Safety of a controlled human infection model of tuberculosis with aerosolised, live-attenuated Mycobacterium bovis BCG versus intradermal BCG in BCG-naive adults in the UK: a dose-escalation, randomised, controlled, phase 1 trial

BACKGROUND

Mycobacterium tuberculosis is the main causative agent of tuberculosis. BCG, the only licensed vaccine, provides inadequate protection against pulmonary tuberculosis. Controlled human infection models are useful tools for vaccine development. We aimed to determine a safe dose of aerosol-inhaled live-attenuated Mycobacterium bovis BCG as a surrogate for M tuberculosis infection, then compare the safety and tolerability of infection models established using aerosol-inhaled and intradermally administered BCG.

METHODS

This phase 1 controlled human infection trial was conducted at two clinical research facilities in the UK. Healthy, immunocompetent adults aged 18-50 years, who were both M tuberculosis-naive and BCG-naive and had no history of asthma or other respiratory diseases, were eligible for the trial. Participants were initially enrolled into group 1 (receiving the BCG Danish strain); the trial was subsequently paused because of a worldwide shortage of BCG Danish and, after protocol amendment, was restarted using the BCG Bulgaria strain (group 2). After a dose-escalation study, during which participants were sequentially allocated to receive either 1 × 103, 1 × 104, 1 × 105, 1 × 106, or 1 × 107 colony-forming units (CFU) of aerosol BCG, the maximum tolerated dose was selected for the randomised controlled trial. Participants in this trial were randomly assigned (9:12), by variable block randomisation and using sequentially numbered sealed envelopes, to receive aerosol BCG (1 × 107 CFU) and intradermal saline or intradermal BCG (1 × 106 CFU) and aerosol saline. Participants were masked to treatment allocation until day 14. The primary outcome was to compare the safety of a controlled human infection model based on aerosol-inhaled BCG versus one based on intradermally administered BCG, and the secondary outcome was to evaluate BCG recovery in the airways of participants who received aerosol BCG or skin biopsies of participants who received intradermal BCG. BCG was detected by culture and by PCR. The trial is registered at ClinicalTrials.gov, NCT02709278, and is complete.

FINDINGS

Participants were assessed for eligibility between April 7, 2016, and Sept 29, 2018. For group 1, 15 participants were screened, of whom 13 were enrolled and ten completed the study; for group 2, 60 were screened and 33 enrolled, all of whom completed the study. Doses up to 1 × 107 CFU aerosol-inhaled BCG were sufficiently well tolerated. No significant difference was observed in the frequency of adverse events between aerosol and intradermal groups (median percentage of solicited adverse events per participant, post-aerosol vs post-intradermal BCG: systemic 7% [IQR 2-11] vs 4% [1-13], p=0·62; respiratory 7% [1-19] vs 4% [1-9], p=0·56). More severe systemic adverse events occurred in the 2 weeks after aerosol BCG (15 [12%] of 122 reported systemic adverse events) than after intradermal BCG (one [1%] of 94; difference 11% [95% CI 5-17]; p=0·0013), but no difference was observed in the severity of respiratory adverse events (two [1%] of 144 vs zero [0%] of 97; 1% [-1 to 3]; p=0·52). All adverse events after aerosol BCG resolved spontaneously. One serious adverse event was reported-a participant in group 2 was admitted to hospital to receive analgesia for a pre-existing ovarian cyst, which was deemed unrelated to BCG infection. On day 14, BCG was cultured from bronchoalveolar lavage samples after aerosol infection and from skin biopsy samples after intradermal infection.

INTERPRETATION

This first-in-human aerosol BCG controlled human infection model was sufficiently well tolerated. Further work will evaluate the utility of this model in assessing vaccine efficacy and identifying potential correlates of protection.

FUNDING

Bill & Melinda Gates Foundation, Wellcome Trust, National Institute for Health Research Oxford Biomedical Research Centre, Thames Valley Clinical Research Network, and TBVAC2020.

Genomic hybridization of bovine class II major histocompatibility genes: 1. Extensive polymorphism of DQ alpha and DQ beta genes

Class II genes of the bovine major histocompatibility complex (MHC) were investigated by Southern blot analysis using human cDNA probes for DQ alpha, DQ beta, DR alpha and DR beta. The presence of a DQ-like and a DR-like subregion in cattle was clearly indicated. Highly polymorphic restriction fragment patterns were obtained when genomic DNA, digested with any one of the BamHI, EcoRI or PvuII restriction enzymes, was hybridized with the DQ alpha and the DQ beta probe. The polymorphisms were interpreted genetically by analysing five paternal half-sib families of the Swedish Red and White breed. The material comprised, besides the bulls, 28 offspring and their dams. The analysis resolved 9 and 12 allelic variants of DQ alpha and DQ beta respectively. Thus, this investigation establishes a method for routine typing of MHC class II gene polymorphism in cattle. The results were entirely consistent with close linkage of DQ alpha and DQ beta since no recombinant was found and since alleles at these loci occurred in complete linkage disequilibrium in the material investigated. Close linkage between DQ and the blood group locus M, which has previously been found to be closely linked to the serologically defined BoLA-A locus, was also indicated. In this study DNA was isolated from frozen semen samples of dead bulls, which shows that this type of analysis will be useful in genetic investigations in cattle breeds, where artificial insemination is practised.

Genomic hybridization of bovine class II major histocompatibility genes: 2. Polymorphism of DR genes and linkage disequilibrium in the DQ-DR region

Class II genes of the bovine major histocompatibility complex have been investigated by Southern blot analysis using human cDNA probes for DQ alpha, DQ beta, DR alpha and DR beta. In this report restriction fragment length polymorphisms of DR alpha and DR beta are described. The polymorphisms were interpreted genetically by analysing five paternal half-sib families of the Swedish Red and White Breed, comprising altogether 28 offspring. Using the restriction enzymes BamHI, EcoRI and PvuII, three DR alpha and three DR beta allelic fragment patterns were resolved. The DR alpha and DR beta genes thus appear to be much less polymorphic than the previously described DQ alpha and DQ beta genes. Also, the observed linkage disequilibrium between DR genes was less pronounced than that between DQ genes, whereas the association between DR and DQ haplotypes was very strong. The family data available indicated strongly that the DQ alpha, DQ beta, DR alpha and DR beta genes are all closely linked.

