Membrane Targeted Azobenzene Drives Optical Modulation of Bacterial Membrane Potential

Recent studies have shown that bacterial membrane potential is dynamic and plays signaling roles. Yet, little is still known about the mechanisms of membrane potential dynamics regulation-owing to a scarcity of appropriate research tools. Optical modulation of bacterial membrane potential could fill this gap and provide a new approach for studying and controlling bacterial physiology and electrical signaling. Here, the authors show that a membrane-targeted azobenzene (Ziapin2) can be used to photo-modulate the membrane potential in cells of the Gram-positive bacterium Bacillus subtilis. It is found that upon exposure to blue-green light (λ = 470 nm), isomerization of Ziapin2 in the bacteria membrane induces hyperpolarization of the potential. To investigate the origin of this phenomenon, ion-channel-deletion strains and ion channel blockers are examined. The authors found that in presence of the chloride channel blocker idanyloxyacetic acid-94 (IAA-94) or in absence of KtrAB potassium transporter, the hyperpolarization response is attenuated. These results reveal that the Ziapin2 isomerization can induce ion channel opening in the bacterial membrane and suggest that Ziapin2 can be used for studying and controlling bacterial electrical signaling. This new optical tool could contribute to better understand various microbial phenomena, such as biofilm electric signaling and antimicrobial resistance.

Integration of bio-responsive silver in 1D photonic crystals: towards the colorimetric detection of bacteria

The colour purity and versatility of fabrication of one-dimensional photonic crystals (1D PhCs) make them ideal candidates for colorimetric sensing of a variety of analytes. For instance, the detection of bacterial contaminants in food via colorimetric sensors can be highly appealing, as most of the existing detection techniques are in general time-consuming and the read-out requires specialised personnel. Here, we present a colorimetric sensor based on hybrid plasmonic/photonic 1D crystals. We demonstrate that the modification of the silver plasmon resonance brought about by the effective silver/bacterium interaction can be translated into the visible spectral region, producing a change in the structural colour. In addition, we observe a superior colorimetric sensitivity against the Gram negative Escherichia coli compared to the Gram positive Micrococcus luteus, a result that we attribute to the more efficient electrostatic interaction and cellular adhesion between the silver surface and the Gram-negative bacteria outer membrane. This approach demonstrates that in principle an easy colorimetric detection of bacterial contaminants can be achieved through the use of bio-responsive plasmonic materials, such as silver, whose selective electrostatic interaction with bacterial cell wall is well-known and occurs without the need of chemical functionalisation.

Rational backbone redesign of a fructosyl peptide oxidase to widen its active site access tunnel

Fructosyl peptide oxidases (FPOXs) are enzymes currently used in enzymatic assays to measure the concentration of glycated hemoglobin and albumin in blood samples, which serve as biomarkers of diabetes. However, since FPOX are unable to work directly on glycated proteins, current enzymatic assays are based on a preliminary proteolytic digestion of the target proteins. Herein, to improve the speed and costs of the enzymatic assays for diabetes testing, we applied a rational design approach to engineer a novel enzyme with a wider access tunnel to the catalytic site, using a combination of Rosetta design and molecular dynamics simulations. Our final design, L3_35A, shows a significantly wider and shorter access tunnel, resulting from the deletion of five-amino acids lining the gate structures and from a total of 35 point mutations relative to the wild-type (WT) enzyme. Indeed, upon experimental testing, our engineered enzyme shows good structural stability and maintains significant activity relative to the WT.

Structural characterization of human O-phosphoethanolamine phospho-lyase

Human O-phosphoethanolamine phospho-lyase (hEtnppl; EC 4.2.3.2) is a pyridoxal 5'-phosphate-dependent enzyme that catalyzes the degradation of O-phosphoethanolamine (PEA) into acetaldehyde, phosphate and ammonia. Physiologically, the enzyme is involved in phospholipid metabolism, as PEA is the precursor of phosphatidylethanolamine in the CDP-ethanolamine (Kennedy) pathway. Here, the crystal structure of hEtnppl in complex with pyridoxamine 5'-phosphate was determined at 2.05 Å resolution by molecular replacement using the structure of A1RDF1 from Arthrobacter aurescens TC1 (PDB entry 5g4i) as the search model. Structural analysis reveals that the two proteins share the same general fold and a similar arrangement of active-site residues. These results provide novel and useful information for the complete characterization of the human enzyme.

Insight into GEBR-32a: Chiral Resolution, Absolute Configuration and Enantiopreference in PDE4D Inhibition

Alzheimer's disease is the most common type of dementia, affecting millions of people worldwide. One of its main consequences is memory loss, which is related to downstream effectors of cyclic adenosine monophosphate (cAMP). A well-established strategy to avoid cAMP degradation is the inhibition of phosphodiesterase (PDE). In recent years, GEBR-32a has been shown to possess selective inhibitory properties against PDE type 4 family members, resulting in an improvement in spatial memory processes without the typical side effects that are usually correlated with this mechanism of action. In this work, we performed the HPLC chiral resolution and absolute configuration assignment of GEBR-32a. We developed an efficient analytical and semipreparative chromatographic method exploiting an amylose-based stationary phase, we studied the chiroptical properties of both enantiomers and we assigned their absolute configuration by 1H-NMR (nuclear magnetic resonance). Lastly, we measured the IC50 values of both enantiomers against both the PDE4D catalytic domain and the long PDE4D3 isoform. Results strongly support the notion that GEBR-32a inhibits the PDE4D enzyme by interacting with both the catalytic pocket and the regulatory domains.

