thus affecting H-transfer as well as regiospecificity. In summary, our study shows that that the H-abstraction is the rate limiting step for 5-LOX and that the observed KIE of 5-LOX is masked by a change in regioselectivity. PMID:27363940

  2. 5-Lipoxygenase Deficiency Reduces Acetaminophen-Induced Hepatotoxicity and Lethality

    PubMed Central

    Hohmann, Miriam S. N.; Cardoso, Renato D. R.; Pinho-Ribeiro, Felipe A.; Crespigio, Jefferson; Cunha, Thiago M.; Alves-Filho, José C.; da Silva, Rosiane V.; Pinge-Filho, Phileno; Ferreira, Sergio H.; Cunha, Fernando Q.; Casagrande, Rubia; Verri, Waldiceu A.

    2013-01-01

    5-Lipoxygenase (5-LO) converts arachidonic acid into leukotrienes (LTs) and is involved in inflammation. At present, the participation of 5-LO in acetaminophen (APAP)-induced hepatotoxicity and liver damage has not been addressed. 5-LO deficient (5-LO−/−) mice and background wild type mice were challenged with APAP (0.3–6 g/kg) or saline. The lethality, liver damage, neutrophil and macrophage recruitment, LTB4, cytokine production, and oxidative stress were assessed. APAP induced a dose-dependent mortality, and the dose of 3 g/kg was selected for next experiments. APAP induced LTB4 production in the liver, the primary target organ in APAP toxicity. Histopathological analysis revealed that 5-LO−/− mice presented reduced APAP-induced liver necrosis and inflammation compared with WT mice. APAP-induced lethality, increase of plasma levels of aspartate aminotransferase and alanine aminotransferase, liver cytokine (IL-1β, TNF-α, IFN-γ, and IL-10), superoxide anion, and thiobarbituric acid reactive substances production, myeloperoxidase and N-acetyl-β-D-glucosaminidase activity, Nrf2 and gp91phox mRNA expression, and decrease of reduced glutathione and antioxidant capacity measured by 2,2′-azinobis(3-ethylbenzothiazoline 6-sulfonate) assay were prevented in 5-LO−/− mice compared to WT mice. Therefore, 5-LO deficiency resulted in reduced mortality due to reduced liver inflammatory and oxidative damage, suggesting 5-LO is a promising target to reduce APAP-induced lethality and liver inflammatory/oxidative damage. PMID:24288682

  3. Arachidonate 5-lipoxygenase (ALOX5) gene polymorphism is associated with Alzheimer's disease and body mass index.

    PubMed

    Šerý, Omar; Hlinecká, Lýdia; Povová, Jana; Bonczek, Ondřej; Zeman, Tomáš; Janout, Vladimír; Ambroz, Petr; Khan, Naim A; Balcar, Vladimir J

    2016-03-15

    Dementias of old age, in particular Alzheimer's disease (AD), pose a growing threat to the longevity and quality of life of individuals as well as whole societies world-wide. The risk factors are both genetic and environmental (life-style) and there is an overlap with similar factors predisposing to cardiovascular diseases (CVD). Using a case-control genetic approach, we have identified a SNP (rs10507391) in ALOX5 gene, previously associated with an increased risk of stroke, as a novel genetic risk factor for AD. ALOX5 gene encodes a 5'-lipoxygenase (5'-LO) activating protein (FLAP), a crucial component of the arachidonic acid/leukotriene inflammatory cascade. A-allele of rs4769874 polymorphism increases the risk of AD 1.41-fold (p<0.0001), while AA genotype does so 1.79-fold (p<0.0001). In addition, GG genotype of rs4769874 polymorphism is associated with a modest increase in body mass index (BMI). We discuss potential biochemical mechanisms linking the SNP to AD and suggest possible preventive pharmacotherapies some of which are based on commonly available natural products. Finally, we set the newly identified AD risk factors into a broader context of similar CVD risk factors to generate a more comprehensive picture of interacting genetics and life-style habits potentially leading to the deteriorating mental health in the old age. PMID:26944113

  4. Electrophilic Fatty Acid Species Inhibit 5-Lipoxygenase and Attenuate Sepsis-Induced Pulmonary Inflammation

    PubMed Central

    Awwad, Khader; Steinbrink, Svenja D.; Frömel, Timo; Lill, Nicole; Isaak, Johann; Häfner, Ann-Kathrin; Roos, Jessica; Hofmann, Bettina; Heide, Heinrich; Geisslinger, Gerd; Steinhilber, Dieter; Freeman, Bruce A.; Maier, Thorsten J.; Fleming, Ingrid

    2014-01-01

    Abstract Aims: The reaction of nitric oxide and nitrite-derived species with polyunsaturated fatty acids yields electrophilic fatty acid nitroalkene derivatives (NO2-FA), which display anti-inflammatory properties. Given that the 5-lipoxygenase (5-LO, ALOX5) possesses critical nucleophilic amino acids, which are potentially sensitive to electrophilic modifications, we determined the consequences of NO2-FA on 5-LO activity in vitro and on 5-LO-mediated inflammation in vivo. Results: Stimulation of human polymorphonuclear leukocytes (PMNL) with nitro-oleic (NO2-OA) or nitro-linoleic acid (NO2-LA) (but not the parent lipids) resulted in the concentration-dependent and irreversible inhibition of 5-LO activity. Similar effects were observed in cell lysates and using the recombinant human protein, indicating a direct reaction with 5-LO. NO2-FAs did not affect the activity of the platelet-type 12-LO (ALOX12) or 15-LO-1 (ALOX15) in intact cells or the recombinant protein. The NO2-FA-induced inhibition of 5-LO was attributed to the alkylation of Cys418, and the exchange of Cys418 to serine rendered 5-LO insensitive to NO2-FA. In vivo, the systemic administration of NO2-OA to mice decreased neutrophil and monocyte mobilization in response to lipopolysaccharide (LPS), attenuated the formation of the 5-LO product 5-hydroxyeicosatetraenoic acid (5-HETE), and inhibited lung injury. The administration of NO2-OA to 5-LO knockout mice had no effect on LPS-induced neutrophil or monocyte mobilization as well as on lung injury. Innovation: Prophylactic administration of NO2-OA to septic mice inhibits inflammation and promotes its resolution by interfering in 5-LO-mediated inflammatory processes. Conclusion: NO2-FAs directly and irreversibly inhibit 5-LO and attenuate downstream acute inflammatory responses. Antioxid. Redox Signal. 20, 2667–2680. PMID:24206143

  5. 5-Lipoxygenase is a direct p53 target gene in humans.

    PubMed

    Gilbert, Bianca; Ahmad, Khalil; Roos, Jessica; Lehmann, Christoph; Chiba, Tomohiro; Ulrich-Rückert, Sandra; Smeenk, Leonie; van Heeringen, Simon; Maier, Thorsten J; Groner, Bernd; Steinhilber, Dieter

    2015-08-01

    The p53 tumor suppressor plays a critical role in cancer, and more than 50% of human tumors contain mutations or deletions of the TP53 gene. p53 can transactivate or repress target genes in response to diverse stress signals, such as transient growth arrest, DNA repair, cellular differentiation, senescence and apoptosis. Through an unbiased genome-wide ChIP-seq analysis, we have found that 5-lipoxygenase (ALOX5, 5-LO) which is a key enzyme of leukotriene (LT) biosynthesis, is a direct target gene of p53 and its expression is induced by genotoxic stress via actinomycin D (Act.D) or etoposide (Eto) treatment. 5-LO and LTs play a role in immunological diseases as well as in tumorigenesis and tumor growth. p53 binds to a specific binding site consisting of a complete p53 consensus-binding motif in ALOX5 intron G which is located about 64kbp downstream of the transcriptional start site. We confirmed the strong binding of p53 to the 5-LO target site in ChIP-qPCR experiments. Expression analyses by qRT-PCR and immunoblot further revealed that genotoxic stress induces the ALOX5 mRNA and protein expression in a p53-dependent manner. Knockdown of p53 in U2OS cells leads to a downregulation of 5-LO mRNA and protein expression. In addition, immunofluorescence and immunoprecipitation assays indicate the direct binding of 5-LO to p53 protein. Furthermore, we found that 5-LO can inhibit the transcriptional activity of p53 suggesting that 5-LO acts in a negative feedback loop to limit induction of p53 target genes.

  6. 5-Lipoxygenase-dependent apoptosis of human lymphocytes in the International Space Station: data from the ROALD experiment.

    PubMed

    Battista, Natalia; Meloni, Maria A; Bari, Monica; Mastrangelo, Nicolina; Galleri, Grazia; Rapino, Cinzia; Dainese, Enrico; Agrò, Alessandro Finazzi; Pippia, Proto; Maccarrone, Mauro

    2012-05-01

    The functional adaptation of the immune system to the surrounding environment is also a fundamental issue in space. It has been suggested that a decreased number of lymphocytes might be a cause of immunosuppression, possibly due to the induction of apoptosis. Early activation of 5-lipoxygenase (5-LOX) might play a central role in the initiation of the apoptotic program. The goal of the role of apoptosis in lymphocyte depression (ROALD) experiment, flown on the International Space Station as part of the BIO-4 mission of the European Space Agency, was to ascertain the induction of apoptosis in human lymphocytes under authentic microgravity, and to elucidate the possible involvement of 5-LOX. Our results demonstrate that exposure of human lymphocytes to microgravity for 48 h onboard the ISS remarkably increased apoptotic hallmarks such as DNA fragmentation (∼3-fold compared to ground-based controls) and cleaved-poly (ADP-ribose) polymerase (PARP) protein expression (∼3-fold), as well as mRNA levels of apoptosis-related markers such as p53 (∼3-fold) and calpain (∼4-fold); these changes were paralleled by an early increase of 5-LOX activity (∼2-fold). Our findings provide a molecular background for the immune dysfunction observed in astronauts during space missions, and reveal potential new markers to monitor health status of ISS crew members.

  7. Meso-dihydroguaiaretic acid isolated from Saururus chinensis inhibits cyclooxygenase-2 and 5-lipoxygenase in mouse bone marrow-derived mast cells.

    PubMed

    Moon, Tae Chul; Seo, Chang Seob; Haa, Kyungmi; Kim, Jin Cheul; Hwang, Nam Kyung; Hong, Tae Gyun; Kim, Jee Hyeun; Kim, Do Hun; Son, Jong Keun; Chang, Hyeun Wook

    2008-05-01

    Meso-dihydroguaiaretic acid (MDGA) is a medicinal herbal product isolated from the aerial parts of Saururus chinensis that inhibits the cyclooxygenase-2 (COX-2)-dependent phase of prostaglandin D(2) (PGD(2)) generation in bone marrow-derived mast cells (BMMC) (IC(50) 9.8 microM). However, this compound did not inhibit COX-2 protein expression in BMMC at concentrations up to 30 microM, indicating that MDGA directly inhibits COX-2 activity. In addition, this compound consistently inhibited the production of leukotriene C(4) (IC(50) 1.3 microM). These results demonstrate that MDGA inhibits both COX-2 and 5-lipoxygenase. Furthermore, this compound strongly inhibited the degranulation reaction in BMMC (IC(50) 11.4 microM). Therefore, this compound might provide a basis for novel anti-inflammatory drug development.

  8. 5-Lipoxygenase inhibitors suppress RANKL-induced osteoclast formation via NFATc1 expression.

    PubMed

    Kang, Ju-Hee; Ting, Zheng; Moon, Mi-ran; Sim, Jung-Seon; Lee, Jung-Min; Doh, Kyung-Eun; Hong, Sunhye; Cui, Minghua; Choi, Sun; Chang, Hyeun Wook; Park Choo, Hea-Young; Yim, Mijung

    2015-11-01

    5-Lipoxygenase synthesizes leukotrienes from arachidonic acid. We developed three novel 5-LO inhibitors having a benzoxazole scaffold as a potential anti-osteoclastogenics. They significantly suppressed RANKL-induced osteoclast formation in mouse bone marrow-derived macrophages. Furthermore, one compound, K7, inhibited the bone resorptive activity of osteoclasts. The anti-osteoclastogenic effect of K7 was mainly attributable to reduction in the expression of NFATc1, an essential transcription factor for osteoclast differentiation. K7 inhibited osteoclast formation via ERK and p38 MAPK, as well as NF-κB signaling pathways. K7 reduced lipopolysaccharide (LPS)-induced osteoclast formation in vivo, corroborating the in vitro data. Thus, K7 exerted an inhibitory effect on osteoclast formation in vitro and in vivo, properties that make it a potential candidate for the treatment of bone diseases associated with excessive bone resorption.

  9. Naturally occurring biflavonoid, ochnaflavone, inhibits cyclooxygenases-2 and 5-lipoxygenase in mouse bone marrow-derived mast cells.

    PubMed

    Son, Min Jung; Moon, Tae Chul; Lee, Eun Kyung; Son, Kun Ho; Kim, Hyun Pyo; Kang, Sam Sik; Son, Jong Keun; Lee, Seung Ho; Chang, Hyeun Wook

    2006-04-01

    Ochnaflavone is a medicinal herbal product isolated from Lonicera japonica that inhibits cyclooxygenase-2 (COX-2) dependent phases of prostaglandin D2 (PGD2) generation in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with IC50 values of 0.6 microM. Western blotting probed with specific anti-COX-2 antibodies showed that the decrease in quantity of the PGD2 product was accompanied by a decrease in the COX-2 protein level. In addition, this compound consistently inhibited the production of leukotriene C4 (LTC4) in a dose dependent manner, with an IC50 value of 6.56 microM. These results demonstrate that ochnaflavone has a dual cyclooxygenase-2/5-lipoxygenase inhibitory activity. Furthermore, this compound strongly inhibited degranulation reaction in a dose dependent manner, with an IC50 value of 3.01 microM. Therefore, this compound might provide a basis for novel anti-inflammatory drugs.

  10. Structural and Functional Analysis of Calcium Ion Mediated Binding of 5-Lipoxygenase to Nanodiscs

    PubMed Central

    Kumar, Ramakrishnan B.; Zhu, Lin; Idborg, Helena; Rådmark, Olof; Jakobsson, Per-Johan; Rinaldo-Matthis, Agnes; Hebert, Hans; Jegerschöld, Caroline

    2016-01-01

    An important step in the production of inflammatory mediators of the leukotriene family is the Ca2+ mediated recruitment of 5 Lipoxygenase (5LO) to nuclear membranes. To study this reaction in vitro, the natural membrane mimicking environment of nanodiscs was used. Nanodiscs with 10.5 nm inner diameter were made with the lipid POPC and membrane scaffolding protein MSP1E3D1. Monomeric and dimeric 5LO were investigated. Monomeric 5LO mixed with Ca2+ and nanodiscs are shown to form stable complexes that 1) produce the expected leukotriene products from arachidonic acid and 2) can be, for the first time, visualised by native gel electrophoresis and negative stain transmission electron microscopy and 3) show a highest ratio of two 5LO per nanodisc. We interpret this as one 5LO on each side of the disc. The dimer of 5LO is visualised by negative stain transmission electron microscopy and is shown to not bind to nanodiscs. This study shows the advantages of nanodiscs to obtain basic structural information as well as functional information of a complex between a monotopic membrane protein and the membrane. PMID:27010627

  11. Synthesis and Evaluation of 5-Lipoxygenase Translocation Inhibitors from Acylnitroso Hetero-Diels-Alder Cycloadducts†

    PubMed Central

    Bolger, Joshua K.; Tian, Wen; Wolter, William R.; Cho, Wonhwa; Suckow, Mark A.

    2012-01-01

    Acylnitroso cycloadducts have proven to be valuable intermediates in the syntheses of a plethora of biologically active molecules. Recently, organometallic reagents were shown to open bicyclic acylnitroso cycloadducts and, more interestingly, the prospect of highly regioselective openings was raised. This transformation was employed in the synthesis of a compound with excellent inhibitory activity against 5-lipoxygenase ((±)-4a, IC50 51 nM), an important mediator of inflammation intimately involved in a number of disease states including asthma and cancer. Optimization of the copper-mediated organometallic ring opening reaction was accomplished allowing the further exploration of the biological activity. Synthesis of a number of derivatives with varying affinity for metal binding as well as pendant groups in a range of sizes was accomplished. Analogues were tested in a whole cell assay which revealed a subset of the compounds to be inhibitors of enzyme translocation, a mode of action not previously known and, potentially, extremely important for better understanding of the enzyme and inhibitor development. Additionally, the lead compound was tested in vivo in an established colon cancer model and showed very encouraging anti-tumorogenic properties. PMID:21365098

  12. Synthesis and biological evaluation of novel pyrazolopyrimidines derivatives as anticancer and anti-5-lipoxygenase agents.

    PubMed

    Rahmouni, Ameur; Souiei, Sawssen; Belkacem, Mohamed Amine; Romdhane, Anis; Bouajila, Jalloul; Ben Jannet, Hichem

    2016-06-01

    A novel series of 6-aryl-3-methyl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-ones 3a-h were synthesized in a single step via condensation of carboxamide 2 with some aromatic aldehydes (presence of iodine). Treatment of aminopyrazole 1a with acetic anhydride afforded pyrazolopyrimidines 4 which on treatment with ethyl chloroacetate in refluxing dry DMF furnished a single product identified as ethyl 2-(3,6-dimethyl-4-oxo-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-5(4H)-yl) acetate 5. On the other hand, esterification of compound 6 with different alcohol, led to the formation of new esters linked pyrazolo[3,4-d]pyrimidinones hybrids 7a-f. The reaction of compound 2 with 3-propargyl bromide gave the compound 8 used as a dipolarophile to access to triazoles (4- and 5-regioisomers (9a-e) and (10a-e), respectively) via the 1,3-dipoar cycloaddition reaction. Finally, condensation reaction of aminopyrazole 1b with α-cyanocinnamonitiles gave the new pyrazolo[1,5-a]pyrimidine-3,6-dicarbonitriles 11a-e. Structures of compounds were established on the basis of (1)H/(13)C NMR and ESI-HRMS. Compounds were screened for their cytotoxic (HCT-116 and MCF-7) and 5-lipoxygenase inhibition activities. The structure-activity relationship (SAR) was discussed.

  13. Synthesis and biological evaluation of novel pyrazolopyrimidines derivatives as anticancer and anti-5-lipoxygenase agents.

    PubMed

    Rahmouni, Ameur; Souiei, Sawssen; Belkacem, Mohamed Amine; Romdhane, Anis; Bouajila, Jalloul; Ben Jannet, Hichem

    2016-06-01

    A novel series of 6-aryl-3-methyl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-ones 3a-h were synthesized in a single step via condensation of carboxamide 2 with some aromatic aldehydes (presence of iodine). Treatment of aminopyrazole 1a with acetic anhydride afforded pyrazolopyrimidines 4 which on treatment with ethyl chloroacetate in refluxing dry DMF furnished a single product identified as ethyl 2-(3,6-dimethyl-4-oxo-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-5(4H)-yl) acetate 5. On the other hand, esterification of compound 6 with different alcohol, led to the formation of new esters linked pyrazolo[3,4-d]pyrimidinones hybrids 7a-f. The reaction of compound 2 with 3-propargyl bromide gave the compound 8 used as a dipolarophile to access to triazoles (4- and 5-regioisomers (9a-e) and (10a-e), respectively) via the 1,3-dipoar cycloaddition reaction. Finally, condensation reaction of aminopyrazole 1b with α-cyanocinnamonitiles gave the new pyrazolo[1,5-a]pyrimidine-3,6-dicarbonitriles 11a-e. Structures of compounds were established on the basis of (1)H/(13)C NMR and ESI-HRMS. Compounds were screened for their cytotoxic (HCT-116 and MCF-7) and 5-lipoxygenase inhibition activities. The structure-activity relationship (SAR) was discussed. PMID:27179178

  14. A dual inhibitor of cyclooxygenase and 5-lipoxygenase protects against kainic acid-induced brain injury.

    PubMed

    Minutoli, Letteria; Marini, Herbert; Rinaldi, Mariagrazia; Bitto, Alessandra; Irrera, Natasha; Pizzino, Gabriele; Pallio, Giovanni; Calò, Margherita; Adamo, Elena Bianca; Trichilo, Vincenzo; Interdonato, Monica; Galfo, Federica; Squadrito, Francesco; Altavilla, Domenica

    2015-06-01

    Systemic administration of kainic acid causes inflammation and apoptosis in the brain, resulting in neuronal loss. Dual cyclooxygenase/5-lipoxygenase (COX/5-LOX) inhibitors could represent a possible neuroprotective approach in preventing glutamate excitotoxicity. Consequently, we investigated the effects of a dual inhibitor of COX/5-LOX following intraperitoneal administration of kainic acid (KA, 10 mg/kg) in rats. Animals were randomized to receive either the dual inhibitor of COX/5-LOX (flavocoxid, 20 mg/kg i.p.) or its vehicle (1 ml/kg i.p.) 30 min after KA administration. Sham brain injury rats were used as controls. We evaluated protein expression of phosphorylated extracellular signal-regulated kinase (p-ERK1/2) and tumor necrosis factor alpha (TNF-α) as well as levels of malondialdehyde (MDA), prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) in the hippocampus. Animals were also observed for monitoring behavioral changes according to Racine Scale. Finally, histological analysis and brain edema evaluation were carried out. Treatment with the dual inhibitor of COX/5-LOX decreased protein expression of p-ERK1/2 and TNF-α in hippocampus, markedly reduced MDA, LTB4 and PGE2 hippocampal levels, and also ameliorated brain edema. Histological analysis showed a reduction in cell damage in rats treated with the dual inhibitor of COX/5-LOX, particularly in hippocampal subregion CA3c. Moreover, flavocoxid significantly improved behavioral signs following kainic acid administration. Our results suggest that dual inhibition of COX/5-LOX by flavocoxid has neuroprotective effects during kainic acid-induced excitotoxicity. PMID:25893744

  15. Effects of flavocoxid, a dual inhibitor of COX and 5-lipoxygenase enzymes, on benign prostatic hyperplasia

    PubMed Central

    Altavilla, D; Minutoli, L; Polito, F; Irrera, N; Arena, S; Magno, C; Rinaldi, M; Burnett, BP; Squadrito, F; Bitto, A

    2012-01-01

    BACKGROUND AND PURPOSE Inflammation plays a key role in the development of benign prostatic hyperplasia (BPH). Eicosanoids derived from the COX and 5-lipoxygenase (5-LOX) pathways are elevated in the enlarging prostate. Flavocoxid is a novel flavonoid–based ‘dual inhibitor’ of the COX and 5-LOX enzymes. This study evaluated the effects of flavocoxid in experimental BPH. EXPERIMENTAL APPROACH Rats were treated daily with testosterone propionate (3 mg·kg−1 s.c.) or its vehicle for 14 days to induce BPH. Animals receiving testosterone were randomized to receive vehicle (1 mL·kg−1, i.p.) or flavocoxid (20 mg·kg−1, i.p.) for 14 days. Histological changes, eicosanoid content and mRNA and protein levels for apoptosis-related proteins and growth factors were assayed in prostate tissue. The effects of flavocoxid were also tested on human prostate carcinoma PC3 cells. KEY RESULTS Flavocoxid reduced prostate weight and hyperplasia, blunted inducible expression of COX-2 and 5-LOX as well as the increased production of PGE2 and leukotriene B4 (LTB4), enhanced pro-apoptotic Bax and caspase-9 and decreased the anti-apoptotic Bcl-2 mRNA. Flavocoxid also reduced EGF and VEGF expression. In PC3 cells, flavocoxid stimulated apoptosis and inhibited growth factor expression. Flavocoxid-mediated induction of apoptosis was inhibited by the pan-caspase inhibitor, Z-VAD-FMK, in PC3 cells, suggesting an essential role of caspases in flavocoxid-mediated apoptosis during prostatic growth. CONCLUSION AND IMPLICATIONS Our results show that a ‘dual inhibitor’ of the COX and 5-LOX enzymes, such as flavocoxid, might represent a rational approach to reduce BPH through modulation of eicosanoid production and a caspase-induced apoptotic mechanism. PMID:22471974

  16. Pharmacophore modeling and virtual screening for designing potential 5-lipoxygenase inhibitors.

    PubMed

    Aparoy, P; Kumar Reddy, K; Kalangi, Suresh K; Chandramohan Reddy, T; Reddanna, P

    2010-02-01

    Inhibitors of the 5-Lipoxygenase (5-LOX) pathway have a therapeutic potential in a variety of inflammatory disorders such as asthma. In this study, chemical feature based pharmacophore models of inhibitors of 5-LOX have been developed with the aid of HipHop and HypoGen modules within Catalyst program package. The best quantitative pharmacophore model, Hypo1, which has the highest correlation coefficient (0.97), consists of two hydrogen-bond acceptors, one hydrophobic feature and one ring aromatic feature. Hypo1 was further validated by test set and cross validation method. The application of the model shows great success in predicting the activities of 65 known 5-LOX inhibitors in our test set with a correlation coefficient of 0.85 with a cross validation of 95% confidence level, proving that the model is reliable in identifying structurally diverse compounds for inhibitory activity against 5-LOX. Furthermore, Hypo1 was used as a 3D query for screening Maybridge and NCI databases within catalyst and also drug like compounds obtained from Enamine Ltd, which follow Lipinski's rule of five. The hit compounds were subsequently subjected to filtering by docking and visualization, to identify the potential lead molecules. Finally 5 potential lead compounds, identified in the above process, were evaluated for their inhibitory activities. These studies resulted in the identification of two compounds with potent inhibition of 5-LOX activity with IC(50) of 14 microM and 35 microM, respectively. These studies thus validate the pharmacophore model generated and suggest the usefulness of the model in screening of various small molecule libraries and identification of potential lead compounds for 5-LOX inhibition. PMID:20045317

  17. Pharmacophore modeling and virtual screening for designing potential 5-lipoxygenase inhibitors.

    PubMed

    Aparoy, P; Kumar Reddy, K; Kalangi, Suresh K; Chandramohan Reddy, T; Reddanna, P

    2010-02-01

    Inhibitors of the 5-Lipoxygenase (5-LOX) pathway have a therapeutic potential in a variety of inflammatory disorders such as asthma. In this study, chemical feature based pharmacophore models of inhibitors of 5-LOX have been developed with the aid of HipHop and HypoGen modules within Catalyst program package. The best quantitative pharmacophore model, Hypo1, which has the highest correlation coefficient (0.97), consists of two hydrogen-bond acceptors, one hydrophobic feature and one ring aromatic feature. Hypo1 was further validated by test set and cross validation method. The application of the model shows great success in predicting the activities of 65 known 5-LOX inhibitors in our test set with a correlation coefficient of 0.85 with a cross validation of 95% confidence level, proving that the model is reliable in identifying structurally diverse compounds for inhibitory activity against 5-LOX. Furthermore, Hypo1 was used as a 3D query for screening Maybridge and NCI databases within catalyst and also drug like compounds obtained from Enamine Ltd, which follow Lipinski's rule of five. The hit compounds were subsequently subjected to filtering by docking and visualization, to identify the potential lead molecules. Finally 5 potential lead compounds, identified in the above process, were evaluated for their inhibitory activities. These studies resulted in the identification of two compounds with potent inhibition of 5-LOX activity with IC(50) of 14 microM and 35 microM, respectively. These studies thus validate the pharmacophore model generated and suggest the usefulness of the model in screening of various small molecule libraries and identification of potential lead compounds for 5-LOX inhibition.

  18. Effect of the 5-lipoxygenase inhibitor ZD2138 on aspirin-induced asthma.

    PubMed Central

    Nasser, S. M.; Bell, G. S.; Foster, S.; Spruce, K. E.; MacMillan, R.; Williams, A. J.; Lee, T. H.; Arm, J. P.

    1994-01-01

    BACKGROUND--The cysteinyl leukotrienes may play a central part in the mechanisms of aspirin-sensitive asthma. Previous work has shown that individuals with aspirin-sensitive asthma have high basal urinary LTE4 levels which increase further upon aspirin ingestion, and that sulphidopeptide leukotriene receptor antagonists attenuate aspirin-induced airflow obstruction. If the cysteinyl leukotrienes cause aspirin-induced asthmatic reactions, inhibition of the 5-lipoxygenase pathway should prevent aspirin-induced bronchospasm. This hypothesis has been tested with ZD2138, a specific non-redox 5-lipoxygenase inhibitor. METHODS--Seven subjects (four men) with aspirin-sensitive asthma with baseline FEV1 values > 67% were studied. ZD2138 (350 mg) or placebo was given on two separate occasions two weeks apart in a randomised double blind fashion. A single dose of aspirin was administered four hours after dosing and FEV1 was measured for six hours. Inhibition of the 5-lipoxygenase pathway by ZD2138 was assessed by measurements of urinary LTE4 levels and ex vivo calcium ionophore stimulated LTB4 generation in whole blood, before administration of drug or placebo and at regular time intervals after dosing and aspirin administration. RESULTS--ZD2138 protected against the aspirin-induced reduction in FEV1 with a 20.3 (4.9)% fall in FEV1 following placebo compared with 4.9 (2.9)% following ZD2138. This was associated with 72% inhibition of ex vivo LTB4 generation in whole blood at 12 hours and a 74% inhibition of the rise in urinary LTE4 excretion at six hours after aspirin ingestion. CONCLUSIONS--In aspirin-sensitive asthma the 5-lipoxygenase inhibitor ZD2138 inhibits the fall in FEV1 induced by aspirin and this is associated with substantial inhibition of 5-lipoxygenase. PMID:8091318

  19. On the interference of boswellic acids with 5-lipoxygenase: mechanistic studies in vitro and pharmacological relevance.

    PubMed

    Siemoneit, Ulf; Pergola, Carlo; Jazzar, Bianca; Northoff, Hinnak; Skarke, Carsten; Jauch, Johann; Werz, Oliver

    2009-03-15

    Boswellic acids are pharmacologically active ingredients of frankincense with anti-inflammatory properties. It was shown that in vitro 11-keto-boswellic acids inhibit 5-lipoxygenase (5-LO, EC 1.13.11.34), the key enzyme in leukotriene biosynthesis, which may account for their anti-inflammatory effectiveness. However, whether 11-keto-boswellic acids interfere with 5-LO under physiologically relevant conditions (i.e., in whole blood assays) and whether they inhibit 5-LO in vivo is unknown. Inhibition of human 5-LO by the major naturally occurring boswellic acids was analyzed in cell-free and cell-based activity assays. Moreover, interference of boswellic acids with 5-LO in neutrophil incubations in the presence of albumin and in human whole blood was assessed, and plasma leukotriene B(4) of frankincense-treated healthy volunteers was determined. Factors influencing 5-LO activity (i.e., Ca(2+), phospholipids, substrate concentration) significantly modulate the potency of 11-keto-boswellic acids to inhibit 5-LO. Moreover, 11-keto-boswellic acids efficiently suppressed 5-LO product formation in isolated neutrophils (IC(50)=2.8 to 8.8 muM) but failed to inhibit 5-LO product formation in human whole blood. In the presence of albumin (10 mg/ml), 5-LO inhibition by 11-keto-boswellic acids (up to 30 muM) in neutrophils was abolished, apparently due to strong albumin-binding (>95%) of 11-keto-boswellic acids. Finally, single dose (800 mg) oral administration of frankincense extracts to human healthy volunteers failed to suppress leukotriene B(4) plasma levels. Our data show that boswellic acids are direct 5-LO inhibitors that efficiently suppress 5-LO product synthesis in common in vitro test models, however, the pharmacological relevance of such interference in vivo seems questionable.

  20. On the inhibition of 5-lipoxygenase product formation by tryptanthrin: mechanistic studies and efficacy in vivo

    PubMed Central

    Pergola, C; Jazzar, B; Rossi, A; Northoff, H; Hamburger, M; Sautebin, L; Werz, O

    2012-01-01

    BACKGROUND AND PURPOSE Leukotrienes (LTs) are pro-inflammatory mediators produced by 5-lipoxygenase (5-LO). Currently available 5-LO inhibitors either lack efficacy or are toxic and novel approaches are required to establish a successful anti-LT therapy. Here we provide a detailed evaluation of the effectiveness of the plant-derived alkaloid tryptanthrin as an inhibitor of LT biosynthesis. EXPERIMENTAL APPROACH We analysed LT formation and performed mechanistic studies in human neutrophils stimulated with pathophysiologically relevant stimuli (LPS and formyl peptide), as well as in cell-free assays (neutrophil homogenates or recombinant human 5-LO) and in human whole blood. The in vivo effectiveness of tryptanthrin was evaluated in the rat model of carrageenan-induced pleurisy. KEY RESULTS Tryptanthrin potently reduced LT-formation in human neutrophils (IC50 = 0.6 µM). However, tryptanthrin is not a redox-active compound and did not directly interfere with 5-LO activity in cell-free assays. Similarly, tryptanthrin did not inhibit the release of arachidonic acid, the activation of MAPKs, or the increase in [Ca2+]i, but it modified the subcellular localization of 5-LO. Moreover, tryptanthrin potently suppressed LT formation in human whole blood (IC50 = 10 µM) and reduced LTB4 levels in the rat pleurisy model after a single oral dose of 10 mg·kg−1. CONCLUSIONS AND IMPLICATIONS Our data reveal that tryptanthrin is a potent natural inhibitor of cellular LT biosynthesis with proven efficacy in whole blood and is effective in vivo after oral administration. Its unique pharmacological profile supports further analysis to exploit its pharmacological potential. PMID:21797843

  1. Regulation of tumorigenic Wnt signaling by cyclooxygenase-2, 5-lipoxygenase and their pharmacological inhibitors: A basis for novel drugs targeting cancer cells?

    PubMed

    Roos, Jessica; Grösch, Sabine; Werz, Oliver; Schröder, Peter; Ziegler, Slava; Fulda, Simone; Paulus, Patrick; Urbschat, Anja; Kühn, Benjamin; Maucher, Isabelle; Fettel, Jasmin; Vorup-Jensen, Thomas; Piesche, Matthias; Matrone, Carmela; Steinhilber, Dieter; Parnham, Michael J; Maier, Thorsten J

    2016-01-01

    Canonical Wnt signaling is a highly conserved pathway with a prominent role in embryogenic development, adult tissue homeostasis, cell polarization, stem cell biology, cell differentiation, and proliferation. Furthermore, canonical Wnt signaling is of pivotal importance in the pathogenesis of a number of cancer types and crucially affects tumor initiation, cancer cell proliferation, cancer cell apoptosis, and metastasis. Reports over the last decade have provided strong evidence for a pathophysiological role of Wnt signaling in non-malignant classical inflammatory and neurodegenerative diseases. Although, several agents suppressing the Wnt pathway at different levels have been identified, the development of clinically relevant Wnt-inhibiting agents remains challenging due to selectivity and toxicity issues. Several studies have shown that long-term administration of non-steroidal anti-inflammatory drugs protects against colon cancer and potentially other tumor types by interfering both with the COX and the Wnt pathway. Our own studies have shown that non-steroidal anti-inflammatory drugs suppress Wnt signaling by targeting the pro-inflammatory enzyme 5-lipoxygenase which is the key enzyme pathophysiologically involved in the synthesis of leukotrienes. Furthermore, we found a direct link between the 5-lipoxygenase and Wnt signaling pathways, which is essential for the maintenance of leukemic stem cells. Accordingly, genetic and pharmacological inhibition of 5-lipoxygenase led to an impairment of Wnt-dependent acute and chronic myeloid leukemic stem cells. We believe that 5-lipoxygenase inhibitors might represent a novel type of Wnt inhibitor activating a potentially naturally occurring novel mechanism of suppression of Wnt signaling that is non-toxic, at least in mice, and is potentially well tolerated in patients.

  2. Design, synthesis and evaluation of semi-synthetic triazole-containing caffeic acid analogues as 5-lipoxygenase inhibitors.

    PubMed

    De Lucia, Daniela; Lucio, Oscar Méndez; Musio, Biagia; Bender, Andreas; Listing, Monika; Dennhardt, Sophie; Koeberle, Andreas; Garscha, Ulrike; Rizzo, Roberta; Manfredini, Stefano; Werz, Oliver; Ley, Steven V

    2015-08-28

    In this work the synthesis, structure-activity relationship (SAR) and biological evaluation of a novel series of triazole-containing 5-lipoxygenase (5-LO) inhibitors are described. The use of structure-guided drug design techniques provided compounds that demonstrated excellent 5-LO inhibition with IC50 of 0.2 and 3.2 μm in cell-based and cell-free assays, respectively. Optimization of binding and functional potencies resulted in the identification of compound 13d, which showed an enhanced activity compared to the parent bioactive compound caffeic acid 5 and the clinically approved zileuton 3. Compounds 15 and 16 were identified as lead compounds in inhibiting 5-LO products formation in neutrophils. Their interference with other targets on the arachidonic acid pathway was also assessed. Cytotoxicity tests were performed to exclude a relationship between cytotoxicity and the increased activity observed after structure optimization.

  3. Computational insight into the catalytic implication of head/tail-first orientation of arachidonic acid in human 5-lipoxygenase: consequences for the positional specificity of oxygenation.

    PubMed

    Saura, Patricia; Maréchal, Jean-Didier; Masgrau, Laura; Lluch, José M; González-Lafont, Àngels

    2016-08-17

    In the present work we have combined homology modeling, protein-ligand dockings, quantum mechanics/molecular mechanics calculations and molecular dynamics simulations to generate human 5-lipoxygenase (5-LOX):arachidonic acid (AA) complexes consistent with the 5-lipoxygenating activity (which implies hydrogen abstraction at the C7 position). Our results suggest that both the holo and the apo forms of human Stable 5-LOX could accommodate AA in a productive form for 5-lipoxygenation. The former, in a tail-first orientation, with the AA carboxylate end interacting with Lys409, gives the desired structures with C7 close to the Fe-OH(-) cofactor and suitable barrier heights for H7 abstraction. Only when using the apo form structure, a head-first orientation with the AA carboxylate close to His600 (a residue recently proposed as essential for AA positioning) is obtained in the docking calculations. However, the calculated barrier heights for this head-first orientation are in principle consistent with 5-LOX specificity, but also with 12/8 regioselectivity. Finally, long MD simulations give support to the recent hypothesis that the Phe177 + Tyr181 pair needs to close the active site access during the chemical reaction, and suggest that in the case of a head-first orientation Phe177 may be the residue interacting with the AA carboxylate. PMID:27489112

  4. Analysis of a nucleotide-binding site of 5-lipoxygenase by affinity labelling: binding characteristics and amino acid sequences.

    PubMed Central

    Zhang, Y Y; Hammarberg, T; Radmark, O; Samuelsson, B; Ng, C F; Funk, C D; Loscalzo, J

    2000-01-01

    5-Lipoxygenase (5LO) catalyses the first two steps in the biosynthesis of leukotrienes, which are inflammatory mediators derived from arachidonic acid. 5LO activity is stimulated by ATP; however, a consensus ATP-binding site or nucleotide-binding site has not been found in its protein sequence. In the present study, affinity and photoaffinity labelling of 5LO with 5'-p-fluorosulphonylbenzoyladenosine (FSBA) and 2-azido-ATP showed that 5LO bound to the ATP analogues quantitatively and specifically and that the incorporation of either analogue inhibited ATP stimulation of 5LO activity. The stoichiometry of the labelling was 1.4 mol of FSBA/mol of 5LO (of which ATP competed with 1 mol/mol) or 0.94 mol of 2-azido-ATP/mol of 5LO (of which ATP competed with 0.77 mol/mol). Labelling with FSBA prevented further labelling with 2-azido-ATP, indicating that the same binding site was occupied by both analogues. Other nucleotides (ADP, AMP, GTP, CTP and UTP) also competed with 2-azido-ATP labelling, suggesting that the site was a general nucleotide-binding site rather than a strict ATP-binding site. Ca(2+), which also stimulates 5LO activity, had no effect on the labelling of the nucleotide-binding site. Digestion with trypsin and peptide sequencing showed that two fragments of 5LO were labelled by 2-azido-ATP. These fragments correspond to residues 73-83 (KYWLNDDWYLK, in single-letter amino acid code) and 193-209 (FMHMFQSSWNDFADFEK) in the 5LO sequence. Trp-75 and Trp-201 in these peptides were modified by the labelling, suggesting that they were immediately adjacent to the C-2 position of the adenine ring of ATP. Given the stoichiometry of the labelling, the two peptide sequences of 5LO were probably near each other in the enzyme's tertiary structure, composing or surrounding the ATP-binding site of 5LO. PMID:11042125

  5. Syntheses and evaluation of novel isoliquiritigenin derivatives as potential dual inhibitors for amyloid-beta aggregation and 5-lipoxygenase.

    PubMed

    Chen, Yi-Ping; Zhang, Zi-Ying; Li, Yan-Ping; Li, Ding; Huang, Shi-Liang; Gu, Lian-Quan; Xu, Jun; Huang, Zhi-Shu

    2013-08-01

    A series of new isoliquiritigenin (ISL) derivatives were synthesized and evaluated as dual inhibitors for amyloid-beta (Aβ) aggregation and 5-lipoxygenase (5-LO). It was found that all these synthetic compounds inhibited Aβ (1-42) aggregation effectively with their IC₅₀ values ranged from 2.2 ± 1.5 μM to 23.8 ± 2.0 μM. These derivatives also showed inhibitory activity to 5-LO with their IC50 values ranged from 6.1 ± 0.1 μM to 35.9 ± 0.3 μM. Their structure-activity relationships (SAR) and mechanisms of inhibitions were studied. This study provided potentially important information for further development of ISL derivatives as multifunctional agents for Alzheimer's disease (AD) treatment.

  6. 5-lipoxygenase pathway is essential for the control of granuloma extension induced by Schistosoma mansoni eggs in lung.

    PubMed

    Toffoli da Silva, Gabriel; Espíndola, Milena Sobral; Fontanari, Caroline; Rosada, Rogerio Silva; Faccioli, Lúcia Helena; Ramos, Simone Gusmão; Rodrigues, Vanderlei; Frantz, Fabiani Gai

    2016-08-01

    According to WHO, it is estimated that approximately 2 billion people are infected with intestinal helminths worldwide and the number of people who are cured of these diseases is relatively low, resulting in a large percentage of chronically infected individuals. Schistosomiasis is one of the most important parasitic diseases present in developing countries configuring it as a serious public health problem, directly related to poverty and social disadvantage. Once the parasite infection is established, Schistosoma mansoni eggs fall into the bloodstream and are trapped in the liver microcirculation where a strong granulomatous response and fibrosis formation occurs. In the experimental model, granulomas develop in the mouse lung after intravenous injection of purified eggs. Here we aim to understand how leukotrienes are involved in the granuloma formation. Leukotrienes are lipid mediators derived from arachidonic acid metabolites via 5-lipoxygenase (5LO) enzyme. They are potent proinflammatory agents and induce recruitment, cell activation, regulation of microbicidal activity of polymorphonuclear and mononuclear cells. In this study, 5LO deficient mice (5LO(-/-)) were inoculated with S. mansoni eggs for evaluation of immunopathological parameters involved in the induction of type 2 granulomas. We showed that in the absence of leukotrienes, the size of granulomas were decreased comparing to the wild type mice and the inflammatory compromised areas had a lower extension. In 5LO(-/-) mice granulomas presented extensive areas of fibrosis, detected by α-SMA expression along the lesions, indicating remodeling in attempt to reestablish the normal tissue. Also, comparing to WT mice we detected decrease of IL-4 and IL-13 and increase of TGF-β in the lung of 5LO(-/-), but these mice failed to produce protective IFN-γ and IL-12. These results evidenced 5-Lipoxygenase as an important pathway during lung injury due to Schistosoma-eggs injection. PMID:27262746

  7. A Novel Inhibitor of 5-Lipoxygenase (5-LOX) Prevents Oxidative Stress–Induced Cell Death of Retinal Pigment Epithelium (RPE) Cells

    PubMed Central

    Subramanian, Preeti; Mendez, Emily F.; Becerra, S. Patricia

    2016-01-01

    Purpose 5-Lipoxygenase (5-LOX) oxygenates arachidonic acid to form 5-hydroperoxyeicosatetraenoic acid, which is further converted into biologically detrimental leukotrienes, such as leukotriene B4 (LTB4). The RPE and retina express the PNPLA2 gene for pigment epithelium–derived factor receptor (PEDF-R), a lipase involved in cell survival. The purpose here was to investigate the role of PEDF-R on the 5-LOX pathway in oxidative stress of RPE. Methods Lipoxygenase activity assays were performed with soybean and potato lipoxygenase. Binding was evaluated by peptide-affinity chromatography and pull-down assays with PEDF-R–derived synthetic peptides or recombinant protein. Oxidative stress was induced in human ARPE-19 and primary pig RPE cells with indicated concentrations of H2O2/TNF-α. Reverse transcription–PCR of ALOX5 and PNPLA2 genes was performed. Cell viability and death rates were determined using respective biomarkers. Leukotriene B4 levels were measured by ELISA. Results Among five peptides spanning between positions Leu159 and Met325 of human PEDF-R polypeptide, only two overlapping peptides, E5b and P1, bound and inhibited lipoxygenase activity. Human recombinant 5-LOX bound specifically to peptide P1 and to His6/Xpress-tagged PEDF-R via ionic interactions. The two inhibitor peptides E5b and P1 promoted cell viability and decreased cell death of RPE cells undergoing oxidative stress. Oxidative stress decreased the levels of PNPLA2 transcripts with no effect on ALOX5 expression. Exogenous additions of P1 peptide or overexpression of the PNPLA2 gene decreased both LTB4 levels and death of RPE cells undergoing oxidative stress. Conclusions A novel peptide region of PEDF-R inhibits 5-LOX, which intersects with RPE cell death pathways induced by oxidative stress. PMID:27635633

  8. Conversion of human 5-lipoxygenase to a 15-lipoxygenase by a point mutation to mimic phosphorylation at Serine-663

    SciTech Connect

    Gilbert, Nathaniel C.; Rui, Zhe; Neau, David B.; Waight, Maria T.; Bartlett, Sue G.; Boeglin, William E.; Brash, Alan R.; Newcomer, Marcia E.

    2012-08-31

    The enzyme 5-lipoxygenase (5-LOX) initiates biosynthesis of the proinflammatory leukotriene lipid mediators and, together with 15-LOX, is also required for synthesis of the anti-inflammatory lipoxins. The catalytic activity of 5-LOX is regulated through multiple mechanisms, including Ca{sup 2+}-targeted membrane binding and phosphorylation at specific serine residues. To investigate the consequences of phosphorylation at S663, we mutated the residue to the phosphorylation mimic Asp, providing a homogenous preparation suitable for catalytic and structural studies. The S663D enzyme exhibits robust 15-LOX activity, as determined by spectrophotometric and HPLC analyses, with only traces of 5-LOX activity remaining; synthesis of the anti-inflammatory lipoxin A4 from arachidonic acid is also detected. The crystal structure of the S663D mutant in the absence and presence of arachidonic acid (in the context of the previously reported Stable-5-LOX) reveals substantial remodeling of helices that define the active site so that the once fully encapsulated catalytic machinery is solvent accessible. Our results suggest that phosphorylation of 5-LOX at S663 could not only down-regulate leukotriene synthesis but also stimulate lipoxin production in inflammatory cells that do not express 15-LOX, thus redirecting lipid mediator biosynthesis to the production of proresolving mediators of inflammation.

  9. Structural optimization and biological evaluation of 1,5-disubstituted pyrazole-3-carboxamines as potent inhibitors of human 5-lipoxygenase

    PubMed Central

    Zhou, Yu; Liu, Jun; Zheng, Mingyue; Zheng, Shuli; Jiang, Chunyi; Zhou, Xiaomei; Zhang, Dong; Zhao, Jihui; Ye, Deju; Zheng, Mingfang; Jiang, Hualiang; Liu, Dongxiang; Cheng, Jian; Liu, Hong

    2016-01-01

    Human 5-lipoxygenase (5-LOX) is a well-validated drug target and its inhibitors are potential drugs for treating leukotriene-related disorders. Our previous work on structural optimization of the hit compound 2 from our in-house collection identified two lead compounds, 3a and 3b, exhibiting a potent inhibitory profile against 5-LOX with IC50 values less than 1 µmol/L in cell-based assays. Here, we further optimized these compounds to prepare a class of novel pyrazole derivatives by opening the fused-ring system. Several new compounds exhibited more potent inhibitory activity than the lead compounds against 5-LOX. In particular, compound 4e not only suppressed lipopolysaccharide-induced inflammation in brain inflammatory cells and protected neurons from oxidative toxicity, but also significantly decreased infarct damage in a mouse model of cerebral ischemia. Molecular docking analysis further confirmed the consistency of our theoretical results and experimental data. In conclusion, the excellent in vitro and in vivo inhibitory activities of these compounds against 5-LOX suggested that these novel chemical structures have a promising therapeutic potential to treat leukotriene-related disorders. PMID:26904397

  10. Repeated allergen exposure reduce early phase airway response and leukotriene release despite upregulation of 5-lipoxygenase pathways

    PubMed Central

    2012-01-01

    Background Allergen induced early phase airway response and airway plasma exudation are predominantly mediated by inflammatory mast cell mediators including histamine, cysteinyl leukotrienes (cysLTs) and thromboxane A2 (TXA2). The aim of the present study was to evaluate whether repeated allergen exposure affects early phase airway response to allergen challenge. Methods A trimellitic anhydride (TMA) sensitized guinea pig model was used to investigate the effects of low dose repeated allergen exposure on cholinergic airway responsiveness, early phase airway response and plasma exudation, as well as local airway production of mast cell derived cysteinyl leukotrienes and thromboxane B2 (TXB2) after allergen challenge. Results Repeated low dose allergen exposure increased cholinergic airway responsiveness. In contrast, early phase airway response and plasma exudation in response to a high-dose allergen challenge were strongly attenuated after repeated low dose allergen exposure. Inhibition of the airway response was unspecific to exposed allergen and independent of histamine receptor blocking. Furthermore, a significant reduction of cysteinyl leukotrienes and TXB2 was found in the airways of animals repeatedly exposed to a low dose allergen. However, in vitro stimulation of airway tissue from animals repeatedly exposed to a low dose allergen with arachidonic acid and calcium ionophore (A23187) induced production of cysteinyl leukotrienes and TXB2, suggesting enhanced activity of 5-lipoxygenase and cyclooxygenase pathways. Conclusions The inhibition of the early phase airway response, cysteinyl leukotriene and TXB2 production after repeated allergen exposure may result from unresponsive effector cells. PMID:22439792

  11. 5-Lipoxygenase gene transfer worsens memory, amyloid and tau brain pathologies in a mouse model of AD

    PubMed Central

    Chu, Jin; Giannopoulos, Phillip F.; Ceballos-Diaz, Carolina; Golde, Todd E.; Pratico, Domenico

    2012-01-01

    Objective The 5-lipoxygenase (5LO) enzyme is up-regulated in Alzheimer’s disease (AD), and its genetic absence reduces Aβ levels in APP mice. However, its functional role in modulating tau neuropathology remains to be elucidated. Methods To this end, we generated triple transgenic mice (3xTg-AD) over-expressing neuronal 5LO and investigated their phenotype. Results Compared with controls, 3xTg-AD mice over-expressing 5LO manifested an exacerbation of memory deficits, plaques and tangles pathologies. The elevation in Aβ was secondary to an up-regulation of γ-secretase pathway, whereas tau hyperphosphorylation resulted from an activation of the Cdk5 kinase. In vitro study confirmed the involvement of this kinase in the 5-LO-dependent tau phosphorylation, which was independent of the effect on Aβ. Interpretation Our findings highlight the novel functional role that neuronal 5LO plays in exacerbating AD-related tau pathologies. They provide critical preclinical evidence to justify testing selective 5LO inhibitors for AD treatment. PMID:23034916

  12. One-step semisynthesis of oleacein and the determination as a 5-lipoxygenase inhibitor.

    PubMed

    Vougogiannopoulou, Konstantina; Lemus, Christelle; Halabalaki, Maria; Pergola, Carlo; Werz, Oliver; Smith, Amos B; Michel, Sylvie; Skaltsounis, Leandros; Deguin, Brigitte

    2014-03-28

    The dialdehydes oleacein (2) and oleocanthal (4) are closely related to oleuropein (1) and ligstroside (3), the two latter compounds being abundant iridoids of Olea europaea. By exploiting oleuropein isolated from the plant leaf extract, an efficient procedure has been developed for a one-step semisynthesis of oleacein under Krapcho decarbomethoxylation conditions. Highlighted is the fact that 5-lipoxygenase is a direct target for oleacein with an inhibitory potential (IC50: 2 μM) more potent than oleocanthal (4) and oleuropein (1). This enzyme catalyzes the initial steps in the biosynthesis of pro-inflammatory leukotrienes. Taken together, the methodology presented here offers an alternative solution to isolation or total synthesis for the procurement of oleacein, thus facilitating the further development as a potential anti-inflammatory agent. PMID:24568174

  13. Gene expression of 5-lipoxygenase and LTA4 hydrolase in renal tissue of nephrotic syndrome patients

    PubMed Central

    Menegatti, E; Roccatello, D; Fadden, K; Piccoli, G; De Rosa, G; Sena, L M; Rifai, A

    1999-01-01

    Leukotrienes (LT) of the 5-lipoxygenase pathway constitute a class of potent biological lipid mediators of inflammation implicated in the pathogenesis of different models of experimental glomerulonephritis. The key enzyme, 5-lipoxygenase (5-LO), catalyses oxygenation of arachidonic acid to generate the primary leukotriene LTA4. This LT, in turn, serves as a substrate for either LTA4 hydrolase, to form the potent chemoattractant LTB4, or LTC4 synthase, to produce the powerful vasoconstrictor LTC4. To investigate the potential role of LT in the pathogenesis of human glomerulonephritis with nephrotic syndrome, we examined the gene expression of 5-LO and LTA4 hydrolase in renal tissue of 21 adult patients with nephrotic syndrome and 11 controls. The patients consisted of 11 cases of membranous nephropathy (MN), seven focal and segmental glomerulosclerosis (FSGS), two non-IgA mesangial glomerulonephritis and one minimal change disease. Total RNA purified from renal tissue was reverse transcribed into cDNA and amplified with specific primers in a polymerase chain reaction (RT-PCR). Eight patients' renal tissue, four MN and four FSGS, co-expressed 5-LO and LTA4 hydrolase. In situ hybridization analysis revealed 5-LO expression and distribution limited to the interstitial cells surrounding the peritubular capillaries. Comparative clinical and immunohistological data showed that these eight patients had impaired renal function and interstitial changes that significantly correlated with 5-LO expression. These findings suggest that leukotrienes may play an important role in the pathogenesis of MN and FSGS. These results are also relevant to elucidating the pathophysiologic mechanisms which underlie progression to renal failure in these diseases. PMID:10337029

  14. Caffeic acid phenethyl ester, a 5-lipoxygenase enzyme inhibitor, alleviates diabetic atherosclerotic manifestations: effect on vascular reactivity and stiffness.

    PubMed

    Hassan, Noura Ahmed; El-Bassossy, Hany M; Mahmoud, Mona Fouad; Fahmy, Ahmed

    2014-04-25

    Atherosclerosis is a major macrovascular complication of diabetes that increases the risks for myocardial infarction, stroke, and other vascular diseases. The effect of a selective 5-lipoxygenase enzyme inhibitor; caffeic acid phenethyl ester (CAPE) on diabetes-induced atherosclerotic manifestations was investigated. Insulin deficiency or resistance was induced by STZ or fructose respectively. Atherosclerosis developed when rats were left for 8 or 12 weeks subsequent STZ or fructose administration respectively. CAPE (30 mg kg(-1) day(-1)) was given in the last 6 weeks. Afterwards, blood pressure (BP) was recorded. Then, isolated aorta reactivity to KCl and phenylephrine (PE) was studied. Blood glucose level, serum levels of insulin, tumor necrosis factor α (TNF-α) as well as advanced glycation end products (AGEs) were determined. Moreover aortic haem oxygenase-1 (HO-1) protein expression and collagen deposition were also assessed. Insulin deficiency and resistance were accompanied with elevated BP, exaggerated response to KCl and PE, elevated serum TNF-α and AGEs levels. Both models showed marked increase in collagen deposition. However, CAPE alleviated systolic and diastolic BP elevations and the exaggerated vascular contractility to both PE and KCl in both models without affecting AGEs level. CAPE inhibited TNF-α serum level elevation, induced aortic HO-1 expression and reduced collagen deposition. CAPE prevented development of hyperinsulinemia in insulin resistance model without any impact on the developed hyperglycemia in insulin deficiency model. In conclusion, CAPE offsets the atherosclerotic changes associated with diabetes via amelioration of the significant functional and structural derangements in the vessels in addition to its antihyperinsulinemic effect in insulin resistant model.

  15. Preclinical toxicity evaluation of tepoxalin, a dual inhibitor of cyclooxygenase and 5-lipoxygenase, in Sprague-Dawley rats and beagle dogs.

    PubMed

    Knight, E V; Kimball, J P; Keenan, C M; Smith, I L; Wong, F A; Barrett, D S; Dempster, A M; Lieuallen, W G; Panigrahi, D; Powers, W J; Szot, R J

    1996-09-01

    Tepoxalin [5- (4-chlorophenyl)-N-hydroxy-1-(4-methoxyphenyl)-N-methyl-1H-pyrazole -3-propanamide] is an orally active anti-inflammatory agent, which inhibits both cyclooxygenase and 5-lipoxygenase activities. The oral toxicity of tepoxalin was evaluated in 1- and 6-month rat (up to 50 mg/kg/day) and dog (up to 150 mg/kg bid) studies. In rats, increased liver weight, centrilobular hypertrophy, and hepatic necrosis were observed at dosages >/=20 mg/kg/day. Renal changes indicative of analgesic nephropathy syndrome (i.e., papillary edema or necrosis, cortical tubular dilatation) were seen at >/=15 mg/kg. In rats treated for 1 month, these hepatic and renal effects were largely reversible after a 1-month recovery period. Gastrointestinal erosions and ulcers were seen in female rats given 40 mg/kg/day for 6 months. Changes in clinical pathology parameters included decreases in red blood cell count, hemoglobin, and hematocrit mean values; elevation in platelet counts; and an increase in prothrombin and activated partial thromboplastin times. Mild increases in alanine aminotransferase, aspartate aminotransferase, and cholesterol were also noted in rats. Decreased erythrocyte parameters, increased leukocyte counts, and decreased total protein, albumin, and/or calcium were noted in some dogs in the 300 mg/kg/day group following 6 months of dosing. Small pyloric ulcerations were seen at 100 and 300 mg/kg/day dosages for up to 6 months. In both rats and dogs, no accumulation of tepoxalin or its carboxylic acid metabolite was detected in plasma following multiple dosing over a range of 5 to 50 mg/kg/day for rats and 20 to 300 mg/kg/day for dogs. Plasma concentrations of the carboxylic acid metabolite were severalfold higher than those of the parent compound. The no-effect dosages in rats (5 mg/kg/day) and dogs (20 mg/kg/day) were approximately one and six times the ED50 (3.5 mg/kg), respectively, for inhibition of inflammatory effects in the adjuvant arthritic rat without

  16. 5-Lipoxygenase metabolite 4-HDHA is a mediator of the antiangiogenic effect of ω-3 polyunsaturated fatty acids.

    PubMed

    Sapieha, Przemyslaw; Stahl, Andreas; Chen, Jing; Seaward, Molly R; Willett, Keirnan L; Krah, Nathan M; Dennison, Roberta J; Connor, Kip M; Aderman, Christopher M; Liclican, Elvira; Carughi, Arianna; Perelman, Dalia; Kanaoka, Yoshihide; Sangiovanni, John Paul; Gronert, Karsten; Smith, Lois E H

    2011-02-01

    Lipid signaling is dysregulated in many diseases with vascular pathology, including cancer, diabetic retinopathy, retinopathy of prematurity, and age-related macular degeneration. We have previously demonstrated that diets enriched in ω-3 polyunsaturated fatty acids (PUFAs) effectively reduce pathological retinal neovascularization in a mouse model of oxygen-induced retinopathy, in part through metabolic products that suppress microglial-derived tumor necrosis factor-α. To better understand the protective effects of ω-3 PUFAs, we examined the relative importance of major lipid metabolic pathways and their products in contributing to this effect. ω-3 PUFA diets were fed to four lines of mice deficient in each key lipid-processing enzyme (cyclooxygenase 1 or 2, or lipoxygenase 5 or 12/15), retinopathy was induced by oxygen exposure; only loss of 5-lipoxygenase (5-LOX) abrogated the protection against retinopathy of dietary ω-3 PUFAs. This protective effect was due to 5-LOX oxidation of the ω-3 PUFA lipid docosahexaenoic acid to 4-hydroxy-docosahexaenoic acid (4-HDHA). 4-HDHA directly inhibited endothelial cell proliferation and sprouting angiogenesis via peroxisome proliferator-activated receptor γ (PPARγ), independent of 4-HDHA's anti-inflammatory effects. Our study suggests that ω-3 PUFAs may be profitably used as an alternative or supplement to current anti-vascular endothelial growth factor (VEGF) treatment for proliferative retinopathy and points to the therapeutic potential of ω-3 PUFAs and metabolites in other diseases of vasoproliferation. It also suggests that cyclooxygenase inhibitors such as aspirin and ibuprofen (but not lipoxygenase inhibitors such as zileuton) might be used without losing the beneficial effect of dietary ω-3 PUFA. PMID:21307302

  17. Age-dependent relevance of endogenous 5-lipoxygenase derivatives in anxiety-like behavior in mice.

    PubMed

    Leo, Luciana M; Almeida-Corrêa, Suellen; Canetti, Claudio A; Amaral, Olavo B; Bozza, Fernando A; Pamplona, Fabricio A

    2014-01-01

    When 5-lipoxygenase (5-LO) is inhibited, roughly half of the CNS effect of the prototypic endocannabinoid anandamide (AEA) is lost. Therefore, we decided to investigate whether inhibiting this enzyme would influence physiological functions classically described as being under control of the endocannabinoid system. Although 5-LO inhibition by MK-886 reduced lipoxin A4 levels in the brain, no effect was found in the elevated plus maze (EPM), even at the highest possible doses, via i.p. (10 mg/kg,) or i.c.v. (500 pmol/2 µl) routes. Accordingly, no alterations in anxiety-like behavior in the EPM test were observed in 5-LO KO mice. Interestingly, aged mice, which show reduced circulating lipoxin A4 levels, were sensitive to MK-886, displaying an anxiogenic-like state in response to treatment. Moreover, exogenous lipoxin A4 induced an anxiolytic-like profile in the EPM test. Our findings are in line with other reports showing no difference between FLAP KO or 5-LO KO and their control strains in adult mice, but increased anxiety-like behavior in aged mice. We also show for the first time that lipoxin A4 affects mouse behavior. In conclusion, we propose an age-dependent relevancy of endogenous 5-LO derivatives in the modulation of anxiety-like behavior, in addition to a potential for exogenous lipoxin A4 in producing an anxiolytic-like state.

  18. Novel di-tertiary-butyl phenylhydrazones as dual cyclooxygenase-2/5-lipoxygenase inhibitors: synthesis, COX/LOX inhibition, molecular modeling, and insights into their cytotoxicities.

    PubMed

    Ghatak, Shibnath; Vyas, Alok; Misra, Suniti; O'Brien, Paul; Zambre, Ajit; Fresco, Victor M; Markwald, Roger R; Swamy, K Venkateshwara; Afrasiabi, Zahra; Choudhury, Amitava; Khetmalas, Madhukar; Padhye, Subhash

    2014-01-01

    Although dual inhibition of Cyclooxygenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) enzymes is highly effective than targeting COX or LOX alone, there are only a few reports of examining such compounds in case of colorectal cancers (CRC). In the present work we report that the novel di-tert-butyl phenol-based dual inhibitors DTPSAL, DTPBHZ, DTPINH, and DTPNHZ exhibit significant cytotoxicity against human CRC cell lines. Molecular docking studies revealed a good fit of these compounds in the COX-2 and 5-LOX protein cavities. The inhibitors show significant inhibition of COX-2 and 5-LOX activities and are effective against a panel of human colon cancer cell lines including HCA-7, HT-29, SW480 and intestinal Apc10.1 cells as well as the hyaluronan synthase-2 (Has2) enzyme over-expressing colon cancer cells, through inhibition of the Hyaluronan/CD44v6 cell survival pathway. Western blot analysis and qRT-PCR analyses indicated that the di-tert-butyl phenol-based dual inhibitors reduce the expression of COX-2, 5-LOX, and CD44v6 in human colon cancer HCA-7 cells, while the combination of CD44v6shRNA and DTPSAL has an additional inhibitory effect on CD44v6 mRNA expression. The synergistic inhibitory effect of Celecoxib and Licofelone on CD44v6 mRNA expression suggests that the present dual inhibitors down-regulate cyclooxygenase and lipoxygenase enzymes through CD44v6. The compounds also exhibited enhanced antiproliferative potency compared to standard dual COX/LOX inhibitor, viz. Licofelone. Importantly, the HA/CD44v6 antagonist CD44v6shRNA in combination with synthetic compounds had a sensitizing effect on the cancer cells which enhanced their antiproliferative potency, a finding which is crucial for the anti-proliferative potency of the novel synthetic di-tert-butyl phenol based dual COX-LOX inhibitors in colon cancer cells.

  19. Novel di-tertiary-butyl phenylhydrazones as dual cyclooxygenase-2/5-lipoxygenase inhibitors: synthesis, COX/LOX inhibition, molecular modeling, and insights into their cytotoxicities.

    PubMed

    Ghatak, Shibnath; Vyas, Alok; Misra, Suniti; O'Brien, Paul; Zambre, Ajit; Fresco, Victor M; Markwald, Roger R; Swamy, K Venkateshwara; Afrasiabi, Zahra; Choudhury, Amitava; Khetmalas, Madhukar; Padhye, Subhash

    2014-01-01

    Although dual inhibition of Cyclooxygenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) enzymes is highly effective than targeting COX or LOX alone, there are only a few reports of examining such compounds in case of colorectal cancers (CRC). In the present work we report that the novel di-tert-butyl phenol-based dual inhibitors DTPSAL, DTPBHZ, DTPINH, and DTPNHZ exhibit significant cytotoxicity against human CRC cell lines. Molecular docking studies revealed a good fit of these compounds in the COX-2 and 5-LOX protein cavities. The inhibitors show significant inhibition of COX-2 and 5-LOX activities and are effective against a panel of human colon cancer cell lines including HCA-7, HT-29, SW480 and intestinal Apc10.1 cells as well as the hyaluronan synthase-2 (Has2) enzyme over-expressing colon cancer cells, through inhibition of the Hyaluronan/CD44v6 cell survival pathway. Western blot analysis and qRT-PCR analyses indicated that the di-tert-butyl phenol-based dual inhibitors reduce the expression of COX-2, 5-LOX, and CD44v6 in human colon cancer HCA-7 cells, while the combination of CD44v6shRNA and DTPSAL has an additional inhibitory effect on CD44v6 mRNA expression. The synergistic inhibitory effect of Celecoxib and Licofelone on CD44v6 mRNA expression suggests that the present dual inhibitors down-regulate cyclooxygenase and lipoxygenase enzymes through CD44v6. The compounds also exhibited enhanced antiproliferative potency compared to standard dual COX/LOX inhibitor, viz. Licofelone. Importantly, the HA/CD44v6 antagonist CD44v6shRNA in combination with synthetic compounds had a sensitizing effect on the cancer cells which enhanced their antiproliferative potency, a finding which is crucial for the anti-proliferative potency of the novel synthetic di-tert-butyl phenol based dual COX-LOX inhibitors in colon cancer cells. PMID:24295787

  20. 5-Lipoxygenase Negatively Regulates Th1 Response during Brucella abortus Infection in Mice

    PubMed Central

    Fahel, Júlia Silveira; de Souza, Mariana Bueno; Gomes, Marco Túlio Ribeiro; Corsetti, Patricia P.; Carvalho, Natalia B.; Marinho, Fabio A. V.; de Almeida, Leonardo A.; Caliari, Marcelo V.; Machado, Fabiana Simão

    2015-01-01

    Brucella abortus is a Gram-negative bacterium that infects humans and cattle, causing a chronic inflammatory disease known as brucellosis. A Th1-mediated immune response plays a critical role in host control of this pathogen. Recent findings indicate contrasting roles for lipid mediators in host responses against infections. 5-Lipoxygenase (5-LO) is an enzyme required for the production of the lipid mediators leukotrienes and lipoxins. To determine the involvement of 5-LO in host responses to B. abortus infection, we intraperitoneally infected wild-type and 5-LO-deficient mice and evaluated the progression of infection and concomitant expression of immune mediators. Here, we demonstrate that B. abortus induced the upregulation of 5-LO mRNA in wild-type mice. Moreover, this pathogen upregulated the production of the lipid mediators leukotriene B4 and lipoxin A4 in a 5-LO-dependent manner. 5-LO-deficient mice displayed lower bacterial burdens in the spleen and liver and less severe liver pathology, demonstrating an enhanced resistance to infection. Host resistance paralleled an increased expression of the proinflammatory mediators interleukin-12 (IL-12), gamma interferon (IFN-γ), and inducible nitric oxide synthase (iNOS) during the course of infection. Moreover, we demonstrated that 5-LO downregulated the expression of IL-12 in macrophages during B. abortus infection. Our results suggest that 5-LO has a major involvement in B. abortus infection, by functioning as a negative regulator of the protective Th1 immune responses against this pathogen. PMID:25583526

  1. Chronic adventitial inflammation, vasa vasorum expansion, and 5-lipoxygenase up-regulation in irradiated arteries from cancer survivors

    PubMed Central

    Halle, Martin; Christersdottir, Tinna; Bäck, Magnus

    2016-01-01

    Radiation-induced cardiovascular disease is an emerging problem in a steadily increasing population of survivors of cancer. However, the underlying biology is poorly described, and the late onset, which occurs several years after exposure, precludes adequate investigations in animal and cell culture models. We investigated the role of the 5-lipoxygenase (5-LO)/leukotriene pathway in radiation-induced vascular changes. Use of paired samples of irradiated arteries and nonirradiated internal control arteries from the same patient that were harvested during surgery for cancer reconstruction ≤10 yr after radiotherapy provides a unique human model of chronic radiation–induced vascular changes. Immunohistochemical stainings and perioperative inspection revealed an adventitial inflammatory response, with vasa vasorum expansion and chronic infiltration of CD68+ macrophages. These macrophages stained positive for the leukotriene-forming enzyme 5-LO. Messenger RNA levels of 5-LO and leukotriene B4 receptor 1 were increased in irradiated arterial segments compared with control vessels. These results point to targeting the 5-LO/leukotriene pathway as a therapeutic adjunct to prevent late adverse vascular effects of radiotherapy.—Halle, M., Christersdottir, T., Bäck, M. Chronic adventitial inflammation, vasa vasorum expansion, and 5-lipoxygenase up-regulation in irradiated arteries from cancer survivors. PMID:27530979

  2. The selective 5-lipoxygenase inhibitor, A63162 reduces PC3 proliferation and initiates morphologic changes consistent with secretion.

    SciTech Connect

    Anderson, K. M.; Seed, T.; Ondrey, F.; Harris, J. E.; Center for Mechanistic Biology and Biotechnology; Rush Medical Coll.; Univ. of Minnesota

    1994-09-01

    We examined the effect of A63162 (Abbott), a selective inhibitor of 5-lipoxygenase on human prostate (PC3) cell proliferation. Within 5 min DNA synthesis was reversibly inhibited by 40 {micro}M A63162, without altered cellular attachment or uptake of trypan blue. After 72 Hr, cells continues to be attached and exclude dye, were reduced in number and their histology was altered. Many treated cells were larger, more pleomorphic, with nuclear and cytoplasmic ultrastructural changes consistent with preparation for secretion. Some cells contained moderately swollen, distorted mitochondria. ETYA, a less selective inhibitor of 5-lipoxygenase that also inhibits cell replication, acutely reduced O2 uptake by 40%, but A63162 did not. The retention of the supravital mitochondrial dye, rhodamine 123 was increased by ETYA at 4 hr, but not after 24 hr; retention was not altered by A63162. Although the mechanism by which A63162 reversibly inhibits PC3 proliferation and initiates preparation for secretion is not identified, additional studies should further define its role in these events

  3. Chemoprevention of 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster cheek pouch carcinogenesis by a 5-lipoxygenase inhibitor, garcinol.

