In vitro analysis of verapamil-induced immunosuppression: potent inhibition of T cell motility and lymphocytic transmigration through allogeneic endothelial cells

BACKGROUND

Cyclosporine A (CsA) and tacrolimus prevent proliferation but not transendothelial migration of alloreactive lymphocytes into donor organs. As a result, serious adverse effects, such as nephrotoxicity and neurotoxicity, have been observed under CsA/tacrolimus therapy. The incorporation of new drugs with infiltration blocking properties might enhance the efficacy of the current immunosuppressive protocol, allowing lower CsA/tacrolimus dosage. Because Ca2+ plays a critical role in cell-cell interaction, the Ca2+-channel blocker verapamil might be a good cany. didate for supporting CsA/tacrolimus-based therapy.

METHODS

A T-cell endothelial cell coculture model or immobilized immunoglobulin G globulin chimeras were employed to investigate how S- and R- verapamil interfere with the lymphocytic infiltration process. The expression and arrangement of membranous adhesion receptors and cytoskeletal F-actin filaments were analyzed by fluorometric method in the presence of. verapamil.

RESULTS

Both verapamil enantiomers strongly inhibited lymphocyte infiltration. CD4+ and CD8+ T-cells were influenced to a similar extent with regard to horizontal locomotion (CD4+=CD8+), but to a different extent with regard to adhesion and penetration (CD4+ > CD8+). Moreover, penetration was blocked to a higher extent than was adhesion. ID50-values were 31 microM (CD4+-adhesion) and 11 microM (CD4+-penetration). Verapamil reduced P-selectin expression on endothelial cells and effectively down-regulated binding of T-cells to immobilized P-selectin immunoglobulin G globulins (ID50=4.4 microM; CD4+). A verapamil-induced reduction of intracellular F-actin in T-lymphocytes was proven to be mainly responsible for diminished cell locomotion.

CONCLUSIONS

The prevention of CD4+ T-cell penetration by verapamil might argue for its use as an adjunct to CsA/tacrolimus-based immunosuppressive therapy.

Evaluation of efficacy and plasma concentrations of ropivacaine in continuous axillary brachial plexus block: high dose for surgical anesthesia and low dose for postoperative analgesia

BACKGROUND AND OBJECTIVES

Ropivacaine is a potent local anesthetic that, experimentally at low concentrations, produces an effective block of pain conducting nerve fibers. Therefore, it was hypothesized that 0.1% and 0.2% ropivacaine would provide clinically adequate postoperative analgesia in continuous axillary plexus block.

METHODS

Sixty patients (ASA I-II) scheduled for elective hand or forearm surgery received 5 mg/kg of 0.75% ropivacaine for axillary block using nerve stimulator technique. One hour later, in random order, a continuous infusion of either 0.1% ropivacaine (0.125 mg/kg/h), 0.2% ropivacaine (0.25 mg/kg/h) or saline 6 to 11 mL/h was started.

RESULTS

The mean total ropivacaine dose for the surgical block was 5.1 to 5.2 mg/kg with the supplementation. All patients were pain free for the first 12 to 15 hours after the block. The need for postoperative analgesics during the infusion was similar in all groups. After the initial block, the maximum plasma concentrations (mean 2.5 microg/mL) were measured at 45 or 60 minutes after injection. The highest individual plasma concentration was 4.2 microg/mL. Despite the high venous peak concentration, no toxic reactions were observed. The mean peak plasma concentration (Cmax) was 2.2+/-0.5 microg/mL for saline, 2.6+/-0.8 microg/mL for 0.1% ropivacaine, and 2.6+/-0.7 microg/mL for 0.2% ropivacaine. During the continuous infusion of 24 hours, the ropivacaine concentration declined steadily.

CONCLUSIONS

Ropivacaine is safe and effective for axillary brachial plexus block. The continuous infusion of 0.1% or 0.2% ropivacaine was no more beneficial than an infusion of saline in relieving postoperative pain in patients having elective hand surgery. None of the infusions were sufficient to adequately treat the patients' pain without the addition of adjunct agents.