Micro- and Nanopatterned Silk Substrates for Antifouling Applications

A major problem of current biomedical implants is the bacterial colonization and subsequent biofilm formation, which seriously affects their functioning and can lead to serious post-surgical complications. Intensive efforts have been directed toward the development of novel technologies that can prevent bacterial colonization while requiring minimal antibiotics doses. To this end, biocompatible materials with intrinsic antifouling capabilities are in high demand. Silk fibroin, widely employed in biotechnology, represents an interesting candidate. Here, we employ a soft-lithography approach to realize micro- and nanostructured silk fibroin substrates, with different geometries. We show that patterned silk film substrates support mammal cells (HEK-293) adhesion and proliferation, and at the same time, they intrinsically display remarkable antifouling properties. We employ Escherichia coli as representative Gram-negative bacteria, and we observe an up to 66% decrease in the number of bacteria that adhere to patterned silk surfaces as compared to control, flat silk samples. The mechanism leading to the inhibition of biofilm formation critically depends on the microstructure geometry, involving both a steric and a hydrophobic effect. We also couple silk fibroin patterned films to a biocompatible, optically responsive organic semiconductor, and we verify that the antifouling properties are very well preserved. The technology described here is of interest for the next generation of biomedical implants, involving the use of materials with enhanced antibacterial capability, easy processability, high biocompatibility, and prompt availability for coupling with photoimaging and photodetection techniques.

Hybrid plasmonic/photonic crystals for optical detection of bacterial contaminants

Here, we show that a hybrid plasmonic/photonic crystal consisting of a thin layer of bioactive plasmonic material (i.e. silver) deposited on top a 1D PhC can detect one of the most common bacterial contaminant, namely Escherichia coli. We speculate that the change in the plasmon charge density brought about by metal/bacterium interaction results in a variation of the plasmon resonance that, in turns, translates in a shift of the photonic structural color.

Hybrid One-Dimensional Plasmonic-Photonic Crystals for Optical Detection of Bacterial Contaminants

Photonic crystal-based biosensors hold great promise as low-cost devices for real-time monitoring of a variety of biotargets, for example, bacterial contaminants in food. Here, we report the proof-of-concept for a new colorimetric sensor of bacterial contamination, which is based on a novel hybrid plasmonic-photonic device. Our system consists of a layer of silver, a plasmonic metal exhibiting a well-known bioactivity, on top of a one-dimensional photonic crystal. We attribute the bioresponsivity to the formation of polarization charges at the Ag/bacterium interface within a sort of "bio-doping" mechanism. Interestingly, this triggers a blue shift in the photonic response. As an example, we assessed the validity of our approach by detecting one of the most hazardous contaminants, Escherichia coli. This work demonstrates that our device can be a low-cost and portable platform for the detection of common bacterial contaminants.

Biohybrid Electrospun Membrane for the Filtration of Ketoprofen Drug from Water

A current challenge in materials science and biotechnology is to express a specific and controlled functionality on the large interfacial area of a nanostructured material to create smart biohybrid systems for targeted applications. Here, we report on a biohybrid system featuring poly(vinyl alcohol) as the supporting synthetic polymer and bovine serum albumin as the biofunctional element. The optimal processing conditions to produce these self-standing composite membranes are determined, and the composition and distribution of the bioactive agent within the polymeric matrices are analyzed. A post-processing cross-linking using glutaraldehyde enables this functional membrane to be used as a chemical filter in aqueous environments. By demonstrating that our mats can remove large amounts of ketoprofen from water, we show that the combination of a BSA-induced biofunctionality with a nanostructured fibrous material allows for the development of an efficient biohybrid filtering device for the large and widely used family of nonsteroidal anti-inflammatory drugs (NSAIDs). The crystal structure of the complex between BSA and ketoprofen is determined for the first time and confirms the interaction between the two species.

Structure-Based Virtual Screening Allows the Identification of Efficient Modulators of E-Cadherin-Mediated Cell-Cell Adhesion

Cadherins are a large family of transmembrane calcium-dependent cell adhesion proteins that orchestrate adherens junction formation and are crucially involved in tissue morphogenesis. Due to their important role in cancer development and metastasis, cadherins can be considered attractive targets for drug discovery. A recent crystal structure of the complex of a cadherin extracellular portion and a small molecule inhibitor allowed the identification of a druggable interface, thus providing a viable strategy for the design of cadherin dimerization modulators. Here, we report on a structure-based virtual screening approach that led to the identification of efficient and selective modulators of E-cadherin-mediated cell–cell adhesion. Of all the putative inhibitors that were identified and experimentally tested by cell adhesion assays using human pancreatic tumor BxPC-3 cells expressing both E-cadherin and P-cadherin, two compounds turned out to be effective in inhibiting stable cell–cell adhesion at micromolar concentrations. Moreover, at the same concentrations, one of them also showed anti-invasive properties in cell invasion assays. These results will allow further development of novel and selective cadherin-mediated cell–cell adhesion modulators for the treatment of a variety of cadherin-expressing solid tumors and for improving the efficiency of drug delivery across biological barriers.

