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J Moss

Publications and source records attributed to J Moss.

At least 199 records · Page 11Linked to original sources
PubMed1996

Mono-ADP-ribosylation: a reversible posttranslational modification of proteins.

Mono-ADP-ribosyltransferase activity has been detected in numerous vertebrate tissues and transferase cDNAs from a few species have recently been cloned. In vitro ADP-ribosylation has been demonstrated with diverse substrates such as phosphorylase kinase, actin, and Gs alpha resulting in the alteration of substrate function. ADP-ribosylation of endogenous target proteins has been observed in chicken heterophils, rat brain, and human platelets, and integrin alpha 7 was found to be the endogenous substrate of the GPI-anchored rabbit skeletal muscle transferase. The reversibility of ADP-ribosylation is made possible by ADP-ribosylarginine hydrolases which have been isolated and cloned from rodent and human tissues. The transferases and hydrolases could in principle form an intracellular ADP-ribosylation regulatory cycle. In the case of the skeletal muscle transferases, however, processing of ADP-ribosylated integrin alpha 7 is carried out by phosphodiesterases and possibly phosphatases (Fig. 1). Most bacterial toxin and eukaryotic mono-ADP-ribosyltransferases, and perhaps other NAD-utilizing enzymes such as the RT6 family of proteins, share a common catalytic-site structure despite a lack of overall sequence identity. The transferases that have been studied thus far possess a critical glutamic acid and other amino acids at the catalytic cleft which function to position NAD for nucleophilic attack at the N-glycosidic linkage for either ADP-ribose transfer or NAD hydrolysis. The amino acid differences among transferases at the active site may reflect different catalytic mechanisms of ADP-ribosylation or may be required for accommodating the different ADP-ribose acceptor molecules.

ADP Ribose Transferases↗
PubMed1996

Effect of oral antihistamine premedication on mivacurium-induced histamine release and side effects.

In this randomized, double-blind, placebo-controlled study, we have examined histamine release, haemodynamic and cutaneous effects of mivacurium administered in low (0.105 mg kg-1 = 1.5 x ED95) and high (0.21 mg kg-1 = 3 x ED95) doses and assessed if oral pretreatment with H1/H2 antagonists would blunt the effects of mivacurium-induced histamine release. Patients received either ranitidine 300 mg and dimethindene 0.1 mg kg-1 (H1 blocker) or placebo, orally 1 h before induction of anaesthesia. Twelve patients were allocated to each group. Although plasma concentrations of histamine increased significantly in three patients in the placebo group given low-dose mivacurium, the mean value for the group was unchanged. Plasma concentrations of histamine increased significantly in five patients in the placebo group after high-dose mivacurium and the mean value was increased. There was no consistent correlation between haemodynamic changes, cutaneous manifestations and histamine concentrations. Significant cardiovascular reactions occurred in six patients in the placebo groups and in only one patient treated with antihistamines.

Adolescent↗
PubMed1996

Alterations of adenylyl cyclase-linked G proteins in rat liver during aging.

beta-Adrenergic stimulation of adenylyl cyclase in rat liver increases during aging. We examined whether this increase is related to alterations in the stimulatory and inhibitory G proteins (Gs and Gi) linked to adenylyl cyclase. Levels of immunoreactive alpha- and beta-subunits of Ga and Gi in liver plasma membranes from 6-, 12-, 18-, and 24-mo-old rats were unchanged with age, as was pertussis toxin-catalyzed [32P]ADP ribosylation of Gi alpha. Cholera toxin-catalyzed [32P]ADP ribosylation of Ga alpha and Gs bioactivity, assessed as reconstitution of adenylyl cyclase activity in S49 cyc- cell membranes, increased two- to threefold between 6 and 12-18 mo, and declined by 24 mo. Recombinant ADP ribosylation factor (ARF) enhanced cholera toxin labeling of Gs alpha at all ages, yet abolished the increase in toxin labeling at 12-18 mo. Auto-ADP ribosylation of the cholera toxin A1 peptide also increased transiently with age. Alteration of Gs alpha, as reflected by increased cholera toxin labeling and Gs bioactivity, may be involved in the regulation of beta-adrenergic-responsive adenylyl cyclase in rat liver during aging. Moreover, changes in endogenous ARF levels could contribute to age differences in cholera toxin labeling of Gs alpha.