Stimulation with carbachol alters endomembrane distribution and plasma membrane expression of intracellular proteins in lacrimal acinar cells

The events that lead to Sjögren's autoimmune processes in the lacrimal gland remain poorly understood. The acinar cell's responses to acute cholinergic stimulation include release of secretory products across the apical plasma membrane (apm) and a number of processes related to traffic between endomembrane compartments and the basal-lateral plasma membranes (blm), such as recruitment of Na, K-ATPase, accelerated recycling, and accelerated transcytosis of secretory IgA. We tested the hypothesis that stimulation-induced acceleration of endomembrane traffic is accompanied by changes in compartmentation and increased blm expression of proteins that are normally sequestered in endomembrane compartments. Isolated rabbit lacrimal gland acinar cells were cultured in serum-free media for 2 days. After harvesting, cells were incubated with or without 10 microm carbachol at 37 degrees C for 20 min. Cells were lysed, and lysates were analysed by isopycnic centrifugation on sorbitol gradients. Galactosyltransferase catalytic activity was determined biochemically. Different forms of cathepsin B were detected by Western blotting. Carbachol stimulation decreased the contents of beta-hexosaminidase, alpha-glucosidase, and protein in secretory vesicles and increased them in specific compartments of the trans-Golgi network (ld-tgns). Stimulation also caused levels of galactosyltransferase, preprocathepsin B, and procathepsin B to increase two- to three-fold in the blm as well as increasing in the ld-tgns. Other changes caused by sustained stimulation included: (a) increased levels of protein and procathepsin B in compartments of the lysosomal pathway; (b) changes in the distributions of Rab5 within the endomembrane system; (c) changes in the distribution of Rab6 within the Golgi complex and tgn; (d) decreased expression of acid phosphatase and MHC class II molecules in the blm; and (e) decreased total content of Na,K-ATPase, which appeared to have been selectively depleted from the tgn and blmre. We propose that the normal compartmentation of certain proteins may allow them to remain cryptic, such that they are not subject to central tolerance. Stimulation-induced increases in the levels expressed at the blm or secreted to the interstitium may, therefore, contribute to initiation of local autoimmune responses.

Interleukin-4 causes susceptibility to invasive pulmonary aspergillosis through suppression of protective type I responses

Aspergillus fumigatus, an opportunistic fungal pathogen, causes multiple allergic and nonallergic airway diseases. Invasive pulmonary aspergillosis (IPA) is a nonallergic, life-threatening disease of immunocompromised patients. In a murine model of IPA, interleukin (IL)-4-deficient (IL-4-/-) BALB/c mice were used to examine the role of IL-4 in lung pathology and immune responses. IL-4-/- mice were more resistant than wild-type mice to infection caused by multiple intranasal injections of viable A. fumigatus conidia. Resistance was associated with decreased lung inflammatory pathology, impaired T helper (Th)-2 responses (including lung eosinophilia), and an IL-12-dependent Th1 response. In contrast, development of host-detrimental antifungal Th2 cells occurred in IL-12-/- and interferon-gamma-/- mice and in IL-4-/- mice when subjected to IL-12 neutralization. These results demonstrate that IL-4 renders mice susceptible to infection with A. fumigatus by inhibition of protective Th1 responses. IL-4 appears to have a distinct role in the pathogenesis of allergic and nonallergic lung diseases caused by the fungus.

MHC class II molecules, cathepsins, and La/SSB proteins in lacrimal acinar cell endomembranes

Sjögren's syndrome is a chronic autoimmune disease affecting the lacrimal glands and other epithelia. It has been suggested that acinar cells of the lacrimal glands provoke local autoimmune responses, leading to Sjögren's syndrome when they begin expressing major histocompatibility complex (MHC) class II molecules. We used isopycnic centrifugation and phase partitioning to resolve compartments that participate in traffic between the basolateral membranes and the endomembrane system to test the hypothesis that MHC class II molecules enter compartments that contain potential autoantigens, i.e., La/SSB, and enzymes capable of proteolytically processing autoantigen, i.e., cathepsins B and D. A series of compartments identified as secretory vesicle membranes, prelysosomes, and microdomains of the trans-Golgi network involved in traffic to the basolateral membrane, to the secretory vesicles, and to the prelysosomes were all prominent loci of MHC class II molecules, La/SSB, and cathepsins B and D. These observations support the thesis that lacrimal gland acinar cells that have been induced to express MHC class II molecules function as autoantigen processing and presenting cells.