Ectopic expression of EFFECTOR OF TRANSCRIPTION perturbs gibberellin-mediated plant developmental processes

The plant hormone gibberellin (GA) is known to modulate various aspects of plant cell differentiation and development. The current model of GA-mediated regulation is based on a de-repressible system and includes specific protein modification and degradation. HRT, a zinc finger protein from barley has been shown to have GA-dependent transcriptional repressing activity on the seed-specific alpha-amylase promoter [Raventos, D., Skriver, K., Schlein, M., Karnahl, K., Rogers, S.W., Rogers, J.C. and Mundy, J. 1998. J. Biol. Chem. 273: 23313-23320]. Here we report the characterization of a dicot homologue from Brassica napus (BnET) and provide evidence for its role in GA response modulation suggesting that this could be a conserved feature of this gene family. When BnET is ectopically expressed in either Arabidopsis or tobacco the phenotypes include dwarfism due to shorter internodes and late flowering, reduced germination rate, increased anthocyanin content and reduced xylem lignification as a marker for terminal cell differentiation. Transient expression in protoplasts supports the notion that this most likely is due to a transcriptional repression of GA controlled genes. Finally, histological analysis showed that in contrast to other GA deficient mutants the shorter internodes were due to fewer but not smaller cells, suggesting a function of BnET in GA-mediated cell division control.

No evidence for the ascorbic activation site of myrosinase being encoded by end of exon 9, beginning of exon 10

In summary, we conclude that MA and MB myrosinase genes contain the same set of 12 exons and that data neither support nor exclude the possibility that the portion of the enzyme encoded by exons 9 and 10 contains the ascorbate binding site of the molecule. Indeed, given the fact that both MA and MB myrosinase are activated by ascorbate, it is more reasonable to look for the ascorbate-binding site in areas conserved between the two sequences than in those that have diverged.

Different myrosinase and idioblast distribution in Arabidopsis and Brassica napus

Myrosinase (EC 3.2.3.1) is a glucosinolate-degrading enzyme mainly found in special idioblasts, myrosin cells, in Brassicaceae. This two-component system of secondary products and degradative enzymes is important in plant-insect interactions. Immunocytochemical analysis of Arabidopsis localized myrosinase exclusively to myrosin cells in the phloem parenchyma, whereas no myrosin cells were detected in the ground tissue. In Brassica napus, myrosinase could be detected in myrosin cells both in the phloem parenchyma and in the ground tissue. The myrosin cells were similar in Arabidopsis and B. napus and were found to be different from the companion cells and the glucosinolate-containing S-cells present in Arabidopsis. Confocal laser scanning immunomicroscopy analysis of myrosin cells in B. napus embryos showed that the myrosin grains constitute a continuous reticular system in the cell. These findings indicate that in the two species studied, initial cells creating the ground tissue have different potential for making idioblasts and suggest that the myrosinase-glucosinolate system has at least partly different functions. Several myrosinases in B. napus extracts are recovered in complex together with myrosinase-binding protein (MBP), and the localization of MBP was therefore studied in situ. The expression of MBP was highest in germinating seedlings of B. napus and was found in every cell except the myrosin cells of the ground tissue. Rapid disappearance of the MBP from the non-myrosin cells and emergence of MBP in the myrosin cells resulted in an apparent colocalization of MBP and myrosinase in 7-d-old seedlings.

The myrosinase-glucosinolate system in the interaction between Leptosphaeria maculans and Brassica napus

summary Leptosphaeria maculans causes blackleg disease, and resistance to this fungal pathogen is an important trait in the breeding of oilseed rape. A better comprehension of the role of the myrosinase-glucosinolate system in this context is of great value. The present study is the first to address effects on multiple components of this complex system, including concentrations of individual glucosinolates, product formation, myrosinase isoform distribution and activity, and levels of myrosinase binding proteins during the infection process. One resistant B. napus cultivar (Maluka) and one susceptible cultivar (Westar) were compared in the investigation. Our results show that the two cultivars had the same histological distribution, isoform expression, and activity of the myrosinase enzymes. The glucosinolate levels were also similar, with the exception of glucobrassicin and neoglucobrassicin, which were significantly lower in the resistant cultivar at 11 days post-infection. Growth of the fungus on the plant tissues did not alter glucosinolate levels, suggesting that L. maculans does not degrade these compounds. When the plants were starved of sulphur, and thereby depleted of glucosinolates, no increased susceptibility was observed. Hence, we suggest that the myrosinase-glucosinolate system does not determine the outcome of the interaction between B. napus and L. maculans.

Chromosomal distribution, localization and expression of the human endogenous retrovirus ERV9

ERV9 is a class I family of human endogenous retroviral sequences. Somatic cell hybrid genomic hybridization experiments using a mono-chromosomal panel indicate the presence of approximately 120 ERV9 loci in the human genome distributed on most chromosomes. Fluorescence in situ hybridization (FISH) using an ERV9 cDNA probe containing gag, pol and env sequences, verified this observation and a consistent signal was found at the chromosome region 11q13.3-->q13.5. By analysis of a panel of radiation hybrids, an ERV9 locus was mapped to within a 300-kbp region at the chromosome site 11q13. The marker cCLGW567 and the locus MAP3K11/D11S546 centromeric and telomeric flanked it, respectively. Northern blot analysis, using an ERV9 LTR probe, indicated that most normal tissues examined expressed low abundant ERV9 LTR driven mRNAs of various sizes. The most prominent expression was found in adrenal glands and testis. However, the level of expression varied in the same tissues among different individuals indicating that ERV9 mRNA expression probably is inducible in certain tissues or at various cell stages.

Transactivation of the Brassica napus napin promoter by ABI3 requires interaction of the conserved B2 and B3 domains of ABI3 with different cis-elements: B2 mediates activation through an ABRE, whereas B3 interacts with an RY/G-box

The transcriptional activator ABI3 is a key regulator of gene expression during embryo maturation in crucifers. In monocots, the related VP1 protein regulates the Em promoter synergistically with abscisic acid (ABA). We identified cis-elements in the Brassica napus napin napA promoter mediating regulation by ABI3 and ABA, by analyzing substitution mutation constructs of napA in transgenic tobacco plantlets ectopically expressing ABI3. In transient analysis using particle bombardment of tobacco leaf sections, a tetramer of the distB ABRE (abscisic acid-responsive element) mediated transactivation by ABI3 and ABI3-dependent response to ABA, whereas a tetramer of the composite RY/G complex, containing RY repeats and a G-box, mediated only ABA-independent transactivation by ABI3. Deletion of the conserved B2 and B3 domains of ABI3 abolished transactivation of napA by ABI3. The two domains of ABI3 interact with different cis-elements: B2 is necessary for ABA-independent and ABA-dependent activations through the distB ABRE, whereas B3 interacts with the RY/G complex. Thus B2 mediates the interaction of ABI3 with the protein complex at the ABRE. The regulation of napA by ABI3 differs from Em regulation by VP1, in that the B3 domain of ABI3 is essential for the ABA-dependent regulation of napA.

