A role of calcyclin, a Ca(2+)-binding protein, on the Ca(2+)-dependent insulin release from the pancreatic beta cell

Exocytosis is an important example of cell activation. Ca2+ and calcium-binding proteins are considered to modulate signal transduction in exocytosis. We examined the role of calcyclin, calcium-binding protein, in the stimulus-secretion coupling in pancreatic beta cells. The presence of calcyclin in these cells was demonstrated immunologically. We permeabilized rat pancreatic islets with streptolysin-O and examined the effects of calcyclin on insulin release. The Ca(2+)-stimulated insulin release was enhanced by calcyclin, in a dose-dependent manner, whereas this calcium-binding protein had no effect on insulin release from islets in low Ca2+ buffer or from the islets not subjected to the streptolysin-O treatment. Calgizzarin, another member of the S-100 protein family, had no apparent effect on the Ca(2+)-stimulated secretion under parallel conditions. An anticalcyclin antibody suppressed the increase in insulin release induced by calcyclin. We propose that calcyclin may be involved in signal transduction of the Ca(2+)-induced release of insulin.

Lipocortin I is not accessible for protein kinase C bound to the cytoplasmic surface of the plasma membrane in streptolysin-O-permeabilized pig granulocytes

We previously observed a 38 kDa protein that was a major protein component of the cytosolic extract of pig granulocytes and the dominant substrate of protein kinase C at supra-physiological Ca2+ concentrations. The purified 38 kDa protein itself required Ca2+ to be phosphorylated by protein kinase C. Now we demonstrate that this protein, which is also present in human granulocytes, is identical to lipocortin I. The identification is based on the chromatographic properties and immunoblot of the purified protein which is also a good substrate for tissue transglutaminase. Phosphorylation of lipocortin I by protein kinase C was investigated in granulocytes permeabilized with streptolysin-O. At physiological intracellular Ca2+ concentrations lipocortin I was not phosphorylated at all. At supra-physiological Ca2+ concentrations (0.5 mM), lipocortin I was also not phosphorylated when protein kinase C was translocated to the membrane by treatment of the cells with phorbol myristate acetate. Its phosphorylation was detectable only in control experiments when protein kinase C was activated in the cytosol by the addition of dioleoylglycerol and phosphatidylserine to the permeabilized cells. The data presented show that, in permeabilized granulocytes, Ca(2+)-lipocortin is not formed at physiological Ca2+ concentrations, and at supra-physiological Ca2+ concentrations the Ca(2+)-lipocortin I is not accessible to protein kinase C bound to the cytoplasmic surface of the plasma membrane.

Characterization of the budding compartment of mouse hepatitis virus: evidence that transport from the RER to the Golgi complex requires only one vesicular transport step

Mouse hepatitis coronavirus (MHV) buds into pleomorphic membrane structures with features expected of the intermediate compartment between the ER and the Golgi complex. Here, we characterize the MHV budding compartment in more detail in mouse L cells using streptolysin O (SLO) permeabilization which allowed us to better visualize the membrane structures at the ER-Golgi boundary. The MHV budding compartment shares membrane continuities with the rough ER as well as with cisternal elements on one side of the Golgi stack. It also labeled with p58 and rab2, two markers of the intermediate compartment, and with PDI, usually considered to be a marker of the rough ER. The membranes of the budding compartment, as well as the budding virions themselves, but not the rough ER, labeled with the N-acetyl-galactosamine (GalNAc)-specific lectin Helix pomatia. When the SLO-permeabilized cells were treated with guanosine 5'-(3-O-thio)triphosphate (GTP gamma S), the budding compartment accumulated a large number of beta-cop-containing buds and vesicular profiles. Complementary biochemical experiments were carried out to determine whether vesicular transport was required for the newly synthesized M protein, that contains only O-linked oligosaccharides, to acquire first, GalNAc and second, the Golgi modifications galactose and sialic acid. The results from both in vivo studies and from the use of SLO-permeabilized cells showed that, while GalNAc addition occurred under conditions which block vesicular transport, both cytosol and ATP were prerequisites for the M protein oligosaccharides to acquire Golgi modifications. Collectively, our data argue that transport from the rough ER to the Golgi complex requires only one vesicular transport step and that the intermediate compartment is a specialized domain of the endoplasmatic reticulum that extends to the first cisterna on the cis side of the Golgi stack.

Glucocorticoid-regulated trafficking of mouse mammary tumor virus proteins in permeabilized hepatoma cells. Requirements of intracellular membrane transport for maturation of the cytoplasmic phosphorylated polyprotein

Glucocorticoids coincidentally regulate the localization of mouse mammary tumor virus (MMTV) glycoproteins and maturation of viral phosphoproteins in viral infected rat hepatoma cells. To test for a functional interaction between MMTV transmembrane glycoproteins and cytoplasmic phosphoproteins, the bacterial cytolysin streptolysin-O was utilized to selectively permeabilize the plasma membrane and reconstitute exocytic trafficking. Streptolysin-O-permeabilized M1.54 cells pretreated with glucocorticoids retained the capability for proteolytic processing, cell surface delivery, and externalization of MMTV glycoproteins as determined by immunoprecipitation and immunofluorescence microscopy. The efficient maturation of MMTV phosphoproteins indicated that these viral proteins are properly transported near or to the plasma membrane in permeabilized cells. These maturation events in semi-intact cells were dependent on the addition of cell cytosol and were specifically inhibited by the membrane impermeant GTP analog guanosine 5'3-O-(thio)triphosphate, an agent known to impede vesicular transport of membrane proteins, but which has not previously been shown to alter cytoplasmic protein maturation or transport. The addition of anti-MMTV antibodies directed against the cytoplasmic domain of the glycoprotein precursor to transport competent semi-intact M1.54 cells resulted in the dramatic inhibition of both MMTV glycoprotein and phosphoprotein maturation. These results were not obtained using either preimmune sera or antiserum specific for the luminal portion of the glycoprotein precursor. Our findings suggest that the functional interaction of cytosolic MMTV phosphoproteins with the cytoplasmic domain of the viral membrane glycoprotein is required for the efficient transport and processing of each class of proteins in glucocorticoid-treated cells and provides the first evidence for the involvement of vesicular transport in the delivery and maturation of cytoplasmic viral proteins at the plasma membrane or the pericellular region.

