| 8798570 |
Ligand activation of ELK receptor tyrosine kinase promotes its association with Grb10 and Grb2 in vascular endothelial cells |
10.1074/jbc.271.38.23588. |
J Biol Chem |
Ligand activation of ELK receptor tyrosine kinase promotes its association with Grb10 and Grb2 in vascular endothelial cells
Abstract
- ELK is a member of the Eph-related tyrosine kinase family that includes receptors signaling axonal guidance, neuronal bundling, and angiogenesis. We recently identified ELK expression in human renal microvascular endothelial cells and sought to identify intracellular proteins through which it signals responses. The cytoplasmic domain of ELK was used as "bait" in a yeast two-hybrid screen to identify interactive proteins expressed from a randomly primed embryonic murine library (E9.5-10.5). Among interactive products of 76 cDNAs characterized, 10 nonidentical, overlapping clones encoded the SH2 domain of the recently reported Grb10 adapter protein, and an additional 3 encoded Grb2. A self-phosphorylated recombinant, baculovirus-expressed GST-ELKcy fusion protein bound Grb10 and Grb2 from human renal microvascular endothelial cell extracts, while the unphosphorylated fusion form did not. Site-directed mutation identified Tyr-929 as a putative phosphorylation site required for Grb10, but not Grb2, interaction in yeast and recombinant protein assays. The ELK ligand, LERK-2/Fc, stimulated tyrosine phosphorylation of ELK, and recruitment of Grb10 and Grb2 to endothelial ELK receptors recovered by wheat germ agglutinin lectin and immunoprecipitation. These findings define ligand-activated interaction between ELK and the SH2 domains of Grb2 and the newly identified Grb10 protein that shares homology with a Caenorhabditis elegans gene product implicated in neural cell migration.
|
| 8801520 |
Immunosuppressive activity of hymenistatin I |
10.1016/0196-9781(95)02123-x. |
Peptides |
Immunosuppressive activity of hymenistatin I
Abstract
- Hymenistatin I (HS-I), a cyclic octapeptide c-(-Pro-Pro-Tyr-Val-Pro-Leu-Ile-Ile-), was synthesized by the solid-phase peptide synthesis method and examined for its immunosuppressive activity in the humoral and cellular immune responses. The peptide activity was tested on cell lines producing various cytokines. The results are compared with the activity of the well-known immunosuppressive agent cyclosporin A (CsA). It was found that hymenistatin I exerts immunosuppressive effect (both in the humoral and cellular immune responses) comparable with that of CsA. Comparison of the influence of HS-I and CsA on cytokines production suggests that the mechanisms of the interaction with the immunological system are substantially different for the two compounds tested.
|
| 8806510 |
Inhibition of HIV-1 replication by cyclosporine A or related compounds correlates with the ability to disrupt the Gag-cyclophilin A interaction |
10.1006/viro.1996.0421. |
Virology |
Inhibition of HIV-1 replication by cyclosporine A or related compounds correlates with the ability to disrupt the Gag-cyclophilin A interaction
Abstract
- The HIV-1 Gag polyprotein specifically incorporates the cellular peptidylprolyl isomerase cyclophilin A into virions. HIV-1 replication is inhibited by cyclosporine A, an immunosuppressive drug which binds with high affinity to cyclophilin A and precludes interaction with the Gag polyprotein. Using a panel of four drugs, including cyclosporine A, two nonimmunosuppressive analogues of cyclosporine A which bind to cyclophilin A but which cannot form a tertiary complex with the calcium-dependent phosphatase calcineurin, and the structurally unrelated immunosuppressant FK506, we demonstrated that the antiviral effect of cyclosporine A is not due to blockade of calcineurin-mediated signal transduction pathways. Rather, the effectiveness of cyclosporine A and related compounds at inhibiting HIV-1 replication correlates with cyclophilin A-binding affinity and with the ability to disrupt the interaction between cyclophilin A and the HIV-1 Gag polyprotein. These results support the contention that the Gag-cyclophilin A interaction is required for HIV-1 replication.