ADP-Ribosylation Factors↗
PubMed1996

The composition of wide-spaced collagen in normal and diseased Descemet's membrane.

Descemet's membrane, the specialised basement membrane of the corneal endothelium, contains a form of extracellular matrix described as wide-spaced collagen. In healthy human Descemet's membrane, wide-spaced collagen forms a highly ordered array in a region called the anterior banded zone. However, in corneal endotheliopathies such as Fuchs' endothelial dystrophy and the iridocorneal-endothelial syndrome large amounts of wide-spaced collagen are deposited posterior to Descemet's membrane in a grotesque parody of the anterior banded zone termed a posterior collagenous layer. The purpose of this study was to identify the composition of the wide-spaced collagen found in the Descemet's membrane of normal and diseased human corneas. Tissue from three normal human corneas, three from patients with Fuchs' endothelial dystrophy and five from patients with the iridocorneal-endothelial syndrome was prepared for immuno-electron microscopy by freezing or embedding in Lowicryl K4M resin. Immunocytochemistry on ultrathin sections was performed with antibodies to collagen Types I, III, V, VI and VIII, fibronectin, laminin, P component and tenascin. Ultrastructural labelling of the wide-spaced collagen in the anterior banded zone of normal and diseased corneas and also of the wide-spaced collagen in the posterior collagenous layer of all the diseased corneas was demonstrated with antibody to collagen Type VIII. Wide-spaced collagen was not labelled by any of the other antibodies used. Large amounts of Type VIII collagen are present in discrete regions of healthy and diseased Descemet's membrane. The deposition of Type VIII collagen may significantly influence the pathobiology of the corneal endotheliopathies.

Collagen↗
PubMed1996

Scleredema diabeticorum of Buschke confined to the thighs.

We describe a patient with insulin-dependent diabetes without vascular complications in whom scleredema was confined to the thighs. Electron microscopy demonstrated heterogeneity in both the size and density of the collagen fibrils and the presence of filamentous material between them.

Adult↗
PubMed1996

The histopathology of the iridocorneal-endothelial syndrome.

The iridocorneal-endothelial (ICE) syndrome is characterised clinically by a "hammered-silver" appearance of the corneal endothelium, corneal failure, glaucoma, and iris destruction. Specular photomicroscopic studies of the corneal endothelium have demonstrated a population of abnormal cells termed "ICE cells." The purpose of this study was to define the histological appearances typical of this disease and in particular the ultrastructural morphology of the ICE cell. Thirty-five corneas, 11 trabeculectomy specimens, and 3 failed corneal grafts taken from patients with the ICE syndrome were examined by transmission and scanning electron microscopy. Comparison was made with seven normal corneas. Ten corneas and two trabeculectomy specimens demonstrated a population of well-differentiated cells with epithelial features such as desmosomes, tonofilaments, and microvilli. Other cell types identified were cells that resembled those of normal corneal endothelium, inflammatory cells, and cells with a fibroblast-like morphology. It seems likely that the epithelial cells of our specimens are the histological equivalent of the ICE cell seen by specular photomicroscopy. The other cell types may be either residual normal endothelial cells or else arise from secondary phenomena of various kinds.

Cornea↗
PubMed1995

Hydrophobicity and subunit interactions of rod outer segment proteins investigated using Triton X-114 phase partitioning.