Stimulation of insulin release from permeabilized HIT-T15 cells by a synthetic peptide corresponding to the effector domain of the small GTP-binding protein rab3

A synthetic peptide (rab3AL) corresponding to the effector domain of rab3, a small GTP-binding protein, stimulated basal and potentiated Ca(2+)- as well as GTP gamma S-evoked insulin secretion about 2-fold from streptolysin-O permeabilized HIT cells. This effect was specific, since the analogous peptides of ras or rab1 did not affect the exocytotic event. The more than additive effect of rab3AL on Ca2+ or GTP gamma S stimulation indicates a distinct mode of action of the peptide. The partial loss of cytosolic proteins from permeabilized cells was accompanied by a faster run-down of the secretory response to Ca2+ than the one to GTP gamma S. The persistent effect of rab3AL under these conditions points to a membrane localization of its target. These results suggest that rab3 and its effector are involved in the regulation of insulin secretion.

Guanine nucleotides activate multiple signaling pathways in permeabilized gastric chief cells. Evidence for GTP gamma S-induced calcium-independent pepsinogen secretion

Nonhydrolyzable guanine nucleotide analogues were used to evaluate the role of guanine nucleotide binding (G) proteins in regulating pepsinogen secretion from streptolysin O-permeabilized chief cells from guinea pig stomach. In the presence of 100 nM calcium, 100 microM guanosine 5'-(beta,gamma-imido)triphosphate or guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) caused a 2- to 4-fold increase in pepsinogen secretion. GTP gamma S stimulated secretion in the absence of calcium (up to 10 mM EGTA). With or without added calcium, GTP analogues caused a 2- to 3-fold increase in cAMP, whereas guanosine 5'-O-2-(thio)diphosphate and calcium alone had no effect on cAMP levels. GTP analogue-induced activation of phospholipase C was evidenced by a calcium-independent increase in cytidine diphospho-1,2-diacylglycerol levels (50% above basal). Phorbol ester- and GTP gamma S-stimulated phosphorylation of a 72-kDa acidic protein was abolished by an inhibitor of protein kinase C (CGP 41251). However, GTP gamma S-induced pepsinogen secretion was only partially inhibited by adding CGP 41251 or a protein kinase C inhibitor peptide. These results indicate that guanine nucleotides activate major signaling pathways in gastric chief cells. Nevertheless, GTP gamma S can induce pepsinogen secretion independently of changes in calcium, cAMP, or activation of protein kinase C.

Calcium-induced secretion from permeabilized rat mast cells: requirements for guanine nucleotides

Cells used in this work were permeabilized by streptolysin-O and then washed to remove freely soluble components. The secretory responsiveness of these cells to various combinations of calcium, MgATP and guanine nucleotide was characterized and in most respects was found to be similar to that of the metabolically inhibited (unwashed) cells. The content of adenosine and guanine nucleotides, which remain within the permeabilized cells after washing, was estimated as 0.83 and 0.12 mM (extrapolated to intact cells), which constitutes 18 and 25%, respectively, of the total nucleotide content of mast cells. High (> mM) concentrations of MgATP, required for the calcium-induced secretion, were reduced to microM levels by suboptimal concentrations of GTP, which also markedly increased both the rate and extent of the response. Similarly, microM concentrations of MgATP reduced the requirements of the calcium-dependent secretion for GTP. The synergy of the GTP and ATP effects suggests that, together, the two nucleotides can maintain a pool of free GTP, presumably as a result of transphosphorylation from ATP to GDP. Thus, MgATP may work by transphosphorylating the endogenous GDP. However, neither GTP nor GTP-gamma-S were effective as substitutes for MgATP in the calcium-induced secretion, particularly that from metabolically inhibited cells. This indicates that MgATP does not act simply by providing GTP but is needed to maintain a phosphorylated state of the system. The synergistic effects of ATP and GTP were observed only in the presence of calcium. To test whether calcium/MgATP-induced secretion requires an activated G protein, the effects of G-protein inactivators were studied. GDP, deoxy GDP and GDP-beta-S exerted differing degrees of inhibition on secretory responses induced by various combinations of effectors. The response to calcium/MgATP was less sensitive to these inhibitors than that to GTP-gamma-S (with or without calcium). However, all three 'inhibitors' were also capable of stimulating calcium/MgATP-dependent secretion, indicating a transphosphorylation, producing GTP, dGTP and GTP-beta-S. Thus, in the absence of any specific inhibitors for either G proteins or the transphosphorylation reaction, the degree of dependence of the calcium-induced secretion on a G protein remains unclear.