    PubMed

    Chen, Xin; Zhang, Xinyan; Lu, Ye; Shim, Joong-Youn; Sang, Shengmin; Sun, Zheng; Chen, Xiaoxin

    2012-01-01

    Our previous studies have shown that aberrant arachidonic acid metabolism, especially the 5-lipoxygenase (5-Lox) pathway, is involved in oral carcinogenesis and can be targeted for cancer prevention. To develop potent topical agents for oral cancer chemoprevention, 5 known 5-Lox inhibitors from dietary and synthetic sources (Zileuton, ABT-761, licofelone, curcumin, and garcinol) were evaluated in silico for their potential efficacy. Garcinol, a polyisoprenylated benzophenone from the fruit rind of Garcinia spp., was found to be a promising agent based on the calculation of a theoretical activity index. Computer modeling showed that garcinol well fit the active site of 5-Lox, and potentially inhibited enzyme activity through interactions between the phenolic hydroxyl groups and the non-heme catalytic iron. In a short-term study on 7,12-dimethylbenz[a]anthracene (DMBA)-treated hamster cheek pouch, topical garcinol suppressed leukotriene B4 (LTB4) biosynthesis and inhibited inflammation and cell proliferation in the oral epithelium. In a long-term carcinogenesis study, topical garcinol significantly reduced the size of visible tumors, the number of cancer lesions, cell proliferation, and LTB4 biosynthesis. These results demonstrated that topical application of a 5-Lox inhibitor, garcinol, had chemopreventive effect on DMBA-induced hamster cheek pouch carcinogenesis. PMID:23137051

  4. Possible role for interactions between 5-lipoxygenase (5-LOX) and AMPA GluR1 receptors in depression and in antidepressant therapy

    PubMed Central

    Manev, Radmila; Mrazovac, Danijela; Manev, Hari

    2009-01-01

    Summary Emerging evidence suggests that 5-lipoxygenase (5-LOX) plays a role in central nervous system functioning. It has been shown that 5-LOX metabolic products can decrease the phosphorylation of the glutamate reseptor subunit GluR1, and that this effect can be antagonized by 5-LOX inhibitors. Recent concepts about the pathobiological mechanisms of depression and the molecular mechanisms of antidepressant activity postulate a significant role for glutamatergic neurotransmission and the GluR1 receptor. Regulation of GluR1 phosphorylation, i.e., enhancement of this phosphorylation, may be a part of antidepressant activity. On the other hand, reduced GluR1 phosphorylation may be a pathobiological mechanism contributing to depression. Since 5-LOX inhibitors, along with antidepressants share the capacity to increase GluR1 phosphorylation, we hypothesize that they may also have antidepressant properties. Furthermore, we postulate that increased brain 5-LOX expression may lead to decreased GluR1 phosphorylation and favor the development of depression. For example, brain 5-LOX expression is stimulated by stress hormone glucocorticoids, and stress is a known as a contributing factor to depression. PMID:17449191

  5. Modulation of LPS-induced memory insult, γ-secretase and neuroinflammation in 3xTg mice by 5-Lipoxygenase

    PubMed Central

    Joshi, Yash B.; Giannopoulos, Phillip F.; Chu, Jin; Praticò, Domenico

    2014-01-01

    Besides amyloid and tau pathology, a constant feature of Alzheimer’s disease (AD) is an intense inflammatory response, which is considered an active player in its pathogenesis. The 5-Lipoxygenase (5LO) is a proinflammatory enzyme and an endogenous modulator of AD-like phenotype in mouse models of the disease. To further understand the role of 5LO in AD pathogenesis, we exposed the 3xTg and 3xTg/5LO knockout mice to lipopolysaccharide (LPS), a known inducer of neuroinflammation, and evaluated its effect on their AD-like phenotype. 3xTg mice treated with LPS manifested a worsening of behavior, γ-secretase up-regulation, and increased neuroinflammatory responses. These effects were completely prevented in 3xTg mice genetically deficient for 5LO. By contrast, the absence of 5LO did not protect against increase in tau phosphorylation at specific epitopes that were mediated by the activation of the cyclin-dependent kinase 5. Our data demonstrate that the 5LO pathway affects key neuropathological features of the AD-like phenotype (behavior, Abeta, microgliosis, astrocytosis) but not others (tau pathology) in the LPS-dependent neuroinflammation model. The opposite ways whereby 5LO influences the LPS-dependent effects in vivo supports the complex nature of the neuroinflammatory response in AD and its differential role in modulating amyloid and tau neuropathology. PMID:24332986

  6. Systems Pharmacology Models Can Be Used to Understand Complex Pharmacokinetic-Pharmacodynamic Behavior: An Example Using 5-Lipoxygenase Inhibitors

    PubMed Central

    Demin, O; Karelina, T; Svetlichniy, D; Metelkin, E; Speshilov, G; Demin Jr, O; Fairman, D; van der Graaf, P H; Agoram, B M

    2013-01-01

    Zileuton, a 5-lipoxygenase (5LO) inhibitor, displays complex pharmaokinetic (PK)-pharmacodynamic (PD) behavior. Available clinical data indicate a lack of dose–bronchodilatory response during initial treatment, with a dose response developing after ~1–2 weeks. We developed a quantitative systems pharmacology (QSP) model to understand the mechanism behind this phenomenon. The model described the release, maturation, and trafficking of eosinophils into the airways, leukotriene synthesis by the 5LO enzyme, leukotriene signaling and bronchodilation, and the PK of zileuton. The model provided a plausible explanation for the two-phase bronchodilatory effect of zileuton–the short-term bronchodilation was due to leukotriene inhibition and the long-term bronchodilation was due to inflammatory cell infiltration blockade. The model also indicated that the theoretical maximum bronchodilation of both 5LO inhibition and leukotriene receptor blockade is likely similar. QSP modeling provided interesting insights into the effects of leukotriene modulation. PMID:24026253

  7. Structural insights into human 5-lipoxygenase inhibition: combined ligand-based and target-based approach.

    PubMed

    Charlier, Caroline; Hénichart, Jean-Pierre; Durant, François; Wouters, Johan

    2006-01-12

    The human 5-LOX enzyme and its interaction with competitive inhibitors were investigated by means of a combined ligand-based and target-based approach. First, a pharmacophore model was generated for 16 non redox 5-LOX inhibitors with Catalyst (HipHop module). It includes two hydrophobic groups, an aromatic ring, and two hydrogen bond acceptors. The 3D structure of human 5-LOX was then modeled based on the crystal structure of rabbit 15-LOX, and the binding modes of representative ligands were studied by molecular docking. Confrontation of the docking results with the pharmacophore model allowed the weighting of the pharmacophoric features and the integration of structural information. This led to the proposal of an interaction model inside the 5-LOX active site, consisting of four major and two secondary interaction points: on one hand, two hydrophobic groups, an aromatic ring, and a hydrogen bond acceptor, and, on the other hand, an acidic moiety and an additional hydrogen bond acceptor. PMID:16392803

  8. Structural insights into human 5-lipoxygenase inhibition: combined ligand-based and target-based approach.

    PubMed

    Charlier, Caroline; Hénichart, Jean-Pierre; Durant, François; Wouters, Johan

    2006-01-12

    The human 5-LOX enzyme and its interaction with competitive inhibitors were investigated by means of a combined ligand-based and target-based approach. First, a pharmacophore model was generated for 16 non redox 5-LOX inhibitors with Catalyst (HipHop module). It includes two hydrophobic groups, an aromatic ring, and two hydrogen bond acceptors. The 3D structure of human 5-LOX was then modeled based on the crystal structure of rabbit 15-LOX, and the binding modes of representative ligands were studied by molecular docking. Confrontation of the docking results with the pharmacophore model allowed the weighting of the pharmacophoric features and the integration of structural information. This led to the proposal of an interaction model inside the 5-LOX active site, consisting of four major and two secondary interaction points: on one hand, two hydrophobic groups, an aromatic ring, and a hydrogen bond acceptor, and, on the other hand, an acidic moiety and an additional hydrogen bond acceptor.

  9. Synthesis and biological evaluation of novel myrtucommulones and structural analogues that target mPGES-1 and 5-lipoxygenase.

    PubMed

    Wiechmann, Katja; Müller, Hans; Huch, Volker; Hartmann, David; Werz, Oliver; Jauch, Johann

    2015-08-28

    The natural acylphloroglucinol myrtucommulone A (1) inhibits microsomal prostaglandin E2 synthase (mPGES)-1 and 5-lipoxygenase (5-LO), and induces apoptosis of cancer cells. Starting from 1 as lead, 28 analogues were synthesized following a straightforward modular strategy with high yielding convergent steps. Major structural variations concerned (I) replacement of the syncarpic acid moieties by dimedone or indandione, (II) cyclization of the syncarpic acid with the acylphloroglucinol core, and (III) substitution of the methine bridges and the acyl residue with isopropyl, isobutyl, n-pentyl or phenyl groups, each. The potency for mPGES-1 inhibition was improved by 12.5-fold for 43 (2-(1-(3-hexanoyl-2,4,6-trihydroxy-5-(1-(3-hydroxy-1-oxo-1H-inden-2-yl)-2-methylpropyl)phenyl)-2-methylpropyl)-3-hydroxy-1H-inden-1-one) with IC50 = 0.08 μM, and 5-LO inhibition was improved 33-fold by 47 (2-((3-hexanoyl-2,4,6-trihydroxy-5-((3-hydroxy-1-oxo-1H-inden-2-yl) (phenyl)methyl)phenyl) (phenyl)methyl)-3-hydroxy-1H-inden-1-one) with IC50 = 0.46 μM. SAR studies revealed divergent structural determinants for induction of cell death and mPGES-1/5-LO inhibition, revealing 43 and 47 as non-cytotoxic mPGES-1 and 5-LO inhibitors that warrant further preclinical assessment as anti-inflammatory drugs. PMID:26123643

  10. Deletion of 5-Lipoxygenase in the Tumor Microenvironment Promotes Lung Cancer Progression and Metastasis through Regulating T Cell Recruitment

    PubMed Central

    Poczobutt, Joanna M.; Nguyen, Teresa T.; Hanson, Dwight; Li, Howard; Sippel, Trisha R.; Weiser-Evans, Mary C. M.; Gijon, Miguel; Murphy, Robert C.

    2016-01-01

    Eicosanoids, including PGs, produced by cyclooxygenases (COX), and leukotrienes, produced by 5-lipoxygenase (5-LO) have been implicated in cancer progression. These molecules are produced by both cancer cells and the tumor microenvironment (TME). We previously reported that both COX and 5-LO metabolites increase during progression in an orthotopic immunocompetent model of lung cancer. Although PGs in the TME have been well studied, less is known regarding 5-LO products produced by the TME. We examined the role of 5-LO in the TME using a model in which Lewis lung carcinoma cells are directly implanted into the lungs of syngeneic WT mice or mice globally deficient in 5-LO (5-LO-KO). Unexpectedly, primary tumor volume and liver metastases were increased in 5-LO-KO mice. This was associated with an ablation of leukotriene (LT) production, consistent with production mainly mediated by the microenvironment. Increased tumor progression was partially reproduced in global LTC4 synthase KO or mice transplanted with LTA4 hydrolase-deficient bone marrow. Tumor-bearing lungs of 5-LO-KO had decreased numbers of CD4 and CD8 T cells compared with WT controls, as well as fewer dendritic cells. This was associated with lower levels of CCL20 and CXL9, which have been implicated in dendritic and T cell recruitment. Depletion of CD8 cells increased tumor growth and eliminated the differences between WT and 5-LO mice. These data reveal an antitumorigenic role for 5-LO products in the microenvironment during lung cancer progression through regulation of T cells and suggest that caution should be used in targeting this pathway in lung cancer. PMID:26663781

  11. The metabolic effects of inhibitors of 5-lipoxygenase and of cyclooxygenase 1 and 2 are an advancement in the efficacy and safety of anti-inflammatory therapy.

    PubMed

    Celotti, Fabio; Durand, Thierry

    2003-07-01

    Chronic treatment of inflammatory diseases with non-steroidal anti-inflammatory drugs is effective but not always devoid of serious side effects. In particular, the use of traditional non-steroidal aspirin-like drugs has been associated with a high incidence of gastrointestinal bleedings. The development of a new class of drugs, the selective cyclooxygenase type 2 (COX-2) inhibitors, has generated much expectation on the possibility to have safer compounds. After the initial enthusiasm of the scientific community, a re-evaluation of some large, randomized double-blind clinical studies performed with two of these compounds, has disclosed that the late serious gastrointestinal complications are not significantly reduced in comparison with non-selective inhibitors and that cardiovascular concerns might arise particularly if theses drugs are utilized in patients with underlying heart diseases. A new promising class of drugs to control inflammatory diseases is in advanced clinical development. The balanced inhibitors of 5-lipoxygenase (5-LOX) and of cyclooxygenase (both types 1 and 2) block the formation of all the enzymatically arachidonic acid-derived metabolites, both prostaglandins (like COX inhibitors) and leukotrienes (LT); these drugs have been shown to possess a very good anti-inflammatory efficacy without serious side effects. Licofelone, previously known as ML3000, is the molecule in the most advanced phase of clinical development (phase III) among this class of compounds; it is a potent, competitive, and well balanced inhibitor of 5-LOX and COX pathways. The drug has been shown to possess analgesic, anti-inflammatory, antipyretic antibronchocostrictory and antiplatelet properties at doses which are safe for the gastrointestinal tract. Moreover, the newly performed preclinical studies, here briefly reviewed, appear to indicate that the compound seems particularly suitable to protect the articular cartilage and the synovial space in degenerative joint disease

  12. Morphologic changes of apoptosis induced in human chronic myelogenous leukemia "blast" cells by SC41661A (SEARLE), a selective inhibitor of 5-Lipoxygenase.

    SciTech Connect

    Anderson, K. M.; Seed, T. M.; Jajeh, A.; Jia, P.; Harris, J. E.; Center for Mechanistic Biology and Biotechnology; Rush Medical Coll.; Cook County Hospital

    1994-01-01

    Several inhibitors of the arachidonic acid-metabolizing enzyme, 5-lipoxygenase reduce proliferation of hematopoietic and non-hematopoietic cells and cell lines and some cells undergo limited differentiation. Cells were cultured from patients with chronic myelogenous leukemia in 'blast' crisis with the selective inhibitor of 5-lipoxygenase, SC41661A[3-(3,5-bis(1,1-dimethyl)-4-hydroxyphenyl)hiol]-N-me thyl-N-[2-(2- phridinyl-propanamide)]. Cells cultured for 3 to 5 days with 40 {micro}M SC41661A exhibited reduced cellular numbers along with ultrastructural changes and DNA laddering characteristic of apoptosis. Similar culture conditions reduced proliferation of U937 monoblastoid cells. In U937 cells, the ultrastructural features of apoptosis were not observed at 72 hours, when DNA laddering was present and cell numbers were reduced, but was present after 144 hours of culture. Dissociation between certain morphologic and biochemical sequelae of apoptosis has been described in other systems. These observations are of interest since the induction of apoptosis in dividing chronic myelogenous leukemia (CML) cells by a non-cytotoxic agent suggests paradigmatically new sites for therapeutic intervention.

  13. Molecular cloning and functional characterization of arachidonate 5-lipoxygenase (Alox5), and its expression in response to the ratio of linolenic acid to linoleic acid in diets of large yellow croaker (Larmichthys crocea).

    PubMed

    Wang, Tianjiao; Zuo, Rantao; Mai, Kangsen; Xu, Wei; Ai, Qinghui

    2016-11-01

    This study was conducted to clone and functionally characterize a full-length cDNA encoding arachidonate 5-lipoxygenase (Alox5) from large yellow croaker (Larmichthys crocea) and investigate its gene expression in response to graded dietary ratio of linolenic acid (ALA) to linoleic acid (LNA) (0.03, 0.06, 0.45, 0.90 and 1.51). An isolated 2372bp cDNA clone of Alox5 contained an open reading frame spanning 2025bp encoding a protein with the ability to modify arachidonate acid (AA) to 5-hydroxyeicosatetraenoic (5-HETE). In the liver, the Alox5 mRNA expression levels significantly increased to the maximum when the dietary ALA/LNA increased from 0.03 to 0.06, and then significantly decreased with dietary ALA/LNA increased to 1.51 (P<0.05). In the kidney, the expression levels of Alox5 of fish fed diets with low dietary ALA/LNA (0.03-0.06) were significantly higher than those of fish fed diets with high dietary ALA/LNA (0.45-1.51) (P<0.05). The dual-luciferase reporter assays showed that the nuclear factor kappa B (NF-κB) could act on cognate cis-acting elements in the promoter of Alox5 and increased the transcription of Alox5. Results of the present study suggested that the expression of Alox5 is higher in croakers fed high concentrations of LNA compared to those fed high concentrations of ALA, which might be regulated by NF-κB and contribute to the inflammation process by catalyzing the dioxygenation of AA. PMID:27378407

  14. Molecular cloning and functional characterization of arachidonate 5-lipoxygenase (Alox5), and its expression in response to the ratio of linolenic acid to linoleic acid in diets of large yellow croaker (Larmichthys crocea).

    PubMed

    Wang, Tianjiao; Zuo, Rantao; Mai, Kangsen; Xu, Wei; Ai, Qinghui

    2016-11-01

    This study was conducted to clone and functionally characterize a full-length cDNA encoding arachidonate 5-lipoxygenase (Alox5) from large yellow croaker (Larmichthys crocea) and investigate its gene expression in response to graded dietary ratio of linolenic acid (ALA) to linoleic acid (LNA) (0.03, 0.06, 0.45, 0.90 and 1.51). An isolated 2372bp cDNA clone of Alox5 contained an open reading frame spanning 2025bp encoding a protein with the ability to modify arachidonate acid (AA) to 5-hydroxyeicosatetraenoic (5-HETE). In the liver, the Alox5 mRNA expression levels significantly increased to the maximum when the dietary ALA/LNA increased from 0.03 to 0.06, and then significantly decreased with dietary ALA/LNA increased to 1.51 (P<0.05). In the kidney, the expression levels of Alox5 of fish fed diets with low dietary ALA/LNA (0.03-0.06) were significantly higher than those of fish fed diets with high dietary ALA/LNA (0.45-1.51) (P<0.05). The dual-luciferase reporter assays showed that the nuclear factor kappa B (NF-κB) could act on cognate cis-acting elements in the promoter of Alox5 and increased the transcription of Alox5. Results of the present study suggested that the expression of Alox5 is higher in croakers fed high concentrations of LNA compared to those fed high concentrations of ALA, which might be regulated by NF-κB and contribute to the inflammation process by catalyzing the dioxygenation of AA.

  15. Gene Knockout of 5-Lipoxygenase Rescues Synaptic Dysfunction and Improves Memory in the Triple-Transgenic Model of Alzheimer’s Disease

    PubMed Central

    Giannopoulos, Phillip F.; Chu, Jin; Joshi, Yash B.; Sperow, Margaret; Li, Jin-Luo; Kirby, Lynn G.; Praticò, Domenico

    2013-01-01

    The 5-Lipoxygenase (5LO) is upregulated in Alzheimer’s disease (AD), and in vivo modulates the amyloidotic phenotype of APP transgenic mice. However, no data are available on the effects that 5LO has on synaptic function, integrity and cognition. To address this issue we used a genetic and a pharmacologic approach by generating 3xTg mice deficient for 5LO, and administering 3xTg mice which a 5LO inhibitor. Compared with controls, we found that even before the development of overt neuropathology, both animals manifested significant memory improvement, rescue of their synaptic dysfunction and amelioration of synaptic integrity. In addition, later in life these mice had a significant reduction of Aβ and tau pathology. Our findings support a novel functional role for 5LO in regulating synaptic plasticity and memory. They establish this proetin as a pleiotropic contributor to the development of the full spectrum of the AD phenotype, making it a valid therapeutic target for the treatment of AD. PMID:23478745

  16. Separating proteins with activated carbon.

    PubMed

    Stone, Matthew T; Kozlov, Mikhail

    2014-07-15

    Activated carbon is applied to separate proteins based on differences in their size and effective charge. Three guidelines are suggested for the efficient separation of proteins with activated carbon. (1) Activated carbon can be used to efficiently remove smaller proteinaceous impurities from larger proteins. (2) Smaller proteinaceous impurities are most efficiently removed at a solution pH close to the impurity's isoelectric point, where they have a minimal effective charge. (3) The most efficient recovery of a small protein from activated carbon occurs at a solution pH further away from the protein's isoelectric point, where it is strongly charged. Studies measuring the binding capacities of individual polymers and proteins were used to develop these three guidelines, and they were then applied to the separation of several different protein mixtures. The ability of activated carbon to separate proteins was demonstrated to be broadly applicable with three different types of activated carbon by both static treatment and by flowing through a packed column of activated carbon. PMID:24898563

  17. Modulation of coronary flow rate and cardiac contractility by the divalent cation ionophore A23187 and inhibitors of the cyclooxygenase and 5-lipoxygenase pathways: development of heterogeneous patterns of myocardial ischemia.

    PubMed

    Björnsson, O G; Kobayashi, K; Williamson, J R

    1988-02-01

    In the present studies, we demonstrate in buffer-perfused isolated working guinea pig hearts that indometacin reduces coronary flow rate in a dose-dependent manner (max 56.7 +/- 5.5%, SEM, n = 6, of control at 5 x 10(-6) mol/l of indometacin, P less than 0.01), and that this leads to a development of heterogeneous patterns of myocardial ischemia (elevated myocardial levels of reduced pyridine nucleotide, NADH) and depressed cardiac work (64.7 +/- 11.7%, SEM, of control at 5 x 10(-6) mol/l of indometacin, P less than 0.05). The effect of indometacin on coronary flow rate and consequently on myocardial tissue oxygenation was completely prevented by the preferential 5-lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) (1 x 10(-6) mol/l), or the sulfidopeptide leukotriene receptor antagonist FPL 55712 (2 x 10(-5) mol/l), indicating that the isolated working guinea pig heart, even when deprived of blood, is able to produce vasoactive sulfidopeptide leukotrienes at significant levels. At higher concentrations of indometacin (5 x 10(-5) mol/l, 1 x 10(-4) mol/l), coronary flow rate returned to initial levels while cardiac work became further depressed despite normoxic levels of NADH. These data support that indometacin also has a direct suppressive effect on the myocardium independent of its coronary vascular effect. This conclusion is supported by the observation that addition of sodium arachidonate (6 x 10(-5) mol/l) completely inhibited the vascular effect of indometacin, but not the depressive effect on the myocardium. The divalent cation ionophore A23187 (6 x 10(-6) mol/l) had a strong positive chronotropic effect on the heart and a biphasic effect on coronary flow rate. After a brief period of increased coronary flow rate, presumably due to coronary vasodilatation, the ionophore caused a sustained reduction in coronary flow, and this was accompanied by high myocardial levels of NADH fluorescence of characteristically heterogeneous pattern. This is presumably

  18. Western blot expression of 5-lipoxygenase in the brain from striped dolphins (stenella coeruleoalba) and bottlenose dolphins (tursiops truncatus) with or without encephalitis/meningo-encephalitis of infectious nature.

    PubMed

    Di Guardo, G; Falconi, A; Di Francesco, A; Mazzariol, S; Centelleghe, C; Casalone, C; Pautasso, A; Cocumelli, C; Eleni, C; Petrella, A; Di Francesco, C E; Sabatucci, A; Leonardi, L; Serroni, A; Marsili, L; Storelli, M M; Giacominelli-Stuffler, R

    2015-01-01

    Dolphin Morbillivirus (DMV), Toxoplasma gondii and Brucella ceti are pathogens of major concern for wild cetaceans. Although a more or less severe encephalitis/meningo-encephalitis may occur in striped dolphins (Stenella coeruleoalba) and bottlenose dolphins (Tursiops truncatus) infected by the aforementioned agents, almost no information is available on the neuropathogenesis of brain lesions, including the neuronal and non-neuronal cells targeted during infection, along with the mechanisms underlying neurodegeneration. We analyzed 5-lipoxygenase (5-LOX) expression in the brain of 11 striped dolphins and 5 bottlenose dolphins, affected or not by encephalitic lesions of various degrees associated with DMV, T. gondii and B. ceti. All the 8 striped dolphins with encephalitis showed a more consistent 5-LOX expression than that observed in the 3 striped dolphins showing no morphologic evidence of brain lesions, with the most prominent band intensity being detected in a B. ceti-infected animal. Similar results were not obtained in T. gondii-infected vs T. gondii-uninfected bottlenose dolphins. Overall, the higher 5-LOX expression found in the brain of the 8 striped dolphins with infectious neuroinflammation is of interest, given that 5-LOX is a putative marker for neurodegeneration in human patients and in experimental animal models. Therefore, further investigation on this challenging issue is also needed in stranded cetaceans affected by central neuropathies.

  19. Western blot expression of 5-lipoxygenase in the brain from striped dolphins (stenella coeruleoalba) and bottlenose dolphins (tursiops truncatus) with or without encephalitis/meningo-encephalitis of infectious nature.

    PubMed

    Di Guardo, G; Falconi, A; Di Francesco, A; Mazzariol, S; Centelleghe, C; Casalone, C; Pautasso, A; Cocumelli, C; Eleni, C; Petrella, A; Di Francesco, C E; Sabatucci, A; Leonardi, L; Serroni, A; Marsili, L; Storelli, M M; Giacominelli-Stuffler, R

    2015-01-01

    Dolphin Morbillivirus (DMV), Toxoplasma gondii and Brucella ceti are pathogens of major concern for wild cetaceans. Although a more or less severe encephalitis/meningo-encephalitis may occur in striped dolphins (Stenella coeruleoalba) and bottlenose dolphins (Tursiops truncatus) infected by the aforementioned agents, almost no information is available on the neuropathogenesis of brain lesions, including the neuronal and non-neuronal cells targeted during infection, along with the mechanisms underlying neurodegeneration. We analyzed 5-lipoxygenase (5-LOX) expression in the brain of 11 striped dolphins and 5 bottlenose dolphins, affected or not by encephalitic lesions of various degrees associated with DMV, T. gondii and B. ceti. All the 8 striped dolphins with encephalitis showed a more consistent 5-LOX expression than that observed in the 3 striped dolphins showing no morphologic evidence of brain lesions, with the most prominent band intensity being detected in a B. ceti-infected animal. Similar results were not obtained in T. gondii-infected vs T. gondii-uninfected bottlenose dolphins. Overall, the higher 5-LOX expression found in the brain of the 8 striped dolphins with infectious neuroinflammation is of interest, given that 5-LOX is a putative marker for neurodegeneration in human patients and in experimental animal models. Therefore, further investigation on this challenging issue is also needed in stranded cetaceans affected by central neuropathies. PMID:25864766

  20. Roles of 5-lipoxygenase and cysteinyl-leukotriene type 1 receptors in the hematological response to allergen challenge and its prevention by diethylcarbamazine in a murine model of asthma.

    PubMed

    Masid-de-Brito, Daniela; Queto, Túlio; Gaspar-Elsas, Maria Ignez C; Xavier-Elsas, Pedro

    2014-01-01

    Diethylcarbamazine (DEC), which blocks leukotriene production, abolishes the challenge-induced increase in eosinopoiesis in bone-marrow from ovalbumin- (OVA-) sensitized mice, suggesting that 5-lipoxygenase (5-LO) products contribute to the hematological responses in experimental asthma models. We explored the relationship between 5-LO, central and peripheral eosinophilia, and effectiveness of DEC, using PAS or BALB/c mice and 5-LO-deficient mutants. We quantified eosinophil numbers in freshly harvested or cultured bone-marrow, peritoneal lavage fluid, and spleen, with or without administration of leukotriene generation inhibitors (DEC and MK886) and cisteinyl-leukotriene type I receptor antagonist (montelukast). The increase in eosinophil numbers in bone-marrow, observed in sensitized/challenged wild-type mice, was abolished by MK886 and DEC pretreatment. In ALOX mutants, by contrast, there was no increase in bone-marrow eosinophil counts, nor in eosinophil production in culture, in response to sensitization/challenge. In sensitized/challenged ALOX mice, challenge-induced migration of eosinophils to the peritoneal cavity was significantly reduced relative to the wild-type PAS controls. DEC was ineffective in ALOX mice, as expected from a mechanism of action dependent on 5-LO. In BALB/c mice, challenge significantly increased spleen eosinophil numbers and DEC treatment prevented this increase. Overall, 5-LO appears as indispensable to the systemic hematological response to allergen challenge, as well as to the effectiveness of DEC. PMID:25477712

  1. Allostery in BAX protein activation.

    PubMed

    Jiang, Zhenyan; Zhang, Hansi; Böckmann, Rainer A

    2016-11-01

    BAX is a member of the proapoptotic BCL-2 family of proteins, which is involved in the regulation of the intrinsic pathway of apoptosis. In the process of apoptosis, BH3-only molecules activate cytosolic BAX. Activated BAX molecules insert into the mitochondrial outer membrane with their [Formula: see text]-helix and form oligomers that lead to membrane poration, resulting in the release of apoptogenic factors including cytochrome c. Recently, a novel interaction site for the binding of the BIM SAHB ligand to BAX was reported. BIM SAHB binding was shown to invoke the exposure of the 6A7 epitope (amino acids 13-19) and of the BH3 domain of BAX, followed by mobilization of the BAX [Formula: see text]-helix. However, the intramolecular pathway for signal transmission in BAX, from BIM SAHB binding to mobilization of the [Formula: see text]-helix largely remained elusive. For a molecular understanding of the activation of BAX, and thus the first steps in apoptosis, we performed microsecond atomistic molecular dynamics simulations both of the BAX protein and of the BAX:BIM SAHB complex in aqueous solution. In agreement with experiment, the 6A7 and BH3 domains adopt a more solvent-exposed conformation within the BAX:BIM SAHB complex. BIM SAHB binding was found to stabilize the secondary structure of the [Formula: see text]9-helix. A force distribution analysis revealed a force network of residue-residue interactions responsible for signal transmission from the BIM SAHB binding site predominantly via the [Formula: see text]4- and [Formula: see text]6-helices to the [Formula: see text]9-helix on the opposite site of the protein.

  2. Fuscoside: an anti-inflammatory marine natural product which selectively inhibits 5-lipoxygenase. Part I: Physiological and biochemical studies in murine inflammatory models.

    PubMed

    Jacobson, P B; Jacobs, R S

    1992-08-01

    The biological and biochemical pharmacology of fuscoside, a novel anti-inflammatory marine natural product isolated from the Caribbean gorgonian Eunicea fusca, has recently been characterized using murine (part I) and human (part II) models of inflammation. Topically applied fuscoside (FSD) effectively inhibits phorbol myristate acetate (PMA)-induced edema in mouse ears at levels comparable with indomethacin over a 3.3-hr exposure period, and is significantly more efficacious than indomethacin over 24 hr in the PMA model. Histological preparations and quantification of the neutrophil-specific marker, myeloperoxidase, demonstrate that FSD inhibits neutrophil infiltration into PMA-induced regions of edema and inflammation. In systemic studies, where FSD is injected i.p. before the topical application of PMA, negligible effects on ear inflammation are observed. FSD does not inhibit bee venom or human synovial fluid phospholipase A2 up to concentrations of 500 microM. In calcium ionophore-activated cultures of mouse peritoneal macrophages, FSD selectively and irreversibly inhibits leukotriene C4 biosynthesis (IC50 = 8 microM), yet has negligible effects on prostaglandin E2 production. FSD is also without effect on the conversion of arachidonic acid to prostaglandin E2 by ram seminal vesicle cyclooxygenase. Chromatographic and spectroscopic studies suggest that FSD is not metabolized, and that drug uptake/binding by macrophages is time dependent, saturable and independent of active transport mechanisms. These studies represent the first report of an anti-inflammatory marine natural product that selectively inhibits leukotriene biosynthesis.

  3. Cell Death Inducing Microbial Protein Phosphatase Inhibitors--Mechanisms of Action.

    PubMed

    Kleppe, Rune; Herfindal, Lars; Døskeland, Stein Ove

    2015-10-01

    Okadaic acid (OA) and microcystin (MC) as well as several other microbial toxins like nodularin and calyculinA are known as tumor promoters as well as inducers of apoptotic cell death. Their intracellular targets are the major serine/threonine protein phosphatases. This review summarizes mechanisms believed to be responsible for the death induction and tumor promotion with focus on the interdependent production of reactive oxygen species (ROS) and activation of Ca(2+)/calmodulin kinase II (CaM-KII). New data are presented using inhibitors of specific ROS producing enzymes to curb nodularin/MC-induced liver cell (hepatocyte) death. They indicate that enzymes of the arachidonic acid pathway, notably phospholipase A2, 5-lipoxygenase, and cyclooxygenases, may be required for nodularin/MC-induced (and presumably OA-induced) cell death, suggesting new ways to overcome at least some aspects of OA and MC toxicity. PMID:26506362

  4. Protein-water dynamics in antifreeze protein III activity

    NASA Astrophysics Data System (ADS)

    Xu, Yao; Bäumer, Alexander; Meister, Konrad; Bischak, Connor G.; DeVries, Arthur L.; Leitner, David M.; Havenith, Martina

    2016-03-01

    We combine Terahertz absorption spectroscopy (THz) and molecular dynamics (MD) simulations to investigate the underlying molecular mechanism for the antifreeze activity of one class of antifreeze protein, antifreeze protein type III (AFP-III) with a focus on the collective water hydrogen bond dynamics near the protein. After summarizing our previous work on AFPs, we present a new investigation of the effects of cosolutes on protein antifreeze activity by adding sodium citrate to the protein solution of AFP-III. Our results reveal that for AFP-III, unlike some other AFPs, the addition of the osmolyte sodium citrate does not affect the hydrogen bond dynamics at the protein surface significantly, as indicated by concentration dependent THz measurements. The present data, in combination with our previous THz measurements and molecular simulations, confirm that while long-range solvent perturbation is a necessary condition for the antifreeze activity of AFP-III, the local binding affinity determines the size of the hysteresis.

  5. Endogenous protein phosphorylation and protein kinase activity in winged bean.

    PubMed

    Mukhopadhyay, K; Singh, M

    1997-10-01

    In winged bean (Psophocarpus tetragonolobus) protein kinases (E.C. 2.7.1.37) were found in all tissues studied. There was a significant increase in kinase activity during seed development, with a concomitant enhancement in the phosphorylation of a number of polypeptides; this was reversed in germinating seed cotyledons. Protein phosphorylation was apparently correlated with the increase in the protein content of the developing seed and the growing axis. At least three distinct autophosphorylating proteins could be distinguished in the developing seeds after SDS-PAGE, indicating the presence of different types of protein kinases in winged bean.

  6. Identification of intracellular receptor proteins for activated protein kinase C.

    PubMed Central

    Mochly-Rosen, D; Khaner, H; Lopez, J

    1991-01-01

    Protein kinase C (PKC) translocates from the cytosol to the particulate fraction on activation. This activation-induced translocation of PKC is thought to reflect PKC binding to the membrane lipids. However, immunological and biochemical data suggest that PKC may bind to proteins in the cytoskeletal elements in the particulate fraction and in the nuclei. Here we describe evidence for the presence of intracellular receptor proteins that bind activated PKC. Several proteins from the detergent-insoluble material of the particulate fraction bound PKC in the presence of phosphatidylserine and calcium; binding was further increased with the addition of diacylglycerol. Binding of PKC to two of these proteins was concentration-dependent, saturable, and specific, suggesting that these binding proteins are receptors for activated C-kinase, termed here "RACKs." PKC binds to RACKs via a site on PKC distinct from the substrate binding site. We suggest that binding to RACKs may play a role in activation-induced translocation of PKC. Images PMID:1850844

  7. Activity-Based Protein Profiling of Microbes

    SciTech Connect

    Sadler, Natalie C.; Wright, Aaron T.

    2015-02-01

    Activity-Based Protein Profiling (ABPP) in conjunction with multimodal characterization techniques has yielded impactful findings in microbiology, particularly in pathogen, bioenergy, drug discovery, and environmental research. Using small molecule chemical probes that react irreversibly with specific proteins or protein families in complex systems has provided insights in enzyme functions in central metabolic pathways, drug-protein interactions, and regulatory protein redox, for systems ranging from photoautotrophic cyanobacteria to mycobacteria, and combining live cell or cell extract ABPP with proteomics, molecular biology, modeling, and other techniques has greatly expanded our understanding of these systems. New opportunities for application of ABPP to microbial systems include: enhancing protein annotation, characterizing protein activities in myriad environments, and reveal signal transduction and regulatory mechanisms in microbial systems.

  8. Hydrogen peroxide activates activator protein-1 and mitogen-activated protein kinases in pancreatic stellate cells.

    PubMed

    Kikuta, Kazuhiro; Masamune, Atsushi; Satoh, Masahiro; Suzuki, Noriaki; Satoh, Kennichi; Shimosegawa, Tooru

    2006-10-01

    Activated pancreatic stellate cells (PSCs) are implicated in the pathogenesis of pancreatic inflammation and fibrosis, where oxidative stress is thought to play a key role. Reactive oxygen species such as hydrogen peroxide (H(2)O(2)) may act as a second messenger to mediate the actions of growth factors and cytokines. But the role of reactive oxygen species in the activation and regulation of cell functions in PSCs remains largely unknown. We here examined the effects of H(2)O(2) on the activation of signal transduction pathways and cell functions in PSCs. PSCs were isolated from the pancreas of male Wistar rats, and used in their culture-activated, myofibroblast-like phenotype unless otherwise stated. Activation of transcription factors was examined by electrophoretic mobility shift assay and luciferase assay. Activation of mitogen-activated protein (MAP) kinases was assessed by Western blotting using anti-phosphospecific antibodies. The effects of H(2)O(2) on proliferation, alpha(1)(I)procollagen gene expression, and monocyte chemoattractant protein-1 production were evaluated. The effect of H(2)O(2) on the transformation of freshly isolated PSCs in culture was also assessed. H(2)O(2) at non-cytotoxic concentrations (up to 100 microM) induced oxidative stress in PSCs. H(2)O(2) activated activator protein-1, but not nuclear factor kappaB. In addition, H(2)O(2) activated three classes of MAP kinases: extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 MAP kinase. H(2)O(2) induced alpha(1)(I)procollagen gene expression but did not induce proliferation or monocyte chemoattractant protein-1 production. H(2)O(2) did not initiate the transformation of freshly isolated PSCs to myofibroblast-like phenotype. Specific activation of these signal transduction pathways and collagen gene expression by H(2)O(2) may play a role in the pathogenesis of pancreatic fibrosis.

  9. Computational Introduction of Catalytic Activity into Proteins.

    PubMed

    Bertolani, Steve J; Carlin, Dylan Alexander; Siegel, Justin B

    2016-01-01

    Recently, there have been several successful cases of introducing catalytic activity into proteins. One method that has been used successfully to achieve this is the theozyme placement and enzyme design algorithms implemented in Rosetta Molecular Modeling Suite. Here, we illustrate how to use this software to recapitulate the placement of catalytic residues and ligand into a protein using a theozyme, protein scaffold, and catalytic constraints as input. PMID:27094294

  10. DNA-based control of protein activity

    PubMed Central

    Engelen, W.; Janssen, B. M. G.

    2016-01-01

    DNA has emerged as a highly versatile construction material for nanometer-sized structures and sophisticated molecular machines and circuits. The successful application of nucleic acid based systems greatly relies on their ability to autonomously sense and act on their environment. In this feature article, the development of DNA-based strategies to dynamically control protein activity via oligonucleotide triggers is discussed. Depending on the desired application, protein activity can be controlled by directly conjugating them to an oligonucleotide handle, or expressing them as a fusion protein with DNA binding motifs. To control proteins without modifying them chemically or genetically, multivalent ligands and aptamers that reversibly inhibit their function provide valuable tools to regulate proteins in a noncovalent manner. The goal of this feature article is to give an overview of strategies developed to control protein activity via oligonucleotide-based triggers, as well as hurdles yet to be taken to obtain fully autonomous systems that interrogate, process and act on their environments by means of DNA-based protein control. PMID:26812623

  11. Increased flexibility decreases antifreeze protein activity

    PubMed Central

    Patel, Shruti N; Graether, Steffen P

    2010-01-01

    Antifreeze proteins protect several cold-blooded organisms from subzero environments by preventing death from freezing. The Type I antifreeze protein (AFP) isoform from Pseudopleuronectes americanus, named HPLC6, is a 37-residue protein that is a single α-helix. Mutational analysis of the protein showed that its alanine-rich face is important for binding to and inhibiting the growth of macromolecular ice. Almost all structural studies of HPLC6 involve the use of chemically synthesized protein as it requires a native N-terminal aspartate and an amidated C-terminus for full activity. Here, we examine the role of C-terminal amide and C-terminal arginine side chain in the activity, structure, and dynamics of nonamidated Arg37 HPLC6, nonamidated HPLC6 Ala37, amidated HPLC6 Ala37, and fully native HPLC6 using a recombinant bacterial system. The thermal hysteresis (TH) activities of the nonamidated mutants are 35% lower compared with amidated proteins, but analysis of the NMR data and circular dichroism spectra shows that they are all still α-helical. Relaxation data from the two nonamidated mutants indicate that the C-terminal residues are considerably more flexible than the rest of the protein because of the loss of the amide group, whereas the amidated Ala37 mutant has a C-terminus that is as rigid as the wild-type protein and has high TH activity. We propose that an increase in flexibility of the AFP causes it to lose activity because its dynamic nature prevents it from binding strongly to the ice surface. PMID:20936690

  12. Active Nuclear Import of Membrane Proteins Revisited.

    PubMed

    Laba, Justyna K; Steen, Anton; Popken, Petra; Chernova, Alina; Poolman, Bert; Veenhoff, Liesbeth M

    2015-01-01

    It is poorly understood how membrane proteins destined for the inner nuclear membrane pass the crowded environment of the Nuclear Pore Complex (NPC). For the Saccharomyces cerevisiae proteins Src1/Heh1 and Heh2, a transport mechanism was proposed where the transmembrane domains diffuse through the membrane while the extralumenal domains encoding a nuclear localization signal (NLS) and intrinsically disordered linker (L) are accompanied by transport factors and travel through the NPC. Here, we validate the proposed mechanism and explore and discuss alternative interpretations of the data. First, to disprove an interpretation where the membrane proteins become membrane embedded only after nuclear import, we present biochemical and localization data to support that the previously used, as well as newly designed reporter proteins are membrane-embedded irrespective of the presence of the sorting signals, the specific transmembrane domain (multipass or tail anchored), independent of GET, and also under conditions that the proteins are trapped in the NPC. Second, using the recently established size limit for passive diffusion of membrane proteins in yeast, and using an improved assay, we confirm active import of polytopic membrane protein with extralumenal soluble domains larger than those that can pass by diffusion on similar timescales. This reinforces that NLS-L dependent active transport is distinct from passive diffusion. Thirdly, we revisit the proposed route through the center of the NPC and conclude that the previously used trapping assay is, unfortunately, poorly suited to address the route through the NPC, and the route thus remains unresolved. Apart from the uncertainty about the route through the NPC, the data confirm active, transport factor dependent, nuclear transport of membrane-embedded mono- and polytopic membrane proteins in baker's yeast. PMID:26473931

  13. Active Nuclear Import of Membrane Proteins Revisited

    PubMed Central

    Laba, Justyna K.; Steen, Anton; Popken, Petra; Chernova, Alina; Poolman, Bert; Veenhoff, Liesbeth M.

    2015-01-01

    It is poorly understood how membrane proteins destined for the inner nuclear membrane pass the crowded environment of the Nuclear Pore Complex (NPC). For the Saccharomyces cerevisiae proteins Src1/Heh1 and Heh2, a transport mechanism was proposed where the transmembrane domains diffuse through the membrane while the extralumenal domains encoding a nuclear localization signal (NLS) and intrinsically disordered linker (L) are accompanied by transport factors and travel through the NPC. Here, we validate the proposed mechanism and explore and discuss alternative interpretations of the data. First, to disprove an interpretation where the membrane proteins become membrane embedded only after nuclear import, we present biochemical and localization data to support that the previously used, as well as newly designed reporter proteins are membrane-embedded irrespective of the presence of the sorting signals, the specific transmembrane domain (multipass or tail anchored), independent of GET, and also under conditions that the proteins are trapped in the NPC. Second, using the recently established size limit for passive diffusion of membrane proteins in yeast, and using an improved assay, we confirm active import of polytopic membrane protein with extralumenal soluble domains larger than those that can pass by diffusion on similar timescales. This reinforces that NLS-L dependent active transport is distinct from passive diffusion. Thirdly, we revisit the proposed route through the center of the NPC and conclude that the previously used trapping assay is, unfortunately, poorly suited to address the route through the NPC, and the route thus remains unresolved. Apart from the uncertainty about the route through the NPC, the data confirm active, transport factor dependent, nuclear transport of membrane-embedded mono- and polytopic membrane proteins in baker’s yeast. PMID:26473931

  14. Protein kinase activators alter glial cholesterol esterification

    SciTech Connect

    Jeng, I.; Dills, C.; Klemm, N.; Wu, C.

    1986-05-01

    Similar to nonneural tissues, the activity of glial acyl-CoA cholesterol acyltransferase is controlled by a phosphorylation and dephosphorylation mechanism. Manipulation of cyclic AMP content did not alter the cellular cholesterol esterification, suggesting that cyclic AMP is not a bioregulator in this case. Therefore, the authors tested the effect of phorbol-12-myristate 13-acetate (PMA) on cellular cholesterol esterification to determine the involvement of protein kinase C. PMA has a potent effect on cellular cholesterol esterification. PMA depresses cholesterol esterification initially, but cells recover from inhibition and the result was higher cholesterol esterification, suggesting dual effects of protein kinase C. Studies of other phorbol analogues and other protein kinase C activators such as merezein indicate the involvement of protein kinase C. Oleoyl-acetyl glycerol duplicates the effect of PMA. This observation is consistent with a diacyl-glycerol-protein kinase-dependent reaction. Calcium ionophore A23187 was ineffective in promoting the effect of PMA. They concluded that a calcium-independent and protein C-dependent pathway regulated glial cholesterol esterification.

  15. Active Wnt proteins are secreted on exosomes.

    PubMed

    Gross, Julia Christina; Chaudhary, Varun; Bartscherer, Kerstin; Boutros, Michael

    2012-10-01

    Wnt signalling has important roles during development and in many diseases. As morphogens, hydrophobic Wnt proteins exert their function over a distance to induce patterning and cell differentiation decisions. Recent studies have identified several factors that are required for the secretion of Wnt proteins; however, how Wnts travel in the extracellular space remains a largely unresolved question. Here we show that Wnts are secreted on exosomes both during Drosophila development and in human cells. We demonstrate that exosomes carry Wnts on their surface to induce Wnt signalling activity in target cells. Together with the cargo receptor Evi/WIs, Wnts are transported through endosomal compartments onto exosomes, a process that requires the R-SNARE Ykt6. Our study demonstrates an evolutionarily conserved functional role of extracellular vesicular transport of Wnt proteins.

  16. Total Cellular RNA Modulates Protein Activity.

    PubMed

    Majumder, Subhabrata; DeMott, Christopher M; Reverdatto, Sergey; Burz, David S; Shekhtman, Alexander

    2016-08-16

    RNA constitutes up to 20% of a cell's dry weight, corresponding to ∼20 mg/mL. This high concentration of RNA facilitates low-affinity protein-RNA quinary interactions, which may play an important role in facilitating and regulating biological processes. In the yeast Pichia pastoris, the level of ubiquitin-RNA colocalization increases when cells are grown in the presence of dextrose and methanol instead of methanol as the sole carbon source. Total RNA isolated from cells grown in methanol increases β-galactosidase activity relative to that seen with RNA isolated from cells grown in the presence of dextrose and methanol. Because the total cellular RNA content changes with growth medium, protein-RNA quinary interactions can alter in-cell protein biochemistry and may play an important role in cell adaptation, critical to many physiological and pathological states. PMID:27456029

  17. Electrochemical Activation of Engineered Protein Switches

    PubMed Central

    Choi, Jay H.; Zayats, Maya; Searson, Peter C.; Ostermeier, Marc

    2016-01-01

    Engineered protein switches have a large dynamic range, high specificity for the activating ligand, and a modular architecture, and have been explored for a wide range of applications including biosensors and therapeutics. The ability to externally control switch function is important in extending applications for protein switches. We recently demonstrated that the on/off state could be controlled by the redox state of disulfide bonds introduced into the switches at select locations. Here, we demonstrate that an electrochemical signal can be used as an exogenous input to control switch function via reduction of the engineered disulfide bonds. This study suggests that disulfide-containing protein switch is a potentially useful platform for bioelectronic sensors with remote control of the sensing ability. PMID:26241391

  18. Analysis of mitogen-activated protein kinase activity in yeast.

    PubMed

    Elion, Elaine A; Sahoo, Rupam

    2010-01-01

    Mitogen-activated protein (MAP) kinases play central roles in transmitting extracellular and intracellular information in a wide variety of situations in eukaryotic cells. Their activities are perturbed in a large number of diseases, and their activating kinases are currently therapeutic targets in cancer. MAPKs are highly conserved among all eukaryotes. MAPKs were first cloned from the yeast Saccharomyces cerevisiae. Yeast has five MAPKs and one MAPK-like kinase. The mating MAPK Fus3 is the best characterized yeast MAPK. Members of all subfamilies of human MAPKs can functionally substitute S. cerevisiae MAPKs, providing systems to use genetic approaches to study the functions of either yeast or human MAPKs and to identify functionally relevant amino acid residues that enhance or reduce the effects of therapeutically relevant inhibitors and regulatory proteins. Here, we describe an assay to measure Fus3 activity in immune complexes prepared from S. cerevisiae extracts. The assay conditions are applicable to other MAPKs, as well. PMID:20811996

  19. De Novo Construction of Redox Active Proteins.

    PubMed

    Moser, C C; Sheehan, M M; Ennist, N M; Kodali, G; Bialas, C; Englander, M T; Discher, B M; Dutton, P L

    2016-01-01

    Relatively simple principles can be used to plan and construct de novo proteins that bind redox cofactors and participate in a range of electron-transfer reactions analogous to those seen in natural oxidoreductase proteins. These designed redox proteins are called maquettes. Hydrophobic/hydrophilic binary patterning of heptad repeats of amino acids linked together in a single-chain self-assemble into 4-alpha-helix bundles. These bundles form a robust and adaptable frame for uncovering the default properties of protein embedded cofactors independent of the complexities introduced by generations of natural selection and allow us to better understand what factors can be exploited by man or nature to manipulate the physical chemical properties of these cofactors. Anchoring of redox cofactors such as hemes, light active tetrapyrroles, FeS clusters, and flavins by His and Cys residues allow cofactors to be placed at positions in which electron-tunneling rates between cofactors within or between proteins can be predicted in advance. The modularity of heptad repeat designs facilitates the construction of electron-transfer chains and novel combinations of redox cofactors and new redox cofactor assisted functions. Developing de novo designs that can support cofactor incorporation upon expression in a cell is needed to support a synthetic biology advance that integrates with natural bioenergetic pathways. PMID:27586341

  20. Synaptic Vesicle Proteins and Active Zone Plasticity.

    PubMed

    Kittel, Robert J; Heckmann, Manfred

    2016-01-01

    Neurotransmitter is released from synaptic vesicles at the highly specialized presynaptic active zone (AZ). The complex molecular architecture of AZs mediates the speed, precision and plasticity of synaptic transmission. Importantly, structural and functional properties of AZs vary significantly, even for a given connection. Thus, there appear to be distinct AZ states, which fundamentally influence neuronal communication by controlling the positioning and release of synaptic vesicles. Vice versa, recent evidence has revealed that synaptic vesicle components also modulate organizational states of the AZ. The protein-rich cytomatrix at the active zone (CAZ) provides a structural platform for molecular interactions guiding vesicle exocytosis. Studies in Drosophila have now demonstrated that the vesicle proteins Synaptotagmin-1 (Syt1) and Rab3 also regulate glutamate release by shaping differentiation of the CAZ ultrastructure. We review these unexpected findings and discuss mechanistic interpretations of the reciprocal relationship between synaptic vesicles and AZ states, which has heretofore received little attention.

  1. Synaptic Vesicle Proteins and Active Zone Plasticity

    PubMed Central

    Kittel, Robert J.; Heckmann, Manfred

    2016-01-01

    Neurotransmitter is released from synaptic vesicles at the highly specialized presynaptic active zone (AZ). The complex molecular architecture of AZs mediates the speed, precision and plasticity of synaptic transmission. Importantly, structural and functional properties of AZs vary significantly, even for a given connection. Thus, there appear to be distinct AZ states, which fundamentally influence neuronal communication by controlling the positioning and release of synaptic vesicles. Vice versa, recent evidence has revealed that synaptic vesicle components also modulate organizational states of the AZ. The protein-rich cytomatrix at the active zone (CAZ) provides a structural platform for molecular interactions guiding vesicle exocytosis. Studies in Drosophila have now demonstrated that the vesicle proteins Synaptotagmin-1 (Syt1) and Rab3 also regulate glutamate release by shaping differentiation of the CAZ ultrastructure. We review these unexpected findings and discuss mechanistic interpretations of the reciprocal relationship between synaptic vesicles and AZ states, which has heretofore received little attention. PMID:27148040

  2. Development of Novel Adenosine Monophosphate-Activated Protein Kinase Activators

    PubMed Central

    Guh, Jih-Hwa; Chang, Wei-Ling; Yang, Jian; Lee, Su-Lin; Wei, Shuo; Wang, Dasheng; Kulp, Samuel K.; Chen, Ching-Shih

    2010-01-01

    In light of the unique ability of thiazolidinediones to mediate peroxisome proliferator-activated receptor (PPAR)γ-independent activation of adenosine monophosphate-activated protein kinase (AMPK) and suppression of interleukin (IL)-6 production, we conducted a screening of an in-house, thiazolidinedione-based focused compound library to identify novel agents with these dual pharmacological activities. Cell-based assays pertinent to the activation status of AMPK and mammalian homolog of target of rapamycin (i.e., phosphorylation of AMPK and p70 ribosomal protein S6 kinase, respectively), and IL-6/IL-6 receptor signaling (i.e., IL-6 production and signal transducer and activator of transcription 3 phosphorylation, respectively) in lipopolysaccharide (LPS)-stimulated THP-1 human macrophages were used to screen this compound library, which led to the identification of compound 53 (N-{4-[3-(1-Methylcyclohexylmethyl)-2,4-dioxo-thiazolidin-5-ylidene-methyl]-phenyl}-4-nitro-3-trifluoromethyl-benzenesulfonamide) as the lead agent. Evidence indicates that this drug-induced suppression of LPS-stimulated IL-6 production was attributable to AMPK activation. Furthermore, compound 53-mediated AMPK activation was demonstrated in C-26 colon adenocarcinoma cells, indicating that it is not a cell line-specific event. PMID:20170185

  3. Comparison of Metalloproteinase Protein and Activity Profiling

    PubMed Central

    Giricz, Orsi; Lauer, Janelle L.; Fields, Gregg B.

    2010-01-01

    Proteolytic enzymes play fundamental roles in many biological processes. Members of the matrix metalloproteinase (MMP) family have been shown to take part in processes crucial in disease progression. The present study used the ExcelArray Human MMP/TIMP Array to quantify MMP and tissue inhibitor of metalloproteinase (TIMP) production in the lysates and media of 14 cancer and one normal cell line. The overall patterns were very similar in terms of which MMPs and TIMPs were secreted in the media versus associated with the cells in the individual samples. However, more MMP was found in the media, both in amount and in variety. TIMP-1 was produced in all cell lines. MMP activity assays with three different FRET substrates were then utilized to determine if protein production correlated with function for the WM-266-4 and BJ cell lines. Metalloproteinase activity was observed for both cell lines with a general MMP substrate (Knight SSP), consistent with protein production data. However, although both cell lines promoted the hydrolysis of a more selective MMP substrate (NFF-3), metalloproteinase activity was only confirmed in the BJ cell line. The use of inhibitors to confirm metalloproteinase activities pointed to the strengths and weaknesses of in situ FRET substrate assays. PMID:20920458

  4. Crowding Activates Heat Shock Protein 90.

    PubMed

    Halpin, Jackson C; Huang, Bin; Sun, Ming; Street, Timothy O

    2016-03-18

    Hsp90 is a dimeric ATP-dependent chaperone involved in the folding, maturation, and activation of diverse target proteins. Extensive in vitro structural analysis has led to a working model of Hsp90's ATP-driven conformational cycle. An implicit assumption is that dilute experimental conditions do not significantly perturb Hsp90 structure and function. However, Hsp90 undergoes a dramatic open/closed conformational change, which raises the possibility that this assumption may not be valid for this chaperone. Indeed, here we show that the ATPase activity of Hsp90 is highly sensitive to molecular crowding, whereas the ATPase activities of Hsp60 and Hsp70 chaperones are insensitive to crowding conditions. Polymer crowders activate Hsp90 in a non-saturable manner, with increasing efficacy at increasing concentration. Crowders exhibit a non-linear relationship between their radius of gyration and the extent to which they activate Hsp90. This experimental relationship can be qualitatively recapitulated with simple structure-based volume calculations comparing open/closed configurations of Hsp90. Thermodynamic analysis indicates that crowding activation of Hsp90 is entropically driven, which is consistent with a model in which excluded volume provides a driving force that favors the closed active state of Hsp90. Multiple Hsp90 homologs are activated by crowders, with the endoplasmic reticulum-specific Hsp90, Grp94, exhibiting the highest sensitivity. Finally, we find that crowding activation works by a different mechanism than co-chaperone activation and that these mechanisms are independent. We hypothesize that Hsp90 has a higher intrinsic activity in the cell than in vitro. PMID:26797120

  5. Synthesis and anti-inflammatory activity of chalcone derivatives.

    PubMed

    Herencia, F; Ferrándiz, M L; Ubeda, A; Domínguez, J N; Charris, J E; Lobo, G M; Alcaraz, M J

    1998-05-19

    Chalcones and their derivatives were synthesized and evaluated for their anti-inflammatory activity. In vitro, chalcones 2, 4, 8, 10 and 13 inhibited degranulation and 5-lipoxygenase in human neutrophils, whereas 11 behaved as scavenger of superoxide. Only four compounds (4-7) inhibited cyclo-oxygenase-2 activity. The majority of these samples showed anti-inflammatory effects in the mouse air pouch model.

  6. Polycarboxylates Enhance Beetle Antifreeze Protein Activity

    PubMed Central

    Amornwittawat, Natapol; Wang, Sen; Duman, John G.; Wen, Xin

    2008-01-01

    Summary Antifreeze proteins (AFPs) lower the noncolligative freezing point of water in the presence of ice below the ice melting point. The temperature difference between the melting point and the noncolligative freezing point is termed thermal hysteresis (TH). The magnitude of the TH depends on the specific activity and the concentration of AFP, and the concentration of enhancers in the solution. Known enhancers are certain low molecular mass molecules and proteins. Here, we investigated a series of polycarboxylates that enhance the TH activity of an AFP from the beetle Dendroides canadensis (DAFP) using differential scanning calorimetry (DSC). Triethylenetetramine-N,N,N′,N″,N‴,N‴-hexaacetate, the most efficient enhancer identified in this work, can increase the TH of DAFP by nearly 1.5 fold over than that of the published best enhancer, citrate. The Zn2+ coordinated carboxylate results in loss of the enhancement ability of the carboxylate on antifreeze activity. There is not an additional increase in TH when a weaker enhancer is added to a stronger enhancer solution. These observations suggest that the more carboxylate groups per enhancer molecule the better the efficiency of the enhancer and that the freedom of motion of these molecules is necessary for them to serve as enhancers for AFP. The hydroxyl groups in the enhancer molecules can also positively affect their TH enhancement efficiency, though not as strongly as carboxylate groups. Mechanisms are discussed. PMID:18620083

  7. [Protein kinase C activation induces platelet apoptosis].

    PubMed

    Zhao, Li-Li; Chen, Meng-Xing; Zhang, Ming-Yi; Dai, Ke-Sheng

    2013-10-01

    Platelet apoptosis elucidated by either physical or chemical compound or platelet storage occurs wildly, which might play important roles in controlling the numbers and functions of circulated platelets, or in the development of some platelet-related diseases. However, up to now, a little is known about the regulatory mechanisms of platelet apoptosis. Protein kinase C (PKC) is highly expressed in platelets and plays central roles in regulating platelet functions. Although there is evidence indicating that PKC is involved in the regulation of apoptosis of nucleated cells, it is still unclear whether PKC plays a role in platelet apoptosis. The aim of this study was to investigate the role of PKC in platelet apoptosis. The effects of PKC on mitochondrial membrane potential (ΔΨm), phosphatidylserine (PS) exposure, and caspase-3 activation of platelets were analyzed by flow cytometry and Western blot. The results showed that the ΔΨm depolarization in platelets was induced by PKC activator in time-dependent manner, and the caspase-3 activation in platelets was induced by PKC in concentration-dependent manner. However, the platelets incubated with PKC inhibitor did not results in ΔΨm depolarization and PS exposure. It is concluded that the PKC activation induces platelet apoptosis through influencing the mitochondrial functions and activating caspase 3. The finds suggest a novel mechanism for PKC in regulating platelet numbers and functions, which has important pathophysiological implications for thrombosis and hemostasis.

  8. Heat dissipation guides activation in signaling proteins

    PubMed Central

    Weber, Jeffrey K.; Shukla, Diwakar; Pande, Vijay S.

    2015-01-01

    Life is fundamentally a nonequilibrium phenomenon. At the expense of dissipated energy, living things perform irreversible processes that allow them to propagate and reproduce. Within cells, evolution has designed nanoscale machines to do meaningful work with energy harnessed from a continuous flux of heat and particles. As dictated by the Second Law of Thermodynamics and its fluctuation theorem corollaries, irreversibility in nonequilibrium processes can be quantified in terms of how much entropy such dynamics produce. In this work, we seek to address a fundamental question linking biology and nonequilibrium physics: can the evolved dissipative pathways that facilitate biomolecular function be identified by their extent of entropy production in general relaxation processes? We here synthesize massive molecular dynamics simulations, Markov state models (MSMs), and nonequilibrium statistical mechanical theory to probe dissipation in two key classes of signaling proteins: kinases and G-protein–coupled receptors (GPCRs). Applying machinery from large deviation theory, we use MSMs constructed from protein simulations to generate dynamics conforming to positive levels of entropy production. We note the emergence of an array of peaks in the dynamical response (transient analogs of phase transitions) that draw the proteins between distinct levels of dissipation, and we see that the binding of ATP and agonist molecules modifies the observed dissipative landscapes. Overall, we find that dissipation is tightly coupled to activation in these signaling systems: dominant entropy-producing trajectories become localized near important barriers along known biological activation pathways. We go on to classify an array of equilibrium and nonequilibrium molecular switches that harmonize to promote functional dynamics. PMID:26240354

  9. Phospholipases as GTPase activity accelerating proteins (GAPs) in plants.

    PubMed

    Pandey, Sona

    2016-05-01

    GTPase activity accelerating proteins (GAPs) are key regulators of the G-protein signaling cycle. By facilitating effective hydrolysis of the GTP bound on Gα proteins, GAPs control the timing and amplitude of the signaling cycle and ascertain the availability of the inactive heterotrimer for the next round of activation. Until very recently, the studies of GAPs in plants were focused exclusively on the regulator of G-protein signaling (RGS) protein. We now show that phospholipase Dα1 (PLDα1) is also a bona fide GAP in plants and together with the RGS protein controls the level of activeprotein. PMID:27124090

  10. Development of Potent Adenosine Monophosphate Activated Protein Kinase (AMPK) Activators.

    PubMed

    Dokla, Eman M E; Fang, Chun-Sheng; Lai, Po-Ting; Kulp, Samuel K; Serya, Rabah A T; Ismail, Nasser S M; Abouzid, Khaled A M; Chen, Ching-Shih

    2015-11-01

    Previously, we reported the identification of a thiazolidinedione-based adenosine monophosphate activated protein kinase (AMPK) activator, compound 1 (N-[4-({3-[(1-methylcyclohexyl)methyl]-2,4-dioxothiazolidin-5-ylidene}methyl)phenyl]-4-nitro-3-(trifluoromethyl)benzenesulfonamide), which provided a proof of concept to delineate the intricate role of AMPK in regulating oncogenic signaling pathways associated with cell proliferation and epithelial-mesenchymal transition (EMT) in cancer cells. In this study, we used 1 as a scaffold to conduct lead optimization, which generated a series of derivatives. Analysis of the antiproliferative and AMPK-activating activities of individual derivatives revealed a distinct structure-activity relationship and identified 59 (N-(3-nitrophenyl)-N'-{4-[(3-{[3,5-bis(trifluoromethyl)phenyl]methyl}-2,4-dioxothiazolidin-5-ylidene)methyl]phenyl}urea) as the optimal agent. Relative to 1, compound 59 exhibits multifold higher potency in upregulating AMPK phosphorylation in various cell lines irrespective of their liver kinase B1 (LKB1) functional status, accompanied by parallel changes in the phosphorylation/expression levels of p70S6K, Akt, Foxo3a, and EMT-associated markers. Consistent with its predicted activity against tumors with activated Akt status, orally administered 59 was efficacious in suppressing the growth of phosphatase and tensin homologue (PTEN)-null PC-3 xenograft tumors in nude mice. Together, these findings suggest that 59 has clinical value in therapeutic strategies for PTEN-negative cancer and warrants continued investigation in this regard.

  11. Receptor activity-modifying proteins; multifunctional G protein-coupled receptor accessory proteins.

    PubMed

    Hay, Debbie L; Walker, Christopher S; Gingell, Joseph J; Ladds, Graham; Reynolds, Christopher A; Poyner, David R

    2016-04-15

    Receptor activity-modifying proteins (RAMPs) are single pass membrane proteins initially identified by their ability to determine the pharmacology of the calcitonin receptor-like receptor (CLR), a family B G protein-coupled receptor (GPCR). It is now known that RAMPs can interact with a much wider range of GPCRs. This review considers recent developments on the structure of the complexes formed between the extracellular domains (ECDs) of CLR and RAMP1 or RAMP2 as these provide insights as to how the RAMPs direct ligand binding. The range of RAMP interactions is also considered; RAMPs can interact with numerous family B GPCRs as well as examples of family A and family C GPCRs. They influence receptor expression at the cell surface, trafficking, ligand binding and G protein coupling. The GPCR-RAMP interface offers opportunities for drug targeting, illustrated by examples of drugs developed for migraine. PMID:27068971

  12. Pyrrolopyridine inhibitors of mitogen-activated protein kinase-activated protein kinase 2 (MK-2).

    PubMed

    Anderson, David R; Meyers, Marvin J; Vernier, William F; Mahoney, Matthew W; Kurumbail, Ravi G; Caspers, Nicole; Poda, Gennadiy I; Schindler, John F; Reitz, David B; Mourey, Robert J

    2007-05-31

    A new class of potent kinase inhibitors selective for mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2 or MK-2) for the treatment of rheumatoid arthritis has been prepared and evaluated. These inhibitors have IC50 values as low as 10 nM against the target and have good selectivity profiles against a number of kinases including CDK2, ERK, JNK, and p38. These MK-2 inhibitors have been shown to suppress TNFalpha production in U397 cells and to be efficacious in an acute inflammation model. The structure-activity relationships of this series, the selectivity for MK-2 and their activity in both in vitro and in vivo models are discussed. The observed selectivity is discussed with the aid of an MK-2/inhibitor crystal structure.

  13. Arabinogalactan proteins: focus on carbohydrate active enzymes

    PubMed Central

    Knoch, Eva; Dilokpimol, Adiphol; Geshi, Naomi

    2014-01-01

    Arabinogalactan proteins (AGPs) are a highly diverse class of cell surface proteoglycans that are commonly found in most plant species. AGPs play important roles in many cellular processes during plant development, such as reproduction, cell proliferation, pattern formation and growth, and in plant-microbe interaction. However, little is known about the molecular mechanisms of their function. Numerous studies using monoclonal antibodies that recognize different AGP glycan epitopes have shown the appearance of a slightly altered AGP glycan in a specific stage of development in plant cells. Therefore, it is anticipated that the biosynthesis and degradation of AGP glycan is tightly regulated during development. Until recently, however, little was known about the enzymes involved in the metabolism of AGP glycans. In this review, we summarize recent discoveries of carbohydrate active enzymes (CAZy; http://www.cazy.org/) involved in the biosynthesis and degradation of AGP glycans, and we discuss the biological role of these enzymes in plant development. PMID:24966860

  14. Observation of microtubule-based motor protein activity.

    PubMed

    Sloboda, Roger D

    2015-02-01

    It is possible to detect the presence of motor proteins that have the ability to translocate particles along microtubules. The two procedures described here were developed to detect microtubule-dependent motor protein activity in cell lysates or of purified proteins. In the first procedure, latex beads bound to the putative motor protein are assayed for their ability to translocate along microtubules in an ATP-dependent fashion. If motor protein activity is present, it will bind to the beads and translocate them unidirectionally along the microtubules. In the second procedure, motor proteins induce microtubule gliding over a glass coverslip surface that is coated with active motor protein. Because the mass of a microtubule is negligible compared to that of a coverslip or slide, the microtubule glides over the glass surface when the surface is coated with active motor protein. Also included here are descriptions of assays designed to determine the directionality of movement of microtubule-based motor proteins. PMID:25646501

  15. Activating AMP-activated protein kinase (AMPK) slows renal cystogenesis.

    PubMed

    Takiar, Vinita; Nishio, Saori; Seo-Mayer, Patricia; King, J Darwin; Li, Hui; Zhang, Li; Karihaloo, Anil; Hallows, Kenneth R; Somlo, Stefan; Caplan, Michael J

    2011-02-01

    Renal cyst development and expansion in autosomal dominant polycystic kidney disease (ADPKD) involves both fluid secretion and abnormal proliferation of cyst-lining epithelial cells. The chloride channel of the cystic fibrosis transmembrane conductance regulator (CFTR) participates in secretion of cyst fluid, and the mammalian target of rapamycin (mTOR) pathway may drive proliferation of cyst epithelial cells. CFTR and mTOR are both negatively regulated by AMP-activated protein kinase (AMPK). Metformin, a drug in wide clinical use, is a pharmacological activator of AMPK. We find that metformin stimulates AMPK, resulting in inhibition of both CFTR and the mTOR pathways. Metformin induces significant arrest of cystic growth in both in vitro and ex vivo models of renal cystogenesis. In addition, metformin administration produces a significant decrease in the cystic index in two mouse models of ADPKD. Our results suggest a possible role for AMPK activation in slowing renal cystogenesis as well as the potential for therapeutic application of metformin in the context of ADPKD. PMID:21262823

  16. Biologically active LIL proteins built with minimal chemical diversity

    PubMed Central

    Heim, Erin N.; Marston, Jez L.; Federman, Ross S.; Edwards, Anne P. B.; Karabadzhak, Alexander G.; Petti, Lisa M.; Engelman, Donald M.; DiMaio, Daniel

    2015-01-01

    We have constructed 26-amino acid transmembrane proteins that specifically transform cells but consist of only two different amino acids. Most proteins are long polymers of amino acids with 20 or more chemically distinct side-chains. The artificial transmembrane proteins reported here are the simplest known proteins with specific biological activity, consisting solely of an initiating methionine followed by specific sequences of leucines and isoleucines, two hydrophobic amino acids that differ only by the position of a methyl group. We designate these proteins containing leucine (L) and isoleucine (I) as LIL proteins. These proteins functionally interact with the transmembrane domain of the platelet-derived growth factor β-receptor and specifically activate the receptor to transform cells. Complete mutagenesis of these proteins identified individual amino acids required for activity, and a protein consisting solely of leucines, except for a single isoleucine at a particular position, transformed cells. These surprisingly simple proteins define the minimal chemical diversity sufficient to construct proteins with specific biological activity and change our view of what can constitute an active protein in a cellular context. PMID:26261320

  17. G protein activation by G protein coupled receptors: ternary complex formation or catalyzed reaction?

    PubMed

    Roberts, David J; Waelbroeck, Magali

    2004-09-01

    G protein coupled receptors catalyze the GDP/GTP exchange on G proteins, thereby activating them. The ternary complex model, designed to describe agonist binding in the absence of GTP, is often extended to G protein activation. This is logically unsatisfactory as the ternary complex does not accumulate when G proteins are activated by GTP. Extended models taking into account nucleotide binding exist, but fail to explain catalytic G protein activation. This review puts forward an enzymatic model of G protein activation and compares its predictions with the ternary complex model and with observed receptor phenomenon. This alternative model does not merely provide a new set of formulae but leads to a new philosophical outlook and more readily accommodates experimental observations. The ternary complex model implies that, HRG being responsible for efficient G protein activation, it should be as stable as possible. In contrast, the enzyme model suggests that although a limited stabilization of HRG facilitates GDP release, HRG should not be "too stable" as this might trap the G protein in an inactive state and actually hinder G protein activation. The two models also differ completely in the definition of the receptor "active state": the ternary complex model implies that the active state corresponds to a single active receptor conformation (HRG); in contrast, the catalytic model predicts that the active receptor state is mobile, switching smoothly through various conformations with high and low affinities for agonists (HR, HRG, HRGGDP, HRGGTP, etc.).