Triton X-114 phase partitioning, a procedure used for purifying integral membrane proteins, was used to study protein components of the mammalian visual transduction cascade. An integral membrane protein, rhodopsin, and two isoprenylated protein complexes, cyclic GMP phosphodiesterase and Gt beta gamma, partitioned into the detergent-rich phase. Arrestin, a soluble protein, accumulated in the aqueous phase. Gt alpha distributed about equally between phases whether GDP (Gt alpha.GDP) or GTP (Gt alpha.GTP) was bound. Gt beta gamma increased recovery of Gt alpha.GDP but not Gt alpha.GTP in the detergent phase. Trypsin-treated Gt alpha, which lacks the fatty acylated amino-terminal 2-kDa region, accumulated to a greater extent in the aqueous phase than did intact Gt alpha. Trypsinized cGMP phosphodiesterase, which lacks the isoprenyl group, partitioned into the aqueous phase. A carboxyl-terminal truncated mutant (Val-331 stop) of Gt alpha accumulated more in the aqueous phase then did recombinant full-length Gt alpha, supporting the role of the carboxyl terminus in increasing its hydrophobicity. N-Myristoylated recombinant Go alpha was more hydrophobic than recombinant Go alpha without myristate. ADP-ribosylation of Gt alpha catalyzed by NAD:arginine ADP-ribosyltransferase, but not by pertussis toxin, increased hydrophilicity. Triton X-114 phase partitioning can thus semiquantify the hydrophobic nature of proteins and protein domains. It may aid in evaluating changes associated with post-translational protein modification and protein-protein interactions in a defined system.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

cAMP-independent effects of cholera toxin on B cell activation. III. Cholera toxin A subunit-mediated ADP-ribosylation acts synergistically with ionomycin or IL-4 to induce B cell proliferation.

To investigate whether ADP-ribosylation of proteins by cholera toxin could influence B cell activation, B cells were incubated with the A subunit of cholera toxin. Ionomycin acted synergistically to induce B cell proliferation with the A subunit of cholera toxin but not with cAMP-enhancing agents or with the B subunit of cholera toxin, suggesting that the synergistic effect of the A subunit was mediated via ADP-ribosylation and not via cAMP elevations or ganglioside GM1 binding. Indeed, inhibitors of ADP-ribosylation blocked the synergistic effect. Unlike anti-Ig, B cell proliferation stimulated by LPS or by the combination of the A subunit and ionomycin was observed in protein kinase C (PKC)-depleted B cells. However, neither the A subunit nor ionomycin enhanced B cell proliferation stimulated by low dose LPS, suggesting that the A subunit plus ionomycin stimulated an activation pathway distinct from the LPS-stimulated pathway. Additionally, unlike LPS, the A subunit plus ionomycin did not stimulate B cells in vitro to secrete Ig. IL-4 acted synergistically with the A subunit to induce B cell proliferation to the same extent as it did with anti-Ig; unlike the anti-Ig plus IL-4 synergy, however, the A subunit plus IL-4-mediated synergy persisted in PKC-depleted B cells. Taken together, our data suggest that cholera toxin A subunit-catalyzed ADP-ribosylation modifies a non-Gs protein involved in the activation of B cells, either through a novel pathway or at a point distal to the activation of PKC along the anti-Ig-stimulated pathway.

Adenosine Diphosphate Ribose↗
PubMed1995

Structural diversity in the 5'-untranslated region of cytokine-stimulated human inducible nitric oxide synthase mRNA.

Inducible nitric oxide synthase, the critical enzyme responsible for the enhanced synthesis of nitric oxide in inflammatory states, is widely expressed in mammalian cells. To evaluate potential regulatory roles of the 5'-untranslated region (UTR) in the human inducible nitric oxide synthase gene, the transcription initiation sites and structure of the 5'-UTR of human inducible nitric oxide synthase were examined. Freshly isolated human alveolar macrophages, bronchial epithelial cells, and several types of cultured cells were evaluated following stimulation with cytokines (i.e. interferon-gamma, interleukin-1 beta, tumor necrosis factor-alpha, and interleukin-6). The mRNA was analyzed by reverse transcription-polymerase chain reaction. Northern analysis, and 5'-rapid amplification of cDNA ends. Despite the presence of a TATA box in the promoter region, multiple transcription initiation sites were observed, some extending several hundred base pairs upstream from the main TATA-directed initiation site. Alternative splicing in the 5'-UTR of human inducible nitric oxide synthase mRNA resulted in further diversity. The TATA-independent inducible nitric oxide synthase mRNA transcripts were up-regulated by cytokines. The long and complex 5'-UTRs contain eight partially overlapping open reading frames upstream of the putative inducible nitric oxide synthase ATG, which may have an important role in translational regulation of human inducible nitric oxide synthase mRNA.