Molecular Bases of PDE4D Inhibition by Memory-Enhancing GEBR Library Compounds

Selected members of the large rolipram-related GEBR family of type 4 phosphodiesterase (PDE4) inhibitors have been shown to facilitate long-term potentiation and to improve memory functions without causing emetic-like behavior in rodents. Despite their micromolar-range binding affinities and their promising pharmacological and toxicological profiles, few if any structure-activity relationship studies have been performed to elucidate the molecular bases of their action. Here, we report the crystal structure of a number of GEBR library compounds in complex with the catalytic domain of PDE4D as well as their inhibitory profiles for both the long PDE4D3 isoform and the catalytic domain alone. Furthermore, we assessed the stability of the observed ligand conformations in the context of the intact enzyme using molecular dynamics simulations. The longer and more flexible ligands appear to be capable of forming contacts with the regulatory portion of the enzyme, thus possibly allowing some degree of selectivity between the different PDE4 isoforms.

Review: Engineering of thermostable enzymes for industrial applications

The catalytic properties of some selected enzymes have long been exploited to carry out efficient and cost-effective bioconversions in a multitude of research and industrial sectors, such as food, health, cosmetics, agriculture, chemistry, energy, and others. Nonetheless, for several applications, naturally occurring enzymes are not considered to be viable options owing to their limited stability in the required working conditions. Over the years, the quest for novel enzymes with actual potential for biotechnological applications has involved various complementary approaches such as mining enzyme variants from organisms living in extreme conditions (extremophiles), mimicking evolution in the laboratory to develop more stable enzyme variants, and more recently, using rational, computer-assisted enzyme engineering strategies. In this review, we provide an overview of the most relevant enzymes that are used for industrial applications and we discuss the strategies that are adopted to enhance enzyme stability and/or activity, along with some of the most relevant achievements. In all living species, many different enzymes catalyze fundamental chemical reactions with high substrate specificity and rate enhancements. Besides specificity, enzymes also possess many other favorable properties, such as, for instance, cost-effectiveness, good stability under mild pH and temperature conditions, generally low toxicity levels, and ease of termination of activity. As efficient natural biocatalysts, enzymes provide great opportunities to carry out important chemical reactions in several research and industrial settings, ranging from food to pharmaceutical, cosmetic, agricultural, and other crucial economic sectors.

Biochemical and structural investigations on phosphoribosylpyrophosphate synthetase from Mycobacterium smegmatis

Mycobacterium smegmatis represents one model for studying the biology of its pathogenic relative Mycobacterium tuberculosis. The structural characterization of a M. tuberculosis ortholog protein can serve as a valid tool for the development of molecules active against the M. tuberculosis target. In this context, we report the biochemical and structural characterization of M. smegmatis phosphoribosylpyrophosphate synthetase (PrsA), the ortholog of M. tuberculosis PrsA, the unique enzyme responsible for the synthesis of phosphoribosylpyrophosphate (PRPP). PRPP is a key metabolite involved in several biosynthetic pathways including those for histidine, tryptophan, nucleotides and decaprenylphosphoryl-arabinose, an essential precursor for the mycobacterial cell wall biosynthesis. Since M. tuberculosis PrsA has been validated as a drug target for the development of antitubercular agents, the data presented here will add to the knowledge of the mycobacterial enzyme and could contribute to the development of M. tuberculosis PrsA inhibitors of potential pharmacological interest.

The Inosine Monophosphate Dehydrogenase, GuaB2, Is a Vulnerable New Bactericidal Drug Target for Tuberculosis

VCC234718, a molecule with growth inhibitory activity against Mycobacterium tuberculosis (Mtb), was identified by phenotypic screening of a 15344-compound library. Sequencing of a VCC234718-resistant mutant identified a Y487C substitution in the inosine monophosphate dehydrogenase, GuaB2, which was subsequently validated to be the primary molecular target of VCC234718 in Mtb. VCC234718 inhibits Mtb GuaB2 with a Ki of 100 nM and is uncompetitive with respect to IMP and NAD+. This compound binds at the NAD+ site, after IMP has bound, and makes direct interactions with IMP; therefore, the inhibitor is by definition uncompetitive. VCC234718 forms strong pi interactions with the Y487 residue side chain from the adjacent protomer in the tetramer, explaining the resistance-conferring mutation. In addition to sensitizing Mtb to VCC234718, depletion of GuaB2 was bactericidal in Mtb in vitro and in macrophages. When supplied at a high concentration (≥125 μM), guanine alleviated the toxicity of VCC234718 treatment or GuaB2 depletion via purine salvage. However, transcriptional silencing of guaB2 prevented Mtb from establishing an infection in mice, confirming that Mtb has limited access to guanine in this animal model. Together, these data provide compelling validation of GuaB2 as a new tuberculosis drug target.