Calcium and GTP-gamma-S as single effectors of secretion from permeabilized rat mast cells: requirements for ATP

Treatment with metabolic inhibitors and addition of exogenous MgATP exerted different effects on secretion from streptolysin-O-permeabilized mast cells, responding to calcium and GTP-gamma-S as single effectors (i.e., independently of each other). These effects were also strongly dependent on the experimental conditions. Thus cells, triggered by Ca2+ at the time of permeabilization, did not require MgATP, but after metabolic inhibition rapidly became absolutely dependent on its provision, requiring high (> mM) concentrations. AMP-PNP was not effective. After longer treatment with metabolic inhibitors, the absolute dependence on MgATP was also exhibited by cells responding to dual effectors (i.e., Ca2+ and GTP-gamma-S applied together). In contrast, calcium independent secretion due to GTP-gamma-S was more resistant to metabolic inhibition, exhibiting no absolute requirements for MgATP. Once the responsiveness to GTP-gamma-S had been lost, it could not be restored by addition of MgATP. MgATP, in fact, inhibited the response of permeabilized cells to GTP-gamma-S. This effect could be mimicked by AMP-PNP. When permeabilized cells were washed before triggering, MgATP (0.1-1 mM concentration range) was no longer inhibitory but stimulatory. These differences between Ca(2+)- and GTP-gamma-S-induced responses indicate that ATP utilization is essential to the calcium, but not to the guanine nucleotide, pathway to secretion. The rate of the response to calcium/MgATP was much slower in the absence than in the presence of GTP-gamma-S. The onset of secretion occurred after an initial delay. This lag phase was abolished by addition of GTP-gamma-S, suggesting that a GTP-binding protein may control a reaction which constitutes a rate-limiting step in the secretory process.

Import of firefly luciferase into peroxisomes of permeabilized Chinese hamster ovary cells: a model system to study peroxisomal protein import in vitro

A model system for the study of in vitro peroxisomal protein import is described. Chinese hamster ovary (CHO) cells were permeabilized by the bacterial toxin streptolysin O (SLO) and their peroxisomes thus became accessible for a model import protein. Firefly luciferase (FL), which was previously shown to be imported into mammalian peroxisomes in vivo, was used as the reporter protein. When SLO-permeabilized CHO cells were incubated with FL in the presence of an ATP-regenerating system, import of FL could be documented by immunofluorescence staining of the cells with monospecific anti-FL antiserum. FL import increased with time and was dependent on temperature and the presence of hydrolysable ATP, which could not be replaced by GTP. The model system functioned reproducibly and should be of use for investigating fundamental questions on the mechanism of peroxisomal protein import.

Chromosome damage induced by nanomolar concentrations of bleomycin in porated mammalian cells

We have examined chromosome damage caused by a wide range of bleomycin (BLM) concentrations in Chinese hamster ovary (CHO-K1) cells reversibly porated by the bacterial cytotoxin streptolysin-O (SLO). Chromosome damage was measured using the micronucleus cytokinesis block technique (employing cytochalasin-B). Treatment of exponentially growing cells with 0.045 IU/mL SLO for 5 min resulted in up to a thousand-fold and a million-fold increase in biological effectiveness, compared to treatment in the absence of SLO for 24 hr and 5 min, respectively. Increases in micronuclei of 4-5 times background level were observed after only 5 min exposure to the drug in the presence of SLO at doses as low as 100 pg/mL (approximately 70 pmol/L). These results indicate that the use of SLO may facilitate the treatment of cells with BLM for periods of time resembling acute exposure to ionizing radiations.

CD3 and CD2 antigen-mediated CD3 gamma-chain phosphorylation in permeabilized human T cells. Regulation by cytosolic phosphatases

The role of cytosolic and membrane-associated phosphatases in regulating dephosphorylation of the CD3 antigen gamma-chain has been investigated using streptolysin-O-permeabilized T lymphoblasts and Jurkat T leukaemia cells. Permeabilization of T cells caused a rapid extrusion of cytosolic type 2A phosphatases, but a membrane-associated phosphorylase phosphatase activity remained inside the cells. This activity had the properties characteristic of type 2A phosphatases, being resistant to inhibition by type 1 phosphatase inhibitors, though it was inhibited in a time-dependent manner by ATP or by non-hydrolysable ATP analogues, but not by GTP, CTP, ITP or PPi. The membrane-associated type 2A phosphatase in permeabilized cells did not dephosphorylate the CD3 antigen gamma-chain, suggesting that cytosolic phosphatases dephosphorylate the gamma-chain in situ. Cross-linking the CD2 and CD3 antigens with a bivalent monoclonal antibody in the absence of cytosolic phosphatases induced marked phosphorylation of the CD3 gamma-chain, immunoprecipitated using a novel gamma-chain peptide analogue directed antiserum (TG1). Phosphorylation was inhibited by a protein kinase C (PKC) pseudosubstrate inhibitor, indicating that CD2/CD3-induced gamma-chain phosphorylation is a PKC-mediated event. Activation of T cells either with phorbol 12,13-dibutyrate or by CD2-CD3 cross-linking caused [32P]Pi incorporation into the same gamma-chain Ser residues. The site-mapping data suggested that PKC in situ may incorporate phosphate at the CD3 gamma-chain Ser-123 and Ser-126 residues, but that phosphate is rapidly lost from Ser-123 by cytosolic phosphatase action. Our findings underline the importance of the dual actions of kinases and phosphatases as potential regulators of T cell antigen-receptor complex function.