Alternative Splicing↗
PubMed1995

Processing of ADP-ribosylated integrin alpha 7 in skeletal muscle myotubes.

Integrin alpha 7 is a major substrate in skeletal muscle cells for the cell surface, glycosylphosphatidylinositol-anchored, arginine-specific ADP-ribosyltransferase. Since ADP-ribosylarginine hydrolase, the enzyme responsible for cleavage of the ADP-ribosylarginine bond and a component with the transferase of a putative ADP-ribosylation cycle, is cytosolic, the processing of ADP-ribosylated integrin alpha 7 was investigated. Following incubation of differentiated mouse C2C12 myoblasts with [adenylate-32P]NAD and analysis by SDS-polyacrylamide gel electrophoresis under reducing conditions, two [32P]ADP-ribosylated forms of integrin alpha 7 were resolved. By pulse-chase and purification of the radiolabeled proteins on a laminin affinity column, it was demonstrated that a 105-kDa ADP-ribosylated form originated from a mono-ADP-ribosylated 102-kDa form and represented integrin alpha 7 modified at more than one site. The additional site(s) of modification, utilized at higher NAD concentrations, were located in the 63-kDa N-terminal segment of integrin alpha 7. Both [32P]ADP-ribosylated integrins were loosely associated with the cytoskeleton, bound to laminin affinity columns, and immunoprecipitated with antibodies to integrin beta 1. 32P label was rapidly removed from [32P]ADP-ribosylated integrin alpha 7 at either site of modification, a process inhibited by free ADP-ribose or p-nitrophenylthymidine-5'-monophosphate, an alternative substrate of 5'-nucleotide phosphodiesterase. The processed integrin alpha 7 was unavailable for subsequent ADP-ribosylation, although the amount of surface integrin alpha 7 remained constant. During the processing, no loss of label was observed from integrin alpha 7 radiolabeled with [14C]NAD, containing 14C in the nicotinamide proximal ribose, consistent with degradation of the ADP-ribose moiety by a cell surface 5'-nucleotide phosphodiesterase. Thus, cell surface ADP-ribosylation, in contrast to intracellular ADP-ribosylation, is not readily reversed by ADP-ribosylarginine hydrolase and seems to operate outside the postulated ADP-ribosylation cycle.

ADP Ribose Transferases↗
PubMed1995

Isolation of an amino-terminal deleted recombinant ADP-ribosylation factor 1 in an activated nucleotide-free state.

ADP-ribosylation factors (ARFs) are approximately 20-kDa guanine nucleotide-binding proteins that activate cholera toxin ADP-ribosyltransferase in vitro and participate in intracellular vesicular membrane trafficking. ARFs are activated when bound GDP is replaced by GTP and inactivated by hydrolysis of bound GTP to yield ARF-GDP. Usually, ARFs are isolated in an inactive GDP-bound state and require addition of GTP along with detergent or phospholipid for activity. Purified mutant recombinant ARF1 lacking the first 13 amino acids (r delta 13ARF1-P) stimulated cholera toxin activity essentially equally with or without added GTP (and phospholipid or detergent), at least in part due to the presence of bound nucleotides, which later were identified as GTP and GDP. Nucleotide-free r delta 13ARF1 (r delta 13ARF1-F), prepared by dialysis against 7 M urea, was active without added GTP in the absence of SDS but inactive without added GTP in its presence. Renaturation of r delta 13ARF1-F in the presence of GTP, ITP, or GDP yielded, respectively, r delta 13ARF1-GTP and r delta 13ARF1-ITP, which were active, and r delta 13ARF1-GDP, which was inactive. Effects of phospholipids and detergents on nucleotide exchangeability evaluated as effects on activity of rARF1 and r delta 13ARF1-F differed. With r delta 13ARF1-F, 100 microM ITP and 100 microM GTP were essentially equally effective in the presence of cardiolipin or SDS. The finding that r delta 13ARF1 differs from rARF1 in the effects of phospholipids and detergents on nucleotide binding is consistent with the conclusion that the ARF amino terminus plays an important role in nucleotide binding and its specificity as well as the molecular conformation and associated activity.