Essential but Not Vulnerable: Indazole Sulfonamides Targeting Inosine Monophosphate Dehydrogenase as Potential Leads against Mycobacterium tuberculosis

A potent, noncytotoxic indazole sulfonamide was identified by high-throughput screening of >100,000 synthetic compounds for activity against Mycobacterium tuberculosis (Mtb). This noncytotoxic compound did not directly inhibit cell wall biogenesis but triggered a slow lysis of Mtb cells as measured by release of intracellular green fluorescent protein (GFP). Isolation of resistant mutants followed by whole-genome sequencing showed an unusual gene amplification of a 40 gene region spanning from Rv3371 to Rv3411c and in one case a potential promoter mutation upstream of guaB2 (Rv3411c) encoding inosine monophosphate dehydrogenase (IMPDH). Subsequent biochemical validation confirmed direct inhibition of IMPDH by an uncompetitive mode of inhibition, and growth inhibition could be rescued by supplementation with guanine, a bypass mechanism for the IMPDH pathway. Beads containing immobilized indazole sulfonamides specifically interacted with IMPDH in cell lysates. X-ray crystallography of the IMPDH-IMP-inhibitor complex revealed that the primary interactions of these compounds with IMPDH were direct pi-pi interactions with the IMP substrate. Advanced lead compounds in this series with acceptable pharmacokinetic properties failed to show efficacy in acute or chronic murine models of tuberculosis (TB). Time-kill experiments in vitro suggest that sustained exposure to drug concentrations above the minimum inhibitory concentration (MIC) for 24 h were required for a cidal effect, levels that have been difficult to achieve in vivo. Direct measurement of guanine levels in resected lung tissue from tuberculosis-infected animals and patients revealed 0.5-2 mM concentrations in caseum and normal lung tissue. The high lesional levels of guanine and the slow lytic, growth-rate-dependent effect of IMPDH inhibition pose challenges to developing drugs against this target for use in treating TB.

An active site-tail interaction in the structure of hexahistidine-tagged Thermoplasma acidophilum citrate synthase

Citrate synthase (CS) plays a central metabolic role in aerobes and many other organisms. The CS reaction comprises two half-reactions: a Claisen aldol condensation of acetyl-CoA (AcCoA) and oxaloacetate (OAA) that forms citryl-CoA (CitCoA), and CitCoA hydrolysis. Protein conformational changes that `close' the active site play an important role in the assembly of a catalytically competent condensation active site. CS from the thermoacidophile Thermoplasma acidophilum (TpCS) possesses an endogenous Trp fluorophore that can be used to monitor the condensation reaction. The 2.2 Å resolution crystal structure of TpCS fused to a C-terminal hexahistidine tag (TpCSH6) reported here is an `open' structure that, when compared with several liganded TpCS structures, helps to define a complete path for active-site closure. One active site in each dimer binds a neighboring His tag, the first nonsubstrate ligand known to occupy both the AcCoA and OAA binding sites. Solution data collectively suggest that this fortuitous interaction is stabilized by the crystalline lattice. As a polar but almost neutral ligand, the active site-tail interaction provides a new starting point for the design of bisubstrate-analog inhibitors of CS.

Strict reaction and substrate specificity of AGXT2L1, the human O-phosphoethanolamine phospho-lyase

Dysregulated expression of the AGXT2L1 gene has been associated to neuropsychiatric disorders. Recently the gene product was shown to possess O-phosphoethanolamine phospho-lyase activity. We here analyze the specificity of AGXT2L1 in terms of both reaction and substrate. We show that the enzyme, despite having evolved from a transaminase ancestor, is at least 500-fold more active as a lyase than as an aminotransferase. Furthermore, the lyase reaction is very selective for O-phosphoethanolamine, strongly discriminating against closely related compounds, and we dissect the factors that contribute to such narrow substrate specificity. Overall, AGXT2L1 function appears to be rigidly confined to phospholipid metabolism, which is altered in neuropsychiatric disturbances.

The advantages of being locked. Assessing the cleavage of short and long RNAs by locked nucleic acid-containing 8-17 deoxyribozymes

RNA-cleaving deoxyribozymes can be used for the sequence-specific knockdown of mRNAs. It was previously shown that activity of these deoxyribozymes is enhanced when their substrate-binding arms include some locked nucleic acid (LNA) residues, but the mechanistic basis of this enhancement was not explored. Here we dissected the kinetics and thermodynamics underlying the reaction of LNA-containing 8-17 deoxyribozymes. Four 8-17 constructs were designed to target sequences within the E6 mRNA from human papillomavirus type 16. When one of these deoxyribozymes (DNAzymes) and the corresponding LNA-armed enzyme (LNAzyme) were tested against a minimal RNA substrate, they showed similar rates of substrate binding and similar rates of intramolecular cleavage, but the LNAzyme released its substrate more slowly. The superior thermodynamic stability of the LNAzyme-substrate complex led to improved performances in reactions carried out at low catalyst concentrations. The four DNAzymes and the corresponding LNAzymes were then tested against extended E6 transcripts (>500 nucleotides long). With these structured substrates, the LNAzymes retained full activity, whereas the DNAzymes cleaved extremely poorly, unless they were allowed to pre-anneal to their targets. These results imply that LNAzymes can easily overcome the kinetic barrier represented by local RNA structure and bind to folded targets with a faster association rate as compared with DNAzymes. Such faster annealing to structured targets can be explained by a model whereby LNA monomers favor the initial hybridization to short stretches of unpaired residues ("nucleation"), which precedes disruption of the local mRNA structure and completion of the binding process.