A mutation in PRKAG3 associated with excess glycogen content in pig skeletal muscle

A high proportion of purebred Hampshire pigs carries the dominant RN- mutation, which causes high glycogen content in skeletal muscle. The mutation has beneficial effects on meat content but detrimental effects on processing yield. Here, it is shown that the mutation is a nonconservative substitution (R200Q) in the PRKAG3 gene, which encodes a muscle-specific isoform of the regulatory gamma subunit of adenosine monophosphate-activated protein kinase (AMPK). Loss-of-function mutations in the homologous gene in yeast (SNF4) cause defects in glucose metabolism, including glycogen storage. Further analysis of the PRKAG3 signaling pathway may provide insights into muscle physiology as well as the pathogenesis of noninsulin-dependent diabetes mellitus in humans, a metabolic disorder associated with impaired glycogen synthesis.

Pathophysiology of primary hyperparathyroidism

Parathyroid gland is the overall regulatory organ within the systemic calcium homeostasis. Through cell surface bound calcium-sensing receptors external calcium inversely regulates release of parathyroid hormone (PTH). This mechanism, which is voltage independent and most sensitive around physiologic calcium concentrations, is regulated through a 120 kDa calcium sensing receptor, CaR. Inherited inactivation of this receptor is the cause for familial hypocalciuric hypercalcemia (FHH). Parallel research identified the 550 kDa glycoprotein megalin, which also is expressed on the parathyroid cell surface, as another potential calcium sensing protein. Although this protein expresses numerous calcium binding sites on its external domain, its main function may be calcium sensitive binding and uptake of steroid hormones, such as 25-OH-vitamin D3 (bound to vitamin D binding protein) and retinol. In hyperparathyroidism (HPT), excessive PTH is secreted and the calcium sensitivity of the cells reduced, i.e. the set-point, defined as the external calcium concentration at which half-maximal inhibition of PTH release occurs, shifted to the right. Pathological cells have reduced expression of both CaR and megalin, and reduced amount of intracellular lipids, possibly including stored steroid hormones. A number of possible genetic disturbances have been identified, indicating multifactorial reasons for the disease. In postmenopausal women, however, the individual group with highest incidence of disease, a causal relation to reduced effect of vitamin D is possible. An incipient renal insufficiency with age, lack of sunshine in the Northern Hemisphere, and an association to the baT haplotype of the vitamin D receptor supports this theory. This review summarizes data on regulation of PTH release, dysregulation in HPT, as well as proliferation of parathyroid cells.

Gene regulation during late embryogenesis: the RY motif of maturation-specific gene promoters is a direct target of the FUS3 gene product

The Arabidopsis mutants fus3 and abi3 show pleiotropic effects during embryogenesis including reduced levels of transcripts encoding embryo-specific seed proteins. To investigate the interaction between the B3-domain-containing transcription factors FUS3 and ABI3 with the RY cis-motif, conserved in many seed-specific promoters, a promoter analysis as well as band-shift experiments were performed. The analysis of promoter mutants revealed the structural requirements for the function of the RY cis-element. It is shown that both the nucleotide sequence and the alternation of purin and pyrimidin nucleotides (RY character) are essential for the activity of the motif. Further, it was shown that FUS3 and ABI3 can act independently of each other in controlling promoter activity and that the RY cis-motif is a target for both transcription factors. For FUS3, which is so far the smallest known member of the B3-domain family, a physical interaction with the RY motif was established. The functional and biochemical data demonstrate that the regulators FUS3 and ABI3 are essential components of a regulatory network acting in concert through the RY-promoter element to control gene expression during late embryogenesis and seed development.

Myrosinase: gene family evolution and herbivore defense in Brassicaceae

Glucosinolates are a category of secondary products present primarily in species of the order Capparales. When tissue is damaged, for example by herbivory, glucosinolates are degraded in a reaction catalyzed by thioglucosidases, denoted myrosinases, also present in these species. Thereby, toxic compounds such as nitriles, isothiocyanates, epithionitriles and thiocyanates are released. The glucosinolate-myrosinase system is generally believed to be part of the plant's defense against insects, and possibly also against pathogens. In this review, the evolution of the system and its impact on the interaction between plants and insects are discussed. Further, data suggesting additional functions in the defense against pathogens and in sulfur metabolism are reviewed.

Myrosinase: gene family evolution and herbivore defense in Brassicaceae

Glucosinolates are a category of secondary products present primarily in species of the order Capparales. When tissue is damaged, for example by herbivory, glucosinolates are degraded in a reaction catalyzed by thioglucosidases, denoted myrosinases, also present in these species. Thereby, toxic compounds such as nitriles, isothiocyanates, epithionitriles and thiocyanates are released. The glucosinolate-myrosinase system is generally believed to be part of the plant's defense against insects, and possibly also against pathogens. In this review, the evolution of the system and its impact on the interaction between plants and insects are discussed. Further, data suggesting additional functions in the defense against pathogens and in sulfur metabolism are reviewed.

Age-dependent wound induction of a myrosinase-associated protein from oilseed rape (Brassica napus)

In order to study the expression of the induced form of myrosinase-associated protein (iMyAP), a genomic clone encoding the protein was isolated from Brassica napus. The coding portion of the gene was found to consist of five exons separated by one long intron of 938 bp and three shorter introns of ca. 100 bp. A 1.9 kb promoter fragment including the 5'-untranslated region was cloned in front of the coding portion of the Escherichia coli iudA gene and transformed into Arabidopsis thaliana. Expression was observed in hypocotyls of 4-day seedlings, but in 7-day seedlings the iMyAP promoter did not direct expression. In flowering plants, only the abscission zone of the young silique displayed promoter activity. In contrast, mechanical wounding of 7-day seedlings induced a systemic expression in all cells of the cotyledons. Wounding of 14-day seedlings gave rise to systemic induced expression mainly in the vascular tissue. However, mechanical wounding and wounding by flea beetles (Phyllotreta undulata) of 4-week old plants only gave rise to a local induction of the promoter, suggesting that the systemic signal system is age-dependent. Methyl jasmonate also induced iMyAP expression. In situ and northern analysis of iMyAP transcripts in young leaves of B. napus showed that the induction was high after 1 h and absent after 24 h. Comparison of the effect of different types of wounding on the iMyAP promoter induction in transgenic Arabidopsis showed that similar degrees of local induction were achieved regardless of the degree of macerated tissue left on the plant.