ADP-Ribosylation Factor 1↗
PubMed1995

Effects of methylnaltrexone on morphine-induced inhibition of contraction in isolated guinea-pig ileum and human intestine.

We investigated the effects of methylnaltrexone on morphine-induced inhibition of smooth muscle-strip contraction in isolated guinea-pig ileum and human small intestine. The longitudinal muscle-strip was immersed in a temperature-controlled (37 degrees C) bath containing a physiological solution of 95% O2 and 5% CO2 with pH 7.4. Muscle contraction was elicited by transmural electrical stimulation with a pulse duration of 0.5 ms at frequencies of 1-50 Hz for 5-10 s at 1-3-min intervals. Muscle contraction was blocked by tetrodotoxin or atropine in both preparations. When methylnaltrexone was applied to the bath, the force produced by muscle contraction was enhanced up to approximately 30%. Stimulation-elicited muscle contraction was inhibited by morphine, which decreased the force of contraction 42 +/- 9.5% (S.D.) in the human intestine preparation and 35 +/- 8.6% in guinea-pig ileum at the inhibitory concentration 70% (IC70). Methylnaltrexone effectively antagonized the effects of morphine-induced inhibition of muscle-strip contraction. In the guinea-pig ileum preparation, methylnaltrexone at 30, 100 and 300 nM blocked 25 +/- 10.5%, 74 +/- 7.2% and 89 +/- 9.9% of morphine-induced (300 nM) inhibition, respectively. In the human intestine preparation, methylnaltrexone at the same concentrations blocked 57 +/- 10.9%, 74 +/- 12.9% and 92 +/- 7.2% of morphine-induced (100 nM) inhibition, respectively. The relative ratio of methylnaltrexone to morphine was higher in human intestine (1:1) than in the guinea-pig ileum preparation (1:3). These data provide preliminary information for clinical studies to evaluate the efficacy of methylnaltrexone in preventing or reducing morphine-induced antimotility and antitransit actions.

Adult↗
PubMed1995

Involvement of N-myristoylation in monoclonal antibody recognition sites on chimeric G protein alpha subunits.

Monoclonal antibody, LAS-2, directed against the alpha subunit of transducin (Gt alpha), inhibited Gt beta gamma-dependent, pertussis toxin-catalyzed ADP ribosylation of Gt alpha and was specific for Gt alpha. Immunoblotting studies on proteolytic fragments of Gt alpha were consistent with an amino-terminal epitope. To define the antibody recognition site, recombinant Gt alpha was synthesized in Escherichia coli cotransfected with or without yeast N-myristoyl-transferase. Amino-terminal fatty acylation of Gt alpha, verified by use of radiolabeled fatty acid, was required for immunoreactivity. LAS-2 did not react with a chimeric protein consisting of residues 1-9 of Gt alpha and the remainder Go alpha, regardless of its myristoylation. Immunoreactivity was observed when amino acids 1-17 of Gt alpha were present in a Go alpha chimera and the protein was amino-terminally myristoylated; there was no reactivity without myristoylation. It appears that the LAS-2 epitope requires both Gt alpha-specific sequence in amino acids 10-17 and a fatty acyl group in proximity to these residues. These results are consistent with the hypothesis that the myristoyl group is essential for protein structure; conceivably it "folds back" on and stabilizes the amino-terminal structure of Gt alpha as opposed to protruding from an amino-terminal alpha-helix and serving as an amino-terminal membrane anchor.

Animals↗
PubMed1995

Conservation of a common motif in enzymes catalyzing ADP-ribose transfer. Identification of domains in mammalian transferases.