Protein-protein interaction of the Ro-ribonucleoprotein particle using multiple antigenic peptides

Protein protein interactions play a significant role in maintaining the structural and functional integrity of the cell. We used multiple antigen peptides (MAPs) to analyze such interactions within the Ro (or SSA) ribonucleoprotein complex. Our data showed that 60 kD Ro and La colocalize in the nucleus of the cell. Previous data have indicated that 60 kD Ro and La co-exist via interactions with the hYRNAs. We were interested to see whether 60 kD Ro and La interact with each other through protein protein interactions. MAPs were produced with sequences derived from the autoepitopes of 60 kD Ro. When used in agarose immunodiffusion certain MAPs formed precipitin lines specifically with Ro and La antigens. Used in affinity chromatography the Ro MAPs purified the Ro ribonucleoprotein particle from lymphocyte extract. Solid phase immunoassay and surface plasmon resonance (SPR) confirmed the observations obtained with agarose diffusion. Using SPR, kinetic analyses gave an apparent affinity constant of about 1 x 10(7) M(-1) for Ro-MAP-60 kD Ro interactions. The autoantigens Ro and La are specific targets in autoimmune diseases, particularly systemic lupus erythematosus (SLE) and Sjögren's syndrome, and are known to exist together as a complex with hYRNAs. The present data indicate that there are protein-protein interactions between Ro and La.

Generating functionals for harmonic expectation values of paths with fixed end points: Feynman diagrams for nonpolynomial interactions

We introduce a general class of generating functionals for the calculation of quantum-mechanical expectation values of arbitrary functionals of fluctuating paths with fixed end points in configuration or momentum space. The generating functionals are calculated explicitly for the harmonic oscillator with time-dependent frequency, and used to derive a smearing formula for correlation functions of polynomial and nonpolynomial functions of time-dependent positions and momenta. This formula summarizes the effect of quantum fluctuations, and serves to derive generalized Wick rules and Feynman diagrams for perturbation expansions of nonpolynomial interactions.

Androgen influence on lacrimal gland apoptosis, necrosis, and lymphocytic infiltration

PURPOSE

Previous studies have shown that ovariectomy and hypophysectomy cause regression of the lacrimal gland and have implicated androgens as trophic hormones that support the gland. The purposes of this study were to test the hypothesis that glandular regression after ovariectomy is due to apoptosis, to identify the cell type or types that undergo apoptosis, to survey the time course of the apoptosis, and to determine whether ovariectomy-induced apoptosis could be prevented by dihydrotestosterone (DHT) treatment.

METHODS

Groups of sexually mature female New Zealand White rabbits were ovariectomized and killed at various time periods up to 9 days. Additional groups of ovariectomized rabbits were treated with 4 mg/kg DHT per day. At each time period, sham-operated rabbits were used as controls. Lacrimal glands were removed and processed for analysis of apoptosis as assessed by DNA fragmentation and for morphologic examination. DNA fragmentation was determined using the TdT-dUTP terminal nick-end labeling assay and by agarose gel electrophoresis. Labeled nuclei were quantified by automated densitometry. Sections were also stained for RTLA (rabbit thymic lymphocyte antigen), rabbit CD18, and La antigen. Morphology was evaluated by both light and electron microscopy.

RESULTS

The time course of apoptosis exhibited two phases, a rapid and transient phase and a second prolonged phase. A transient phase peaked at approximately 4 to 6 hours after ovariectomy. The values for degraded DNA as a percentage of total nuclear area were 4.29%+/-0.79% and 4.26%+/-0.54%, respectively. The values for sham-operated controls examined at the same time periods were 1.77%+/-0.08% and 0.82%+/-0.21%, respectively. The percentage of degraded DNA at 24 hours after ovariectomy was not different from controls examined at the same interval after sham operation. The percentage of degraded DNA 6 days after ovariectomy was significantly increased (8.5%+/-2.4%), compared with sham-operated animals at the same time period (0.68%+/-0.03%). DNA laddering was more pronounced after ovariectomy. Dihydrotestosterone treatment in ovariectomized rabbits suppressed the increase in DNA degradation. Morphologic examination of lacrimal gland sections indicated that ovariectomy caused apoptosis of interstitial cells rather than acinar or ductal epithelial cells. Tissue taken 4 hours and 6 days after ovariectomy showed nuclear chromatin condensation principally in plasma cells. Increased numbers of macrophages were also evident. Significant levels of cell degeneration and cell debris, characteristic of necrosis, were observed in acinar regions 6 days after ovariectomy. Dihydrotestosterone prevented this necrosis. Increased numbers of RTLA+, CD18+, and La+ interstitial cells were also evident 6 days after ovariectomy. In addition, ovariectomy increased La expression in ductal cells. Dihydrotestosterone treatment prevented the increase in numbers of lymphoid cells and La expression. Dihydrotestosterone also promoted the appearance of mitotic figures in acinar cells and increased the sizes of acini by 43% (P < 0.05).