  18. Receptor activity modifying protein-3 mediates the protumorigenic activity of lysyl oxidase-like protein-2.

    PubMed

    Brekhman, Vera; Lugassie, Jennie; Zaffryar-Eilot, Shelly; Sabo, Edmond; Kessler, Ofra; Smith, Victoria; Golding, Hana; Neufeld, Gera

    2011-01-01

    Lysyl oxidase-like protein-2 (LOXL2) induces epithelial to mesenchymal transition and promotes invasiveness. To understand the mechanisms involved, we examined the effect of LOXL2 overexpression in MCF-7 cells on gene expression. We found that LOXL2 up-regulated the expression of receptor activity modifying protein-3 (RAMP3). Expression of RAMP3 in MDA-MB-231 cells in which LOXL2 expression was inhibited restored vimentin expression, invasiveness, and tumor development. Inhibition of RAMP3 expression in MDA-MB-231 cells mimicked the effects produced by inhibition of LOXL2 expression and was accompanied by inhibition of p38 phosphorylation. LOXL2 overexpression in these cells did not restore invasiveness, suggesting that RAMP3 functions downstream to LOXL2. LOXL2 and RAMP3 are strongly coexpressed in human colon, breast, and gastric carcinomas but not in normal colon or gastric epithelial cells. RAMP3 associates with several G-protein-coupled receptors forming receptors for peptides, such as adrenomedullin and amylin. We hypothesized that RAMP3 could function as a transducer of autocrine signals induced by such peptides. However, the proinvasive effects of RAMP3 could not be abrogated following inhibition of the expression or activity of these peptides. Our experiments suggest that the protumorigenic effects of LOXL2 are partially mediated by RAMP3 and that RAMP3 inhibitors may function as antitumorigenic agents. -

  19. Modeling Protein Folding and Applying It to a Relevant Activity

    ERIC Educational Resources Information Center

    Nelson, Allan; Goetze, Jim

    2004-01-01

    The different levels of protein structure that can be easily understood by creating a model that simulates protein folding, which can then be evaluated by applying it to a relevant activity, is presented. The materials required and the procedure for constructing a protein folding model are mentioned.

  20. Dissecting the active site of a photoreceptor protein

    NASA Astrophysics Data System (ADS)

    Hoff, Wouter; Hara, Miwa; Ren, Jie; Moghadam, Farzaneh; Xie, Aihua; Kumauchi, Masato

    While enzymes are quite large molecules, functionally important chemical events are often limited to a small region of the protein: the active site. The physical and chemical properties of residues at such active sites are often strongly altered compared to the same groups dissolved in water. Understanding such effects is important for unraveling the mechanisms underlying protein function and for protein engineering, but has proven challenging. Here we report on our ongoing efforts on using photoactive yellow protein (PYP), a bacterial photoreceptor, as a model system for such effects. We will report on the following questions: How many residues affect active site properties? Are these residues in direct physical contact with the active site? Can functionally important residues be recognized in the crystal structure of a protein? What structural resolution is needed to understand active sites? What spectroscopic techniques are most informative? Which weak interactions dominate active site properties?

  1. Determination of Protein Carbonylation and Proteasome Activity in Seeds.

    PubMed

    Xia, Qiong; El-Maarouf-Bouteau, Hayat; Bailly, Christophe; Meimoun, Patrice

    2016-01-01

    Reactive oxygen species (ROS) have been shown to be toxic but also function as signaling molecules in a process called redox signaling. In seeds, ROS are produced at different developmental stages including dormancy release and germination. Main targets of oxidation events by ROS in cell are lipids, nucleic acids, and proteins. Protein oxidation has various effects on their function, stability, location, and degradation. Carbonylation represents an irreversible and unrepairable modification that can lead to protein degradation through the action of the 20S proteasome. Here, we present techniques which allow the quantification of protein carbonyls in complex protein samples after derivatization by 2,4-dinitrophenylhydrazine (DNPH) and the determination proteasome activity by an activity-based protein profiling (ABPP) using the probe MV151. These techniques, routinely easy to handle, allow the rapid assessment of protein carbonyls and proteasome activity in seeds in various physiological conditions where ROS may act as signaling or toxic elements. PMID:27424756

  2. Activated protein C anticoagulant system dysfunction and thrombophilia in Asia.

    PubMed

    Hamasaki, Naotaka; Kuma, Hiroyuki; Tsuda, Hiroko

    2013-01-01

    Thrombophilia that is common among Caucasians is caused by genetic polymorphisms of coagulation factor V Leiden (R506Q) and prothrombin G20210A. Unlike that in Caucasians, thrombophilia that is common in the Japanese and Chinese involve dysfunction of the activated protein C (APC) anticoagulant system caused by abnormal protein S and protein C molecules. Approximately 50% of Japanese and Chinese individuals who develop venous thrombosis have reduced activities of protein S. The abnormal sites causing the protein S molecule abnormalities are distributed throughout the protein S gene, PROS1. One of the most common abnormalities is protein S Tokushima (K155E), which accounts for about 30% of the protein S molecule abnormalities in the Japanese. Whether APC dysfunction occurs in other Asian countries is an important aspect of mapping thrombophilia among Asians. International surveys using an accurate assay system are needed to determine this.

  3. Global Analysis of Protein Activities Using Proteome Chips

    NASA Astrophysics Data System (ADS)

    Zhu, Heng; Bilgin, Metin; Bangham, Rhonda; Hall, David; Casamayor, Antonio; Bertone, Paul; Lan, Ning; Jansen, Ronald; Bidlingmaier, Scott; Houfek, Thomas; Mitchell, Tom; Miller, Perry; Dean, Ralph A.; Gerstein, Mark; Snyder, Michael

    2001-09-01

    To facilitate studies of the yeast proteome, we cloned 5800 open reading frames and overexpressed and purified their corresponding proteins. The proteins were printed onto slides at high spatial density to form a yeast proteome microarray and screened for their ability to interact with proteins and phospholipids. We identified many new calmodulin- and phospholipid-interacting proteins; a common potential binding motif was identified for many of the calmodulin-binding proteins. Thus, microarrays of an entire eukaryotic proteome can be prepared and screened for diverse biochemical activities. The microarrays can also be used to screen protein-drug interactions and to detect posttranslational modifications.

  4. The expression and activity of 5-LOX in the large intestine of horses harbouring encysted cyathostomin larvae.

    PubMed

    Giacominelli-Stuffler, Roberto; Frangipane di Regalbono, Antonio; Traversa, Donato; Geurden, Thomas; Marcer, Federica; Di Francesco, Andrea; Angelini, Chiara; di Cesare, Angela; Storelli, Maria Maddalena; Maccarrone, Mauro

    2014-06-16

    Leukotrienes are products of the arachidonic acid metabolism and act as potent inflammatory mediators modulating the immune response and various physiological processes. This study evaluated the expression and activity of 5-lipoxygenase (5-LOX), the enzyme that catalyzes the first two steps in the biosynthesis of leukotrienes, in horses infected by larval cyathostomins. Tissue samples from dorsal and ventral colon, and from the cecum were collected from 16 horses slaughtered for human consumption. Samples were analyzed to estimate the burdens of encysted cyathostomin larvae and adult luminal stages, and then processed for the evaluation of biochemical parameters. No significant differences were found in the protein expression and enzymatic activity of 5-LOX between animals harbouring only adult parasites and negative horses. The protein expression and enzyme activity of 5-LOX were significantly higher in horses harbouring encysted larvae in comparison with horses free of encysted larvae. Although preliminary, these results indicate that 5-LOX is an important mediator in the course of horse cyathostominosis and further studies are warranted to unveil the possible role this enzyme plays in the pathogenesis of horse cyathostominosis, and its potential as a diagnostic marker.

  5. The antioxidant effect of β-caryophyllene protects rat liver from carbon tetrachloride-induced fibrosis by inhibiting hepatic stellate cell activation.

    PubMed

    Calleja, Miguel Angel; Vieites, Jose María; Montero-Meléndez, Trinidad; Montero-Meterdez, Trinidad; Torres, María Isabel; Faus, María José; Gil, Angel; Suárez, Antonio

    2013-02-14

    Plant-based whole foods provide thousands of bioactive metabolites to the human diet that reduce the risk of developing chronic diseases. β-Caryophyllene (CAR) is a common constituent of the essential oil of numerous plants, vegetables, fruits and medicinal herbs, and has been used as a flavouring agent since the 1930 s. Here, we report the antioxidant activity of CAR, its protective effect on liver fibrosis and its inhibitory capacity on hepatic stellate cell (HSC) activation. CAR was tested for the inhibition of lipid peroxidation and as a free radical scavenger. CAR had higher inhibitory capacity on lipid peroxidation than probucol, α-humulene and α-tocopherol. Also, CAR showed high scavenging activities against hydroxyl radical and superoxide anion. The activity of 5-lipoxygenase, an enzyme that actively participates in fibrogenesis, was significantly inhibited by CAR. Carbon tetrachloride-treated rats received CAR at 2, 20 and 200 mg/kg. CAR significantly improved liver structure, and reduced fibrosis and the expression of Col1a1, Tgfb1 and Timp1 genes. Oxidative stress was used to establish a model of HSC activation with overproduction of extracellular matrix proteins. CAR (1 and 10 μm) increased cell viability and significantly reduced the expression of fibrotic marker genes. CAR, a sesquiterpene present in numerous plants and foods, is as a natural antioxidant that reduces carbon tetrachloride-mediated liver fibrosis and inhibits hepatic cell activation.

  6. Protein C activity in dogs envenomed by Vipera palaestinae.

    PubMed

    Hadar, Gil; Kelmer, Efrat; Segev, Gilad; Bruchim, Yaron; Aroch, Itamar

    2014-09-01

    Vipera palaestinae is responsible for most envenomations in humans and domestic animal in Israel. Its venom has pro- and anticoagulant properties. Protein C is a major natural anticoagulant, preventing excess clotting and thrombosis. This study investigated protein C activity and its prognostic value, as well as several other hemostatic analytes in dogs (Canis familiaris) accidently envenomed by V. palaestinae. Protein C activity was compared between envenomed dogs and 33 healthy control dogs. Mean protein C was lower in dogs envenomed by V. palaestinae compared to controls (12.9% vs. 22.9%, respectively; P < 0.01). It was positively correlated with antithrombin activity (r = 0.3, P = 0.04), but not with other hemostatic analytes. The overall mortality rate was 13%, and at presentation no significant protein C activity difference was noted between survivors and non-survivors. A receiver operator characteristics analysis of protein C activity as a predictor of mortality had an area under the curve of 0.7 (95% confidence interval 0.52-0.87). A protein C cutoff point of 8% corresponded to sensitivity and specificity of 70% and 57%, respectively. Dogs diagnosed with consumptive coagulopathy (14%) tended to have lower protein C activity compared to others; however, their mortality did differ from that of other dogs. This is the first study assessing protein C activity in V. palaestinae victims. Decreased protein C activity in such dogs may play a role in formation of thrombosis and hemostatic derangement as well as inflammation in V. palaestinae envenomations.

  7. Anthocyanidins inhibit activator protein 1 activity and cell transformation: structure-activity relationship and molecular mechanisms.

    PubMed

    Hou, De-Xing; Kai, Keiko; Li, Jian-Jian; Lin, Shigang; Terahara, Norihiko; Wakamatsu, Mika; Fujii, Makoto; Young, Mattew R; Colburn, Nancy

    2004-01-01

    Anthocyanins are the chemical components that give the intense color to many fruits and vegetables, such as blueberries, red cabbages and purple sweet potatoes. Extensive studies have indicated that anthocyanins have strong antioxidant activities. To investigate the mechanism of anthocyanidins as an anticancer food source, six kinds of anthocyanidins representing the aglycons of most anthocyanins, were used to examine their effects on tumor promotion in mouse JB6 cells, a validated model for screening cancer chemopreventive agents and elucidating the molecular mechanisms. Of the six anthocyanins tested, only those with an ortho-dihydroxyphenyl structure on the B-ring suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell transformation and activator protein-1 transactivation, suggesting that the ortho-dihydroxyphenyl may contribute to the inhibitory action. Delphinidin, but not peonidin, blocked the phosphorylation of protein kinases in the extracellular signal-regulated protein kinase (ERK) pathway at early times and the c-Jun N-terminal kinase (JNK) signaling pathway at later times. p38 kinase was not inhibited by delphinidin. Furthermore, two mitogen-activated protein kinase (MAPK) specific inhibitors (SP600125 for JNK and UO126 for ERK) could specifically block the activation of JNK and ERK and cell transformation. Those results demonstrate that anthocyanidins contribute to the inhibition of tumorigenesis by blocking activation of the MAPK pathway. These findings provide the first molecular basis for the anticarcinogenic action of anthocyanidins. PMID:14514663

  8. Anthocyanidins inhibit activator protein 1 activity and cell transformation: structure-activity relationship and molecular mechanisms.

    PubMed

    Hou, De-Xing; Kai, Keiko; Li, Jian-Jian; Lin, Shigang; Terahara, Norihiko; Wakamatsu, Mika; Fujii, Makoto; Young, Mattew R; Colburn, Nancy

    2004-01-01

    Anthocyanins are the chemical components that give the intense color to many fruits and vegetables, such as blueberries, red cabbages and purple sweet potatoes. Extensive studies have indicated that anthocyanins have strong antioxidant activities. To investigate the mechanism of anthocyanidins as an anticancer food source, six kinds of anthocyanidins representing the aglycons of most anthocyanins, were used to examine their effects on tumor promotion in mouse JB6 cells, a validated model for screening cancer chemopreventive agents and elucidating the molecular mechanisms. Of the six anthocyanins tested, only those with an ortho-dihydroxyphenyl structure on the B-ring suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell transformation and activator protein-1 transactivation, suggesting that the ortho-dihydroxyphenyl may contribute to the inhibitory action. Delphinidin, but not peonidin, blocked the phosphorylation of protein kinases in the extracellular signal-regulated protein kinase (ERK) pathway at early times and the c-Jun N-terminal kinase (JNK) signaling pathway at later times. p38 kinase was not inhibited by delphinidin. Furthermore, two mitogen-activated protein kinase (MAPK) specific inhibitors (SP600125 for JNK and UO126 for ERK) could specifically block the activation of JNK and ERK and cell transformation. Those results demonstrate that anthocyanidins contribute to the inhibition of tumorigenesis by blocking activation of the MAPK pathway. These findings provide the first molecular basis for the anticarcinogenic action of anthocyanidins.

  9. Breadboard activities for advanced protein crystal growth

    NASA Technical Reports Server (NTRS)

    Rosenberger, Franz; Banish, Michael

    1993-01-01

    The proposed work entails the design, assembly, testing, and delivery of a turn-key system for the semi-automated determination of protein solubilities as a function of temperature. The system will utilize optical scintillation as a means of detecting and monitoring nucleation and crystallite growth during temperature lowering (or raising, with retrograde solubility systems). The deliverables of this contract are: (1) turn-key scintillation system for the semi-automatic determination of protein solubilities as a function of temperature, (2) instructions and software package for the operation of the scintillation system, and (3) one semi-annual and one final report including the test results obtained for ovostatin with the above scintillation system.

  10. Visualizing active membrane protein complexes by electron cryotomography

    PubMed Central

    Gold, Vicki A.M.; Ieva, Raffaele; Walter, Andreas; Pfanner, Nikolaus; van der Laan, Martin; Kühlbrandt, Werner

    2014-01-01

    Unravelling the structural organization of membrane protein machines in their active state and native lipid environment is a major challenge in modern cell biology research. Here we develop the STAMP (Specifically TArgeted Membrane nanoParticle) technique as a strategy to localize protein complexes in situ by electron cryotomography (cryo-ET). STAMP selects active membrane protein complexes and marks them with quantum dots. Taking advantage of new electron detector technology that is currently revolutionizing cryotomography in terms of achievable resolution, this approach enables us to visualize the three-dimensional distribution and organization of protein import sites in mitochondria. We show that import sites cluster together in the vicinity of crista membranes, and we reveal unique details of the mitochondrial protein import machinery in action. STAMP can be used as a tool for site-specific labelling of a multitude of membrane proteins by cryo-ET in the future. PMID:24942077

  11. Antioxidant activities of protein hydrolysates obtained from the housefly larvae.

    PubMed

    Zhang, Huan; Wang, Pan; Zhang, Ai-Jun; Li, Xuan; Zhang, Ji-Hong; Qin, Qi-Lian; Wu, Yi-Jun

    2016-09-01

    The housefly is an important resource insect and the housefly larvae are ideal source of food additives. The housefly larvae protein hydrolysates were obtained by enzymatic hydrolysis by alcalase and neutral proteinase. Their antioxidant activities were investigated, including the superoxide and hydroxyl radicalscavenging activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, reducing power and metal chelating activity. The antioxidant activities of both hydrolysates increased with their increasing concentrations. The alcalase hydrolysate (AH) showed higher scavenging activities against hydroxyl radical and superoxide anion radical at low concentrations and higher metal-chelating activity than the neutral proteinase hydrolysate (NPH). The NPH exhibited higher scavenging activity against DPPH free radical and higher reducing power than the AH. Both hydrolysates showed more than 50% superoxide anion radical-scavenging activity at 10 μg/mL. These results indicate that both housefly larvae protein hydrolysates display high antioxidant activities and they could serve as potential natural antioxidant food additives. PMID:27630047

  12. Controlled Activation of Protein Rotational Dynamics Using Smart Hydrogel Tethering

    SciTech Connect

    Beech, Brenda M.; Xiong, Yijia; Boschek, Curt B.; Baird, Cheryl L.; Bigelow, Diana J.; Mcateer, Kathleen; Squier, Thomas C.

    2014-09-05

    Stimulus-responsive hydrogel materials that stabilize and control protein dynamics have the potential to enable a range of applications to take advantage of the inherent specificity and catalytic efficiencies of proteins. Here we describe the modular construction of a hydrogel using an engineered calmodulin (CaM) within a polyethylene glycol (PEG) matrix that involves the reversible tethering of proteins through an engineered CaM-binding sequence. For these measurements, maltose binding protein (MBP) was isotopically labeled with [13C] and [15N], permitting dynamic structural measurements using TROSY-HSQC NMR spectroscopy. Upon initial formation of hydrogels protein dynamics are suppressed, with concomitant increases in protein stability. Relaxation of the hydrogel matrix following transient heating results in the activation of protein dynamics and restoration of substrate-induced large-amplitude domain motions necessary for substrate binding.

  13. Hox proteins: sculpting body parts by activating localized cell death.

    PubMed

    Alonso, Claudio R

    2002-11-19

    Hox proteins shape animal structures by eliciting different developmental programs along the anteroposterior body axis. A recent study reveals that the Drosophila Hox protein Deformed directly activates the cell-death-promoting gene reaper to maintain the boundaries between distinct head segments.

  14. Modeling the SHG activities of diverse protein crystals

    SciTech Connect

    Haupert, Levi M.; DeWalt, Emma L.; Simpson, Garth J.

    2012-11-01

    The origins of the diversity in the SHG signal from protein crystals are investigated and potential protein-crystal coverage by SHG microscopy is assessed. A symmetry-additive ab initio model for second-harmonic generation (SHG) activity of protein crystals was applied to assess the likely protein-crystal coverage of SHG microscopy. Calculations were performed for 250 proteins in nine point-group symmetries: a total of 2250 crystals. The model suggests that the crystal symmetry and the limit of detection of the instrument are expected to be the strongest predictors of coverage of the factors considered, which also included secondary-structural content and protein size. Much of the diversity in SHG activity is expected to arise primarily from the variability in the intrinsic protein response as well as the orientation within the crystal lattice. Two or more orders-of-magnitude variation in intensity are expected even within protein crystals of the same symmetry. SHG measurements of tetragonal lysozyme crystals confirmed detection, from which a protein coverage of ∼84% was estimated based on the proportion of proteins calculated to produce SHG responses greater than that of tetragonal lysozyme. Good agreement was observed between the measured and calculated ratios of the SHG intensity from lysozyme in tetragonal and monoclinic lattices.

  15. Hemagglutinating activity of proteins from Parkia speciosa seeds.

    PubMed

    Chankhamjon, Kanokwan; Petsom, Amorn; Sawasdipuksa, Narumon; Sangvanich, Polkit

    2010-01-01

    Proteins from Parkia speciosa Hassk. (Fabaceae) seeds were extracted and stepwise precipitated using ammonium sulfate. Proteins precipitated with 25% ammonium sulfate were separated by affinity chromatography on Affi-Gel Blue gel followed by protein liquid chromatography on Superdex 200. The protein Gj, which was identified as a protein similar to putative aristolochene synthase, 3'-partial from Oryza sativa L. (Poaceae), had hemagglutinating activity of 0.39 mug/muL. Moreover, fraction C2 from the proteins precipitated with 60% ammonium sulfate, separated by lectin-specific adsorption chromatography using Con A Sepharose, had hemagglutinating activity of 1.17 mug/muL. Using gel electrophoresis, two proteins C2a and C2b were separated, having molecular weights of 45 kDa and 23 kDa, respectively. From protein identification, C2a was found to be similar to the hypothetical protein B1342F01.11 from Oryza sativa, and C2b was similar to the hypothetical protein At1g51560 from Arabidopsis thaliana (L.) Heynh. (Brassicaceae). PMID:20645760

  16. Differential regulation of protein subdomain activity with caged bivalent ligands.

    PubMed

    Mayer, Günter; Müller, Jens; Mack, Timo; Freitag, Daniel F; Höver, Thomas; Pötzsch, Bernd; Heckel, Alexander

    2009-03-01

    Subtle change: Spatiotemporal modulation of individual protein subdomains with light as the trigger signal becomes possible by using bivalent aptamers and introducing photolabile "caging groups" to switch individual aptamer modules ON or OFF differentially. To the best of our knowledge, this is the first study to show that it is possible to modulate individual domain activity in aptamers, and thus also domain activity in proteins, with light.

  17. Cloning of three novel neuronal Cdk5 activator binding proteins.

    PubMed

    Ching, Y P; Qi, Z; Wang, J H

    2000-01-25

    Neuronal Cdc2-like kinase (Nclk) is involved in the regulation of neuronal differentiation and neuro-cytoskeleton dynamics. The active kinase consists of a catalytic subunit, Cdk5, and a 25 kDa activator protein (p25nck5a) derived from a 35 kDa neuronal-specific protein (p35nck5a). As an extension of our previous study (Qi, Z., Tang, D., Zhu, X., Fujita, D.J., Wang, J.H., 1998. Association of neurofilament proteins with neuronal Cdk5 activator. J. Biol. Chem. 270, 2329-2335), which showed that neurofilament is one of the p35nck5a-associated proteins, we now report the isolation of three other novel p35nck5a-associated proteins using the yeast two-hybrid screen. The full-length forms of these three novel proteins, designated C42, C48 and C53, have a molecular mass of 66, 24, and 57 kDa, respectively. Northern analysis indicates that these novel proteins are widely expressed in human tissues, including the heart, brain, skeletal muscle, placenta, lung, liver, kidney and pancreas. The bacterially expressed glutathione S-transferase (GST)-fusion forms of these three proteins were able to co-precipitate p35nck5a complexed with Cdk5 from insect cell lysate. Among these three proteins, only C48 and C53 can be phosphorylated by Nclk, suggesting that they may be the substrates of Nclk. Sequence homology searches have suggested that the C48 protein is marginally related to restin protein, whereas the C42 protein has homologues of unknown function in Caenorhabditis elegans and Arabidopsis thaliana. PMID:10721722

  18. Activation of an Endoribonuclease by Non-intein Protein Splicing.

    PubMed

    Campbell, Stephen J; Stern, David B

    2016-07-29

    The Chlamydomonas reinhardtii chloroplast-localized poly(A)-binding protein RB47 is predicted to contain a non-conserved linker (NCL) sequence flanked by highly conserved N- and C-terminal sequences, based on the corresponding cDNA. RB47 was purified from chloroplasts in association with an endoribonuclease activity; however, protein sequencing failed to detect the NCL. Furthermore, while recombinant RB47 including the NCL did not display endoribonuclease activity in vitro, versions lacking the NCL displayed strong activity. Both full-length and shorter forms of RB47 could be detected in chloroplasts, with conversion to the shorter form occurring in chloroplasts isolated from cells grown in the light. This conversion could be replicated in vitro in chloroplast extracts in a light-dependent manner, where epitope tags and protein sequencing showed that the NCL was excised from a full-length recombinant substrate, together with splicing of the flanking sequences. The requirement for endogenous factors and light differentiates this protein splicing from autocatalytic inteins, and may allow the chloroplast to regulate the activation of RB47 endoribonuclease activity. We speculate that this protein splicing activity arose to post-translationally repair proteins that had been inactivated by deleterious insertions or extensions. PMID:27311716

  19. 4-Anilino-6-phenyl-quinoline inhibitors of mitogen activated protein kinase-activated protein kinase 2 (MK2).

    PubMed

    Olsson, Henric; Sjö, Peter; Ersoy, Oguz; Kristoffersson, Anna; Larsson, Joakim; Nordén, Bo

    2010-08-15

    A class of inhibitors of mitogen activated protein kinase-activated kinase 2 (MK2) was discovered via high-throughput screening. This compound class demonstrates activity against the enzyme with sub-microM IC(50) values, and suppresses LPS-induced TNFalpha levels in THP-1 cells. MK2 inhibition kinetic measurements indicated mixed binding approaching non-ATP competitive inhibition.

  20. Phosphorylation of platelet actin-binding protein during platelet activation

    SciTech Connect

    Carroll, R.C.; Gerrard, J.M.

    1982-03-01

    In this study we have followed the 32P-labeling of actin-binding protein as a function of platelet activation. Utilizing polyacrylamide-sodium dodecyl sulfate gel electrophoresis to resolve total platelet protein samples, we found 2 to 3-fold labeling increases in actin-binding protein 30 to 60 sec after thrombin stimulation. Somewhat larger increases were observed for 40,000 and 20,000 apparent molecular weight peptides. The actin-binding protein was identified on the gels by coelectrophoresis with purified actin-binding protein, its presence in cytoskeletal cores prepared by detergent extraction of activated 32P-labeled platelets, and by direct immunoprecipitation with antibodies against guinea pig vas deferens filamin (actin-binding protein). In addition, these cytoskeletal cores indicated that the 32P-labeled actin-binding protein was closely associated with the activated platelet's cytoskeleton. Following the 32P-labeling of actin-binding protein over an 8-min time course revealed that in aggregating platelet samples rapid dephosphorylation to almost initial levels occurred between 3 and 5 min. A similar curve was obtained for the 20,000 apparent molecular weight peptide. However, rapid dephosphorylation was not observed if platelet aggregation was prevented by chelating external calcium or by using thrombasthenic platelets lacking the aggregation response. Thus, cell-cell contact would seem to be crucial in initiating the rapid dephosphorylation response.

  1. Detecting protein complexes from active protein interaction networks constructed with dynamic gene expression profiles

    PubMed Central

    2013-01-01

    Background Protein interaction networks (PINs) are known to be useful to detect protein complexes. However, most available PINs are static, which cannot reflect the dynamic changes in real networks. At present, some researchers have tried to construct dynamic networks by incorporating time-course (dynamic) gene expression data with PINs. However, the inevitable background noise exists in the gene expression array, which could degrade the quality of dynamic networkds. Therefore, it is needed to filter out contaminated gene expression data before further data integration and analysis. Results Firstly, we adopt a dynamic model-based method to filter noisy data from dynamic expression profiles. Then a new method is proposed for identifying active proteins from dynamic gene expression profiles. An active protein at a time point is defined as the protein the expression level of whose corresponding gene at that time point is higher than a threshold determined by a standard variance involved threshold function. Furthermore, a noise-filtered active protein interaction network (NF-APIN) is constructed. To demonstrate the efficiency of our method, we detect protein complexes from the NF-APIN, compared with those from other dynamic PINs. Conclusion A dynamic model based method can effectively filter out noises in dynamic gene expression data. Our method to compute a threshold for determining the active time points of noise-filtered genes can make the dynamic construction more accuracy and provide a high quality framework for network analysis, such as protein complex prediction. PMID:24565281

  2. Structural mechanism of G protein activation by G protein-coupled receptor.

    PubMed

    Duc, Nguyen Minh; Kim, Hee Ryung; Chung, Ka Young

    2015-09-15

    G protein-coupled receptors (GPCRs) are a family of membrane receptors that regulate physiology and pathology of various organs. Consequently, about 40% of drugs in the market targets GPCRs. Heterotrimeric G proteins are composed of α, β, and γ subunits, and act as the key downstream signaling molecules of GPCRs. The structural mechanism of G protein activation by GPCRs has been of a great interest, and a number of biochemical and biophysical studies have been performed since the late 80's. These studies investigated the interface between GPCR and G proteins and the structural mechanism of GPCR-induced G protein activation. Recently, arrestins are also reported to be important molecular switches in GPCR-mediated signal transduction, and the physiological output of arrestin-mediated signal transduction is different from that of G protein-mediated signal transduction. Understanding the structural mechanism of the activation of G proteins and arrestins would provide fundamental information for the downstream signaling-selective GPCR-targeting drug development. This review will discuss the structural mechanism of GPCR-induced G protein activation by comparing previous biochemical and biophysical studies.

  3. Protein expression, characterization and activity comparisons of wild type and mutant DUSP5 proteins

    SciTech Connect

    Nayak, Jaladhi; Gastonguay, Adam J.; Talipov, Marat R.; Vakeel, Padmanabhan; Span, Elise A.; Kalous, Kelsey S.; Kutty, Raman G.; Jensen, Davin R.; Pokkuluri, Phani Raj; Sem, Daniel S.; Rathore, Rajendra; Ramchandran, Ramani

    2014-12-18

    Background: The mitogen-activated protein kinases (MAPKs) pathway is critical for cellular signaling, and proteins such as phosphatases that regulate this pathway are important for normal tissue development. Based on our previous work on dual specificity phosphatase-5 (DUSP5), and its role in embryonic vascular development and disease, we hypothesized that mutations in DUSP5 will affect its function. Results: In this study, we tested this hypothesis by generating full-length glutathione-S-transferase-tagged DUSP5 and serine 147 proline mutant (S147P) proteins from bacteria. Light scattering analysis, circular dichroism, enzymatic assays and molecular modeling approaches have been performed to extensively characterize the protein form and function. We demonstrate that both proteins are active and, interestingly, the S147P protein is hypoactive as compared to the DUSP5 WT protein in two distinct biochemical substrate assays. Furthermore, due to the novel positioning of the S147P mutation, we utilize computational modeling to reconstruct full-length DUSP5 and S147P to predict a possible mechanism for the reduced activity of S147P. Conclusion: Taken together, this is the first evidence of the generation and characterization of an active, full-length, mutant DUSP5 protein which will facilitate future structure-function and drug development-based studies.

  4. Protein expression, characterization and activity comparisons of wild type and mutant DUSP5 proteins

    DOE PAGES

    Nayak, Jaladhi; Gastonguay, Adam J.; Talipov, Marat R.; Vakeel, Padmanabhan; Span, Elise A.; Kalous, Kelsey S.; Kutty, Raman G.; Jensen, Davin R.; Pokkuluri, Phani Raj; Sem, Daniel S.; et al

    2014-12-18

    Background: The mitogen-activated protein kinases (MAPKs) pathway is critical for cellular signaling, and proteins such as phosphatases that regulate this pathway are important for normal tissue development. Based on our previous work on dual specificity phosphatase-5 (DUSP5), and its role in embryonic vascular development and disease, we hypothesized that mutations in DUSP5 will affect its function. Results: In this study, we tested this hypothesis by generating full-length glutathione-S-transferase-tagged DUSP5 and serine 147 proline mutant (S147P) proteins from bacteria. Light scattering analysis, circular dichroism, enzymatic assays and molecular modeling approaches have been performed to extensively characterize the protein form and function.more » We demonstrate that both proteins are active and, interestingly, the S147P protein is hypoactive as compared to the DUSP5 WT protein in two distinct biochemical substrate assays. Furthermore, due to the novel positioning of the S147P mutation, we utilize computational modeling to reconstruct full-length DUSP5 and S147P to predict a possible mechanism for the reduced activity of S147P. Conclusion: Taken together, this is the first evidence of the generation and characterization of an active, full-length, mutant DUSP5 protein which will facilitate future structure-function and drug development-based studies.« less

  5. Notum deacylates Wnt proteins to suppress signalling activity.

    PubMed

    Kakugawa, Satoshi; Langton, Paul F; Zebisch, Matthias; Howell, Steven A; Chang, Tao-Hsin; Liu, Yan; Feizi, Ten; Bineva, Ganka; O'Reilly, Nicola; Snijders, Ambrosius P; Jones, E Yvonne; Vincent, Jean-Paul

    2015-03-12

    Signalling by Wnt proteins is finely balanced to ensure normal development and tissue homeostasis while avoiding diseases such as cancer. This is achieved in part by Notum, a highly conserved secreted feedback antagonist. Notum has been thought to act as a phospholipase, shedding glypicans and associated Wnt proteins from the cell surface. However, this view fails to explain specificity, as glypicans bind many extracellular ligands. Here we provide genetic evidence in Drosophila that Notum requires glypicans to suppress Wnt signalling, but does not cleave their glycophosphatidylinositol anchor. Structural analyses reveal glycosaminoglycan binding sites on Notum, which probably help Notum to co-localize with Wnt proteins. They also identify, at the active site of human and Drosophila Notum, a large hydrophobic pocket that accommodates palmitoleate. Kinetic and mass spectrometric analyses of human proteins show that Notum is a carboxylesterase that removes an essential palmitoleate moiety from Wnt proteins and thus constitutes the first known extracellular protein deacylase. PMID:25731175

  6. Regulatory crosstalk by protein kinases on CFTR trafficking and activity

    NASA Astrophysics Data System (ADS)

    Farinha, Carlos Miguel; Swiatecka-Urban, Agnieszka; Brautigan, David; Jordan, Peter

    2016-01-01

    Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a member of the ATP binding cassette (ABC) transporter superfamily that functions as a cAMP-activated chloride ion channel in fluid-transporting epithelia. There is abundant evidence that CFTR activity (i.e. channel opening and closing) is regulated by protein kinases and phosphatases via phosphorylation and dephosphorylation. Here, we review recent evidence for the role of protein kinases in regulation of CFTR delivery to and retention in the plasma membrane. We review this information in a broader context of regulation of other transporters by protein kinases because the overall functional output of transporters involves the integrated control of both their number at the plasma membrane and their specific activity. While many details of the regulation of intracellular distribution of CFTR and other transporters remain to be elucidated, we hope that this review will motivate research providing new insights into how protein kinases control membrane transport to impact health and disease.

  7. Regulatory Crosstalk by Protein Kinases on CFTR Trafficking and Activity.

    PubMed

    Farinha, Carlos M; Swiatecka-Urban, Agnieszka; Brautigan, David L; Jordan, Peter

    2016-01-01

    Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a member of the ATP binding cassette (ABC) transporter superfamily that functions as a cAMP-activated chloride ion channel in fluid-transporting epithelia. There is abundant evidence that CFTR activity (i.e., channel opening and closing) is regulated by protein kinases and phosphatases via phosphorylation and dephosphorylation. Here, we review recent evidence for the role of protein kinases in regulation of CFTR delivery to and retention in the plasma membrane. We review this information in a broader context of regulation of other transporters by protein kinases because the overall functional output of transporters involves the integrated control of both their number at the plasma membrane and their specific activity. While many details of the regulation of intracellular distribution of CFTR and other transporters remain to be elucidated, we hope that this review will motivate research providing new insights into how protein kinases control membrane transport to impact health and disease.

  8. Regulatory Crosstalk by Protein Kinases on CFTR Trafficking and Activity

    PubMed Central

    Farinha, Carlos M.; Swiatecka-Urban, Agnieszka; Brautigan, David L.; Jordan, Peter

    2016-01-01

    Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a member of the ATP binding cassette (ABC) transporter superfamily that functions as a cAMP-activated chloride ion channel in fluid-transporting epithelia. There is abundant evidence that CFTR activity (i.e., channel opening and closing) is regulated by protein kinases and phosphatases via phosphorylation and dephosphorylation. Here, we review recent evidence for the role of protein kinases in regulation of CFTR delivery to and retention in the plasma membrane. We review this information in a broader context of regulation of other transporters by protein kinases because the overall functional output of transporters involves the integrated control of both their number at the plasma membrane and their specific activity. While many details of the regulation of intracellular distribution of CFTR and other transporters remain to be elucidated, we hope that this review will motivate research providing new insights into how protein kinases control membrane transport to impact health and disease. PMID:26835446

  9. Cellular reprogramming through mitogen-activated protein kinases

    PubMed Central

    Lee, Justin; Eschen-Lippold, Lennart; Lassowskat, Ines; Böttcher, Christoph; Scheel, Dierk

    2015-01-01

    Mitogen-activated protein kinase (MAPK) cascades are conserved eukaryote signaling modules where MAPKs, as the final kinases in the cascade, phosphorylate protein substrates to regulate cellular processes. While some progress in the identification of MAPK substrates has been made in plants, the knowledge on the spectrum of substrates and their mechanistic action is still fragmentary. In this focused review, we discuss the biological implications of the data in our original paper (Sustained mitogen-activated protein kinase activation reprograms defense metabolism and phosphoprotein profile in Arabidopsis thaliana; Frontiers in Plant Science 5: 554) in the context of related research. In our work, we mimicked in vivo activation of two stress-activated MAPKs, MPK3 and MPK6, through transgenic manipulation of Arabidopsis thaliana and used phosphoproteomics analysis to identify potential novel MAPK substrates. Here, we plotted the identified putative MAPK substrates (and downstream phosphoproteins) as a global protein clustering network. Based on a highly stringent selection confidence level, the core networks highlighted a MAPK-induced cellular reprogramming at multiple levels of gene and protein expression—including transcriptional, post-transcriptional, translational, post-translational (such as protein modification, folding, and degradation) steps, and also protein re-compartmentalization. Additionally, the increase in putative substrates/phosphoproteins of energy metabolism and various secondary metabolite biosynthesis pathways coincides with the observed accumulation of defense antimicrobial substances as detected by metabolome analysis. Furthermore, detection of protein networks in phospholipid or redox elements suggests activation of downstream signaling events. Taken in context with other studies, MAPKs are key regulators that reprogram cellular events to orchestrate defense signaling in eukaryotes. PMID:26579181

  10. Oxidative Stress Impairs the Stimulatory Effect of S100 Proteins on Protein Phosphatase 5 Activity.

    PubMed

    Yamaguchi, Fuminori; Tsuchiya, Mitsumasa; Shimamoto, Seiko; Fujimoto, Tomohito; Tokumitsu, Hiroshi; Tokuda, Masaaki; Kobayashi, Ryoji

    2016-01-01

    Oxidative stress is the consequence of an imbalance between the production of harmful reactive oxygen species and the cellular antioxidant system for neutralization, and it activates multiple intracellular signaling pathways, including apoptosis signal-regulating kinase 1 (ASK1). Protein phosphatase 5 (PP5) is a serine/threonine phosphatase involved in oxidative stress responses. Previously, we reported that S100 proteins activate PP5 in a calcium-dependent manner. S100 proteins belong to a family of small EF-hand calcium-binding proteins involved in many processes such as cell proliferation, differentiation, apoptosis, and inflammation. Therefore, we investigated the effects of oxidative stress on S100 proteins, their interaction with PP5, and PP5 enzyme activity. Recombinant S100A2 was easily air-oxidized or Cu-oxidized, and oxidized S100A2 formed cross-linked dimers and higher molecular-mass complexes. The binding of oxidized S100A2 to PP5 was reduced, resulting in decreased PP5 activation in vitro. Oxidation also impaired S100A1, S100A6, S100B, and S100P to activate PP5, although the low dose of oxidized S100 proteins still activated PP5. Hydrogen peroxide (H2O2) induced S100A2 oxidation in human keratinocytes (HaCaT) and human hepatocellular carcinoma (Huh-7) cells. Furthermore, H2O2 reduced the binding of S100A2 to PP5 and decreased PP5 activation in HaCaT and Huh-7 cells. Importantly, even the low dose of S100A2 achieved by knocking down increased dephosphorylation of ASK1 and reduced caspase 3/7 activity in Huh-7 cells treated with H2O2. These results indicate that oxidative stress impairs the ability of S100 proteins to bind and activate PP5, which in turn modulates the ASK1-mediated signaling cascades involved in apoptosis. PMID:27600583

  11. A conserved patch of hydrophobic amino acids modulates Myb activity by mediating protein-protein interactions.

    PubMed

    Dukare, Sandeep; Klempnauer, Karl-Heinz

    2016-07-01

    The transcription factor c-Myb plays a key role in the control of proliferation and differentiation in hematopoietic progenitor cells and has been implicated in the development of leukemia and certain non-hematopoietic tumors. c-Myb activity is highly dependent on the interaction with the coactivator p300 which is mediated by the transactivation domain of c-Myb and the KIX domain of p300. We have previously observed that conservative valine-to-isoleucine amino acid substitutions in a conserved stretch of hydrophobic amino acids have a profound effect on Myb activity. Here, we have explored the function of the hydrophobic region as a mediator of protein-protein interactions. We show that the hydrophobic region facilitates Myb self-interaction and binding of the histone acetyl transferase Tip60, a previously identified Myb interacting protein. We show that these interactions are affected by the valine-to-isoleucine amino acid substitutions and suppress Myb activity by interfering with the interaction of Myb and the KIX domain of p300. Taken together, our work identifies the hydrophobic region in the Myb transactivation domain as a binding site for homo- and heteromeric protein interactions and leads to a picture of the c-Myb transactivation domain as a composite protein binding region that facilitates interdependent protein-protein interactions of Myb with regulatory proteins.

  12. Organization, structure and activity of proteins in monolayers.

    PubMed

    Boucher, Julie; Trudel, Eric; Méthot, Mario; Desmeules, Philippe; Salesse, Christian

    2007-08-01

    Many different processes take place at the cell membrane interface. Indeed, for instance, ligands bind membrane proteins which in turn activate peripheral membrane proteins, some of which are enzymes whose action is also located at the membrane interface. Native cell membranes are difficult to use to gain information on the activity of individual proteins at the membrane interface because of the large number of different proteins involved in membranous processes. Model membrane systems, such as monolayers at the air-water interface, have thus been extensively used during the last 50 years to reconstitute proteins and to gain information on their organization, structure and activity in membranes. In the present paper, we review the recent work we have performed with membrane and peripheral proteins as well as enzymes in monolayers at the air-water interface. We show that the structure and orientation of gramicidin has been determined by combining different methods. Furthermore, we demonstrate that the secondary structure of rhodopsin and bacteriorhodopsin is indistinguishable from that in native membranes when appropriate conditions are used. We also show that the kinetics and extent of monolayer binding of myristoylated recoverin is much faster than that of the nonmyristoylated form and that this binding is highly favored by the presence polyunsaturated phospholipids. Moreover, we show that the use of fragments of RPE65 allow determine which region of this protein is most likely involved in membrane binding. Monomolecular films were also used to further understand the hydrolysis of organized phospholipids by phospholipases A2 and C.

  13. Anthelmintic activity of Leucaena leucocephala protein extracts on Haemonchus contortus.

    PubMed

    Soares, Alexandra Martins dos Santos; de Araújo, Sandra Alves; Lopes, Suzana Gomes; Costa Junior, Livio Martins

    2015-01-01

    The objective of this study was to evaluate the effects of protein extracts obtained from the plant Leucaena leucocephala on the nematode parasite Haemonchus contortus. The seeds, shell and cotyledon of L. leucocephala were separated and their proteins extracted using a sodium phosphate buffer, and named as TE (total seed extract), SE (shell extract) and CE (cotyledon extract). Soluble protein content, protease, protease inhibitory and chitinase activity assays were performed. Exsheathment inhibition of H. contortus larvae were performed at concentrations of 0.6 mg mL-1, and egg hatch assays were conducted at protein concentrations of 0.8, 0.4, 0.2, 0.1 and 0.05 mg mL-1. The effective concentration for 50% hatching inhibition (EC50) was estimated by probit. Different proportions of soluble proteins, protease and chitinase were found in TE and CE. Protease inhibitory activity was detected in all extracts. The EC50 of the CE and TE extracts were 0.48 and 0.33 mg mL-1, respectively. No ovicidal effects on H. contortus were detected in SE extracts, and none of the protein extracts demonstrated larvicidal effects on H. contortus. We therefore conclude that protein extracts of L. leucocephala had a detrimental effect on nematode eggs, which can be correlated with the high protease and chitinase activity of these extracts. PMID:26689178

  14. Organization, Structure and Activity of Proteins in Monolayers

    SciTech Connect

    Boucher,J.; Trudel, E.; Methot, M.; Desmeules, P.; Salesse, C.

    2007-01-01

    Many different processes take place at the cell membrane interface. Indeed, for instance, ligands bind membrane proteins which in turn activate peripheral membrane proteins, some of which are enzymes whose action is also located at the membrane interface. Native cell membranes are difficult to use to gain information on the activity of individual proteins at the membrane interface because of the large number of different proteins involved in membranous processes. Model membrane systems, such as monolayers at the air-water interface, have thus been extensively used during the last 50 years to reconstitute proteins and to gain information on their organization, structure and activity in membranes. In the present paper, we review the recent work we have performed with membrane and peripheral proteins as well as enzymes in monolayers at the air-water interface. We show that the structure and orientation of gramicidin has been determined by combining different methods. Furthermore, we demonstrate that the secondary structure of rhodopsin and bacteriorhodopsin is indistinguishable from that in native membranes when appropriate conditions are used. We also show that the kinetics and extent of monolayer binding of myristoylated recoverin is much faster than that of the nonmyristoylated form and that this binding is highly favored by the presence polyunsaturated phospholipids. Moreover, we show that the use of fragments of RPE65 allow determine which region of this protein is most likely involved in membrane binding. Monomolecular films were also used to further understand the hydrolysis of organized phospholipids by phospholipases A2 and C.

  15. Biologically active protein fragments containing specific binding regions of serum albumin or related proteins

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor)

    1998-01-01

    In accordance with the present invention, biologically active protein fragments can be constructed which contain only those specific portions of the serum albumin family of proteins such as regions known as subdomains IIA and IIIA which are primarily responsible for the binding properties of the serum albumins. The artificial serums that can be prepared from these biologically active protein fragments are advantageous in that they can be produced much more easily than serums containing the whole albumin, yet still retain all or most of the original binding potential of the full albumin proteins. In addition, since the protein fragment serums of the present invention can be made from non-natural sources using conventional recombinant DNA techniques, they are far safer than serums containing natural albumin because they do not carry the potentially harmful viruses and other contaminants that will be found in the natural substances.

  16. DNA-dependent protein phosphorylation activity in Xenopus is coupled to a Ku-like protein.

    PubMed

    Kanungo, J; Cameron, R S; Takeda, Y; Hardin, J A

    1997-10-01

    DNA-dependent protein kinase (DNA-PK) is a nuclear enzyme and functions as a serine/threonine kinase that has been well characterized in both the human and the mouse. The regulatory subunit of DNA-PK is the Ku autoantigen. To demonstrate that a Ku-like protein is present in Xenopus oocytes, we used immunoprecipitation analysis with a monoclonal antibody raised against human Ku antigen and autoimmune serum containing anti-Ku antibodies. Metabolic labeling studies indicate that the Ku-like protein is synthesized mainly in late vitellogenic oocytes. By using a specific peptide substrate for DNA-PK, we demonstrate the activity of a DNA-dependent protein kinase in oocyte extracts. The kinase activity requires the Ku-like protein, since extracts depleted of Ku protein by immunoadsorption with human anti-Ku antibodies fail to demonstrate the DNA-dependent phosphorylation activity. The increased enzyme activity in vitellogenic oocytes may be correlated to the increased levels of Ku protein observed in these oocytes compared to the pre- and early vitellogenic oocytes.

  17. Factor H-related proteins determine complement-activating surfaces.

    PubMed

    Józsi, Mihály; Tortajada, Agustin; Uzonyi, Barbara; Goicoechea de Jorge, Elena; Rodríguez de Córdoba, Santiago

    2015-06-01

    Complement factor H-related proteins (FHRs) are strongly associated with different diseases involving complement dysregulation, which suggests a major role for these proteins regulating complement activation. Because FHRs are evolutionarily and structurally related to complement inhibitor factor H (FH), the initial assumption was that the FHRs are also negative complement regulators. Whereas weak complement inhibiting activities were originally reported for these molecules, recent developments indicate that FHRs may enhance complement activation, with important implications for the role of these proteins in health and disease. We review these findings here, and propose that FHRs represent a complex set of surface recognition molecules that, by competing with FH, provide improved discrimination of self and non-self surfaces and play a central role in determining appropriate activation of the complement pathway.

  18. Energy transfer at the active sites of heme proteins

    SciTech Connect

    Dlott, D.D.; Hill, J.R.

    1995-12-31

    Experiments using a picosecond pump-probe apparatus at the Picosecond Free-electron Laser Center at Stanford University, were performed to investigate the relaxation of carbon monoxide bound to the active sites of heme proteins. The significance of these experiments is two-fold: (1) they provide detailed information about molecular dynamics occurring at the active sites of proteins; and (2) they provide insight into the nature of vibrational relaxation processes in condensed matter. Molecular engineering is used to construct various molecular systems which are studied with the FEL. We have studied native proteins, mainly myoglobin obtained from different species, mutant proteins produced by genetic engineering using recombinant DNA techniques, and a variety of model systems which mimic the structures of the active sites of native proteins, which are produced using molecular synthesis. Use of these different systems permits us to investigate how specific molecular structural changes affect dynamical processes occurring at the active sites. This research provides insight into the problems of how different species needs are fulfilled by heme proteins which have greatly different functionality, which is induced by rather small structural changes.

  19. Utilizing avidity to improve antifreeze protein activity: a type III antifreeze protein trimer exhibits increased thermal hysteresis activity.

    PubMed

    Can, Özge; Holland, Nolan B

    2013-12-01

    Antifreeze proteins (AFPs) are ice growth inhibitors that allow the survival of several species living at temperatures colder than the freezing point of their bodily fluids. AFP activity is commonly defined in terms of thermal hysteresis, which is the difference observed for the solution freezing and melting temperatures. Increasing the thermal hysteresis activity of these proteins, particularly at low concentrations, is of great interest because of their wide range of potential applications. In this study, we have designed and expressed one-, two-, and three-domain antifreeze proteins to improve thermal hysteresis activity through increased binding avidity. The three-domain type III AFP yielded significantly greater activity than the one- and two-domain proteins, reaching a thermal hysteresis of >1.6 °C at a concentration of <1 mM. To elucidate the basis of this increase, the data were fit to a multidomain protein adsorption model based on the classical Langmuir isotherm. Fits of the data to the modified isotherms yield values for the equilibrium binding constants for the adsorption of AFP to ice and indicate that protein surface coverage is proportional to thermal hysteresis activity.

  20. Gc protein (vitamin D-binding protein): Gc genotyping and GcMAF precursor activity.

    PubMed

    Nagasawa, Hideko; Uto, Yoshihiro; Sasaki, Hideyuki; Okamura, Natsuko; Murakami, Aya; Kubo, Shinichi; Kirk, Kenneth L; Hori, Hitoshi

    2005-01-01

    The Gc protein (human group-specific component (Gc), a vitamin D-binding protein or Gc globulin), has important physiological functions that include involvement in vitamin D transport and storage, scavenging of extracellular G-actin, enhancement of the chemotactic activity of C5a for neutrophils in inflammation and macrophage activation (mediated by a GalNAc-modified Gc protein (GcMAF)). In this review, the structure and function of the Gc protein is focused on especially with regard to Gc genotyping and GcMAF precursor activity. A discussion of the research strategy "GcMAF as a target for drug discovery" is included, based on our own research. PMID:16302727

  1. Fluorogen-Activating-Proteins as Universal Affinity Biosensors for Immunodetection

    PubMed Central

    Gallo, Eugenio; Vasilev, Kalin V.; Jarvik, Jonathan

    2014-01-01

    Fluorogen-activating-proteins (FAPs) are a novel platform of fluorescence biosensors utilized for protein discovery. The technology currently demands molecular manipulation methods that limit its application and adaptability. Here, we highlight an alternative approach based on universal affinity reagents for protein detection. The affinity reagents were engineered as bi-partite fusion proteins, where the specificity moiety is derived from IgG-binding proteinsProtein-A or Protein-G – and the signaling element is a FAP. In this manner, primary antibodies provide the antigenic selectivity against a desired protein in biological samples, while FAP affinity reagents target the constant region (Fc) of antibodies and provide the biosensor component of detection. Fluorescence results using various techniques indicate minimal background and high target specificity for exogenous and endogenous proteins in mammalian cells. Additionally, FAP-based affinity reagents provide enhanced properties of detection previously absent using conventional affinity systems. Distinct features explored in this report include: (1) unfixed signal wavelengths (excitation and emission) determined by the particular fluorogen chosen, (2) real-time user controlled fluorescence on-set and off-set, (3) signal wavelength substitution while performing live analysis, and (4) enhanced resistance to photobleaching. PMID:24122476

  2. Counteracting Protein Kinase Activity in the Heart: The Multiple Roles of Protein Phosphatases

    PubMed Central

    Weber, Silvio; Meyer-Roxlau, Stefanie; Wagner, Michael; Dobrev, Dobromir; El-Armouche, Ali

    2015-01-01

    Decades of cardiovascular research have shown that variable and flexible levels of protein phosphorylation are necessary to maintain cardiac function. A delicate balance between phosphorylated and dephosphorylated states of proteins is guaranteed by a complex interplay of protein kinases (PKs) and phosphatases. Serine/threonine phosphatases, in particular members of the protein phosphatase (PP) family govern dephosphorylation of the majority of these cardiac proteins. Recent findings have however shown that PPs do not only dephosphorylate previously phosphorylated proteins as a passive control mechanism but are capable to actively control PK activity via different direct and indirect signaling pathways. These control mechanisms can take place on (epi-)genetic, (post-)transcriptional, and (post-)translational levels. In addition PPs themselves are targets of a plethora of proteinaceous interaction partner regulating their endogenous activity, thus adding another level of complexity and feedback control toward this system. Finally, novel approaches are underway to achieve spatiotemporal pharmacologic control of PPs which in turn can be used to fine-tune misleaded PK activity in heart disease. Taken together, this review comprehensively summarizes the major aspects of PP-mediated PK regulation and discusses the subsequent consequences of deregulated PP activity for cardiovascular diseases in depth. PMID:26617522

  3. Peptides and proteins with antimicrobial activity.

    PubMed

    Coutinho, Henrique Douglas Melo; Lôbo, Katiuscia Menezes; Bezerra, Denise Aline Casimiro; Lôbo, Inalzuir

    2008-01-01

    The increase of microbial resistance to antibiotics has led to a continuing search for newer and more effective drugs. Antimicrobial peptides are generally found in animals, plants, and microorganisms and are of great interest to medicine, pharmacology, and the food industry. These peptides are capable of inhibiting pathogenic microorganisms. They can attack parasites, while causing little or no harm to the host cells. The defensins are peptides found in granules in the polymorphonuclear neutrophils (PMNs) and are responsible for the defense of the organism. Several animal defensins, like dermaseptin, antileukoprotease, protegrin, and others, have had their activities and efficacy tested and been shown to be effective against bacteria, fungi, and protists; there are also specific defensins from invertebrates, e.g., drosomycin and heliomicin; from plants, e.g., the types A and B; and the bacteriocins, e.g., acrocin, marcescin, etc. The aim of the present work was to compile a comprehensive bibliographic review of the diverse potentially antimicrobial peptides in an effort to systematize the current knowledge on these substances as a contribution for further researches. The currently available bibliography does not give a holistic approach on this subject. The present work intends to show that the mechanism of defense represented by defensins is promising from the perspective of its application in the treatment of infectious diseases in human, animals and plants.

  4. Heated Proteins are Still Active in a Functionalized Nanoporous Support

    SciTech Connect

    Chen, Baowei; Qi, Wen N.; Li, Xiaolin; Lei, Chenghong; Liu, Jun

    2013-07-08

    We report that even under the heated condition, the conformation and activity of a protein can be hoarded in a functionalized nanoporous support via non-covalent interaction, although the hoarded protein was not exhibiting the full protein activity, the protein released subsequently still maintained its native conformation and activity. Glucose oxidase (GOX) was spontaneously and largely entrapped in aminopropyl-functionalized mesoporous silica (NH2-FMS) at 20 oC via a dominant electrostatic interaction. Although FMS-GOX displayed 45% activity of the free enzyme in solution, the GOX released from FMS exhibited its 100% activity prior to the entrapment. Surprisingly, the released GOX from FMS still maintained 89% of its initial activity prior to the entrapment after FMS-GOX was incubated at 60 oC for 1 h prior to release, while the free GOX in solution lost nearly all activity under the same incubation. Intrinsic fluorescence emission of GOX and native electrophoresis demonstrated that the heating resulted in significant conformational changes and oligomeric structures of the free GOX, but FMS efficiently maintained the thermal stability of GOX therein and resisted the thermal denaturation and oligomeric aggregation.

  5. Staphylokinase as a Plasminogen Activator Component in Recombinant Fusion Proteins

    PubMed Central

    Szarka, S. J.; Sihota, E. G.; Habibi, H. R.; Wong, S.-L.

    1999-01-01

    The plasminogen activator staphylokinase (SAK) is a promising thrombolytic agent for treatment of myocardial infarction. It can specifically stimulate the thrombolysis of both erythrocyte-rich and platelet-rich clots. However, SAK lacks fibrin-binding and thrombin inhibitor activities, two functions which would supplement and potentially improve its thrombolytic potency. Creating a recombinant fusion protein is one approach for combining protein domains with complementary functions. To evaluate SAK for use in a translational fusion protein, both N- and C-terminal fusions to SAK were constructed by using hirudin as a fusion partner. Recombinant fusion proteins were secreted from Bacillus subtilis and purified from culture supernatants. The rate of plasminogen activation by SAK was not altered by the presence of an additional N- or C-terminal protein sequence. However, cleavage at N-terminal lysines within SAK rendered the N-terminal fusion unstable in the presence of plasmin. The results of site-directed mutagenesis of lysine 10 and lysine 11 in SAK suggested that a plasmin-resistant variant cannot be created without interfering with the plasmin processing necessary for activation of SAK. Although putative plasmin cleavage sites are located at the C-terminal end of SAK at lysine 135 and lysine 136, these sites were resistant to plasmin cleavage in vitro. Therefore, C-terminal fusions represent stable configurations for developing improved thrombolytic agents based on SAK as the plasminogen activator component. PMID:9925575

  6. Ca2+ activates human homologous recombination protein Rad51 by modulating its ATPase activity

    PubMed Central

    Bugreev, Dmitry V.; Mazin, Alexander V.

    2004-01-01

    Human Rad51 (hRad51) protein plays a key role in homologous recombination and DNA repair. hRad51 protein forms a helical filament on single-stranded DNA (ssDNA), which performs the basic steps of homologous recombination: a search for homologous double-stranded DNA (dsDNA) and DNA strand exchange. hRad51 protein possesses DNA-dependent ATPase activity; however, the role of this activity has not been understood. Our current results show that Ca2+ greatly stimulates DNA strand exchange activity of hRad51 protein. We found that Ca2+ exerts its stimulatory effect by modulating the ATPase activity of hRad51 protein. Our data demonstrate that, in the presence of Mg2+, the hRad51-ATP-ssDNA filament is quickly converted to an inactive hRad51-ADP-ssDNA form, due to relatively rapid ATP hydrolysis and slow dissociation of ADP. Ca2+ maintains the active hRad51-ATP-ssDNA filament by reducing the ATP hydrolysis rate. These findings demonstrate a crucial role of the ATPase activity in regulation of DNA strand exchange activity of hRad51 protein. This mechanism of Rad51 protein regulation by modulating its ATPase activity is evolutionarily recent; we found no such mechanism for yeast Rad51 (yRad51) protein. PMID:15226506

  7. Phytochrome activation of two nuclear genes requires cytoplasmic protein synthesis.

    PubMed Central

    Lam, E; Green, P J; Wong, M; Chua, N H

    1989-01-01

    We have investigated the effects of protein synthesis inhibitors on light-induced expression of two plant nuclear genes, Cab and rbcS, in wheat, pea and transgenic tobacco. Light activation of these two genes is very sensitive to cycloheximide, an inhibitor of cytoplasmic protein synthesis but not to chloramphenicol, an inhibitor of organellar protein synthesis. Studies with chimeric gene constructs in transgenic tobacco seedlings show that cycloheximide exerts its effect at the transcriptional level. As a control, we show that the expression of the cauliflower mosaic virus (CaMV) 35S promoter is enhanced by cycloheximide treatment, irrespective of the coding sequence used. Escape-time analyses with green wheat seedlings show that the cycloheximide block for Cab gene expression is after the primary signal transduction step linked to phytochrome photoconversion. Our results suggest that phytochrome activation of Cab and rbcS is mediated by a labile protein factor(s) synthesized on cytoplasmic ribosomes. Images PMID:2583082

  8. Endocytosis of Seven-Transmembrane RGS Protein Activates G- protein Coupled Signaling in Arabidopsis

    PubMed Central

    Urano, Daisuke; Phan, Nguyen; Jones, Janice C.; Yang, Jing; Huang, Jirong; Grigston, Jeffrey; Taylor, J. Philip; Jones, Alan M.

    2012-01-01

    Signal transduction typically begins by ligand-dependent activation of a concomitant partner which is otherwise in its resting state. However, in cases where signal activation is constitutive by default, the mechanism of regulation is unknown. The Arabidopsis thaliana heterotrimeric Gα protein self-activates without accessory proteins, and is kept in its resting state by the negative regulator, AtRGS1 (Regulator of G protein Signaling 1), which is the prototype of a seven transmembrane receptor fused with an RGS domain. Endocytosis of AtRGS1 by ligand-dependent endocytosis physically uncouples the GTPase accelerating activity of AtRGS1 from the Gα protein, permitting sustained activation. Phosphorylation of AtRGS1 by AtWNK8 kinase causes AtRGS1 endocytosis, required both for G protein-mediated sugar signaling and cell proliferation. In animals, receptor endocytosis results in signal desensitization, whereas in plants, endocytosis results in signal activation. These findings reveal how different organisms rearrange a regulatory system to result in opposite outcomes using similar phosphorylation-dependent endocytosis. PMID:22940907

  9. Beyond the zone: protein needs of active individuals.

    PubMed

    Lemon, P W

    2000-10-01

    There has been debate among athletes and nutritionists regarding dietary protein needs for centuries. Although contrary to traditional belief, recent scientific information collected on physically active individuals tends to indicate that regular exercise increases daily protein requirements; however, the precise details remain to be worked out. Based on laboratory measures, daily protein requirements are increased by perhaps as much as 100% vs. recommendations for sedentary individuals (1.6-1.8 vs. 0.8 g/kg). Yet even these intakes are much less than those reported by most athletes. This may mean that actual requirements are below what is needed to optimize athletic performance, and so the debate continues. Numerous interacting factors including energy intake, carbohydrate availability, exercise intensity, duration and type, dietary protein quality, training history, gender, age, timing of nutrient intake and the like make this topic extremely complex. Many questions remain to be resolved. At the present time, substantial data indicate that the current recommended protein intake should be adjusted upward for those who are physically active, especially in populations whose needs are elevated for other reasons, e.g., growing individuals, dieters, vegetarians, individuals with muscle disease-induced weakness and the elderly. For these latter groups, specific supplementation may be appropriate, but for most North Americans who consume a varied diet, including complete protein foods (meat, eggs, fish and dairy products), and sufficient energy the increased protein needs induced by a regular exercise program can be met in one's diet.

  10. A theoretical approach to spot active regions in antimicrobial proteins

    PubMed Central

    2009-01-01

    Background Much effort goes into identifying new antimicrobial compounds able to evade the increasing resistance of microorganisms to antibiotics. One strategy relies on antimicrobial peptides, either derived from fragments released by proteolytic cleavage of proteins or designed from known antimicrobial protein regions. Results To identify these antimicrobial determinants, we developed a theoretical approach that predicts antimicrobial proteins from their amino acid sequence in addition to determining their antimicrobial regions. A bactericidal propensity index has been calculated for each amino acid, using the experimental data reported from a high-throughput screening assay as reference. Scanning profiles were performed for protein sequences and potentially active stretches were identified by the best selected threshold parameters. The method was corroborated against positive and negative datasets. This successful approach means that we can spot active sequences previously reported in the literature from experimental data for most of the antimicrobial proteins examined. Conclusion The method presented can correctly identify antimicrobial proteins with an accuracy of 85% and a sensitivity of 90%. The method can also predict their key active regions, making this a tool for the design of new antimicrobial drugs. PMID:19906288

  11. Angiogenic activity of an Onchocerca volvulus Ancylostoma secreted protein homologue.

    PubMed

    Higazi, Tarig B; Pearlman, Eric; Whikehart, David R; Unnasch, Thomas R

    2003-06-01

    Angiogenesis is an important step in the development of ocular onchocercaisis. In previous studies, it has been demonstrated that Onchocerca volvulus homologues of the Ancylostoma secreted protein family have pronounced angiogenic activity. The overall goal of the current study was to determine if this angiogenic effect is exerted through a direct or indirect mechanism. These studies focused on one member of this family, OvASP-2, as this protein is expressed in microfilaria, the stage of the parasite that causes ocular onchocercaisis. Clones encoding truncated and full length open reading frames were expressed as fusion proteins with Escherichia coli maltose binding protein (MBP), and angiogenic activity was compared in vitro and in vivo with MBP alone. Truncated constructs expressing only the first 105 amino acids of OvASP-2 were as active as the full length protein in inducing new blood vessel formation. The full length fusion protein did not stimulate proliferation or production of vascular endothelial growth factor in vascular endothelial cells in vitro, indicating that OvASP-2 does not directly stimulate angiogenesis. Sequence analysis demonstrated that the gene encoding OvASP-2 contained five introns. Sequence comparisons of the genomic loci from West African blinding and non-blinding strains of O. volvulus revealed that some polymorphism existed among the various isolates tested. However, none of these polymorphisms could be used to differentiate the parasite strains, suggesting that qualitative variation in OvASP-2 could not explain the difference in ocular pathogenic potential of the two parasite strains.

  12. Cyclic AMP-dependent protein kinase activity in Trypanosoma cruzi.

    PubMed Central

    Ulloa, R M; Mesri, E; Esteva, M; Torres, H N; Téllez-Iñón, M T

    1988-01-01

    A cyclic AMP-dependent protein kinase activity from epimastigote forms of Trypanosoma cruzi was characterized. Cytosolic extracts were chromatographed on DEAE-cellulose columns, giving two peaks of kinase activity, which were eluted at 0.15 M- and 0.32 M-NaCl respectively. The second activity peak was stimulated by nanomolar concentrations of cyclic AMP. In addition, a cyclic AMP-binding protein co-eluted with the second kinase activity peak. Cyclic AMP-dependent protein kinase activity was further purified by gel filtration, affinity chromatography on histone-agarose and cyclic AMP-agarose, as well as by chromatography on CM-Sephadex. The enzyme ('holoenzyme') could be partially dissociated into two different components: 'catalytic' and 'regulatory'. The 'regulatory' component had specific binding for cyclic AMP, and it inhibited phosphotransferase activity of the homologous 'catalytic component' or of the 'catalytic subunit' from bovine heart. Cyclic AMP reversed these inhibitions. A 'holoenzyme preparation' was phosphorylated in the absence of exogenous phosphate acceptor and analysed by polyacrylamide-gel electrophoresis. A 56 kDa band was phosphorylated. The same preparation was analysed by Western blotting, by using polyclonal antibodies to the regulatory subunits of protein kinases type I or II. Both antibodies reacted with the 56 kDa band. Images Fig. 7. Fig. 8. PMID:2848508

  13. Hydrodynamic collective effects of active proteins in biological membranes.

    PubMed

    Koyano, Yuki; Kitahata, Hiroyuki; Mikhailov, Alexander S

    2016-08-01

    Lipid bilayers forming biological membranes are known to behave as viscous two-dimensional fluids on submicrometer scales; usually they contain a large number of active protein inclusions. Recently, it was shown [A. S. Mikhailov and R. Kapral, Proc. Natl. Acad. Sci. USA 112, E3639 (2015)PNASA60027-842410.1073/pnas.1506825112] that such active proteins should induce nonthermal fluctuating lipid flows leading to diffusion enhancement and chemotaxislike drift for passive inclusions in biomembranes. Here, a detailed analytical and numerical investigation of such effects is performed. The attention is focused on the situations when proteins are concentrated within lipid rafts. We demonstrate that passive particles tend to become attracted by active rafts and are accumulated inside them. PMID:27627343

  14. MAPK-Activated Protein Kinases (MKs): Novel Insights and Challenges.

    PubMed

    Gaestel, Matthias

    2015-01-01

    Downstream of MAPKs, such as classical/atypical ERKs and p38 MAPKs, but not of JNKs, signaling is often mediated by protein kinases which are phosphorylated and activated by MAPKs and, therefore, designated MAPK-activated protein kinases (MAPKAPKs). Recently, novel insights into the specificity of the assembly of MAPK/MAPKAPK hetero-dimeric protein kinase signaling complexes have been gained. In addition, new functional aspects of MKs have been described and established functions have been challenged. This short review will summarize recent developments including the linear motif (LM) in MKs, the ERK-independent activation of RSK, the RSK-independent effects of some RSK-inhibitors and the challenged role of MK5/PRAK in tumor suppression. PMID:26779481

  15. Sterol carrier protein2-like activity in rat intestine.

    PubMed

    Kharroubi, A; Wadsworth, J A; Chanderbhan, R; Wiesenfeld, P; Noland, B; Scallen, T; Vahouny, G V; Gallo, L L

    1988-03-01

    A sterol carrier protein2 (SCP2)-like activity has been demonstrated in rat intestinal mucosal homogenates and in isolated intestinal cells from both crypt and villus zones. The results indicate the presence of a protein with similar molecular weight and antigenicity to that of authentic SCP2 purified from rat liver cytosol. Like liver SCP2, mucosal cytosol stimulates pregnenolone production in rat adrenal mitochondria and acyl coenzyme A:cholesterol acyltransferase activity of liver and mucosal microsomes. The distribution of SCP2-like activity as determined by radioimmunoassay indicates high levels in mitochondria and cytosol and relatively lower levels in microsomes and in brush-border membranes. The widespread distribution of SCP2-like protein in the intestine is consistent with potential transfer functions in all phases of cholesterol processing. PMID:3379341

  16. Hydrodynamic collective effects of active proteins in biological membranes

    NASA Astrophysics Data System (ADS)

    Koyano, Yuki; Kitahata, Hiroyuki; Mikhailov, Alexander S.

    2016-08-01

    Lipid bilayers forming biological membranes are known to behave as viscous two-dimensional fluids on submicrometer scales; usually they contain a large number of active protein inclusions. Recently, it was shown [A. S. Mikhailov and R. Kapral, Proc. Natl. Acad. Sci. USA 112, E3639 (2015), 10.1073/pnas.1506825112] that such active proteins should induce nonthermal fluctuating lipid flows leading to diffusion enhancement and chemotaxislike drift for passive inclusions in biomembranes. Here, a detailed analytical and numerical investigation of such effects is performed. The attention is focused on the situations when proteins are concentrated within lipid rafts. We demonstrate that passive particles tend to become attracted by active rafts and are accumulated inside them.