A threonine synthase homolog from a mammalian genome

The genomes of several vertebrates contain two genes encoding proteins highly similar to threonine synthase (TS), even though the biosynthesis of l-threonine (l-Thr) is not known to occur in these animals. We report a bioinformatic analysis of the two TS-like genes, the recombinant expression of one murine TS homolog (mTSH2) and its initial biochemical characterization. Recombinant mTSH2 contained bound pyridoxal-5'-phosphate (PLP), but did not synthesize l-Thr. The enzyme did, however, bind O-phospho-homoserine (PHS; the actual TS substrate) and degraded it to alpha-ketobutyrate, phosphate, and ammonia-a known side reaction of microbial TSs. mTSH2 also degraded O-phospho-threonine (PThr) to alpha-ketobutyrate, showing that it can act as a catabolic phospho-lyase on both gamma- and beta-phosphorylated substrates. These findings suggest an unusual evolutionary origin for mTSH2, whereby an original TS enzyme became 'recycled' into a phospho-lyase upon dismissal, in metazoa, of the l-Thr biosynthetic pathway.

Induction of apoptosis in Kaposi's sarcoma spindle cell cultures by the subunits of human chorionic gonadotropin

OBJECTIVES

Elucidation of the mechanisms of the previously shown growth-inhibitory action of human chorionic gonadotropin (hCG) on Kaposi's sarcoma (KS) cells and the role of the luteinizing hormone/hCG receptor (hCGR).

DESIGN AND METHODS

Analysis of KS tissues and cultured spindle-type KS cells for the presence of the hCGR using 125I-hCG binding and reverse transcriptase-polymerase chain reaction; analysis of several hCG preparations (urinary, recombinant, isolated alpha and beta subunits); analysis of apoptosis mechanisms by several assays including using z-Val-Ala-Asp-fluoromethylketone (zVAD-FMK), a known apoptosis-inhibitory drug.

RESULTS

First, we found that some urinary preparations of hCG (e.g., CG-10, Steris Profasi) were indeed KS-killing but others (such as Pregnyl, Choragon, Serono Profasi) were not. Secondly, recombinant subunits (alpha as well as beta) of hCG were KS cell-killing but recombinant intact hCG was not. Thirdly, the hCGR message and protein were undetectable in KS. Fourthly, CG10-induced cell death occurred by apoptosis and KS cells could be rescued by preincubation with zVAD-FMK. Finally, we also found that normal peripheral blood lymphocytes (PBL) were killed by CG-10.

CONCLUSION

It is proposed that the action of subunits or subunit fragments of hCG, mediated by a putative orphan receptor (as opposed to the hCGR) and executed by interleukin-1-converting enzyme (ICE)-like protease(s), constitutes a novel apoptosis mechanism effective towards KS cells, but PBLs and possibly other cells as well. These results provide a basis for testing in vitro the therapeutic efficacy of hCG preparations which, in turn, should improve current clinical trials with 'hCG' in patients who have KS.

Characterization of the major histocompatibility complex class II binding site on LAG-3 protein

The lymphocyte activation gene-3 (LAG-3), selectively transcribed in human activated T and NK cells, encodes a ligand for major histocompatibility complex (MHC) class II molecules. Like CD4, LAG-3 ectodomain is composed of four Ig-like domains (D1-D4). Nothing is known about the LAG-3 regions or residues required to form a stable MHC class II binding site. In contrast to CD4, soluble LAG-3 molecules stably interact with MHC class II molecules expressed on the cell surface. In addition, the first two N-terminal domains of soluble LAG-3 (D1 and D2) molecules, alone, are capable of binding MHC class II. From a LAG-3 model structure, we designed mutants and tested their ability to bind MHC class II molecules in an intercellular adhesion assay. We found residues on the membrane-distal, CDR1-2-containing top face of D1 that are essential for either binding or repulsing MHC class II proteins. Most of these residues are clustered at the base of a large extra-loop structure that is a hallmark of the LAG-3 D1 Ig-like domain. In addition, as for CD4, oligomerization of LAG-3 on the cell surface may be required to form a stable MHC binding site because mutation of three residues in the ABED beta-strands containing side of D1 results in a dominant negative effect (i.e., binding inhibition of coexpressed wild-type LAG-3).

The beta-core fragment of human chorionic gonadotrophin inhibits growth of Kaposi's sarcoma-derived cells and a new immortalized Kaposi's sarcoma cell line

OBJECTIVE

Kaposi's sarcoma (KS), a condition often associated with HIV infection, is more common in men than in women; pregnancy and sex hormones could be involved. Urinary human chorionic gonadotrophin (hCG) has been reported to inhibit the growth of KS cell lines, with great variability among preparations. Urinary hCG often contains free forms of the hCG subunits and a fragment of the free beta-subunit, the beta-core, which may have biological activity. We compared the effect of the beta-core fragment, the beta-subunit, recombinant and urinary hCG on KS immortal and spindle cells.

DESIGN AND METHODS

A new immortal KS cell line was phenotypically and karyotypically characterized. The effects on growth of this cell line and of primary KS spindle cells by hCG and its purified derivatives were tested. Induction of apoptosis was demonstrated using acridine orange/ethidium bromide staining.

RESULTS

The beta-core fragment harboured the most potent growth inhibitory activity on a molar basis. After 72 h of treatment with the beta-core, 60-70% of KS cells show apoptotic nuclei. No effects were observed on endothelial cells.