CONCLUSIONS

Glandular atrophy observed after ovariectomy is likely to proceed by necrosis of acinar cells rather than apoptosis. This process begins with an apparent time lag after a rapid phase of interstitial cell apoptosis. These processes are accompanied by increased lymphocytic infiltration. These results suggest that a critical level of androgen is necessary to maintain lacrimal gland structure and function and that a decrease in available androgen below this level could trigger lacrimal gland apoptosis and necrosis, and an autoimmune response. Because apoptotic and necrotic cell fragments may be sources of autoantigens that can be processed and presented to initiate an autoimmune reaction, we surmise that cell death triggered by androgen withdrawal may trigger an autoimmune response such as that encountered in Sjögren's syndrome. (ABSTRACT TRUNCATED)

Overexpression and functional characterization of kinin receptors reveal subtype-specific phosphorylation

G protein-coupled receptors such as the receptors for bradykinin are present in low copy numbers in most natural cells. To overcome the problems associated with the analysis of these receptors at the protein level, we used highly efficient expression systems such as the baculovirus/insect cell system. However, the structural and functional statuses of recombinant receptors have often remained elusive. We have expressed the two types of human kinin receptors, B1 and B2, in Sf9 cells. Both receptors are found on the surface of infected cells where they display the same pharmacological profiles as their cognate receptors of native cells. The functional analysis of kinin receptors coupled to the intracellular signaling pathways of Sf9 cells revealed differential patterns of ligand-induced phosphorylation for the two kinin receptors. The B1 receptor failed to undergo ligand-induced phosphorylation. However the B2 receptor showed selective phosphorylation of a minor 38 kDa band and lack of phosphorylation of a dominant 33 kDa band, indicating that only a fraction of the receptor protein is functionally linked to the kinase pathway. A striking discrepancy between the number of binding sites and the amount of receptor protein per cell (molar ratio of 1:20 to 1:1000) indicated that a significant portion of kinin receptors is associated with the intracellular compartments of Sf9 cells. Pulse-chase and immunoprecipitation experiments demonstrated that the heterogeneity of recombinant receptors is not due to proteolytic processing but likely reflects incomplete or lacking N-glycosylation. We conclude that the baculovirus/Sf9 system is suitable for the recombinant expression and functional analysis of kinin receptors though limitations of the system have to be considered.

Analysis of epitope spreading over an eleven-year period in a patient with systemic lupus erythematosus

During a period of more than eleven years serum samples of a patient with Systemic Lupus Erythematosus were collected and analyzed for anti-nuclear autoantibodies. High titer of anti-La/SS-B were detectable in all serum samples. The La/SS-B epitopes remained constant. Besides anti-La/SS-B antibodies all serum samples contained traces of anti-Ro/SS-A including anti-Ro52 and anti-Ro60 antibodies. During disease flares anti-Ro/SS A antibodies were upregulated and anti-dsDNA antibodies appeared, thus supporting the concept of an antigen driven intermolecular epitope spreading to Ro/SS-A and dsDNA.

Identification of human autoantigen La/SS-B as BC1/BC200 RNA-binding protein

Rodent BC1 RNA and primate BC200 RNA are small cytoplasmic non-messenger RNAs that are phylogenetically unrelated. Nevertheless, the two RNAs exhibit a large degree of parallelism. In addition to some sequence similarities in their 3' domains, they are prevalently expressed in a similar subset of neurons and belong to a small group of transcripts with a somatodendritic location. Both RNAs are complexed with proteins as ribonucleoprotein particles (RNPs). Their similarities may even extend to analogous functional roles, for example, in the regulation of decentralized dendritic translation. To shed further light on the physiological role(s) of the BC1/BC200 RNPs, we began to analyze protein components that specifically bind to these RNAs. Ultraviolet-crosslinking experiments and affinity purification techniques revealed that the human autoantigen La/SS-B is associated with BC1/BC200 RNA in vitro and in vivo. As with other RNA polymerase III transcripts, La protein binds with high affinity to the 3' end of BC200 RNA. Our results suggest that an additional function of La may be control of dendritic translation by providing a link between the 5' Alu domain of BC200 RNP and the ribosome via the La protein dimer. The fact that La binds both BC1 and BC200 RNAs further supports the notion that the RNAs are functional analogs despite the fact that they arose from two separate retroposition events in two different mammalian lineages.