  17. Signal peptides are allosteric activators of the protein translocase

    PubMed Central

    Gouridis, Giorgos; Karamanou, Spyridoula; Gelis, Ioannis; Kalodimos, Charalampos G.; Economou, Anastassios

    2010-01-01

    Extra-cytoplasmic polypeptides are usually synthesized as “preproteins” carrying aminoterminal, cleavable signal peptides1 and secreted across membranes by translocases. The main bacterial translocase comprises the SecYEG protein-conducting channel and the peripheral ATPase motor SecA2,3. Most proteins destined for the periplasm and beyond are exported post-translationally by SecA2,3. Preprotein targeting to SecA is thought to involve signal peptides4 and chaperones like SecB5,6. Here we reveal that signal peptides have a novel role beyond targeting: they are essential allosteric activators of the translocase. Upon docking on their binding groove on SecA, signal peptides act in trans to drive three successive states: first, “triggering” that drives the translocase to a lower activation energy state; then “trapping” that engages non-native preprotein mature domains docked with high affinity on the secretion apparatus and, finally, “secretion” during which trapped mature domains undergo multiple turnovers of translocation in segments7. A significant contribution by mature domains renders signal peptides less critical in bacterial secretory protein targeting than currently assumed. Rather, it is their function as allosteric activators of the translocase that renders signal peptides essential for protein secretion. A role for signal peptides and targeting sequences as allosteric activators may be universal in protein translocases. PMID:19924216

  18. Complement activation and protein adsorption by carbon nanotubes.

    PubMed

    Salvador-Morales, Carolina; Flahaut, Emmanuel; Sim, Edith; Sloan, Jeremy; Green, Malcolm L H; Sim, Robert B

    2006-02-01

    As a first step to validate the use of carbon nanotubes as novel vaccine or drug delivery devices, their interaction with a part of the human immune system, complement, has been explored. Haemolytic assays were conducted to investigate the activation of the human serum complement system via the classical and alternative pathways. Western blot and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) techniques were used to elucidate the mechanism of activation of complement via the classical pathway, and to analyse the interaction of complement and other plasma proteins with carbon nanotubes. We report for the first time that carbon nanotubes activate human complement via both classical and alternative pathways. We conclude that complement activation by nanotubes is consistent with reported adjuvant effects, and might also in various circumstances promote damaging effects of excessive complement activation, such as inflammation and granuloma formation. C1q binds directly to carbon nanotubes. Protein binding to carbon nanotubes is highly selective, since out of the many different proteins in plasma, very few bind to the carbon nanotubes. Fibrinogen and apolipoproteins (AI, AIV and CIII) were the proteins that bound to carbon nanotubes in greatest quantity.

  19. L-Alanylglutamine inhibits signaling proteins that activate protein degradation, but does not affect proteins that activate protein synthesis after an acute resistance exercise.

    PubMed

    Wang, Wanyi; Choi, Ran Hee; Solares, Geoffrey J; Tseng, Hung-Min; Ding, Zhenping; Kim, Kyoungrae; Ivy, John L

    2015-07-01

    Sustamine™ (SUS) is a dipeptide composed of alanine and glutamine (AlaGln). Glutamine has been suggested to increase muscle protein accretion; however, the underlying molecular mechanisms of glutamine on muscle protein metabolism following resistance exercise have not been fully addressed. In the present study, 2-month-old rats climbed a ladder 10 times with a weight equal to 75 % of their body mass attached at the tail. Rats were then orally administered one of four solutions: placebo (PLA-glycine = 0.52 g/kg), whey protein (WP = 0.4 g/kg), low dose of SUS (LSUS = 0.1 g/kg), or high dose of SUS (HSUS = 0.5 g/kg). An additional group of sedentary (SED) rats was intubated with glycine (0.52 g/kg) at the same time as the ladder-climbing rats. Blood samples were collected immediately after exercise and at either 20 or 40 min after recovery. The flexor hallucis longus (FHL), a muscle used for climbing, was excised at 20 or 40 min post exercise and analyzed for proteins regulating protein synthesis and degradation. All supplements elevated the phosphorylation of FOXO3A above SED at 20 min post exercise, but only the SUS supplements significantly reduced the phosphorylation of AMPK and NF-kB p65. SUS supplements had no effect on mTOR signaling, but WP supplementation yielded a greater phosphorylation of mTOR, p70S6k, and rpS6 compared with PLA at 20 min post exercise. However, by 40 min post exercise, phosphorylation of mTOR and rpS6 in PLA had risen to levels not different than WP. These results suggest that SUS blocks the activation of intracellular signals for MPB, whereas WP accelerates mRNA translation.

  20. Methods to distinguish various types of protein phosphatase activity

    SciTech Connect

    Brautigan, D.L.; Shriner, C.L.

    1988-01-01

    To distinguish the action of protein Tyr(P) and protein Ser(P)/Thr(P) phosphatases on /sup 32/P-labeled phosphoproteins in subcellular fractions different inhibitors and activators are utilized. Comparison of the effects of added compounds provides a convenient, indirect method to characterize dephosphorylation reactions. Protein Tyr(P) phosphatases are specifically inhibited by micromolar Zn2+ or vanadate, and show maximal activity in the presence of EDTA. The other class of cellular phosphatases, specific for protein Ser(P) and Thr(P) residues, are inhibited by fluoride and EDTA. In this class of enzymes two major functional types can be distinguished: those sensitive to inhibition by the heat-stable protein inhibitor-2 and not stimulated by polycations, and those not sensitive to inhibition and stimulated by polycations. Preparation of /sup 32/P-labeled Tyr(P) and Ser(P) phosphoproteins also is presented for the direct measurement of phosphatase activities in preparations by the release of acid-soluble (/sup 32/P)phosphate.

  1. Actions of Rho family small G proteins and p21-activated protein kinases on mitogen-activated protein kinase family members.

    PubMed Central

    Frost, J A; Xu, S; Hutchison, M R; Marcus, S; Cobb, M H

    1996-01-01

    The mitogen-activated protein (MAP) kinases are a family of serine/threonine kinases that are regulated by distinct extracellular stimuli. The currently known members include extracellular signal-regulated protein kinase 1 (ERK1), ERK2, the c-Jun N-terminal kinase/stress-activated protein kinases (JNK/SAPKs), and p38 MAP kinases. We find that overexpression of the Ste20-related enzymes p21-activated kinase 1 (PAK1) and PAK2 in 293 cells is sufficient to activate JNK/SAPK and to a lesser extent p38 MAP kinase but not ERK2. Rat MAP/ERK kinase kinase 1 can stimulate the activity of each of these MAP kinases. Although neither activated Rac nor the PAKs stimulate ERK2 activity, overexpression of either dominant negative Rac2 or the N-terminal regulatory domain of PAK1 inhibits Ras-mediated activation of ERK2, suggesting a permissive role for Rac in the control of the ERK pathway. Furthermore, constitutively active Rac2, Cdc42hs, and RhoA synergize with an activated form of Raf to increase ERK2 activity. These findings reveal a previously unrecognized connection between Rho family small G proteins and the ERK pathway. PMID:8668187

  2. AMP-activated protein kinase and metabolic control

    PubMed Central

    Viollet, Benoit; Andreelli, Fabrizio

    2011-01-01

    AMP-activated protein kinase (AMPK), a phylogenetically conserved serine/threonine protein kinase, is a major regulator of cellular and whole-body energy homeostasis that coordinates metabolic pathways in order to balance nutrient supply with energy demand. It is now recognized that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profile and blood pressure in insulin-resistant rodents. Indeed, AMPK activation mimics the beneficial effects of physical activity or those of calorie restriction by acting on multiple cellular targets. In addition it is now demonstrated that AMPK is one of the probable (albeit indirect) targets of major antidiabetic drugs including, the biguanides (metformin) and thiazolidinediones, as well as of insulin sensitizing adipokines (e.g., adiponectin). Taken together, such findings highlight the logic underlying the concept of targeting the AMPK pathway for the treatment of metabolic syndrome and type 2 diabetes. PMID:21484577

  3. Detergent activation of the binding protein in the folate radioassay

    SciTech Connect

    Hansen, S.I.; Holm, J.; Lyngbye, J.

    1982-01-01

    A minor cow's whey protein associated with ..beta..-lactoglobulin is used as binding protein in the competitive radioassay for serum and erythrocyte folate. Seeking to optimize the assay, we tested the performance of binder solutions of increasing purity. The folate binding protein was isolated from cow's whey by means of CM-Sepharose CL-6B cation-exchange chromatography, and further purified on a methotrexate-AH-Sepharose 4B affinity matrix. In contrast to ..beta..-lactoglobulin, the purified protein did not bind folate unless the detergents cetyltrimethylammonium (10 mmol/Ll) or Triton X-100 (1 g/L) were present. Such detergent activation was not needed in the presence of serum. There seems to be a striking analogy between these phenomena and the well-known reactivation of certain purified membrane-derived enzymes by surfactants (lipids/detergents).

  4. Controlling Protein Activity and Degradation Using Blue Light.

    PubMed

    Lutz, Anne P; Renicke, Christian; Taxis, Christof

    2016-01-01

    Regulation of protein stability is a fundamental process in eukaryotic cells and pivotal to, e.g., cell cycle progression, faithful chromosome segregation, or protein quality control. Synthetic regulation of protein stability requires conditional degradation sequences (degrons) that induce a stability switch upon a specific signal. Fusion to a selected target protein permits to influence virtually every process in a cell. Light as signal is advantageous due to its precise applicability in time, space, quality, and quantity. Light control of protein stability was achieved by fusing the LOV2 photoreceptor domain of Arabidopsis thaliana phototropin1 with a synthetic degron (cODC1) derived from the carboxy-terminal degron of ornithine decarboxylase to obtain the photosensitive degron (psd) module. The psd module can be attached to the carboxy terminus of target proteins that are localized to the cytosol or nucleus to obtain light control over their stability. Blue light induces structural changes in the LOV2 domain, which in turn lead to activation of the degron and thus proteasomal degradation of the whole fusion protein. Variants of the psd module with diverse characteristics are useful to fine-tune the stability of a selected target at permissive (darkness) and restrictive conditions (blue light). PMID:26965116

  5. Altered Activation of Protein Kinase PKR and Enhanced Apoptosis in Dystonia Cells Carrying a Mutation in PKR Activator Protein PACT*

    PubMed Central

    Vaughn, Lauren S; Bragg, D. Cristopher; Sharma, Nutan; Camargos, Sarah; Cardoso, Francisco; Patel, Rekha C

    2015-01-01

    PACT is a stress-modulated activator of the interferon-induced double-stranded RNA-activated protein kinase (PKR). Stress-induced phosphorylation of PACT is essential for PACT's association with PKR leading to PKR activation. PKR activation leads to phosphorylation of translation initiation factor eIF2α inhibition of protein synthesis and apoptosis. A recessively inherited form of early-onset dystonia DYT16 has been recently identified to arise due to a homozygous missense mutation P222L in PACT. To examine if the mutant P222L protein alters the stress-response pathway, we examined the ability of mutant P222L to interact with and activate PKR. Our results indicate that the substitution mutant P222L activates PKR more robustly and for longer duration albeit with slower kinetics in response to the endoplasmic reticulum stress. In addition, the affinity of PACT-PACT and PACT-PKR interactions is enhanced in dystonia patient lymphoblasts, thereby leading to intensified PKR activation and enhanced cellular death. P222L mutation also changes the affinity of PACT-TRBP interaction after cellular stress, thereby offering a mechanism for the delayed PKR activation in response to stress. Our results demonstrate the impact of a dystonia-causing substitution mutation on stress-induced cellular apoptosis. PMID:26231208

  6. Steroidogenic Acute Regulatory Protein Overexpression Correlates with Protein Kinase A Activation in Adrenocortical Adenoma

    PubMed Central

    Xie, Jing; Su, Tingwei; Jiang, Lei; Jiang, Yiran; Cao, Yanan; Liu, Jianmin; Ning, Guang; Wang, Weiqing

    2016-01-01

    The association of pathological features of cortisol-producing adrenocortical adenomas (ACAs) with somatic driver mutations and their molecular classification remain unclear. In this study, we explored the association between steroidogenic acute regulatory protein (StAR) expression and the driver mutations activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling to identify the pathological markers of ACAs. Immunohistochemical staining for StAR and mutations in the protein kinase cAMP-activated catalytic subunit alpha (PRKACA), protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) and guanine nucleotide binding protein, alpha stimulating (GNAS) genes were examined in 97 ACAs. The association of StAR expression with the clinical and mutational features of the ACAs was analyzed. ACAs with mutations in PRKACA, GNAS, and PRKAR1A showed strong immunopositive staining for StAR. The concordance between high StAR expression and mutations activating cAMP/PKA signaling in the ACAs was 99.0%. ACAs with high expression of StAR had significantly smaller tumor volume (P < 0.001) and higher urinary cortisol per tumor volume (P = 0.032) than those with low expression of StAR. Our findings suggest that immunohistochemical staining for StAR is a reliable pathological approach for the diagnosis and classification of ACAs with cAMP/PKA signaling-activating mutations. PMID:27606678

  7. Steroidogenic Acute Regulatory Protein Overexpression Correlates with Protein Kinase A Activation in Adrenocortical Adenoma.

    PubMed

    Zhou, Weiwei; Wu, Luming; Xie, Jing; Su, Tingwei; Jiang, Lei; Jiang, Yiran; Cao, Yanan; Liu, Jianmin; Ning, Guang; Wang, Weiqing

    2016-01-01

    The association of pathological features of cortisol-producing adrenocortical adenomas (ACAs) with somatic driver mutations and their molecular classification remain unclear. In this study, we explored the association between steroidogenic acute regulatory protein (StAR) expression and the driver mutations activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling to identify the pathological markers of ACAs. Immunohistochemical staining for StAR and mutations in the protein kinase cAMP-activated catalytic subunit alpha (PRKACA), protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) and guanine nucleotide binding protein, alpha stimulating (GNAS) genes were examined in 97 ACAs. The association of StAR expression with the clinical and mutational features of the ACAs was analyzed. ACAs with mutations in PRKACA, GNAS, and PRKAR1A showed strong immunopositive staining for StAR. The concordance between high StAR expression and mutations activating cAMP/PKA signaling in the ACAs was 99.0%. ACAs with high expression of StAR had significantly smaller tumor volume (P < 0.001) and higher urinary cortisol per tumor volume (P = 0.032) than those with low expression of StAR. Our findings suggest that immunohistochemical staining for StAR is a reliable pathological approach for the diagnosis and classification of ACAs with cAMP/PKA signaling-activating mutations.

  8. Steroidogenic Acute Regulatory Protein Overexpression Correlates with Protein Kinase A Activation in Adrenocortical Adenoma.

    PubMed

    Zhou, Weiwei; Wu, Luming; Xie, Jing; Su, Tingwei; Jiang, Lei; Jiang, Yiran; Cao, Yanan; Liu, Jianmin; Ning, Guang; Wang, Weiqing

    2016-01-01

    The association of pathological features of cortisol-producing adrenocortical adenomas (ACAs) with somatic driver mutations and their molecular classification remain unclear. In this study, we explored the association between steroidogenic acute regulatory protein (StAR) expression and the driver mutations activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling to identify the pathological markers of ACAs. Immunohistochemical staining for StAR and mutations in the protein kinase cAMP-activated catalytic subunit alpha (PRKACA), protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) and guanine nucleotide binding protein, alpha stimulating (GNAS) genes were examined in 97 ACAs. The association of StAR expression with the clinical and mutational features of the ACAs was analyzed. ACAs with mutations in PRKACA, GNAS, and PRKAR1A showed strong immunopositive staining for StAR. The concordance between high StAR expression and mutations activating cAMP/PKA signaling in the ACAs was 99.0%. ACAs with high expression of StAR had significantly smaller tumor volume (P < 0.001) and higher urinary cortisol per tumor volume (P = 0.032) than those with low expression of StAR. Our findings suggest that immunohistochemical staining for StAR is a reliable pathological approach for the diagnosis and classification of ACAs with cAMP/PKA signaling-activating mutations. PMID:27606678

  9. Installing hydrolytic activity into a completely de novo protein framework

    NASA Astrophysics Data System (ADS)

    Burton, Antony J.; Thomson, Andrew R.; Dawson, William M.; Brady, R. Leo; Woolfson, Derek N.

    2016-09-01

    The design of enzyme-like catalysts tests our understanding of sequence-to-structure/function relationships in proteins. Here we install hydrolytic activity predictably into a completely de novo and thermostable α-helical barrel, which comprises seven helices arranged around an accessible channel. We show that the lumen of the barrel accepts 21 mutations to functional polar residues. The resulting variant, which has cysteine-histidine-glutamic acid triads on each helix, hydrolyses p-nitrophenyl acetate with catalytic efficiencies that match the most-efficient redesigned hydrolases based on natural protein scaffolds. This is the first report of a functional catalytic triad engineered into a de novo protein framework. The flexibility of our system also allows the facile incorporation of unnatural side chains to improve activity and probe the catalytic mechanism. Such a predictable and robust construction of truly de novo biocatalysts holds promise for applications in chemical and biochemical synthesis.

  10. Installing hydrolytic activity into a completely de novo protein framework

    NASA Astrophysics Data System (ADS)

    Burton, Antony J.; Thomson, Andrew R.; Dawson, William M.; Brady, R. Leo; Woolfson, Derek N.

    2016-09-01

    The design of enzyme-like catalysts tests our understanding of sequence-to-structure/function relationships in proteins. Here we install hydrolytic activity predictably into a completely de novo and thermostable α-helical barrel, which comprises seven helices arranged around an accessible channel. We show that the lumen of the barrel accepts 21 mutations to functional polar residues. The resulting variant, which has cysteine–histidine–glutamic acid triads on each helix, hydrolyses p-nitrophenyl acetate with catalytic efficiencies that match the most-efficient redesigned hydrolases based on natural protein scaffolds. This is the first report of a functional catalytic triad engineered into a de novo protein framework. The flexibility of our system also allows the facile incorporation of unnatural side chains to improve activity and probe the catalytic mechanism. Such a predictable and robust construction of truly de novo biocatalysts holds promise for applications in chemical and biochemical synthesis.

  11. Installing hydrolytic activity into a completely de novo protein framework.

    PubMed

    Burton, Antony J; Thomson, Andrew R; Dawson, William M; Brady, R Leo; Woolfson, Derek N

    2016-09-01

    The design of enzyme-like catalysts tests our understanding of sequence-to-structure/function relationships in proteins. Here we install hydrolytic activity predictably into a completely de novo and thermostable α-helical barrel, which comprises seven helices arranged around an accessible channel. We show that the lumen of the barrel accepts 21 mutations to functional polar residues. The resulting variant, which has cysteine-histidine-glutamic acid triads on each helix, hydrolyses p-nitrophenyl acetate with catalytic efficiencies that match the most-efficient redesigned hydrolases based on natural protein scaffolds. This is the first report of a functional catalytic triad engineered into a de novo protein framework. The flexibility of our system also allows the facile incorporation of unnatural side chains to improve activity and probe the catalytic mechanism. Such a predictable and robust construction of truly de novo biocatalysts holds promise for applications in chemical and biochemical synthesis. PMID:27554410

  12. Protein kinase A activity and Hedgehog signaling pathway.

    PubMed

    Kotani, Tomoya

    2012-01-01

    Protein kinase A (PKA) is a well-known kinase that plays fundamental roles in a variety of biological processes. In Hedgehog-responsive cells, PKA plays key roles in proliferation and fate specification by modulating the transduction of Hedgehog signaling. In the absence of Hedgehog, a basal level of PKA activity represses the transcription of Hedgehog target genes. The main substrates of PKA in this process are the Ci/Gli family of bipotential transcription factors, which activate and repress Hedgehog target gene expression. PKA phosphorylates Ci/Gli, promoting the production of the repressor forms of Ci/Gli and thus repressing Hedgehog target gene expression. In contrast, the activation of Hedgehog signaling in response to Hedgehog increases the active forms of Ci/Gli, resulting in Hedgehog target gene expression. Because both decreased and increased levels of PKA activity cause abnormal cell proliferation and alter cell fate specification, the basal level of PKA activity in Hedgehog-responsive cells should be precisely regulated. However, the mechanism by which PKA activity is regulated remains obscure and appears to vary between cell types, tissues, and organisms. To date, two mechanisms have been proposed. One is a classical mechanism in which PKA activity is regulated by a small second messenger, cAMP; the other is a novel mechanism in which PKA activity is regulated by a protein, Misty somites. PMID:22391308

  13. Monitoring Brain Activity with Protein Voltage and Calcium Sensors

    PubMed Central

    Storace, Douglas A.; Braubach, Oliver R.; Jin, Lei; Cohen, Lawrence B.; Sung, Uhna

    2015-01-01

    Understanding the roles of different cell types in the behaviors generated by neural circuits requires protein indicators that report neural activity with high spatio-temporal resolution. Genetically encoded fluorescent protein (FP) voltage sensors, which optically report the electrical activity in distinct cell populations, are, in principle, ideal candidates. Here we demonstrate that the FP voltage sensor ArcLight reports odor-evoked electrical activity in the in vivo mammalian olfactory bulb in single trials using both wide-field and 2-photon imaging. ArcLight resolved fast odorant-responses in individual glomeruli, and distributed odorant responses across a population of glomeruli. Comparisons between ArcLight and the protein calcium sensors GCaMP3 and GCaMP6f revealed that ArcLight had faster temporal kinetics that more clearly distinguished activity elicited by individual odorant inspirations. In contrast, the signals from both GCaMPs were a saturating integral of activity that returned relatively slowly to the baseline. ArcLight enables optical electrophysiology of mammalian neuronal population activity in vivo. PMID:25970202

  14. Monitoring brain activity with protein voltage and calcium sensors.

    PubMed

    Storace, Douglas A; Braubach, Oliver R; Jin, Lei; Cohen, Lawrence B; Sung, Uhna

    2015-05-13

    Understanding the roles of different cell types in the behaviors generated by neural circuits requires protein indicators that report neural activity with high spatio-temporal resolution. Genetically encoded fluorescent protein (FP) voltage sensors, which optically report the electrical activity in distinct cell populations, are, in principle, ideal candidates. Here we demonstrate that the FP voltage sensor ArcLight reports odor-evoked electrical activity in the in vivo mammalian olfactory bulb in single trials using both wide-field and 2-photon imaging. ArcLight resolved fast odorant-responses in individual glomeruli, and distributed odorant responses across a population of glomeruli. Comparisons between ArcLight and the protein calcium sensors GCaMP3 and GCaMP6f revealed that ArcLight had faster temporal kinetics that more clearly distinguished activity elicited by individual odorant inspirations. In contrast, the signals from both GCaMPs were a saturating integral of activity that returned relatively slowly to the baseline. ArcLight enables optical electrophysiology of mammalian neuronal population activity in vivo.

  15. Protein synthesis inhibitors reveal differential regulation of mitogen-activated protein kinase and stress-activated protein kinase pathways that converge on Elk-1.

    PubMed Central

    Zinck, R; Cahill, M A; Kracht, M; Sachsenmaier, C; Hipskind, R A; Nordheim, A

    1995-01-01

    Inhibitors of protein synthesis, such as anisomycin and cycloheximide, lead to superinduction of immediate-early genes. We demonstrate that these two drugs activate intracellular signaling pathways involving both the mitogen-activated protein kinase (MAPK) and stress-activated protein kinase (SAPK) cascades. The activation of either pathway correlates with phosphorylation of the c-fos regulatory transcription factor Elk-1. In HeLa cells, anisomycin stabilizes c-fos mRNA when protein synthesis is inhibited to only 50%. Under these conditions, anisomycin, in contrast to cycloheximide, rapidly induces kinase activation and efficient Elk-1 phosphorylation. However, full inhibition of translation by either drug leads to prolonged activation of SAPK activity, while MAPK induction is transient. This correlates with prolonged Elk-1 phosphorylation and c-fos transcription. Elk-1 induction and c-fos activation are also observed in KB cells, in which anisomycin strongly induces SAPKs but not MAPKs. Purified p54 SAPK alpha efficiently phosphorylates the Elk-1 C-terminal domain in vitro and comigrates with anisomycin-activated kinases in in-gel kinase assays. Thus, Elk-1 provides a potential convergence point for the MAPK and SAPK signaling pathways. The activation of signal cascades and control of transcription factor function therefore represent prominent processes in immediate-early gene superinduction. PMID:7651411

  16. Immersion freezing of ice nucleating active protein complexes

    NASA Astrophysics Data System (ADS)

    Hartmann, S.; Augustin, S.; Clauss, T.; Voigtländer, J.; Niedermeier, D.; Wex, H.; Stratmann, F.

    2012-08-01

    Biological particles, e.g. bacteria and their Ice Nucleating Active (INA) protein complexes, might play an important role for the ice formation in atmospheric mixed-phase clouds. Therefore, the immersion freezing behavior of INA protein complexes generated from a SnomaxTM solution/suspension was investigated as function of temperature in a range of -5 °C to -38 °C at the Leipzig Aerosol Cloud Interaction Simulator (LACIS). The immersion freezing of droplets containing small numbers of INA protein complexes occurs in a temperature range of -7 °C and -10 °C. The experiments performed in the lower temperature range, where all droplets freeze which contain at least one INA protein complex, are used to determine the average number of INA protein complexes present, assuming that the INA protein complexes are Poisson distributed over the droplet ensemble. Knowing the average number of INA protein complexes, the heterogeneous ice nucleation rate and rate coefficient of a single INA protein complex is determined by using the newly-developed CHESS model (stoCHastic model of idEntical poiSSon distributed ice nuclei). Therefore, we assume the ice nucleation process to be of stochastic nature, and a parameterization of the INA protein complex's nucleation rate. Analyzing the results of immersion freezing experiments from literature (SnomaxTM and Pseudomonas syringae bacteria), to results gained in this study, demonstrates that first, a similar temperature dependence of the heterogeneous ice nucleation rate for a single INA protein complex was found in all experiments, second, the shift of the ice fraction curves to higher temperatures can be explained consistently by a higher average number of INA protein complexes being present in the droplet ensemble, and finally the heterogeneous ice nucleation rate of one single INA protein complex might be also applicable for intact Pseudomonas syringae bacteria cells. The results obtained in this study allow a new perspective on the

  17. Activation of immobilized, biotinylated choleragen AI protein by a 19-kilodalton guanine nucleotide-binding protein.

    PubMed

    Noda, M; Tsai, S C; Adamik, R; Bobak, D A; Moss, J; Vaughan, M

    1989-09-19

    Cholera toxin catalyzes the ADP-ribosylation that results in activation of the stimulatory guanine nucleotide-binding protein of the adenylyl cyclase system, known as Gs. The toxin also ADP-ribosylates other proteins and simple guanidino compounds and auto-ADP-ribosylates its AI protein (CTA1). All of the ADP-ribosyltransferase activities of CTAI are enhanced by 19-21-kDa guanine nucleotide-binding proteins known as ADP-ribosylation factors, or ARFs. CTAI contains a single cysteine located near the carboxy terminus. CTAI was immobilized through this cysteine by reaction with iodoacetyl-N-biotinyl-hexylenediamine and binding of the resulting biotinylated protein to avidin-agarose. Immobilized CTAI catalyzed the ARF-stimulated ADP-ribosylation of agmatine. The reaction was enhanced by detergents and phospholipid, but the fold stimulation by purified sARF-II from bovine brain was considerably less than that observed with free CTA. ADP-ribosylation of Gsa by immobilized CTAI, which was somewhat enhanced by sARF-II, was much less than predicted on the basis of the NAD:agmatine ADP-ribosyltransferase activity. Immobilized CTAI catalyzed its own auto-ADP-ribosylation as well as the ADP-ribosylation of the immobilized avidin and CTA2, with relatively little stimulation by sARF-II. ADP-ribosylation of CTA2 by free CTAI is minimal. These observations are consistent with the conclusion that the cysteine near the carboxy terminus of the toxin is not critical for ADP-ribosyltransferase activity or for its regulation by sARF-II. Biotinylation and immobilization of the toxin through this cysteine may, however, limit accessibility to Gsa or SARF-II, or perhaps otherwise reduce interaction with these proteins whether as substrates or activator.

  18. Reassessing the Potential Activities of Plant CGI-58 Protein

    PubMed Central

    Khatib, Abdallah; Arhab, Yani; Bentebibel, Assia; Abousalham, Abdelkarim; Noiriel, Alexandre

    2016-01-01

    Comparative Gene Identification-58 (CGI-58) is a widespread protein found in animals and plants. This protein has been shown to participate in lipolysis in mice and humans by activating Adipose triglyceride lipase (ATGL), the initial enzyme responsible for the triacylglycerol (TAG) catabolism cascade. Human mutation of CGI-58 is the cause of Chanarin-Dorfman syndrome, an orphan disease characterized by a systemic accumulation of TAG which engenders tissue disorders. The CGI-58 protein has also been shown to participate in neutral lipid metabolism in plants and, in this case, a mutation again provokes TAG accumulation. Although its roles as an ATGL coactivator and in lipid metabolism are quite clear, the catalytic activity of CGI-58 is still in question. The acyltransferase activities of CGI-58 have been speculated about, reported or even dismissed and experimental evidence that CGI-58 expressed in E. coli possesses an unambiguous catalytic activity is still lacking. To address this problem, we developed a new set of plasmids and site-directed mutants to elucidate the in vivo effects of CGI-58 expression on lipid metabolism in E. coli. By analyzing the lipid composition in selected E. coli strains expressing CGI-58 proteins, and by reinvestigating enzymatic tests with adequate controls, we show here that recombinant plant CGI-58 has none of the proposed activities previously described. Recombinant plant and mouse CGI-58 both lack acyltransferase activity towards either lysophosphatidylglycerol or lysophosphatidic acid to form phosphatidylglycerol or phosphatidic acid and recombinant plant CGI-58 does not catalyze TAG or phospholipid hydrolysis. However, expression of recombinant plant CGI-58, but not mouse CGI-58, led to a decrease in phosphatidylglycerol in all strains of E. coli tested, and a mutation of the putative catalytic residues restored a wild-type phenotype. The potential activities of plant CGI-58 are subsequently discussed. PMID:26745266

  19. Reassessing the Potential Activities of Plant CGI-58 Protein.

    PubMed

    Khatib, Abdallah; Arhab, Yani; Bentebibel, Assia; Abousalham, Abdelkarim; Noiriel, Alexandre

    2016-01-01

    Comparative Gene Identification-58 (CGI-58) is a widespread protein found in animals and plants. This protein has been shown to participate in lipolysis in mice and humans by activating Adipose triglyceride lipase (ATGL), the initial enzyme responsible for the triacylglycerol (TAG) catabolism cascade. Human mutation of CGI-58 is the cause of Chanarin-Dorfman syndrome, an orphan disease characterized by a systemic accumulation of TAG which engenders tissue disorders. The CGI-58 protein has also been shown to participate in neutral lipid metabolism in plants and, in this case, a mutation again provokes TAG accumulation. Although its roles as an ATGL coactivator and in lipid metabolism are quite clear, the catalytic activity of CGI-58 is still in question. The acyltransferase activities of CGI-58 have been speculated about, reported or even dismissed and experimental evidence that CGI-58 expressed in E. coli possesses an unambiguous catalytic activity is still lacking. To address this problem, we developed a new set of plasmids and site-directed mutants to elucidate the in vivo effects of CGI-58 expression on lipid metabolism in E. coli. By analyzing the lipid composition in selected E. coli strains expressing CGI-58 proteins, and by reinvestigating enzymatic tests with adequate controls, we show here that recombinant plant CGI-58 has none of the proposed activities previously described. Recombinant plant and mouse CGI-58 both lack acyltransferase activity towards either lysophosphatidylglycerol or lysophosphatidic acid to form phosphatidylglycerol or phosphatidic acid and recombinant plant CGI-58 does not catalyze TAG or phospholipid hydrolysis. However, expression of recombinant plant CGI-58, but not mouse CGI-58, led to a decrease in phosphatidylglycerol in all strains of E. coli tested, and a mutation of the putative catalytic residues restored a wild-type phenotype. The potential activities of plant CGI-58 are subsequently discussed. PMID:26745266

  20. Reassessing the Potential Activities of Plant CGI-58 Protein.

    PubMed

    Khatib, Abdallah; Arhab, Yani; Bentebibel, Assia; Abousalham, Abdelkarim; Noiriel, Alexandre

    2016-01-01

    Comparative Gene Identification-58 (CGI-58) is a widespread protein found in animals and plants. This protein has been shown to participate in lipolysis in mice and humans by activating Adipose triglyceride lipase (ATGL), the initial enzyme responsible for the triacylglycerol (TAG) catabolism cascade. Human mutation of CGI-58 is the cause of Chanarin-Dorfman syndrome, an orphan disease characterized by a systemic accumulation of TAG which engenders tissue disorders. The CGI-58 protein has also been shown to participate in neutral lipid metabolism in plants and, in this case, a mutation again provokes TAG accumulation. Although its roles as an ATGL coactivator and in lipid metabolism are quite clear, the catalytic activity of CGI-58 is still in question. The acyltransferase activities of CGI-58 have been speculated about, reported or even dismissed and experimental evidence that CGI-58 expressed in E. coli possesses an unambiguous catalytic activity is still lacking. To address this problem, we developed a new set of plasmids and site-directed mutants to elucidate the in vivo effects of CGI-58 expression on lipid metabolism in E. coli. By analyzing the lipid composition in selected E. coli strains expressing CGI-58 proteins, and by reinvestigating enzymatic tests with adequate controls, we show here that recombinant plant CGI-58 has none of the proposed activities previously described. Recombinant plant and mouse CGI-58 both lack acyltransferase activity towards either lysophosphatidylglycerol or lysophosphatidic acid to form phosphatidylglycerol or phosphatidic acid and recombinant plant CGI-58 does not catalyze TAG or phospholipid hydrolysis. However, expression of recombinant plant CGI-58, but not mouse CGI-58, led to a decrease in phosphatidylglycerol in all strains of E. coli tested, and a mutation of the putative catalytic residues restored a wild-type phenotype. The potential activities of plant CGI-58 are subsequently discussed.

  1. Rat C-reactive protein activates the autologous complement system.

    PubMed

    Diaz Padilla, Niubel; Bleeker, Wim K; Lubbers, Yvonne; Rigter, Gemma M M; Van Mierlo, Gerard J; Daha, Mohamed R; Hack, C Erik

    2003-08-01

    Activation of complement is a biological function of human C-reactive protein (hCRP), whereas rat CRP (rCRP) has been claimed to be unable to activate complement. As important biological functions of proteins are probably conserved among species, we re-evaluated, using various ligands, the capability of rCRP to activate complement. The activation of complement by hCRP and rCRP was investigated in solid- and fluid-phase systems. In the solid-phase system, purified CRP was fixed to enzyme-linked immunosorbent assay (ELISA) plates and incubated with human or rat recalcified plasma. Dose-dependent binding of human and rat C3 and C4 was observed to human and rat CRP, respectively. In the fluid-phase system, recalcified rat plasma, which contains about 500 mg/l of CRP, or human plasma supplemented with hCRP, were incubated with lyso-phosphatidylcholine. A dose-dependent activation of complement was observed upon incubation with this ligand, as reflected by the generation of activated C4 as well as of CRP-complement complexes. This activation was, in both cases, inhibited by preincubation of plasma with p-aminophosphorylcholine, a specific inhibitor of the interaction of CRP with its ligands, or by chelation of calcium ions. We conclude that rat CRP, similarly to human CRP, can activate autologous complement. These results support the notion that opsonization of ligands with complement is an important biological function of CRP.

  2. Auxin efflux by PIN-FORMED proteins is activated by two different protein kinases, D6 PROTEIN KINASE and PINOID.

    PubMed

    Zourelidou, Melina; Absmanner, Birgit; Weller, Benjamin; Barbosa, Inês C R; Willige, Björn C; Fastner, Astrid; Streit, Verena; Port, Sarah A; Colcombet, Jean; de la Fuente van Bentem, Sergio; Hirt, Heribert; Kuster, Bernhard; Schulze, Waltraud X; Hammes, Ulrich Z; Schwechheimer, Claus

    2014-06-19

    The development and morphology of vascular plants is critically determined by synthesis and proper distribution of the phytohormone auxin. The directed cell-to-cell distribution of auxin is achieved through a system of auxin influx and efflux transporters. PIN-FORMED (PIN) proteins are proposed auxin efflux transporters, and auxin fluxes can seemingly be predicted based on the--in many cells--asymmetric plasma membrane distribution of PINs. Here, we show in a heterologous Xenopus oocyte system as well as in Arabidopsis thaliana inflorescence stems that PIN-mediated auxin transport is directly activated by D6 PROTEIN KINASE (D6PK) and PINOID (PID)/WAG kinases of the Arabidopsis AGCVIII kinase family. At the same time, we reveal that D6PKs and PID have differential phosphosite preferences. Our study suggests that PIN activation by protein kinases is a crucial component of auxin transport control that must be taken into account to understand auxin distribution within the plant.

  3. Pivotal Role of Mitogen-Activated Protein Kinase-Activated Protein Kinase 2 in Inflammatory Pulmonary Diseases

    PubMed Central

    Qian, Feng; Deng, Jing; Wang, Gang; Ye, Richard D.; Christman, John W.

    2016-01-01

    Mitogen-activated protein kinase (MAPK)-activated protein kinase (MK2) is exclusively regulated by p38 MAPK in vivo. Upon activation of p38 MAPK, MK2 binds with p38 MAPK, leading to phosphorylation of TTP, Hsp27, Akt and Cdc25 that are involved in regulation of various essential cellular functions. In this review, we discuss current knowledge about molecular mechanisms of MK2 in regulation of TNF-α production, NADPH oxidase activation, neutrophil migration, and DNA-damage-induced cell cycle arrest which are involved in the molecular pathogenesis of acute lung injury, pulmonary fibrosis, and non-small-cell lung cancer. Collectively current and emerging new information indicate that developing MK2 inhibitors and blocking MK2-mediated signal pathways is a potential therapeutic strategy for treatment of inflammatory and fibrotic lung diseases and lung cancer. PMID:26119506

  4. RNF4-Dependent Oncogene Activation by Protein Stabilization.

    PubMed

    Thomas, Jane J; Abed, Mona; Heuberger, Julian; Novak, Rostislav; Zohar, Yaniv; Beltran Lopez, Angela P; Trausch-Azar, Julie S; Ilagan, Ma Xenia G; Benhamou, David; Dittmar, Gunnar; Kopan, Raphael; Birchmeier, Walter; Schwartz, Alan L; Orian, Amir

    2016-09-20

    Ubiquitylation regulates signaling pathways critical for cancer development and, in many cases, targets proteins for degradation. Here, we report that ubiquitylation by RNF4 stabilizes otherwise short-lived oncogenic transcription factors, including β-catenin, Myc, c-Jun, and the Notch intracellular-domain (N-ICD) protein. RNF4 enhances the transcriptional activity of these factors, as well as Wnt- and Notch-dependent gene expression. While RNF4 is a SUMO-targeted ubiquitin ligase, protein stabilization requires the substrate's phosphorylation, rather than SUMOylation, and binding to RNF4's arginine-rich motif domain. Stabilization also involves generation of unusual polyubiquitin chains and docking of RNF4 to chromatin. Biologically, RNF4 enhances the tumor phenotype and is essential for cancer cell survival. High levels of RNF4 mRNA correlate with poor survival of a subgroup of breast cancer patients, and RNF4 protein levels are elevated in 30% of human colon adenocarcinomas. Thus, RNF4-dependent ubiquitylation translates transient phosphorylation signal(s) into long-term protein stabilization, resulting in enhanced oncoprotein activation. PMID:27653698

  5. A Novel Method for Assessing the Chaperone Activity of Proteins

    PubMed Central

    Hristozova, Nevena; Tompa, Peter; Kovacs, Denes

    2016-01-01

    Protein chaperones are molecular machines which function both during homeostasis and stress conditions in all living organisms. Depending on their specific function, molecular chaperones are involved in a plethora of cellular processes by playing key roles in nascent protein chain folding, transport and quality control. Among stress protein families–molecules expressed during adverse conditions, infection, and diseases–chaperones are highly abundant. Their molecular functions range from stabilizing stress-susceptible molecules and membranes to assisting the refolding of stress-damaged proteins, thereby acting as protective barriers against cellular damage. Here we propose a novel technique to test and measure the capability for protective activity of known and putative chaperones in a semi-high throughput manner on a plate reader. The current state of the art does not allow the in vitro measurements of chaperone activity in a highly parallel manner with high accuracy or high reproducibility, thus we believe that the method we report will be of significant benefit in this direction. The use of this method may lead to a considerable increase in the number of experimentally verified proteins with such functions, and may also allow the dissection of their molecular mechanism for a better understanding of their function. PMID:27564234

  6. Redox Control of Protein Arginine Methyltransferase 1 (PRMT1) Activity*

    PubMed Central

    Morales, Yalemi; Nitzel, Damon V.; Price, Owen M.; Gui, Shanying; Li, Jun; Qu, Jun; Hevel, Joan M.

    2015-01-01

    Elevated levels of asymmetric dimethylarginine (ADMA) correlate with risk factors for cardiovascular disease. ADMA is generated by the catabolism of proteins methylated on arginine residues by protein arginine methyltransferases (PRMTs) and is degraded by dimethylarginine dimethylaminohydrolase. Reports have shown that dimethylarginine dimethylaminohydrolase activity is down-regulated and PRMT1 protein expression is up-regulated under oxidative stress conditions, leading many to conclude that ADMA accumulation occurs via increased synthesis by PRMTs and decreased degradation. However, we now report that the methyltransferase activity of PRMT1, the major PRMT isoform in humans, is impaired under oxidative conditions. Oxidized PRMT1 displays decreased activity, which can be rescued by reduction. This oxidation event involves one or more cysteine residues that become oxidized to sulfenic acid (-SOH). We demonstrate a hydrogen peroxide concentration-dependent inhibition of PRMT1 activity that is readily reversed under physiological H2O2 concentrations. Our results challenge the unilateral view that increased PRMT1 expression necessarily results in increased ADMA synthesis and demonstrate that enzymatic activity can be regulated in a redox-sensitive manner. PMID:25911106

  7. Mitogen-activated protein kinase and abscisic acid signal transduction.

    PubMed

    Heimovaara-Dijkstra, S; Testerink, C; Wang, M

    2000-01-01

    The phytohormone abscisic acid (ABA) is a classical plant hormone, responsible for regulation of abscission, diverse aspects of plant and seed development, stress responses and germination. It was found that ABA signal transduction in plants can involve the activity of type 2C-phosphatases (PP2C), calcium, potassium, pH and a transient activation of MAP kinase. The ABA signal transduction cascades have been shown to be tissue-specific, the transient activation of MAP kinase has until now only been found in barley aleurone cells. However, type 2C phosphatases are involved in the induction of most ABA responses, as shown by the PP2C-deficient abi-mutants. These phosphatases show high homology with phosphatases that regulate MAP kinase activity in yeast. In addition, the role of farnesyl transferase as a negative regulator of ABA responses also indicates towards involvement of MAP kinase in ABA signal transduction. Farnesyl transferase is known to regulate Ras proteins, Ras proteins in turn are known to regulate MAP kinase activation. Interestingly, Ras-like proteins were detected in barley aleurone cells. Further establishment of the involvement of MAP kinase in ABA signal transduction and its role therein, still awaits more study.

  8. Protein kinase C controls activation of the DNA integrity checkpoint

    PubMed Central

    Soriano-Carot, María; Quilis, Inma; Bañó, M. Carmen; Igual, J. Carlos

    2014-01-01

    The protein kinase C (PKC) superfamily plays key regulatory roles in numerous cellular processes. Saccharomyces cerevisiae contains a single PKC, Pkc1, whose main function is cell wall integrity maintenance. In this work, we connect the Pkc1 protein to the maintenance of genome integrity in response to genotoxic stresses. Pkc1 and its kinase activity are necessary for the phosphorylation of checkpoint kinase Rad53, histone H2A and Xrs2 protein after deoxyribonucleic acid (DNA) damage, indicating that Pkc1 is required for activation of checkpoint kinases Mec1 and Tel1. Furthermore, Pkc1 electrophoretic mobility is delayed after inducing DNA damage, which reflects that Pkc1 is post-translationally modified. This modification is a phosphorylation event mediated by Tel1. The expression of different mammalian PKC isoforms at the endogenous level in yeast pkc1 mutant cells revealed that PKCδ is able to activate the DNA integrity checkpoint. Finally, downregulation of PKCδ activity in HeLa cells caused a defective activation of checkpoint kinase Chk2 when DNA damage was induced. Our results indicate that the control of the DNA integrity checkpoint by PKC is a mechanism conserved from yeast to humans. PMID:24792164

  9. Activation of autophagy by unfolded proteins during endoplasmic reticulum stress.

    PubMed

    Yang, Xiaochen; Srivastava, Renu; Howell, Stephen H; Bassham, Diane C

    2016-01-01

    Endoplasmic reticulum stress is defined as the accumulation of unfolded proteins in the endoplasmic reticulum, and is caused by conditions such as heat or agents that cause endoplasmic reticulum stress, including tunicamycin and dithiothreitol. Autophagy, a major pathway for degradation of macromolecules in the vacuole, is activated by these stress agents in a manner dependent on inositol-requiring enzyme 1b (IRE1b), and delivers endoplasmic reticulum fragments to the vacuole for degradation. In this study, we examined the mechanism for activation of autophagy during endoplasmic reticulum stress in Arabidopsis thaliana. The chemical chaperones sodium 4-phenylbutyrate and tauroursodeoxycholic acid were found to reduce tunicamycin- or dithiothreitol-induced autophagy, but not autophagy caused by unrelated stresses. Similarly, over-expression of BINDING IMMUNOGLOBULIN PROTEIN (BIP), encoding a heat shock protein 70 (HSP70) molecular chaperone, reduced autophagy. Autophagy activated by heat stress was also found to be partially dependent on IRE1b and to be inhibited by sodium 4-phenylbutyrate, suggesting that heat-induced autophagy is due to accumulation of unfolded proteins in the endoplasmic reticulum. Expression in Arabidopsis of the misfolded protein mimics zeolin or a mutated form of carboxypeptidase Y (CPY*) also induced autophagy in an IRE1b-dependent manner. Moreover, zeolin and CPY* partially co-localized with the autophagic body marker GFP-ATG8e, indicating delivery to the vacuole by autophagy. We conclude that accumulation of unfolded proteins in the endoplasmic reticulum is a trigger for autophagy under conditions that cause endoplasmic reticulum stress. PMID:26616142

  10. Current activities of the Yersinia effector protein YopM.

    PubMed

    Höfling, Sabrina; Grabowski, Benjamin; Norkowski, Stefanie; Schmidt, M Alexander; Rüter, Christian

    2015-05-01

    Yersinia outer protein M (YopM) belongs to the group of Yop effector proteins, which are highly conserved among pathogenic Yersinia species. During infection, the effectors are delivered into the host cell cytoplasm via the type 3 secretion system to subvert the host immune response and support the survival of Yersinia. In contrast to the other Yop effectors, YopM does not possess a known enzymatic activity and its molecular mechanism(s) of action remain(s) poorly understood. However, YopM was shown to promote colonization and dissemination of Yersinia, thus being crucial for the pathogen's virulence in vivo. Moreover, YopM interacts with several host cell proteins and might utilize them to execute its anti-inflammatory activities. The results obtained so far indicate that YopM is a multifunctional protein that counteracts the host immune defense by multiple activities, which are at least partially independent of each other. Finally, its functions seem to be also influenced by differences between the specific YopM isoforms expressed by Yersinia subspecies. In this review, we focus on the global as well as more specific contribution of YopM to virulence of Yersinia during infection and point out the various extra- and intracellular molecular functions of YopM. In addition, the novel cell-penetrating ability of recombinant YopM and its potential applications as a self-delivering immunomodulatory therapeutic will be discussed.

  11. Pharmacological activities in thermal proteins: relationships in molecular evolution

    NASA Technical Reports Server (NTRS)

    Fox, S. W.; Hefti, F.; Hartikka, J.; Junard, E.; Przybylski, A. T.; Vaughan, G.

    1987-01-01

    The model of protobiological events that has been presented in these pages has increasing relevance to pharmacological research. The thermal proteins that function as key substances in the proteinoid theory have recently been found to prolong the survival of rat forebrain neurons in culture and to stimulate the growth of neurites. A search for such activity in thermal proteins added to cultures of modern neurons was suggested by the fact that some of the microspheres assembled from proteinoids rich in hydrophobic amino acids themselves generate fibrous outgrowths.

  12. Pharmacological activities in thermal proteins: relationships in molecular evolution.

    PubMed

    Fox, S W; Hefti, F; Hartikka, J; Junard, E; Przybylski, A T; Vaughan, G

    1987-01-01

    The model of protobiological events that has been presented in these pages has increasing relevance to pharmacological research. The thermal proteins that function as key substances in the proteinoid theory have recently been found to prolong the survival of rat forebrain neurons in culture and to stimulate the growth of neurites. A search for such activity in thermal proteins added to cultures of modern neurons was suggested by the fact that some of the microspheres assembled from proteinoids rich in hydrophobic amino acids themselves generate fibrous outgrowths.

  13. Protein Kinase Cδ Mediates Neurogenic but Not Mitogenic Activation of Mitogen-Activated Protein Kinase in Neuronal Cells

    PubMed Central

    Corbit, Kevin C.; Foster, David A.; Rosner, Marsha Rich

    1999-01-01

    In several neuronal cell systems, fibroblast-derived growth factor (FGF) and nerve growth factor (NGF) act as neurogenic agents, whereas epidermal growth factor (EGF) acts as a mitogen. The mechanisms responsible for these different cellular fates are unclear. We report here that although FGF, NGF, and EGF all activate mitogen-activated protein (MAP) kinase (extracellular signal-related kinase [ERK]) in rat hippocampal (H19-7) and pheochromocytoma (PC12) cells, the activation of ERK by the neurogenic agents FGF and NGF is dependent upon protein kinase Cδ (PKCδ), whereas ERK activation in response to the mitogenic EGF is independent of PKCδ. Antisense PKCδ oligonucleotides or the PKCδ-specific inhibitor rottlerin inhibited FGF- and NGF-induced, but not EGF-induced, ERK activation. In contrast, EGF-induced ERK activation was inhibited by the phosphatidylinositol-3-kinase inhibitor wortmannin, which had no effect upon FGF-induced ERK activation. Rottlerin also inhibited the activation of MAP kinase kinase (MEK) in response to activated Raf, but had no effect upon c-Raf activity or ERK activation by activated MEK. These results indicate that PKCδ functions either downstream from or in parallel with c-Raf, but upstream of MEK. Inhibition of PKCδ also blocked neurite outgrowth induced by FGF and NGF in PC12 cells and by activated Raf in H19-7 cells, indicating a role for PKCδ in the neurogenic effects of FGF, NGF, and Raf. Interestingly, the PKCδ requirement is apparently cell type specific, since FGF-induced ERK activation was independent of PKCδ in NIH 3T3 murine fibroblasts, in which FGF is a mitogen. These data demonstrate that PKCδ contributes to growth factor specificity and response in neuronal cells and may also promote cell-type-specific differences in growth factor signaling. PMID:10330161

  14. Novel condensation products having high activity to insolubilize proteins and protein-insolubilized products

    SciTech Connect

    Krasnobajew, V.; Boeniger, R.

    1980-01-01

    According to the invention a substantially more active product with respect to the fixing or insolubilization pf proteins, including enzymes, is obtained when 1,3 phenylenediamine is condensed with glutardialdehyde. One application of the process is the enzymatic hydrolysis of lactose in milk products by lactase.

  15. Pharmacokinetics of activated protein C in guinea pigs

    SciTech Connect

    Berger, H. Jr.; Kirstein, C.G.; Orthner, C.L. )

    1991-05-15

    Protein C is a vitamin K-dependent zymogen of the serine protease, activated protein C (APC), an important regulatory enzyme in hemostasis. In view of the potential of human APC as an anticoagulant and profibrinolytic agent, the pharmacokinetics and tissue distribution of APC were studied in guinea pigs. The plasma elimination of a trace dose of {sup 125}I-APC was biphasic following an initial rapid elimination of approximately 15% of the injected dose within 1 to 2 minutes. This rapid removal of {sup 125}I-APC from the circulation was found to be a result of an association with the liver regardless of the route of injection. Essentially identical results were obtained with active site-blocked forms of APC generated with either diisopropylfluorophosphate or D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone, which indicates that the active site was not essential for the liver association. Accumulation of all three forms of APC in the liver peaked at 30 minutes and then declined as increasing amounts of degraded radiolabeled material appeared in the gastrointestinal tract and urine. Removal of the gamma-carboxyglutamic acid (gla) domain of diisopropylphosphoryl-APC resulted in a 50% reduction in the association with liver and an accumulation in the kidneys. Protein C and protein S were cleared from the circulation at rates approximately one-half and one-fourth, respectively, that of APC. Both in vitro and in vivo, APC was found to form complexes with protease inhibitors present in guinea pig plasma. Complex formation resulted in a more rapid disappearance of the enzymatic activity of APC than elimination of the protein moiety. These findings indicate two distinct mechanisms for the elimination of APC. One mechanism involves reaction with plasma protease inhibitors and subsequent elimination by specific hepatic receptors. (Abstract Truncated)

  16. Functions of AMP-activated protein kinase in adipose tissue

    PubMed Central

    Daval, Marie; Foufelle, Fabienne; Ferré, Pascal

    2006-01-01

    AMP-activated protein kinase (AMPK) is involved in cellular energy homeostasis. Its functions have been extensively studied in muscles and liver. AMPK stimulates pathways which increase energy production (glucose transport, fatty acid oxidation) and switches off pathways which consume energy (lipogenesis, protein synthesis, gluconeogenesis). This has led to the concept that AMPK has an interesting pharmaceutical potential in situations of insulin resistance and it is indeed the target of existing drugs and hormones which improve insulin sensitivity. Adipose tissue is a key player in energy metabolism through the release of substrates and hormones involved in metabolism and insulin sensitivity. Activation of AMPK in adipose tissue can be achieved through situations such as fasting and exercise. Leptin and adiponectin as well as hypoglycaemic drugs are activators of adipose tissue AMPK. This activation probably involves changes in the AMP/ATP ratio and the upstream kinase LKB1. When activated, AMPK limits fatty acid efflux from adipocytes and favours local fatty acid oxidation. Since fatty acids have a key role in insulin resistance, especially in muscles, activating AMPK in adipose tissue might be found to be beneficial in insulin-resistant states, particularly as AMPK activation also reduces cytokine secretion in adipocytes. PMID:16709632

  17. Activation of G Proteins by Guanine Nucleotide Exchange Factors Relies on GTPase Activity.

    PubMed

    Stanley, Rob J; Thomas, Geraint M H

    2016-01-01

    G proteins are an important family of signalling molecules controlled by guanine nucleotide exchange and GTPase activity in what is commonly called an 'activation/inactivation cycle'. The molecular mechanism by which guanine nucleotide exchange factors (GEFs) catalyse the activation of monomeric G proteins is well-established, however the complete reversibility of this mechanism is often overlooked. Here, we use a theoretical approach to prove that GEFs are unable to positively control G protein systems at steady-state in the absence of GTPase activity. Instead, positive regulation of G proteins must be seen as a product of the competition between guanine nucleotide exchange and GTPase activity--emphasising a central role for GTPase activity beyond merely signal termination. We conclude that a more accurate description of the regulation of G proteins via these processes is as a 'balance/imbalance' mechanism. This result has implications for the understanding of intracellular signalling processes, and for experimental strategies that rely on modulating G protein systems. PMID:26986850

  18. Regulation of taurine transporter activity in LLC-PK1 cells: role of protein synthesis and protein kinase C activation.

    PubMed

    Jones, D P; Miller, L A; Dowling, C; Chesney, R W

    1991-11-01

    Taurine transporter activity increases after exposure of cultured renal epithelial cells to taurine-free medium for 24 h and decreases after incubation in high (500 microM) taurine. This adaptive response mimics that observed in rat kidney after manipulation of dietary taurine. In order to elucidate potential mechanisms involved in the regulation of beta-amino acid transporter activity, the role of RNA transcription, protein synthesis, and protein import (trafficking), as well as protein kinase C activation, on the control of taurine transport was examined in the continuous proximally derived LLC-PK1 renal cell line. Inhibition of RNA transcription with actinomycin D did not alter the up-regulatory and down-regulatory adaptive responses. Inhibition of protein synthesis with cycloheximide prevented the increased taurine transport in response to taurine-free medium as well as the decrease in taurine transport after exposure to high taurine. Colchicine prevented the response to taurine-free medium but had no effect on the response to high-taurine medium. Exposure of confluent cell monolayers to the active phorbol esters, phorbol 12-myristate 13-acetate and phorbol 12,13 dibutyrate, resulted in a reduction in taurine uptake. The effect was seen within minutes of exposure but was not observed in the presence of the inactive phorbol 4-alpha. This inhibitory action was blocked by staurosporin, an inhibitor of protein kinase C (PKC). Treatment of cells with the diacylglycerol kinase inhibitor R59022, which results in increased intracellular diacylglycerol, a natural stimulant of PKC, also inhibited taurine uptake, providing further evidence for a specific effect of PKC activation.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Implications of a peroxisome proliferator-activated receptor alpha (PPARα) ligand clofibrate in breast cancer.

    PubMed

    Chandran, Karthic; Goswami, Sudeshna; Sharma-Walia, Neelam

    2016-03-29

    Inflammatory and invasive breast cancers are aggressive and require better understanding for the development of new treatments and more accurate prognosis. Here, we detected high expression of PPARα in human primary inflammatory (SUM149PT) and highly invasive (SUM1315MO2) breast cancer cells, and tissue sections of human breast cancer. PPARα ligands are clinically used to treat dyslipidemia. Among lipid lowering drugs clofibrate, fenofibrate and WY14643, clofibrate showed high chemo-sensitivity towards breast cancer cells. Clofibrate treatment significantly induced PPARα DNA binding activity, and remarkably reduced cyclooxygenase-2/PGE2 and 5-lipoxygenase/LTB4 inflammatory pathways. Clofibrate treatment reduced the proliferation of breast cancer cells probably by inhibiting NF-κB and ERK1/2 activation, reducing cyclinD1, cyclinA, cyclinE, and inducing pro-apoptotic P21 levels. Surprisingly, the expression of lipogenic pathway genes including SREBP-1c (sterol regulatory element-binding protein-1c), HMG-CoA synthase, SPTLC1 (serine palmitoyltransferase long-chain), and Acyl-CoA oxidase (ACO) decreased with a concurrent increase in fatty acid oxidation genes such as CPT-1a (carnitine palmitoyltransferase 1a) and SREBP-2 (Sterol regulatory element-binding protein-2). Clofibrate treatment induced secretion of free fatty acids and effectively decreased the level of phosphorylated active form of fatty acid synthase (FASN), an enzyme catalyzing de novo synthesis of fatty acids. High level of coactivators steroid receptor coactivator-1 (SRC-1) and histone acetylase CBP-300 (CREB binding protein-300) were observed in the nuclear complexes of clofibrate treated breast cancer cells. These findings implicate that stimulating PPARα by safe, well-tolerated, and clinically approved clofibrate may provide a safer and more effective strategy to target the signaling, lipogenic, and inflammatory pathways in aggressive forms of breast cancer. PMID:26621841

  20. Implications of a peroxisome proliferator-activated receptor alpha (PPARα) ligand clofibrate in breast cancer

    PubMed Central

    Goswami, Sudeshna

    2016-01-01

    Inflammatory and invasive breast cancers are aggressive and require better understanding for the development of new treatments and more accurate prognosis. Here, we detected high expression of PPARα in human primary inflammatory (SUM149PT) and highly invasive (SUM1315MO2) breast cancer cells, and tissue sections of human breast cancer. PPARα ligands are clinically used to treat dyslipidemia. Among lipid lowering drugs clofibrate, fenofibrate and WY14643, clofibrate showed high chemo-sensitivity towards breast cancer cells. Clofibrate treatment significantly induced PPARα DNA binding activity, and remarkably reduced cyclooxygenase-2/PGE2 and 5-lipoxygenase/LTB4 inflammatory pathways. Clofibrate treatment reduced the proliferation of breast cancer cells probably by inhibiting NF-κB and ERK1/2 activation, reducing cyclinD1, cyclinA, cyclinE, and inducing pro-apoptotic P21 levels. Surprisingly, the expression of lipogenic pathway genes including SREBP-1c (sterol regulatory element-binding protein-1c), HMG-CoA synthase, SPTLC1 (serine palmitoyltransferase long-chain), and Acyl-CoA oxidase (ACO) decreased with a concurrent increase in fatty acid oxidation genes such as CPT-1a (carnitine palmitoyltransferase 1a) and SREBP-2 (Sterol regulatory element-binding protein-2). Clofibrate treatment induced secretion of free fatty acids and effectively decreased the level of phosphorylated active form of fatty acid synthase (FASN), an enzyme catalyzing de novo synthesis of fatty acids. High level of coactivators steroid receptor coactivator-1 (SRC-1) and histone acetylase CBP-300 (CREB binding protein-300) were observed in the nuclear complexes of clofibrate treated breast cancer cells. These findings implicate that stimulating PPARα by safe, well-tolerated, and clinically approved clofibrate may provide a safer and more effective strategy to target the signaling, lipogenic, and inflammatory pathways in aggressive forms of breast cancer. PMID:26621841

  1. L-Alanylglutamine inhibits signaling proteins that activate protein degradation, but does not affect proteins that activate protein synthesis after an acute resistance exercise.

    PubMed

    Wang, Wanyi; Choi, Ran Hee; Solares, Geoffrey J; Tseng, Hung-Min; Ding, Zhenping; Kim, Kyoungrae; Ivy, John L

    2015-07-01

    Sustamine™ (SUS) is a dipeptide composed of alanine and glutamine (AlaGln). Glutamine has been suggested to increase muscle protein accretion; however, the underlying molecular mechanisms of glutamine on muscle protein metabolism following resistance exercise have not been fully addressed. In the present study, 2-month-old rats climbed a ladder 10 times with a weight equal to 75 % of their body mass attached at the tail. Rats were then orally administered one of four solutions: placebo (PLA-glycine = 0.52 g/kg), whey protein (WP = 0.4 g/kg), low dose of SUS (LSUS = 0.1 g/kg), or high dose of SUS (HSUS = 0.5 g/kg). An additional group of sedentary (SED) rats was intubated with glycine (0.52 g/kg) at the same time as the ladder-climbing rats. Blood samples were collected immediately after exercise and at either 20 or 40 min after recovery. The flexor hallucis longus (FHL), a muscle used for climbing, was excised at 20 or 40 min post exercise and analyzed for proteins regulating protein synthesis and degradation. All supplements elevated the phosphorylation of FOXO3A above SED at 20 min post exercise, but only the SUS supplements significantly reduced the phosphorylation of AMPK and NF-kB p65. SUS supplements had no effect on mTOR signaling, but WP supplementation yielded a greater phosphorylation of mTOR, p70S6k, and rpS6 compared with PLA at 20 min post exercise. However, by 40 min post exercise, phosphorylation of mTOR and rpS6 in PLA had risen to levels not different than WP. These results suggest that SUS blocks the activation of intracellular signals for MPB, whereas WP accelerates mRNA translation. PMID:25837301

  2. Antioxidant and antifungal activity of different extracts obtained from aerial parts of Inula crithmoides L.

    PubMed

    Bucchini, Anahi; Ricci, Donata; Messina, Federica; Marcotullio, Maria Carla; Curini, Massimo; Giamperi, Laura

    2015-01-01

    The total phenolic content, antioxidant and antifungal activities of three Inula crithmoides extracts (n-hexane, methylene chloride and MeOH) were investigated. The methanolic extract showed the highest total phenolic content. In the DPPH assay, the methanolic and hexane extracts exhibited the highest DPPH-radical scavenging activity; in the 5-lipoxygenase assay, the hexane extract showed greater inhibitory effect with an IC50 similar to that of Trolox and ascorbic acid. The antifungal activity of the methanolic extract revealed a higher activity against Phytophtora cryptogea and Alternaria solani. PMID:25426874

  3. Methods of measuring Protein Disulfide Isomerase activity: a critical overview

    NASA Astrophysics Data System (ADS)

    Watanabe, Monica; Laurindo, Francisco; Fernandes, Denise

    2014-09-01

    Protein disulfide isomerase is an essential redox chaperone from the endoplasmic reticulum (ER) and is responsible for correct disulfide bond formation in nascent proteins. PDI is also found in other cellular locations in the cell, particularly the cell surface. Overall, PDI contributes to ER and global cell redox homeostasis and signaling. The knowledge about PDI structure and function progressed substantially based on in vitro studies using recombinant PDI and chimeric proteins. In these experimental scenarios, PDI reductase and chaperone activities are readily approachable. In contrast, assays to measure PDI isomerase activity, the hallmark of PDI family, are more complex. Assessment of PDI roles in cells and tissues mainly relies on gain- or loss-of-function studies. However, there is limited information regarding correlation of experimental readouts with the distinct types of PDI activities. In this mini-review, we evaluate the main methods described for measuring the different kinds of PDI activity: thiol reductase, thiol oxidase, thiol isomerase and chaperone. We emphasize the need to use appropriate controls and the role of critical interferents (e.g., detergent, presence of reducing agents). We also discuss the translation of results from in vitro studies with purified recombinant PDI to cellular and tissue samples, with critical comments on the interpretation of results.

  4. Analysis of antifreeze protein activity using colorimetric gold nanosensors

    NASA Astrophysics Data System (ADS)

    Jing, Xu; Choi, Ho-seok; Park, Ji-In; Kim, Young-Pil

    2015-07-01

    High activity and long stability of antifreeze proteins (AFPs), also known as ice-binding proteins (IBPs), are necessary for exerting their physiological functions in biotechnology and cryomedicine. Here we report a simple analysis of antifreeze protein activity and stability based on self-assembly of gold nanoparticles (AuNPs) via freezing and thawing cycles. While the mercaptosuccinic acid-capped AuNP (MSA-AuNP) was easily self-assembled after a freezing/thawing cycle, due to the mechanical attack of ice crystal on the MSA-AuNP surface, the presence of AFP impeded the self-assembly of MSA-AuNP via the interaction of AFP with ice crystals via freezing and thawing cycles, which led to a strong color in the MSA-AuNP solution. As a result, the aggregation parameter (E520/E650) of MSA-AuNP showed the rapid detection of both activity and stability of AFPs. We suggest that our newly developed method is very suitable for measuring antifreeze activity and stability in a simple and rapid manner with reliable quantification.

  5. Antibacterial activity of a lectin-like Burkholderia cenocepacia protein.

    PubMed

    Ghequire, Maarten G K; De Canck, Evelien; Wattiau, Pierre; Van Winge, Iris; Loris, Remy; Coenye, Tom; De Mot, René

    2013-08-01

    Bacteriocins of the LlpA family have previously been characterized in the γ-proteobacteria Pseudomonas and Xanthomonas. These proteins are composed of two MMBL (monocot mannose-binding lectin) domains, a module predominantly and abundantly found in lectins from monocot plants. Genes encoding four different types of LlpA-like proteins were identified in genomes from strains belonging to the Burkholderia cepacia complex (Bcc) and the Burkholderia pseudomallei group. A selected recombinant LlpA-like protein from the human isolate Burkholderia cenocepacia AU1054 displayed narrow-spectrum genus-specific antibacterial activity, thus representing the first functionally characterized bacteriocin within this β-proteobacterial genus. Strain-specific killing was confined to other members of the Bcc, with mostly Burkholderia ambifaria strains being susceptible. In addition to killing planktonic cells, this bacteriocin also acted as an antibiofilm agent.

  6. Efficient expression and purification of biologically active human cystatin proteins.

    PubMed

    Chauhan, Sakshi; Tomar, Raghuvir S

    2016-02-01

    Cystatins are reversible cysteine protease inhibitor proteins. They are known to play important roles in controlling cathepsins, neurodegenerative disease, and in immune system regulation. Production of recombinant cystatin proteins is important for biochemical and function characterization. In this study, we cloned and expressed human stefin A, stefin B and cystatin C in Escherichia coli. Human stefin A, stefin B and cystatin C were purified from soluble fraction. For cystatin C, we used various chaperone plasmids to make cystatin C soluble, as it is reported to localize in inclusion bodies. Trigger factor, GroES-GroEL, DnaK-DnaJ-GrpE chaperones lead to the presence of cystatin C in the soluble fraction. Immobilized metal affinity chromatography, glutathione sepharose and anion exchange chromatography techniques were employed for efficient purification of these proteins. Their biological activities were tested by inhibition assays against cathepsin L and H3 protease.

  7. Antibacterial activity of a lectin-like Burkholderia cenocepacia protein.

    PubMed

    Ghequire, Maarten G K; De Canck, Evelien; Wattiau, Pierre; Van Winge, Iris; Loris, Remy; Coenye, Tom; De Mot, René

    2013-08-01

    Bacteriocins of the LlpA family have previously been characterized in the γ-proteobacteria Pseudomonas and Xanthomonas. These proteins are composed of two MMBL (monocot mannose-binding lectin) domains, a module predominantly and abundantly found in lectins from monocot plants. Genes encoding four different types of LlpA-like proteins were identified in genomes from strains belonging to the Burkholderia cepacia complex (Bcc) and the Burkholderia pseudomallei group. A selected recombinant LlpA-like protein from the human isolate Burkholderia cenocepacia AU1054 displayed narrow-spectrum genus-specific antibacterial activity, thus representing the first functionally characterized bacteriocin within this β-proteobacterial genus. Strain-specific killing was confined to other members of the Bcc, with mostly Burkholderia ambifaria strains being susceptible. In addition to killing planktonic cells, this bacteriocin also acted as an antibiofilm agent. PMID:23737242

  8. Novel mechanisms for activated protein C cytoprotective activities involving noncanonical activation of protease-activated receptor 3.