Interaction between composite elements in the napA promoter: both the B-box ABA-responsive complex and the RY/G complex are necessary for seed-specific expression

During seed maturation, the transcriptional activity of napin genes is regulated by developmental signals involving the transcriptional activator ABI3 and abscisic acid (ABA). To localize cis elements involved in the seed-specific activity of the napin napA promoter, a systematic analysis was performed focusing on two major element complexes, the B-box and RY/G. Substitution mutation analysis using promoter-reporter gene fusions in stable transgenic tobacco showed synergistic interactions between elements within these complexes. The distal part of the B-box shows similarities to abscisic acid response elements and the proximal portion contains a CA-rich element. In vitro studies involving Exonuclease III protection and electrophoretic mobility shift assays revealed binding by nuclear proteins to elements within the B-box. The distal and proximal parts of the B-box were found to bind distinct nuclear protein complexes. By gain-of-function analysis with a tetramer of the B-box fused to a truncated (-46) cauliflower mosaic virus (CaMV) 35S minimal promoter, it was demonstrated that the B-box mediates strong activity in seeds. Further, it was shown that the elements in the B-box constitute an ABA-responsive complex, since the B-box tetramer mediates ABA-responsiveness in vegetative tissues to a construct containing the CaMV virus 35S enhancer (-343 to -90). Thus, the seed-specific activity of the napA promoter relies on the combinatorial interaction between the RY/G complex and the B-box ABA-responsive complex during the ABA response in seed development.

Effects of extracellular calcium on the subcellular translocation of bovine parathyroid PKC isozymes

The release of parathyroid hormone is regulated by the extracellular concentration of Ca2+ through a sensor(s) on the surface of the parathyroid cells, but few details are known on the further relay of the signal inside the cell. Activation of protein kinase C (PKC) isozymes is associated with their translocation from the cell soluble fraction to the particulate fraction of the cell. Therefore, identification of a subcellular localization of a PKC isozyme in parathyroid cells as a response to changes in extracellular Ca2+ should be an indication for its putative role in signal transduction coupled to the Ca2+ sensor. We have determined the subcellular localization of six PKC isozymes (alpha, betaI, betaII, epsilon, zeta, and iota) in nonstimulated parathyroid cells and in those treated with low (0.5 mM) and high (3.0 mM) extracellular Ca2+ by confocal microscopy. At the physiological concentration of serum Ca2+, all PKC isozymes studied were localized mainly to the cytosol, although to different extents. Low extracellular Ca2+ caused a redistribution of PKCalpha to the periphery of the cells. In contrast, PKCbetaI, -epsilon, -zeta, and -iota were translocated to the periphery of the cells at high extracellular Ca2+. These results indicate that PKCalpha, -betaI, -epsilon, -zeta, and -iota are involved in the response of parathyroid cells to changes in extracellular Ca2+.

The role of protein kinase C signaling in activated DRA transcription

Expression of human MHC HLA-DRA class II gene can be up-regulated in B cells by Ig cross-linking as well as by phorbol esters such as 12-O-tetradecanoyl phorbol 13-acetate (TPA). Induced DRA expression involves activation of restricted protein kinase C (PKC) isoforms, resulting in activated activator protein-1-dependent transcription. In this report expression profiles and activation of PKC were analyzed in human Raji B lymphoblastoid cells. Transient transfection analysis with target plasmids containing either DRA promoter (wild-type or mutated) or TPA response elements demonstrated that pretreatment with the selective PKC inhibitor GF 109203X repressed TPA-mediated activation. Western analysis performed on cellular fractions of resting cells and of TPA-activated cells revealed abundant expression of classical PKC-alpha (cPKC-alpha), cPKC-betaII, and atypical PKC-zeta isoforms and identified a sustained translocation of cPKC-alpha and cPKC-betaII from the cytosolic compartment to membranes. As expected, the distribution of atypical PKC-zeta was unaffected by TPA treatment and displayed an even distribution between cytosol and membranes. This finding was confirmed by immunofluorescence microscopy. The TPA-mediated translocation of cPKC-alpha and cPKC-betaII was not influenced by pretreatment with GF 109203X. Finally, functional activation and translocation of PKC were investigated with a selective in vitro kinase assay. Together, these results show that activated HLA-DRA expression in response to TPA treatment is strictly dependent on PKC activation acting on the X2 box of the DRA promoter and that selective inhibition of PKC enzymatic activity does not influence subcellular localization of expressed PKC isoenzymes. Thus, the translocation event per se occurs independently of PKC activation in these cells.

Molecular cloning and characterization of starch-branching enzyme II from potato

Full-length cDNA for starch branching enzyme (SBE) II of potato was isolated and sequenced. In potato, similarly to most other investigated plants, the SBE-II isoform differs from SBE-I by having an acidic amino-terminal extension and a shorter carboxyterminus. Two forms of SBE-II, migrating as 98 and 95 kDa proteins in 6% SDS-polyacrylamide gels, were associated to tuber starch. The latter form was 16 amino acids shorter in the amino terminus. Transcript of SBE-II was present in leaf tissue, whereas significant expression was not seen in tubers. On the other hand, a significant amount of SBE-I transcript was detected in tuber tissue but not in leaves.

Retroelements in the human MHC class II region

Molecular genetic studies of the human major histocompatibility complex (MHC) have led to the identification of more than 200 genes. Besides the large number of genes in the MHC, densely clustered areas of retroelements have been identified. These include short and long interspersed elements (SINEs and LINEs), and human endogenous retroviruses (HERVs). The presence of retroelements in the MHC provides a clear example of how these elements affect the genome plasticity of the host. Comparative analyses of these retroelements have proven highly useful in evolutionary studies of the MHC. Recently, HERV-encoded superantigens have been implicated as candidate autoimmune genes in type I diabetes and multiple sclerosis. In addition, genetic analyses have revealed that autoimmune diseases show strong associations with MHC class II genes. The intriguing correlations between retroviral encoded antigens, MHC class II genes and the development of autoimmune disease merit intense future investigations of retroelements, in particular those endogenous retroviruses located in the MHC class II region proper.