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| 8806703 |
Expression and characterization of human pancreatic preprocarboxypeptidase A1 and preprocarboxypeptidase A2 |
10.1006/abbi.1996.0310. |
Arch Biochem Biophys |
Expression and characterization of human pancreatic preprocarboxypeptidase A1 and preprocarboxypeptidase A2
Abstract
- We are investigating the potential utility of human carboxypeptidases A in antibody-directed enzyme prodrug therapy (ADEPT). Hybridization screening of a human pancreatic cDNA library with cDNA probes that encoded either rat carboxypeptidase A1 (rCPA1) or carboxypeptidase A2 (rCPA2) was used to clone the human prepro-CPA homologs. After expression of the respective pro-hCPA cDNA in Saccharomyces cerevisiae, the enzymes were purified to homogeneity by a combination of hydrophobic and ion-exchange chromatography. Purified hCPA1 and hCPA2 migrate as a single protein band with M(r) 34,000 when subjected to gel electrophoresis in the presence of sodium dodecyl sulfate under reducing conditions. Kinetic studies of the purified enzymes with hippuryl-L-phenylalanine resulted in kcat/Km values of 57,000 and 19,000 M-1 s-1 for hCPA1 and hCPA2, respectively. Using the ester substrate, hippuryl-D, L-phenyllactate, we found unique esterase/ peptidase specific activity ratios among hCPA1, hCPA2, rCPA1, and bovine CPA (bCPA) ranging from 13 to 325. Two potential ADEPT substrates, methotrexate-alpha-phenylalanine (MTX-Phe) and methotrexate-alpha-(1-naphthyl)alanine (MTX-naphthylAla) were also analyzed. The kcat/Km values for MTX-Phe were 440,000 and 90,000 M-1 s-1 for hCPA1 and hCPA2, respectively, and for MTX-naphthylAla these values were 1400 and 1,400,000 M-1 s-1 for hCPA1 and hCPA2, respectively. The kinetic data show that hCPA2 has a larger substrate binding site than the hCPA1 enzyme. Differences between hCPA1 and hCPA2 were also observed in thermal stability experiments at 60 degrees C where the half-life for thermal denaturation of hCPA2 is eightfold longer than that for hCPA1. These experiments indicate that hCPA1 and hCPA2 are potential candidates for use in a human-based ADEPT approach.
|
| 8808632 |
The dorsoventral regulatory gene cassette spätzle/Toll/cactus controls the potent antifungal response in Drosophila adults |
10.1016/s0092-8674(00)80172-5. |
Cell |
The dorsoventral regulatory gene cassette spätzle/Toll/cactus controls the potent antifungal response in Drosophila adults
Abstract
- The cytokine-induced activation cascade of NF-kappaB in mammals and the activation of the morphogen dorsal in Drosophila embryos show striking structural and functional similarities (Toll/IL-1, Cactus/I-kappaB, and dorsal/NF-kappaB). Here we demonstrate that these parallels extend to the immune response of Drosophila. In particular, the intracellular components of the dorsoventral signaling pathway (except for dorsal) and the extracellular Toll ligand, spätzle, control expression of the antifungal peptide gene drosomycin in adults. We also show that mutations in the Toll signaling pathway dramatically reduce survival after fungal infection. Antibacterial genes are induced either by a distinct pathway involving the immune deficiency gene (imd) or by combined activation of both imd and dorsoventral pathways.