Increased mature interleukin-1beta (IL-1beta) secretion from THP-1 cells induced by nigericin is a result of activation of p45 IL-1beta-converting enzyme processing

Perregaux and Gabel (Perregaux, D., and Gabel, C. A. (1994) J. Biol. Chem. 269, 15195-15203) reported that potassium depletion of lipopolysaccharide-stimulated mouse macrophages induced by the potassium ionophore, nigericin, leads to the rapid release of mature interleukin-1beta (IL-1beta). We have now shown a similar phenomenon in lipopolysaccharide-stimulated human monocytic leukemia THP-1 cells. Rapid secretion of mature, 17-kDa IL-1beta occurred, in the presence of nigericin (4-16 microM). No effects on the release of tumor necrosis factor-alpha, IL-6, or proIL-1beta were seen. Addition of the irreversible interleukin-1beta-converting enzyme (ICE) inhibitor, Z-Val-Ala-Asp-dichlorobenzoate, or a radicicol analog, inhibited nigericin-induced mature IL-1beta release and activation of p45 ICE precursor. The radicicol analog itself did not inhibit ICE, but markedly, and very rapidly depleted intracellular levels of 31-kDa proIL-1beta. By contrast, dexamethasone, cycloheximide, and the Na+/H+ antiporter inhibitor, 5-(N-ethyl-N-isopropyl)amiloride, had no effect on nigericin-induced release of IL-1beta. We have therefore shown conclusively, for the first time, that nigericin-induced release of IL-1beta is dependent upon activation of p45 ICE processing. So far, the mechanism by which reduced intracellular potassium ion concentration triggers p45 ICE processing is not known, but further investigation in this area could lead to the discovery of novel molecular targets whereby control of IL-1beta production might be effected.

The human autoantigen La/SS-B accelerates herpes simplex virus type 1 replication in transfected mouse 3T3 cells

Permanently transfected mouse cell lines which expressed different levels of the human autoantigen La/SS-B were infected with different strains of herpes simplex virus type 1, including the strains ANG, HSZP, 17syn+ and HFEM. During infection the localization of the human La protein was followed using an anti-La MoAb, which recognized only the human La protein but did not cross-react with either the endogenous mouse La protein or any viral encoded protein. After infection La protein was transported from the nucleus to the cytoplasm. The time course of translocation was dependent on the amount of human La protein expressed in the respective cell line. Moreover, acceleration of viral replication was dependent on the level of expression of human La protein, suggesting that La protein is a cellular factor that facilitates virus replication.

The multiligand-binding protein gC1qR, putative C1q receptor, is a mitochondrial protein

A protein of 33 kDa (p33) that tightly binds to the globular domains of the first complement component, C1q, is thought to serve as the major C1q receptor (gC1qR) on B cells, neutrophils, and mast cells. However, the cellular routing and the subcellular localization of p33/gC1qR are unknown. We have performed confocal laser-scanning microscopy and found that p33/gC1qR is present in intracellular compartments, where it colocalizes with the mitochondrial marker protein, pyruvate dehydrogenase. No surface staining for p33/gC1qR on endothelial EA.hy926 cells was observed. A fusion protein of the p33/gC1qR presequence with green fluorescent protein translocated to the mitochondria of transfected COS-7 cells. Concomitantly, a 6-kDa portion of the fusion protein was proteolytically removed. The 33 amino-terminal residues of the presequence proved sufficient to direct reporter constructs to mitochondria. Association of p33/gC1qR with mitoplasts indicated that the mature protein of 209 residues resides in the matrix and/or the inner membrane of mitochondria. Immunocytochemistry of fetal mice tissues revealed a ubiquitous expression of p33/gC1qR, most prominently in tissues that are rich in mitochondria. Thus, the candidate complement receptor p33/gC1qR of intact cells cannot interact with plasma C1q due to mutually exclusive localizations of the components. The functional role of p33/gC1qR needs to be reconsidered.