CONCLUSIONS

The beta-core fragment of hCG proved to be the most effective part of the hCG molecule, inducing growth inhibition and apoptosis of KS cells. Thus, the beta-core could be the most appropriate hCG derivative for the therapy of KS.

A highly precise reporter gene bioassay for type I interferon

We describe the setting up and validation of a reporter gene assay for type I IFN based on monkey Vero cells transfected with pMx-Luc, a plasmid carrying the luciferase gene under the control of the type I IFN inducible mouse Mx1 promoter. Vero cells were stably transfected with pMx-Luc and clone 3-143/5 was selected on the basis of luciferase inducibility by IFN-beta. A linear dose-response relationship was found between 1 and 16 IU/ml IFN-beta. The assay was shown to be specific for IFN-alpha and -beta as no effect by a number of other cytokines including IFN-gamma could be detected. In order to render the IFN-beta reporter gene assay protocol more suitable for routine assays, a 3 x 3 balanced parallel line assay design was applied using a 96-well luminometer for luminescence measurement. The assay was shown to be precise with a coefficient of variation of less than 9%. This assay is characterized by high precision coupled to high efficiency, as reflected by a very short assay duration (1 day), when compared to the classical cytopathic effect assays for IFNs and the previously published IFN reporter gene assay based on growth hormone measurement (Lleonart, R., Näf, D., Browning, H. and Weissmann, C. (1990) A novel, quantitative bioassay for type 1 interferon using a recombinant indicator cell line. Biotechnology 8, 1263-1267).

Cloning of murine LAG-3 by magnetic bead bound homologous probes and PCR (gene-capture PCR)

In recent years PCR-based gene cloning strategies have found wide application in molecular biology, due to the power, speed, and relative simplicity of the PCR methodology. We have set up a novel PCR cloning strategy to isolate homologous genes, which is based on the capture of the cDNA sequence(s) of interest with a biotinylated probe and streptavidin-coupled magnetic beads followed by PCR amplification of the selected molecules. This method does not require sequence information on 5' and 3' regions of the cDNA of interest and permits gene isolation to be sensitive, fast, simple, and specific even when the conventional screening procedures give rise to high backgrounds. By using this technique, which we propose to call gene-capture PCR (GC-PCR) cloning, we were able to isolate the full-length murine lymphocyte activation gene 3 (LAG-3) cDNA from total RNA of activated thymocytes. The GC-PCR technique represents a powerful tool for easy isolation not only of homologous genes from related species, but also of genes sharing conserved regions of suitable length, gene variants, and gene encoding proteins where only limited knowledge of the amino acid sequence exists.

Oncogene expression is modulated by recombinant human interferon-beta in human breast-cancer cells

The effect of recombinant human interferon-beta on growth and oncoprotein expression was investigated in several human breast-cancer cell lines with different characteristics. All cell lines tested were sensitive to the antiproliferative action of the drug, regardless of their estrogen sensitivity. The maximal inhibition of cell proliferation was seen after 6 days of treatment. In estrogen-sensitive CG-5 and ZR-75-1 cells, but not in MDA-MB-453 estrogen-insensitive cells, a reduction in c-myc and c-erbB2 oncoproteins occurred after 48-72 hr and became more pronounced after 120-168 hr of treatment, suggesting that this down-regulation is not direct but is mediated by undefined molecular mechanisms. The time-course of the IFN-mediated decrease in oncoproteins seems to indicate that this event is not strictly related to the IFN-regulation of cell proliferation. The expression of c-erbB2 and c-myc was also analyzed, after recombinant human interferon-beta treatment, at the mRNA level in CG-5 cells. Surprisingly, no statistically significant variation of c-erbB2 or of c-myc mRNA was found either before or after 120-168 hr. Thus, we surmise that the observed reduction of oncoproteins may be due to post-transcriptional mechanisms.

Determination of haptoglobin expression in IL-6 treated HepG2 cells by ELISA and by RNA hybridization--evaluation of a quantitative method to measure IL-6

Interleukin-6 (IL-6) is known to be an important modulator of acute phase (AP) protein expression in hepatocytes both in vivo and in vitro. In the present study the inducing activity of IL-6 on the expression of the AP protein haptoglobin (HP) by the human hepatoma cell line HepG2, has been evaluated. HP mRNA inducibility was analysed by Northern and slot-blot hybridization, while HP protein was detected by means of an ELISA procedure. A dose-response relationship from 0.3 to 4.8 ng/ml of a human recombinant IL-6 preparation derived from a Chinese hamster ovary (CHO) cell line was observed after 48 h of treatment. Comparable results were obtained by analysing both HP mRNA expression and HP protein secretion. Detectable induction of HP protein secretion was observed with as little as 25 pg/ml of IL-6. The effect of IL-6 was potentiated by dexamethasone, while an inhibition on HP mRNA inducibility could be prevented by lowering the foetal calf serum (FCS) concentration to 1%. Preliminary data indicate that neither IL-1 beta nor TNF-alpha were able to induce significantly HP mRNA expression and protein secretion. The activity ratio between two IL-6 preparations (from CHO and E. coli cells) obtained with a conventional IL-6 bioassay (i.e., T1165 cell growth assay) was comparable to that obtained in the induction of HP expression. The nominal specific activity of the CHO-derived IL-6 was two to three times higher with both responses.