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| 8823521 |
The effect of chitinase inhibitors, cyclo(Arg-Pro) against cell separation of Saccharomyces cerevisiae and the morphological change of Candida albicans |
10.7164/antibiotics.49.829. |
J Antibiot (Tokyo) |
The effect of chitinase inhibitors, cyclo(Arg-Pro) against cell separation of Saccharomyces cerevisiae and the morphological change of Candida albicans
Abstract
|
| 8824953 |
Estrogen-like activity of cyclic peptides from Vaccaria segetalis extracts |
10.1055/s-2006-959373. |
Planta Med |
Estrogen-like activity of cyclic peptides from Vaccaria segetalis extracts
Abstract
- Methanol and ethyl acetate extracts of Wang Bu Liu Xing (seeds of Vaccaria segetalis, Caryophyllaceae) and cyclic peptides (named segetalins A and B) obtained from the extracts were shown to have an estrogen-like activity.
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| 8836771 |
Purification and mass spectrometry-based sequencing of yellow mustard (Sinapis alba L.) 6 kDa proteins. Identification as antifungal proteins |
10.1111/j.1399-3011.1996.tb01094.x. |
Int J Pept Protein Res |
Purification and mass spectrometry-based sequencing of yellow mustard (Sinapis alba L.) 6 kDa proteins. Identification as antifungal proteins
Abstract
- Three basic proteins, M1, M2A and M2B, that are substrates for plant Ca(2+)-dependent protein kinase (CDPK) were purified from seeds of yellow mustard (Sinapis alba L.) by a protocol involving batchwise chromatography on carboxymethylcellulose (CM52), cation-exchange HPLC on an SP5PW column and reversed-phase HPLC on a C18 column. The complete amino-acid sequences of these proteins have been determined employing Edman sequencing and electrospray ionization mass spectrometry (ESMS) applied to the proteins and their tryptic and chymotryptic fragments. M1 (observed mass 5676.8 +/- 1.0 Da; calculated mass 5677.57 Da), M2A (observed mass 5704.8 +/- 0.8 Da; calculated mass 5704.60 Da) and M2B (observed mass 5839.5 +/- 1.2 Da; calculated mass 5838.78 Da) have been identified as gamma-thionins, which are potent antifungal proteins. M1, M2A and M2B are phosphorylated by plant CDPK on Ser residues, the site of phosphorylation on M2A being S8 as directly confirmed by Edman sequencing and mass spectrometry of the chymotryptically generated phosphopeptide CQRPS(HPO3)GTW11. M1 and M2A have apparent calmodulin (CaM) antagonist activity with IC50 values of 4.8 +/- 1.3 microM and 5.5 +/- 1.5 microM, respectively, for inhibition of CaM-dependent myosin light chain kinase (MLCK). M2A and/or M2B interacts with dansyl-CaM in both the presence and absence of calcium.
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| 8836773 |
Gramicidin S is active against both gram-positive and gram-negative bacteria |
10.1111/j.1399-3011.1996.tb01096.x. |
Int J Pept Protein Res |
Gramicidin S is active against both gram-positive and gram-negative bacteria
Abstract
- Four linear and four cyclic analogs of gramicidin S (GS) in which D-Phe was replaced with either D-His, D-Ser, D-Tyr or D-Asn have been prepared by solid-phase peptide synthesis and characterized with respect to antibacterial, antifungal and hemolytic activity. Unlike previous reports, GS and a number of cyclic analogs were found to be active against gram-positive as well as gram-negative bacteria. GS showed MICs ranging from 3 to 12.5 micrograms/mL for gram-negative bacteria, compared to MICs of 3 micrograms/mL for gram-positive bacteria. Furthermore, these analogs were also found to exhibit antifungal activity. Unlike the cyclic analogs, all linear analogs were found to be inactive against a wide range of microorganisms tested, and showed low levels of hemolytic activity. The antibacterial activity was found to be highly dependent on the type of assay used, with solution-based assays showing greater activity against gram-negative bacteria than agar-based assays. The GS cyclic analogs were all less toxic than GS itself, with the analog containing the D-Phe to D-Tyr substitution showing the greatest activity of the synthetic analogs. Hemolytic activity in solution against human and sheep red blood cells paralleled antibiotic activity, with those peptides exhibiting greater antibiotic activity generally showing greater hemolytic activity. Membrane destabilization as monitored using the hydrophobic probe N-phenyl-1-naphthylamine was also found to parallel antibacterial and hemolytic activity of cyclic and linear analogs. These results indicate that GS and certain related analogs may have applications as broad-spectrum antibiotics and should be reevaluated for such purposes.