    PubMed

    Burnier, Laurent; Mosnier, Laurent O

    2013-08-01

    The direct cytoprotective activities of activated protein C (APC) on cells convey therapeutic, relevant, beneficial effects in injury and disease models in vivo and require the endothelial protein C receptor (EPCR) and protease activated receptor 1 (PAR1). Thrombin also activates PAR1, but its effects on cells contrast APC's cytoprotective effects. To gain insights into mechanisms for these contrasting cellular effects, protease activated receptor 3 (PAR3) activation by APC and thrombin was studied. APC cleaved PAR3 on transfected and endothelial cells in the presence of EPCR. Remarkably, APC cleaved a synthetic PAR3 N-terminal peptide at Arg41, whereas thrombin cleaved at Lys38. On cells, APC failed to cleave R41Q-PAR3, whereas K38Q-PAR3 was still cleaved by APC but not by thrombin. PAR3 tethered-ligand peptides beginning at amino acid 42, but not those beginning at amino acid 39, conveyed endothelial barrier-protective effects. In vivo, the APC-derived PAR3 tethered-ligand peptide, but not the thrombin-derived PAR3 peptide, blunted vascular endothelial growth factor (VEGF)-induced vascular permeability. These data indicate that PAR3 cleavage by APC at Arg41 can initiate distinctive APC-like cytoprotective effects. These novel insights help explain the differentiation of APC's cytoprotective versus thrombin's proinflammatory effects on cells and suggest a unique contributory role for PAR3 in the complex mechanisms underlying APC cytoprotective effects. PMID:23788139

  9. Protein-tyrosine phosphatase activity of CD45 is activated by sequential phosphorylation by two kinases.

    PubMed Central

    Stover, D R; Walsh, K A

    1994-01-01

    We describe a potential regulatory mechanism for the transmembrane protein-tyrosine phosphatase CD45. Phosphorylation on both tyrosine and serine residues in vitro results in an activation of CD45 specifically toward one artificial substrate but not another. The activation of these kinases appears to be order dependent, as it is enhanced when phosphorylation of tyrosine precedes that of serine but phosphorylation in the reverse order yields no activation. Any of four protein-tyrosine kinases tested, in combination with the protein-serine/threonine kinase, casein kinase II, was capable of mediating this activation in vitro. The time course of phosphorylation of CD45 in response to T-cell activation is consistent with the possibility that this regulatory mechanism is utilized in vivo. Images PMID:7518565

  10. Interleukin 2 activates extracellular signal-regulated protein kinase 2

    PubMed Central

    1993-01-01

    Interleukin 2 (IL-2) stimulated activation of the 42-kD extracellular signal-regulated kinase 2 (Erk2) in murine IL-3-dependent cells, expressing either high or intermediate affinity IL-2 receptors. Activation was both rapid, occurring within 5 min of IL-2 addition, and prolonged, remaining elevated for 30 min. Activation of Erk2 appeared to be necessary for IL-2 stimulation of proliferation, as deletion of a region of the cytoplasmic domain of the IL-2 receptor beta chain, essential for IL-2 stimulation of proliferation, abolished Erk2 activation by IL-2. Furthermore, cells that had been deprived of cytokine for 24 h were then refractory to IL-2 stimulation of both Erk2 activity and proliferation. However, elevation of Erk2 activity was not sufficient to stimulate proliferation, as protein kinase C activation stimulated Erk2 activity but not DNA synthesis. Also, cells exposed to IL-2 in the presence of rapamycin showed full Erk2 activation but not DNA synthesis. These data suggest that IL-2 must stimulate both Erk2 activity and a further pathway(s) to trigger cell proliferation. PMID:8376945

  11. Novel Biosensor of Membrane Protein Proximity Based on Fluorogen Activated Proteins.

    PubMed

    Vasilev, Kalin V; Gallo, Eugenio; Shank, Nathaniel; Jarvik, Jonathan W

    2016-01-01

    We describe a novel biosensor system for reporting proximity between cell surface proteins in live cultured cells. The biosensor takes advantage of recently developed fluorogen-activating proteins (FAPs) that display fluorescence only when bound to otherwise-nonfluorescent fluorogen molecules. To demonstrate feasibility for the approach, two recombinant rapamycin-binding proteins were expressed as single-pass plasma membrane proteins in HeLa cells; one of the proteins (scAvd- FRB) carried an extracellular avidin tag; the other (HL1-TO1-FKBP) carried an extracellular FAP. Cells were incubated with a membrane-impermeable bivalent ligand (biotin-PEG2000-DIR) consisting of biotin joined to a dimethyl-indole red (DIR) fluorogen by a polyethylene glycol linker, thus tethering the fluorogen to the scAvd-FRB fusion protein. Addition of rapamycin, which promotes FKBP-FRB dimerization and thereby brings the FAP in close proximity to the tethered fluorogen, led to a significant increase in DIR fluorescence. We call the new proximity assay TEFLA, for tethered fluorogen assay. PMID:27055753

  12. Strategies for the recovery of active proteins through refolding of bacterial inclusion body proteins

    PubMed Central

    Vallejo, Luis Felipe; Rinas, Ursula

    2004-01-01

    Recent advances in generating active proteins through refolding of bacterial inclusion body proteins are summarized in conjunction with a short overview on inclusion body isolation and solubilization procedures. In particular, the pros and cons of well-established robust refolding techniques such as direct dilution as well as less common ones such as diafiltration or chromatographic processes including size exclusion chromatography, matrix- or affinity-based techniques and hydrophobic interaction chromatography are discussed. Moreover, the effect of physical variables (temperature and pressure) as well as the presence of buffer additives on the refolding process is elucidated. In particular, the impact of protein stabilizing or destabilizing low- and high-molecular weight additives as well as micellar and liposomal systems on protein refolding is illustrated. Also, techniques mimicking the principles encountered during in vivo folding such as processes based on natural and artificial chaperones and propeptide-assisted protein refolding are presented. Moreover, the special requirements for the generation of disulfide bonded proteins and the specific problems and solutions, which arise during process integration are discussed. Finally, the different strategies are examined regarding their applicability for large-scale production processes or high-throughput screening procedures. PMID:15345063

  13. Genipin Suppresses NLRP3 Inflammasome Activation Through Uncoupling Protein-2

    PubMed Central

    Rajanbabu, Venugopal; Galam, Lakshmi; Fukumoto, Jutaro; Enciso, Juan; Tadikonda, Pratima; Lane, Troy N.; Bandyopadhyay, Sayantani; Parthasarathy, Prasanna Tamarapu; Cho, Young; Cho, Seong Ho; Lee, Yong Chul; Lockey, Richard F.; Kolliputi, Narasaiah

    2015-01-01

    Incomplete clearance of apoptotic cells and reactive oxygen species (ROS) release are known to trigger inflammasome activation causing severe inflammation in acute lung injury and various metabolic and autoimmune diseases. Moreover, it has been reported that apoptotic cell clearance and ROS-mediated apoptosis critically depend on mitochondrial uncoupling protein-2 (UCP2). However, the relationship between UCP2 and inflammasome activation has not been studied. This report investigates the role of UCP2 in the expression and activation of NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome in human macrophages. We found that UCP2 overexpression significantly enhanced the expression levels of NLRP3. The NLRP3 expression levels were significantly suppressed in THP1 cells treated with genipin, a UCP2 inhibitor, compared to controls. In addition, genipin altered adenosine triphosphate (ATP)- and hydrogen peroxide (H2O2)-mediated interleukin-1 beta (IL-1β) secretion and significantly suppressed caspase-1 activity in inflammasome-activated human macrophages. Taken together, our results suggest that genipin modulates NLRP3 inflammasome activation and ATP- or H2O2-mediated IL-1β release. PMID:26123077

  14. Membrane lipids regulate ganglioside GM2 catabolism and GM2 activator protein activity[S

    PubMed Central

    Anheuser, Susi; Breiden, Bernadette; Schwarzmann, Günter; Sandhoff, Konrad

    2015-01-01

    Ganglioside GM2 is the major lysosomal storage compound of Tay-Sachs disease. It also accumulates in Niemann-Pick disease types A and B with primary storage of SM and with cholesterol in type C. Reconstitution of GM2 catabolism with β-hexosaminidase A and GM2 activator protein (GM2AP) at uncharged liposomal surfaces carrying GM2 as substrate generated only a physiologically irrelevant catabolic rate, even at pH 4.2. However, incorporation of anionic phospholipids into the GM2 carrying liposomes stimulated GM2 hydrolysis more than 10-fold, while the incorporation of plasma membrane stabilizing lipids (SM and cholesterol) generated a strong inhibition of GM2 hydrolysis, even in the presence of anionic phospholipids. Mobilization of membrane lipids by GM2AP was also inhibited in the presence of cholesterol or SM, as revealed by surface plasmon resonance studies. These lipids also reduced the interliposomal transfer rate of 2-NBD-GM1 by GM2AP, as observed in assays using Förster resonance energy transfer. Our data raise major concerns about the usage of recombinant His-tagged GM2AP compared with untagged protein. The former binds more strongly to anionic GM2-carrying liposomal surfaces, increases GM2 hydrolysis, and accelerates intermembrane transfer of 2-NBD-GM1, but does not mobilize membrane lipids. PMID:26175473

  15. Localization microscopy using noncovalent fluorogen activation by genetically encoded fluorogen activating proteins

    PubMed Central

    Maji, Suvrajit; Huang, Fang; Szent-Gyorgyi, Chris; Lidke, Diane S.; Lidke, Keith A.; Bruchez, Marcel P.

    2014-01-01

    The noncovalent equilibrium activation of a fluorogenic malachite green dye and its cognate fluorogen activating protein has been exploited to produce a sparse labeling distribution of densely tagged genetically encoded proteins, enabling single molecule detection and superresolution imaging in fixed and living cells. These sparse labeling conditions are achieved by control of the dye concentration in the milieu, and do not require any photoswitching or photoactivation. The labeling is achieved using physiological buffers and cellular media, and does not require additives or switching buffer to obtain superresolution images. We evaluate superresolution properties and images obtained from a selected fluorogen activating protein clone fused to actin, and show that the photon counts per object fall between those typically reported for fluorescent proteins and switching dye-pairs, resulting in 10-30 nm localization precision per object. This labeling strategy complements existing approaches, and may simplify multicolor labeling of cellular structures. PMID:24194371

  16. Mitogen-activated protein kinase cascades in Vitis vinifera

    PubMed Central

    Çakır, Birsen; Kılıçkaya, Ozan

    2015-01-01

    Protein phosphorylation is one of the most important mechanisms to control cellular functions in response to external and endogenous signals. Mitogen-activated protein kinases (MAPK) are universal signaling molecules in eukaryotes that mediate the intracellular transmission of extracellular signals resulting in the induction of appropriate cellular responses. MAPK cascades are composed of four protein kinase modules: MAPKKK kinases (MAPKKKKs), MAPKK kinases (MAPKKKs), MAPK kinases (MAPKKs), and MAPKs. In plants, MAPKs are activated in response to abiotic stresses, wounding, and hormones, and during plant pathogen interactions and cell division. In this report, we performed a complete inventory of MAPK cascades genes in Vitis vinifera, the whole genome of which has been sequenced. By comparison with MAPK, MAPK kinases, MAPK kinase kinases and MAPK kinase kinase kinase kinase members of Arabidopsis thaliana, we revealed the existence of 14 MAPKs, 5 MAPKKs, 62 MAPKKKs, and 7 MAPKKKKs in Vitis vinifera. We identified orthologs of V. vinifera putative MAPKs in different species, and ESTs corresponding to members of MAPK cascades in various tissues. This work represents the first complete inventory of MAPK cascades in V. vinifera and could help elucidate the biological and physiological functions of these proteins in V. vinifera. PMID:26257761

  17. Interaction of receptor-activity-modifying protein1 with tubulin.

    PubMed

    Kunz, Thomas H; Mueller-Steiner, Sarah; Schwerdtfeger, Kerstin; Kleinert, Peter; Troxler, Heinz; Kelm, Jens M; Ittner, Lars M; Fischer, Jan A; Born, Walter

    2007-08-01

    Receptor-activity-modifying protein (RAMP) 1 is an accessory protein of the G protein-coupled calcitonin receptor-like receptor (CLR). The CLR/RAMP1 heterodimer defines a receptor for the potent vasodilatory calcitonin gene-related peptide. A wider tissue distribution of RAMP1, as compared to that of the CLR, is consistent with additional biological functions. Here, glutathione S-transferase (GST) pull-down, coimmunoprecipitation and yeast two-hybrid experiments identified beta-tubulin as a novel RAMP1-interacting protein. GST pull-down experiments indicated interactions between the N- and C-terminal domains of RAMP1 and beta-tubulin. Yeast two-hybrid experiments confirmed the interaction between the N-terminal region of RAMP1 and beta-tubulin. Interestingly, alpha-tubulin was co-extracted with beta-tubulin in pull-down experiments and immunoprecipitation of RAMP1 coprecipitated alpha- and beta-tubulin. Confocal microscopy indicated colocalization of RAMP1 and tubulin predominantly in axon-like processes of neuronal differentiated human SH-SY5Y neuroblastoma cells. In conclusion, the findings point to biological roles of RAMP1 beyond its established interaction with G protein-coupled receptors. PMID:17493758

  18. Antibacterial activity of a lectin-like Burkholderia cenocepacia protein

    PubMed Central

    Ghequire, Maarten G K; Canck, Evelien; Wattiau, Pierre; Winge, Iris; Loris, Remy; Coenye, Tom; Mot, René

    2013-01-01

    Abstract Bacteriocins of the LlpA family have previously been characterized in the γ-proteobacteria Pseudomonas and Xanthomonas. These proteins are composed of two MMBL (monocot mannose-binding lectin) domains, a module predominantly and abundantly found in lectins from monocot plants. Genes encoding four different types of LlpA-like proteins were identified in genomes from strains belonging to the Burkholderia cepacia complex (Bcc) and the Burkholderia pseudomallei group. A selected recombinant LlpA-like protein from the human isolate Burkholderia cenocepacia AU1054 displayed narrow-spectrum genus-specific antibacterial activity, thus representing the first functionally characterized bacteriocin within this β-proteobacterial genus. Strain-specific killing was confined to other members of the Bcc, with mostly Burkholderia ambifaria strains being susceptible. In addition to killing planktonic cells, this bacteriocin also acted as an antibiofilm agent. Bacteriocins mediate highly selective antagonism among closely related bacteria but such antimicrobial proteins have not yet been reported in Burkholderia. We identified a lectin-like protein of the LlpA family in a Burkholderia cenocepacia human isolate that strain-specifically and selectively kills planktonic and biofilm cells of other Burkholderia cepacia complex members. PMID:23737242

  19. Protective activity of salidroside against ethanol-induced gastric ulcer via the MAPK/NF-κB pathway in vivo and in vitro.

    PubMed

    Chang, Xiayun; Luo, Fen; Jiang, Wenjiao; Zhu, Lingpeng; Gao, Jin; He, He; Wei, Tingting; Gong, Shilin; Yan, Tianhua

    2015-09-01

    Salidroside (Sal) is a traditional Chinese medicine with various pharmacological effects. The present study aimed to investigate the protective effect of Sal on ethanol-induced acute gastric ulcer and H2O2-induced gastric epithelial cell damage. 0.2 ml ethanol and 400 μM H2O2 were applied to establish a gastric ulcer model in vivo and in vitro respectively. The production of interleukin (IL)-6, interleukin (IL)-1β and tumor necrosis factor (TNF)-α was analyzed, as well as myeloperoxidase (MPO), malondialdehyde (MDA) and superoxide dismutase (SOD). MTT assay was used to detect cell viability. In addition, MAPK/NF-κB signal pathway-related proteins p-ERK, p-JNK, p-p38, p-IκBα and p-NF-κBp65 were analyzed to determine the underlying protective mechanism. Downstream genes such as cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX) and leukotrienes B4 (LTB4) were also measured. Obtained data indicated that Sal inhibited the overproduction of pro-inflammatory cytokines and enhanced antioxidant activity. Collectively, it is assumed that Sal could alleviate ethanol-induced acute gastric ulcer and H2O2-induced gastric epithelial cell damage through the MAPK/NF-κB pathway.

  20. Detection of expansin proteins and activity during tomato fruit ontogeny.

    PubMed

    Rose, J K; Cosgrove, D J; Albersheim, P; Darvill, A G; Bennett, A B

    2000-08-01

    Expansins are plant proteins that have the capacity to induce extension in isolated cell walls and are thought to mediate pH-dependent cell expansion. J.K.C. Rose, H.H. Lee, and A.B. Bennett ([1997] Proc Natl Acad Sci USA 94: 5955-5960) reported the identification of an expansin gene (LeExp1) that is specifically expressed in ripening tomato (Lycopersicon esculentum) fruit where cell wall disassembly, but not cell expansion, is prominent. Expansin expression during fruit ontogeny was examined using antibodies raised to recombinant LeExp1 or a cell elongation-related expansin from cucumber (CsExp1). The LeExp1 antiserum detected expansins in extracts from ripe, but not preripe tomato fruit, in agreement with the pattern of LeExp1 mRNA accumulation. In contrast, antibodies to CsExp1 cross-reacted with expansins in early fruit development and the onset of ripening, but not at a later ripening stage. These data suggest that ripening-related and expansion-related expansin proteins have distinct antigenic epitopes despite overall high sequence identity. Expansin proteins were detected in a range of fruit species and showed considerable variation in abundance; however, appreciable levels of expansin were not present in fruit of the rin or Nr tomato mutants that exhibit delayed and reduced softening. LeExp1 protein accumulation was ethylene-regulated and matched the previously described expression of mRNA, suggesting that expression is not regulated at the level of translation. We report the first detection of expansin activity in several stages of fruit development and while characteristic creep activity was detected in young and developing tomato fruit and in ripe pear, avocado, and pepper, creep activity in ripe tomato showed qualitative differences, suggesting both hydrolytic and expansin activities.

  1. C-reactive protein activates complement in infarcted human myocardium.

    PubMed

    Nijmeijer, Remco; Lagrand, Wim K; Lubbers, Yvonne T P; Visser, Cees A; Meijer, Chris J L M; Niessen, Hans W M; Hack, C Erik

    2003-07-01

    Circulating levels of C-reactive protein (CRP) constitute a cardiovascular risk marker. Immunohistochemical studies have revealed co-localization of CRP and activated complement in human infarcted myocardium suggesting CRP to enhance inflammation in ischemic myocardium by inducing local complement activation. The aim was to establish whether CRP activates complement in infarcted human myocardium and to assess the relationship between this activation and the duration of infarction. Myocardial tissue samples from 56 patients that had died from acute myocardial infarction were evaluated. Specimens were taken from infarcted as well as noninfarcted sites of the heart. CRP-mediated complement activation was assessed by immunohistochemistry and by measuring levels of complement, CRP, and CRP-complement complexes, specific markers for CRP-mediated activation, in homogenates of the heart. Infarctions of 12 hours to 5 days had significantly more extensive depositions of complement and CRP and contained significantly more CRP, activated complement, and CRP-complement complexes than infarctions that were less than 12 hours old. Levels of CRP complexes correlated significantly with CRP and complement concentrations in the infarctions, as well as with the extent of complement and CRP depositions as measured via immunohistochemistry. Specific activation products of CRP-mediated activation of complement are increased in infarcts of more than 12 hours in duration and correlate with the extent of complement depositions. Hence, CRP seems to enhance local inflammatory reactions ensuing in human myocardial infarcts of more than 12 hours duration.

  2. Negative regulation of lymphocyte activation by the adaptor protein LAX.

    PubMed

    Zhu, Minghua; Granillo, Olivia; Wen, Renren; Yang, Kaiyong; Dai, Xuezhi; Wang, Demin; Zhang, Weiguo

    2005-05-01

    The membrane-associated adaptor protein LAX is a linker for activation of T cells (LAT)-like molecule that is expressed in lymphoid tissues. Upon stimulation of T or B cells, it is phosphorylated and interacts with Grb2 and the p85 subunit of PI3K. LAX, however, is not capable of replacing LAT in the TCR signaling pathway. In this study we report that upon T or B cell activation, the LAX protein was up-regulated dramatically. Although disruption of the LAX gene by homologous recombination had no major impact on lymphocyte development, it caused a significant reduction in CD23 expression on mature B cells. Interestingly, naive LAX(-/-) mice had spontaneous germinal center formation. Compared with normal T and B cells, LAX(-/-) T and B cells were hyperresponsive and had enhanced calcium flux, protein tyrosine phosphorylation, MAPK and Akt activation, and cell survival upon engagement of the T or B AgRs. Our data demonstrate that LAX functions as a negative regulator in lymphocyte signaling.

  3. T cell-activating protein on murine lymphocytes.

    PubMed

    Yeh, E T; Reiser, H; Benacerraf, B; Rock, K L

    1986-12-01

    A functional T cell surface molecule, T cell-activating protein (TAP), has been identified on murine lymphocytes. TAP is a protein with an apparent molecular mass of 10-12 kilodaltons (kDa) nonreduced, 16-17 kDa reduced. Cross-linking of TAP can result in profound activation of T lymphocytes to produce lymphokines and to enter the cell cycle. Furthermore, antibody binding to TAP can modulate antigen-driven T cell stimulation. Current data suggest that TAP is physically distinct from the T cell receptor complex. On unstimulated lymphocytes, TAP is expressed on T cells and defines heterogeneity within the major T cell subsets. Its profile of expression is rapidly altered on cell activation. Ontologically, it is first detected in the thymus, where it is found on both the most immature and the most mature cell subsets, and it is functional on both. Together, these TAP+ cells constitute a small fraction of thymocytes. TAP expression, however, defines the immunocompetent compartment of the thymus, and thus could be involved in functional maturation. Finally, the gene controlling TAP expression has been mapped, and is tightly linked to a locus of hematopoietic antigens (Ly-6). TAP is molecularly distinct from these antigens. Furthermore, all of these proteins show a markedly distinct developmental regulation in their cell surface expression.

  4. Protein inhibitor of activated STAT3 inhibits adipogenic gene expression

    SciTech Connect

    Deng Jianbei; Hua Kunjie; Caveney, Erica J.; Takahashi, Nobuyuki; Harp, Joyce B. . E-mail: jharp@unc.edu

    2006-01-20

    Protein inhibitor of activated STAT3 (PIAS3), a cytokine-induced repressor of signal transducer and activator of transcription 3 (STAT3) and a modulator of a broad array of nuclear proteins, is expressed in white adipose tissue, but its role in adipogenesis is not known. Here, we determined that PIAS3 was constitutively expressed in 3T3-L1 cells at all stages of adipogenesis. However, it translocated from the nucleus to the cytoplasm 4 days after induction of differentiation by isobutylmethylxanthine, dexamethasone, and insulin (MDI). In ob/ob mice, PIAS3 expression was increased in white adipose tissue depots compared to lean mice and was found in the cytoplasm of adipocytes. Overexpression of PIAS3 in differentiating preadipocytes, which localized primarily to the nucleus, inhibited mRNA level gene expression of adipogenic transcription factors C/EBP{alpha} and PPAR{gamma}, as well as their downstream target genes aP2 and adiponectin. PIAS3 also inhibited C/EBP{alpha} promoter activation mediated specifically by insulin, but not dexamethasone or isobutylmethylxanthine. Taken together, these data suggest that PIAS3 may play an inhibitory role in adipogenesis by modulating insulin-activated transcriptional activation events. Increased PIAS3 expression in adipose tissue may play a role in the metabolic disturbances of obesity.

  5. AMP-activated Protein Kinase Is Activated as a Consequence of Lipolysis in the Adipocyte

    Technology Transfer Automated Retrieval System (TEKTRAN)

    AMP-activated protein kinase (AMPK) is activated in adipocytes during exercise and other states in which lipolysis is stimulated. However, the mechanism(s) responsible for this effect and its physiological relevance are unclear. To examine these questions, 3T3-L1 adipocytes were treated with agents...

  6. Pokeweed Antiviral Protein, a Ribosome Inactivating Protein: Activity, Inhibition and Prospects

    PubMed Central

    Domashevskiy, Artem V.; Goss, Dixie J.

    2015-01-01

    Viruses employ an array of elaborate strategies to overcome plant defense mechanisms and must adapt to the requirements of the host translational systems. Pokeweed antiviral protein (PAP) from Phytolacca americana is a ribosome inactivating protein (RIP) and is an RNA N-glycosidase that removes specific purine residues from the sarcin/ricin (S/R) loop of large rRNA, arresting protein synthesis at the translocation step. PAP is thought to play an important role in the plant’s defense mechanism against foreign pathogens. This review focuses on the structure, function, and the relationship of PAP to other RIPs, discusses molecular aspects of PAP antiviral activity, the novel inhibition of this plant toxin by a virus counteraction—a peptide linked to the viral genome (VPg), and possible applications of RIP-conjugated immunotoxins in cancer therapeutics. PMID:25635465

  7. Pokeweed antiviral protein, a ribosome inactivating protein: activity, inhibition and prospects.

    PubMed

    Domashevskiy, Artem V; Goss, Dixie J

    2015-01-28

    Viruses employ an array of elaborate strategies to overcome plant defense mechanisms and must adapt to the requirements of the host translational systems. Pokeweed antiviral protein (PAP) from Phytolacca americana is a ribosome inactivating protein (RIP) and is an RNA N-glycosidase that removes specific purine residues from the sarcin/ricin (S/R) loop of large rRNA, arresting protein synthesis at the translocation step. PAP is thought to play an important role in the plant's defense mechanism against foreign pathogens. This review focuses on the structure, function, and the relationship of PAP to other RIPs, discusses molecular aspects of PAP antiviral activity, the novel inhibition of this plant toxin by a virus counteraction-a peptide linked to the viral genome (VPg), and possible applications of RIP-conjugated immunotoxins in cancer therapeutics.

  8. Crystal Structure of the Protein Kinase Domain of Yeast AMP-Activated Protein Kinase Snf1

    SciTech Connect

    Rudolph,M.; Amodeo, G.; Bai, Y.; Tong, L.

    2005-01-01

    AMP-activated protein kinase (AMPK) is a master metabolic regulator, and is an important target for drug development against diabetes, obesity, and other diseases. AMPK is a hetero-trimeric enzyme, with a catalytic ({alpha}) subunit, and two regulatory ({beta} and {gamma}) subunits. Here we report the crystal structure at 2.2 Angstrom resolution of the protein kinase domain (KD) of the catalytic subunit of yeast AMPK (commonly known as SNF1). The Snf1-KD structure shares strong similarity to other protein kinases, with a small N-terminal lobe and a large C-terminal lobe. Two negative surface patches in the structure may be important for the recognition of the substrates of this kinase.

  9. [Virucidal activity of disinfectants. Influence of the serum protein upon the virucidal activity of disinfectants].

    PubMed

    Noda, M; Matsuda, S; Kobayashi, M

    2000-08-01

    Five disinfectants were tested for virucidal activity on three DNA viruses and three RNA viruses in the presence or absence of serum protein. Disinfectants of the aldehyde and halogen groups had a virucidal activity on human herpes virus, bovine rhabdo virus, human immunodeficiency virus, human adeno virus, porcine parvo virus, and polio virus. Disinfectants of the invert and amphoteric soap groups, and biganide group had a destructive effect on RNA and DNA viruses possessing an envelope. The presence of serum protein exerted great influence upon the virucidal activity of disinfectants of the invert and amphoteric soap groups. PMID:11019515

  10. Modulation of haem oxygenase-1 expression by nitric oxide and leukotrienes in zymosan-activated macrophages

    PubMed Central

    Vicente, Ana María; Guillén, María Isabel; Alcaraz, María José

    2001-01-01

    Phagocytosis of unopsonized zymosan by RAW 264.7 macrophages upregulated protein expression of haem oxygenase-1 (HO-1), inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2) in a time- and concentration-dependent manner. In the presence of zymosan, exogenous prostaglandin E2 (PGE2) did not exert significant effects on the expression of these three enzymes. In contrast, exogenous leukotriene B4 (LTB4) and LTC4 in the nanomolar range inhibited HO-1 and iNOS expression, as well as nitrite accumulation. The COX inhibitors indomethacin and NS398 weakly inhibited HO-1 expression but had no effect on iNOS and COX-2 expression or nitrite. In contrast, the 5-lipoxygenase (5-LO) inhibitor ZM 230,487 significantly decreased HO-1, iNOS and nitrite, which were not affected by zileuton. Dexamethasone showed an inhibitory effect on HO-1 expression induced by zymosan. ZM 230,487 but not zileuton, inhibited the shift due to nuclear factor-κB (NF-κB), whereas they did not modify activator protein-1 (AP-1) binding. Our results suggest that inhibition of NF-κB binding could mediate the effects of ZM 230,487 on the modulation of HO-1 and iNOS protein expression. NOS inhibition by L-NG-nitroarginine methyl ester (L-NAME) or 1400 W abolished nitrite production and strongly reduced HO-1 expression. These results show an induction of HO-1 protein expression by zymosan phagocytosis in macrophages, with a positive modulatory role for endogenous NO and a negative regulation by exogenous LTs, likely dependent on the reduction of iNOS expression and NO production. PMID:11454666

  11. Granulocyte colony-stimulating factor administration to HIV-infected subjects augments reduced leukotriene synthesis and anticryptococcal activity in neutrophils.

    PubMed Central

    Coffey, M J; Phare, S M; George, S; Peters-Golden, M; Kazanjian, P H

    1998-01-01

    Neutrophil (PMN) dysfunction occurs in HIV infection. Leukotrienes (LT) are mediators derived from the 5-lipoxygenase (5-LO) pathway that play a role in host defense and are synthesized by PMN. We investigated the synthesis of LT by PMN from HIV-infected subjects. There was a reduction (4.0+/-1.3% of control) in LT synthesis in PMN from HIV-infected compared with normal subjects. This was associated with reduced expression of 5-LO-activating protein (31.2+/-9.6% of normal), but not of 5-LO itself. Since HIV does not directly infect PMN, we considered that these effects were due to reduced release of cytokines, such as granulocyte colony-stimulating factor (G-CSF). We examined the effect of G-CSF treatment (300 microgram daily for 5 d) on eight HIV-infected subjects. PMN were studied in vitro before therapy (day 1) and on days 4 and 7. LTB4 synthesis was increased on day 4 of G-CSF treatment, and returned toward day 1 levels on day 7. 5-LO and 5-LO-activating protein expression were increased in parallel. As a functional correlate to this increase in PMN LT synthesis by G-CSF, we examined the effects on killing of Cryptococcus neoformans. Anticryptococcal activity of PMN from HIV-infected subjects was less than that of PMN from normal subjects. G-CSF treatment improved fungistatic activity of PMN. This increase in antifungal activity was attenuated by in vitro treatment with the LT synthesis inhibitor, MK-886. In conclusion, PMN from HIV-infected subjects demonstrate reduced 5-LO metabolism and antifungal activity in vitro, which was reversed by in vivo G-CSF therapy. PMID:9710433

  12. Synthesis and biological activity of arylspiroborate salts derived from caffeic Acid phenethyl ester.

    PubMed

    Hébert, Martin J G; Flewelling, Andrew J; Clark, Trevor N; Levesque, Natalie A; Jean-François, Jacques; Surette, Marc E; Gray, Christopher A; Vogels, Christopher M; Touaibia, Mohamed; Westcott, Stephen A

    2015-01-01

    Two novel boron compounds containing caffeic acid phenethyl ester (CAPE) derivatives have been prepared and characterized fully. These new compounds and CAPE have been investigated for potential antioxidant and antimicrobial properties and their ability to inhibit 5-lipoxygenase and whether chelation to boron improves their biological activity. Sodium salt 4 was generally more active than ammonium salt 5 in the biological assays and surpassed the radical scavenging ability of CAPE. Compounds 4 and 5 were more active than CAPE and Zileuton in human polymorphonuclear leukocytes. These results clearly show the effectiveness of the synthesized salts as transporter of CAPE. PMID:25834744

  13. Synthesis and Biological Activity of Arylspiroborate Salts Derived from Caffeic Acid Phenethyl Ester

    PubMed Central

    Hébert, Martin J. G.; Flewelling, Andrew J.; Clark, Trevor N.; Jean-François, Jacques; Surette, Marc E.; Gray, Christopher A.; Vogels, Christopher M.; Touaibia, Mohamed; Westcott, Stephen A.

    2015-01-01

    Two novel boron compounds containing caffeic acid phenethyl ester (CAPE) derivatives have been prepared and characterized fully. These new compounds and CAPE have been investigated for potential antioxidant and antimicrobial properties and their ability to inhibit 5-lipoxygenase and whether chelation to boron improves their biological activity. Sodium salt 4 was generally more active than ammonium salt 5 in the biological assays and surpassed the radical scavenging ability of CAPE. Compounds 4 and 5 were more active than CAPE and Zileuton in human polymorphonuclear leukocytes. These results clearly show the effectiveness of the synthesized salts as transporter of CAPE. PMID:25834744

  14. Rapamycin induces mitogen-activated protein (MAP) kinase phosphatase-1 (MKP-1) expression through activation of protein kinase B and mitogen-activated protein kinase kinase pathways.

    PubMed

    Rastogi, Ruchi; Jiang, Zhongliang; Ahmad, Nisar; Rosati, Rita; Liu, Yusen; Beuret, Laurent; Monks, Robert; Charron, Jean; Birnbaum, Morris J; Samavati, Lobelia

    2013-11-22

    Mitogen-activated protein kinase phosphatase-1 (MKP-1), also known as dual specificity phosphatase-1 (DUSP-1), plays a crucial role in the deactivation of MAPKs. Several drugs with immune-suppressive properties modulate MKP-1 expression as part of their mechanism of action. We investigated the effect of mTOR inhibition through rapamycin and a dual mTOR inhibitor (AZD2014) on MKP-1 expression. Low dose rapamycin led to a rapid activation of both AKT and ERK pathways with a subsequent increase in MKP-1 expression. Rapamycin treatment led to phosphorylation of CREB, transcription factor 1 (ATF1), and ATF2, three transcription factors that bind to the cyclic AMP-responsive elements on the Mkp-1 promoter. Inhibition of either the MEK/ERK or the AKT pathway attenuated rapamycin-mediated MKP-1 induction. AZD2014 did not activate AKT but activated the ERK pathway, leading to a moderate MKP-1 induction. Using bone marrow-derived macrophages (BMDMs) derived from wild-type (WT) mice or mice deficient in AKT1 and AKT2 isoforms or BMDM from targeted deficiency in MEK1 and MEK2, we show that rapamycin treatment led to an increased MKP1 expression in BMDM from WT but failed to do so in BMDMs lacking the AKT1 isoform or MEK1 and MEK2. Importantly, rapamycin pretreatment inhibited LPS-mediated p38 activation and decreased nitric oxide and IL-6 production. Our work provides a conceptual framework for the observed immune modulatory effect of mTOR inhibition.

  15. Fast calcium sensor proteins for monitoring neural activity

    PubMed Central

    Badura, Aleksandra; Sun, Xiaonan Richard; Giovannucci, Andrea; Lynch, Laura A.; Wang, Samuel S.-H.

    2014-01-01

    Abstract. A major goal of the BRAIN Initiative is the development of technologies to monitor neuronal network activity during active information processing. Toward this goal, genetically encoded calcium indicator proteins have become widely used for reporting activity in preparations ranging from invertebrates to awake mammals. However, slow response times, the narrow sensitivity range of Ca2+ and in some cases, poor signal-to-noise ratio still limit their usefulness. Here, we review recent improvements in the field of neural activity-sensitive probe design with a focus on the GCaMP family of calcium indicator proteins. In this context, we present our newly developed Fast-GCaMPs, which have up to 4-fold accelerated off-responses compared with the next-fastest GCaMP, GCaMP6f. Fast-GCaMPs were designed by destabilizing the association of the hydrophobic pocket of calcium-bound calmodulin with the RS20 binding domain, an intramolecular interaction that protects the green fluorescent protein chromophore. Fast-GCaMP6f-RS06 and Fast-GCaMP6f-RS09 have rapid off-responses in stopped-flow fluorimetry, in neocortical brain slices, and in the intact cerebellum in vivo. Fast-GCaMP6f variants should be useful for tracking action potentials closely spaced in time, and for following neural activity in fast-changing compartments, such as axons and dendrites. Finally, we discuss strategies that may allow tracking of a wider range of neuronal firing rates and improve spike detection. PMID:25558464

  16. Positive feedback of protein kinase C proteolytic activation during apoptosis.

    PubMed Central

    Leverrier, Sabrina; Vallentin, Alice; Joubert, Dominique

    2002-01-01

    In contrast with protein kinase Calpha (PKCalpha) and PKCepsilon, which are better known for promoting cell survival, PKCdelta is known for its pro-apoptotic function, which is exerted mainly through a caspase-3-dependent proteolytic activation pathway. In the present study, we used the rat GH3B6 pituitary adenoma cell line to show that PKCalpha and PKCepsilon are activated and relocalized together with PKCdelta when apoptosis is induced by a genotoxic stress. Proteolytic activation is a crucial step used by the three isoforms since: (1) the catalytic domains of the PKCalpha, PKCepsilon or PKCdelta isoforms (CDalpha, CDepsilon and CDdelta respectively) accumulated, and this accumulation was dependent on the activity of both calpain and caspase; and (2) transient expression of CDalpha, CDepsilon or CDdelta sufficed to induce apoptosis. However, following this initial step of proteolytic activation, the pathways diverge; cytochrome c release and caspase-3 activation are induced by CDepsilon and CDdelta, but not by CDalpha. Another interesting finding of the present study is the proteolysis of PKCdelta induced by CDepsilon expression that revealed the existence of a cross-talk between PKC isoforms during apoptosis. Hence the PKC family may participate in the apoptotic process of pituitary adenoma cells at two levels: downstream of caspase and calpain, and via retro-activation of caspase-3, resulting in the amplification of its own proteolytic activation. PMID:12238950

  17. Circulating FGF21 proteolytic processing mediated by fibroblast activation protein

    PubMed Central

    Zhen, Eugene Y.; Jin, Zhaoyan; Ackermann, Bradley L.; Thomas, Melissa K.; Gutierrez, Jesus A.

    2015-01-01

    Fibroblast growth factor 21 (FGF21), a hormone implicated in the regulation of glucose homoeostasis, insulin sensitivity, lipid metabolism and body weight, is considered to be a promising therapeutic target for the treatment of metabolic disorders. Despite observations that FGF21 is rapidly proteolysed in circulation rending it potentially inactive, little is known regarding mechanisms by which FGF21 protein levels are regulated. We systematically investigated human FGF21 protein processing using mass spectrometry. In agreement with previous reports, circulating human FGF21 was found to be cleaved primarily after three proline residues at positions 2, 4 and 171. The extent of FGF21 processing was quantified in a small cohort of healthy human volunteers. Relative abundance of FGF21 proteins cleaved after Pro-2, Pro-4 and Pro-171 ranged from 16 to 30%, 10 to 25% and 10 to 34%, respectively. Dipeptidyl peptidase IV (DPP-IV) was found to be the primary protease responsible for N-terminal cleavages after residues Pro-2 and Pro-4. Importantly, fibroblast activation protein (FAP) was implicated as the protease responsible for C-terminal cleavage after Pro-171, rendering the protein inactive. The requirement of FAP for FGF21 proteolysis at the C-terminus was independently demonstrated by in vitro digestion, immunodepletion of FAP in human plasma, administration of an FAP-specific inhibitor and by human FGF21 protein processing patterns in FAP knockout mouse plasma. The discovery that FAP is responsible for FGF21 inactivation extends the FGF21 signalling pathway and may enable novel approaches to augment FGF21 actions for therapeutic applications. PMID:26635356

  18. Activation of G protein by opioid receptors: role of receptor number and G-protein concentration.

    PubMed

    Remmers, A E; Clark, M J; Alt, A; Medzihradsky, F; Woods, J H; Traynor, J R

    2000-05-19

    The collision-coupling model for receptor-G-protein interaction predicts that the rate of G-protein activation is dependent on receptor density, but not G-protein levels. C6 cells expressing mu- or delta-opioid receptors, or SH-SY5Y cells, were treated with beta-funaltrexamine (mu) or naltrindole-5'-isothiocyanate (delta) to decrease receptor number. The time course of full or partial agonist-stimulated ¿35SGTPgammaS binding did not vary in C6 cell membranes containing <1-25 pmol/mg mu-opioid receptor, or 1. 4-4.3 pmol/mg delta-opioid receptor, or in SHSY5Y cells containing 0. 16-0.39 pmol/mg receptor. The association of ¿35SGTPgammaS binding was faster in membranes from C6mu cells than from C6delta cells. A 10-fold reduction in functional G-protein, following pertussis toxin treatment, lowered the maximal level of ¿35SGTPgammaS binding but not the association rate. These data indicate a compartmentalization of opioid receptors and G protein at the cell membrane. PMID:10822058

  19. Protein kinase C directly phosphorylates the insulin receptor in vitro and reduces its protein-tyrosine kinase activity.

    PubMed Central

    Bollag, G E; Roth, R A; Beaudoin, J; Mochly-Rosen, D; Koshland, D E

    1986-01-01

    The beta subunit of purified insulin receptor is phosphorylated on a serine residue by purified preparations of protein kinase C (ATP: protein phosphotransferase, EC 2.7.1.37). This phosphorylation is inhibited by antibodies to protein kinase C and stimulated by phospholipids, diacylglycerol, and Ca2+. The phosphorylation of the receptor by protein kinase C does not affect its insulin-binding activity but does inhibit by 65% the receptor's intrinsic tyrosine-specific protein kinase activity (ATP: protein-tyrosine O-phosphotransferase, EC 2.7.1.112). These results indicate that activators of protein kinase C, such as phorbol esters, desensitize cells to insulin by direct protein kinase C action on the insulin receptor. Images PMID:3526339

  20. Activated G Protein Gαs Samples Multiple Endomembrane Compartments.

    PubMed

    Martin, Brent R; Lambert, Nevin A

    2016-09-23

    Heterotrimeric G proteins are localized to the plasma membrane where they transduce extracellular signals to intracellular effectors. G proteins also act at intracellular locations, and can translocate between cellular compartments. For example, Gαs can leave the plasma membrane and move to the cell interior after activation. However, the mechanism of Gαs translocation and its intracellular destination are not known. Here we use bioluminescence resonance energy transfer (BRET) to show that after activation, Gαs rapidly associates with the endoplasmic reticulum, mitochondria, and endosomes, consistent with indiscriminate sampling of intracellular membranes from the cytosol rather than transport via a specific vesicular pathway. The primary source of Gαs for endosomal compartments is constitutive endocytosis rather than activity-dependent internalization. Recycling of Gαs to the plasma membrane is complete 25 min after stimulation is discontinued. We also show that an acylation-deacylation cycle is important for the steady-state localization of Gαs at the plasma membrane, but our results do not support a role for deacylation in activity-dependent Gαs internalization. PMID:27528603

  1. Activity of lactoperoxidase when adsorbed on protein layers.

    PubMed

    Haberska, Karolina; Svensson, Olof; Shleev, Sergey; Lindh, Liselott; Arnebrant, Thomas; Ruzgas, Tautgirdas

    2008-09-15

    Lactoperoxidase (LPO) is an enzyme, which is used as an antimicrobial agent in a number of applications, e.g., food technology. In the majority of applications LPO is added to a homogeneous product phase or immobilised on product surface. In the latter case, however, the measurements of LPO activity are seldom reported. In this paper we have assessed LPO enzymatic activity on bare and protein modified gold surfaces by means of electrochemistry. It was found that LPO rapidly adsorbs to bare gold surfaces resulting in an amount of LPO adsorbed of 2.9mg/m(2). A lower amount of adsorbed LPO is obtained if the gold surface is exposed to bovine serum albumin, bovine or human mucin prior to LPO adsorption. The enzymatic activity of the adsorbed enzyme is in general preserved at the experimental conditions and varies only moderately when comparing bare gold and gold surface pretreated with the selected proteins. The measurement of LPO specific activity, however, indicate that it is about 1.5 times higher if LPO is adsorbed on gold surfaces containing a small amount of preadsorbed mucin in comparison to the LPO directly adsorbed on bare gold.

  2. Superoxide dismutase activity of Cu-bound prion protein

    NASA Astrophysics Data System (ADS)

    Hodak, Miroslav; Lu, Wenchang; Bernholc, Jerry

    2009-03-01

    Misfolding of the prion protein, PrP, has been linked to a group of neurodegenerative diseases, including the mad cow disease in cattle and the Creutzfeldt-Jakob disease in humans. The normal function of PrP is still unknown, but it was found that the PrP can efficiently bind Cu(II) ions. Early experiments suggested that Cu-PrP complex possesses significant superoxide dismutase (SOD) activity, but later experiments failed to confirm it and at present this issue remains unresolved. Using a recently developed hybrid DFT/DFT method, which combines Kohn-Sham DFT for the solute and its first solvation shells with orbital-free DFT for the remainder of the solvent, we have investigated SOD activity of PrP. The PrP is capable of incorporating Cu(II) ions in several binding modes and our calculations find that each mode has a different SOD activity. The highest activity found is comparable to those of well-known SOD proteins, suggesting that the conflicting experimental results may be due to different bindings of Cu(II) in those experiments.

  3. [National evaluation of the diagnosis of activated protein C resistance].

    PubMed

    Montiel-Manzano, Guadalupe; de la Peña-Díaz, Aurora; Majluf-Cruz, Abraham; Cesarman-Maus, Gabriela; Corona-de la Peña, Norma; Cruz-Cruz, Donají; Gaminio, Elizabeth; Martínez-Murillo, Carlos; Mayagoitia, Teresa; Miranda-Peralta, Enrique; Poblete, Teresita; Quintana-Martínez, Sandra; Ramírez, Raúl; Razo, Daniel; Ruiz de Chávez-Ochoa, Adriana; Reyes-Núñez, Virginia Adriana; Salazar, Rosario; Vicencio-Santiago, Guadalupe Virginia; Villa, Rosario; Reyes-Núñez, Aurelia Virginia

    2003-01-01

    Thrombophilia or prothrombotic state appears when activation of blood hemostatic mechanisms overcomes the physiological anticoagulant capacity allowing a thrombotic event. Thrombosis is the leading worldwide mortality cause and due to its high associated morbidity and mortality, it should be insisted in the opportune identification of a thrombophilic state. The study of thrombophilia identifies individuals at high risk for thrombosis. This meeting was conceived first to analyze the current status of the diagnosis of thrombophilia in Mexico and second to create the base for a national consensus for thrombophilia screening and for the establishment of a national center for laboratory reference and quality control for thrombophilia. Since searching of activated protein C resistance (APCR) and FV Leiden seem to have priority either in the clinical setting and in public health services, it was decided to start with these two abnormalities as a model to analyze the current status of thrombophilia diagnosis in the clinical laboratory. At this time, several thrombophilic abnormalities have been described however, APCR remains the most important cause of thrombophilia, accounting for as much as 20% to 60% of all venous thrombosis. APCR is a consequence of the resistance of activated FV to be inactivated by activated protein C. Procoagulant activity of activated FV increases the risk of thrombosis. Hereditary APCR is almost always due to a point mutation at the nucleotide 1691 of the FV gen inducing an Arg506Glu substitution in FV molecule. This mutation is better known as FV Leiden. Heterocygous carriers of FV Leiden have a thrombotic risk 5 to 10 times higher than general population while the risk for the homocygote state is increased 50 to 100-fold. When activated PC is added to plasma from patients with FV Leiden, this last resists the anticoagulant effect of activated PC. Therefore, thrombin production is not inhibited. This phenomenon is called APCR. The functional

  4. Schistosoma mansoni secretes a chemokine binding protein with antiinflammatory activity.

    PubMed

    Smith, Philip; Fallon, Rosie E; Mangan, Niamh E; Walsh, Caitriona M; Saraiva, Margarida; Sayers, Jon R; McKenzie, Andrew N J; Alcami, Antonio; Fallon, Padraic G

    2005-11-21

    The coevolution of humans and infectious agents has exerted selective pressure on the immune system to control potentially lethal infections. Correspondingly, pathogens have evolved with various strategies to modulate and circumvent the host's innate and adaptive immune response. Schistosoma species are helminth parasites with genes that have been selected to modulate the host to tolerate chronic worm infections, often for decades, without overt morbidity. The modulation of immunity by schistosomes has been shown to prevent a range of immune-mediated diseases, including allergies and autoimmunity. Individual immune-modulating schistosome molecules have, therefore, therapeutic potential as selective manipulators of the immune system to prevent unrelated diseases. Here we show that S. mansoni eggs secrete a protein into host tissues that binds certain chemokines and inhibits their interaction with host chemokine receptors and their biological activity. The purified recombinant S. mansoni chemokine binding protein (smCKBP) suppressed inflammation in several disease models. smCKBP is unrelated to host proteins and is the first described chemokine binding protein encoded by a pathogenic human parasite and may have potential as an antiinflammatory agent.

  5. Analysis of protein phosphorylation in nerve terminal reveals extensive changes in active zone proteins upon exocytosis

    PubMed Central

    Kohansal-Nodehi, Mahdokht; Chua, John JE; Urlaub, Henning; Jahn, Reinhard; Czernik, Dominika

    2016-01-01

    Neurotransmitter release is mediated by the fast, calcium-triggered fusion of synaptic vesicles with the presynaptic plasma membrane, followed by endocytosis and recycling of the membrane of synaptic vesicles. While many of the proteins governing these processes are known, their regulation is only beginning to be understood. Here we have applied quantitative phosphoproteomics to identify changes in phosphorylation status of presynaptic proteins in resting and stimulated nerve terminals isolated from the brains of Wistar rats. Using rigorous quantification, we identified 252 phosphosites that are either up- or downregulated upon triggering calcium-dependent exocytosis. Particularly pronounced were regulated changes of phosphosites within protein constituents of the presynaptic active zone, including bassoon, piccolo, and RIM1. Additionally, we have mapped kinases and phosphatases that are activated upon stimulation. Overall, our study provides a snapshot of phosphorylation changes associated with presynaptic activity and provides a foundation for further functional analysis of key phosphosites involved in presynaptic plasticity. DOI: http://dx.doi.org/10.7554/eLife.14530.001 PMID:27115346

  6. Hepatitis B virus x protein induces autophagy via activating death-associated protein kinase.

    PubMed

    Zhang, H-T; Chen, G G; Hu, B-G; Zhang, Z-Y; Yun, J-P; He, M-L; Lai, P B S

    2014-01-01

    Hepatitis B virus x protein (HBX), a product of hepatitis B virus (HBV), is a multifunctional protein that regulates viral replication and various cellular functions. Recently, HBX has been shown to induce autophagy; however, the responsible mechanism is not fully known. In this study, we established stable HBX-expressing epithelial Chang cells as the platform to study how HBX induced autophagy. The results showed that the overexpression of HBX resulted in starvation-induced autophagy. HBX-induced autophagy was related to its ability to dephosphorylate/activate death-associated protein kinase (DAPK). The block of DAPK by its siRNA significantly counteracted HBX-mediated autophagy, confirming the positive role of DAPK in this process. HBX also induced Beclin 1, which functions at the downstream of the DAPK-mediated autophagy pathway. Although HBX could activate JNK, a kinase known to participate in autophagy in certain conditions, the change in JNK failed to influence HBX-induced autophagy. In conclusion, HBX induces autophagy via activating DAPK in a pathway related to Beclin 1, but not JNK. This new finding should help us to understand the role of autophagy in HBX-mediated pathogenesis and thus may provide targets for intervening HBX-related disorders.

  7. TALE factors poise promoters for activation by Hox proteins.

    PubMed

    Choe, Seong-Kyu; Ladam, Franck; Sagerström, Charles G

    2014-01-27

    Hox proteins form complexes with TALE cofactors from the Pbx and Prep/Meis families to control transcription, but it remains unclear how Hox:TALE complexes function. Examining a Hoxb1b:TALE complex that regulates zebrafish hoxb1a transcription, we find maternally deposited TALE proteins at the hoxb1a promoter already during blastula stages. These TALE factors recruit histone-modifying enzymes to promote an active chromatin profile at the hoxb1a promoter and also recruit RNA polymerase II (RNAPII) and P-TEFb. However, in the presence of TALE factors, RNAPII remains phosphorylated on serine 5 and hoxb1a transcription is inefficient. By gastrula stages, Hoxb1b binds together with TALE factors to the hoxb1a promoter. This triggers P-TEFb-mediated transitioning of RNAPII to the serine 2-phosphorylated form and efficient hoxb1a transcription. We conclude that TALE factors access promoters during early embryogenesis to poise them for activation but that Hox proteins are required to trigger efficient transcription.

  8. Abscisic Acid Induces Mitogen-Activated Protein Kinase Activation in Barley Aleurone Protoplasts.

    PubMed

    Knetsch, MLW.; Wang, M.; Snaar-Jagalska, B. E.; Heimovaara-Dijkstra, S.

    1996-06-01

    Abscisic acid (ABA) induces a rapid and transient mitogen-activated protein (MAP) kinase activation in barley aleurone protoplasts. MAP kinase activity, measured as myelin basic protein phosphorylation by MAP kinase immunoprecipitates, increased after 1 min, peaked after 3 min, and decreased to basal levels after ~5 min of ABA treatment in vivo. Antibodies recognizing phosphorylated tyrosine residues precipitate with myelin basic protein kinase activity that has identical ABA activation characteristics and demonstrate that tyrosine phosphorylation of MAP kinase occurs during activation. The half-maximal concentration of ABA required for MAP kinase activation, 3 x 10-7 M, is very similar to that required for ABA-induced rab16 gene expression. The tyrosine phosphatase inhibitor phenylarsine oxide can completely block ABA-induced MAP kinase activation and rab16 gene expression. These results lead us to conclude that ABA activates MAP kinase via a tyrosine phosphatase and that these steps are a prerequisite for ABA induction of rab16 gene expression.

  9. Abscisic Acid Induces Mitogen-Activated Protein Kinase Activation in Barley Aleurone Protoplasts.

    PubMed Central

    Knetsch, MLW.; Wang, M.; Snaar-Jagalska, B. E.; Heimovaara-Dijkstra, S.

    1996-01-01

    Abscisic acid (ABA) induces a rapid and transient mitogen-activated protein (MAP) kinase activation in barley aleurone protoplasts. MAP kinase activity, measured as myelin basic protein phosphorylation by MAP kinase immunoprecipitates, increased after 1 min, peaked after 3 min, and decreased to basal levels after ~5 min of ABA treatment in vivo. Antibodies recognizing phosphorylated tyrosine residues precipitate with myelin basic protein kinase activity that has identical ABA activation characteristics and demonstrate that tyrosine phosphorylation of MAP kinase occurs during activation. The half-maximal concentration of ABA required for MAP kinase activation, 3 x 10-7 M, is very similar to that required for ABA-induced rab16 gene expression. The tyrosine phosphatase inhibitor phenylarsine oxide can completely block ABA-induced MAP kinase activation and rab16 gene expression. These results lead us to conclude that ABA activates MAP kinase via a tyrosine phosphatase and that these steps are a prerequisite for ABA induction of rab16 gene expression. PMID:12239411

  10. Fluctuation driven active molecular transport in passive channel proteins

    NASA Astrophysics Data System (ADS)

    Kosztin, Ioan

    2006-03-01

    Living cells interact with their extracellular environment through the cell membrane, which acts as a protective permeability barrier for preserving the internal integrity of the cell. However, cell metabolism requires controlled molecular transport across the cell membrane, a function that is fulfilled by a wide variety of transmembrane proteins, acting as either passive or active transporters. In this talk it is argued that, contrary to the general belief, in active cell membranes passive and spatially asymmetric channel proteins can act as active transporters by consuming energy from nonequilibrium fluctuations fueled by cell metabolism. This assertion is demonstrated in the case of the E. coli aquaglyceroporin GlpF channel protein, whose high resolution crystal structure is manifestly asymmetric. By calculating the glycerol flux through GlpF within the framework of a stochastic model, it is found that, as a result of channel asymmetry, glycerol uptake driven by a concentration gradient is enhanced significantly in the presence of non-equilibrium fluctuations. Furthermore, the enhancement caused by a ratchet-like mechanism is larger for the outward, i.e., from the cytoplasm to the periplasm, flux than for the inward one, suggesting that the same non-equilibrium fluctuations also play an important role in protecting the interior of the cell against poisoning by excess uptake of glycerol. Preliminary data on water and sugar transport through aquaporin and maltoporin channels, respectively, are indicative of the universality of the proposed nonequilibrium-fluctuation-driven active transport mechanism. This work was supported by grants from the Univ. of Missouri Research Board, the Institute for Theoretical Sciences and the Department of Energy (DOE Contract W-7405-ENG-36), and the National Science Foundation (FIBR-0526854).

  11. Activated protein C mediates a healing phenotype in cultured tenocytes.

    PubMed

    Xue, Meilang; Smith, Margaret M; Little, Christopher B; Sambrook, Philip; March, Lyn; Jackson, Christopher J

    2009-04-01

    Tendon injuries cause considerable morbidity in the general adult population. The tenocytes within the tendon have the full capacity to heal the tendon intrinsically. Activated protein C (APC) plays an important role in coagulation and inflammation and more recently has been shown to promote cutaneous wound healing. In this study we examined whether APC can induce a wound healing phenotype in tenocytes. Sheep tenocytes were treated with APC, endothelial protein C receptor (EPCR) blocking antibody (RCR252) and/or EPCR small interfering (si)RNA. Cell proliferation and migration were measured by crystal violet assay and a scratch wounding assay, respectively. The expression of EPCR, matrix metalloproteinase (MMP)-2, type I collagen and MAP kinase activity were detected by real time PCR, zymography, immunofluorescence, immunohistochemistry and Western blotting. APC stimulated proliferation, MMP-2 activity and type I collagen deposition in a dose-dependent manner and promoted migration of cultured tenocytes. APC dose-dependently stimulated phosphorylated (P)-ERK2 and inhibited P-p38. Interestingly, tenocytes expressed EPCR protein, which was up-regulated by APC. When tenocytes were pre-treated with RCR252 or EPCR siRNA the effect of APC on proliferation, MMP-2 and type 1 collagen synthesis and MAP kinases was blocked. APC promotes the growth, MMP-2 activity, type I collagen deposition and migration of tenocytes. Furthermore, EPCR is expressed by tenocytes and mediates the actions of APC, at least partly by signalling through selective MAP kinases. These data implicate APC as a potential healing agent for injured tendons.

  12. Role of Deleted in Breast Cancer 1 (DBC1) Protein in SIRT1 Deacetylase Activation Induced by Protein Kinase A and AMP-activated Protein Kinase*

    PubMed Central

    Nin, Veronica; Escande, Carlos; Chini, Claudia C.; Giri, Shailendra; Camacho-Pereira, Juliana; Matalonga, Jonathan; Lou, Zhenkun; Chini, Eduardo N.

    2012-01-01

    The NAD+-dependent deacetylase SIRT1 is a key regulator of several aspects of metabolism and aging. SIRT1 activation is beneficial for several human diseases, including metabolic syndrome, diabetes, obesity, liver steatosis, and Alzheimer disease. We have recently shown that the protein deleted in breast cancer 1 (DBC1) is a key regulator of SIRT1 activity in vivo. Furthermore, SIRT1 and DBC1 form a dynamic complex that is regulated by the energetic state of the organism. Understanding how the interaction between SIRT1 and DBC1 is regulated is therefore essential to design strategies aimed to activate SIRT1. Here, we investigated which pathways can lead to the dissociation of SIRT1 and DBC1 and consequently to SIRT1 activation. We observed that PKA activation leads to a fast and transient activation of SIRT1 that is DBC1-dependent. In fact, an increase in cAMP/PKA activity resulted in the dissociation of SIRT1 and DBC1 in an AMP-activated protein kinase (AMPK)-dependent manner. Pharmacological AMPK activation led to SIRT1 activation by a DBC1-dependent mechanism. Indeed, we found that AMPK activators promote SIRT1-DBC1 dissociation in cells, resulting in an increase in SIRT1 activity. In addition, we observed that the SIRT1 activation promoted by PKA and AMPK occurs without changes in the intracellular levels of NAD+. We propose that PKA and AMPK can acutely activate SIRT1 by inducing dissociation of SIRT1 from its endogenous inhibitor DBC1. Our experiments provide new insight on the in vivo mechanism of SIRT1 regulation and a new avenue for the development of pharmacological SIRT1 activators targeted at the dissociation of the SIRT1-DBC1 complex. PMID:22553202

  13. Refolding techniques for recovering biologically active recombinant proteins from inclusion bodies.

    PubMed

    Yamaguchi, Hiroshi; Miyazaki, Masaya

    2014-02-20

    Biologically active proteins are useful for studying the biological functions of genes and for the development of therapeutic drugs and biomaterials in a biotechnology industry. Overexpression of recombinant proteins in bacteria, such as Escherichia coli, often results in the formation of inclusion bodies, which are protein aggregates with non-native conformations. As inclusion bodies contain relatively pure and intact proteins, protein refolding is an important process to obtain active recombinant proteins from inclusion bodies. However, conventional refolding methods, such as dialysis and dilution, are time consuming and, often, recovered yields of active proteins are low, and a trial-and-error process is required to achieve success. Recently, several approaches have been reported to refold these aggregated proteins into an active form. The strategies largely aim at reducing protein aggregation during the refolding procedure. This review focuses on protein refolding techniques using chemical additives and laminar flow in microfluidic chips for the efficient recovery of active proteins from inclusion bodies.

  14. Regulation of mitogen-activated protein kinases by a calcium/calmodulin-dependent protein kinase cascade.

    PubMed Central

    Enslen, H; Tokumitsu, H; Stork, P J; Davis, R J; Soderling, T R

    1996-01-01

    Membrane depolarization of NG108 cells gives rapid (< 5 min) activation of Ca2+/calmodulin-dependent protein kinase IV (CaM-KIV), as well as activation of c-Jun N-terminal kinase (JNK). To investigate whether the Ca2+-dependent activation of mitogen-activated protein kinases (ERK, JNK, and p38) might be mediated by the CaM kinase cascade, we have transfected PC12 cells, which lack CaM-KIV, with constitutively active mutants of CaM kinase kinase and/or CaM-KIV (CaM-KKc and CaM-KIVc, respectively). In the absence of depolarization, CaM-KKc transfection had no effect on Elk-dependent transcription of a luciferase reporter gene, whereas CaM-KIVc alone or in combination with CaM-KKc gave 7- to 10-fold and 60- to 80-fold stimulations, respectively, which were blocked by mitogen-activated protein (MAP) kinase phosphatase cotransfection. When epitope-tagged constructs of MAP kinases were co-transfected with CaM-KKc plus CaM-KIVc, the immunoprecipitated MAP kinases were activated 2-fold (ERK-2) and 7- to 10-fold (JNK-1 and p38). The JNK and p38 pathways were further investigated using specific c-Jun or ATF2-dependent transcriptional assays. We found that c-Jun/ATF2-dependent transcriptions were enhanced 7- to 10-fold by CaM-KIVc and 20- to 30-fold by CaM-KKc plus CaM-KIVc. In the case of the Jun-dependent transcription, this effect was not due to direct phosphorylation of c-Jun by activated CaM-KIV, since transcription was blocked by a dominant-negative JNK and by two MAP kinase phosphatases. Mutation of the phosphorylation site (Thr196) in CaM-KIV, which mediates its activation by CaM-KIV kinase, prevented activation of Elk-1, c-Jun, and ATF2 by the CaM kinase cascade. These results establish a new Ca2+-dependent mechanism for regulating MAP kinase pathways and resultant transcription. Images Fig. 1 Fig. 3 Fig. 4 PMID:8855261

  15. Mycobacteriophage putative GTPase-activating protein can potentiate antibiotics.

    PubMed

    Yan, Shuangquan; Xu, Mengmeng; Duan, Xiangke; Yu, Zhaoxiao; Li, Qiming; Xie, Longxiang; Fan, Xiangyu; Xie, Jianping

    2016-09-01

    The soaring incidences of infection by antimicrobial resistant (AR) pathogens and shortage of effective antibiotics with new mechanisms of action have renewed interest in phage therapy. This scenario is exemplified by resistant tuberculosis (TB), caused by resistant Mycobacterium tuberculosis. Mycobacteriophage SWU1 A321_gp67 encodes a putative GTPase-activating protein. Mycobacterium smegmatis with gp67 overexpression showed changed colony formation and biofilm morphology and supports the efficacy of streptomycin and capreomycin against Mycobacterium. gp67 down-regulated the transcription of genes involved in cell wall and biofilm development. To our knowledge, this is the first report to show that phage protein in addition to lysin or recombination components can synergize with existing antibiotics. Phage components might represent a promising new clue for better antibiotic potentiators. PMID:27345061

  16. Metals in the active site of native protein phosphatase-1.

    PubMed

    Heroes, Ewald; Rip, Jens; Beullens, Monique; Van Meervelt, Luc; De Gendt, Stefan; Bollen, Mathieu

    2015-08-01

    Protein phosphatase-1 (PP1) is a major protein Ser/Thr phosphatase in eukaryotic cells. Its activity depends on two metal ions in the catalytic site, which were identified as manganese in the bacterially expressed phosphatase. However, the identity of the metal ions in native PP1 is unknown. In this study, total reflection X-ray fluorescence (TXRF) was used to detect iron and zinc in PP1 that was purified from rabbit skeletal muscle. Metal exchange experiments confirmed that the distinct substrate specificity of recombinant and native PP1 is determined by the nature of their associated metals. We also found that the iron level associated with native PP1 is decreased by incubation with inhibitor-2, consistent with a function of inhibitor-2 as a PP1 chaperone. PMID:25890482

  17. Cytoprotective-selective activated protein C therapy for ischemic stroke

    PubMed Central

    Mosnier, Laurent O.; Zlokovic, Berislav V.; Griffin, John H.

    2014-01-01

    Summary Despite years of research and efforts to translate stroke research to clinical therapy, ischemic stroke remains a major cause of death, disability, and diminished quality of life. Primary and secondary preventive measures combined with improved quality of care have made significant progress. However, no novel drug for ischemic stroke therapy has been approved in the past decade. Numerous studies have shown beneficial effects of activated protein C (APC) in rodent stroke models. In addition to its natural anticoagulant functions, APC conveys multiple direct cytoprotective effects on many different cell types that involve multiple receptors including protease activated receptor (PAR) 1, PAR3, and the endothelial protein C receptor (EPCR). Application of molecular engineered APC variants with altered selectivity profiles to rodent stroke models demonstrated that the beneficial effects of APC primarily require its cytoprotective activities but not its anticoagulant activities. Extensive basic, preclinical, and clinical research provided a compelling rationale based on strong evidence for translation of APC therapy that has led to the clinical development of the cytoprotective-selective APC variant, 3K3A-APC, for ischemic stroke. Recent identification of non-canonical PAR1 and PAR3 activation by APC that give rise to novel tethered-ligands capable of inducing biased cytoprotective signaling as opposed to the canonical signaling provides a mechanistic explanation for how APC-mediated PAR activation can selectively induce cytoprotective signaling pathways. Collectively, these paradigm-shifting discoveries provide detailed insights into the receptor targets and the molecular mechanisms for neuroprotection by cytoprotective-selective 3K3A-APC, which is currently a biologic drug in clinical trials for ischemic stroke. PMID:25230930

  18. Evidence for protein kinase C-dependent and -independent activation of mitogen-activated protein kinase in T cells: potential role of additional diacylglycerol binding proteins.

    PubMed

    Puente, L G; Stone, J C; Ostergaard, H L

    2000-12-15

    Activation of mitogen-activated protein kinases (MAPK) is a critical signal transduction event for CTL activation, but the signaling mechanisms responsible are not fully characterized. Protein kinase C (PKC) is thought to contribute to MAPK activation following TCR stimulation. We have found that dependence on PKC varies with the method used to stimulate the T cells. Extracellular signal-regulated kinase (ERK) activation in CTL stimulated with soluble cross-linked anti-CD3 is completely inhibited by the PKC inhibitor bisindolylmaleimide (BIM). In contrast, only the later time points in the course of ERK activation are sensitive to BIM when CTL are stimulated with immobilized anti-CD3, a condition that stimulates CTL degranulation. Surprisingly, MAPK activation in response to immobilized anti-CD3 is strongly inhibited at all time points by the diacylglycerol (DAG)-binding domain inhibitor calphostin C implicating the contribution of a DAG-dependent but PKC-independent pathway in the activation of ERK in CTL clones. Chronic exposure to phorbol ester down-regulates the expression of DAG-responsive PKC isoforms; however, this treatment of CTL clones does not inhibit anti-CD3-induced activation of MAPK. Phorbol ester-treated cells have reduced expression of several isoforms of PKC but still express the recently described DAG-binding Ras guanylnucleotide-releasing protein. These results indicate that the late phase of MAPK activation in CTL clones in response to immobilized anti-CD3 stimulation requires PKC while the early phase requires a DAG-dependent, BIM-resistant component.

  19. Protein kinase D activity controls endothelial nitric oxide synthesis.

    PubMed

    Aicart-Ramos, Clara; Sánchez-Ruiloba, Lucía; Gómez-Parrizas, Mónica; Zaragoza, Carlos; Iglesias, Teresa; Rodríguez-Crespo, Ignacio

    2014-08-01

    Vascular endothelial growth factor (VEGF) regulates key functions of the endothelium, such as angiogenesis or vessel repair in processes involving endothelial nitric oxide synthase (eNOS) activation. One of the effector kinases that become activated in endothelial cells upon VEGF treatment is protein kinase D (PKD). Here, we show that PKD phosphorylates eNOS, leading to its activation and a concomitant increase in NO synthesis. Using mass spectrometry, we show that the purified active kinase specifically phosphorylates recombinant eNOS on Ser1179. Treatment of endothelial cells with VEGF or phorbol 12,13-dibutyrate (PDBu) activates PKD and increases eNOS Ser1179 phosphorylation. In addition, pharmacological inhibition of PKD and gene silencing of both PKD1 and PKD2 abrogate VEGF signaling, resulting in a clear diminished migration of endothelial cells in a wound healing assay. Finally, inhibition of PKD in mice results in an almost complete disappearance of the VEGF-induced vasodilatation, as monitored through determination of the diameter of the carotid artery. Hence, our data indicate that PKD is a new regulatory kinase of eNOS in endothelial cells whose activity orchestrates mammalian vascular tone. PMID:24928905

  20. Amygdala kindling alters protein kinase C activity in dentate gyrus.

    PubMed

    Chen, S J; Desai, M A; Klann, E; Winder, D G; Sweatt, J D; Conn, P J

    1992-11-01

    Kindling is a use-dependent form of synaptic plasticity and a widely used model of epilepsy. Although kindling has been widely studied, the molecular mechanisms underlying induction of this phenomenon are not well understood. We determined the effect of amygdala kindling on protein kinase C (PKC) activity in various regions of rat brain. Kindling stimulation markedly elevated basal (Ca(2+)-independent) and Ca(2+)-stimulated phosphorylation of an endogenous PKC substrate (which we have termed P17) in homogenates of dentate gyrus, assayed 2 h after kindling stimulation. The increase in P17 phosphorylation appeared to be due at least in part to persistent PKC activation, as basal PKC activity assayed in vitro using an exogenous peptide substrate was increased in kindled dentate gyrus 2 h after the last kindling stimulation. A similar increase in basal PKC activity was observed in dentate gyrus 2 h after the first kindling stimulation. These results document a kindling-associated persistent PKC activation and suggest that the increased activity of PKC could play a role in the induction of the kindling effect.

  1. Protein glycation inhibitory activity and antioxidant capacity of clove extract.

    PubMed

    Suantawee, Tanyawan; Wesarachanon, Krittaporn; Anantsuphasak, Kanokphat; Daenphetploy, Tanuch; Thien-Ngern, Sroshin; Thilavech, Thavaree; Pasukamonset, Porntip; Ngamukote, Sathaporn; Adisakwattana, Sirichai

    2015-06-01

    Syzygium aromaticum (L.) (clove) is one of the most widely cultivated spices in many tropical countries. The aim of this study was to determine the phytochemical content, the antioxidant properties and the antiglycation properties of aqueous extract of clove against fructose-mediated protein glycation and oxidation. The result showed that the content of total phenolics and flavonoids in clove extract was 239.58 ± 0.70 mg gallic acid equivalents/g dried extract and 65.67 ± 0.01 mg catechin equivalents/g dried extract, respectively. In addition, clove exhibited antioxidant properties including DPPH radical scavenging activity (IC50 = 0.29 ± 0.01 mg/ml), Trolox equivalent antioxidant capacity (4.69 ± 0.03 μmol Trolox equivalents/mg dried extract), ferric reducing antioxidant power (20.55 ± 0.11 μmol ascorbic acid equivalents/mg dried extract), Oxygen radical absorbance capacity (31.12 ± 0.21 μmol Trolox equivalents/mg dried extract), hydroxyl radical scavenging activity (0.15 ± 0.04 mg Trolox equivalents/mg dried extract), and superoxide radical scavenging activity (18.82 ± 0.50 mg Trolox equivalents/mg dried extract). The aqueous extract of clove (0.25-1.00 mg/ml) significantly inhibited the formation of fluorescent advanced glycation end products (AGEs) and non-fluorescent AGEs (N(ɛ)-(carboxymethyl) lysine (CML)) in glycated BSA during 4 weeks of incubation. The extract also markedly prevented oxidation-induced protein damage by decreasing protein carbonyl formation and protecting against the loss of protein thiol group. These results clearly demonstrated that a polyphenol enriched clove extract, owing to its antioxidant, was capable to inhibit the formation of AGEs and protein glycation. The findings might lead to the possibility of using the clove extract for targeting diabetic complications.

  2. Egg Activation at Fertilization by a Soluble Sperm Protein.

    PubMed

    Swann, Karl; Lai, F Anthony

    2016-01-01

    The most fundamental unresolved issue of fertilization is to define how the sperm activates the egg to begin embryo development. Egg activation at fertilization in all species thus far examined is caused by some form of transient increase in the cytoplasmic free Ca(2+) concentration. What has not been clear, however, is precisely how the sperm triggers the large changes in Ca(2+) observed within the egg cytoplasm. Here, we review the studies indicating that the fertilizing sperm stimulates a cytosolic Ca(2+) increase in the egg specifically by delivering a soluble factor that diffuses into the cytosolic space of the egg upon gamete membrane fusion. Evidence is primarily considered in species of eggs where the sperm has been shown to elicit a cytosolic Ca(2+) increase by initiating Ca(2+) release from intracellular Ca(2+) stores. We suggest that our best understanding of these signaling events is in mammals, where the sperm triggers a prolonged series of intracellular Ca(2+) oscillations. The strongest empirical studies to date suggest that mammalian sperm-triggered Ca(2+) oscillations are caused by the introduction of a sperm-specific protein, called phospholipase C-zeta (PLCζ) that generates inositol trisphosphate within the egg. We will discuss the role and mechanism of action of PLCζ in detail at a molecular and cellular level. We will also consider some of the evidence that a soluble sperm protein might be involved in egg activation in nonmammalian species.