The myrosinase-binding protein from Brassica napus seeds possesses lectin activity and has a highly similar vegetatively expressed wound-inducible counterpart

This communication demonstrates that proteins in the family of myrosinase-binding proteins (MBP) present in seeds of Brassica napus possess lectin activity, binding most efficiently to p-aminophenyl alpha-D-mannopyranoside-agarose, and to some extent to N-acetylglucosamine-agarose. A cDNA encoding a vegetatively expressed, wound-inducible counterpart to these seed MBP was isolated and characterised. Upon wounding, this MBP transcript accumulated in old and young leaves, and was systemically expressed in the young plant. Additionally, the wound-induced MBP transcript increased in abundance after treating the young plants with methyl jasmonate (MeJA), jasmonic acid (JA) or abscisic acid (ABA), and to some extent in response to the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. Expression induced by wounding, ABA or JA was antagonised by simultaneous feeding of the plants with salicylic acid. MBP polypeptides accumulated in MeJA-treated plants. The myrosinases redistributed from the soluble fraction into the insoluble fraction of a tissue extract after induction. The most abundant MBP (94 kDa) partitioned in the insoluble fraction, while two larger MBP (103 kDa and 108 kDa) were present only in the soluble fraction of extracts obtained from the control or MeJA-treated plant tissues.

Molecular cloning and N-terminal analysis of bovine cystatin C. Identification of a full-length N-terminal region

The N-terminal region of human cystatin C has been shown to be of crucial importance for the interaction of the inhibitor with cysteine proteinases. However, several studies have been unable to identify the corresponding region in bovine cystatin C, indicating that the binding of proteinases to the bovine inhibitor may not be dependent on this region. With the aim to resolve this apparent discrepancy and to elucidate the relation of bovine cystatin C to other cystatins, we have isolated a cDNA clone encoding bovine precystatin C. The sequence of this cDNA was similar to that of the human inhibitor and showed a putative signal peptidase cleavage site consistent with the N-terminal regions of the bovine and human inhibitors being of comparable size. This suggestion was verified by determination of the relative molecular mass of the mature bovine inhibitor isolated from cerebrospinal fluid under conditions minimising proteolysis. The N-terminal of the purified inhibitor was blocked, but the sequence of the N-terminal peptide produced by digestion with endopeptidase LysC could be unequivocally determined by tandem mass spectroscopy. Together, these results show that bovine cystatin C has 118 residues, in contrast with 110-112 residues reported previously, and has an N-terminal region analogous to that of human cystatin C. This region presumably is of similar importance for tight binding of target proteinases as in the human inhibitor.

Cloning of a putative G-protein-coupled receptor from Arabidopsis thaliana

We have cloned and characterized a cDNA from Arabidopsis thaliana that most likely encodes a novel member of the vast superfamily of G-protein-coupled receptor proteins (GPCRs). By taking advantage of amino acid sequence similarities between plant expressed sequence tags (ESTs) and established G-protein-coupled receptor sequences, a probe was obtained which was used for the screening of an Arabidopsis cDNA library. The cDNA which was found is very infrequently represented in the cDNA library, suggesting a low and/or spatially restricted expression. A region of the translated sequence of the cDNA shows the highest similarity to cAMP receptors from the slime mold Dictyostelium discoideum. The same region is also similar to that in members of the animal calcitonin family of receptors. Another region of the putative receptor, however, is similar to sequences of serotonin receptors and other receptors of the so-called rhodopsin family of GPCRs. The rhodopsin family has numerous members in higher vertebrate species. Alignments and phylogenetic analyses of the regions of similarity yielded results in accordance with other evolutionary considerations. Our cDNA thus occurred on a distinct major branch in relation to the rest of the rhodopsin family. In relation to the calcitonin family, our cDNA and cAMP receptors occurred together on a distinct major branch but appear to have diverged from each other shortly after their divergence from the rest of the calcitonin family. Other features further argue for a tentative identification of it as a GPCR. It displays seven discrete and strongly predicted transmembrane domains when analyzed in hydropathy plots. The preferred orientation is with the amino terminus towards the outside. It has one Cys residue in extracellular loop 1 and another in extracellular loop 2. Cys residues in these loops are known to form disulfide bridges in many other GPCRs. Finally, it has several fully conserved amino acids that belong to the most conserved in previously known GPCRs, that occur in the above regions of similarity.

Aberrantly expressed cytokeratin 1, a tumor-associated autoantigen in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is a somewhat puzzling disease, combining a propensity to metastasize with an indolent clinical course. The often pronounced T cell-dominated inflammatory infiltrate seen in PTC tumors has prompted us to search for signs of a tumor-induced immune response. In previous studies, we have demonstrated large tumor-specific deposits of IgG and complement in PTC tissue and isolated a putative target antigen. This investigation examines the presence of autoantibodies to cytokeratin 1, a high m.w. cytokeratin normally expressed only in suprabasal keratinocytes, in the serum and tumor tissue of PTC patients. Using immunoprecipitation and Western blot, cytokeratin 1-reactive autoantibodies were demonstrated in 80% of the PTC sera tested, and tumor-derived antibodies were shown to precipitate cytokeratin 1. Using immunohistochemistry, cytokeratins 1 and 10 were found in a large proportion of PTC tumors (39/44) but were absent from normal thyrocytes of most PTC-bearing glands. Our results indicate that this protein is expressed aberrantly in neoplastic cells and is immunogenic in this context.

Regulation of the wound-induced myrosinase-associated protein transcript in Brassica napus plants

Two slightly differing cDNA clones corresponding to the wound-inducible form of a previously characterized seed myrosinase-associated protein (MyAP) have been isolated from Brassica napus L. The transcripts corresponding to the induced MyAP (iMyAP) were found to be developmentally regulated in various vegetative organs. Both young and old leaves exhibited wound-inducible iMyAP expression. Furthermore, in the young plant, wounding resulted in a systemic increase in leaves located both acropetally and basipetally to the wounded leaf. Also, the iMyAP transcripts were induced by methyl jasmonate, jasmonic acid and abscisic acid. The different inductions could be antagonized by salicylic acid. A general responsiveness in methyl-jasmonate-treated leaves was demonstrated by in situ hybridization. No effect on the amount of iMyAP transcript was detected after feeding the plants with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. The similarity between MyAP and a lipase from Arabidopsis thaliana indicated a possible function in liberating acylated glucosinolates from their acyl group, thereby making them available for hydrolysis by the myrosinase enzymes. We also report on a reduction in the amount of myrosinase transcripts derived from the vegetatively expressed MB-gene family after treatment with exogenously applied salicylic acid or abscisic acid.