Bacterial toxin ADP-ribosyltransferases, e.g. diphtheria toxin (DT) and pertussis toxin, have in common consensus sequences involved in catalytic activity, which are localized to three regions. Region I is notable for a histidine or arginine; region II, approximately 50-75 amino acids downstream, is rich in aromatic/hydrophobic amino acids; and region III, further downstream, has a glutamate and other acidic amino acids. A similar motif was observed in the sequence of the glycosylphosphatidylinositol-linked muscle ADP-ribosyltransferase. Site-directed mutagenesis was performed to verify the role of this motif. Proteins were expressed in rat adenocarcinoma cells, released from the cell with phosphatidylinositol-specific phospholipase C, and quantified with polyclonal antibodies. Transferase His114 in region I aligned with His21 of DT; as with DT, the H114N mutant was active. Aromatic/hydrophobic amino acids (region II) were found approximately 30-50 amino acids downstream of this histidine. Although transferase has a Glu278-Tyr-Ile sequence characteristic of region III in DT, Glu278 was not critical for activity. In an alternative region III containing Glu238-Glu239-Glu240, Glu238 and Glu240 but not Glu239 were critical. Glu240 aligned with critical glutamates in DT, Pseudomonas exotoxin, and C3 transferase. Thus, the mammalian ADP-ribosyltransferases have motifs similar to toxin ADP-ribosyltransferases, suggesting that these sequences are important in ADP-ribose transfer reactions.

Adenosine Diphosphate Ribose↗
PubMed1995

ADP-ribosyltransferase type A from turkey erythrocytes modifies actin at Arg-95 and Arg-372.

Turkey erythrocyte ADP-ribosyltransferase A catalyzes the transfer of ADP-ribose from NAD to both monomeric and polymeric skeletal muscle alpha-actin with the incorporation of 2 mol of ADP-ribose per mol of actin. In contrast, Clostridium perfringens iota toxin ADP-ribosylates only G-actin, with modification at arginine-177 [Vandekerckhove, J., et al. (1987) FEBS Lett. 255, 48-42]. Transferase A-catalyzed modifications are sensitive to 0.5 M neutral hydroxylamine, consistent with the arginine side chain modification. Radiolabeled peptides ADP-ribosylated by transferase A were generated by tryptic digestion and purified by reversed phase high-performance liquid chromatography. Amino acid sequence and molecular mass analysis identified the ADP-ribosylation sites as Arg-95 and Arg-372 of actin; both residues are located within subdomain-1 of the actin 3D structure [Kabsch, W., et al. (1990) Nature 347, 37-44]. ADP-ribosylation did not affect cytochalasin D-stimulated G-actin ATPase, the binding of actin to DNase I or to gelsolin, or the ability of actin to polymerize. Following ADP-ribosylation, however, a prolonged delay in polymerization was observed, consistent with a decreased rate of nucleation.

Actins↗
PubMed1995

Different ARF domains are required for the activation of cholera toxin and phospholipase D.

ADP-ribosylation factors (ARFs), initially described as activators of cholera toxin ADP-ribosyltransferase activity, regulate intracellular vesicular membrane trafficking and stimulate a phospholipase D (PLD) isoform. ARF-like (ARL) proteins are structurally related to ARFs but do not activate cholera toxin and have relatively little effect on PLD. A new human ARL gene termed hARL1, which shares 57% amino acid identity with hARF1, was identified using a polymerase chain reaction-based cloning method. To determine whether different structural elements are responsible for the activation structural elements are responsible for the activation of the A subunit of cholera toxin and PLD, chimeric proteins were constructed by switching the amino-terminal 73 amino acids of ARF1 and ARL1. The recombinant rL73/F protein, in which the amino-terminal 73 amino acids of ARL1 replaced those of ARF1, activated the A subunit of cholera toxin, whereas the rF73/L protein, in which the NH2-terminal 73 amino acids of ARF1 replaced those of ARL1, was inactive. The two chimeric proteins had quite opposite effects on PLD activity. rF73/L activated PLD as effectively as rARF1, whereas rL73/F protein activated PLD only slightly. It appears that the amino-terminal region of ARF1 is not critical for its action as a GTP-dependent activator of cholera toxin, whereas it is necessary for activation of the putative effector enzyme, PLD.

ADP-Ribosylation Factor 1↗