  3. A protein tyrosine phosphatase-like protein from baculovirus has RNA 5'-triphosphatase and diphosphatase activities.

    PubMed

    Takagi, T; Taylor, G S; Kusakabe, T; Charbonneau, H; Buratowski, S

    1998-08-18

    The superfamily of protein tyrosine phosphatases (PTPs) includes at least one enzyme with an RNA substrate. We recently showed that the RNA triphosphatase domain of the Caenorhabditis elegans mRNA capping enzyme is related to the PTP enzyme family by sequence similarity and mechanism. The PTP most similar in sequence to the capping enzyme triphosphatase is BVP, a dual-specificity PTP encoded by the Autographa californica nuclear polyhedrosis virus. Although BVP previously has been shown to have modest tyrosine and serine/threonine phosphatase activity, we find that it is much more potent as an RNA 5'-phosphatase. BVP sequentially removes gamma and beta phosphates from the 5' end of triphosphate-terminated RNA, leaving a 5'-monophosphate end. The activity was specific for polynucleotides; nucleotide triphosphates were not hydrolyzed. A mutant protein in which the active site cysteine was replaced with serine was inactive. Three other dual-specificity PTPs (VH1, VHR, and Cdc14) did not exhibit detectable RNA phosphatase activity. Therefore, capping enzyme and BVP are members of a distinct PTP-like subfamily that can remove phosphates from RNA. PMID:9707557

  4. Budding Yeast Silencing Complexes and Regulation of Sir2 Activity by Protein-Protein Interactions

    PubMed Central

    Tanny, Jason C.; Kirkpatrick, Donald S.; Gerber, Scott A.; Gygi, Steven P.; Moazed, Danesh

    2004-01-01

    Gene silencing in the budding yeast Saccharomyces cerevisiae requires the enzymatic activity of the Sir2 protein, a highly conserved NAD-dependent deacetylase. In order to study the activity of native Sir2, we purified and characterized two budding yeast Sir2 complexes: the Sir2/Sir4 complex, which mediates silencing at mating-type loci and at telomeres, and the RENT complex, which mediates silencing at the ribosomal DNA repeats. Analyses of the protein compositions of these complexes confirmed previously described interactions. We show that the assembly of Sir2 into native silencing complexes does not alter its selectivity for acetylated substrates, nor does it allow the deacetylation of nucleosomal histones. The inability of Sir2 complexes to deacetylate nucleosomes suggests that additional factors influence Sir2 activity in vivo. In contrast, Sir2 complexes show significant enhancement in their affinities for acetylated substrates and their sensitivities to the physiological inhibitor nicotinamide relative to recombinant Sir2. Reconstitution experiments showed that, for the Sir2/Sir4 complex, these differences stem from the physical interaction of Sir2 with Sir4. Finally, we provide evidence that the different nicotinamide sensitivities of Sir2/Sir4 and RENT in vitro could contribute to locus-specific differences in how Sir2 activity is regulated in vivo. PMID:15282295

  5. Immersion freezing of ice nucleation active protein complexes

    NASA Astrophysics Data System (ADS)

    Hartmann, S.; Augustin, S.; Clauss, T.; Wex, H.; Šantl-Temkiv, T.; Voigtländer, J.; Niedermeier, D.; Stratmann, F.

    2013-06-01

    Utilising the Leipzig Aerosol Cloud Interaction Simulator (LACIS), the immersion freezing behaviour of droplet ensembles containing monodisperse particles, generated from a Snomax™ solution/suspension, was investigated. Thereto ice fractions were measured in the temperature range between -5 °C to -38 °C. Snomax™ is an industrial product applied for artificial snow production and contains Pseudomonas syringae} bacteria which have long been used as model organism for atmospheric relevant ice nucleation active (INA) bacteria. The ice nucleation activity of such bacteria is controlled by INA protein complexes in their outer membrane. In our experiments, ice fractions increased steeply in the temperature range from about -6 °C to about -10 °C and then levelled off at ice fractions smaller than one. The plateau implies that not all examined droplets contained an INA protein complex. Assuming the INA protein complexes to be Poisson distributed over the investigated droplet populations, we developed the CHESS model (stoCHastic modEl of similar and poiSSon distributed ice nuclei) which allows for the calculation of ice fractions as function of temperature and time for a given nucleation rate. Matching calculated and measured ice fractions, we determined and parameterised the nucleation rate of INA protein complexes exhibiting class III ice nucleation behaviour. Utilising the CHESS model, together with the determined nucleation rate, we compared predictions from the model to experimental data from the literature and found good agreement. We found that (a) the heterogeneous ice nucleation rate expression quantifying the ice nucleation behaviour of the INA protein complex is capable of describing the ice nucleation behaviour observed in various experiments for both, Snomax™ and P. syringae bacteria, (b) the ice nucleation rate, and its temperature dependence, seem to be very similar regardless of whether the INA protein complexes inducing ice nucleation are attached

  6. Keap1-Independent Regulation of Nrf2 Activity by Protein Acetylation and a BET Bromodomain Protein

    PubMed Central

    Chatterjee, Nirmalya; Tian, Min; Spirohn, Kerstin; Boutros, Michael; Bohmann, Dirk

    2016-01-01

    Mammalian BET proteins comprise a family of bromodomain-containing epigenetic regulators with complex functions in chromatin organization and gene regulation. We identified the sole member of the BET protein family in Drosophila, Fs(1)h, as an inhibitor of the stress responsive transcription factor CncC, the fly ortholog of Nrf2. Fs(1)h physically interacts with CncC in a manner that requires the function of its bromodomains and the acetylation of CncC. Treatment of cultured Drosophila cells or adult flies with fs(1)h RNAi or with the BET protein inhibitor JQ1 de-represses CncC transcriptional activity and engages protective gene expression programs. The mechanism by which Fs(1)h inhibits CncC function is distinct from the canonical mechanism that stimulates Nrf2 function by abrogating Keap1-dependent proteasomal degradation. Consistent with the independent modes of CncC regulation by Keap1 and Fs(1)h, combinations of drugs that can specifically target these pathways cause a strong synergistic and specific activation of protective CncC- dependent gene expression and boosts oxidative stress resistance. This synergism might be exploitable for the design of combinatorial therapies to target diseases associated with oxidative stress or inflammation. PMID:27233051

  7. Keap1-Independent Regulation of Nrf2 Activity by Protein Acetylation and a BET Bromodomain Protein.

    PubMed

    Chatterjee, Nirmalya; Tian, Min; Spirohn, Kerstin; Boutros, Michael; Bohmann, Dirk

    2016-05-01

    Mammalian BET proteins comprise a family of bromodomain-containing epigenetic regulators with complex functions in chromatin organization and gene regulation. We identified the sole member of the BET protein family in Drosophila, Fs(1)h, as an inhibitor of the stress responsive transcription factor CncC, the fly ortholog of Nrf2. Fs(1)h physically interacts with CncC in a manner that requires the function of its bromodomains and the acetylation of CncC. Treatment of cultured Drosophila cells or adult flies with fs(1)h RNAi or with the BET protein inhibitor JQ1 de-represses CncC transcriptional activity and engages protective gene expression programs. The mechanism by which Fs(1)h inhibits CncC function is distinct from the canonical mechanism that stimulates Nrf2 function by abrogating Keap1-dependent proteasomal degradation. Consistent with the independent modes of CncC regulation by Keap1 and Fs(1)h, combinations of drugs that can specifically target these pathways cause a strong synergistic and specific activation of protective CncC- dependent gene expression and boosts oxidative stress resistance. This synergism might be exploitable for the design of combinatorial therapies to target diseases associated with oxidative stress or inflammation. PMID:27233051

  8. Interaction of the protein C activation peptide with platelets.

    PubMed

    Martínez-Cruz, Ruth; Canseco, María Del S Pina; Lopez-Martínez, Jael; Cruz, Pedro A Hernández; Pérez-Campos, Eduardo; Cruz, Margarito Martínez; Alva, Félix Córdoba; Majluf-Cruz, Abraham; Zenteno, Edgar; Ruiz-Argüelles, Alejandro

    2007-01-01

    The peptide NH(2)-DTEDQEDQVDPR-COOH is released during activation of protein C zymogen. We measured the effect of a synthetic peptide with an amino acid sequence similar to that of the natural peptide on platelets from healthy individuals using platelet aggregometry. We found that this synthetic peptide inhibits platelet aggregation induced by thrombin; furthermore, it diminishes mobilization of intraplatelet calcium. Molecular docking showed weak interaction between the synthetic peptide and thrombin. Our findings suggest that this synthetic peptide may interact with a receptor located on the platelet cell membrane.

  9. Activity-related redistribution of presynaptic proteins at the active zone.

    PubMed

    Tao-Cheng, J-H

    2006-09-01

    Immunogold labeling distributions of seven presynaptic proteins were quantitatively analyzed under control conditions and after high K+ depolarization in excitatory synapses from dissociated rat hippocampal cultures. Three parallel zones in presynaptic terminals were sampled: zones I and II, each about one synaptic vesicle wide extending from the active zone; and zone III, containing a distal pool of vesicles up to 200 nm from the presynaptic membrane. The distributions of SV2 and synaptophysin, two synaptic vesicle integral membrane proteins, generally followed the distribution of synaptic vesicles, which were typically evenly distributed under control conditions and had a notable depletion in zone III after stimulation. Labels of synapsin I and synuclein, two synaptic vesicle-associated proteins, were similar to each other; both were particularly sparse in zone I under control conditions but showed a prominent enrichment toward the active zone, after stimulation. Labels of Bassoon, Piccolo and RIM 1, three active zone proteins, had very different distribution profiles from one another under control conditions. Bassoon was enriched in zone II, Piccolo and RIM 1 in zone I. After stimulation, Bassoon and Piccolo remained relatively unchanged, but RIM 1 redistributed with a significant decrease in zone I, and increases in zones II and III. These results demonstrate that Bassoon and Piccolo are stable components of the active zone while RIM 1, synapsin I and synuclein undergo dynamic redistribution with synaptic activity.

  10. Interaction of Ca(2+)-dependent activator protein for secretion 1 (CAPS1) with septin family proteins in mouse brain.

    PubMed

    Hosono, Mayu; Shinoda, Yo; Hirano, Touko; Ishizaki, Yasuki; Furuichi, Teiichi; Sadakata, Tetsushi

    2016-03-23

    The Ca(2+)-dependent activator protein for secretion 1 (CAPS1) protein plays a regulatory role in the dense-core vesicle exocytosis pathway. To clarify the functions of this protein in the brain, we searched for novel interaction partners of CAPS1 by mass spectrometry. We identified a specific interaction of CAPS1 with septin family proteins. We also demonstrated that the C-terminal region of the CAPS1 protein binds to part of the deduced GTP-binding domain of septin proteins. It is possible that a tertiary complex of septin, CAPS, and syntaxin contributes to dense-core vesicle trafficking and exocytosis in neurons.

  11. SIRT1 Suppresses Activator Protein-1 Transcriptional Activity and Cyclooxygenase-2 Expression in Macrophages*

    PubMed Central

    Zhang, Ran; Chen, Hou-Zao; Liu, Jin-Jing; Jia, Yu-Yan; Zhang, Zhu-Qin; Yang, Rui-Feng; Zhang, Yuan; Xu, Jing; Wei, Yu-Sheng; Liu, De-Pei; Liang, Chih-Chuan

    2010-01-01

    SIRT1 (Sirtuin type 1), a mammalian orthologue of yeast SIR2 (silent information regulator 2), has been shown to mediate a variety of calorie restriction (CR)-induced physiological events, such as cell fate regulation via deacetylation of the substrate proteins. However, whether SIRT1 deacetylates activator protein-1 (AP-1) to influence its transcriptional activity and target gene expression is still unknown. Here we demonstrate that SIRT1 directly interacts with the basic leucine zipper domains of c-Fos and c-Jun, the major components of AP-1, by which SIRT1 suppressed the transcriptional activity of AP-1. This process requires the deacetylase activity of SIRT1. Notably, SIRT1 reduced the expression of COX-2, a typical AP-1 target gene, and decreased prostaglandin E2 (PGE2) production of peritoneal macrophages (pMΦs). pMΦs with SIRT1 overexpression displayed improved phagocytosis and tumoricidal functions, which are associated with depressed PGE2. Furthermore, SIRT1 protein level was up-regulated in CR mouse pMΦs, whereas elevated SIRT1 decreased COX-2 expression and improved PGE2-related macrophage functions that were reversed following inhibition of SIRT1 deacetylase activity. Thus, our results indicate that SIRT1 may be a mediator of CR-induced macrophage regulation, and its deacetylase activity contributes to the inhibition of AP-1 transcriptional activity and COX-2 expression leading to amelioration of macrophage function. PMID:20042607

  12. Early events of human T lymphocyte activation are associated with type I protein kinase A activity.

    PubMed Central

    Laxminarayana, D; Berrada, A; Kammer, G M

    1993-01-01

    Human T lymphocytes possess both the type I and II isozymes of protein kinase A (PKA). The type I (PKA-I) isozyme is predominantly associated with the plasma membrane, whereas the type II (PKA-II) isozyme is primarily localized to the cytosol. Because the functions of both PKA-I and PKA-II isozymes in the biochemical events of T lymphocyte activation have not been clearly elucidated, we tested the hypothesis that very early events of normal human T lymphocyte activation are mediated by the PKA-I and/or PKA-II isozyme(s). Fresh normal human T cells and a normal human CD4+ T cell line (GK606) activated with anti-CD3-epsilon and recombinant interleukin 1 alpha (rIL-1 alpha) exhibited a peak six- to sevenfold increase of PKA phosphotransferase activity at 5 min that returned to baseline by 60 min. Similarly, both fresh T cells and the T cell line activated by phorbol myristate acetate and ionomycin demonstrated a peak eightfold increase of PKA activity by 15 min that returned toward baseline by 60 min. Chromatographic separation of the PKA isozymes and quantification of phosphotransferase activities after T cell activation by either agonist pair showed preferential activation of the PKA-I isozyme, resulting in a significant reduction in the ratio of PKA-I to PKA-II isozyme activity from 3.1:1-6.2:1 to 1.1:1-3.2:1. PKA-I isozyme activation resulted in the release of free catalytic (C) subunit, an increase in C subunit phosphotransferase activity, and the phosphorylation of T cell plasma membrane-associated proteins, p14, p17, p20, p21, p38, and p48. However, activation of the PKA-I isozyme did not appear to be required for the transcription of IL-2 mRNA, an event necessary for mitosis. These data indicate that ligand-induced T cell activation is associated with rapid activation of the PKA-I, but not PKA-II, isozyme that results in phosphorylation of plasma membrane-associated proteins. The involvement of the PKA-I isozyme during the very early events of T cell

  13. Thermally activated charge transport in microbial protein nanowires

    PubMed Central

    Lampa-Pastirk, Sanela; Veazey, Joshua P.; Walsh, Kathleen A.; Feliciano, Gustavo T.; Steidl, Rebecca J.; Tessmer, Stuart H.; Reguera, Gemma

    2016-01-01

    The bacterium Geobacter sulfurreducens requires the expression of conductive protein filaments or pili to respire extracellular electron acceptors such as iron oxides and uranium and to wire electroactive biofilms, but the contribution of the protein fiber to charge transport has remained elusive. Here we demonstrate efficient long-range charge transport along individual pili purified free of metal and redox organic cofactors at rates high enough to satisfy the respiratory rates of the cell. Carrier characteristics were within the orders reported for organic semiconductors (mobility) and inorganic nanowires (concentration), and resistivity was within the lower ranges reported for moderately doped silicon nanowires. However, the pilus conductance and the carrier mobility decreased when one of the tyrosines of the predicted axial multistep hopping path was replaced with an alanine. Furthermore, low temperature scanning tunneling microscopy demonstrated the thermal dependence of the differential conductance at the low voltages that operate in biological systems. The results thus provide evidence for thermally activated multistep hopping as the mechanism that allows Geobacter pili to function as protein nanowires between the cell and extracellular electron acceptors. PMID:27009596

  14. Thermally activated charge transport in microbial protein nanowires.

    PubMed

    Lampa-Pastirk, Sanela; Veazey, Joshua P; Walsh, Kathleen A; Feliciano, Gustavo T; Steidl, Rebecca J; Tessmer, Stuart H; Reguera, Gemma

    2016-01-01

    The bacterium Geobacter sulfurreducens requires the expression of conductive protein filaments or pili to respire extracellular electron acceptors such as iron oxides and uranium and to wire electroactive biofilms, but the contribution of the protein fiber to charge transport has remained elusive. Here we demonstrate efficient long-range charge transport along individual pili purified free of metal and redox organic cofactors at rates high enough to satisfy the respiratory rates of the cell. Carrier characteristics were within the orders reported for organic semiconductors (mobility) and inorganic nanowires (concentration), and resistivity was within the lower ranges reported for moderately doped silicon nanowires. However, the pilus conductance and the carrier mobility decreased when one of the tyrosines of the predicted axial multistep hopping path was replaced with an alanine. Furthermore, low temperature scanning tunneling microscopy demonstrated the thermal dependence of the differential conductance at the low voltages that operate in biological systems. The results thus provide evidence for thermally activated multistep hopping as the mechanism that allows Geobacter pili to function as protein nanowires between the cell and extracellular electron acceptors. PMID:27009596

  15. Perivascular fat, AMP-activated protein kinase and vascular diseases

    PubMed Central

    Almabrouk, T A M; Ewart, M A; Salt, I P; Kennedy, S

    2014-01-01

    Perivascular adipose tissue (PVAT) is an active endocrine and paracrine organ that modulates vascular function, with implications for the pathophysiology of cardiovascular disease (CVD). Adipocytes and stromal cells contained within PVAT produce mediators (adipokines, cytokines, reactive oxygen species and gaseous compounds) with a range of paracrine effects modulating vascular smooth muscle cell contraction, proliferation and migration. However, the modulatory effect of PVAT on the vascular system in diseases, such as obesity, hypertension and atherosclerosis, remains poorly characterized. AMP-activated protein kinase (AMPK) regulates adipocyte metabolism, adipose biology and vascular function, and hence may be a potential therapeutic target for metabolic disorders such as type 2 diabetes mellitus (T2DM) and the vascular complications associated with obesity and T2DM. The role of AMPK in PVAT or the actions of PVAT have yet to be established, however. Activation of AMPK by pharmacological agents, such as metformin and thiazolidinediones, may modulate the activity of PVAT surrounding blood vessels and thereby contribute to their beneficial effect in cardiometabolic diseases. This review will provide a current perspective on how PVAT may influence vascular function via AMPK. We will also attempt to demonstrate how modulating AMPK activity using pharmacological agents could be exploited therapeutically to treat cardiometabolic diseases. PMID:24490856

  16. Comparative Analysis of Protein Tyrosine Phosphatases Regulating Microglial Activation

    PubMed Central

    Song, Gyun Jee; Kim, Jaehong; Kim, Jong-Heon; Song, Seungeun; Park, Hana; Zhang, Zhong-Yin

    2016-01-01

    Protein tyrosine phosphatases (PTPs) are key regulatory factors in inflammatory signaling pathways. Although PTPs have been extensively studied, little is known about their role in neuroinflammation. In the present study, we examined the expression of 6 different PTPs (PTP1B, TC-PTP, SHP2, MEG2, LYP, and RPTPβ) and their role in glial activation and neuroinflammation. All PTPs were expressed in brain and glia. The expression of PTP1B, SHP2, and LYP was enhanced in the inflamed brain. The expression of PTP1B, TC-PTP, and LYP was increased after treating microglia cells with lipopolysaccharide (LPS). To examine the role of PTPs in microglial activation and neuroinflammation, we used specific pharmacological inhibitors of PTPs. Inhibition of PTP1B, TC-PTP, SHP2, LYP, and RPTPβ suppressed nitric oxide production in LPS-treated microglial cells in a dose-dependent manner. Furthermore, intracerebroventricular injection of PTP1B, TC-PTP, SHP2, and RPTPβ inhibitors downregulated microglial activation in an LPS-induced neuroinflammation model. Our results indicate that multiple PTPs are involved in regulating microglial activation and neuroinflammation, with different expression patterns and specific functions. Thus, PTP inhibitors can be exploited for therapeutic modulation of microglial activation in neuroinflammatory diseases. PMID:27790059

  17. Physical activity and high-sensitivity C-reactive protein.

    PubMed

    Plaisance, Eric P; Grandjean, Peter W

    2006-01-01

    Cardiovascular disease (CVD) remains one of the leading causes of death and disability in developed countries around the world despite the documented success of lifestyle and pharmacological interventions. This illustrates the multifactorial nature of atherosclerosis and the use of novel inflammatory markers as an adjunct to risk factor reduction strategies. As evidence continues to accumulate that inflammation is involved in all stages of the development and progression of atherosclerosis, markers of inflammation such as high-sensitivity C-reactive protein (CRP) may provide additional information regarding the biological status of the atherosclerotic lesion. Recent investigations suggest that physical activity reduces CRP levels. Higher levels of physical activity and cardiorespiratory fitness are consistently associated with 6-35% lower CRP levels. Longitudinal training studies that have demonstrated reductions in CRP concentrations range from 16% to 41%, an effect that may be independent of baseline levels of CRP, body composition or weight loss. The average change in CRP associated with physical activity appears to be at least as good, if not better, than currently prescribed pharmacological interventions in similar populations. The primary purpose of this review will be to present evidence from both cross-sectional and longitudinal investigations that physical activity lowers CRP levels in a dose-response manner. Finally, this review will examine factors such as body composition, sex, blood sample timing, diet and smoking, which may influence the CRP response to physical activity. PMID:16646631

  18. Structure and Activity of Tryptophan-rich TSPO Translocator Proteins

    PubMed Central

    Guo, Youzhong; Kalathur, Ravi C.; Liu, Qun; Kloss, Brian; Bruni, Renato; Ginter, Christopher; Kloppmann, Edda; Rost, Burkhard; Hendrickson, Wayne A.

    2015-01-01

    TSPO translocator proteins bind steroids and porphyrins, and they are implicated in many human diseases, for which they serve as biomarkers and therapeutic targets. TSPOs have tryptophan-rich sequences that are fhighly conserved from bacteria to mammals. We report crystal structures for Bacillus cereus TSPO (BcTSPO) down to 1.7Å resolution, including a complex with the benzodiazepine-like inhibitor PK11195. We also describe BcTSPO-mediated protoporphyrin IX (PpIX) reactions, including catalytic degradation to a previously undescribed heme derivative. We used structure-inspired mutations to investigate reaction mechanisms, and we showed that TSPOs from Xenopus and man have similar PpIX-directed activities. Although TSPOs have been regarded as transporters, the catalytic activity in PpIX degradation suggests physiological importance for TSPOs in protection against oxidative stress. PMID:25635100

  19. TALE proteins bind to both active and inactive chromatin.

    PubMed

    Scott, James N F; Kupinski, Adam P; Kirkham, Christopher M; Tuma, Roman; Boyes, Joan

    2014-02-15

    TALE (transcription activator-like effector) proteins can be tailored to bind to any DNA sequence of choice and thus are of immense utility for genome editing and the specific delivery of transcription activators. However, to perform these functions, they need to occupy their sites in chromatin. In the present study, we have systematically assessed TALE binding to chromatin substrates and find that in vitro TALEs bind to their target site on nucleosomes at the more accessible entry/exit sites, but not at the nucleosome dyad. We show further that in vivo TALEs bind to transcriptionally repressed chromatin and that transcription increases binding by only 2-fold. These data therefore imply that TALEs are likely to bind to their target in vivo even at inactive loci.

  20. Small Molecule Inhibitors Targeting Activator Protein 1 (AP-1)

    PubMed Central

    2015-01-01

    Activator protein 1 (AP-1) is a pivotal transcription factor that regulates a wide range of cellular processes including proliferation, apoptosis, differentiation, survival, cell migration, and transformation. Accumulating evidence supports that AP-1 plays an important role in several severe disorders including cancer, fibrosis, and organ injury, as well as inflammatory disorders such as asthma, psoriasis, and rheumatoid arthritis. AP-1 has emerged as an actively pursued drug discovery target over the past decade. Excitingly, a selective AP-1 inhibitor T-5224 (51) has been investigated in phase II human clinical trials. Nevertheless, no effective AP-1 inhibitors have yet been approved for clinical use. Despite significant advances achieved in understanding AP-1 biology and function, as well as the identification of small molecules modulating AP-1 associated signaling pathways, medicinal chemistry efforts remain an urgent need to yield selective and efficacious AP-1 inhibitors as a viable therapeutic strategy for human diseases. PMID:24831826

  1. Enhancing the Activity of a Protein by Stereospecific Unfolding

    PubMed Central

    Hua, Qing-xin; Xu, Bin; Huang, Kun; Hu, Shi-Quan; Nakagawa, Satoe; Jia, Wenhua; Wang, Shuhua; Whittaker, Jonathan; Katsoyannis, Panayotis G.; Weiss, Michael A.

    2009-01-01

    A central tenet of molecular biology holds that the function of a protein is mediated by its structure. An inactive ground-state conformation may nonetheless be enjoined by the interplay of competing biological constraints. A model is provided by insulin, well characterized at atomic resolution by x-ray crystallography. Here, we demonstrate that the activity of the hormone is enhanced by stereospecific unfolding of a conserved structural element. A bifunctional β-strand mediates both self-assembly (within β-cell storage vesicles) and receptor binding (in the bloodstream). This strand is anchored by an invariant side chain (PheB24); its substitution by Ala leads to an unstable but native-like analog of low activity. Substitution by d-Ala is equally destabilizing, and yet the protein diastereomer exhibits enhanced activity with segmental unfolding of the β-strand. Corresponding photoactivable derivatives (containing l- or d-para-azido-Phe) cross-link to the insulin receptor with higher d-specific efficiency. Aberrant exposure of hydrophobic surfaces in the analogs is associated with accelerated fibrillation, a form of aggregation-coupled misfolding associated with cellular toxicity. Conservation of PheB24, enforced by its dual role in native self-assembly and induced fit, thus highlights the implicit role of misfolding as an evolutionary constraint. Whereas classical crystal structures of insulin depict its storage form, signaling requires engagement of a detachable arm at an extended receptor interface. Because this active conformation resembles an amyloidogenic intermediate, we envisage that induced fit and self-assembly represent complementary molecular adaptations to potential proteotoxicity. The cryptic threat of misfolding poses a universal constraint in the evolution of polypeptide sequences. PMID:19321436

  2. Inhibition of Type III Interferon Activity by Orthopoxvirus Immunomodulatory Proteins

    PubMed Central

    2010-01-01

    The type III interferon (IFN) family elicits an antiviral response that is nearly identical to that evoked by IFN-α/β. However, these cytokines (known as IFN-λ1, 2, and 3) signal through a distinct receptor, and thus may be resistant to the evasion strategies used by some viruses to avoid the IFN-α/β response. Orthopoxviruses are highly resistant to IFN-α/β because they encode well-characterized immunomodulatory proteins that inhibit IFN activity. These include a secreted receptor (B18R) that neutralizes IFN-α/β, and a cytoplasmic protein (E3L) that blocks IFN-α/β effector functions in infected cells. We therefore determined the ability of these immunomodulators to abrogate the IFN-λ–induced antiviral response. We found that (i) vaccinia virus (VACV) replication is resistant to IFN-λ antiviral activity; (ii) neither VACV B18R nor the variola virus homolog B20R neutralizes IFN-λ; (iii) VACV E3L inhibits the IFN-λ–mediated antiviral response through a PKR-dependent pathway; (iv) VACV infection inhibits IFN-λR–mediated signal transduction and gene expression. These results demonstrate differential sensitivity of IFN-λ to multiple distinct evasion mechanisms employed by a single virus. PMID:20038204

  3. Proteins with RNA Chaperone Activity: A World of Diverse Proteins with a Common Task—Impediment of RNA Misfolding

    PubMed Central

    Semrad, Katharina

    2011-01-01

    Proteins with RNA chaperone activity are ubiquitous proteins that play important roles in cellular mechanisms. They prevent RNA from misfolding by loosening misfolded structures without ATP consumption. RNA chaperone activity is studied in vitro and in vivo using oligonucleotide- or ribozyme-based assays. Due to their functional as well as structural diversity, a common chaperoning mechanism or universal motif has not yet been identified. A growing database of proteins with RNA chaperone activity has been established based on evaluation of chaperone activity via the described assays. Although the exact mechanism is not yet understood, it is more and more believed that disordered regions within proteins play an important role. This possible mechanism and which proteins were found to possess RNA chaperone activity are discussed here. PMID:21234377

  4. Biodegradable nanoparticles for protein delivery: analysis of preparation conditions on particle morphology and protein loading, activity and sustained release properties.

    PubMed

    Coleman, Jason; Lowman, Anthony

    2012-01-01

    PLGA particles have been extensively used as a sustained drug-delivery system, but there are multiple drawbacks when delivering proteins. The focus of this work is to address the most significant disadvantages to the W/O/W double emulsion procedure and demonstrate that simple changes to this procedure can have significant changes to particle size and dispersity and considerable improvements to protein loading, activity and sustained active protein release. A systematic approach was taken to analyze the effects of the following variables: solvent miscibility (dichloromethane (DCM), ethyl acetate, acetone), homogenization speed (10 000-25 000 rpm), PLGA concentration (10-30 mg/ml) and additives in both the organic (sucrose acetate isobutyrate (SAIB)) and aqueous (bovine serum albumin (BSA)) phases. Increasing solvent miscibility decreased particle size, dispersity and protein denaturation, while maintaining adequate protein loading. Increasing solvent miscibility also lowered the impact of homogenization on particle size and dispersity and protein activity. Changes to PLGA concentration demonstrated a minimum impact on particle size and dispersity, but showed an inverse relationship between protein encapsulation efficiency and particle protein weight percent. Most particles tested provided sustained release of active protein over 60 days. Increasing solvent miscibility resulted in increases in the percent of active protein released. When subjected to synthesis conditions with DCM as the solvent, BSA as a stabilizer resulted in the maximum stabilization of protein at a concentration of 100 mg/ml. At this concentration, BSA allowed for increases in the total amount of active protein delivered for all three solvents. The benefit of SAIB was primarily increased protein loading.

  5. Protein tyrosine kinase and mitogen-activated protein kinase signalling pathways contribute to differences in heterophil-mediated innate immune responsiveness between two lines of broilers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein tyrosine phosphorylation mediates signal transduction of cellular processes, with protein tyrosine kinases (PTKs) regulating virtually all signaling events. The mitogen-activated protein kinase (MAPK) super-family consists of three conserved pathways that convert receptor activation into ce...

  6. PPAR-β/δ activation promotes phospholipid transfer protein expression.

    PubMed

    Chehaibi, Khouloud; Cedó, Lídia; Metso, Jari; Palomer, Xavier; Santos, David; Quesada, Helena; Naceur Slimane, Mohamed; Wahli, Walter; Julve, Josep; Vázquez-Carrera, Manuel; Jauhiainen, Matti; Blanco-Vaca, Francisco; Escolà-Gil, Joan Carles

    2015-03-15

    The peroxisome proliferator-activated receptor (PPAR)-β/δ has emerged as a promising therapeutic target for treating dyslipidemia, including beneficial effects on HDL cholesterol (HDL-C). In the current study, we determined the effects of the PPAR-β/δ agonist GW0742 on HDL composition and the expression of liver HDL-related genes in mice and cultured human cells. The experiments were carried out in C57BL/6 wild-type, LDL receptor (LDLR)-deficient mice and PPAR-β/δ-deficient mice treated with GW0742 (10mg/kg/day) or a vehicle solution for 14 days. GW0742 upregulated liver phospholipid transfer protein (Pltp) gene expression and increased serum PLTP activity in mice. When given to wild-type mice, GW0742 significantly increased serum HDL-C and HDL phospholipids; GW0742 also raised serum potential to generate preβ-HDL formation. The GW0742-mediated effects on liver Pltp expression and serum enzyme activity were completely abolished in PPAR-β/δ-deficient mice. GW0742 also stimulated PLTP mRNA expression in mouse J774 macrophages, differentiated human THP-1 macrophages and human hepatoma Huh7. Collectively, our findings demonstrate a common transcriptional upregulation by GW0742-activated PPAR-β/δ of Pltp expression in cultured cells and in mouse liver resulting in enhanced serum PLTP activity. Our results also indicate that PPAR-β/δ activation may modulate PLTP-mediated preβ-HDL formation and macrophage cholesterol efflux.

  7. A Variable Light Domain Fluorogen Activating Protein Homodimerizes To Activate Dimethylindole Red

    SciTech Connect

    Senutovitch, Nina; Stanfield, Robyn L.; Bhattacharyya, Shantanu; Rule, Gordon S.; Wilson, Ian A.; Armitage, Bruce A.; Waggoner, Alan S.; Berget, Peter B.

    2012-07-11

    Novel fluorescent tools such as green fluorescent protein analogues and fluorogen activating proteins (FAPs) are useful in biological imaging for tracking protein dynamics in real time with a low fluorescence background. FAPs are single-chain variable fragments (scFvs) selected from a yeast surface display library that produce fluorescence upon binding a specific dye or fluorogen that is normally not fluorescent when present in solution. FAPs generally consist of human immunoglobulin variable heavy (V{sub H}) and variable light (V{sub L}) domains covalently attached via a glycine- and serine-rich linker. Previously, we determined that the yeast surface clone, V{sub H}-V{sub L} M8, could bind and activate the fluorogen dimethylindole red (DIR) but that the fluorogen activation properties were localized to the M8V{sub L} domain. We report here that both nuclear magnetic resonance and X-ray diffraction methods indicate the M8V{sub L} forms noncovalent, antiparallel homodimers that are the fluorogen activating species. The M8V{sub L} homodimers activate DIR by restriction of internal rotation of the bound dye. These structural results, together with directed evolution experiments with both V{sub H}-V{sub L} M8 and M8V{sub L}, led us to rationally design tandem, covalent homodimers of M8V{sub L} domains joined by a flexible linker that have a high affinity for DIR and good quantum yields.

  8. Sustained mitogen-activated protein kinase activation reprograms defense metabolism and phosphoprotein profile in Arabidopsis thaliana

    PubMed Central

    Lassowskat, Ines; Böttcher, Christoph; Eschen-Lippold, Lennart; Scheel, Dierk; Lee, Justin

    2014-01-01

    Mitogen-activated protein kinases (MAPKs) target a variety of protein substrates to regulate cellular signaling processes in eukaryotes. In plants, the number of identified MAPK substrates that control plant defense responses is still limited. Here, we generated transgenic Arabidopsis thaliana plants with an inducible system to simulate in vivo activation of two stress-activated MAPKs, MPK3, and MPK6. Metabolome analysis revealed that this artificial MPK3/6 activation (without any exposure to pathogens or other stresses) is sufficient to drive the production of major defense-related metabolites, including various camalexin, indole glucosinolate and agmatine derivatives. An accompanying (phospho)proteome analysis led to detection of hundreds of potential phosphoproteins downstream of MPK3/6 activation. Besides known MAPK substrates, many candidates on this list possess typical MAPK-targeted phosphosites and in many cases, the corresponding phosphopeptides were detected by mass spectrometry. Notably, several of these putative phosphoproteins have been reported to be associated with the biosynthesis of antimicrobial defense substances (e.g., WRKY transcription factors and proteins encoded by the genes from the “PEN” pathway required for penetration resistance to filamentous pathogens). Thus, this work provides an inventory of candidate phosphoproteins, including putative direct MAPK substrates, for future analysis of MAPK-mediated defense control. (Proteomics data are available with the identifier PXD001252 via ProteomeXchange, http://proteomecentral.proteomexchange.org). PMID:25368622

  9. Targeted Mutagenesis and Combinatorial Library Screening Enables Control of Protein Orientation on Surfaces and Increased Activity of Adsorbed Proteins.

    PubMed

    Cruz-Teran, Carlos A; Carlin, Kevin B; Efimenko, Kirill; Genzer, Jan; Rao, Balaji M

    2016-08-30

    While nonspecific adsorption is widely used for immobilizing proteins on solid surfaces, the random nature of protein adsorption may reduce the activity of immobilized proteins due to occlusion of the active site. We hypothesized that the orientation a protein assumes on a given surface can be controlled by systematically introducing mutations into a region distant from its active site, thereby retaining activity of the immobilized protein. To test this hypothesis, we generated a combinatorial protein library by randomizing six targeted residues in a binding protein derived from highly stable, nonimmunoglobulin Sso7d scaffold; mutations were targeted in a region that is distant from the binding site. This library was screened to isolate binders that retain binding to its cognate target (chicken immunoglobulin Y, cIgY) as well as exhibit adsorption on unmodified silica at pH 7.4 and high ionic strength conditions. A single mutant, Sso7d-2B5, was selected for further characterization. Sso7d-2B5 retained binding to cIgY with an apparent dissociation constant similar to that of the parent protein; both mutant and parent proteins saturated the surface of silica with similar densities. Strikingly, however, silica beads coated with Sso7d-2B5 could achieve up to 7-fold higher capture of cIgY than beads coated with the parent protein. These results strongly suggest that mutations introduced in Sso7d-2B5 alter its orientation relative to the parent protein, when adsorbed on silica surfaces. Our approach also provides a generalizable strategy for introducing mutations in proteins so as to improve their activity upon immobilization, and has direct relevance to development of protein-based biosensors and biocatalysts. PMID:27490089

  10. Stimulation of Periodontal Ligament Stem Cells by Dentin Matrix Protein 1 Activates Mitogen-Activated Protein Kinase and Osteoblast Differentiation

    PubMed Central

    Chandrasekaran, Sangeetha; Ramachandran, Amsaveni; Eapen, Asha; George, Anne

    2013-01-01

    Background Periodontitis can ultimately result in tooth loss. Many natural and synthetic materials have been tried to achieve periodontal regeneration, but the results remain variable and unpredictable. We hypothesized that exogenous treatment with dentin matrix protein 1 (DMP1) activates specific genes and results in phenotypic and functional changes in human periodontal ligament stem cells (hPDLSCs). Methods hPDLSCs were isolated from extracted teeth and cultured in the presence or absence of DMP1. Quantitative polymerase chain reactions were performed to analyze the expression of several genes involved in periodontal regeneration. hPDLSCs were also processed for immunocytochemical and Western blot analysis using phosphorylated extracellular signal-regulated kinase (pERK) and ERK antibodies. Alkaline phosphatase and von Kossa staining were performed to characterize the differentiation of hPDLSCs into osteoblasts. Field emission scanning electron microscopic analysis of the treated and control cell cultures were also performed. Results Treatment with DMP1 resulted in the upregulation of genes, such as matrix metalloproteinase-2, alkaline phosphatase, and transforming growth factor β1. Activation of ERK mitogen-activated protein kinase signaling pathway and translocation of pERK from the cytoplasm to the nucleus was observed. Overall, DMP1-treated cells showed increased expression of alkaline phosphatase, increased matrix, and mineralized nodule formation when compared with untreated controls. Conclusion DMP1 can orchestrate a coordinated expression of genes and phenotypic changes in hPDLSCs by activation of the ERK signaling pathway, which may provide a valuable strategy for tissue engineering approaches in periodontal regeneration. PMID:22612367

  11. Leishmania amazonensis: PKC-like protein kinase modulates the (Na++K+)ATPase activity.

    PubMed

    Almeida-Amaral, Elmo Eduardo de; Caruso-Neves, Celso; Lara, Lucienne Silva; Pinheiro, Carla Mônica; Meyer-Fernandes, José Roberto

    2007-08-01

    The present study aimed to identify the presence of protein kinase C-like (PKC-like) in Leishmania amazonensis and to elucidate its possible role in the modulation of the (Na(+)+K(+))ATPase activity. Immunoblotting experiments using antibody against a consensus sequence (Ac 543-549) of rabbit protein kinase C (PKC) revealed the presence of a protein kinase of 80 kDa in L. amazonensis. Measurements of protein kinase activity showed the presence of both (Ca(2+)-dependent) and (Ca(2+)-independent) protein kinase activity in plasma membrane and cytosol. Phorbol ester (PMA) activation of the Ca(2+)-dependent protein kinase stimulated the (Na(+)+K(+))ATPase activity, while activation of the Ca(2+)-independent protein kinase was inhibitory. Both effects of protein kinase on the (Na(+)+K(+))ATPase of the plasma membrane were lower than that observed in intact cells. PMA induced the translocation of protein kinase from cytosol to plasma membrane, indicating that the maximal effect of protein kinase on the (Na(+)+K(+))ATPase activity depends on the synergistic action of protein kinases from both plasma membrane and cytosol. This is the first demonstration of a protein kinase activated by PMA in L. amazonensis and the first evidence for a possible role in the regulation of the (Na(+)+K(+))ATPase activity in this trypanosomatid. Modulation of the (Na(+)+K(+))ATPase by protein kinase in a trypanosomatid opens up new possibilities to understand the regulation of ion homeostasis in this parasite. PMID:17475255

  12. Combination of MS protein identification and bioassay of chromatographic fractions to identify biologically active substances from complex protein sources.

    PubMed

    Kuromitsu, Sadao; Yokota, Hiroyuki; Hiramoto, Masashi; Yuri, Masatoshi; Naitou, Masanori; Nakamura, Naoto; Kawabata, Shigeki; Kobori, Masato; Katoh, Masao; Furuchi, Kiyoshi; Mita, Haruhisa; Yamada, Tetsuo

    2009-06-01

    Purification of biologically active proteins from complex biological sources is a difficult task, usually requiring large amounts of sample and many separation steps. We found an active substance in a serum response element-dependent luciferase reporter gene bioassay in interstitial cystitis urine that we attempted to purify with column chromatography and the bioassay. With anion-exchange Mono Q and C4 reversed-phase columns, apparently sharp active peaks were obtained. However, more than 20 kinds of proteins were identified from the active fractions with MS, indicating that the purification was not complete. As further purification was difficult, we chose a candidate molecule by means of studying the correlation between MS protein identification scores and bioassay responses of chromatographic fractions near the active peaks. As a result, epidermal growth factor (EGF) was nominated as a candidate molecule among the identified proteins because the elution profile of EGF was consistent with that of the bioassay, and the correlation coefficient of EGF between MS protein identification scores and bioassay responses was the highest among all the identified proteins. With recombinant EGF and anti-EGF and anti-EGF receptor antibodies, EGF was confirmed to be the desired substance in interstitial cystitis urine. This approach required only 20 ml of urine sample and two column chromatographic steps. The combination of MS protein identification and bioassay of chromatographic fractions may be useful for identifying biologically active substances from complex protein sources.

  13. Extracellular protein analysis of activated sludge and their functions in wastewater treatment plant by shotgun proteomics

    PubMed Central

    Zhang, Peng; Shen, Yu; Guo, Jin-Song; Li, Chun; Wang, Han; Chen, You-Peng; Yan, Peng; Yang, Ji-Xiang; Fang, Fang

    2015-01-01

    In this work, proteins in extracellular polymeric substances extracted from anaerobic, anoxic and aerobic sludges of wastewater treatment plant (WWTP) were analyzed to probe their origins and functions. Extracellular proteins in WWTP sludges were identified using shotgun proteomics, and 130, 108 and 114 proteins in anaerobic, anoxic and aerobic samples were classified, respectively. Most proteins originated from cell and cell part, and their most major molecular functions were catalytic activity and binding activity. The results exhibited that the main roles of extracellular proteins in activated sludges were multivalence cations and organic molecules binding, as well as in catalysis and degradation. The catalytic activity proteins were more widespread in anaerobic sludge compared with those in anoxic and aerobic sludges. The structure difference between anaerobic and aerobic sludges could be associated with their catalytic activities proteins. The results also put forward a relation between the macro characteristics of activated sludges and micro functions of extracellular proteins in biological wastewater treatment process. PMID:26160685

  14. Integrins activate trimeric G proteins via the nonreceptor protein GIV/Girdin

    PubMed Central

    Leyme, Anthony; Marivin, Arthur; Perez-Gutierrez, Lorena; Nguyen, Lien T.

    2015-01-01

    Signal transduction via integrins and G protein–coupled receptors is critical to control cell behavior. These two receptor classes have been traditionally believed to trigger distinct and independent signaling cascades in response to extracellular cues. Here, we report a novel mechanism of integrin signaling that requires activation of the trimeric G protein Gαi by the nonreceptor guanine nucleotide exchange factor (GEF) GIV (also known as Girdin), a metastasis-associated protein. We demonstrate that GIV enhances integrin-dependent cell responses upon extracellular matrix stimulation and makes tumor cells more invasive. These responses include remodeling of the actin cytoskeleton and PI3K-dependent signaling, resulting in enhanced haptotaxis and invasion. We show that both GIV and its substrate Gαi3 are recruited to active integrin complexes and that tumor cells engineered to express GEF-deficient GIV fail to transduce integrin signals into proinvasive responses via a Gβγ-PI3K axis. Our discoveries delineate a novel mechanism by which integrin signaling is rewired during metastasis to result in increased tumor invasiveness. PMID:26391662

  15. The total protein content, protein fractions and proteases activities of drone prepupae of Apis mellifera due to varrosis.

    PubMed

    Zółtowska, Krystyna; Lipiński, Zbigniew; Dmitryjuk, Małgorzata

    2005-01-01

    The proteins level and activities of acid and alkaline proteases in whole body extracts of drone prepupae of Apis mellifera naturally infested with Varroa destructor were studied. The infested and a non-infested group did not differ significantly in their total protein content. However, some differences in protein profiles were found. A lack of three protein fractions of moderate and lower molecular weight in infested prepupae was noted. Moreover, some differences in the quantity of protein in most of the fractions were observed. The activity of acid proteases from infested prepupae was lower (p < 0.05) compared with the activity of these proteases from the non-infested one group. The infested drone had higher activity of alkaline proteases than non-infested but this difference was not statisticaly significant.

  16. The total protein content, protein fractions and proteases activities of drone prepupae of Apis mellifera due to varrosis.

    PubMed

    Zółtowska, Krystyna; Lipiński, Zbigniew; Dmitryjuk, Małgorzata

    2005-01-01

    The proteins level and activities of acid and alkaline proteases in whole body extracts of drone prepupae of Apis mellifera naturally infested with Varroa destructor were studied. The infested and a non-infested group did not differ significantly in their total protein content. However, some differences in protein profiles were found. A lack of three protein fractions of moderate and lower molecular weight in infested prepupae was noted. Moreover, some differences in the quantity of protein in most of the fractions were observed. The activity of acid proteases from infested prepupae was lower (p < 0.05) compared with the activity of these proteases from the non-infested one group. The infested drone had higher activity of alkaline proteases than non-infested but this difference was not statisticaly significant. PMID:16841690

  17. Annexin proteins PP4 and PP4-X. Comparative characterization of biological activities of placental and recombinant proteins.

    PubMed Central

    Römisch, J; Grote, M; Weithmann, K U; Heimburger, N; Amann, E

    1990-01-01

    The human placental proteins PP4 and PP4-X, belonging to the annexin protein family, were expressed in Escherichia coli at high yield. The proteins were purified to homogeneity. The physicochemical parameters of the recombinant proteins were determined and compared with those of their natural placental counterparts. Except for a minor change in the pI, the proteins appeared to be indistinguishable by several criteria. Both recombinant PP4 and recombinant PP4-X were biologically active in a thromboplastin inhibition test and in a phospholipase A2 inhibition test. Images Fig. 2. Fig. 3. Fig. 4. PMID:2148260

  18. Functional analysis of oxidative stress-activated mitogen-activated protein kinase cascade in plants

    PubMed Central

    Kovtun, Yelena; Chiu, Wan-Ling; Tena, Guillaume; Sheen, Jen

    2000-01-01

    Despite the recognition of H2O2 as a central signaling molecule in stress and wounding responses, pathogen defense, and regulation of cell cycle and cell death, little is known about how the H2O2 signal is perceived and transduced in plant cells. We report here that H2O2 is a potent activator of mitogen-activated protein kinases (MAPKs) in Arabidopsis leaf cells. Using epitope tagging and a protoplast transient expression assay, we show that H2O2 can activate a specific Arabidopsis mitogen-activated protein kinase kinase kinase, ANP1, which initiates a phosphorylation cascade involving two stress MAPKs, AtMPK3 and AtMPK6. Constitutively active ANP1 mimics the H2O2 effect and initiates the MAPK cascade that induces specific stress-responsive genes, but it blocks the action of auxin, a plant mitogen and growth hormone. The latter observation provides a molecular link between oxidative stress and auxin signal transduction. Finally, we show that transgenic tobacco plants that express a constitutively active tobacco ANP1 orthologue, NPK1, display enhanced tolerance to multiple environmental stress conditions without activating previously described drought, cold, and abscisic acid signaling pathways. Thus, manipulation of key regulators of an oxidative stress signaling pathway, such as ANP1/NPK1, provides a strategy for engineering multiple stress tolerance that may greatly benefit agriculture. PMID:10717008

  19. Activation of AMP-activated protein kinase by tributyltin induces neuronal cell death

    SciTech Connect

    Nakatsu, Yusuke; Kotake, Yaichiro Hino, Atsuko; Ohta, Shigeru

    2008-08-01

    AMP-activated protein kinase (AMPK), a member of the metabolite-sensing protein kinase family, is activated by energy deficiency and is abundantly expressed in neurons. The environmental pollutant, tributyltin chloride (TBT), is a neurotoxin, and has been reported to decrease cellular ATP in some types of cells. Therefore, we investigated whether TBT activates AMPK, and whether its activation contributes to neuronal cell death, using primary cultures of cortical neurons. Cellular ATP levels were decreased 0.5 h after exposure to 500 nM TBT, and the reduction was time-dependent. It was confirmed that most neurons in our culture system express AMPK, and that TBT induced phosphorylation of AMPK. Compound C, an AMPK inhibitor, reduced the neurotoxicity of TBT, suggesting that AMPK is involved in TBT-induced cell death. Next, the downstream target of AMPK activation was investigated. Nitric oxide synthase, p38 phosphorylation and Akt dephosphorylation were not downstream of TBT-induced AMPK activation because these factors were not affected by compound C, but glutamate release was suggested to be controlled by AMPK. Our results suggest that activation of AMPK by TBT causes neuronal death through mediating glutamate release.

  20. Prion Protein Promotes Kidney Iron Uptake via Its Ferrireductase Activity*

    PubMed Central

    Haldar, Swati; Tripathi, Ajai; Qian, Juan; Beserra, Amber; Suda, Srinivas; McElwee, Matthew; Turner, Jerrold; Hopfer, Ulrich; Singh, Neena

    2015-01-01

    Brain iron-dyshomeostasis is an important cause of neurotoxicity in prion disorders, a group of neurodegenerative conditions associated with the conversion of prion protein (PrPC) from its normal conformation to an aggregated, PrP-scrapie (PrPSc) isoform. Alteration of iron homeostasis is believed to result from impaired function of PrPC in neuronal iron uptake via its ferrireductase activity. However, unequivocal evidence supporting the ferrireductase activity of PrPC is lacking. Kidney provides a relevant model for this evaluation because PrPC is expressed in the kidney, and ∼370 μg of iron are reabsorbed daily from the glomerular filtrate by kidney proximal tubule cells (PT), requiring ferrireductase activity. Here, we report that PrPC promotes the uptake of transferrin (Tf) and non-Tf-bound iron (NTBI) by the kidney in vivo and mainly NTBI by PT cells in vitro. Thus, uptake of 59Fe administered by gastric gavage, intravenously, or intraperitoneally was significantly lower in PrP-knock-out (PrP−/−) mouse kidney relative to PrP+/+ controls. Selective in vivo radiolabeling of plasma NTBI with 59Fe revealed similar results. Expression of exogenous PrPC in immortalized PT cells showed localization on the plasma membrane and intracellular vesicles and increased transepithelial transport of 59Fe-NTBI and to a smaller extent 59Fe-Tf from the apical to the basolateral domain. Notably, the ferrireductase-deficient mutant of PrP (PrPΔ51–89) lacked this activity. Furthermore, excess NTBI and hemin caused aggregation of PrPC to a detergent-insoluble form, limiting iron uptake. Together, these observations suggest that PrPC promotes retrieval of iron from the glomerular filtrate via its ferrireductase activity and modulates kidney iron metabolism. PMID:25572394

  1. Multifunctional antimicrobial proteins and peptides: natural activators of immune systems.

    PubMed

    Niyonsaba, François; Nagaoka, Isao; Ogawa, Hideoki; Okumura, Ko

    2009-01-01

    In addition to the physical barrier of the stratum corneum, cutaneous innate immunity also includes the release of various humoral mediators, such as cytokines and chemokines, recruitment and activation of phagocytes, and the production of antimicrobial proteins/peptides (AMPs). AMPs form an innate epithelial chemical shield, which provides a front-line component in innate immunity to inhibit microbial invasion; however, this might be an oversimplification of the diverse functions of these molecules. In fact, apart from exhibiting a broad spectrum of microbicidal properties, it is increasingly evident that AMPs display additional activities that are related to the stimulation and modulation of the cutaneous immune system. These diverse functions include chemoattraction and activation of immune and/or inflammatory cells, the production and release of cytokines and chemokines, acceleration of angiogenesis, promotion of wound healing, neutralization of harmful microbial products, and bridging of both innate and adaptive immunity. Thus, better understanding of the functions of AMPs in skin and identification of their signaling mechanisms may offer new strategies for the development of potential therapeutics for the treatment of infection- and/or inflammation-related skin diseases. Here, we briefly outline the structure, regulation of expression, and multifunctional roles of principal skin-derived AMPs.

  2. Allosteric activation of apicomplexan calcium-dependent protein kinases.

    PubMed

    Ingram, Jessica R; Knockenhauer, Kevin E; Markus, Benedikt M; Mandelbaum, Joseph; Ramek, Alexander; Shan, Yibing; Shaw, David E; Schwartz, Thomas U; Ploegh, Hidde L; Lourido, Sebastian

    2015-09-01

    Calcium-dependent protein kinases (CDPKs) comprise the major group of Ca2+-regulated kinases in plants and protists. It has long been assumed that CDPKs are activated, like other Ca2+-regulated kinases, by derepression of the kinase domain (KD). However, we found that removal of the autoinhibitory domain from Toxoplasma gondii CDPK1 is not sufficient for kinase activation. From a library of heavy chain-only antibody fragments (VHHs), we isolated an antibody (1B7) that binds TgCDPK1 in a conformation-dependent manner and potently inhibits it. We uncovered the molecular basis for this inhibition by solving the crystal structure of the complex and simulating, through molecular dynamics, the effects of 1B7-kinase interactions. In contrast to other Ca2+-regulated kinases, the regulatory domain of TgCDPK1 plays a dual role, inhibiting or activating the kinase in response to changes in Ca2+ concentrations. We propose that the regulatory domain of TgCDPK1 acts as a molecular splint to stabilize the otherwise inactive KD. This dependence on allosteric stabilization reveals a novel susceptibility in this important class of parasite enzymes.

  3. MDMX exerts its oncogenic activity via suppression of retinoblastoma protein.

    PubMed

    Zhang, H; Hu, L; Qiu, W; Deng, T; Zhang, Y; Bergholz, J; Xiao, Z-X

    2015-10-29

    Inactivation of the retinoblastoma protein (RB) has a major role in the development of human malignancies. We have previously shown that MDM2, an ubiquitin E3 ligase and major negative regulator of p53, binds to and promotes proteasome-mediated degradation of RB. MDMX, a homolog of MDM2, also binds to and inhibits p53 transactivation activity, yet it does not possess intrinsic ubiquitin ligase activity. Here, we show that MDMX binds to and promotes RB degradation in an MDM2-dependent manner. Specifically, the MDMX C-terminal ring domain binds to the RB C-pocket and enhances MDM2-RB interaction. Silencing MDMX induces RB accumulation, cell cycle arrest and senescence-like phenotypes, which are reverted by simultaneous RB knockdown. Furthermore, MDMX ablation leads to significant retardation of xenograft tumor growth, concomitant with RB accumulation. These results demonstrate that MDMX exerts oncogenic activity via suppression of RB, and suggest that both MDM2 and MDMX could be chemotherapeutic targets. PMID:25703327

  4. Mys protein regulates protein kinase A activity by interacting with regulatory type Ialpha subunit during vertebrate development.

    PubMed

    Kotani, Tomoya; Iemura, Shun-ichiro; Natsume, Tohru; Kawakami, Koichi; Yamashita, Masakane

    2010-02-12

    During embryonic development, protein kinase A (PKA) plays a key role in cell fate specification by antagonizing the Hedgehog (Hh) signaling pathway. However, the mechanism by which PKA activity is regulated remains unknown. Here we show that the Misty somites (Mys) protein regulates the level of PKA activity during embryonic development in zebrafish. We isolate PKA regulatory type Ialpha subunit (Prkar1a) as a protein interacting with Mys by pulldown assay in HEK293 cells followed by mass spectrometry analysis. We show an interaction between endogenous Mys and Prkar1a in the zebrafish embryo. Mys binds to Prkar1a in its C terminus region, termed PRB domain, and activates PKA in vitro. Conversely, knockdown of Mys in zebrafish embryos results in reduction in PKA activity. We also show that knockdown of Mys induces ectopic activation of Hh target genes in the eyes, neural tube, and somites downstream of Smoothened, a protein essential for transduction of Hh signaling activity. The altered patterning of gene expression is rescued by activation of PKA. Together, our results reveal a molecular mechanism of regulation of PKA activity that is dependent on a protein-protein interaction and demonstrate that PKA activity regulated by Mys is indispensable for negative regulation of the Hh signaling pathway in Hh-responsive cells. PMID:20018846

  5. Pharmacological inhibition of eicosanoids and platelet-activating factor signaling impairs zymosan-induced release of IL-23 by dendritic cells.

    PubMed

    Rodríguez, Mario; Márquez, Saioa; Montero, Olimpio; Alonso, Sara; Frade, Javier García; Crespo, Mariano Sánchez; Fernández, Nieves

    2016-02-15

    The engagement of the receptors for fungal patterns induces the expression of cytokines, the release of arachidonic acid, and the production of PGE2 in human dendritic cells (DC), but few data are available about other lipid mediators that may modulate DC function. The combined antagonism of leukotriene (LT) B4, cysteinyl-LT, and platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) inhibited IL23A mRNA expression in response to the fungal surrogate zymosan and to a lower extent TNFA (tumor necrosis factor-α) and CSF2 (granulocyte macrophage colony-stimulating factor) mRNA. The combination of lipid mediators and the lipid extract of zymosan-conditioned medium increased the induction of IL23A by LPS (bacterial lipopolysaccharide), thus suggesting that unlike LPS, zymosan elicits the production of mediators at a concentration enough for optimal response. Zymosan induced the release of LTB4, LTE4, 12-hydroxyeicosatetraenoic acid (12-HETE), and PAF C16:0. DC showed a high expression and detectable Ser663 phosphorylation of 5-lipoxygenase in response to zymosan, and a high expression and activity of LPCAT1/2 (lysophosphatidylcholine acyltransferase 1 and 2), the enzymes that incorporate acetate from acetyl-CoA into choline-containing lysophospholipids to produce PAF. Pharmacological modulation of the arachidonic acid cascade and the PAF receptor inhibited the binding of P-71Thr-ATF2 (activating transcription factor 2) to the IL23A promoter, thus mirroring their effects on the expression of IL23A mRNA and IL-23 protein. These results indicate that LTB4, cysteinyl-LT, and PAF, acting through their cognate G protein-coupled receptors, contribute to the phosphorylation of ATF2 and play a central role in IL23A promoter trans-activation and the cytokine signature induced by fungal patterns. PMID:26673542

  6. Pharmacological inhibition of eicosanoids and platelet-activating factor signaling impairs zymosan-induced release of IL-23 by dendritic cells.

    PubMed

    Rodríguez, Mario; Márquez, Saioa; Montero, Olimpio; Alonso, Sara; Frade, Javier García; Crespo, Mariano Sánchez; Fernández, Nieves

    2016-02-15

    The engagement of the receptors for fungal patterns induces the expression of cytokines, the release of arachidonic acid, and the production of PGE2 in human dendritic cells (DC), but few data are available about other lipid mediators that may modulate DC function. The combined antagonism of leukotriene (LT) B4, cysteinyl-LT, and platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) inhibited IL23A mRNA expression in response to the fungal surrogate zymosan and to a lower extent TNFA (tumor necrosis factor-α) and CSF2 (granulocyte macrophage colony-stimulating factor) mRNA. The combination of lipid mediators and the lipid extract of zymosan-conditioned medium increased the induction of IL23A by LPS (bacterial lipopolysaccharide), thus suggesting that unlike LPS, zymosan elicits the production of mediators at a concentration enough for optimal response. Zymosan induced the release of LTB4, LTE4, 12-hydroxyeicosatetraenoic acid (12-HETE), and PAF C16:0. DC showed a high expression and detectable Ser663 phosphorylation of 5-lipoxygenase in response to zymosan, and a high expression and activity of LPCAT1/2 (lysophosphatidylcholine acyltransferase 1 and 2), the enzymes that incorporate acetate from acetyl-CoA into choline-containing lysophospholipids to produce PAF. Pharmacological modulation of the arachidonic acid cascade and the PAF receptor inhibited the binding of P-71Thr-ATF2 (activating transcription factor 2) to the IL23A promoter, thus mirroring their effects on the expression of IL23A mRNA and IL-23 protein. These results indicate that LTB4, cysteinyl-LT, and PAF, acting through their cognate G protein-coupled receptors, contribute to the phosphorylation of ATF2 and play a central role in IL23A promoter trans-activation and the cytokine signature induced by fungal patterns.

  7. Antitussive and immunomodulating activities of instant coffee arabinogalactan-protein.

    PubMed

    Nosáľová, G; Prisenžňáková, L; Paulovičová, E; Capek, P; Matulová, M; Navarini, L; Liverani, F Suggi

    2011-11-01

    A low molecular mass arabinogalactan-protein (AGP) composed of galactose and arabinose with a low protein content, isolated from the instant coffee powder of Coffea arabica beans, has been tested on antitussive (in vivo) and immunomodulating (ex vivo) activities. The results of antitussive tests revealed a significant dose dependant cough-suppressive effect of coffee AGP. It was observed 30 or 60 min after AGP administration and its efficacy lasted during the entire experiment course. Immunological tests showed that AGP affected some mediators of immunocompetent cells of immune system as TNF-α, IFN-γ and IL-2 cytokines. It seems that coffee AGP is a good inductor of both pro-inflammatory cytokines TNF-α and IFN-γ, however, less potent in TNF-α induction in comparison with that of β-D-glucan. Evident induction of TNF-α, IL-2 and IFN-γ cytokines, pro-TH1 polarization supports our conclusion about bio-immunological efficacy of AGP with an emphasis on the cellular immunity.

  8. Functional characterization of alpha-synuclein protein with antimicrobial activity.

    PubMed

    Park, Seong-Cheol; Moon, Jeong Chan; Shin, Su Young; Son, Hyosuk; Jung, Young Jun; Kim, Nam-Hong; Kim, Young-Min; Jang, Mi-Kyeong; Lee, Jung Ro

    2016-09-16

    Alpha-synuclein (α-Syn), a small (14 kDa) protein associated with Parkinson's disease, is abundant in human neural tissues. α-Syn plays an important role in maintaining a supply of synaptic vesicles in presynaptic terminals; however, the mechanism by which it performs this function are not well understood. In addition, there is a correlation between α-Syn over-expression and upregulation of an innate immune response. Given the growing body of literature surrounding antimicrobial peptides (AMPs) in the brain, and the similarities between α-Syn and a previously characterized AMP, Amyloid-β, we set out to investigate if α-Syn shares AMP-like properties. Here we demonstrate that α-Syn exhibits antibacterial activity against Escherichia coli and Staphylococcus aureus. In addition, we demonstrate a role for α-Syn in inhibiting various pathogenic fungal strains such as Aspergillus flavus, Aspergillus fumigatus and Rhizoctonia solani. We also analyzed localizations of recombinant α-Syn protein in E. coli and Candida albicans. These results suggest that in addition to α-Syn's role in neurotransmitter release, it appears to be a natural AMP. PMID:27520375

  9. Ultra-sensitive fluorescent proteins for imaging neuronal activity

    PubMed Central

    Chen, Tsai-Wen; Wardill, Trevor J.; Sun, Yi; Pulver, Stefan R.; Renninger, Sabine L.; Baohan, Amy; Schreiter, Eric R.; Kerr, Rex A.; Orger, Michael B.; Jayaraman, Vivek; Looger, Loren L.; Svoboda, Karel; Kim, Douglas S.

    2013-01-01

    Summary Fluorescent calcium sensors are widely used to image neural activity. Using structure-based mutagenesis and neuron-based screening, we developed a family of ultra-sensitive protein calcium sensors (GCaMP6) that outperformed other sensors in cultured neurons and in zebrafish, flies, and mice in vivo. In layer 2/3 pyramidal neurons of the mouse visual cortex, GCaMP6 reliably detected single action potentials in neuronal somata and orientation-tuned synaptic calcium transients in individual dendritic spines. The orientation tuning of structurally persistent spines was largely stable over timescales of weeks. Orientation tuning averaged across spine populations predicted the tuning of their parent cell. Although the somata of GABAergic neurons showed little orientation tuning, their dendrites included highly tuned dendritic segments (5 - 40 micrometers long). GCaMP6 sensors thus provide new windows into the organization and dynamics of neural circuits over multiple spatial and temporal scales. PMID:23868258

  10. Xylazine Activates Adenosine Monophosphate-Activated Protein Kinase Pathway in the Central Nervous System of Rats.

    PubMed

    Shi, Xing-Xing; Yin, Bai-Shuang; Yang, Peng; Chen, Hao; Li, Xin; Su, Li-Xue; Fan, Hong-Gang; Wang, Hong-Bin

    2016-01-01

    Xylazine is a potent analgesic extensively used in veterinary and animal experimentation. Evidence exists that the analgesic effect can be inhibited using adenosine 5'-monophosphate activated protein kinase (AMPK) inhibitors. Considering this idea, the aim of this study was to investigate whether the AMPK signaling pathway is involved in the central analgesic mechanism of xylazine in the rat. Xylazine was administrated via the intraperitoneal route. Sprague-Dawley rats were sacrificed and the cerebral cortex, cerebellum, hippocampus, thalamus and brainstem were collected for determination of liver kinase B1 (LKB1) and AMPKα mRNA expression using quantitative real-time polymerase chain reaction (qPCR), and phosphorylated LKB1 and AMPKα levels using western blot. The results of our study showed that compared with the control group, xylazine induced significant increases in AMPK activity in the cerebral cortex, hippocampus, thalamus and cerebellum after rats received xylazine (P < 0.01). Increased AMPK activities were accompanied with increased phosphorylation levels of LKB1 in corresponding regions of rats. The protein levels of phosphorylated LKB1 and AMPKα in these regions returned or tended to return to control group levels. However, in the brainstem, phosphorylated LKB1 and AMPKα protein levels were decreased by xylazine compared with the control (P < 0.05). In conclusion, our data indicates that xylazine alters the activities of LKB1 and AMPK in the central nervous system of rats, which suggests that xylazine affects the regulatory signaling pathway of the analgesic mechanism in the rat brain. PMID:27049320

  11. Engineering Fluorogen Activating Proteins into Self-Assembling Materials

    PubMed Central

    Saunders, Matthew J.; Liu, Wen; Szent-Gyorgyi, Christopher; Wen, Yi; Drennen, Zachary; Waggoner, Alan S.; Meng, Wilson S.

    2013-01-01

    We present herein characteristics of a conjugate in which dL5, a fluorogen-activating protein (FAP) and AEAEAKAK, an amphiphilic peptide are combined to form a solid-phase fluorescence-detection platform. The FAP dL5 is a covalently linked dimer of two identical light chain variable fragments which activates the fluorescence of the fluorogen malachite green (MG). The amphiphilic peptide of sequence AEAEAKAK is a building block of stimuli-responsive materials that undergoes sol-gel phase transition at high ionic strengths. We hypothesize that the novel bi-functional protein containing both the FAP and the amphiphile, termed dL5_EAK, co-assembles with the self-assembling peptide [AEAEAKAK]2 (EAK16-II) to form an insoluble membrane composite whereby the fluorescence enhancement function of the FAP domain remains intact. Denaturing polyacrylamide electrophoresis indicated that greater than 78% of dL5_EAK incorporates into the EAK16-II membrane. Conversely, less than 32% of dL5 without the EAK sequence associates with the insoluble fraction of EAK16-II in buffers. Membranes containing dL5_EAK and EAK16-II exhibited at least 4-fold higher fluorescence intensity compared to mixtures containing dL5 and EAK16-II. Scanning electron microscopy revealed the presence of particulates, presumably FAPs, scattering on the membrane fibrils. The evidence suggests a system of materials that can be developed into in situ-forming local sensors by immobilizing dL5 into coacervate, on which MG can be detected. It is envisioned that dL5 membranes can be established in diseased locales to monitor infiltration and migration of inflammatory cells marked with antibodies conjugated to MG. PMID:23573960

  12. Testicular hyperthermia induces Unfolded Protein Response signaling activation in spermatocyte.

    PubMed

    Kim, Jung-Hak; Park, Sun-Ji; Kim, Tae-Shin; Park, Hyo-Jin; Park, Junghyung; Kim, Bo Kyung; Kim, Gyeong-Ryul; Kim, Jin-Man; Huang, Song Mei; Chae, Jung-Il; Park, Choon-Keun; Lee, Dong-Seok

    2013-05-17

    The testes of most mammals are sensitive to temperature. To survive and adapt under conditions that promote endoplasmic reticulum (ER) stress such as heat shock, cells have a self-protective mechanism against ER stress that has been termed the "Unfolded Protein Response" (UPR). However, the cellular and molecular events underlying spermatogenesis with testicular hyperthermia involved in the UPR signaling pathway under ER stress remain poorly understood. In the present study, we verified that UPR signaling via phospho-eIF2α/ATF4/GADD34, p90ATF6, and phospho-IRE1α/XBP-1 is activated with testicular hyperthermia (43 °C, 15 min/day) and induced ER stress-mediated apoptosis associated with CHOP, phospho-JNK, and caspase-3 after repetitive periods of hyperthermia. Levels of phospho-eIF2α protein of mouse spermatocytes in the testis were rapidly increased by one cycle of testicular hyperthermia. ATF4/GADD34 and p90ATF6 expression gradually increased and decreased, respectively, with repetitive cycles of hyperthermia. Spliced XBP1 mRNA as a marker of IRE1 activity was increased after one, three cycles of hyperthermia and decreased by five cycles of hyperthermia. Although the levels of anti-apoptotic phospho-JNK (p54) were gradually decreased after three cycles of hyperthermia, CHOP expression was rapidly increased. After five cycles of testicular hyperthermia, the levels of cleaved caspase-3 and TUNEL-positive apoptotic spermatocytes cells were significantly increased. Our data demonstrated that testicular hyperthermia induces UPR signaling and repetitive cycles of hyperthermia lead to apoptosis of spermatocytes in mouse testis. These results suggest a link between the UPR signaling pathway and testicular hyperthermia.

  13. Pranlukast inhibits renal epithelial cyst progression via activation of AMP-activated protein kinase.

    PubMed

    Pathomthongtaweechai, Nutthapoom; Soodvilai, Sunhapas; Chatsudthipong, Varanuj; Muanprasat, Chatchai

    2014-02-01

    Cysteinyl leukotriene receptor 1 (CysLT1 receptor) antagonists were found to inhibit chloride secretion in human airway epithelial cells. Since chloride secretion in renal epithelial cells, which shares common mechanisms with airway epithelial cells, plays important roles in renal cyst progression in polycystic kidney disease (PKD), this study was aimed to investigate effects of drugs acting as CysLT1 receptor antagonists on renal cyst progression and its underlying mechanisms. Effects of CysLT1 receptor antagonists on renal cyst growth and formation were determined using Madine Darby canine kidney (MDCK) cyst models. Mechanisms of actions of CysLT1 receptor antagonists were determined using short-circuit current measurement, assays of cell viability and cell proliferation, and immunoblot analysis of signaling proteins. Of the three drugs acting as CysLT1 receptor antagonists (montelukast, pranlukast and zafirlukast) tested, pranlukast was the most promising drug that inhibited MDCK cyst growth and formation without affecting cell viability. Its effect was independent of the inhibition of CysLT1 receptors. Instead, it reduced cAMP-activated chloride secretion and proliferation of MDCK cells in an AMP-activated protein kinase (AMPK)-dependent manner and had no effect on CFTR protein expression. Interestingly, pranlukast enhanced AMPK activation via calcium/calmodulin-dependent protein kinase kinase beta (CaMKKβ) with consequent activation of acetyl-CoA carboxylase (ACC) and suppression of mammalian target of rapamycin (mTOR) pathway. These results indicate that pranlukast retards renal epithelial cyst progression by inhibiting cAMP-activated chloride secretion and cell proliferation via CaMKKβ-AMPK-mTOR pathway. Therefore, pranlukast represents a class of known drugs that may have potential utility in PKD treatment. PMID:24360935

  14. Latent Ice Recrystallization Inhibition Activity in Nonantifreeze Proteins: Ca2+-Activated Plant Lectins and Cation-Activated Antimicrobial Peptides

    PubMed Central

    2015-01-01

    Organisms living in polar regions have evolved a series of antifreeze (glyco) proteins (AFGPs) to enable them to survive by modulating the structure of ice. These proteins have huge potential for use in cellular cryopreservation, ice-resistant surfaces, frozen food, and cryosurgery, but they are limited by their relatively low availability and questions regarding their mode of action. This has triggered the search for biomimetic materials capable of reproducing this function. The identification of new structures and sequences capable of inhibiting ice growth is crucial to aid our understanding of these proteins. Here, we show that plant c-type lectins, which have similar biological function to human c-type lectins (glycan recognition) but no sequence homology to AFPs, display calcium-dependent ice recrystallization inhibition (IRI) activity. This IRI activity can be switched on/off by changing the Ca2+ concentration. To show that more (nonantifreeze) proteins may exist with the potential to display IRI, a second motif was considered, amphipathicity. All known AFPs have defined hydrophobic/hydrophilic domains, rationalizing this choice. The cheap, and widely used, antimicrobial Nisin was found to have cation-dependent IRI activity, controlled by either acid or addition of histidine-binding ions such as zinc or nickel, which promote its amphipathic structure. These results demonstrate a new approach in the identification of antifreeze protein mimetic macromolecules and may help in the development of synthetic mimics of AFPs. PMID:26407233

  15. Latent Ice Recrystallization Inhibition Activity in Nonantifreeze Proteins: Ca2+-Activated Plant Lectins and Cation-Activated Antimicrobial Peptides.