G-proteins mediate inhibition and activation of Ca(2+)-induced exocytosis from SLO-permeabilized peptidergic nerve endings

In SLO-permeabilized isolated nerve endings from the rat neurohypophysis, GTP, guanosine 5'[y-thio]triphosphate (GTPyS) and guanosine 5'(beta y-imido]triphosphate (GMPPNP) inhibit the Ca(2+)-evoked vasopressin release. Pretreatment with pertussis toxin enhances the inhibitory effects of both GTP-analogues. Omission of Mg2+ overcomes the effect of GMPPNP and reverses the inhibitory effect of GTP and GTPyS. In the absence of Mg2+, GTP and GTPyS now potentiate Ca(2+)-evoked secretion.

Properties of protein kinase C associated with nuclear membranes

To study signal transduction directed towards the cell nucleus and at the nuclear membranes, we investigated the association of protein kinase C (PKC) with nuclear membranes obtained from nuclei isolated from bovine brain. By use of phorbol-ester-binding assays, significant amounts of PKC could be demonstrated in nuclei and nuclear membranes. Nuclear membranes are shown to be able to activate purified PKC. The PKC endogenously present in nuclear membranes appears to be a so-called 'membrane-inserted' form: it is permanently active, still binds phorbol ester, but its activity is no longer dependent on Ca2+ and cannot be activated by phorbol ester. On the other hand, this form of PKC can be inhibited by specific PKC inhibitors. By using histone HIIIS and a specific peptide substrate, it could be shown that after extraction with Triton X-100 the PKC can be stimulated by phospholipid again. Immunoblot analysis with isoenzyme-specific antibodies revealed that the alpha- and gamma-isoenzymes, but not the beta-isoenzyme, are associated with membranes derived from brain nuclei.

The nuclear membrane prevents replication of human G2 nuclei but not G1 nuclei in Xenopus egg extract

We have used synchronized HeLa cells to investigate the role of the nuclear membrane in preventing rereplication in a single cell cycle. Nuclei were prepared with intact nuclear membranes using streptolysin-O or digitonin and assayed for replication in Xenopus egg extracts. Intact G1 nuclei replicate semiconservatively, but intact G2 nuclei do not replicate in egg extract. However, permeabilizing the nuclear membranes of G2 nuclei by treatment with NP-40 allows them all to replicate in egg extract under cell cycle control, suggesting that integrity of the nuclear membrane is required to distinguish G2 from G1 human nuclei and to prevent rereplication within a single cell cycle. The results are discussed in terms of the previously proposed licensing factor model.

Retrograde transport from the Golgi region to the endoplasmic reticulum is sensitive to GTP gamma S

The involvement of GTP-binding proteins in the intracellular transport of the secretory glycoprotein alpha 1-antitrypsin was investigated in streptolysin O-permeabilized HepG2 cells. This permeabilization procedure allows ready access to the intracellular milieu of the membrane-impermeant, nonhydrolyzable GTP analog GTP gamma S. In streptolysin O-permeabilized HepG2 cells, the constitutive secretory pathway remains functional and is sensitive to GTP gamma S. Exposure of HepG2 cells to brefeldin A resulted in redistribution of Golgi-resident glycosyltransferases (including both alpha 2----3 and alpha 2----6 sialyltransferases) to the ER. This redistribution was sensitive to GTP gamma S. Our results suggest that GTP-binding proteins are involved in the regulation not only of the anterograde, but also of the retrograde, pathway.

[Focal infection in dentistry: the in vitro specific lymphocyte blast test]

The authors used an "in vitro" test of specific blastogenic response to streptococcal antigens, to evidence a sensitivity status in chronic odontogenic infections. The authors didn't find always a direct correlation between specific lymphoproliferative response and haematologic tests but found a good correlation with clinics. They conclude an increased value of specific lymphoproliferative response as predictive meaning of metafocal diseases.

Rapid release of bound glucose-6-phosphate dehydrogenase by growth factors. Correlation with increased enzymatic activity

Epidermal growth factor (EGF), a mitogen for renal proximal tubule cells, activated the hexose monophosphate (HMP) shunt in renal proximal tubule cells (Stanton, R. C., and Seifter, J. L. (1988) Am. J. Physiol. 254, C267-C271). We therefore evaluated the effect of EGF on the HMP shunt enzymes glucose 6-phosphate dehydrogenase (G6PD, the rate-limiting enzyme) and 6-phosphogluconate dehydrogenase. Rat renal cortical cells (RCC) were incubated with either EGF or platelet-derived growth factor (PDGF) and then assayed for G6PD and 6-phosphogluconate dehydrogenase activities. EGF and PDGF increased G6PD activity by 25 and 27% respectively. Although phorbol myristate acetate (PMA), ionomycin, PMA + ionomycin, and 8-bromo-cyclic AMP had no significant effect on the activity, a 5-min preincubation with PMA potentiated the activation of G6PD by PDGF. Growth factor activation of G6PD was also seen in a fibroblast and epithelial cell line. None of the agents affected 6-phosphogluconate dehydrogenase activity in the RCC or in the cell lines. Further exploration into a possible mechanism for G6PD activation revealed that growth factors caused release of G6PD from a structural element within the cell. Streptolysin O permeabilization of RCC did not cause significant release of G6PD. However, within 1 min of addition of EGF or PDGF to permeabilized cells, G6PD was released into the cell supernatant. The nonhydrolyzable analog of GTP, guanosine 5'-O-(thiotriphosphate), caused a similar release of G6PD. Preincubation with pertussis toxin or guanyl-5'-yl thiophosphate inhibited the PDGF but not the EGF effect. Although the data do not establish a definitive proof linking G6PD release and G6PD activation, these results suggest that they are related. Thus, growth factor stimulation of the HMP shunt likely occurs by a novel mechanism associated with release of bound G6PD.