Tissue distribution of human gp330/megalin, a putative Ca(2+)-sensing protein

We used riboprobes and monoclonal antibodies to characterize tissue distribution of the human 550-kD homologue to gp330/megalin, primarily identified in the rat kidney. Human gp330/megalin mRNA and protein are readily identified in human parathyroid cells, placental cytotrophoblasts, kidney proximal tubule cells, and epididymal epithelial cells. The immunoreactivity is found on the surface of the cells and is heterogeneously downregulated in parathyroid hyperplasia and adenomas. Cells of the proximal kidney tubule and epididymis express the protein on their luminal aspect. Moreover, the protein is expressed in Type II pneumocytes, mammary epithelial and thyroid follicular cells, and the ciliary body of the eye. Sequence analysis of cDNA fragments, obtained by RT-PCR, revealed identical nucleotide sequences in parathyroid, kidney, placenta, epididymis, and lung. Immunohistochemistry for parathyroid hormone-related protein (PTHrP) revealed partial co-expression with human gp330/megalin in parathyroid, placenta, and mammary gland. The findings substantiate human gp330/megalin expression in a variety of human tissues expected to possess calcium-sensing functions. It may constitute a protein of utmost importance to adult and fetal calcium homeostasis, although other important functions may also be coupled to this exceptionally large protein with highly restricted tissue distribution.

Myrosinase-binding proteins are derived from a large wound-inducible and repetitive transcript

Several non-myrosinase proteins have been found in association with some of the myrosinases extracted from rape (Brassica napus) seed. Most of these proteins seemed to belong to a large family of proteins ranging in size over approximately 30-110 kDa, namely the myrosinase-binding protein (MBP) family. Potentially all of these MBPs might be derived from a single large precursor, encoded by a 3.3-kb transcript. This transcript coded for a 99-kDa glycine-rich protein with a highly repetitive structure. The mature 50-kDa and 52-kDa MBP amino-terminal was located 255 amino acids from the putative initiation methionine. Also, a more divergently related transcript, the protein product of which was unknown, has been cloned. However, the largest open reading frame suggested a proline-rich protein. While this transcript seemed to be expressed predominantly in seeds, the MBP transcripts were expressed in several tissues and also exhibited a responsiveness to wounding and methyl jasmonate. Both proteins exhibited significant similarities to lectins from Artocarpus integer and from Maclura pomifera.

Structural comparison of the precursor and the mature form of napin, the 2S storage protein in Brassica napus

The 2S storage protein napin from Brassica napus var. L. is synthesised as a precursor protein at the endoplasmic reticulum and transported along a gradient of decreasing pH to the vacuole, where two propeptides are removed to produce mature napin. The structures of pronapin expressed in insect cells and mature napin from rape seed were characterised. Limited proteolysis with several endoproteases cleaved primarily in the propeptides, suggesting that the propeptides are exposed to the exterior of the protein. Immunological comparison in parallel with circular dichroic spectrometry, both at neutral and acid pH, indicated that the propeptides had only a minor influence on the conformation of the regions of the molecule that correspond to mature napin.

Functional dissection of a napin gene promoter: identification of promoter elements required for embryo and endosperm-specific transcription

The promoter region (-309 to +44) of the Brassica napus storage protein gene napA was studied in transgenic tobacco by successive 5' as well as internal deletions fused to the reporter gene GUS (beta-glucuronidase). The expression in the two main tissues of the seed, the endosperm and the embryo, was shown to be differentially regulated. This tissue-specific regulation within the seed was found to affect the developmental expression during seed development. The region between -309 to -152, which has a large effect on quantitative expression, was shown to harbour four elements regulating embryo and one regulating endosperm expression. This region also displayed enhancer activity. Deletion of eight bp from position -152 to position -144 totally abolished the activity of the napA promoter. This deletion disrupted a cis element with similarity to an ABA-responsive element (ABRE) overlapping with an E-box, demonstrating its crucial importance for quantitative expression. An internal deletion of the region -133 to -120, resulted in increased activity in both leaves and endosperm and a decreased activity in the embryo. Within this region, a cis element similar to the (CA)n element, found in other storage protein promoters, was identified. This suggest that the (CA)n element is important for conferring seed specificity by serving both as an activator and a repressor element.

The multiple forms of starch-branching enzyme I in Solanum tuberosum

Western blot analysis showed the presence of three forms of starch-branching enzyme (SBE), with apparent molecular masses of 103, 97 and 80 kDa, in extracts of leaves and stored tubers of Solanum tuberosum. The 80-kDa form was absent in extracts of fresh tuber. Active 80-kDa enzyme was partially purified from stored tubers and sequence analysis showed that it, similar to the two larger enzyme forms, was an SBE-I isoform. Limited proteolysis of isolated 103-kDa SBE-I under native conditions removed approximately 200 amino acid residues from the carboxy terminus. A stable intermediate with an apparent molecular mass of approximately 80 kDa was formed. Since the 80-kDa form displayed full enzymatic activity and its circular-dichroism spectrum did not differ significantly from that of the 103-kDa enzyme, the carboxy-terminal portion of the enzyme was suggested to have an extended, unordered structure and therefore to be easily accessible to proteolysis. A cDNA sequence encoding a mature SBE-I was amplified from tuber mRNA of S. tuberosum by means of PCR. The 3' end of this sequence differed significantly from that of previously published data. PCR amplification and DNA sequencing of the 3' ends of the sbeI gene showed that four sbeI alleles exist in the cultivar studied. Two of these four alleles, sbeia and sbeIb, had slightly longer 3' ends compared with the other two, sbeIc and sbeId. The difference between the two groups of alleles was due to a partial deletion in sbeIc and sbeId of a segment duplicated in all alleles. All four alleles were expressed in leaf and tuber.

Identification of a 35 kD tumor-associated autoantigen in papillary thyroid carcinoma

Despite its tendency to metastasize and grow multifocally, papillary thyroid carcinoma (PTC), the most common endocrine malignancy, usually displays an indolent clinical course. Although this behavior probably reflects the inherent low growth potential of PTC cells, it has been postulated that the striking inflammatory reaction often present in PTC represents the activation of a protective, tumor-induced immune response. In a recent immunohistochemical study, we reported that immunoglobulin (IgG) and complement (C3d, C4d and C5) are specifically deposited in PTC tumor tissue. Endeavors were then made to isolate and identify tumor-associated antigens. Immunoprecipitation employing the serum and tumor tissue of PTC patients produced two bands by SDS-PAGE, at approximately 34.5 and 35 kD, which were not present in normal thyroid tissue. Three tryptic peptides of the 35 kD band were sequenced, identifying it as a fragment of cytokeratin 1, a structural protein not normally expressed in the thyroid. The results indicate a tumor-specific antibody response against an aberrantly expressed protein in PTC.