|
| 8841182 |
Hereditary pancreatitis is caused by a mutation in the cationic trypsinogen gene |
10.1038/ng1096-141. |
Nat Genet |
Hereditary pancreatitis is caused by a mutation in the cationic trypsinogen gene
Abstract
- Hereditary pancreatitis (HP) is a rare, early-onset genetic disorder characterized by epigastric pain and often more serious complications. We now report that an Arg-His substitution at residue 117 of the cationic trypsinogen gene is associated with the HP phenotype. This mutation was observed in all HP affected individuals and obligate carriers from five kindreds, but not in individuals who married into the families nor in 140 unrelated individuals. X-ray crystal structure analysis, molecular modelling, and protein digest data indicate that the Arg 117 residue is a trypsin-sensitive site. Cleavage at this site is probably part of a fail-safe mechanism by which trypsin, which is activated within the pancreas, may be inactivated; loss of this cleavage site would permit autodigestion resulting in pancreatitis.
|
| 8843286 |
Semisynthetic echinocandins affect cell wall deposition of Pneumocystis carinii in vitro and in vivo |
10.1128/AAC.40.8.1811. |
Antimicrob Agents Chemother |
Semisynthetic echinocandins affect cell wall deposition of Pneumocystis carinii in vitro and in vivo
Abstract
- Cyclic lipodepsipeptide compounds of the echinocandin class exhibit broad-spectrum antifungal activity and have been shown to be effective in the treatment of Pneumocystis carinii pneumonia in laboratory animal models. Previous studies have led investigators to propose that these compounds, active against fungal cell walls, are selectively active against the cyst forms of P. carinii. We demonstrate that a semisynthetic, water-soluble echinocandin analog, LY307853, is effective in reducing the number of all life cycle forms of P. carinii and is more effective in mice immunosuppressed with monoclonal antibody to L3T4+ cells than in mice immunosuppressed with dexamethasone. Treatment of P. carinii isolates with LY307853 in a short-term in vitro culture model resulted in cytoarchitectural alterations suggesting that this echinocandin may interfere with the export of surface glycoprotein and the formation of the tubular elements normally found on the surfaces of trophic forms. The cytoarchitectural changes in trophic forms treated in vitro with LY307853 were also observed in trophic forms in the lung tissue of rats treated with a closely related echinocandin analog, LY303366.
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| 8863420 |
Proposal for two new genera, Brevibacillus gen. nov. and Aneurinibacillus gen. nov |
10.1099/00207713-46-4-939. |
Int J Syst Bacteriol |
Proposal for two new genera, Brevibacillus gen. nov. and Aneurinibacillus gen. nov
Abstract
- 16S rRNA gene sequences of the type strains of 11 species belonging to the Bacillus brevis and Bacillus aneurinolyticus groups were determined. On the basis of the results of gene sequence analyses, these species were separated into two clusters. The B. brevis cluster included 10 species, namely, Bacillus brevis, Bacillus agri, Bacillus centrosporus, Bacillus choshinensis, Bacillus parabrevis, Bacillus reuszeri, Bacillus formosus, Bacillus borstelensis, Bacillus laterosporus, and Bacillus thermoruber. Bacillus aneurinolyticus and Bacillus migulanus belonged to the B. aneurinolyticus cluster. Moreover, the two clusters were phylogenetically distinct from other Bacillus, Amphibacillus, Sporolactobacillus, Paenibacillus, and Alicyclobacillus species. On the basis of our data, we propose reclassification of the B. brevis cluster as Brevibacillus gen. nov. and reclassification of the B. aneurinolyticus cluster as Aneurinibacillus gen. nov. By using 16S rRNA gene sequence alignments, two specific PCR amplification primers were designed for differentiating the two new genera from each other and from other aerobic, endospore-forming organisms.