Transport of influenza HA from the trans-Golgi network to the apical surface of MDCK cells permeabilized in their basolateral plasma membranes: energy dependence and involvement of GTP-binding proteins

A procedure employing streptolysin O to effect the selective permeabilization of either the apical or basolateral plasma membrane domains of MDCK cell monolayers grown on a filter support was developed which permeabilizes the entire monolayer, leaves the opposite cell surface domain intact, and does not abolish the integrity of the tight junctions. This procedure renders the cell interior accessible to exogenous macromolecules and impermeant reagents, permitting the examination of their effects on membrane protein transport to the intact surface. The last stages of the transport of the influenza virus hemagglutinin (HA) to the apical surface were studied in pulse-labeled, virus-infected MDCK cells that were incubated at 19.5 degrees C for 90 min to accumulate newly synthesized HA in the trans-Golgi network (TGN), before raising the temperature to 35 degrees C to allow synchronized transport to the plasma membrane. In cells permeabilized immediately after the cold block, 50% of the intracellular HA molecules were subsequently delivered to the apical surface. This transport was dependent on the presence of an exogenous ATP supply and was markedly inhibited by the addition of GTP-gamma-S at the time of permeabilization. On the other hand, the GTP analogue had no effect when it was added to cells that, after the cold block, were incubated for 15 min at 35 degrees C before permeabilization, even though at this time most HA molecules were still intracellular and their appearance at the cell surface was largely dependent on exogenous ATP. These findings indicate that GTP-binding proteins are involved in the constitutive process that effects vesicular transport from the TGN to the plasma membrane and that they are charged early in this process. Transport of HA to the cell surface could be made dependent on the addition of exogenous cytosol when, after permeabilization, cells were washed to remove endogenous cytosolic components. This opens the way towards the identification of cell components that mediate the sorting of apical and basolateral membrane components in the TGN and their polarized delivery to the cell surface.

Changes in the state of actin during the exocytotic reaction of permeabilized rat mast cells

The major part of mast cell actin is Triton-soluble and behaves as a monomer in the DNase I inhibition assay. Thus, actin exists predominantly in monomeric or short filament form, through filamentous actin is clearly apparent in the cortical region after rhodamine-phalloidin (RP) staining. The minimum actin content is estimated to be approximately 2.5 micrograms/10(6) cells (cytosolic concentration approximately 110 microM. After permeabilization of mast cells by the bacterial cytolysin streptolysin-O, approximately 60% of the Triton-soluble actin leaks out within 10 min. However, the staining of the cortical region by RP remains undiminished, and the cells are still capable of exocytosis when stimulated by GTP-gamma-S together with Ca2+. In the presence of cytochalasin E the requirement for Ca2+ is decreased, indicating that disassembly of the cytoskeleton may be a prerequisite for exocytosis. This disassembly is likely to be controlled by Ca2(+)-dependent actin regulatory proteins; their presence is indicated by a Ca2(+)-dependent inhibition of polymerization of extraneous pyrene-G-actin by a Triton extract of mast cells. The effect of cytochalasin E on secretion is similar to that of phorbol myristate acetate, an activator of protein kinase C; both agents enhance the apparent affinity for Ca2+ and cause variable extents of Ca2(+)-independent secretion. Exposing the permeabilized cells to increasing concentrations of Ca2+ caused a progressive decrease in F-actin levels as measured by flow cytometry of RP-stained cells. In this respect, both cytochalasin E and phorbol ester mimicked the effects of calcium. GTP-gamma-S was not required for the Ca2(+)-dependent cortical disassembly. Thus, since conditions have not yet been identified where secretion can occur in its absence, cortical disassembly may be essential (though it is not sufficient) for exocytosis to occur.

Inhibition of noradrenaline release by antibodies to B-50 (GAP-43)

Protein kinase C (PKC) is believed to have a crucial role in synaptic transmitter release and long-term potentiation. An important substrate of PKC in the brain is the neuron-specific presynaptically localized protein B-50 (also termed GAP-43, F1, pp46 or P-57). B-50 has been implicated in the regulation of polyphosphoinositide metabolism and calmodulin binding, and in the mechanisms of neurite outgrowth, long-term potentiation and transmitter release. It is still unknown, however, whether B-50 (and/or its phosphorylation) is essential to any of these processes. Here we report the results of studies in which antibodies to B-50, which interfere with B-50 phosphorylation, were introduced into rat cortical synaptosomes that were permeabilized with streptolysin-O (SL-O). We found that the release of [3H]noradrenaline, induced by increasing the Ca2+ concentration in the buffer, is inhibited completely by the antibodies. These results provide the first demonstration of a causal relationship between the PKC substrate B-50 and the release of neurotransmitter.

Comparison of antibody titres to streptococcal extracellular antigens

Antibody titres were measured against extracellular products of group A beta haemolytic streptococci. Comparison of the titres obtained with antistreptolysin O (ASO), streptozyme, antideoxyribonuclease-B (ADN-B), antinicotinamide adenine dinucleotidase (ANAD), antihyaluronidase (ASH), and antistreptokinase (ASK), in 412 human serum specimens with different categories were tested. The results obtained were as follows: the streptozyme test was in good correlation with ASO, and can detect more specimens with elevated antibody titres than any other single test, but was not as good as the combination of any other tests like ASO and ADN-B. For determination of streptococcal infection, it is necessary to test for more than one antibody. Streptozyme test is valuable screening in combination with ASO, for those laboratories depending on ASO alone.