    PubMed

    Mitchell, Daniel E; Gibson, Matthew I

    2015-10-12

    Organisms living in polar regions have evolved a series of antifreeze (glyco) proteins (AFGPs) to enable them to survive by modulating the structure of ice. These proteins have huge potential for use in cellular cryopreservation, ice-resistant surfaces, frozen food, and cryosurgery, but they are limited by their relatively low availability and questions regarding their mode of action. This has triggered the search for biomimetic materials capable of reproducing this function. The identification of new structures and sequences capable of inhibiting ice growth is crucial to aid our understanding of these proteins. Here, we show that plant c-type lectins, which have similar biological function to human c-type lectins (glycan recognition) but no sequence homology to AFPs, display calcium-dependent ice recrystallization inhibition (IRI) activity. This IRI activity can be switched on/off by changing the Ca2+ concentration. To show that more (nonantifreeze) proteins may exist with the potential to display IRI, a second motif was considered, amphipathicity. All known AFPs have defined hydrophobic/hydrophilic domains, rationalizing this choice. The cheap, and widely used, antimicrobial Nisin was found to have cation-dependent IRI activity, controlled by either acid or addition of histidine-binding ions such as zinc or nickel, which promote its amphipathic structure. These results demonstrate a new approach in the identification of antifreeze protein mimetic macromolecules and may help in the development of synthetic mimics of AFPs. PMID:26407233

  16. Latent Ice Recrystallization Inhibition Activity in Nonantifreeze Proteins: Ca2+-Activated Plant Lectins and Cation-Activated Antimicrobial Peptides.

    PubMed

    Mitchell, Daniel E; Gibson, Matthew I

    2015-10-12

    Organisms living in polar regions have evolved a series of antifreeze (glyco) proteins (AFGPs) to enable them to survive by modulating the structure of ice. These proteins have huge potential for use in cellular cryopreservation, ice-resistant surfaces, frozen food, and cryosurgery, but they are limited by their relatively low availability and questions regarding their mode of action. This has triggered the search for biomimetic materials capable of reproducing this function. The identification of new structures and sequences capable of inhibiting ice growth is crucial to aid our understanding of these proteins. Here, we show that plant c-type lectins, which have similar biological function to human c-type lectins (glycan recognition) but no sequence homology to AFPs, display calcium-dependent ice recrystallization inhibition (IRI) activity. This IRI activity can be switched on/off by changing the Ca2+ concentration. To show that more (nonantifreeze) proteins may exist with the potential to display IRI, a second motif was considered, amphipathicity. All known AFPs have defined hydrophobic/hydrophilic domains, rationalizing this choice. The cheap, and widely used, antimicrobial Nisin was found to have cation-dependent IRI activity, controlled by either acid or addition of histidine-binding ions such as zinc or nickel, which promote its amphipathic structure. These results demonstrate a new approach in the identification of antifreeze protein mimetic macromolecules and may help in the development of synthetic mimics of AFPs.

  17. Inducement of mitogen-activated protein kinases in frozen shoulders

    PubMed Central

    Kanbe, Katsuaki; Inoue, Kazuhiko; Inoue, Yasuo; Chen, Qian

    2010-01-01

    Background Mitogen-activated protein (MAP) kinases are well-known molecules that play key roles in mechanical stress signals during skeletal development. To test our hypothesis that the synovium in frozen shoulders is induced by MAP kinases, immunohistochemical analyses for detecting expression and signal transduction of MAP kinases were performed in synovial tissue obtained from the rotator interval (RI) in frozen shoulders. Methods Synovial tissues were examined from 10 frozen shoulder patients with a mean age of 55.4 years (46–62 years). Synovial tissues between the long head of the biceps tendon (LHB) and the RI in frozen shoulders were stained with hematoxylin and eosin (H&E) and then examined with immunohistochemical staining. Extracellular signal-regulated (ERK), the Jun N-terminal (JNK), and p38 mitogen-activated protein (MAP) kinases, nuclear factor κB (NF-κB), p50, CD29 (β1-integrin), matrix metalloproteinase (MMP)-3, interleukin-6 (IL-6), CD56, CD68, S-100, and vascular endothelial growth factor (VEGF) were analyzed to detect expression patterns. Results H&E showed vascular proliferation with fibrin and fibrous tissue in the synovium of frozen shoulders. ERK was expressed in the epithelial cells of vascular tissue, and JNK was expressed strongly in the interstitial cells around vascular tissue; p38 MAPK was not expressed. NF-κB was expressed in vascular tissue, and IL-6 was expressed around vascular tissue. CD29 (β1-integrin) was expressed in vascular tissue and in superficial cells of synovial tissue. MMP-3 and VEGF were expressed on the surface layer of synovial tissue and vascular tissue, and CD68 was expressed on the surface layer. Nerve-related proteins, CD56 and S-100, were expressed weakly. Conclusions Mechanical stress on the LHB and RI in the shoulder may induce ERK and JNK to express NF-κB by CD29 to develop capsule contracture, producing MMP-3, IL-6, and VEGF. PMID:19214689

  18. A sensitive and facile assay for the measurement of activated protein C activity levels in vivo.

    PubMed

    Orthner, C L; Kolen, B; Drohan, W N

    1993-05-01

    Activated protein C (APC) is a serine protease which plays an important role as a naturally occurring antithrombotic enzyme. APC, which is formed by thrombin-catalyzed limited proteolysis of the zymogen protein C, functions as an anticoagulant by proteolytic inactivation of the coagulation cofactors VIIIa and Va: APC is inhibited by several members of the serpin family as well a by alpha 2-macroglobulin. APC is being developed as a therapeutic for the prevention and treatment of thrombosis. We have developed an assay to quantify circulating levels of enzymatically active APC during its administration to patients, in healthy individuals, and in various disease states. This assay utilizes an EDTA-dependent anti-protein C monoclonal antibody (Mab) 7D7B10 to capture both APC and protein C from plasma, prepared from blood collected in an anticoagulant supplemented with the reversible inhibitor p-aminobenzamidine. Mab 7D7B10-derivatized agarose beads are added to the wells of a 96-well filtration plate, equilibrated with Tris-buffered saline, and incubated for 10 min with 200 microliters of plasma. After washing, APC and protein C are eluted from the immunosorbent beads with a calcium-containing buffer into the wells of a 96-well microtiter plate containing antithrombin III (ATIII) and heparin. The amidolytic activity of APC is then measured on a kinetic plate reader following the addition of L-pyroglutamyl-L-prolyl-L-arginine-p-nitroanilide (S-2366) substrate. The rate of substrate hydrolysis was proportional to APC concentration over a 200-fold concentration range (5.0 to 1,000 ng/ml) when measured continuously over a 15 to 30 min time period.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Protein Inhibitors of Activated STAT (Pias1 and Piasy) Differentially Regulate Pituitary Homeobox 2 (PITX2) Transcriptional Activity*

    PubMed Central

    Wang, Jianbo; Sun, Zhao; Zhang, Zichao; Saadi, Irfan; Wang, Jun; Li, Xiao; Gao, Shan; Engle, Jamison J.; Kuburas, Adisa; Fu, Xueyao; Yu, Wenjie; Klein, William H.; Russo, Andrew F.; Amendt, Brad A.

    2013-01-01

    Protein inhibitors of activated STAT (Pias) proteins can act independent of sumoylation to modulate the activity of transcription factors and Pias proteins interacting with transcription factors can either activate or repress their activity. Pias proteins are expressed in many tissues and cells during development and we asked if Pias proteins regulated the pituitary homeobox 2 (PITX2) homeodomain protein, which modulates developmental gene expression. Piasy and Pias1 proteins are expressed during craniofacial/tooth development and directly interact and differentially regulate PITX2 transcriptional activity. Piasy and Pias1 are co-expressed in craniofacial tissues with PITX2. Yeast two-hybrid, co-immunoprecipitation and pulldown experiments demonstrate Piasy and Pias1 interactions with the PITX2 protein. Piasy interacts with the PITX2 C-terminal tail to attenuate its transcriptional activity. In contrast, Pias1 interacts with the PITX2 C-terminal tail to increase PITX2 transcriptional activity. The E3 ligase activity associated with the RING domain in Piasy is not required for the attenuation of PITX2 activity, however, the RING domain of Pias1 is required for enhanced PITX2 transcriptional activity. Bimolecular fluorescence complementation assays reveal PITX2 interactions with Piasy and Pias1 in the nucleus. Piasy represses the synergistic activation of PITX2 with interacting co-factors and Piasy represses Pias1 activation of PITX2 transcriptional activity. In contrast, Pias1 did not affect the synergistic interaction of PITX2 with transcriptional co-factors. Last, we demonstrate that Pias proteins form a complex with PITX2 and Lef-1, and PITX2 and β-catenin. Lef-1, β-catenin, and Pias interactions with PITX2 provide new molecular mechanisms for the regulation of PITX2 transcriptional activity and the activity of Pias proteins. PMID:23515314

  20. Site-specific incorporation of redox active amino acids into proteins

    DOEpatents

    Alfonta, Lital; Schultz, Peter G.; Zhang, Zhiwen

    2009-02-24

    Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate redox active amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with redox active amino acids using these orthogonal pairs.

  1. Site-specific incorporation of redox active amino acids into proteins

    DOEpatents

    Alfonta; Lital , Schultz; Peter G. , Zhang; Zhiwen

    2010-10-12

    Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate redox active amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with redox active amino acids using these orthogonal pairs.

  2. Site-specific incorporation of redox active amino acids into proteins

    SciTech Connect

    Alfonta, Lital; Schultz, Peter G.; Zhang, Zhiwen

    2012-02-14

    Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate redox active amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with redox active amino acids using these orthogonal pairs.

  3. Site-specific incorporation of redox active amino acids into proteins

    SciTech Connect

    Alfonta, Lital; Schultz, Peter G.; Zhang, Zhiwen

    2011-08-30

    Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate redox active amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with redox active amino acids using these orthogonal pairs.

  4. Calcium-Oxidant Signaling Network Regulates AMP-activated Protein Kinase (AMPK) Activation upon Matrix Deprivation*

    PubMed Central

    Sundararaman, Ananthalakshmy; Amirtham, Usha; Rangarajan, Annapoorni

    2016-01-01

    The AMP-activated protein kinase (AMPK) has recently been implicated in anoikis resistance. However, the molecular mechanisms that activate AMPK upon matrix detachment remain unexplored. In this study, we show that AMPK activation is a rapid and sustained phenomenon upon matrix deprivation, whereas re-attachment to the matrix leads to its dephosphorylation and inactivation. Because matrix detachment leads to loss of integrin signaling, we investigated whether integrin signaling negatively regulates AMPK activation. However, modulation of focal adhesion kinase or Src, the major downstream components of integrin signaling, failed to cause a corresponding change in AMPK signaling. Further investigations revealed that the upstream AMPK kinases liver kinase B1 (LKB1) and Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ) contribute to AMPK activation upon detachment. In LKB1-deficient cells, we found AMPK activation to be predominantly dependent on CaMKKβ. We observed no change in ATP levels under detached conditions at early time points suggesting that rapid AMPK activation upon detachment was not triggered by energy stress. We demonstrate that matrix deprivation leads to a spike in intracellular calcium as well as oxidant signaling, and both these intracellular messengers contribute to rapid AMPK activation upon detachment. We further show that endoplasmic reticulum calcium release-induced store-operated calcium entry contributes to intracellular calcium increase, leading to reactive oxygen species production, and AMPK activation. We additionally show that the LKB1/CaMKK-AMPK axis and intracellular calcium levels play a critical role in anchorage-independent cancer sphere formation. Thus, the Ca2+/reactive oxygen species-triggered LKB1/CaMKK-AMPK signaling cascade may provide a quick, adaptable switch to promote survival of metastasizing cancer cells. PMID:27226623

  5. Activity of mitogen-activated protein kinases in the esophageal epithelium of patients with Barrett's esophagus.

    PubMed

    Chwiesko, A; Baniukiewicz, A; Semeniuk, J; Kaczmarski, M; Wasielica-Berger, J; Milewski, R; Dabrowski, A

    2015-01-01

    Barrett's esophagus (BE), a complication of gastroesophageal reflux disease, is associated with an increased risk of esophageal cancer. Mitogen-activated protein kinases may play an important role in the pathogenesis of this process. We aimed to evaluate mitogen-activated protein kinases activity in esophageal mucosa of patients with BE and find possible relationship between reflux type and BE. Twenty-four patients (mean age: 59 years) with gastroesophageal reflux disease symptoms and endoscopically suspected esophageal metaplasia (ESEM) were prospectively enrolled for testing by a multichannel intraluminal impedance monitoring along with a Bilitec 2000. Endoscopic biopsies were taken from methylene blue-positive pit patterns (sites suggesting specialized intestinal metaplasia [SIM]), from 2 cm above the Z-line and from cardial parts of the stomach. The biopsies were analyzed for extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 activity by Western blot. Seventeen ESEMs had histologically proven metaplasia: eight patients had SIM and nine had gastric-type epithelia (GE). Biliary reflux was more evident in SIM (P = 0.019) but not in GE (P = 0.019); non-biliary reflux was typical for GE (P = 0.005) but not for SIM (P = 0.04). Strong activations of ERK and p38 were found predominantly in SIM, but not in normal esophageal mucosa (NE) (P = 0.01 and P < 0.001 respectively). Strong signals for active JNK and p38 were detected in GE, but not in NE (P = 0.006 and P = 0.02 respectively). ERK activity was significantly higher than p38 activity in ESEM patients only with GE (P = 0.02). The strong activation of ERK, but not JNK is indicative of SIM. The presence of bile in gastroesophageal refluxate is predisposing to SIM, but not to GE in esophageal mucosa.

  6. Nitric oxide stress and activation of AMP-activated protein kinase impair β-cell sarcoendoplasmic reticulum calcium ATPase 2b activity and protein stability

    PubMed Central

    Tong, X; Kono, T; Evans-Molina, C

    2015-01-01

    The sarcoendoplasmic reticulum Ca2+ ATPase 2b (SERCA2b) pump maintains a steep Ca2+ concentration gradient between the cytosol and ER lumen in the pancreatic β-cell, and the integrity of this gradient has a central role in regulated insulin production and secretion, maintenance of ER function and β-cell survival. We have previously demonstrated loss of β-cell SERCA2b expression under diabetic conditions. To define the mechanisms underlying this, INS-1 cells and rat islets were treated with the proinflammatory cytokine interleukin-1β (IL-1β) combined with or without cycloheximide or actinomycin D. IL-1β treatment led to increased inducible nitric oxide synthase (iNOS) gene and protein expression, which occurred concurrently with the activation of AMP-activated protein kinase (AMPK). IL-1β led to decreased SERCA2b mRNA and protein expression, whereas time-course experiments revealed a reduction in protein half-life with no change in mRNA stability. Moreover, SERCA2b protein but not mRNA levels were rescued by treatment with the NOS inhibitor l-NMMA (NG-monomethyl l-arginine), whereas the NO donor SNAP (S-nitroso-N-acetyl-d,l-penicillamine) and the AMPK activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide) recapitulated the effects of IL-1β on SERCA2b protein stability. Similarly, IL-1β-induced reductions in SERCA2b expression were rescued by pharmacological inhibition of AMPK with compound C or by transduction of a dominant-negative form of AMPK, whereas β-cell death was prevented in parallel. Finally, to determine a functional relationship between NO and AMPK signaling and SERCA2b activity, fura-2/AM (fura-2-acetoxymethylester) Ca2+ imaging experiments were performed in INS-1 cells. Consistent with observed changes in SERCA2b expression, IL-1β, SNAP and AICAR increased cytosolic Ca2+ and decreased ER Ca2+ levels, suggesting congruent modulation of SERCA activity under these conditions. In aggregate, these results show that SERCA2b protein

  7. Mitogen-Activated Protein Kinases and Hypoxic/Ischemic Nephropathy.

    PubMed

    Luo, Fengbao; Shi, Jian; Shi, Qianqian; Xu, Xianlin; Xia, Ying; He, Xiaozhou

    2016-01-01

    Tissue hypoxia/ischemia is a pathological feature of many human disorders including stroke, myocardial infarction, hypoxic/ischemic nephropathy, as well as cancer. In the kidney, the combination of limited oxygen supply to the tissues and high oxygen demand is considered the main reason for the susceptibility of the kidney to hypoxic/ischemic injury. In recent years, increasing evidence has indicated that a reduction in renal oxygen tension/blood supply plays an important role in acute kidney injury, chronic kidney disease, and renal tumorigenesis. However, the underlying signaling mechanisms, whereby hypoxia alters cellular behaviors, remain poorly understood. Mitogen-activated protein kinases (MAPKs) are key signal-transducing enzymes activated by a wide range of extracellular stimuli, including hypoxia/ischemia. There are four major family members of MAPKs: the extracellular signal-regulated kinases-1 and -2 (ERK1/2), the c-Jun N-terminal kinases (JNK), p38 MAPKs, and extracellular signal-regulated kinase-5 (ERK5/BMK1). Recent studies, including ours, suggest that these MAPKs are differentially involved in renal responses to hypoxic/ischemic stress. This review will discuss their changes in hypoxic/ischemic pathophysiology with acute kidney injury, chronic kidney diseases and renal carcinoma. PMID:27544204

  8. Amyloid precursor protein controls cholesterol turnover needed for neuronal activity

    PubMed Central

    Pierrot, Nathalie; Tyteca, Donatienne; D'auria, Ludovic; Dewachter, Ilse; Gailly, Philippe; Hendrickx, Aurélie; Tasiaux, Bernadette; Haylani, Laetitia El; Muls, Nathalie; N'Kuli, Francisca; Laquerrière, Annie; Demoulin, Jean-Baptiste; Campion, Dominique; Brion, Jean-Pierre; Courtoy, Pierre J; Kienlen-Campard, Pascal; Octave, Jean-Noël

    2013-01-01

    Perturbation of lipid metabolism favours progression of Alzheimer disease, in which processing of Amyloid Precursor Protein (APP) has important implications. APP cleavage is tightly regulated by cholesterol and APP fragments regulate lipid homeostasis. Here, we investigated whether up or down regulation of full-length APP expression affected neuronal lipid metabolism. Expression of APP decreased HMG-CoA reductase (HMGCR)-mediated cholesterol biosynthesis and SREBP mRNA levels, while its down regulation had opposite effects. APP and SREBP1 co-immunoprecipitated and co-localized in the Golgi. This interaction prevented Site-2 protease-mediated processing of SREBP1, leading to inhibition of transcription of its target genes. A GXXXG motif in APP sequence was critical for regulation of HMGCR expression. In astrocytes, APP and SREBP1 did not interact nor did APP affect cholesterol biosynthesis. Neuronal expression of APP decreased both HMGCR and cholesterol 24-hydroxylase mRNA levels and consequently cholesterol turnover, leading to inhibition of neuronal activity, which was rescued by geranylgeraniol, generated in the mevalonate pathway, in both APP expressing and mevastatin treated neurons. We conclude that APP controls cholesterol turnover needed for neuronal activity. PMID:23554170

  9. Druggability analysis and classification of protein tyrosine phosphatase active sites

    PubMed Central

    Ghattas, Mohammad A; Raslan, Noor; Sadeq, Asil; Al Sorkhy, Mohammad; Atatreh, Noor

    2016-01-01

    Protein tyrosine phosphatases (PTP) play important roles in the pathogenesis of many diseases. The fact that no PTP inhibitors have reached the market so far has raised many questions about their druggability. In this study, the active sites of 17 PTPs were characterized and assessed for its ability to bind drug-like molecules. Consequently, PTPs were classified according to their druggability scores into four main categories. Only four members showed intermediate to very druggable pocket; interestingly, the rest of them exhibited poor druggability. Particularly focusing on PTP1B, we also demonstrated the influence of several factors on the druggability of PTP active site. For instance, the open conformation showed better druggability than the closed conformation, while the tight-bound water molecules appeared to have minimal effect on the PTP1B druggability. Finally, the allosteric site of PTP1B was found to exhibit superior druggability compared to the catalytic pocket. This analysis can prove useful in the discovery of new PTP inhibitors by assisting researchers in predicting hit rates from high throughput or virtual screening and saving unnecessary cost, time, and efforts via prioritizing PTP targets according to their predicted druggability. PMID:27757011

  10. Total protein, animal protein, and physical activity in relation to muscle mass in middle-aged and older Americans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resistance training is recognized as a good strategy for retarding age-related declines in muscle mass and strength. Recent studies have also highlighted the potential value of protein intakes in excess of current recommendations. The roles that leisure-time physical activity and protein quality mig...

  11. Characterization of murine BATF: a negative regulator of activator protein-1 activity in the thymus.

    PubMed

    Williams, K L; Nanda, I; Lyons, G E; Kuo, C T; Schmid, M; Leiden, J M; Kaplan, M H; Taparowsky, E J

    2001-05-01

    BATF belongs to the AP-1/ATF superfamily of transcription factors and forms heterodimers with Jun proteins to bind AP-1 consensus DNA. Unlike Fos/Jun heterodimers which stimulate gene transcription, BATF/Jun heterodimers are transcriptionally inert and inhibit biological processes that are associated with the overstimulation of AP-1 activity. Here, we describe the murine BATF cDNA and genomic clones and map the BATF locus to chromosome 12 D2-3. Using in situ hybridization of BATF mRNA, we show that BATF gene expression is highly restricted, with the most prominent signals detected in the thymus. BATF mRNA levels are regulated differentially during discrete stages of T cell development and are up-regulated following activation of T cells in the periphery. To demonstrate the impact of BATF on AP-1 activity in vivo, AP-1 luciferase reporter mice were crossed to transgenic mice overexpressing BATF exclusively in thymic T cells. Results show that elevated levels of BATF protein correlate with reduced transactivation by AP-1. Since the differential regulation of AP-1 activity is linked to key transitions in the developing immune system, our observations support a critical role for BATF in determining the overall level of AP-1 activity, and thus AP-1 target gene expression, in specific T cell subtypes.

  12. Nature's "silver bullet" for anticoagulation: mechanism of Zymogen Protein C to Activated Protein C.

    PubMed

    Bruley, Duane F; Streiff, Michael B

    2013-01-01

    We have defined the Zymogen Protein C (ZPC) to Activated Protein C (APC) process as the "silver bullet" of blood anticoagulation. This definition suggests that the anticoagulation activity occurs when and where it is needed, resulting in local anticoagulation without enhanced bleeding. It is important for man to be able to manufacture an inexpensive ZPC product or to find a substitute drug to duplicate one of God's natural anticoagulant/antithrombotic processes, in vivo, in human blood. After intense research and at great expense scientists have not been able to produce a safe anticoagulant. All products that are now being used can cause bleeding even if dosing is carefully monitored. In fact many professionals in the health care and the pharmaceutical industries define an anticoagulant as a drug that "does" cause bleeding. This results in a large financial burden that has been placed on the health care industry because of necessary emergency treatments for dangerous occurrences. In addition, many patients are dying annually due to internal and external bleeds created or enhanced by presently administered anticoagulants. Since there are no safe drugs available it is necessary to use the existing products when a medical condition calls for an anticoagulant. This paper will discuss the ZPC process and why its mechanistic design is one of nature's unique defenses against unwanted blood clotting. The prevention and lysis of clots allows normal blood flow and therefore results in the required tissue oxygenation for cell function and survival. If clinical research is carried out with great care it could uncover other uses of ZPC that will allow safer medical procedures, in addition to its use with standard PC deficiency cases. An important example might be for some brain surgeries where the use of existing anticoagulants is unsafe because of potential bleeds. Clinical research could reveal an efficacious ZPC level (for instance, 125, 150, or 200% of normal) that would

  13. Activation of multiple mitogen-activated protein kinases by recombinant calcitonin gene-related peptide receptor.

    PubMed

    Parameswaran, N; Disa, J; Spielman, W S; Brooks, D P; Nambi, P; Aiyar, N

    2000-02-18

    Calcitonin gene-related peptide is a 37-amino-acid neuropeptide and a potent vasodilator. Although calcitonin gene-related peptide has been shown to have a number of effects in a variety of systems, the mechanisms of action and the intracellular signaling pathways, especially the regulation of mitogen-activated protien kinase (MAPK) pathway, is not known. In the present study we investigated the role of calcitonin gene-related peptide in the regulation of MAPKs in human embryonic kidney (HEK) 293 cells stably transfected with a recombinant porcine calcitonin gene-related peptide-1 receptor. Calcitonin gene-related peptide caused a significant dose-dependent increase in cAMP response and the effect was inhibited by calcitonin gene-related peptide(8-37), the calcitonin gene-related peptide-receptor antagonist. Calcitonin gene-related peptide also caused a time- and concentration-dependent increase in extracellular signal-regulated kinase (ERK) and P38 mitogen-activated protein kinase (P38 MAPK) activities, with apparently no significant change in cjun-N-terminal kinase (JNK) activity. Forskolin, a direct activator of adenylyl cyclase also stimulated ERK and P38 activities in these cells suggesting the invovement of cAMP in this process. Calcitonin gene-related peptide-stimulated ERK and P38 MAPK activities were inhibited significantly by calcitonin gene-related peptide receptor antagonist, calcitonin gene-related peptide-(8-37) suggesting the involvement of calcitonin gene-related peptide-1 receptor. Preincubation of the cells with the cAMP-dependent protein kinase inhibitor, H89 [¿N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide, hydrochloride¿] inhibited calcitonin gene-related peptide-mediated activation of ERK and p38 kinases. On the other hand, preincubation of the cells with wortmannin ¿[1S-(1alpha,6balpha,9abeta,11alpha, 11bbeta)]-11-(acetyloxy)-1,6b,7,8,9a,10,11, 11b-octahydro-1-(methoxymethyl)-9a,11b-dimethyl-3H-furo[4,3, 2-de]indeno[4,5-h]-2

  14. Antioxidant activity of black bean (Phaseolus vulgaris L.) protein hydrolysates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this work was to study the effect of enzymatic hydrolysis of black bean protein concentrate using different enzymes. Bean proteins were extracted and hydrolyzed over a period of 120 min using the enzymes pepsin or alcalase. The protein hydrolysates’ molecular weight was assayed by e...

  15. Juvenile hormone-activated phospholipase C pathway enhances transcriptional activation by the methoprene-tolerant protein

    PubMed Central

    Liu, Pengcheng; Peng, Hong-Juan; Zhu, Jinsong

    2015-01-01

    Juvenile hormone (JH) is a key regulator of a wide diversity of developmental and physiological events in insects. Although the intracellular JH receptor methoprene-tolerant protein (MET) functions in the nucleus as a transcriptional activator for specific JH-regulated genes, some JH responses are mediated by signaling pathways that are initiated by proteins associated with plasma membrane. It is unknown whether the JH-regulated gene expression depends on the membrane-mediated signal transduction. In Aedes aegypti mosquitoes, we found that JH activated the phospholipase C (PLC) pathway and quickly increased the levels of inositol 1,4,5-trisphosphate, diacylglycerol, and intracellular calcium, leading to activation and autophosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII). When abdomens from newly emerged mosquitoes were cultured in vitro, the JH-activated gene expression was repressed substantially if specific inhibitors of PLC or CaMKII were added to the medium together with JH. In newly emerged female mosquitoes, RNAi-mediated depletion of PLC or CaMKII considerably reduced the expression of JH-responsive genes, including the Krüppel homolog 1 gene (AaKr-h1) and the early trypsin gene (AaET). JH-induced loading of MET to the promoters of AaKr-h1 and AaET was weakened drastically when either PLC or CaMKII was inactivated in the cultured tissues. Therefore, the results suggest that the membrane-initiated signaling pathway modifies the DNA-binding activity of MET via phosphorylation and thus facilitates the genomic responses to JH. In summary, this study reveals an interplay of genomic and nongenomic signaling mechanisms of JH. PMID:25825754

  16. Activation of the AMP-Activated Protein Kinase (AMPK) by Nitrated Lipids in Endothelial Cells

    PubMed Central

    Wu, Yong; Dong, Yunzhou; Song, Ping; Zou, Ming-Hui

    2012-01-01

    The AMP-activated protein kinase (AMPK) is an important regulator of endothelial metabolic and functional homeostasis. Here, we examined the regulation of AMPK by nitrated oleic acid (OA-NO2) and investigated the implications in endothelial function. Treatment of bovine aortic endothelial cells (BAECs) with OA-NO2 induced a significant increase in both AMPK-Thr172 phosphorylation and AMPK activity as well as upregulation of heme oxygenase (HO)-1 and hypoxia-inducible factor (HIF)-1α. Pharmacologic inhibition or genetic ablation of HO-1 or HIF-1α abolished OA-NO2-induced AMPK phosphorylation. OA-NO2 induced a dramatic increase in extracellular signal-regulated kinase (ERK)1/2 phosphorylation that was abrogated by the HO-1 inhibitor, zinc deuteroporphyrin IX 2,4-bis-ethylene glycol (ZnBG). Inhibition of ERK1/2 using UO126 or PD98059 reduced but did not abolish OA-NO2-induced HIF-1α upregulation, suggesting that OA-NO2/HO-1-initiated HIF-1α induction is partially dependent on ERK1/2 activity. In addition, OA-NO2 enhanced endothelial intracellular Ca2+, an effect that was inhibited by the HIF-1α inhibitor, YC-1, and by HIF-1α siRNA. These results implicate the involvement of HIF-1α. Experiments using the Ca2+/calmodulin-dependent protein kinase kinase (CaMKK) inhibitor STO-609, the selective CaMKII inhibitor KN-93, and an isoform-specific siRNA demonstrated that OA-NO2-induced AMPK phosphorylation was dependent on CaMKKβ. Together, these results demonstrate that OA-NO2 activates AMPK in endothelial cells via an HO-1–dependent mechanism that increases HIF-1α protein expression and Ca2+/CaMKKβ activation. PMID:22363546

  17. The Activating Transcription Factor 3 Protein Suppresses the Oncogenic Function of Mutant p53 Proteins*

    PubMed Central

    Wei, Saisai; Wang, Hongbo; Lu, Chunwan; Malmut, Sarah; Zhang, Jianqiao; Ren, Shumei; Yu, Guohua; Wang, Wei; Tang, Dale D.; Yan, Chunhong

    2014-01-01

    Mutant p53 proteins (mutp53) often acquire oncogenic activities, conferring drug resistance and/or promoting cancer cell migration and invasion. Although it has been well established that such a gain of function is mainly achieved through interaction with transcriptional regulators, thereby modulating cancer-associated gene expression, how the mutp53 function is regulated remains elusive. Here we report that activating transcription factor 3 (ATF3) bound common mutp53 (e.g. R175H and R273H) and, subsequently, suppressed their oncogenic activities. ATF3 repressed mutp53-induced NFKB2 expression and sensitized R175H-expressing cancer cells to cisplatin and etoposide treatments. Moreover, ATF3 appeared to suppress R175H- and R273H-mediated cancer cell migration and invasion as a consequence of preventing the transcription factor p63 from inactivation by mutp53. Accordingly, ATF3 promoted the expression of the metastasis suppressor SHARP1 in mutp53-expressing cells. An ATF3 mutant devoid of the mutp53-binding domain failed to disrupt the mutp53-p63 binding and, thus, lost the activity to suppress mutp53-mediated migration, suggesting that ATF3 binds to mutp53 to suppress its oncogenic function. In line with these results, we found that down-regulation of ATF3 expression correlated with lymph node metastasis in TP53-mutated human lung cancer. We conclude that ATF3 can suppress mutp53 oncogenic function, thereby contributing to tumor suppression in TP53-mutated cancer. PMID:24554706

  18. Research progress of pharmacological activities and analytical methods for plant origin proteins.

    PubMed

    Li, Chun-hong; Chen, Cen; Xia, Zhi-ning; Yang, Feng-qing

    2015-07-01

    As one of the important active components of traditional Chinese medicine (TCM), plant origin active proteins have many significant pharmacological functions. According to researches on the plant origin active proteins reported in recent years, pharmacological effects include anti-tumor, immune regulation, anti-oxidant, anti-pathogeny microorganism, anti-thrombus, as well as hypolipidemic and hypoglycemic activities of plant origin were reviewed, respectively. On the other hand, the analytical methods including chromatography, spectroscopy, electrophoresis and mass spectrometry for plant origin proteins analysis were also summarized. The main purpose of this paper is providing a reference for future development and application of plant active proteins.

  19. Protein kinase A activation enhances β-catenin transcriptional activity through nuclear localization to PML bodies.

    PubMed

    Zhang, Mei; Mahoney, Emilia; Zuo, Tao; Manchanda, Parmeet K; Davuluri, Ramana V; Kirschner, Lawrence S

    2014-01-01

    The Protein Kinase A (PKA) and Wnt signaling cascades are fundamental pathways involved in cellular development and maintenance. In the osteoblast lineage, these pathways have been demonstrated functionally to be essential for the production of mineralized bone. Evidence for PKA-Wnt crosstalk has been reported both during tumorigenesis and during organogenesis, and the nature of the interaction is thought to rely on tissue and cell context. In this manuscript, we analyzed bone tumors arising from mice with activated PKA caused by mutation of the PKA regulatory subunit Prkar1a. In primary cells from these tumors, we observed relocalization of β-catenin to intranuclear punctuate structures, which were identified as PML bodies. Cellular redistribution of β-catenin could be recapitulated by pharmacologic activation of PKA. Using 3T3-E1 pre-osteoblasts as a model system, we found that PKA phosphorylation sites on β-catenin were required for nuclear re-localization. Further, β-catenin's transport to the nucleus was accompanied by an increase in canonical Wnt-dependent transcription, which also required the PKA sites. PKA-Wnt crosstalk in the cells was bi-directional, including enhanced interactions between β-catenin and the cAMP-responsive element binding protein (CREB) and transcriptional crosstalk between the Wnt and PKA signaling pathways. Increases in canonical Wnt/β-catenin signaling were associated with a decrease in the activity of the non-canonical Wnt/Ror2 pathway, which has been shown to antagonize canonical Wnt signaling. Taken together, this study provides a new understanding of the complex regulation of the subcellular distribution of β-catenin and its differential protein-protein interaction that can be modulated by PKA signaling. PMID:25299576

  20. Activation of 5' adenosine monophosphate-activated protein kinase blocks cumulus cell expansion through inhibition of protein synthesis during in vitro maturation in Swine.

    PubMed

    Santiquet, Nicolas; Sasseville, Maxime; Laforest, Martin; Guillemette, Christine; Gilchrist, Robert B; Richard, François J

    2014-08-01

    The serine/threonine kinase 5' adenosine monophosphate-activated protein kinase (AMPK), a heterotrimeric protein known as a metabolic switch, is involved in oocyte nuclear maturation in mice, cattle, and swine. The present study analyzed AMPK activation in cumulus cell expansion during in vitro maturation (IVM) of porcine cumulus-oocyte complexes (COC). 5-Aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) is a well-known activator of AMPK. It inhibited oocyte meiotic resumption in COC. Moreover, cumulus cell expansion did not occur in the presence of AICAR, demonstrating its marked impact on cumulus cells. Activation of AMPK was supported by AICAR-mediated phosphorylation of alpha AMPK subunits. Furthermore, the presence of AICAR increased glucose uptake, a classical response to activation of this metabolic switch in response to depleted cellular energy levels. Neither nuclear maturation nor cumulus expansion was reversed by glucosamine, an alternative substrate in hyaluronic acid synthesis, through the hexosamine biosynthetic pathway, which ruled out possible depletion of substrates. Both increased gap junction communication and phosphodiesterase activity in COC are dependent on protein synthesis during the initial hours of IVM; however, both were inhibited in the presence of AICAR, which supports the finding that activation of AMPK by AICAR mediated inhibition of protein synthesis. Moreover, this protein synthesis inhibition was equivalent to that of the well-known protein synthesis inhibitor cycloheximide, as observed on cumulus expansion and protein concentration. Finally, the phosphorylation level of selected kinases was investigated. The pattern of raptor phosphorylation is supportive of activation of AMPK-mediated inhibition of protein synthesis. In conclusion, AICAR-mediated AMPK activation in porcine COC inhibited cumulus cell expansion and protein synthesis. These results bring new considerations to the importance of this kinase in ovarian

  1. Total protein, animal protein and physical activity in relation to muscle mass in middle-aged and older Americans.

    PubMed

    Morris, Martha Savaria; Jacques, Paul F

    2013-04-14

    Resistance training is recognised as a good strategy for retarding age-related declines in muscle mass and strength. Recent studies have also highlighted the potential value of protein intakes in excess of present recommendations. The roles that leisure-time physical activity and protein quality play in the preservation of skeletal muscle during ageing, and how such influences interact in free-living people are unclear. We sought to clarify these issues using data collected on 2425 participants aged ≥ 50 years in the US National Health and Nutrition Examination Survey (2003-2006). We estimated subjects' usual intakes of total protein and beef from two 24 h diet recalls and computed the appendicular skeletal muscle mass index from anthropometric measures. Participants self-reported their physical activity levels. Analyses accounted for demographic factors and smoking. The association between muscle-strengthening activity and the appendicular skeletal muscle mass index varied with protein intake. Furthermore, among obese subjects with protein intakes < 70 g/d, those who performed such activities had a lower appendicular skeletal muscle mass index than those who were physically inactive. Protein intakes above the present recommendations were associated with benefits to obese subjects only. The appendicular skeletal muscle mass index of non-obese subjects who performed vigorous aerobic activities was consistently high; in obese subjects, it varied with protein intake. High-protein intake was associated with a modest increase in the appendicular skeletal muscle mass index in non-obese, physically inactive subjects. The present findings reinforce the idea that muscle-strengthening exercise preserves muscle when combined with adequate dietary protein. Vigorous aerobic activity may also help.

  2. Controlled activation of protein rotational dynamics using smart hydrogel tethering.

    PubMed

    Beech, Brenda M; Xiong, Yijia; Boschek, Curt B; Baird, Cheryl L; Bigelow, Diana J; McAteer, Kathleen; Squier, Thomas C

    2014-09-24

    Stimulus-responsive hydrogel materials that stabilize and control protein dynamics have the potential to enable a range of applications that take advantage of the inherent specificity and catalytic efficiencies of proteins. Here we describe the modular construction of a hydrogel using an engineered calmodulin (CaM) within a poly(ethylene glycol) (PEG) matrix that involves the reversible tethering of proteins through an engineered CaM-binding sequence. For these measurements, maltose binding protein (MBP) was isotopically labeled with (13)C and (15)N, permitting dynamic structural measurements using TROSY-HSQC NMR spectroscopy. The protein dynamics is suppressed upon initial formation of hydrogels, with a concomitant increase in protein stability. Relaxation of the hydrogel matrix following transient heating results in enhanced protein dynamics and resolution of substrate-induced large-amplitude domain rearrangements.

  3. RNA Remodeling Activity of DEAD Box Proteins Tuned by Protein Concentration, RNA Length, and ATP.

    PubMed

    Kim, Younghoon; Myong, Sua

    2016-09-01

    DEAD box RNA helicases play central roles in RNP biogenesis. We reported earlier that LAF-1, a DEAD box RNA helicase in C. elegans, dynamically interacts with RNA and that the interaction likely contributes to the fluidity of RNP droplets. Here we investigate the molecular basis of the interaction of RNA with LAF-1 and its human homolog, DDX3X. We show that both LAF-1 and DDX3X, at low concentrations, are monomers that induce tight compaction of single-stranded RNA. At high concentrations, the proteins are multimeric and dynamically interact with RNA in an RNA length-dependent manner. The dynamic LAF-1-RNA interaction stimulates RNA annealing activity. ATP adversely affects the RNA remodeling ability of LAF-1 by suppressing the affinity, dynamics, and annealing activity of LAF-1, suggesting that ATP may promote disassembly of the RNP complex. Based on our results, we postulate a plausible molecular mechanism underlying the dynamic equilibrium of the LAF-1 RNP complex. PMID:27546789

  4. Curcumin attenuates diet-induced hepatic steatosis by activating AMP-activated protein kinase.

    PubMed

    Um, Min Young; Hwang, Kwang Hyun; Ahn, Jiyun; Ha, Tae Youl

    2013-09-01

    Curcumin is a well-known component of traditional turmeric (Curcuma longa), which has been reported to prevent obesity and diabetes. However, the effect of curcumin on hepatic lipid metabolism remains unclear. The aim of this study was to examine the effects of curcumin on hepatic steatosis in high-fat/cholesterol diet (HFD)-induced obese mice. Male C57BL/6J mice were fed a normal diet (ND), HFD or HFD with 0.15% curcumin (HFD+C) for 11 weeks. We found that curcumin significantly lowered the body-weight and adipose tissue weight of mice in the HFD+C group compared with the findings for the HFD group (p < 0.05). The levels of total cholesterol, fasting glucose and insulin in serum were decreased, and HFD-induced impairment of insulin sensitivity was improved by curcumin supplementation (p < 0.05). Curcumin protected against the development of hepatic steatosis by reducing hepatic fat accumulation. Moreover, curcumin activated AMP-activated protein kinase (AMPK) and elevated the gene expression of peroxisome proliferator-activated receptor alpha. By contrast, curcumin suppressed the HFD-mediated increases in sterol regulatory element-binding protein-1, acetyl-CoA carboxylase 1, fatty acid synthase and cluster of differentiation 36 expression. Taken together, these findings indicate that curcumin attenuates HFD-induced hepatic steatosis by regulating hepatic lipid metabolism via AMPK activation, suggesting its use as a therapeutic for hepatic steatosis.

  5. Traumatic brain injury decreases AMP-activated protein kinase activity and pharmacological enhancement of its activity improves cognitive outcome.

    PubMed

    Hill, Julia L; Kobori, Nobuhide; Zhao, Jing; Rozas, Natalia S; Hylin, Michael J; Moore, Anthony N; Dash, Pramod K

    2016-10-01

    Prolonged metabolic suppression in the brain is a well-characterized secondary pathology of both experimental and clinical traumatic brain injury (TBI). AMP-activated kinase (AMPK) acts as a cellular energy sensor that, when activated, regulates various metabolic and catabolic pathways to decrease ATP consumption and increase ATP synthesis. As energy availability after TBI is suppressed, we questioned if increasing AMPK activity after TBI would improve cognitive outcome. TBI was delivered using the electromagnetic controlled cortical impact model on male Sprague-Dawley rats (275-300 g) and C57BL/6 mice (20-25 g). AMPK activity within the injured parietal cortex and ipsilateral hippocampus was inferred by western blots using phospho-specific antibodies. The consequences of acute manipulation of AMPK signaling on cognitive function were assessed using the Morris water maze task. We found that AMPK activity is decreased as a result of injury, as indicated by reduced AMPK phosphorylation and corresponding changes in the phosphorylation of its downstream targets: ribosomal protein S6 and Akt Substrate of 160 kDa (AS160). Increasing AMPK activity after injury using the drugs 5-amino-1-β-d-ribofuranosyl-imidazole-4-carboxamide or metformin did not affect spatial learning, but significantly improved spatial memory. Taken together, our results suggest that decreased AMPK activity after TBI may contribute to the cellular energy crisis in the injured brain, and that AMPK activators may have therapeutic utility. Increased phosphorylation of Thr172 activates AMP-activated protein kinase (AMPK) under conditions of low cellular energy availability. This leads to inhibition of energy consuming, while activating energy generating, processes. Hill et al., present data to indicate that TBI decreases Thr172 phosphorylation and that its stimulation by pharmacological agents offers neuroprotection and improves memory. These results suggest that decreased AMPK phosphorylation after

  6. New Tricks for Old Proteins: Single Mutations in a Nonenzymatic Protein Give Rise to Various Enzymatic Activities.

    PubMed

    Moroz, Yurii S; Dunston, Tiffany T; Makhlynets, Olga V; Moroz, Olesia V; Wu, Yibing; Yoon, Jennifer H; Olsen, Alissa B; McLaughlin, Jaclyn M; Mack, Korrie L; Gosavi, Pallavi M; van Nuland, Nico A J; Korendovych, Ivan V

    2015-12-01

    Design of a new catalytic function in proteins, apart from its inherent practical value, is important for fundamental understanding of enzymatic activity. Using a computationally inexpensive, minimalistic approach that focuses on introducing a single highly reactive residue into proteins to achieve catalysis we converted a 74-residue-long C-terminal domain of calmodulin into an efficient esterase. The catalytic efficiency of the resulting stereoselective, allosterically regulated catalyst, nicknamed AlleyCatE, is higher than that of any previously reported de novo designed esterases. The simplicity of our design protocol should complement and expand the capabilities of current state-of-art approaches to protein design. These results show that even a small nonenzymatic protein can efficiently attain catalytic activities in various reactions (Kemp elimination, ester hydrolysis, retroaldol reaction) as a result of a single mutation. In other words, proteins can be just one mutation away from becoming entry points for subsequent evolution.

  7. New Tricks for Old Proteins: Single Mutations in a Nonenzymatic Protein Give Rise to Various Enzymatic Activities.

    PubMed

    Moroz, Yurii S; Dunston, Tiffany T; Makhlynets, Olga V; Moroz, Olesia V; Wu, Yibing; Yoon, Jennifer H; Olsen, Alissa B; McLaughlin, Jaclyn M; Mack, Korrie L; Gosavi, Pallavi M; van Nuland, Nico A J; Korendovych, Ivan V

    2015-12-01

    Design of a new catalytic function in proteins, apart from its inherent practical value, is important for fundamental understanding of enzymatic activity. Using a computationally inexpensive, minimalistic approach that focuses on introducing a single highly reactive residue into proteins to achieve catalysis we converted a 74-residue-long C-terminal domain of calmodulin into an efficient esterase. The catalytic efficiency of the resulting stereoselective, allosterically regulated catalyst, nicknamed AlleyCatE, is higher than that of any previously reported de novo designed esterases. The simplicity of our design protocol should complement and expand the capabilities of current state-of-art approaches to protein design. These results show that even a small nonenzymatic protein can efficiently attain catalytic activities in various reactions (Kemp elimination, ester hydrolysis, retroaldol reaction) as a result of a single mutation. In other words, proteins can be just one mutation away from becoming entry points for subsequent evolution. PMID:26555770

  8. Activated protein C cofactor function of protein S: a novel role for a γ-carboxyglutamic acid residue.

    PubMed

    Ahnström, Josefin; Andersson, Helena M; Canis, Kevin; Norstrøm, Eva; Yu, Yao; Dahlbäck, Björn; Panico, Maria; Morris, Howard R; Crawley, James T B; Lane, David A

    2011-06-16

    Protein S has an important anticoagulant function by acting as a cofactor for activated protein C (APC). We recently reported that the EGF1 domain residue Asp95 is critical for APC cofactor function. In the present study, we examined whether additional interaction sites within the Gla domain of protein S might contribute to its APC cofactor function. We examined 4 residues, composing the previously reported "Face1" (N33S/P35T/E36A/Y39V) variant, as single point substitutions. Of these protein S variants, protein S E36A was found to be almost completely inactive using calibrated automated thrombography. In factor Va inactivation assays, protein S E36A had 89% reduced cofactor activity compared with wild-type protein S and was almost completely inactive in factor VIIIa inactivation; phospholipid binding was, however, normal. Glu36 lies outside the ω-loop that mediates Ca(2+)-dependent phospholipid binding. Using mass spectrometry, it was nevertheless confirmed that Glu36 is γ-carboxylated. Our finding that Gla36 is important for APC cofactor function, but not for phospholipid binding, defines a novel function (other than Ca(2+) coordination/phospholipid binding) for a Gla residue in vitamin K-dependent proteins. It also suggests that residues within the Gla and EGF1 domains of protein S act cooperatively for its APC cofactor function.

  9. Activated platelets rescue apoptotic cells via paracrine activation of EGFR and DNA-dependent protein kinase

    PubMed Central

    Au, A E-L; Sashindranath, M; Borg, R J; Kleifeld, O; Andrews, R K; Gardiner, E E; Medcalf, R L; Samson, A L

    2014-01-01

    Platelet activation is a frontline response to injury, not only essential for clot formation but also important for tissue repair. Indeed, the reparative influence of platelets has long been exploited therapeutically where application of platelet concentrates expedites wound recovery. Despite this, the mechanisms of platelet-triggered cytoprotection are poorly understood. Here, we show that activated platelets accumulate in the brain to exceptionally high levels following injury and release factors that potently protect neurons from apoptosis. Kinomic microarray and subsequent kinase inhibitor studies showed that platelet-based neuroprotection relies upon paracrine activation of the epidermal growth factor receptor (EGFR) and downstream DNA-dependent protein kinase (DNA-PK). This same anti-apoptotic cascade stimulated by activated platelets also provided chemo-resistance to several cancer cell types. Surprisingly, deep proteomic profiling of the platelet releasate failed to identify any known EGFR ligand, indicating that activated platelets release an atypical activator of the EGFR. This study is the first to formally associate platelet activation to EGFR/DNA-PK – an endogenous cytoprotective cascade. PMID:25210793

  10. Activation of p38 Mitogen-Activated Protein Kinase Promotes Epidermal Growth Factor Receptor Internalization

    PubMed Central

    Vergarajauregui, Silvia; Miguel, Anitza San; Puertollano, Rosa

    2006-01-01

    Endocytic trafficking plays an important role in the regulation of the epidermal growth factor receptor (EGFR). To address if cellular kinases regulate EGFR internalization, we used anisomycin, a potent activator of kinase cascades in mammalian cells, especially the stress-activated mitogen-activated protein (MAP) kinase subtypes. Here, we report that activation of p38 MAP kinase by anisomycin is sufficient to induce internalization of EGFR. Anisomycin and EGF employ different mechanisms to promote EGFR endocytosis as anisomycin-induced internalization does not require tyrosine kinase activity or ubiquitination of the receptor. In addition, anisomycin treatment did not result in delivery and degradation of EGFR at lysosomes. Incubation with a specific inhibitor of p38, or depletion of endogenous p38 by small interfering RNAs, abolished anisomycin-induced internalization of EGFR while having no effect on transferrin endocytosis, indicating that the effect of p38 activation on EGFR endocytosis is specific. Interestingly, inhibition of p38 activation also abolished endocytosis of EGFR induced by UV radiation. Our results reveal a novel role for p38 in the regulation of EGFR endocytosis and suggest that stimulation of EGFR internalization by p38 might represent a general mechanism to prevent generation of proliferative or anti-apoptotic signals under stress conditions. PMID:16683917

  11. GSK621 Targets Glioma Cells via Activating AMP-Activated Protein Kinase Signalings

    PubMed Central

    Jiang, Hong; Liu, Wei; Zhan, Shi-Kun; Pan, Yi-Xin; Bian, Liu-Guan; Sun, Bomin; Sun, Qing-Fang; Pan, Si-Jian

    2016-01-01

    Here, we studied the anti-glioma cell activity by a novel AMP-activated protein kinase (AMPK) activator GSK621. We showed that GSK621 was cytotoxic to human glioma cells (U87MG and U251MG lines), possibly via provoking caspase-dependent apoptotic cell death. Its cytotoxicity was alleviated by caspase inhibitors. GSK621 activated AMPK to inhibit mammalian target of rapamycin (mTOR) and downregulate Tetraspanin 8 (Tspan8) in glioma cells. AMPK inhibition, through shRNA knockdown of AMPKα or introduction of a dominant negative (T172A) AMPKα, almost reversed GSK621-induced AMPK activation, mTOR inhibition and Tspan8 degradation. Consequently, GSK621’s cytotoxicity in glioma cells was also significantly attenuated by AMPKα knockdown or mutation. Further studies showed that GSK621, at a relatively low concentration, significantly potentiated temozolomide (TMZ)’s sensitivity and lethality against glioma cells. We summarized that GSK621 inhibits human glioma cells possibly via activating AMPK signaling. This novel AMPK activator could be a novel and promising anti-glioma cell agent. PMID:27532105

  12. Xylazine Activates Adenosine Monophosphate-Activated Protein Kinase Pathway in the Central Nervous System of Rats

    PubMed Central

    Shi, Xing-Xing; Yin, Bai-Shuang; Yang, Peng; Chen, Hao; Li, Xin; Su, Li-Xue; Fan, Hong-Gang; Wang, Hong-Bin

    2016-01-01

    Xylazine is a potent analgesic extensively used in veterinary and animal experimentation. Evidence exists that the analgesic effect can be inhibited using adenosine 5’-monophosphate activated protein kinase (AMPK) inhibitors. Considering this idea, the aim of this study was to investigate whether the AMPK signaling pathway is involved in the central analgesic mechanism of xylazine in the rat. Xylazine was administrated via the intraperitoneal route. Sprague-Dawley rats were sacrificed and the cerebral cortex, cerebellum, hippocampus, thalamus and brainstem were collected for determination of liver kinase B1 (LKB1) and AMPKα mRNA expression using quantitative real-time polymerase chain reaction (qPCR), and phosphorylated LKB1 and AMPKα levels using western blot. The results of our study showed that compared with the control group, xylazine induced significant increases in AMPK activity in the cerebral cortex, hippocampus, thalamus and cerebellum after rats received xylazine (P < 0.01). Increased AMPK activities were accompanied with increased phosphorylation levels of LKB1 in corresponding regions of rats. The protein levels of phosphorylated LKB1 and AMPKα in these regions returned or tended to return to control group levels. However, in the brainstem, phosphorylated LKB1 and AMPKα protein levels were decreased by xylazine compared with the control (P < 0.05). In conclusion, our data indicates that xylazine alters the activities of LKB1 and AMPK in the central nervous system of rats, which suggests that xylazine affects the regulatory signaling pathway of the analgesic mechanism in the rat brain. PMID:27049320

  13. Multiple protein-protein interactions converging on the Prp38 protein during activation of the human spliceosome.

    PubMed

    Schütze, Tonio; Ulrich, Alexander K C; Apelt, Luise; Will, Cindy L; Bartlick, Natascha; Seeger, Martin; Weber, Gert; Lührmann, Reinhard; Stelzl, Ulrich; Wahl, Markus C

    2016-02-01

    Spliceosomal Prp38 proteins contain a conserved amino-terminal domain, but only higher eukaryotic orthologs also harbor a carboxy-terminal RS domain, a hallmark of splicing regulatory SR proteins. We show by crystal structure analysis that the amino-terminal domain of human Prp38 is organized around three pairs of antiparallel α-helices and lacks similarities to RNA-binding domains found in canonical SR proteins. Instead, yeast two-hybrid analyses suggest that the amino-terminal domain is a versatile protein-protein interaction hub that possibly binds 12 other spliceosomal proteins, most of which are recruited at the same stage as Prp38. By quantitative, alanine surface-scanning two-hybrid screens and biochemical analyses we delineated four distinct interfaces on the Prp38 amino-terminal domain. In vitro interaction assays using recombinant proteins showed that Prp38 can bind at least two proteins simultaneously via two different interfaces. Addition of excess Prp38 amino-terminal domain to in vitro splicing assays, but not of an interaction-deficient mutant, stalled splicing at a precatalytic stage. Our results show that human Prp38 is an unusual SR protein, whose amino-terminal domain is a multi-interface protein-protein interaction platform that might organize the relative positioning of other proteins during splicing. PMID:26673105

  14. Protein Conformational Gating of Enzymatic Activity in Xanthine Oxidoreductase

    SciTech Connect

    Ishikita, Hiroshi; Eger, Bryan T.; Okamoto, Ken; Nishino, Takeshi; Pai, Emil F.

    2012-05-24

    In mammals, xanthine oxidoreductase can exist as xanthine dehydrogenase (XDH) and xanthine oxidase (XO). The two enzymes possess common redox active cofactors, which form an electron transfer (ET) pathway terminated by a flavin cofactor. In spite of identical protein primary structures, the redox potential difference between XDH and XO for the flavin semiquinone/hydroquinone pair (E{sub sq/hq}) is {approx}170 mV, a striking difference. The former greatly prefers NAD{sup +} as ultimate substrate for ET from the iron-sulfur cluster FeS-II via flavin while the latter only accepts dioxygen. In XDH (without NAD{sup +}), however, the redox potential of the electron donor FeS-II is 180 mV higher than that for the acceptor flavin, yielding an energetically uphill ET. On the basis of new 1.65, 2.3, 1.9, and 2.2 {angstrom} resolution crystal structures for XDH, XO, the NAD{sup +}- and NADH-complexed XDH, E{sub sq/hq} were calculated to better understand how the enzyme activates an ET from FeS-II to flavin. The majority of the E{sub sq/hq} difference between XDH and XO originates from a conformational change in the loop at positions 423-433 near the flavin binding site, causing the differences in stability of the semiquinone state. There was no large conformational change observed in response to NAD{sup +} binding at XDH. Instead, the positive charge of the NAD{sup +} ring, deprotonation of Asp429, and capping of the bulk surface of the flavin by the NAD{sup +} molecule all contribute to altering E{sub sq/hq} upon NAD{sup +} binding to XDH.

  15. Rheb Inhibits Protein Synthesis by Activating the PERK-eIF2α Signaling Cascade

    PubMed Central

    Tyagi, Richa; Shahani, Neelam; Gorgen, Lindsay; Ferretti, Max; Pryor, William; Chen, Po Yu; Swarnkar, Supriya; Worley, Paul F.; Karbstein, Katrin; Snyder, Solomon H.; Subramaniam, Srinivasa

    2015-01-01

    SUMMARY Rheb, a ubiquitous small GTPase, is well known to bind and activate mTOR, which augments protein synthesis. Inhibition of protein synthesis is also physiologically regulated. Thus, with cell stress the unfolded protein response system leads to phosphorylation of the initiation factor eIF2α and arrest of protein synthesis. We now demonstrate a major role for Rheb in inhibiting protein synthesis through enhancing the phosphorylation of eIF2α by protein kinase-like endoplasmic reticulum kinase (PERK). Interplay between the stimulatory and inhibitory roles of Rheb may enable cells to modulate protein synthesis in response to varying environmental stresses. PMID:25660019

  16. Porins from Salmonella enterica Serovar Typhimurium Activate the Transcription Factors Activating Protein 1 and NF-κB through the Raf-1-Mitogen-Activated Protein Kinase Cascade

    PubMed Central

    Galdiero, Massimiliano; Vitiello, Mariateresa; Sanzari, Emma; D’Isanto, Marina; Tortora, Annalisa; Longanella, Anna; Galdiero, Stefania

    2002-01-01

    In this study we examined the ability of Salmonella enterica serovar Typhimurium porins to activate activating protein 1 (AP-1) and nuclear factor κB (NF-κB) through the mitogen-activated protein kinase (MAPK) cascade, and we identified the AP-1-induced protein subunits. Our results demonstrate that these enzymes may participate in cell signaling pathways leading to AP-1 and NF-κB activation following porin stimulation of cells. Raf-1 was phosphorylated in response to the treatment of U937 cells with porins; moreover, the porin-mediated increase in Raf-1 phosphorylation is accompanied by the phosphorylation of MAPK kinase 1/2 (MEK1/2), p38, extracellular-signal-regulated kinase 1/2, and c-Jun N-terminal kinase. We used three different inhibitors of phosphorylation pathways: 2′-amino-3′-methoxyflavone (PD-098059), a selective inhibitor of MEK1 activator and the MAPK cascade; 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580), a specific inhibitor of the p38 pathway; and 7β-acetoxy-1α,6β,9α-trihydroxy-8,13-epoxy-labd-14-en-11-one (forskolin), an inhibitor at the level of Raf-1 kinase. PD-098059 pretreatment of cells decreases AP-1 and NF-κB activation by lipopolysaccharide (LPS) but not by porins, and SB203580 pretreatment of cells decreases mainly AP-1 and NF-κB activation by porins; in contrast, forskolin pretreatment of cells does not affect AP-1 and NF-κB activation following either porin or LPS stimulation. Our data suggest that the p38 signaling pathway mainly regulates AP-1 and NF-κB activation in cells treated with S. enterica serovar Typhimurium porins. Antibody electrophoretic mobility shift assays showed that JunD and c-Fos binding is found in cells treated with porins, in cells treated with LPS, and in unstimulated cells. However, by 30 to 60 min of stimulation, a different complex including c-Jun appears in cells treated with porins or LPS, while the Fra-2 subunit is present only after porin stimulation

  17. HMGA proteins as modulators of chromatin structure during transcriptional activation

    PubMed Central

    Ozturk, Nihan; Singh, Indrabahadur; Mehta, Aditi; Braun, Thomas; Barreto, Guillermo

    2013-01-01

    High mobility group (HMG) proteins are the most abundant non-histone chromatin associated proteins. HMG proteins bind to DNA and nucleosome and alter the structure of chromatin locally and globally. Accessibility to DNA within chromatin is a central factor that affects DNA-dependent nuclear processes, such as transcription, replication, recombination, and repair. HMG proteins associate with different multi-protein complexes to regulate these processes by mediating accessibility to DNA. HMG proteins can be subdivided into three families: HMGA, HMGB, and HMGN. In this review, we will focus on recent advances in understanding the function of HMGA family members, specifically their role in gene transcription regulation during development and cancer. PMID:25364713

  18. Studies on the activating enzyme for iron protein of nitrogenase from Rhodospirillum rubrum.

    PubMed

    Saari, L L; Pope, M R; Murrell, S A; Ludden, P W

    1986-04-15

    Removal of ADP-ribose from the iron protein of nitrogenase by activating enzyme resulted in the activation of the inactive iron protein. A radioassay that directly measured the initial velocity of the activation was developed using iron protein radiolabeled with either [8-3H]- or [G-32P]ADP-ribose. The release of radiolabeled ADP-ribose by activating enzyme was linearly correlated with the increase in the specific activity of the iron protein as measured by acetylene reduction. Both ATP and MnCl2 were required for the activation of inactive iron protein. The optimal ratio of [MnCl2]/[ATP] in the radioassay was 2:1, and the optimal concentrations were 4 mM and 2 mM for [MnCl2] and [ATP], respectively. The Km for inactive iron protein was 74 microM and the Vmax was 628 pmol of [32P] ADP-ribose released min-1 microgram of activating enzyme-1. Adenosine, cytidine, guanosine, or uridine mono-, di-, or triphosphates did not substitute for ATP in the activation of native iron protein. Activating enzyme removed ADP-ribose from oxygen-denatured iron protein in the absence of ATP. ADP, ADP-ribose, pyrophosphate, and high concentrations of NaCl inhibited activating enzyme activity. PMID:3082874

  19. Regulation of AMP-activated protein kinase by natural and synthetic activators

    PubMed Central

    Grahame Hardie, David

    2015-01-01

    The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is almost universally expressed in eukaryotic cells. While it appears to have evolved in single-celled eukaryotes to regulate energy balance in a cell-autonomous manner, during the evolution of multicellular animals its role has become adapted so that it also regulates energy balance at the whole body level, by responding to hormones that act primarily on the hypothalamus. AMPK monitors energy balance at the cellular level by sensing the ratios of AMP/ATP and ADP/ATP, and recent structural analyses of the AMPK heterotrimer that have provided insight into the complex mechanisms for these effects will be discussed. Given the central importance of energy balance in diseases that are major causes of morbidity or death in humans, such as type 2 diabetes, cancer and inflammatory disorders, there has been a major drive to develop pharmacological activators of AMPK. Many such activators have been described, and the various mechanisms by which these activate AMPK will be discussed. A particularly large class of AMPK activators are natural products of plants derived from traditional herbal medicines. While the mechanism by which most of these activate AMPK has not yet been addressed, I will argue that many of them may be defensive compounds produced by plants to deter infection by pathogens or grazing by insects or herbivores, and that many of them will turn out to be inhibitors of mitochondrial function. PMID:26904394

  20. Latrepirdine is a potent activator of AMP-activated protein kinase and reduces neuronal excitability

    PubMed Central

    Weisová, P; Alvarez, S P; Kilbride, S M; Anilkumar, U; Baumann, B; Jordán, J; Bernas, T; Huber, H J; Düssmann, H; Prehn, J H M

    2013-01-01

    Latrepirdine/Dimebon is a small-molecule compound with attributed neurocognitive-enhancing activities, which has recently been tested in clinical trials for the treatment of Alzheimer's and Huntington's disease. Latrepirdine has been suggested to be a neuroprotective agent that increases mitochondrial function, however the molecular mechanisms underlying these activities have remained elusive. We here demonstrate that latrepirdine, at (sub)nanomolar concentrations (0.1 nM), activates the energy sensor AMP-activated protein kinase (AMPK). Treatment of primary neurons with latrepirdine increased intracellular ATP levels and glucose transporter 3 translocation to the plasma membrane. Latrepirdine also increased mitochondrial uptake of the voltage-sensitive probe TMRM. Gene silencing of AMPKα or its upstream kinases, LKB1 and CaMKKβ, inhibited this effect. However, studies using the plasma membrane potential indicator DisBAC2(3) demonstrated that the effects of latrepirdine on TMRM uptake were largely mediated by plasma membrane hyperpolarization, precluding a purely ‘mitochondrial' mechanism of action. In line with a stabilizing effect of latrepirdine on plasma membrane potential, pretreatment with latrepirdine reduced spontaneous Ca2+ oscillations as well as glutamate-induced Ca2+ increases in primary neurons, and protected neurons against glutamate toxicity. In conclusion, our experiments demonstrate that latrepirdine is a potent activator of AMPK, and suggest that one of the main pharmacological activities of latrepirdine is a reduction in neuronal excitability. PMID:24150226

  1. Regulation of AMP-activated protein kinase by natural and synthetic activators.

    PubMed

    Grahame Hardie, David

    2016-01-01

    The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is almost universally expressed in eukaryotic cells. While it appears to have evolved in single-celled eukaryotes to regulate energy balance in a cell-autonomous manner, during the evolution of multicellular animals its role has become adapted so that it also regulates energy balance at the whole body level, by responding to hormones that act primarily on the hypothalamus. AMPK monitors energy balance at the cellular level by sensing the ratios of AMP/ATP and ADP/ATP, and recent structural analyses of the AMPK heterotrimer that have provided insight into the complex mechanisms for these effects will be discussed. Given the central importance of energy balance in diseases that are major causes of morbidity or death in humans, such as type 2 diabetes, cancer and inflammatory disorders, there has been a major drive to develop pharmacological activators of AMPK. Many such activators have been described, and the various mechanisms by which these activate AMPK will be discussed. A particularly large class of AMPK activators are natural products of plants derived from traditional herbal medicines. While the mechanism by which most of these activate AMPK has not yet been addressed, I will argue that many of them may be defensive compounds produced by plants to deter infection by pathogens or grazing by insects or herbivores, and that many of them will turn out to be inhibitors of mitochondrial function. PMID:26904394

  2. AMP-ACTIVATED PROTEIN KINASE ACTIVATION AS A STRATEGY FOR PROTECTING VASCULAR ENDOTHELIAL FUNCTION

    PubMed Central

    Zou, Ming-Hui; Wu, Yong

    2010-01-01

    SUMMARY 1. AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase involved in the regulation of cellular and organismal metabolism. AMPK has a heterotrimeric structure, consisting of a catalytic α-subunit and regulatory β- and γ-subunits, each of which has two or more isoforms that are differentially expressed in various tissues and that arise from distinct genes. The AMPK system acts as a sensor of cellular energy status that is conserved in all eukaryotic cells. In addition, AMPK is activated by physiological stimuli and oxidants. 2. The importance of AMPK in cardiovascular functions is best demonstrated by recent studies showing that widely used drugs, including statins, metformin and rosiglitazone, execute cardiovascular protective effects at least partly through the activation of AMPK. As a consequence, AMPK has been proposed as a candidate target for therapeutic intervention in the treatment of both Type 2 diabetes and metabolic syndrome owing to its central role in the regulation of energy balance; it may also have a role in weight control. 3. In the present brief review, we summarize the recent progress of AMPK signalling and regulation focusing on vascular endothelial cells. We further hypothesize that AMPK is a dual sensor for energy and redox status within a cell and AMPK may be a therapeutic target for protecting vascular endothelial function. PMID:18177481

  3. Role of diacylglycerol-regulated protein kinase C isotypes in growth factor activation of the Raf-1 protein kinase.

    PubMed

    Cai, H; Smola, U; Wixler, V; Eisenmann-Tappe, I; Diaz-Meco, M T; Moscat, J; Rapp, U; Cooper, G M

    1997-02-01

    The Raf protein kinases function downstream of Ras guanine nucleotide-binding proteins to transduce intracellular signals from growth factor receptors. Interaction with Ras recruits Raf to the plasma membrane, but the subsequent mechanism of Raf activation has not been established. Previous studies implicated hydrolysis of phosphatidylcholine (PC) in Raf activation; therefore, we investigated the role of the epsilon isotype of protein kinase C (PKC), which is stimulated by PC-derived diacylglycerol, as a Raf activator. A dominant negative mutant of PKC epsilon inhibited both proliferation of NIH 3T3 cells and activation of Raf in COS cells. Conversely, overexpression of active PKC epsilon stimulated Raf kinase activity in COS cells and overcame the inhibitory effects of dominant negative Ras in NIH 3T3 cells. PKC epsilon also stimulated Raf kinase in baculovirus-infected Spodoptera frugiperda Sf9 cells and was able to directly activate Raf in vitro. Consistent with its previously reported activity as a Raf activator in vitro, PKC alpha functioned similarly to PKC epsilon in both NIH 3T3 and COS cell assays. In addition, constitutively active mutants of both PKC alpha and PKC epsilon overcame the inhibitory effects of dominant negative mutants of the other PKC isotype, indicating that these diacylglycerol-regulated PKCs function as redundant activators of Raf-1 in vivo.