The value of synthetic linear epitope analogues of La/SSB for the detection of autoantibodies to La/SSB; specificity, sensitivity and comparison of methods

In a previous study it was shown that La/SSB contains four linear epitopes, p147-154, p291-302, p301-318 and p349-364. The aim of the present study was to investigate the value of the synthetic epitope analogues of the La/SSB autoantigen for the detection of antibodies to La/SSB, in comparison with recombinant La and fragments of this protein. A total of 122 sera with anti-La/SSB activity, from patients with primary Sjögren's syndrome (pSS) or systemic lupus erythematosus (SLE), were tested in various peptide-based assays. In addition, 62 sera from pSS or SLE patients with other autoantibody specificities and 95 sera from healthy individuals were used as controls. The autoantibody specificity was identified by counter immunoelectrophoresis and immunoblot. The peptide-based ELISA assays presented sensitivities ranging from 78% to 88-8% and specificities from 69% to 94-3%. Dot blot assays exhibited sensitivities ranging from 93-6% to 97%, but remarkably lower specificities from 56% to 88%. The most sensitive and specific peptide 349GSGKGKVQFQGKKTKF364 was synthesized and attached on a tetramer sequential oligopeptide carrier SOC4 and used for immunoassay development. Assays based on the recombinant native La protein, the La-C terminal (215 aa), and the N-terminal of La with a mutation at base pair 640 (nine adenines instead of eight) were also developed and compared with the SOC4 peptide-based assay. Of anti-La-positive sera, 88.1% were reactive with both the synthetic peptide SOC4-(349-364aa) and the recombinant La protein. Eighty-three percent of sera were reactive with the La N-terminus and 67.8% of sera were reactive with the La C-terminus. Using sera that were anti-Ro-positive but anti-La-negative, 37% were reactive with the recombinant protein, 26% with the La N-terminus, 33% with the La C-terminus and only 11 % with the synthetic peptide. Our results suggest that the synthetic peptide epitopes exhibit high sensitivity and specificity for the detection of anti-La/ SSB antibodies in ELISA and dot blot techniques. The peptide SOC4-(349-364aa) has the same sensitivity for the detection of anti-La/SSB antibodies as the recombinant protein.

Cross-reactivity of antibodies immunoadsorbed to laminin with recombinant human La (SS-B) protein

Anti-La (SS-B) antibodies cross-reacting with mouse B1 laminin were reported in sera of patients with systemic lupus erythematosus. However, the common epitope had not been characterized. Immunoblotting conditions were established, allowing detection and elution of anti-La (SS-B)/laminin cross-reacting antibodies. Antibodies adsorbed to mouse B1 laminin represented a subclass of anti-La antibodies. They strongly reacted with human full length recombinant La protein. However, they failed to react with either an N-terminal La peptide consisting of amino acids 1-192 or a C-terminal La peptide starting at methionine 223, while they still reacted with recombinant La peptides consisting of the amino acids 1-341 or starting at 192. These data indicate that the La (SS-B)/laminin epitope is located between amino acids 192-223 of human La protein, which includes the amino acids EAKLRA, common to the nuclear autoantigen La (SS-B) and the human or mouse B1 laminin.

Analysis of expression of the gene encoding for the nuclear autoantigen La/SS-B using reporter gene constructs

In earlier studies mRNA isoforms encoding for the nuclear autoantigen La were identified. In an alternative La mRNA form the exon 1 was replaced with the exon 1'. Moreover, exon 1' La mRNAs were found to start at different 5'-regions. In dependence on the 5'-start the exon 1' La mRNAs encoded for up to three open reading frames upstream of the La frame, which starts in the exon 2. The exon 1' was located in the intron about 70 nts downstream of the exon 1. The exon 1' La mRNA was proposed to be the result of a promoter switch in combination with an alternative splicing mechanism. The commonly used technique to study the expression of a eucaryotic gene is to fuse a reportergene immediately downstream of the proposed regulatory elements. Due to (i) the short distance between exon 1 and exon 1', (ii) the varying 5'-starts of the exon 1' La mRNAs, and (iii) the upstream open reading frames in the exon 1' La mRNAs this technique appeared to be difficult to apply to the La gene. In order to overcome these problems a luciferase reportergene construct was cloned which started about 2500 nts upstream of the exon 1 and contained the exon 1, the intron including the exon 1', and a portion of the exon 2. Luciferase was fused into the exon 2. This construct was used to prepare 5'-deletion mutants. The constructs were transiently transfected into HeLa cells. RNAs were isolated from the transiently transfected cells and analyzed using the 5'-Rapid Amplification of cDNA End technique. The PCR products were subcloned and sequenced. This analysis showed that exon 1 and exon 1' transcripts were correctly transcribed and spliced from the La luciferase fusion construct. Moreover, the 5'-start of the respective transcript allowed to identify those genomic regions in the La gene that were most likely being involved in determining the respective transcription initiation site. In parallel to the estimation of the 5'-start of the transcripts, the luciferase activity was measured. Thereby we detected a cryptic promoter element in the intron between the exon 1 and exon 2.