A protein kinase C pseudosubstrate peptide inhibits phosphorylation of the CD3 antigen in streptolysin-O-permeabilized human T lymphocytes

Activation of human T lymphocytes leads to the phosphorylation of the CD3-antigen gamma polypeptide. We have investigated a possible role for protein kinase C (PKC) in mediating this phosphorylation event by using T cells permeabilized with streptolysin-O in the presence of 120 mM-K+ buffers containing Ca2+-EGTA. The gamma-chain was phosphorylated by [gamma-32P]ATP in permeabilized T lymphoblasts in the presence of phorbol 12,13-dibutyrate (Pdbu) or phytohaemagglutinin (PHA). Ca2+ alone in the range 0.5-1.0 microM also induced gamma-chain phosphorylation in some T-lymphoblast preparations; that in Jurkat-6 cells occurred at lower concentrations (50-500 nM). Two experimental approaches were used to investigate the possible involvement of PKC. Firstly, when permeabilization was carried out in buffer lacking free Ca2+, PKC was lost from the cells, and gamma-chain phosphorylation could then no longer be induced on subsequent addition of Pdbu or PHA in 400 nM-Ca2+, or 800 nM-Ca2+ alone, to permeabilized cells. However, when permeabilization was carried out in the presence of these three agents, PKC was translocated to intracellular membranes, and subsequent addition of [gamma-32P]ATP to these cells then resulted in gamma-chain phosphorylation. In the second approach, induction of gamma-chain phosphorylation by Pdbu, 1-oleoyl-2-acetylglycerol, 1,2-diolein, PHA or Ca2+ alone was effectively blocked by permeabilizing T cells in the presence of a PKC pseudosubstrate peptide (50 microM). Pseudosubstrate concentrations in the range 7-20 microM inhibited gamma-chain phosphorylation by 50%. In contrast, addition of four other 'irrelevant' basic peptides (50 microM) did not result in detectable inhibition, and 50 microM-pseudosubstrate did not inhibit the phosphorylation of 17 other polypeptides isolated from permeabilized T cells. These data suggest that Pdbu-, 1,2-diacylglycerol-, PHA- and Ca2+-induced phosphorylation of the CD3-antigen gamma chain in permeabilized T cells is mediated by PKC.

Reactivation of streptolysin S by oligonucleotide

Oligonucleotide-streptolysin S complex inactivated by alkali treatment remains nonhemolytic, even after acidification and mixing with intact carrier oligonucleotide rich in guanyl residue. Upon dehydration, however, the inactive streptolysin S-oligonucleotide mixture turned to be hemolytic, and this reactivation of the hemolysin was promoted by treatment with guanidine hydrochloride. After alkaline hydrolysis, streptolysin S was freed from nucleotide moiety, by gel filtration through a Sephadex G-50 column. From this nonhemolytic apotoxin as well, active streptolysin S complex was reconstructed upon dehydration with the carrier.

[Serologic diagnosis of streptococcal diseases. Ulterior data on the comparison of 2 methods (streptozyme and antistreptolysin O]

Increasingly thorough analysis of the antigen structures of Group A beta-haemolytic streptococci has revealed the presence of antigen components with differentiated immune responses in relation to common streptococcal conditions. It is therefore extremely useful in laboratory practice to have a multiple antigen that reveals the immune response to a streptococcal infection so that we can study the serological behaviour of individual streptococcal pictures with their complications and sequelae. Research conducted to date indicates that the streptozyme test can explore the five main streptococcal isoenzymes both for rapid screening and for the quantification of the degree of antibody response. This is confirmed by the results obtained by numerous Authors over the past 15 years, results that demonstrate the high sensitivity of STZ (Streptozyme) at antibody level that single antibody reactions are apparently not capable of revealing. The polyvalent antigen represented by STZ seems to be the best tool for the demonstration of responses to the individual isoenzymes of the very numerous streptococcal strains in circulation (Group A, C and G beta-haemolytics). The possibility of using microtiter techniques for serum assays is also emphasised. These techniques have given repeatable results and are also easy to read.

Streptococcal antibody tests in rheumatic fever

Although the incidence of rheumatic fever has declined significantly over the last decade, testing for antibodies to streptococcal extracellular enzymes maintains an important role in differentiating this disease from others with similar characteristics. Detection of antibodies to streptolysin O and DNase-B remain the more popular single antibody tests while the streptozyme test, which detects antibodies to five distinct streptococcal extracellular products, has been increasingly used in recent years as a screening test. Several new procedures detecting antibodies to different somatic antigens have been developed, the most promising of which seem to be anti-Group A carbohydrate tests. Because antibodies to the group A carbohydrate remain for several years in patients with persistent rheumatic valvular disease, this test should aid in the differentiation of rheumatic from non-rheumatic heart disease.

Purified -SH-activated toxins (streptolysin O, alveolysin): New tools for determination of platelet enzyme activities

The purpose of this study was to examine the lytic effect on human platelet preparations (washed, gel-filtered and dextran-isolated) of two sulfhydryl-activated bacterial protein toxins, streptolysin 0 and and alveolysin, and to compare their efficacy with that of other disruptive procedures (freezing and thawing, ultrasonic, mechanical, or nystatin-toluene treatment) as a method for the determination of various platelet enzyme activities. The enzymes assayed were alkaline and acid phosphatases, monoamine oxidase, phenolsulfotransferase, N-acetyltransferase, hydroxyindole-O-methyltransferase, glutathione peroxidase and lactate dehydrogenase. In all cases, the lowest activities were found after freezing and thawing and/or ultrasonic disruption. The highest activities were always observed in the platelet lysates obtained after toxin, and in some instances after nystatin-toluene treatment. Intermediate values were obtained for mechanical disruption. The -SH-activated cytolysins thus appear to be appropriate and gentle tools for the assay of platelet enzymes when compared to the physical or chemical procedures generally employed.