Sequence analysis and regulation of a gene encoding a cuticle-degrading serine protease from the nematophagous fungus Arthrobotrys oligospora

The nematode trapping fungus Arthrobotrys oligospora produces an extracellular serine protease (designated PII) that immobilizes free-living nematodes in bioassays and hydrolyses proteins of the nematode cuticle. Peptides were isolated from PII and partly sequenced. Three internal peptide sequences were used to design synthetic oligonucleotides, which allowed the subsequent isolation of the gene encoding PII from a genomic library. The deduced amino acid sequence indicated that PII is synthesized as a preproenzyme containing the mature enzyme, a signal sequence and a propeptide that are removed before the enzyme is secreted into the medium. The primary sequence of PII displayed a high degree of similarity with several other serine proteases of ascomycetes belonging to the subtilisin family. Northern analysis demonstrated that PII was expressed when the fungus was starved of nitrogen and carbon and that the expression was significantly stimulated by the addition to the medium of various soluble and insoluble proteins, including fragments of nematode cuticle. The levels of the mRNA as well as the proteolytic activity of PII were repressed in the presence of more easily metabolized forms of nitrogen (including ammonia, nitrate and amino acids) or glucose. The activity of the enzyme was almost completely inhibited by the peptide Phe-Val, as well as by the amino acid Phe, without a corresponding decrease in mRNA level. Notably, peptides with similar structures are known to be secreted by the host (nematode) and to stimulate the production of infection structures (traps) of the fungus.

Cloning and sequencing of human gp330, a Ca(2+)-binding receptor with potential intracellular signaling properties

We present here the complete primary structure of human gp330, the human variant of the principal kidney autoantigen causing Heymann membranous glomerulonephritis in rats. The deduced 4655 amino acid residues give a calculated molecular mass of 519636 Da for the mature protein and consists of a probable 25-amino-acid N-terminal signal peptide sequence, an extracellular region of 4398 amino acids, a single transmembrane-spanning domain of 23 amino acids, and an intracellular C-terminal region of 209 amino acid residues. Three types of cysteine-rich repeats characteristic of the low density lipoprotein receptor (LDLR) superfamily are present in human gp330. In the extracellular region, there are a total of 36 LDLR ligand-binding repeats, comprising four distinct domains, 16 growth factor repeats separated by eight YWTD spacer regions, and one epidermal growth factor-like repeat. No consensus cleavage sequence for the processing endoprotease furin is detected in human gp330. The intracellular tail contains not only two copies of the F(X)NPXY coated-pit mediated internalization signal characteristic of LDLR superfamily members, but also intriguing and potentially functional motifs including several Src-homology 3 recognition motifs, one Src-homology 2 recognition motif for the p85 regulatory subunit of phosphatidylinositol 3-kinase, and additional sites for protein kinase C, casein kinase II and cAMP-/cGMP-dependent protein kinase. There is approximately 77% amino acid identity between human and rat gp330 with minor differences between the extracellular and intracellular regions. Recently gp330 has been implicated in Ca2+ regulation in the parathyroid, the placenta, and the renal tubule, but its overall physiological and pathological role still remains uncertain.

Molecular characterization of a saline-soluble lectin from a parasitic fungus. Extensive sequence similarities between fungal lectins

It has been proposed that the interactions between several parasitic and pathogenic fungi and their hosts are mediated by soluble lectins present in the fungus. We have cloned and analyzed a gene encoding such a lectin (AOL) from the nematophagous fungus Arthrobotrys oligospora (deuteromycete). The deduced primary structure of the AOL gene displayed an extensive similarity (identity 46.3%) to that of a gene encoding a lectin (ABL) recently isolated from the mushroom Agaricus bisporus (basidiomycete), but not to any other fungal, microbial, plant or animal lectins. The similarities between AOL and ABL were further demonstrated by the observation that an antibody specific for AOL cross-reacted with ABL. Together with data showing that AOL has a binding specificity that is similar to that of ABL [Rosen, S., Bergström, J., Karlsson, K.-A. & Tunlid, A. (1996) Eur. J. Biochem. 238, 830-837], these results indicate that AOL and ABL are members of a novel family of saline soluble lectins present in fungi. Southern blots indicated that there is only one AOL gene in the genome encoding a subunit (monomer) of the lectin. The primary structure of AOL did not show the presence of a typical N-terminal signal sequence. Comparison of the deduced primary structure with the molecular mass of AOL as determined by electrospray mass spectrometry (16153 Da), indicated that AOL has an acetylated N-terminal but no other post-translational modifications, and that a minor isoform is formed by deamidation. Circular dichroism (CD) spectroscopy suggested that the secondary structure of AOL contains 34% beta-sheets, 21% alpha-helix, and 45% turns and coils.

A wound- and methyl jasmonate-inducible transcript coding for a myrosinase-associated protein with similarities to an early nodulin

Myrosinase is regarded as a defense-related enzyme in the Brassicaceae and is capable of hydrolyzing glucosinolates into various compounds, some of which are toxic. Several myrosinase isoenzymes exist, and some of them have been found in association with nonmyrosinase proteins. One of these associated proteins, myrosinase-associated protein (MyAP), was purified from seeds of Brassica napus both in complexes with myrosinase and in a free form. MyAP is a glycosylated, 40-kD protein with at least one intramolecular disufide bridge. A monoclonal anti-MyAP antibody precipitated myrosinase activity from B. napus seed extracts and in these complexes both a 65- and a 70-kD myrosinase were present. The subsequent cloning and analysis revealed the existence of a gene family encoding MyAP or MyAP-related protein and that transcripts corresponding to MyAP in nonwounded plants are found predominantly in seeds. At least some members of the gene family exhibited responsiveness toward wounding and methyl jasmonate vapor. MyAP displayed considerable similarity to an early nodulin (ENOD8) from Medicago sativa and to a proline-rich protein (APG), described as another specific, from Arabidopsis thaliana and B. napus. Similarity to expressed sequence tags from both A. thaliana and Oryza sativa has also been found.