The transcription factor NF-ATc1 regulates lymphocyte proliferation and Th2 cytokine production

NF-ATc1 is a member of a family of genes that encodes the cytoplasmic component of the nuclear factor of activated T cells (NF-AT). In activated T cells, nuclear NF-AT binds to the promoter regions of multiple cytokine genes and induces their transcription. The role of NF-ATc1 was investigated in recombination activating gene-1 (RAG-1)-deficient blastocyst complementation assays using homozygous NF-ATc1-/- mutant ES cell lines. NF-ATc1-/-/RAG-1-/- chimeric mice showed reduced numbers of thymocytes and impaired proliferation of peripheral lymphocytes, but normal production of IL-2. Induction in vitro of Th2 responses, as demonstrated by a decrease in IL-4 and IL-6 production, was impaired in mutant T cells. These data indicate that NF-ATc1 plays roles in the development of T lymphocytes and in the differentiation of the Th2 response.

Antibodies protect mice against challenge with tick-borne encephalitis virus (TBEV)-infected macrophages

TBEV is a flavivirus highly pathogenic for humans. By transfer of antibodies directed to the TBEV surface glycoprotein E into mice, immune protection against subsequent inoculation with free TBEV particles could be achieved. After natural TBEV infection via the skin, however, cells of the monocyte/macrophage lineage were recently demonstrated to represent an important source of local virus replication before viraemia occurs. Whether antibodies can protect against virus challenge when contracted in the form of infected cells, however, is still unclear. In the current study, TBEV antibodies protected mice against challenge with either free virus or TBEV-infected macrophages equally well. This observation may be of more general significance.

Increase of sensitivity and validity of the SOS/umu-test after replacement of the beta-galactosidase reporter gene with luciferase

The SOS/umu-test with Salmonella typhimurium TA1535/pSK1002 as tester strain is a rapid and valuable bacterial assay for screening of umuC-dependent mutagenic potential of chemical compounds and chemicals relevant to environmental pollution. The initial assay was modified by replacing the beta-galactosidase reporter gene with luciferase. Thereby, the sensitivity of the umu-test was increased significantly and the susceptibility to intensively coloured solutions was reduced. The alternative enzyme assay in the modified umu-test (umu-Luc) represents an independent method which allows to confirm the colorimetric results obtained with the original SOS/umu-test system (umu-Gal) by measuring the beta-galactosidase activity. It has been proved that for several genotoxins an increased induction rate could be achieved by applying the new umu-Luc test.

De novo acquisition of neuronal polarity in retinoic acid-induced embryonal carcinoma cells

The mouse embryonal carcinoma cell line PCC7-Mz1 represents an advantageous model to study acquisition of polarity by neurons. During the first two days after differentiation is induced by the addition of retinoic acid, the neuronal derivatives develop extensions which for at least four more days do not differ from each other in growth characteristics, morphology, and marker expression. Beginning around differentiation day 6 and following the relocation of the nucleus from a central to a polar position in the cell soma, the morphology and marker expression changes dramatically: expression of MAP2 diminishes and eventually disappears in the thinner neurite (future axon), which originates at the nucleated pole, but remains strong in the branched, broad based neurite(s). The opposite changes in expression are observed for synaptophysin, together with a clustering of the vesicle protein in varicosity-like areas. Complete segregation of expression of the two markers is achieved around day 12, shortly followed by dendrite-specific location of MAP2 mRNA and the ability to generate and conduct action potentials. Our studies add several aspects to the process of neuronal polarity acquisition, as it was previously studied in primary cultures of embryonic neurons: (i) we monitored neuronal differentiation from the birth of neurons, rather than from later and less defined maturation stages, (ii) cell nucleus relocation may be associated with the induction of neuronal polarity, and (iii) functional competence of neurons is closely associated with previous acquisition of polarity. Acquisition of polarity by PCC7-Mz1 neuronal derivatives probably refers to de novo acquisition rather than to reestablishment of polarity.