Effect of streptococcal extracellular nuclease on the carrier activity of RNA for streptolysin S

Upon digestion with a streptococcal extracellular nuclease, yeast RNA yielded acid-insoluble core having increased carrier activity for streptolysin S. The carrier activity was found in minor fractions of the core which were eluted from a DEAE-cellulose column at higher salt concentrations. Upon gel filtration through a Sephadex G-75 column, the effective component (Fr. I) was eluted earlier than bulk oligonucleotides (Fr. II). Nucleotide composition (in mol %) of Fr. I was AMP: 21.8; GMP: 55.1; CMP: 8.2; UMP: 14.9, whereas that of Fr. II was AMP: 38.0; GMP: 33.1; CMP: 8.0; UMP: 20.9. Chromatographic patterns of SLS complex induced by Fr. I were similar to those of the toxin formed in the presence of active fraction prepared from RNase I core. Hemolytic activity of the latter complex was, like the former, unaffected by streptococcal nuclease treatment. The carrier activity of DNA digested with the nuclease was also investigated.

[Comparative evaluation of several methods of determining anti-streptolysin O]

The Authors have carried out some experiences on four tests for the detection of anti O streptolysin, determining in 210 samples of sera: 1. the antistreptolysin titer according to Rantz and Randall; 2. the antistreptolysin titer according to the latex reaction; 3. five different antistreptococcal antibodies (ASO, ASK, ASHA, ADN-aseB, NAD-ase) with a rapid multi-purpose test for a simultaneous detection; 4. the antistreptolysin titer according to Aso Quantum method. The results obtained on the 210 samples of sera were compared. The relationship between the four methods were examined.

Interaction of streptolysin O from Streptococcus pyogenes and theta-toxin from Clostridium perfringens with human fibroblasts

The membrane-damaging properties on human diploid embryonic lung fibroblasts of streptolysin O (from Streptococcus pyogenes) and theta-toxin (from Clostridium perfringens) were compared. The results are consistent with the suggested mechanism for hemolysis by streptolysin O involving one fixation site and one lytic site of this cytolysin. However, the membrane-damaging activity of the two toxins differed with respect to (i) relative cytolytic activity on human diploid lung fibroblasts compared with that on sheep erythrocytes, (ii) binding to the fibroblast membrane, (iii) activity at 0 degrees C, (iv) membrane repair after more than 30 min, and (v) effect on influx of amino acids. It is concluded that the mechanism of membrane damage caused by theta-toxin differs from that of cytoplasmic membrane. These results question the current concept that all thiol-activated, cholesterol-inactivated bacterial toxins are similar both structurally and functionally.

The sensitivity and specificity of an agglutination test for antibodies to streptococcal extracellular antigens: a quantitative analysis and comparison of the Streptozyme test with the anti-streptolysin O and anti-deoxyribonuclease B tests

As a part of studies of streptococcal infections of the upper respiratory tract, sera from 142 individuals (mean age 11.9 years) with signs and symptoms on tonsillitis or pharyngitis and their family contacts were studied to quantitatively evaluate the sensitivity and specificity of the Streptozyme test. We also compared this agglutination test for streptococcal extracellular antibodies with the antistreptolysin O and antideoxyribonuclease B tests. Using different lots of Streptozyme reagent we found evidence suggesting variation in the strength of the reagent from lot to lot. Evaluation of the group specificity of the Streptozyme test suggests that it may not be specific for antibodies to extracellular products of group A streptococci, since a response to this test was seen in individuals with only non-group A strains isolated from their upper respiratory tracts. In patients with group A streptococci isolated from the upper respiratory tract, the quantitative sensitivity of the antibody response as measured by the Streptozyme test is comparable to, but no greater than, the ASO or anti-DNase B tests. Our analysis of upper limits of normal for the Streptozyme test in the study population indicates that previous recommendations for values for elevated titers are too low, especially for predominantly pediatric populations, so that previous reports of patients demonstrating an antibody response to Streptozyme-measured antibodies may include a significant number of patients with "normal" levels. This study indicates the need for both further documentation of standardization of the reagents used in this agglutination test and additional quantitative studies of the response measured by Streptozyme.

Otitis media with effusion: specific antibody activities against exotoxins in middle ear effusions

Findings of recent immunologic studies on otitis media with effusion indicate that antibodies in middle ear effusions can either originate from serum and/or from local production in the middle ear cavity and Eustachian tube. Determination of specific antibody activity of different immunoglobulin classes in effusions and sera against certain bacterial antigens may aid in a better understanding of the pathogenesis of otitis media with effusion. A radioimmunosorbent assay was employed in the present study to determine specific antibody activity against streptolysin or staphylolysin. Although these antibody activities were mainly limited to IgG and IgA class antibodies in effusion as well as in serum, it was also found that SIgA of various types of the effusion possesses the antibody activity against these exotoxins. Findings of this study suggest that a local immunity functions in the middle ear cavity of patients with otitis media with effusions and that bacterial infection may contribute to the development of middle ear effusion in certain cases.