Social support, adversities and emotional distress in an Italian community sample

The association of social support with emotional distress in relation to adversities such as social problems, physical health and undesirable life events was assessed in an Italian community sample of 222 men and 224 women. Univariate comparisons and logistic regression analyses showed that neither the quality of a confiding core relationship nor social support from kin confidants was related to adversities. In women only, social support from friend confidants exerted a statistically significant independent main effect together with social problems and undesirable life events in producing a greater probability of emotional distress. The implications of these findings are discussed considering the socio-cultural characteristics of Italian families and individual coping strategies.

Effect of natural beta-interferon on estrogen receptor mRNA of breast cancer cells

We have demonstrated that natural beta-interferon (beta-IFN) enhances estrogen receptor (ER) mRNA of a human breast cancer cell line, CG-5. Cells were sensitive to the effect of beta-IFN at concentrations ranging from 10 to 100 IU/ml. The increase of ER mRNA was seen after 48 hr of treatment in at least three separate experiments. Our results are in agreement with the previously observed enhancement of receptor protein. In addition, they suggest that the IFN-induced promotion of the antiproliferative activity of drugs which act via ER may be due, in part, to increased receptor synthesis.

Life events, social problems and physical health status as predictors of emotional distress in men and women in a community setting

The main aim of this study was to construct logistic models of emotional distress (defined as a GHQ-30 score of 6 or greater) in a community sample of 226 men and 225 women. The independent variables included were: sociodemographic characteristics, physical health status, social problems and undesirable life events. Univariate comparisons showed that in both sexes undesirable life events and social problems were associated with emotional distress; in men the presence of physical symptoms and widowed, separated or divorced status also showed such an association. Separate logistic regression models for men and women confirmed the importance of undesirable life events and social problems as predictors for emotional distress. In women there was also a significant interaction effect between the two variables on emotional distress. Sociodemographic characteristics and physical health status did not exert a statistically significant effect in these models.

The perception of social problems by husbands and wives in the community

The Social Problem Questionnaire (SPQ) was completed by 132 Italian married couples who were part of a stratified community sample of 207 families. Agreement between husbands and wives on problems in housing, finance, marriage, family and social relationships was assessed by product moment correlation coefficients, weighted kappas, specific agreement indices and three way analysis of variance. The results showed that couples agreed well on the absence but not on the presence of social problems. Although husbands' and wives' ratings on the severity of problems correlated significantly, wives consistently tended to give higher ratings than their husbands. The implications of these results for social research and community surveys are briefly discussed.

Family factors associated with the use of psychotropic drugs, alcohol abuse, and minor psychiatric morbidity in the community

The association of family health and family structure factors with psychotropic drug consumption, alcohol abuse, and minor psychiatric morbidity was investigated in a representative community sample of 151 respondents by means of a logistic multiple regression analysis. A General Health Questionnaire GHQ score of 5 or above was best predicted by undesirable events, sex, the number of generations, marital status, and the number of family members with a high GHQ score. Psychotropic drug consumption was best predicted by the number of family members with distress manifestations, while alcohol abuse in men was predicted best by events of the exit type.

Expression in Escherichia coli and characterization of human growth-hormone-releasing factor

A chemically synthesized DNA sequence, coding for the 44 amino acid residues of human growth-hormone-releasing factor (GRF) preceded by a tryptophan codon, was cloned in frame with Escherichia coli trpE gene within a pBR322-derived plasmid. GRF was expressed in E. coli as a fused polypeptide chain (TrpE-GRF) and then the GRF amino acid sequence was released from the fused protein by specific chemical cleavage at the tryptophan residue using o-iodosobenzoic acid. The thioether group of the methionine residue of GRF was converted in the sulfonium salt derivative, in order to prevent irreversible oxidation of methionine to the sulfone derivative by the o-iodosobenzoic acid reagent. GRF was purified by HPLC and characterized in terms of amino acid composition after acid hydrolysis, protein sequencing and gel electrophoretic behaviour. These data clearly established that the biosynthetic GRF was identical to the natural one, except for the lack of amidation at the carboxyl-terminal amino acid. Far-ultraviolet circular dichroism measurements established that both biosynthetic and natural GRF are devoid of secondary structure in aqueous solution at neutral pH, whereas both peptide samples achieve a high percentage of helical structure in the presence of trifluoroethanol.

Social factors associated with the use of psychotropic drugs: alcohol abuse and minor psychiatric morbidity in the community

The association of socio-demographic factors and life events with psychotropic drug consumption, alcohol abuse and minor psychiatric morbidity was investigated in a representative community sample of 181 respondents. The statistical model used was a logistic multiple regression analysis. Psychotropic drug use was best predicted by family size and employment status; alcohol abuse by sex, family size and "exit" events; and minor psychiatric morbidity by sex, marital status and undesirable life events.

Preparation of a partially desialylated human chorionic gonadotrophin (hCG) and its use for induction of ovulation after ovarian stimulation with human menopausal gonadotrophin

A method for the large scale preparation of partially desialylated human chorionic gonadotrophin suitable for human use is reported. To obtain the desired grade of desialylation and to avoid the presence of the enzyme in the modified hormone, neuraminidase coupled to Sepharose 4B was used. The preparation showed to be active in vitro (OAAD and SVW tests) and its half-life was found to be 13 min in the rat and 75 min in human beings. This desialo hCG proved to be effective in inducing ovulation in amenorrhoeic women. Among 39 induced cycles 31 ovulations and 5 pregnancies occurred.