Dopamine receptor gene expression in an animal model of 'behavioral dependence' on ethanol

The steady-state levels of messenger RNA (mRNA) of five cloned dopamine (D) receptors were measured in five brain regions in rats in a recently developed animal model of 'behavioral dependence' on ethanol. One group of rats was given the choice between ethanol and water over a 9-month period and developed 'behavioral dependence' on ethanol (group a). This group was compared with a group given the choice between ethanol and water for only 2 months (not yet behaviorally dependent, group b), a group forced to consume ethanol as sole fluid over a 9-month period (not behaviorally dependent, group c) and ethanol-naive control rats. All groups were sacrificed 1 month after ethanol withdrawal. The concentrations of mRNA of D3-receptors in the limbic forebrain (which included the nucleus accumbens) were significantly lowered in groups a and b, but unchanged in group c. D3 mRNA levels were reduced in the hippocampus of group b and unchanged in the cortex, amygdala and striatum. No significant changes in the mRNA concentrations of D1-, D2-, D4- or D5-receptors were seen in the five brain regions in any group. In conclusion, chronic consumption of ethanol under the 'free-choice condition', which may best induce the drug-rewarding effect, leads to specific changes in the D3-receptor gene expression which were not seen after forced ethanol administration. Changes in D3 mRNA levels were, however, not a specific correlate of 'behavioral dependence', as they were also detected in rats not yet 'behaviorally dependent' (group b).

Characterization of murine monoclonal antibodies against the Ro52 autoantigen

Immunization of BALB/c mice with purified recombinant human Ro52 protein resulted in three anti-Ro52 MoAbs termed 2E7, 4C6 and 4F11. All anti-Ro52 MoAbs specifically reacted with recombinant human Ro52 protein, and also with Ro52 protein in total extracts of all human cell lines analysed, including the epithelial cell line HeLa, the B cell line Raji, the bladder carcinoma cell line RT112, and a fibroblast cell line derived from patients with xeroderma pigmentosum. The anti-Ro52 MoAbs were able to immunoprecipitate the recombinant human Ro52 protein expressed in wheat germ extract, but failed to precipitate hY RNAs from cell extracts. The staining pattern of the MoAbs strongly differed between the RT112 cells and the fibroblast cell line. RT112 cells displayed an intense cytoplasmic staining and in addition distinct fine nuclear speckles. In contrast, in the fibroblast cell line no cytoplasmic staining but only staining of distinct nuclear speckles was observed. Using deletion mutants of Ro52 the epitopes recognized by the anti-Ro52 MoAbs 2E7, 4C6 and 4F11 were partially mapped. All three MoAbs appeared to recognize distinct epitopes, that are located in the regions of Ro52 bordered by amino acids 136-164, 208-363 and 136-190, respectively. These MoAbs can be of great use in studying the cellular processes in which the Ro52 protein is involved.

Impaired CD28-mediated interleukin 2 production and proliferation in stress kinase SAPK/ERK1 kinase (SEK1)/mitogen-activated protein kinase kinase 4 (MKK4)-deficient T lymphocytes

The dual specific kinase SAPK/ERK1 kinase (SEK1; mitogen-activated protein kinase kinase 4/Jun NH2 terminal kinase [ JNK] kinase) is a direct activator of stress-activated protein kinases ([SAPKs]/JNKs) in response to CD28 costimulation, CD40 signaling, or activation of the germinal center kinase. Here we show that SEK1(-/-) recombination-activating gene (RAG)2(-/-) chimeric mice have a partial block in B cell maturation. However, peripheral B cells displayed normal responses to IL-4, IgM, and CD40 cross-linking. SEK1(-/-) peripheral T cells showed decreased proliferation and IL-2 production after CD28 costimulation and PMA/Ca2+ ionophore activation. Although CD28 expression was absolutely crucial to generate vesicular stomatitis virus (VSV)-specific germinal centers, SEK1(-/-)RAG2(-/-) chimeras mounted a protective antiviral B cell response, exhibited normal IgG class switching, and made germinal centers in response to VSV. Interestingly, PMA/Ca2+ ionophore stimulation, which mimics TCR-CD3 and CD28-mediated signal transduction, induced SAPK/JNK activation in peripheral T cells, but not in thymocytes, from SEK1(-/-) mice. These results show that signaling pathways for SAPK activation are developmentally regulated in T cells. Although SEK1(-/-) thymocytes failed to induce SAPK/JNK in response to PMA/Ca2+ ionophore, SEK1(-/-)RAG2(-/-) thymocytes proliferated and made IL-2 after PMA/Ca2+ ionophore and CD3/CD28 stimulation, albeit at significantly lower levels compared to SEK1(+/+)RAG2(-/-) thymocytes, implying that CD28 costimulation and PMA/Ca2+ ionophore-triggered signaling pathways exist that can mediate proliferation and IL-2 production independently of SAPK activation. Our data provide the first genetic evidence that SEK1 is an important effector molecule that relays CD28 signaling to IL-2 production and T cell proliferation.