[Serological screening of streptococci. Comparison of 2 methods of slide agglutination, one with streptolysin alone, the other with several enzymes (Streptozymes)]

Using 100 sera randomly selected, the clinical characteristis of which were known, we compared two methods of rapid detection of streptococcal infections by slide agglutination. One was the classical latex test for detection of anti-streptolysin O, the other was the streptozyme test. The latter reagent detects the presence of 5 streptococcal antibodies, anti-streptolysin O, anti-streptokinase, anti-streptohyaluronidase, anti-desoxyribonuclease and anti-nicotinamide-adenine-dinucleotidase. It was found to be more sensitive than the latex test, for antistreptolysin O. Estimations of A.S.K. and A.S.H. confirmed also the greater specificity of the streptozyme test and showed that, thanks to the presence of supplementary enzymes, it may be positive earlier than the A.S.O. latex test. Finally, used as a semi-quantitative method, streptozyme is useful to follow up approximately in the laboratory, the course of streptococcal infections.

[Immunosuppressive effects of operations and their possible limitation (author's transl)]

1. The humoral immunosystem is impaired in those cases of catabolic metabolism in which quantitative and qualitative insufficient alimentation is expected after operation. 2. After cholecystectomies as well as after cardiac surgery with extracorporal circulation a reasonably balanced parenteral nutrition composed of carbohydrates and amino acids would considerably inhibit the changes in the humoral immunity, which is a valuable contribution to the prevention of infection. 3. In our experiments on transformation of lymphocytes after mitogenic stimulation, the depressive effects of operation of the cellular immunity were found to be etiologically more complex than was previously assumed in publications.

Cellular streptolysin S-related hemolysins of group A Streptococcus C203S

Group A streptococci strain C203S, grown in heart infusion broth with 0.3% maltose, produce two cellular hemolysins related to extracellular streptolysin S (SLS). Enzymatic lysis of the streptococci by group C streptococcal phage-associated lysin results in release of low titer, labile hemolysin, which can be stabilized by ribonucleic acid (RNA)-core (RNA preparation from yeast). This labile hemolysin can be detected only after the higher titer cellular streptolysin O is removed by erythrocyte membranes or inactivated by N-ethylmaleimide. The other cellular SLS-related hemolysin is released in a latent state (potential hemolysin) which can be activated to high-titer hemolysin by sonication with RNA-core. The titer of such activated hemolysin depends upon the intensity of sonic energy, duration of sonication, and amount of RNA-core. RNA obtained from the streptococci is far less effective than RNA-core. When the cocci are disrupted by sonication or grinding, potential hemolysin and/or activated form may be released, depending upon the conditions employed. The potential hemolysin material is large and heterogeneous; activation appears to involve, in part, disaggregation or fragmentation. Labile hemolysin, potential hemolysin, and the activated form of potential hemolysin can all be converted to hemolysin having the same hemolytic and physical properties as RNA-core SLS, suggesting that all have the same hemolytic moiety. The presence of glucose in heart infusion broth prevents formation of both potential hemolysin and RNA-core SLS by log-phase cells, whereas addition of glucose to a culture in heart infusion broth with 0.3% maltose stops accumulation of potential hemolysin but does not affect continuation of RNA-core SLS release. These results suggest that potential hemolysin is a cellular precursor to RNA-core SLS.

Lymphocyte transformation in syphilis: an in vitro correlate of immune suppression in vivo?

Suppression of cellular immunity during primary and secondary infection may explain, in part, the unusual clinical evolution of syphilis. We have previously shown that lymphocytes from normal subjects undergo blastic transformation when exposed in vitro to Treponema refringens. This response was suppressed in patients with syphilis. the suppression being unrelated to serum factors. In the present paper we studied lymphocyte response in vitro to T. refringens, T. reiter, and T. pallidum as well as to monilia and trychophytins. The response to these antigens was suppressed in patients with syphilis although the response to phytohemagglutinin. pokeweed mitogen, and streptolysin was normal. These data support the hypothesis that human infection with T. pallidum is followed by a complex interaction between cellular and humoral immunity, the former being suppressed in primary and secondary stages.

[Palatine tonsils and immunity. III. T- and B-lymphocytes in the palatine tonsils of patients with chronic tonsillitis]

Both B- and T-cells are contained in the palatine tonsils of patients suffering from chronic tonsillitis. The former respond by blast-transformation to the in vitro stimulation by the streptococcus and staphylococcus antigens and the latter--to PHA, and produce soluble substances inducing blast-transformation reaction of lymphoid cells of the palatine tonsils under the effect of streptococcus and staphylococcus antigens.

Functional role of cholesterol in infection and autoimmunity

Cholesterol binds to streptolysin O and related bacterial toxins. In normal serum, only a fraction of the cholesterol attached to lipoprotein is available for binding, probably as a cholesterol-peptide complex formed during catabolic breakdown of the lipoprotein. Cholesterol esterase produced by certain organisms--e.g., Staphylococcus pyogenes and Pseudomonas oeruginosa--augments this fraction both in vitro and in vivo. Endogenous esterase similarly increases the amount of cholesterol-peptide complex, a mechanism which may be activated as a feedback process following binding of toxin to the cholesterol component of the complex. These complexes will thus supply a readily available means of binding bacterial toxins before antibody formation begins; Cholesterol-peptide complexes, either alone or modified by binding to toxin, may function as autoantigens. It is postulated that immune complexes so formed may be involved in atherosclerosis either by directly damaging vessels walls or by cross-reaction of antibody with cell-membrane-bound lipoproteins which equilibrate with plasma-lipoproteins.