  4. 2-Octynoic Acid Inhibits Hepatitis C Virus Infection through Activation of AMP-Activated Protein Kinase

    PubMed Central

    Yang, Darong; Xue, Binbin; Wang, Xiaohong; Yu, Xiaoyan; Liu, Nianli; Gao, Yimin; Liu, Chen; Zhu, Haizhen

    2013-01-01

    Many chronic hepatitis C virus (HCV)-infected patients with current therapy do not clear the virus. It is necessary to find novel treatments. The effect of 2-octynoic acid (2-OA) on HCV infection in human hepatocytes was examined. The mechanism of 2-OA antiviral activity was explored. Our data showed that 2-OA abrogated lipid accumulation in HCV replicon cells and virus-infected hepatocytes. It suppressed HCV RNA replication and infectious virus production with no cytotoxicity to the host cells. 2-OA did not affect hepatitis B virus replication in HepG2.2.15 cells derived from HepG2 cells transfected with full genome of HBV. Further study demonstrated that 2-OA activated AMP-activated protein kinase (AMPK) and inhibited acetyl-CoA carboxylase in viral-infected cells. Compound C, a specific inhibitor of AMPK, inhibited AMPK activity and reversed the reduction of intracellular lipid accumulation and the antiviral effect of 2-OA. Knockdown of AMPK expression by RNA interference abolished the activation of AMPK by 2-OA and blocked 2-OA antiviral activity. Interestingly, 2-OA induced interferon-stimulated genes (ISGs) and inhibited microRNA-122 (miR-122) expression in virus-infected hepatocytes. MiR-122 overexpression reversed the antiviral effect of 2-OA. Furthermore, knockdown of AMPK expression reversed both the induction of ISGs and suppression of miR-122 by 2-OA, implying that activated AMPK induces the intracellular innate response through the induction of ISGs and inhibiting miR-122 expression. 2-OA inhibits HCV infection through regulation of innate immune response by activated AMPK. These findings reveal a novel mechanism by which active AMPK inhibits HCV infection. 2-OA and its derivatives hold promise for novel drug development for chronic hepatitis C. PMID:23741428

  5. Exposure to Hydrogen Peroxide Induces Oxidation and Activation of AMP-activated Protein Kinase*

    PubMed Central

    Zmijewski, Jaroslaw W.; Banerjee, Sami; Bae, Hongbeom; Friggeri, Arnaud; Lazarowski, Eduardo R.; Abraham, Edward

    2010-01-01

    Although metabolic conditions associated with an increased AMP/ATP ratio are primary factors in the activation of 5′-adenosine monophosphate-activated protein kinase (AMPK), a number of recent studies have shown that increased intracellular levels of reactive oxygen species can stimulate AMPK activity, even without a decrease in cellular levels of ATP. We found that exposure of recombinant AMPKαβγ complex or HEK 293 cells to H2O2 was associated with increased kinase activity and also resulted in oxidative modification of AMPK, including S-glutathionylation of the AMPKα and AMPKβ subunits. In experiments using C-terminal truncation mutants of AMPKα (amino acids 1–312), we found that mutation of cysteine 299 to alanine diminished the ability of H2O2 to induce kinase activation, and mutation of cysteine 304 to alanine totally abrogated the enhancing effect of H2O2 on kinase activity. Similar to the results obtained with H2O2-treated HEK 293 cells, activation and S-glutathionylation of the AMPKα subunit were present in the lungs of acatalasemic mice or mice treated with the catalase inhibitor aminotriazole, conditions in which intracellular steady state levels of H2O2 are increased. These results demonstrate that physiologically relevant concentrations of H2O2 can activate AMPK through oxidative modification of the AMPKα subunit. The present findings also imply that AMPK activation, in addition to being a response to alterations in intracellular metabolic pathways, is directly influenced by cellular redox status. PMID:20729205

  6. The Saccharomyces cerevisiae PUT3 activator protein associates with proline-specific upstream activation sequences.

    PubMed Central

    Siddiqui, A H; Brandriss, M C

    1989-01-01

    The PUT1 and PUT2 genes encoding the enzymes of the proline utilization pathway of Saccharomyces cerevisiae are induced by proline and activated by the product of the PUT3 gene. Two upstream activation sequences (UASs) in the PUT1 promoter were identified by homology to the PUT2 UAS. Deletion analysis of the two PUT1 UASs showed that they were functionally independent and additive in producing maximal levels of gene expression. The consensus PUT UAS is a 21-base-pair partially palindromic sequence required in vivo for induction of both genes. The results of a gel mobility shift assay demonstrated that the proline-specific UAS is the binding site of a protein factor. In vitro complex formation was observed in crude extracts of yeast strains carrying either a single genomic copy of the PUT3 gene or the cloned PUT3 gene on a 2 microns plasmid, and the binding was dosage dependent. DNA-binding activity was not observed in extracts of strains carrying either a put3 mutation that caused a noninducible (Put-) phenotype or a deletion of the gene. Wild-type levels of complex formation were observed in an extract of a strain carrying an allele of PUT3 that resulted in a constitutive (Put+) phenotype. Extracts from a strain carrying a PUT3-lacZ gene fusion formed two complexes of slower mobility than the wild-type complex. We conclude that the PUT3 product is either a DNA-binding protein or part of a DNA-binding complex that recognizes the UASs of both PUT1 and PUT2. Binding was observed in extracts of a strain grown in the presence or absence of proline, demonstrating the constitutive nature of the DNA-protein interaction. Images PMID:2689862

  7. The Escherichia coli uropathogenic-specific-protein-associated immunity protein 3 (Imu3) has nucleic acid -binding activity

    PubMed Central

    2014-01-01

    Background The Escherichia coli uropathogenic-specific protein (Usp) is a bacteriocin-like genotoxin, active against mammalian cells and associated with E. coli strains that provoke pyelonephritis, prostatitis and bacteraemia. Usp is encoded by a small pathogenicity island with three downstream small open reading frames (Imu1-3) that are believed to provide immunity to the producer. To prevent host suicide, colicins, bacteriocins of E. coli, form tight complexes with their cognate immunity proteins. Colicin – immunity protein complexes are among the strongest protein complexes known. Here, the Usp associated immunity protein 3 (Imu3) was partially characterized to gain insight into its role and mechanism of activity. Results Isolation and partial characterisation of the Usp-associated immunity protein-3 (Imu3) revealed that, while Usp and Imu3 do not form a high affinity complex, Imu3 exhibits DNA and RNA binding activity. Imu3 was also shown to protect DNA against degradation by colicin E7. Conclusions Our data infer that nonspecific DNA binding of the Imu3 immunity protein, prevents suicide of E. coli producing the genotoxin Usp. PMID:24472116

  8. Redox-sensitive protein phosphatase activity regulates the phosphorylation state of p38 protein kinase in primary astrocyte culture.

    PubMed

    Robinson, K A; Stewart, C A; Pye, Q N; Nguyen, X; Kenney, L; Salzman, S; Floyd, R A; Hensley, K

    1999-03-15

    Reactive oxygen species (ROS) have been implicated as second messengers that activate protein kinase cascades, although the means by which ROS regulate signal transduction remains unclear. In the present study, we show that interleukin 1beta (IL1beta), H2O2, and sorbitol-induced hyperosmolarity mediate a 5- to 10-fold increase in phosphorylation (activation) of the p38 protein kinase in rat primary glial cells as measured by analyses of Western blots using an antibody directed against the dually phosphorylated (active) p38. Additionally, IL1beta was found to elicit H2O2 synthesis in these cells. Concurrent with p38 phosphorylation, all three stimulation paradigms caused an inhibition of protein phosphatase activity. Phenyl-tert-butyl nitrone (PBN), a nitrone-based free radical trap and N-acetyl-cysteine (NAC), a thiol reducing agent, were examined for their effects on the phosphorylation of p38 as well as phosphatase activity. Pretreatment of cells with either PBN or NAC at 1.0 mM suppressed IL1beta H2O2, and sorbitol-mediated activation of p38 and significantly increased phosphatase activity. These data suggest that ROS, particularly H2O2, are used as second messenger substances that activate p38 in part via the transient inactivation of regulatory protein phosphatases.

  9. Evolutionary Conservation of a GPCR-Independent Mechanism of Trimeric G Protein Activation.

    PubMed

    Coleman, Brantley D; Marivin, Arthur; Parag-Sharma, Kshitij; DiGiacomo, Vincent; Kim, Seongseop; Pepper, Judy S; Casler, Jason; Nguyen, Lien T; Koelle, Michael R; Garcia-Marcos, Mikel

    2016-03-01

    Trimeric G protein signaling is a fundamental mechanism of cellular communication in eukaryotes. The core of this mechanism consists of activation of G proteins by the guanine-nucleotide exchange factor (GEF) activity of G protein coupled receptors. However, the duration and amplitude of G protein-mediated signaling are controlled by a complex network of accessory proteins that appeared and diversified during evolution. Among them, nonreceptor proteins with GEF activity are the least characterized. We recently found that proteins of the ccdc88 family possess a Gα-binding and activating (GBA) motif that confers GEF activity and regulates mammalian cell behavior. A sequence similarity-based search revealed that ccdc88 genes are highly conserved across metazoa but the GBA motif is absent in most invertebrates. This prompted us to investigate whether the GBA motif is present in other nonreceptor proteins in invertebrates. An unbiased bioinformatics search in Caenorhabditis elegans identified GBAS-1 (GBA and SPK domain containing-1) as a GBA motif-containing protein with homologs only in closely related worm species. We demonstrate that GBAS-1 has GEF activity for the nematode G protein GOA-1 and that the two proteins are coexpressed in many cells of living worms. Furthermore, we show that GBAS-1 can activate mammalian Gα-subunits and provide structural insights into the evolutionarily conserved determinants of the GBA-G protein interface. These results demonstrate that the GBA motif is a functional GEF module conserved among highly divergent proteins across evolution, indicating that the GBA-Gα binding mode is strongly constrained under selective pressure to mediate receptor-independent G protein activation in metazoans. PMID:26659249

  10. Evolutionary Conservation of a GPCR-Independent Mechanism of Trimeric G Protein Activation

    PubMed Central

    Coleman, Brantley D.; Marivin, Arthur; Parag-Sharma, Kshitij; DiGiacomo, Vincent; Kim, Seongseop; Pepper, Judy S.; Casler, Jason; Nguyen, Lien T.; Koelle, Michael R.; Garcia-Marcos, Mikel

    2016-01-01

    Trimeric G protein signaling is a fundamental mechanism of cellular communication in eukaryotes. The core of this mechanism consists of activation of G proteins by the guanine-nucleotide exchange factor (GEF) activity of G protein coupled receptors. However, the duration and amplitude of G protein-mediated signaling are controlled by a complex network of accessory proteins that appeared and diversified during evolution. Among them, nonreceptor proteins with GEF activity are the least characterized. We recently found that proteins of the ccdc88 family possess a Gα-binding and activating (GBA) motif that confers GEF activity and regulates mammalian cell behavior. A sequence similarity-based search revealed that ccdc88 genes are highly conserved across metazoa but the GBA motif is absent in most invertebrates. This prompted us to investigate whether the GBA motif is present in other nonreceptor proteins in invertebrates. An unbiased bioinformatics search in Caenorhabditis elegans identified GBAS-1 (GBA and SPK domain containing-1) as a GBA motif-containing protein with homologs only in closely related worm species. We demonstrate that GBAS-1 has GEF activity for the nematode G protein GOA-1 and that the two proteins are coexpressed in many cells of living worms. Furthermore, we show that GBAS-1 can activate mammalian Gα-subunits and provide structural insights into the evolutionarily conserved determinants of the GBA–G protein interface. These results demonstrate that the GBA motif is a functional GEF module conserved among highly divergent proteins across evolution, indicating that the GBA-Gα binding mode is strongly constrained under selective pressure to mediate receptor-independent G protein activation in metazoans. PMID:26659249

  11. Eukaryotic G Protein Signaling Evolved to Require G Protein–Coupled Receptors for Activation

    PubMed Central

    Bradford, William; Buckholz, Adam; Morton, John; Price, Collin; Jones, Alan M.; Urano, Daisuke

    2016-01-01

    Although bioinformatic analysis of the increasing numbers of diverse genome sequences and amount of functional data has provided insight into the evolution of signaling networks, bioinformatics approaches have limited application for understanding the evolution of highly divergent protein families. We used biochemical analyses to determine the in vitro properties of selected divergent components of the heterotrimeric guanine nucleotide–binding protein (G protein) signaling network to investigate signaling network evolution. In animals, G proteins are activated by cell-surface seven-transmembrane (7TM) receptors, which are named G protein–coupled receptors (GPCRs) and function as guanine nucleotide exchange factors (GEFs). In contrast, the plant G protein is intrinsically active, and a 7TM protein terminates G protein activity by functioning as a guanosine triphosphatase–activating protein (GAP). We showed that ancient regulation of the G protein active state is GPCR-independent and “self-activating,” a property that is maintained in Bikonts, one of the two fundamental evolutionary clades containing eukaryotes, whereas G proteins of the other clade, the Unikonts, evolved from being GEF-independent to being GEF-dependent. Self-activating G proteins near the base of the Eukaryota are controlled by 7TM-GAPs, suggesting that the ancestral regulator of G protein activation was a GAP-functioning receptor, not a GEF-functioning GPCR. Our findings indicate that the GPCR paradigm describes a recently evolved network architecture found in a relatively small group of Eukaryota and suggest that the evolution of signaling network architecture is constrained by the availability of molecules that control the activation state of nexus proteins. PMID:23695163

  12. Intracellular protein delivery activity of peptides derived from insulin-like growth factor binding proteins 3 and 5

    SciTech Connect

    Goda, Natsuko; Tenno, Takeshi; Inomata, Kosuke; Shirakawa, Masahiro; Tanaka, Toshiki; Hiroaki, Hidekazu

    2008-08-01

    Insulin-like growth factor binding proteins (IGFBPs) have various IGF-independent cellular activities, including receptor-independent cellular uptake followed by transcriptional regulation, although mechanisms of cellular entry remain unclear. Herein, we focused on their receptor-independent cellular entry mechanism in terms of protein transduction domain (PTD) activity, which is an emerging technique useful for clinical applications. The peptides of 18 amino acid residues derived from IGFBP-3 and IGFBP-5, which involve heparin-binding regions, mediated cellular delivery of an exogenous protein into NIH3T3 and HeLa cells. Relative protein delivery activities of IGFBP-3/5-derived peptides were approximately 20-150% compared to that of the HIV-Tat peptide, a potent PTD. Heparin inhibited the uptake of the fusion proteins with IGFBP-3 and IGFBP-5, indicating that the delivery pathway is heparin-dependent endocytosis, similar to that of HIV-Tat. The delivery of GST fused to HIV-Tat was competed by either IGFBP-3 or IGFBP-5-derived synthetic peptides. Therefore, the entry pathways of the three PTDs are shared. Our data has shown a new approach for designing protein delivery systems using IGFBP-3/5 derived peptides based on the molecular mechanisms of IGF-independent activities of IGFBPs.

  13. Visna virus Tat protein: a potent transcription factor with both activator and suppressor domains.

    PubMed Central

    Carruth, L M; Hardwick, J M; Morse, B A; Clements, J E

    1994-01-01

    Visna virus is a pathogenic lentivirus of sheep tat is distantly related to the primate lentiviruses, including human immunodeficiency virus type 1. The visna virus genome encodes a small regulatory protein, Tat, which is necessary for efficient viral replication and enhanced viral transcription. To investigate the mechanism of action of the visna Tat protein and to localize the protein domain(s) responsible for transcriptional activation, chimeric proteins containing visna virus Tat sequences fused to the DNA binding domain of the yeast transactivation factor GAL4 (residues 1 to 147) were made. The GAL4-Tat fusion proteins were transfected into cells and tested for the ability to activate the adenovirus E1b promoter via upstream GAL4 DNA binding sites. Full-length GAL4-Tat fusion proteins were weak transactivators in this system, giving only a two- to fourfold increase in transcription in several cell types, including HeLa and sheep choroid plexus cells. In contrast, fusion of the N-terminal region of the Tat protein to GAL4 revealed a potent activation domain. Amino acids 13 to 38 appeared to be the most critical for activation. No other region of the protein showed any activation in the GAL4 system. This N-terminal region of the visna virus Tat protein has a large number of acidic and hydrophobic residues, suggesting that Tat has an acidic activation domain common to many transcriptional transactivators. Mutations in hydrophobic and bulky aromatic residues dramatically reduced the activity of the chimeric protein. Competition experiments suggest that mechanism of the visna virus Tat activation domain may closely resemble that of the herpesvirus activator VP16 and human immunodeficiency virus Tat, a related lentivirus activator, since both significantly reduce the level of visna virus Tat activation. Finally, a domain between residues 39 and 53 was identified in the Tat protein that, in the GAL4 system, negatively regulates activation by Tat. Images PMID:8083955

  14. Bioinorganic Chemical Modeling of Dioxygen-Activating Copper Proteins.

    ERIC Educational Resources Information Center

    Karlin, Kenneth D.; Gultneh, Yilma

    1985-01-01

    Discusses studies done in modeling the copper centers in the proteins hemocyanin (a dioxygen carrier), tyrosinase, and dopamine beta-hydroxylase. Copper proteins, model approach in copper bioinorganic chemistry, characterization of reversible oxygen carriers and dioxygen-metal complexes, a copper mono-oxygenase model reaction, and other topics are…

  15. Tryptase Activation of Immortalized Human Urothelial Cell Mitogen-Activated Protein Kinase

    PubMed Central

    Marentette, John O.; Hauser, Paul J.; Hurst, Robert E.; Klumpp, David J.; Rickard, Alice; McHowat, Jane

    2013-01-01

    The pathogenesis of interstitial cystitis/painful bladder syndrome (IC/PBS) is multifactorial, but likely involves urothelial cell dysfunction and mast cell accumulation in the bladder wall. Activated mast cells in the bladder wall release several inflammatory mediators, including histamine and tryptase. We determined whether mitogen-activated protein (MAP) kinases are activated in response to tryptase stimulation of urothelial cells derived from human normal and IC/PBS bladders. Tryptase stimulation of normal urothelial cells resulted in a 2.5-fold increase in extracellular signal regulated kinase 1/2 (ERK 1/2). A 5.5-fold increase in ERK 1/2 activity was observed in urothelial cells isolated from IC/PBS bladders. No significant change in p38 MAP kinase was observed in tryptase-stimulated normal urothelial cells but a 2.5-fold increase was observed in cells isolated from IC/PBS bladders. Inhibition of ERK 1/2 with PD98059 or inhibition of p38 MAP kinase with SB203580 did not block tryptase-stimulated iPLA2 activation. Incubation with the membrane phospholipid-derived PLA2 hydrolysis product lysoplasmenylcholine increased ERK 1/2 activity, suggesting the iPLA2 activation is upstream of ERK 1/2. Real time measurements of impedance to evaluate wound healing of cell cultures indicated increased healing rates in normal and IC/PBS urothelial cells in the presence of tryptase, with inhibition of ERK 1/2 significantly decreasing the wound healing rate of IC/PBS urothelium. We conclude that activation of ERK 1/2 in response to tryptase stimulation may facilitate wound healing or cell motility in areas of inflammation in the bladder associated with IC/PBS. PMID:23922867

  16. Structure-activity relationship of synthetic branched-chain distearoylglycerol (distearin) as protein kinase C activators

    SciTech Connect

    Zhou, Qingzhong; Raynor, R.L.; Wood, M.G. Jr.; Menger, F.M.; Kuo, J.F. )

    1988-09-20

    Several representative branched-chain analogues of distearin (DS) were synthesized and tested for their abilities to activate protein kinase C (PKC) and to compete for the binding of ({sup 3}H)phorbol 12,13-dibutyrate (PDBu) to the enzyme. Substitutions of stearoyl moieties at sn-1 and sn-2 with 8-methylstearate decreased activities on these parameters, relative to those of the parental diacylglycerol DS, a weak PKC activator. Substitutions with 8-butyl, 4-butyl, or 8-phenyl derivatives, on the other hand, increased activities of the resulting analogues to levels comparable to those seen for diolein (DO), a diacylglycerol prototype shown to be a potent PKC activator. Kinetic analysis indicated that 8-methyldistearin (8-MeDS) acted by decreasing, whereas 8-butyldistearin (8-BuDS) and 8-phenyldistearin (8-PhDS) acted by increasing, the affinities of PKC for phosphatidylserine (PS, a phospholipid cofactor) and Ca{sup 2+} compared to the values seen in the absence or presence of DS. The stimulatory effect of 8-BuDS and 8-PhDS on PKC, as DO, was additive to that of 1,2-(8-butyl)distearoylphosphatidylcholine (1,2(8-Bu)DSPC) and, moreover, they abolished the marked inhibition of the enzyme activity caused by high concentrations of 1,2(8-Bu)DSPC. The present findings demonstrated a structure-activity relationship of the branched-chain DS analogues in the regulation of PKC, perhaps related to their abilities to specifically modify interactions of PKC with PS and/or Ca{sup 2+} critically involved in enzyme activation/inactivation.

  17. Glucagon receptor activates extracellular signal-regulated protein kinase 1/2 via cAMP-dependent protein kinase

    PubMed Central

    Jiang, Youwei; Cypess, Aaron M.; Muse, Evan D.; Wu, Cui-Rong; Unson, Cecilia G.; Merrifield, R. B.; Sakmar, Thomas P.

    2001-01-01

    We prepared a stable cell line expressing the glucagon receptor to characterize the effect of Gs-coupled receptor stimulation on extracellular signal-regulated protein kinase 1/2 (ERK1/2) activity. Glucagon treatment of the cell line caused a dose-dependent increase in cAMP concentration, activation of cAMP-dependent protein kinase (PKA), and transient release of intracellular calcium. Glucagon treatment also caused rapid dose-dependent phosphorylation and activation of mitogen-activated protein kinase kinase/ERK kinase (MEK1/2) and ERK1/2. Inhibition of either PKA or MEK1/2 blocked ERK1/2 activation by glucagon. However, no significant activation of several upstream activators of MEK, including Ras, Rap1, and Raf, was observed in response to glucagon treatment. In addition, chelation of intracellular calcium reduced glucagon-mediated ERK1/2 activation. In transient transfection experiments, glucagon receptor mutants that bound glucagon but failed to increase intracellular cAMP and calcium concentrations showed no glucagon-stimulated ERK1/2 phosphorylation. We conclude that glucagon-induced MEK1/2 and ERK1/2 activation is mediated by PKA and that an increase in intracellular calcium concentration is required for maximal ERK activation. PMID:11517300

  18. Regulation of mitogen-activated protein kinase 3/1 activity during meiosis resumption in mammals

    PubMed Central

    PROCHAZKA, Radek; BLAHA, Milan

    2015-01-01

    In vivo, resumption of oocyte meiosis occurs in large ovarian follicles after the preovulatory surge of luteinizing hormone (LH). The LH surge leads to the activation of a broad signaling network in mural granulosa cells equipped with LH receptors. The signals generated in the mural granulosa cells are further augmented by locally produced peptides or steroids and transferred to the cumulus cell compartment and the oocyte itself. Over the last decade, essential progress has been made in the identification of molecular events associated with the final maturation and ovulation of mammalian oocytes. All new evidence argues for a multiple roles of mitogen-activated protein kinase 3/1 (MAPK3/1) in the gonadotropin-induced ovulation processes. However, the knowledge of gonadotropin-induced signaling pathways leading to MAPK3/1 activation in follicular cells seems limited. To date, only the LH-induced transactivation of the epidermal growth factor receptor/MAPK3/1 pathway has been described in granulosa/cumulus cells even though other mechanisms of MAPK3/1 activation have been detected in other types of cells. In this review, we aimed to summarize recent advances in the elucidation of gonadotropin-induced mechanisms leading to the activation of MAPK3/1 in preovulatory follicles and cultured cumulus-oocyte complexes and to point out a specific role of this kinase in the processes accompanying final maturation of the mammalian oocyte. PMID:26688146

  19. A Simple and Effective Protein Folding Activity Suitable for Large Lectures

    ERIC Educational Resources Information Center

    White, Brian

    2006-01-01

    This article describes a simple and inexpensive hands-on simulation of protein folding suitable for use in large lecture classes. This activity uses a minimum of parts, tools, and skill to simulate some of the fundamental principles of protein folding. The major concepts targeted are that proteins begin as linear polypeptides and fold to…

  20. Astragaloside II triggers T cell activation through regulation of CD45 protein tyrosine phosphatase activity

    PubMed Central

    Wan, Chun-ping; Gao, Li-xin; Hou, Li-fei; Yang, Xiao-qian; He, Pei-lan; Yang, Yi-fu; Tang, Wei; Yue, Jian-min; Li, Jia; Zuo, Jian-ping

    2013-01-01

    Aim: To investigate the immunomodulating activity of astragalosides, the active compounds from a traditional tonic herb Astragalus membranaceus Bge, and to explore the molecular mechanisms underlying the actions, focusing on CD45 protein tyrosine phosphatase (CD45 PTPase), which plays a critical role in T lymphocyte activation. Methods: Primary splenocytes and T cells were prepared from mice. CD45 PTPase activity was assessed using a colorimetric assay. Cell proliferation was measured using a [3H]-thymidine incorporation assay. Cytokine proteins and mRNAs were examined with ELISA and RT-PCR, respectively. Activation markers, including CD25 and CD69, were analyzed using flow cytometry. Activation of LCK (Tyr505) was detected using Western blot analysis. Mice were injected with the immunosuppressant cyclophosphamide (CTX, 80 mg/kg), and administered astragaloside II (50 mg/kg). Results: Astragaloside I, II, III, and IV concentration-dependently increased the CD45-mediated of pNPP/OMFP hydrolysis with the EC50 values ranged from 3.33 to 10.42 μg/mL. Astragaloside II (10 and 30 nmol/L) significantly enhanced the proliferation of primary splenocytes induced by ConA, alloantigen or anti-CD3. Astragaloside II (30 nmol/L) significantly increased IL-2 and IFN-γ secretion, upregulated the mRNA levels of IFN-γ and T-bet in primary splenocytes, and promoted CD25 and CD69 expression on primary CD4+ T cells upon TCR stimulation. Furthermore, astragaloside II (100 nmol/L) promoted CD45-mediated dephosphorylation of LCK (Tyr505) in primary T cells, which could be blocked by a specific CD45 PTPase inhibitor. In CTX-induced immunosuppressed mice, oral administration of astragaloside II restored the proliferation of splenic T cells and the production of IFN-γ and IL-2. However, astragaloside II had no apparent effects on B cell proliferation. Conclusion: Astragaloside II enhances T cell activation by regulating the activity of CD45 PTPase, which may explain why Astragalus

  1. Protein Synthesis Inhibition Activity by Strawberry Tissue Protein Extracts during Plant Life Cycle and under Biotic and Abiotic Stresses

    PubMed Central

    Polito, Letizia; Bortolotti, Massimo; Mercatelli, Daniele; Mancuso, Rossella; Baruzzi, Gianluca; Faedi, Walther; Bolognesi, Andrea

    2013-01-01

    Ribosome-inactivating proteins (RIPs), enzymes that are widely distributed in the plant kingdom, inhibit protein synthesis by depurinating rRNA and many other polynucleotidic substrates. Although RIPs show antiviral, antifungal, and insecticidal activities, their biological and physiological roles are not completely understood. Additionally, it has been described that RIP expression is augmented under stressful conditions. In this study, we evaluated protein synthesis inhibition activity in partially purified basic proteins (hereafter referred to as RIP activity) from tissue extracts of Fragaria × ananassa (strawberry) cultivars with low (Dora) and high (Record) tolerance to root pathogens and fructification stress. Association between the presence of RIP activity and the crop management (organic or integrated soil), growth stage (quiescence, flowering, and fructification), and exogenous stress (drought) were investigated. RIP activity was found in every tissue tested (roots, rhizomes, leaves, buds, flowers, and fruits) and under each tested condition. However, significant differences in RIP distribution were observed depending on the soil and growth stage, and an increase in RIP activity was found in the leaves of drought-stressed plants. These results suggest that RIP expression and activity could represent a response mechanism against biotic and abiotic stresses and could be a useful tool in selecting stress-resistant strawberry genotypes. PMID:23892598

  2. Mechanistic pathways and biological roles for receptor-independent activators of G-protein signaling.

    PubMed

    Blumer, Joe B; Smrcka, Alan V; Lanier, Stephen M

    2007-03-01

    Signal processing via heterotrimeric G-proteins in response to cell surface receptors is a central and much investigated aspect of how cells integrate cellular stimuli to produce coordinated biological responses. The system is a target of numerous therapeutic agents and plays an important role in adaptive processes of organs; aberrant processing of signals through these transducing systems is a component of various disease states. In addition to G-protein coupled receptor (GPCR)-mediated activation of G-protein signaling, nature has evolved creative ways to manipulate and utilize the Galphabetagamma heterotrimer or Galpha and Gbetagamma subunits independent of the cell surface receptor stimuli. In such situations, the G-protein subunits (Galpha and Gbetagamma) may actually be complexed with alternative binding partners independent of the typical heterotrimeric Galphabetagamma. Such regulatory accessory proteins include the family of regulator of G-protein signaling (RGS) proteins that accelerate the GTPase activity of Galpha and various entities that influence nucleotide binding properties and/or subunit interaction. The latter group of proteins includes receptor-independent activators of G-protein signaling (AGS) proteins that play surprising roles in signal processing. This review provides an overview of our current knowledge regarding AGS proteins. AGS proteins are indicative of a growing number of accessory proteins that influence signal propagation, facilitate cross talk between various types of signaling pathways, and provide a platform for diverse functions of both the heterotrimeric Galphabetagamma and the individual Galpha and Gbetagamma subunits.

  3. Relationship between protein C antigen and anticoagulant activity during oral anticoagulation and in selected disease states.

    PubMed Central

    Vigano D'Angelo, S; Comp, P C; Esmon, C T; D'Angelo, A

    1986-01-01

    Protein C is a natural vitamin K-dependent plasma anticoagulant, deficiencies of which have been found in patients with recurrent thrombosis and warfarin-induced skin necrosis. To appreciate more fully the role of protein C in disease states and during oral anticoagulation, a new functional assay for protein C involving adsorption of plasma protein C on a Ca+2-dependent monoclonal antibody, elution, quantitative activation, and assessment of plasma anticoagulant activity, has been developed. When oral anticoagulation is initiated, the anticoagulant activity of protein C decreases to a greater extent than either the amidolytic or immunologic levels. During stabilized warfarin treatment, there is no correlation between either amidolytic or antigenic levels and the functional protein C activity, suggesting that measurement of protein C anticoagulant activity may be necessary to reflect adequately the anticoagulant protection afforded by this protein. In contrast, there was a strong correlation between anticoagulant and amidolytic and immunologic levels in liver failure and disseminated intravascular coagulation. Two patients with thromboembolic disease have been identified who exhibit a marked decrease in anticoagulant activity, but who have normal immunologic and amidolytic levels. Thus, this assay permits assessment of protein C in individuals who have received anticoagulant treatment and identification of a new class of protein C-deficient individuals. PMID:3511097

  4. Thymic Stromal Lymphopoietin Promotes Fibrosis and Activates Mitogen-Activated Protein Kinases in MRC-5 Cells

    PubMed Central

    Li, Li; Tang, Su; Tang, Xiaodong

    2016-01-01

    Background Acute lung injury (ALI) is a life-threatening hypoxemic respiratory disorder with high incidence and mortality. ALI usually manifests as widespread inflammation and lung fibrosis with the accumulation of pro-inflammatory and pro-fibrotic factors and collagen. Thymic stromal lymphopoietin (TSLP) has a significant role in regulation of inflammation but little is known about its roles in lung fibrosis or ALI. This study aimed to define the role and possible regulatory mechanism of TSLP in lung fibrosis. Material/Methods We cultured human lung fibroblast MRC-5 cells and overexpressed or inhibited TSLP by the vector or small interfering RNA transfection. Then, the pro-fibrotic factors skeletal muscle actin alpha (α-SMA) and collagen I, and the 4 mitogen-activated protein kinases (MAPKs) – MAPK7, p38, extracellular signal-regulated kinase 1 (ERK1), and c-Jun N-terminal kinase 1 (JNK1) – were detected by Western blot. Results Results showed that TSLP promoted the production of α-SMA and collagen I (P<0.001), suggesting that it can accelerate MRC-5 cell fibrosis. It also activated the expression of MAPK7, p-p38, p-ERK1, and p-JNK1, but the total MAPK7, p-38, ERK1, and JNK1 protein levels were mostly unchanged, indicating the activated MAPK pathways that might contribute to the promotion of cell fibrosis. Conclusions This study shows the pro-fibrotic role of TSLP in MRC-5 cells, suggesting TSLP is a potential therapeutic target for treating lung fibrosis in ALI. It possibly functions via activating MAPKs. These findings add to our understanding of the mechanism of fibrosis. PMID:27385084

  5. CDK5 activator protein p25 preferentially binds and activates GSK3β.

    PubMed

    Chow, Hei-Man; Guo, Dong; Zhou, Jie-Chao; Zhang, Guan-Yun; Li, Hui-Fang; Herrup, Karl; Zhang, Jie

    2014-11-11

    Glycogen synthase kinase 3β (GSK3β) and cyclin-dependent kinase 5 (CDK5) are tau kinases and have been proposed to contribute to the pathogenesis of Alzheimer's disease. The 3D structures of these kinases are remarkably similar, which led us to hypothesize that both might be capable of binding cyclin proteins--the activating cofactors of all CDKs. CDK5 is normally activated by the cyclin-like proteins p35 and p39. By contrast, we show that GSK3β does not bind to p35 but unexpectedly binds to p25, the calpain cleavage product of p35. Indeed, overexpressed GSK3β outcompetes CDK5 for p25, whereas CDK5 is the preferred p35 partner. FRET analysis reveals nanometer apposition of GSK3β:p25 in cell soma as well as in synaptic regions. Interaction with p25 also alters GSK3β substrate specificity. The GSK3β:p25 interaction leads to enhanced phosphorylation of tau, but decreased phosphorylation of β-catenin. A partial explanation for this situation comes from in silico modeling, which predicts that the docking site for p25 on GSK3β is the AXIN-binding domain; because of this, p25 inhibits the formation of the GSK3β/AXIN/APC destruction complex, thus preventing GSK3β from binding to and phosphorylating β-catenin. Coexpression of GSK3β and p25 in cultured neurons results in a neurodegeneration phenotype that exceeds that observed with CDK5 and p25. When p25 is transfected alone, the resulting neuronal damage is blocked more effectively with a specific siRNA against Gsk3β than with one against Cdk5. We propose that the effects of p25, although normally attributed to activate CDK5, may be mediated in part by elevated GSK3β activity.

  6. Regulation of Protease-activated Receptor 1 Signaling by the Adaptor Protein Complex 2 and R4 Subfamily of Regulator of G Protein Signaling Proteins*

    PubMed Central

    Chen, Buxin; Siderovski, David P.; Neubig, Richard R.; Lawson, Mark A.; Trejo, JoAnn

    2014-01-01

    The G protein-coupled protease-activated receptor 1 (PAR1) is irreversibly proteolytically activated by thrombin. Hence, the precise regulation of PAR1 signaling is important for proper cellular responses. In addition to desensitization, internalization and lysosomal sorting of activated PAR1 are critical for the termination of signaling. Unlike most G protein-coupled receptors, PAR1 internalization is mediated by the clathrin adaptor protein complex 2 (AP-2) and epsin-1, rather than β-arrestins. However, the function of AP-2 and epsin-1 in the regulation of PAR1 signaling is not known. Here, we report that AP-2, and not epsin-1, regulates activated PAR1-stimulated phosphoinositide hydrolysis via two different mechanisms that involve, in part, a subset of R4 subfamily of “regulator of G protein signaling” (RGS) proteins. A significantly greater increase in activated PAR1 signaling was observed in cells depleted of AP-2 using siRNA or in cells expressing a PAR1 420AKKAA424 mutant with defective AP-2 binding. This effect was attributed to AP-2 modulation of PAR1 surface expression and efficiency of G protein coupling. We further found that ectopic expression of R4 subfamily members RGS2, RGS3, RGS4, and RGS5 reduced activated PAR1 wild-type signaling, whereas signaling by the PAR1 AKKAA mutant was minimally affected. Intriguingly, siRNA-mediated depletion analysis revealed a function for RGS5 in the regulation of signaling by the PAR1 wild type but not the AKKAA mutant. Moreover, activation of the PAR1 wild type, and not the AKKAA mutant, induced Gαq association with RGS3 via an AP-2-dependent mechanism. Thus, AP-2 regulates activated PAR1 signaling by altering receptor surface expression and through recruitment of RGS proteins. PMID:24297163

  7. Regulation of protease-activated receptor 1 signaling by the adaptor protein complex 2 and R4 subfamily of regulator of G protein signaling proteins.

    PubMed

    Chen, Buxin; Siderovski, David P; Neubig, Richard R; Lawson, Mark A; Trejo, Joann

    2014-01-17

    The G protein-coupled protease-activated receptor 1 (PAR1) is irreversibly proteolytically activated by thrombin. Hence, the precise regulation of PAR1 signaling is important for proper cellular responses. In addition to desensitization, internalization and lysosomal sorting of activated PAR1 are critical for the termination of signaling. Unlike most G protein-coupled receptors, PAR1 internalization is mediated by the clathrin adaptor protein complex 2 (AP-2) and epsin-1, rather than β-arrestins. However, the function of AP-2 and epsin-1 in the regulation of PAR1 signaling is not known. Here, we report that AP-2, and not epsin-1, regulates activated PAR1-stimulated phosphoinositide hydrolysis via two different mechanisms that involve, in part, a subset of R4 subfamily of "regulator of G protein signaling" (RGS) proteins. A significantly greater increase in activated PAR1 signaling was observed in cells depleted of AP-2 using siRNA or in cells expressing a PAR1 (420)AKKAA(424) mutant with defective AP-2 binding. This effect was attributed to AP-2 modulation of PAR1 surface expression and efficiency of G protein coupling. We further found that ectopic expression of R4 subfamily members RGS2, RGS3, RGS4, and RGS5 reduced activated PAR1 wild-type signaling, whereas signaling by the PAR1 AKKAA mutant was minimally affected. Intriguingly, siRNA-mediated depletion analysis revealed a function for RGS5 in the regulation of signaling by the PAR1 wild type but not the AKKAA mutant. Moreover, activation of the PAR1 wild type, and not the AKKAA mutant, induced Gαq association with RGS3 via an AP-2-dependent mechanism. Thus, AP-2 regulates activated PAR1 signaling by altering receptor surface expression and through recruitment of RGS proteins. PMID:24297163

  8. Double-Stranded RNA-Induced Activation of Activating Protein-1 Promoter Is Differentially Regulated by the Non-structural Protein 1 of Avian Influenza A Viruses

    PubMed Central

    Zohari, Siamak; Belák, Sándor; Berg, Mikael

    2012-01-01

    Abstract Non-structural protein 1 (NS1) of influenza A viruses is a multifunctional protein that antagonizes the host immune response by interfering with several host signaling pathways. Based on putative amino acid sequences, NS1 proteins are categorized into two gene pools, allele A and allele B. Here we identified that allele A NS1 proteins of H6N8 and H4N6 are able to inhibit double-stranded RNA (dsRNA)-induced activating protein-1 (AP-1) promoter in cultured cell lines (human A549 and mink lung cells). Allele B NS1 proteins from corresponding subtypes of influenza A viruses are weak in this inhibition, despite significant levels of expression of each NS1 protein in human A549 cells. Furthermore, the capability to inhibit AP-1 promoter was mapped in the effector domain, since RNA binding domain alone lost its ability to inhibit this promoter activation. Chimeric forms of NS1 protein, composed of either RNA binding domain of allele A or B and effector domain of allele A or B, showed comparable inhibition to that of their wild-type NS1 proteins, or to the effector domain of corresponding NS1 proteins. Both alleles A and B NS1 proteins of H6N8 and H4N6 were expressed to significant levels, and were localized predominantly in the nucleus of human A549 cells. These results underscore the importance of the effector domain in inhibiting AP-1 promoter activation, and the biological function of the effector domain in stabilizing the RNA binding domain. Further, we revealed the versatile nature of NS1 in inhibiting the AP-1 transcription factor, in a manner dependent on allele type. Comprehensive studies, focusing on the molecular mechanisms behind this differential inhibition, may facilitate exploration of the zoonotic and pathogenic potential of influenza A viruses. PMID:22239235

  9. Beta 2 integrin-dependent protein tyrosine phosphorylation and activation of the FGR protein tyrosine kinase in human neutrophils

    PubMed Central

    1994-01-01

    Stimulation of adherent human neutrophils (PMN) with tumor necrosis factor (TNF) triggers protein tyrosine phosphorylation (Fuortes, M., W. W. Jin, and C. Nathan. 1993. J. Cell Biol. 120:777-784). We investigated the dependence of this response on beta 2 integrins by using PMN isolated from a leukocyte adhesion deficiency (LAD) patient, which do not express beta 2 integrins, and by plating PMN on surface bound anti-beta 2 (CD18) antibodies. Protein tyrosine phosphorylation increased in PMN plated on fibrinogen and this phosphorylation was enhanced by TNF. Triggering of protein tyrosine phosphorylation did not occur in LAD PMN plated on fibrinogen either in the absence or the presence of TNF. Surface bound anti-CD18, but not isotype-matched anti- Class I major histocompatibility complex (MHC) antigens, antibodies triggered tyrosine phosphorylation in normal, but not in LAD PMN. As the major tyrosine phosphorylated proteins we found in our assay conditions migrated with an apparent molecular mass of 56-60 kD, we investigated whether beta 2 integrins are implicated in activation of members of the src family of intracellular protein-tyrosine kinases. We found that the fgr protein-tyrosine kinase (p58fgr) activity, and its extent of phosphorylation in tyrosine, in PMN adherent to fibrinogen, was enhanced by TNF. Activation of p58fgr in response to TNF was evident within 10 min of treatment and increased with times up to 30 min. Also other activators of beta 2 integrins such as phorbol-12- myristate 13-acetate (PMA), and formyl methionyl-leucyl-phenylalanine (FMLP), induced activation of p58fgr kinase activity. Activation of p58fgr kinase activity, and phosphorylation in tyrosine, did not occur in PMN of a LAD patient in response to TNF. Soluble anti-CD18, but not anti-Class I MHC antigens, antibodies inhibited activation of p58fgr kinase activity in PMN adherent to fibrinogen in response to TNF, PMA, and FMLP. These findings demonstrate that, in PMN, beta 2 integrins

  10. Modulating protein activity using tethered ligands with mutually exclusive binding sites

    PubMed Central

    Schena, Alberto; Griss, Rudolf; Johnsson, Kai

    2015-01-01

    The possibility to design proteins whose activities can be switched on and off by unrelated effector molecules would enable applications in various research areas, ranging from biosensing to synthetic biology. We describe here a general method to modulate the activity of a protein in response to the concentration of a specific effector. The approach is based on synthetic ligands that possess two mutually exclusive binding sites, one for the protein of interest and one for the effector. Tethering such a ligand to the protein of interest results in an intramolecular ligand–protein interaction that can be disrupted through the presence of the effector. Specifically, we introduce a luciferase controlled by another protein, a human carbonic anhydrase whose activity can be controlled by proteins or small molecules in vitro and on living cells, and novel fluorescent and bioluminescent biosensors. PMID:26198003

  11. Vitamin K dependent protein activity and incident ischemic cardiovascular disease: The multi ethnic study of atherosclerosis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    OBJECTIVE: Vitamin K-dependent proteins (VKDPs), which require post-translational modification to achieve biological activity, seem to contribute to thrombus formation, vascular calcification, and vessel stiffness. Whether VKDP activity is prospectively associated with incident cardiovascular diseas...

  12. Mitogen-activated protein kinase activation in UV-induced signal transduction.

    PubMed

    Bode, Ann M; Dong, Zigang

    2003-01-28

    Experimental evidence supported by epidemiological findings suggests that solar ultraviolet (UV) irradiation is the most important environmental carcinogen leading to the development of skin cancers. Because the ozone layer blocks UVC (wavelength, 180 to 280 nm) exposure, UVA (UVA I, 340 to 400 nm; UVA II, 320 to 340 nm) and UVB (280 to 320 nm) are probably the chief carcinogenic components of sunlight with relevance for human skin cancer. Substantial contributions to the elucidation of the specific signal transduction pathways involved in UV-induced skin carcinogenesis have been made over the past few years, and most evidence suggests that the cellular signaling response is UV wavelength-dependent. The mitogen-activated protein kinase (MAPK) signaling cascades are targets for UV and are important in the regulation of the multitude of UV-induced cellular responses. Experimental studies have used a range of UVA, UVB, UVC, and various combinations in multiple doses, and the observed effects on activation and phosphorylation of MAPKs are varied. This review focuses on the mechanistic data supporting a role for MAPKs in UV-induced skin carcinogenesis. Progress in understanding the mechanisms of UV-induced signal transduction could lead to the use of these protein kinases as specific targets for the prevention and control of skin cancer.

  13. Exchange Protein Activated by cAMP Enhances Long-Term Memory Formation Independent of Protein Kinase A

    ERIC Educational Resources Information Center

    Ma, Nan; Abel, Ted; Hernandez, Pepe J.

    2009-01-01

    It is well established that cAMP signaling within neurons plays a major role in the formation of long-term memories--signaling thought to proceed through protein kinase A (PKA). However, here we show that exchange protein activated by cAMP (Epac) is able to enhance the formation of long-term memory in the hippocampus and appears to do so…

  14. Hypoxia promotes drug resistance in osteosarcoma cells via activating AMP-activated protein kinase (AMPK) signaling

    PubMed Central

    Zhao, Changfu; Zhang, Qiao; Yu, Tao; Sun, Shudong; Wang, Wenjun; Liu, Guangyao

    2016-01-01

    Purpose Drug resistance has been recognized to be a major obstacle to the chemotherapy for osteosarcoma. And the potential importance of hypoxia as a target to reverse drug resistance in osteosarcoma has been indicated, though the mechanism underlining such role is not clarified. The present study aims to investigate the role of hypoxia in the drug resistance in osteosarcoma cells via activating AMP-activated protein kinase (AMPK) signaling. Experimental design We investigated the promotion of the resistance to doxorubicin of osteosarcoma MG-63 and U2-os cells in vitro, and then determined the role of hypoxia-inducible factor-1 (HIF-1)α and HIF-1β, the activation and regulatory role of AMPK in the osteosarcoma U2-os cells which were treated with doxorubicin under hypoxia. Results It was demonstrated that hypoxia significantly reduced the sensitivity of MG-63 and U2-os cells to doxorubicin, indicating an inhibited viability reduction and a reduced apoptosis promotion. And such reduced sensitivity was not associated with HIF-1α, though it was promoted by hypoxia in U2-os cells. Interestingly, the AMPK signaling was significantly promoted by hypoxia in the doxorubicin-treated U2-os cells, with a marked upregulation of phosphorylated AMPK (Thr 172) and phosphorylated acetyl-CoA carboxylase (ACC) (Ser 79), which were sensitive to the AMPK activator, AICAR and the AMPK inhibitor, Compound C. Moreover, the promoted AMPK activity by AICAR or the downregulated AMPK activity by Compound C significantly reduced or promoted the sensitivity of U2-os cells to doxorubicin. Conclusion The present study confirmed the AMPK signaling activation in the doxorubicin-treated osteosarcoma cells, in response to hypoxia, and the chemical upregulation or downregulation of AMPK signaling reduced or increased the chemo-sensitivity of osteosarcoma U2-os cells in vitro. Our study implies that AMPK inhibition might be a effective strategy to sensitize osteocarcoma cells to chemotherapy. PMID

  15. Activation of protein kinase C in permeabilized human neuroblastoma SH-SY5Y cells.

    PubMed

    Larsson, C; Saermark, T; Mau, S; Simonsson, P

    1992-08-01

    The activation of protein kinase C was investigated in digitonin-permeabilized human neuroblastoma SH-SY5Y cells by measuring the phosphorylation of the specific protein kinase C substrate myelin basic protein4-14. The phosphorylation was inhibited by the protein kinase C inhibitory peptide PKC19-36 and was associated to a translocation of the enzyme to the membrane fractions of the SH-SY5Y cells. 1,2-Dioctanoyl-sn-glycerol had no effect on protein kinase C activity unless the calcium concentration was raised to concentrations found in stimulated cells (above 100 nM). Calcium in the absence of other activators did not stimulate protein kinase C. Phorbol 12-myristate 13-acetate was not dependent on calcium for the activation or the translocation of protein kinase C. The induced activation was sustained for 10 min, and thereafter only a small net phosphorylation of the substrate could be detected. Calcium or dioctanoylglycerol, when applied alone, only caused a minor translocation, whereas in combination a marked translocation was observed. Arachidonic acid (10 microM) enhanced protein kinase C activity in the presence of submaximal concentrations of calcium and dioctanoylglycerol. Quinacrine and p-bromophenacyl bromide did not inhibit calcium- and dioctanoylglycerol-induced protein kinase C activity at concentrations which are considered to be sufficient for phospholipase A2 inhibition.

  16. A novel antifungal protein with lysozyme-like activity from seeds of Clitoria ternatea.

    PubMed

    K, Ajesh; K, Sreejith

    2014-06-01

    An antifungal protein with a molecular mass of 14.3 kDa was isolated from the seeds of butterfly pea (Clitoria ternatea) and designated as Ct protein. The antifungal protein was purified using different methods including ammonium sulphate precipitation, ion exchange chromatography on DEAE-cellulose and gel filtration on Sephadex G-50 column. Ct protein formed a single colourless rod-shaped crystal by hanging drop method after 7 days of sample loading. The protein showed lytic activity against Micrococcus luteus and broad-spectrum, fungicidal activity, particularly against the most clinically relevant yeasts, such as Cryptococcus neoformans, Cryptococcus albidus, Cryptococcus laurentii, Candida albicans and Candida parapsilosis. It also exerted an inhibitory activity on mycelial growth in several mould species including Curvularia sp., Alternaria sp., Cladosporium sp., Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Rhizopus sp., and Sclerotium sp. The present study adds to the literature on novel seed proteins with antifungal activity. PMID:24691882

  17. Alteration and modulation of protein activity by varying post-translational modification

    DOEpatents

    Thompson, David N.; Reed, David W.; Thompson, Vicki S.; Lacey, Jeffrey A.; Apel, William A.

    2016-07-12

    Embodiments of the invention include methods of altering the enzymatic activity or solubility of an extremophilic enzyme or post-translationally modifying a protein of interest via using isolated or partially purified glycosyltransferases and/or post-translational modification proteins, extracts of cells comprising glycosyltransferases and/or post-translational modification proteins, and/or in cells comprising one or more glycosyltransferases and/or post-translational modification proteins.

  18. Alteration and modulation of protein activity by varying post-translational modification

    DOEpatents

    Thompson, David N; Reed, David W; Thompson, Vicki S; Lacey, Jeffrey A; Apel, William A

    2015-03-03

    Embodiments of the invention include methods of altering the enzymatic activity or solubility of an extremophilic enzyme or post-translationally modifying a protein of interest via using isolated or partially purified glycosyltransferases and/or post-translational modification proteins, extracts of cells comprising glycosyltransferases and/or post-translational modification proteins, and/or in cells comprising one or more glycosyltransferases and/or post-translational modification proteins.

  19. Activation of p38 Mitogen-Activated Protein Kinase by Clotrimazole Induces Multidrug Resistance-Associated Protein 3 Activation through a Novel Transcriptional Element.

    PubMed

    Sasaki, Takamitsu; Inami, Keita; Numata, Yoshihiro; Funakoshi, Kodai; Yoshida, Midori; Kumagai, Takeshi; Kanno, Shuichi; Matsui, Satomi; Toriyabe, Takayoshi; Yamazoe, Yasushi; Yoshinari, Kouichi; Nagata, Kiyoshi

    2016-10-01

    Multidrug resistance-associated protein 3 (MRP3) is a basolaterally localized transporter in the liver and contributes to the transport of various metabolites such as conjugates of endogenous compounds and drugs from hepatocytes. MRP3 expression in the human liver is low under normal physiologic conditions but is induced by drug treatment. Although several studies have identified a region necessary for the basal transcription of MRP3, no region that responds to drugs has been reported. To identify the xenobiotic-responsive elements of MRP3, we constructed a luciferase reporter plasmid containing the MRP3 5'-flanking region up to -10 kb upstream from the transcription start site. Among typical nuclear receptor ligands, clotrimazole dramatically enhanced MRP3 reporter activity in HepG2 cells, whereas rifampicin had no effect. We then conducted MRP3 reporter assays with deletion or mutation constructs to identify a clotrimazole-responsive element. The element was located approximately -6.8 kb upstream from the MRP3 transcription start site. Overexpression of the pregnane X receptor did not enhance clotrimazole-mediated transcription. We found that clotrimazole was toxic to HepG2 cells and we therefore investigated whether mitogen-activated protein kinase (MAPK) activation is involved in the transactivation of MRP3 by clotrimazole. p38 MAPK inhibitor SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole] suppressed MRP3 mRNA expression induced by clotrimazole, whereas c-Jun N-terminal kinase inhibitor SP600125 (1,9-pyrazoloanthrone) and extracellular signal-regulated kinase inhibitor PD98059 [2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one] did not. Phosphorylated p38 MAPK was detected in HepG2 cells treated with clotrimazole. These results suggest that activation of the p38 MAPK pathway induces the transcriptional activation of MRP3. PMID:27507784

  20. Suppression of Myc oncogenic activity by ribosomal protein haploinsufficiency.

    PubMed

    Barna, Maria; Pusic, Aya; Zollo, Ornella; Costa, Maria; Kondrashov, Nadya; Rego, Eduardo; Rao, Pulivarthi H; Ruggero, Davide

    2008-12-18

    The Myc oncogene regulates the expression of several components of the protein synthetic machinery, including ribosomal proteins, initiation factors of translation, RNA polymerase III and ribosomal DNA. Whether and how increasing the cellular protein synthesis capacity affects the multistep process leading to cancer remains to be addressed. Here we use ribosomal protein heterozygote mice as a genetic tool to restore increased protein synthesis in Emu-Myc/+ transgenic mice to normal levels, and show that the oncogenic potential of Myc in this context is suppressed. Our findings demonstrate that the ability of Myc to increase protein synthesis directly augments cell size and is sufficient to accelerate cell cycle progression independently of known cell cycle targets transcriptionally regulated by Myc. In addition, when protein synthesis is restored to normal levels, Myc-overexpressing precancerous cells are more efficiently eliminated by programmed cell death. Our findings reveal a new mechanism that links increases in general protein synthesis rates downstream of an oncogenic signal to a specific molecular impairment in the modality of translation initiation used to regulate the expression of selective messenger RNAs. We show that an aberrant increase in cap-dependent translation downstream of Myc hyperactivation specifically impairs the translational switch to internal ribosomal entry site (IRES)-dependent translation that is required for accurate mitotic progression. Failure of this translational switch results in reduced mitotic-specific expression of the endogenous IRES-dependent form of Cdk11 (also known as Cdc2l and PITSLRE), which leads to cytokinesis defects and is associated with increased centrosome numbers and genome instability in Emu-Myc/+ mice. When accurate translational control is re-established in Emu-Myc/+ mice, genome instability is suppressed. Our findings demonstrate how perturbations in translational control provide a highly specific outcome

  1. Sasa borealis extract exerts an antidiabetic effect via activation of the AMP-activated protein kinase.

    PubMed

    Nam, Jung Soo; Chung, Hee Jin; Jang, Min Kyung; Jung, In Ah; Park, Seong Ha; Cho, Su In; Jung, Myeong Ho

    2013-02-01

    Leaf of Sasa borealis, a species of bamboo, has been reported to exhibit anti-hyperglycemic effect. However, its antidiabetic mechanism is not fully understood. In this study, we examined whether an extract of S. borealis activates AMP-activated protein kinase (AMPK) and exerts anti-hyperglycemic effects. Treatment with the S. borealis extract increased insulin signaling and phosphorylation of AMPK and stimulated the expression of its downstream targets, including PPARα, ACO, and CPT-1 in C2C12 cells and PPARα in HepG2 cells. However, inhibition of AMPK activation attenuated insulin signaling and prevented the stimulation of AMPK target genes. The S. borealis extract increased glucose uptake in C2C12 cells and suppressed expression of the gluconeogenic gene, PEPCK in HepG2 cells. The extract significantly reduced blood glucose and triglyceride levels in STZ-induced diabetic mice. The extract enhanced AMPK phosphorylation and increased Glut-4 expression in the skeletal muscle of the mice. These findings demonstrated that the S. borealis extract exerts its anti-hyperglycemic effect through activation of AMPK and enhancement of insulin signaling. PMID:23423690

  2. Sasa borealis extract exerts an antidiabetic effect via activation of the AMP-activated protein kinase

    PubMed Central

    Nam, Jung Soo; Chung, Hee Jin; Jang, Min Kyung; Jung, In Ah; Park, Seong Ha; Cho, Su In

    2013-01-01

    Leaf of Sasa borealis, a species of bamboo, has been reported to exhibit anti-hyperglycemic effect. However, its antidiabetic mechanism is not fully understood. In this study, we examined whether an extract of S. borealis activates AMP-activated protein kinase (AMPK) and exerts anti-hyperglycemic effects. Treatment with the S. borealis extract increased insulin signaling and phosphorylation of AMPK and stimulated the expression of its downstream targets, including PPARα, ACO, and CPT-1 in C2C12 cells and PPARα in HepG2 cells. However, inhibition of AMPK activation attenuated insulin signaling and prevented the stimulation of AMPK target genes. The S. borealis extract increased glucose uptake in C2C12 cells and suppressed expression of the gluconeogenic gene, PEPCK in HepG2 cells. The extract significantly reduced blood glucose and triglyceride levels in STZ-induced diabetic mice. The extract enhanced AMPK phosphorylation and increased Glut-4 expression in the skeletal muscle of the mice. These findings demonstrated that the S. borealis extract exerts its anti-hyperglycemic effect through activation of AMPK and enhancement of insulin signaling. PMID:23423690

  3. Why are hyperactive ice-binding-proteins so active?

    NASA Astrophysics Data System (ADS)

    Braslavsky, Ido; Celik, Yeliz; Pertaya, Natalya; Eun Choi, Young; Bar, Maya; Davies, Peter L.

    2008-03-01

    Ice binding proteins (IBPs), also called `antifreeze proteins' or `ice structuring proteins', are a class of proteins that protect organisms from freezing injury. These proteins have many applications in medicine and agriculture, and as a platform for future biotechnology applications. One of the interesting questions in this field focuses on the hyperactivity of some IBPs. Ice binding proteins can be classified in two groups: moderate ones that can depress the freezing point up to ˜1.0 ^oC and hyperactive ones that can depress the freezing point several-fold further even at lower concentrations. It has been suggested that the hyperactivity of IBPs stem from the fact that they block growth out of specific ice surfaces, more specifically the basal planes of ice. Here we show experimental results based on fluorescence microscopy, highlighting the differences between moderate IBPs and hyperactive IBPs. These include direct evidence for basal plane affinity of hyperactive IBPs, the effects of IBPs on growth-melt behavior of ice and the dynamics of their interaction with ice.

  4. Cell signaling through protein kinase C oxidation and activation.

    PubMed

    Cosentino-Gomes, Daniela; Rocco-Machado, Nathália; Meyer-Fernandes, José Roberto

    2012-01-01

    Due to the growing importance of cellular signaling mediated by reactive oxygen species (ROS), proteins that are reversibly modulated by these reactant molecules are of high interest. In this context, protein kinases and phosphatases, which act coordinately in the regulation of signal transduction through the phosphorylation and dephosphorylation of target proteins, have been described to be key elements in ROS-mediated signaling events. The major mechanism by which these proteins may be modified by oxidation involves the presence of key redox-sensitive cysteine residues. Protein kinase C (PKC) is involved in a variety of cellular signaling pathways. These proteins have been shown to contain a unique structural feature that is susceptible to oxidative modification. A large number of scientific studies have highlighted the importance of ROS as a second messenger in numerous cellular processes, including cell proliferation, gene expression, adhesion, differentiation, senescence, and apoptosis. In this context, the goal of this review is to discuss the mechanisms by which PKCs are modulated by ROS and how these processes are involved in the cellular response. PMID:23109817

  5. Conjugation of type I antifreeze protein to polyallylamine increases thermal hysteresis activity.

    PubMed

    Can, Ozge; Holland, Nolan B

    2011-10-19

    Antifreeze proteins (AFPs) are ice binding proteins found in some plants, insects, and Antarctic fish allowing them to survive at subzero temperatures by inhibiting ice crystal growth. The interaction of AFPs with ice crystals results in a difference between the freezing and melting temperatures, termed thermal hysteresis, which is the most common measure of AFP activity. Creating antifreeze protein constructs that reduce the concentration of protein needed to observe thermal hysteresis activities would be beneficial for diverse applications including cold storage of cells or tissues, ice slurries used in refrigeration systems, and food storage. We demonstrate that conjugating multiple type I AFPs to a polyallylamine chain increases thermal hysteresis activity compared to the original protein. The reaction product is approximately twice as active when compared to the same concentration of free proteins, yielding 0.5 °C thermal hysteresis activity at 0.3 mM protein concentration. More impressively, the amount of protein required to achieve a thermal hysteresis of 0.3 °C is about 100 times lower when conjugated to the polymer (3 μM) compared to free protein (300 μM). Ice crystal morphologies observed in the presence of the reaction product are comparable to those of the protein used in the conjugation reaction. PMID:21905742

  6. Activation of brain B-Raf protein kinase by Rap1B small GTP-binding protein.

    PubMed

    Ohtsuka, T; Shimizu, K; Yamamori, B; Kuroda, S; Takai, Y

    1996-01-19

    Rap1 small GTP-binding protein has the same amino acid sequence at its effector domain as that of Ras. Rap1 has been shown to antagonize the Ras functions, such as the Ras-induced transformation of NIH 3T3 cells and the Ras-induced activation of the c-Raf-1 protein kinase-dependent mitogen-activated protein (MAP) kinase cascade in Rat-1 cells, whereas we have shown that Rap1 as well as Ras stimulates DNA synthesis in Swiss 3T3 cells. We have established a cell-free assay system in which Ras activates bovine brain B-Raf protein kinase. Here we have used this assay system and examined the effect of Rap1 on the B-Raf activity to phosphorylate recombinant MAP kinase kinase (MEK). Recombinant Rap1B stimulated the activity of B-Raf, which was partially purified from bovine brain and immunoprecipitated by an anti-B-Raf antibody. The GTP-bound form was active, but the GDP-bound form was inactive. The fully post-translationally lipid-modified form was active, but the unmodified form was nearly inactive. The maximum B-Raf activity stimulated by Rap1B was nearly the same as that stimulated by Ki-Ras. Rap1B enhanced the Ki-Ras-stimulated B-Raf activity in an additive manner. These results indicate that not only Ras but also Rap1 is involved in the activation of the B-Raf-dependent MAP kinase cascade.

  7. Modulation of Spc1 stress-activated protein kinase activity by methylglyoxal through inhibition of protein phosphatase in the fission yeast Schizosaccharomyces pombe

    SciTech Connect

    Takatsume, Yoshifumi; Izawa, Shingo; Inoue, Yoshiharu

    2007-11-30

    Methylglyoxal, a ubiquitous metabolite derived from glycolysis has diverse physiological functions in yeast cells. Previously, we have reported that extracellularly added methylglyoxal activates Spc1, a stress-activated protein kinase (SAPK), in the fission yeast Schizosaccharomyces pombe [Y. Takatsume, S. Izawa, Y. Inoue, J. Biol. Chem. 281 (2006) 9086-9092]. Phosphorylation of Spc1 by treatment with methylglyoxal in S. pombe cells defective in glyoxalase I, an enzyme crucial for the metabolism of methylglyoxal, continues for a longer period than in wild-type cells. Here we show that methylglyoxal inhibits the activity of the protein phosphatase responsible for the dephosphorylation of Spc1 in vitro. In addition, we found that methylglyoxal inhibits human protein tyrosine phosphatase 1B (PTP1B) also. We propose a model for the regulation of the activity of the Spc1-SAPK signaling pathway by methylglyoxal in S. pombe.

  8. α/β-Peptide Foldamers Targeting Intracellular Protein-Protein Interactions with Activity in Living Cells.

    PubMed

    Checco, James W; Lee, Erinna F; Evangelista, Marco; Sleebs, Nerida J; Rogers, Kelly; Pettikiriarachchi, Anne; Kershaw, Nadia J; Eddinger, Geoffrey A; Belair, David G; Wilson, Julia L; Eller, Chelcie H; Raines, Ronald T; Murphy, William L; Smith, Brian J; Gellman, Samuel H; Fairlie, W Douglas

    2015-09-01

    Peptides can be developed as effective antagonists of protein-protein interactions, but conventional peptides (i.e., oligomers of l-α-amino acids) suffer from significant limitations in vivo. Short half-lives due to rapid proteolytic degradation and an inability to cross cell membranes often preclude biological applications of peptides. Oligomers that contain both α- and β-amino acid residues ("α/β-peptides") manifest decreased susceptibility to proteolytic degradation, and when properly designed these unnatural oligomers can mimic the protein-recognition properties of analogous "α-peptides". This report documents an extension of the α/β-peptide approach to target intracellular protein-protein interactions. Specifically, we have generated α/β-peptides based on a "stapled" Bim BH3 α-peptide, which contains a hydrocarbon cross-link to enhance α-helix stability. We show that a stapled α/β-peptide can structurally and functionally mimic the parent stapled α-peptide in its ability to enter certain types of cells and block protein-protein interactions associated with apoptotic signaling. However, the α/β-peptide is nearly 100-fold more resistant to proteolysis than is the parent stapled α-peptide. These results show that backbone modification, a strategy that has received relatively little attention in terms of peptide engineering for biomedical applications, can be combined with more commonly deployed peripheral modifications such as side chain cross-linking to produce synergistic benefits.

  9. α/β-Peptide Foldamers Targeting Intracellular Protein-Protein Interactions with Activity in Living Cells

    PubMed Central

    Checco, James W.; Lee, Erinna F.; Evangelista, Marco; Sleebs, Nerida J.; Rogers, Kelly; Pettikiriarachchi, Anne; Kershaw, Nadia J.; Eddinger, Geoffrey A.; Belair, David G.; Wilson, Julia L.; Eller, Chelcie H.; Raines, Ronald T.; Murphy, William L.; Smith, Brian J.; Gellman, Samuel H.; Fairlie, W. Douglas

    2015-01-01

    Peptides can be developed as effective antagonists of protein-protein interactions, but conventional peptides (i.e., oligomers of L-α-amino acids) suffer from significant limitations in vivo. Short half-lives due to rapid proteolytic degradation and an inability to cross cell membranes often preclude biological applications of peptides. Oligomers that contain both α- and β-amino acid residues (“α/β-peptides”) manifest decreased susceptibility to proteolytic degradation, and when properly designed these unnatural oligomers can mimic the protein-recognition properties of analogous “α-peptides”. This report documents an extension of the α/β-peptide approach to target intracellular protein-protein interactions. Specifically, we have generated α/β-peptides based on a “stapled” Bim BH3 α-peptide, which contains a hydrocarbon crosslink to enhance α-helix stability. We show that a stapled α/β-peptide can structurally and functionally mimic the parent stapled α-peptide in its ability to enter certain types of cells and block protein-protein interactions associated with apoptotic signaling. However, the α/β-peptide is nearly 100-fold more resistant to proteolysis than is the parent α-peptide. These results show that backbone modification, a strategy that has received relatively little attention in terms of peptide engineering for biomedical applications, can be combined with more commonly deployed peripheral modifications such as side chain crosslinking to produce synergistic benefits. PMID:26317395

  10. Activation of Exchange Protein Activated by Cyclic-AMP Enhances Long-Lasting Synaptic Potentiation in the Hippocampus

    ERIC Educational Resources Information Center

    Gelinas, Jennifer N.; Banko, Jessica L.; Peters, Melinda M.; Klann, Eric; Weeber, Edwin J.; Nguyen, Peter V.

    2008-01-01

    cAMP is a critical second messenger implicated in synaptic plasticity and memory in the mammalian brain. Substantial evidence links increases in intracellular cAMP to activation of cAMP-dependent protein kinase (PKA) and subsequent phosphorylation of downstream effectors (transcription factors, receptors, protein kinases) necessary for long-term…

  11. An allosteric role for receptor activity-modifying proteins in defining GPCR pharmacology

    PubMed Central

    J Gingell, Joseph; Simms, John; Barwell, James; Poyner, David R; Watkins, Harriet A; Pioszak, Augen A; Sexton, Patrick M; Hay, Debbie L

    2016-01-01

    G protein-coupled receptors are allosteric proteins that control transmission of external signals to regulate cellular response. Although agonist binding promotes canonical G protein signalling transmitted through conformational changes, G protein-coupled receptors also interact with other proteins. These include other G protein-coupled receptors, other receptors and channels, regulatory proteins and receptor-modifying proteins, notably receptor activity-modifying proteins (RAMPs). RAMPs have at least 11 G protein-coupled receptor partners, including many class B G protein-coupled receptors. Prototypic is the calcitonin receptor, with altered ligand specificity when co-expressed with RAMPs. To gain molecular insight into the consequences of this protein–protein interaction, we combined molecular modelling with mutagenesis of the calcitonin receptor extracellular domain, assessed in ligand binding and functional assays. Although some calcitonin receptor residues are universally important for peptide interactions (calcitonin, amylin and calcitonin gene-related peptide) in calcitonin receptor alone or with receptor activity-modifying protein, others have RAMP-dependent effects, whereby mutations decreased amylin/calcitonin gene-related peptide potency substantially only when RAMP was present. Remarkably, the key residues were completely conserved between calcitonin receptor and AMY receptors, and between subtypes of AMY receptor that have different ligand preferences. Mutations at the interface between calcitonin receptor and RAMP affected ligand pharmacology in a RAMP-dependent manner, suggesting that RAMP may allosterically influence the calcitonin receptor conformation. Supporting this, molecular dynamics simulations suggested that the calcitonin receptor extracellular N-terminal domain is more flexible in the presence of receptor activity-modifying protein 1. Thus, RAMPs may act in an allosteric manner to generate a spectrum of unique calcitonin receptor

  12. Role of Tet proteins in enhancer activity and telomere elongation

    PubMed Central

    Lu, Falong; Liu, Yuting; Jiang, Lan; Yamaguchi, Shinpei

    2014-01-01

    DNA methylation at the C-5 position of cytosine (5mC) is one of the best-studied epigenetic modifications and plays important roles in diverse biological processes. Iterative oxidation of 5mC by the ten-eleven translocation (Tet) family of proteins generates 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). 5fC and 5caC are selectively recognized and excised by thymine DNA glycosylase (TDG), leading to DNA demethylation. Functional characterization of Tet proteins has been complicated by the redundancy between the three family members. Using CRISPR/Cas9 technology, we generated mouse embryonic stem cells (ESCs) deficient for all three Tet proteins (Tet triple knockout [TKO]). Whole-genome bisulfite sequencing (WGBS) analysis revealed that Tet-mediated DNA demethylation mainly occurs at distally located enhancers and fine-tunes the transcription of genes associated with these regions. Functional characterization of Tet TKO ESCs revealed a role for Tet proteins in regulating the two-cell embryo (2C)-like state under ESC culture conditions. In addition, Tet TKO ESCs exhibited increased telomere–sister chromatid exchange and elongated telomeres. Collectively, our study reveals a role for Tet proteins in not only DNA demethylation at enhancers but also regulating the 2C-like state and telomere homeostasis. PMID:25223896

  13. G-protein Coupled Receptor 30 Interacts with Receptor Activity Modifying Protein 3 and Confers Sex-Dependent Cardioprotection

    PubMed Central

    Lenhart, Patricia M.; Broselid, Stefan; Barrick, Cordelia J.; Leeb-Lundberg, L.M. Fredrik; Caron, Kathleen M.

    2013-01-01

    Receptor activity modifying protein 3 (RAMP3) is a single pass transmembrane protein known to interact with and affect the trafficking of several G-protein coupled receptors (GPCRs). We sought to determine whether RAMP3 interacts with G-protein coupled receptor 30 (GPR30), also known as G-protein estrogen receptor 1 (GPER1). GPR30 is a GPCR that binds estradiol and has important roles in cardiovascular and endocrine physiology. Utilizing bioluminescence resonance energy transfer titration studies, co-immunoprecipitation, and confocal microscopy, we show that GPR30 and RAMP3 interact. Furthermore, the presence of GPR30 leads to increased expression of RAMP3 at the plasma membrane in HEK293 cells. In vivo, there are marked sex differences in the subcellular localization of GPR30 in cardiac cells, and the hearts of Ramp3−/− mice also show signs of GPR30 mislocalization. To determine whether this interaction might play a role in cardiovascular disease, we treated Ramp3+/+ and Ramp3−/− mice on a heart disease-prone genetic background with G-1, a specific agonist for GPR30. Importantly, this in vivo activation of GPR30 resulted in a significant reduction in cardiac hypertrophy and perivascular fibrosis that is both RAMP3- and sex-dependent. Our results demonstrate that GPR30-RAMP3 interaction has functional consequences on the localization of these proteins both in vitro and in vivo, and that RAMP3 is required for GPR30-mediated cardioprotection. PMID:23674134

  14. Signalling pathway leading to an activation of mitogen-activated protein kinase by stimulating M3 muscarinic receptor.

    PubMed

    Kim, J Y; Yang, M S; Oh, C D; Kim, K T; Ha, M J; Kang, S S; Chun, J S

    1999-01-15

    The signalling pathway leading to an activation of mitogen-activated protein (MAP) kinase subtypes Erk-1 and -2 upon stimulation of muscarinic receptor with carbachol in human neuroblastoma SK-N-BE2(C) cells was investigated. Carbachol activated Erk-1/-2 by stimulating M3 muscarinic receptor, as determined by specific antagonists for indivi