Subunits of human chorionic gonadotrophin: immunological and biological studies

The alpha and beta subunits of human chorionic gonadotrophin (hCG) were prepared by incubation in 8 M urea, pH 4.5. The separation of the two subunits was obtained by DEAE-Sephadex A-25 chromatography and purification was carried out by gel filtration on Sephadex G-100. The beta subunit obtained was biologically active and was therefore further purified by affinity chromatography using as immuno-adsorbent the alpha antibodies coupled to Sepharose 4B. The beta subunit so purified showed a biological activity less than 1 IU/mg. The immunological and biological properties of the hCG subunits have been studied. It was found that the anti HCG beta serum can discriminate between hCG and hLH and that in the 125I-hCG + anti-beta serum radioimmunoassay, the cross-reactivity of pituitary hLH was lower than that of urinary hLH. Moreover, it was observed that the less purified was the urinary LH preparation, the higher was the cross-reactivity. Therefore we considered the hypothesis that during the purification of human menopausal gonadotrophin (hMG) some LH subunits or smaller immunoreactive fragments could have been discarded with the waste fractions. In order to test the validity of this hypophysis, all the protein fractions obtained during the purification of the hMG were gel-filtered on Sephadex G-100. The immunoreactivity of the effluents from the gel filtration was tested by hCG, hCG-beta, hCG-alpha and hLH radioimmunoassays. While the alpha reactive material was found in some fractions as a peak having the same Ve/Vo value as hCG-alpha, the beta reactive material presenude hMG fractions was not observed in other fractions. The cross-reactivity with the anti beta serum was very low and was found in the LH region of the gel chromatogram. Furthermore, the neutralization of the biological activity of hCG and of urinary and pituitary LH by the anti hCG beta serum was studied by incubating a fixed amount of the three hormones with increasing volumes of antiserum and measuring the LH ACTIVITY AFTER INCUBATION BY THE OADD test. It was observed that the anti hCG beta serum inhibits hCG more than urinary or pituitary LH.

Subunits of human chorionic gonadotrophin: an immunochemical study

The α and β subunits of HCG were prepared by urea-treatment of the hormone and isolated by DEAE-Sephadex A-25 chromatography. Further purification of the subunits was achieved by gel filtration on Sephadex G-100.

Partial chemico-physical characterization confirmed the non-identity of the HCG subunits, as previously reported by several investigators.

A radioimmunoassay (RIA) system based on 125I-HCG-β + anti-HCG-β serum was used to study the antigenic similarities between HCG, HCG-α and -β, human pituitary LH, urinary LH and FSH. The highest cross-reactivity was found for HCG, followed by HCG-α, LH and FSH.

The specificity of the above mentioned RIA system was increased by absorbing the anti-HCG-β serum with HCG-α. Because of the ability of this absorbed antiserum to discriminate between HCG and LH, a study was carried out to detect specifically HCG in urine in spite of the presence of physiological amounts of LH.

Radioimmunoassay employing polymerized antisera

Antisera made insoluble by polymerization were used for the radioimmunoassay of FSH and LH, as this was shown to be a useful method of separating bound and free labelled hormone.

Highly purified HCG and FSH, prepared in this laboratory, from urinary source were labelled with 125I. Antisera were raised by injecting urinary materials. The specificity of antisera was studied and some cross-reactivity was found between anti-urinary FSH and LH, but not with HCG. The sensitivity of LH and FSH radioimmunoassay was 1 mIU/ml and 3 mIU/ml, respectively.

Some determinations in dialyzed urine from various sources have also been performed and the preliminary results obtained are compared to those previously reported by others.

This paper discusses the radioimmunoassay of FSH and LH using a new solid-phase method, i. e. the use of polymerized antiserum, as previously described (Donini et al. 1968).

A new approach to the biological determination of the luteinizing hormone

The response of the uterine weight of immature mice to FSH and LH preparations with low contamination by each other was studied. The new approach to the biological assay of LH, which could be designated the »uterine-augmentation« test, was based on injecting intact immature mice with a constant dose (4.44 IU) of a biologically pure FSH preparation plus increasing amounts of extracts containing LH.

A dose as little as 0.068 IU of LH is capable to increase the uterine weight when injected together with 4.44 IU of biologically pure FSH. A significant uterine response can be obtained when animals are injected with 29.4 μg of 2nd IRP-HMG (equivalent to 0.128 IU-LH and 0.128 IU-FSH). When a constant dose of 4.44 IU of biologically pure FSH is added to each dose level of the 2nd IRP-HMG, a significant uterine response is obtained with 14.7 μg of this reference preparation. The end point was the mouse uterine weight.

Some determinations of the LH activity in urinary extracts have been performed according to this new method and from the results it seems that the LH activities, as determined by the ovarian ascorbic acid depletion method, agree with those determined by the uterine-augmentation test. It also seems that the uterine weight response is proportional to the LH activity and not dependent on the FSH-LH ratio of the samples assayed.