|
| 8863526 |
Novel omega-conotoxins block dihydropyridine-insensitive high voltage-activated calcium channels in molluscan neurons |
10.1046/j.1471-4159.1996.67052155.x. |
J Neurochem |
Novel omega-conotoxins block dihydropyridine-insensitive high voltage-activated calcium channels in molluscan neurons
Abstract
- We have identified two novel peptide toxins from molluscivorous Conus species that discriminate subtypes of high voltage-activated (HVA) calcium currents in molluscan neurons. The toxins were purified using assays on HVA calcium currents in the caudodorsal cells (CDCs) of the snail Lymnaea stagnalis. The CDC HVA current consists of a rapidly inactivating, transient current that is relatively insensitive to dihydropyridines (DHPs) and a slowly inactivating, DHP-sensitive L-current. The novel toxins, designated omega-conotoxins PnVIA and PnVIB, completely and selectively block the transient HVA current in CDCs with little (PnVIA) or no (PnVIB) effect on the sustained L-type current. The block is rapid and completely reversible. It is noteworthy that both PnVIA and PnVIB reveal very steep dose dependences of the block, which may imply cooperativity in toxin action. The amino acid sequences of PnVIA (GCLEVDYFCGIPFANNGLCCSGNCVFVCTPQ) and of PnVIB (DDDCEPPGNFCGMIKIGPPCCSGWCFFACA) show very little homology to previously described omega-conotoxins, although both toxins share the typical omega-conotoxin cysteine framework but have an unusual high content of hydrophobic residues and net negative charge. These novel omega-conotoxins will facilitate selective analysis of the functions of HVA calcium channels and may enable the rational design of drugs that are selective for relevant subtypes.
|
| 8874387 |
Antagonists of integrin alpha v beta 3 inhibit retinal neovascularization in a murine model |
None |
Lab Invest |
Antagonists of integrin alpha v beta 3 inhibit retinal neovascularization in a murine model
Abstract
- Integrin alpha v beta 3 is differentially expressed in angiogenic blood vessels in skin granulation tissue, and alpha v beta 3 antagonists inhibit angiogenesis in chick chorioallantoic membranes. In this study, we investigated the role of alpha v beta 3 in retinal neovascularization. There was no detectable signal for alpha v beta 3 by immunohistochemistry in normal human retina, but neovascular tissue removed from the surface of the retina of patients with diabetic retinopathy showed intense staining for alpha v beta 3 within the endothelial cells of new blood vessels. In a murine model of oxygen-induced ischemic retinopathy, there was intense staining for alpha v beta 3 in endothelial cells participating in neovascularization but no detectable staining in normal retinal blood vessels of adult mice. Synthetic peptides that bind alpha v beta 3 and perturb alpha v beta 3-mediated adhesion in vitro inhibited retinal neovascularization in the murine model when given by intraperitoneal or periocular injections. These data suggest that alpha v beta 3 antagonists may provide a useful adjunct for the treatment of retinal neovascularization.
|
| 8882429 |
Cyclic peptides from higher plants. 24.1 yunnanin C, a novel cyclic heptapeptide from Stellaria yunnanensis |
10.1021/np960123q. |
J Nat Prod |
Cyclic peptides from higher plants. 24.1 yunnanin C, a novel cyclic heptapeptide from Stellaria yunnanensis
Abstract
- A novel cytotoxic cyclic heptapeptide, yunnanin C (1), was isolated from the roots of Stellaria yunnanensis. The structure of 1, cyclo(-Gly-Ile-Gly-Phe-Tyr-Ser-Pro-), was elucidated from spectroscopic evidence and by chemical degradation.
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