Disruption of an overlapping E-box/ABRE motif abolished high transcription of the napA storage-protein promoter in transgenic Brassica napus seeds

The storage protein napin is one of the major protein components of Brassica napus L. (oilseed rape) seeds. To investigate the transcriptional regulation of the napin promoter, different constructs of the napin gene napA promoter were fused to the Escherichia coli uidA gene and transformed into B. napus. A-152-bp promoter construct directed a strong expression of the marker gene in mature seeds. The 5' deletion of an additional 8 completely abolished this activity. This deletion disrupted sequence motifs that are similar to an E-box, (CA decreases NNTG) and an ABRE (CGCCA decreases CGTGTCC) element (identify is indicated by bold face). Further, internal deletion of a segment corresponding to -133 to -121 caused an eightfold reduction in the activity of the -152 construct. This region contains an element, CAAACAC, conserved in many storage-protein gene promoters. These results imply that the E-box/ABRE-like sequence is a major motif of the napA promoter and suggest that the CAAACAC sequence is important for high activity of the napA promoter. Similar results have been obtained by analysing some of the constructs in transgenic tobacco, suggesting that many of the cis-elements in the napA promoter are conserved, at least in dicotyledonous species.

Evolutionary relationship between human major histocompatibility complex HLA-DR haplotypes

HLA-DR haplotypes of the human major histocompatibility complex are organized in five different groups. They can be identified based on the serological specificity expressed by the polymorphic DRB1 locus and by the presence of a characteristic set of DRB genes. The nucleotide sequences of introns 4 and 5 of the two DRB genes (DRB1(*)01 and DRB6(*)01 ) from a DR1 haplotype and the three DRB genes (DRB1(*)15, DRB6(*)15 , and DRB5(*)15 ), from a DR51 haplotype were determined. This study identified endogenous retroviral long terminal repeat elements (ERV9 LTR) located at identical positions in intron 5 of the DRB1 genes in both the DR1 and DR51 haplotypes. Phylogenetic analyses revealed a close evolutionary relationship between these two haplotypes. The DRB5 gene, unique for the DR51 haplotype, may have been lost by a recent gene deletion event creating the DR1 haplotype. A model for the evolution of the human DR haplotypes involving separate duplication and contraction events is presented.

Processing in vitro of pronapin, the 2S storage-protein precursor of Brassica napus produced in a baculovirus expression system

The maturation of the 2S albumin, napin, in Brassica napus L. involves removal of an amino-terminal and an internal propeptide. Pulse-chase experiments with B. napus embryos showed that intermediates are detectable during the pronapin processing. Intact pronapin was expressed by baculovirus in Spodoptera frugiperda insect cells in order to obtain substrate for studying the processing event. Processing of pronapin with a crude B. napus embryo protein extract resulted in several fragments of similar sizes to those of napin heavy and light chains. The character of the major processing activity in the B. napus extract suggested that it was due to an aspartic proteinase. A secondary activity indicated an additional endoproteinase involved in the pronapin processing. Limited proteolysis of pronapin with a purified aspartic proteinase from Hordeum vulgare showed that cleavage occurred exclusively in the prosequences. The cleavage products formed in-vitro requires additional trimming of the propeptides in order to obtain the subunits of mature napin.

The loop region around amino acid residue 50, the N-terminal part of the alpha-helix, and the C-terminus of human retinol-binding protein are not located in or close to the transthyretin binding site

Although the three-dimensional structures of both human retinol-binding protein (RBP) and transthyretin (TTR) are known, the binding sites have not been defined. In this study we have epitope-mapped a rabbit antiserum against human RBP using synthetic peptides corresponding to all potentially antigenic sites. Immunoreactivity was seen with peptides corresponding to amino acid residues 46-54, 137-146, 143-153, and 172-182 of RBP. Since previous studies have demonstrated that these antibodies bind equally well to free RBP and to the RBP-TTR complex, we conclude that neither the loop region around amino acid residue 50, the N-terminal part of the alpha-helix, nor the C-terminus of RBP is located in or close to the TTR binding site. Our results support the hypothesis that one of the entrance loops is involved in the TTR binding.

Hyperparathyroidism of multiple endocrine neoplasia type 1: candidate gene and parathyroid calcium sensing protein expression

BACKGROUND

Hyperparathyroidism affects most patients with multiple endocrine neoplasia type 1 (MEN 1). This study investigates expression of the candidate MEN1 gene phospholipase C beta 3 (PLC beta 3) and expression and function of a putative calcium sensing protein (CAS) in hyperparathyroidism of MEN 1.

METHODS

In 31 parathyroid glands from 17 patients with MEN 1, CAS distribution was studied immunohistochemically and parallel sections were explored for PLC beta 3 mRNA expression by in situ hybridization. Enzymatically dispersed parathyroid cells were analyzed for cytoplasmic calcium concentrations [Ca2+]i and parathyroid hormone (PTH) release.

RESULTS

All glands exhibited a heterogeneously reduced CAS immunoreactivity, especially meager in nodularly assembled parathyroid cells. Calcium regulated [Ca2+]i and PTH release tended to be more deranged in the glands possessing the lowest immunostaining. Parathyroid PLC beta 3 invariably was homogeneously expressed, and this included even MEN 1 patients with reduced PLC beta 3 expression in endocrine pancreatic tumors.

CONCLUSIONS

The findings support variable calcium insensitivity of [Ca2+]i and PTH release in hyperparathyroidism of MEN 1, apparently coupled to heterogeneously reduced CAS expression. For clarification of the role of PLC beta 3 in MEN 1 parathyroid tumorigenesis further study of this protein is required.

Tissue specific basal expression of soluble murine epoxide hydrolase and effects of clofibrate on the mRNA levels in extrahepatic tissues and liver

The soluble epoxide hydrolase mRNA level in liver was increased eight-fold upon administration of the hypolipidemic drug and peroxisome proliferator clofibrate for 7 days to mice. The soluble epoxide hydrolase mRNA was back at control levels within 1-2 days after clofibrate withdrawal. The highest expression was in liver, intestine and kidney. Lower levels were found in heart and muscle and very low levels were found in testes, lung, brain and spleen. The mRNA levels were increased in liver, kidney and heart by clofibrate.

The unusual 5' splicing border GC is used in myrosinase genes of the Brassicaceae

Myrosinase (thioglucosidase glucohydrolase; EC 3.2.3.1) is a group of isoenzymes in the Brassicaceae, which hydrolyze glucosinolates. Genes encoding myrosinase contain 12 exons and 11 introns. Sequence comparison of two myrosinase genes from Arabidopsis thaliana, TGG1 and TGG2, with the corresponding cDNA from leaves, showed preferential use of a GC dinucleotide as the 5' splicing border in intron 1 instead of an adjacent GT dinucleotide four bp further 3'. This 5' GC splice site is conserved in all seven myrosinase genes characterized from three different species. Likewise, in the 3' region of intron 1 two AG dinucleotides are located seven bp apart. Only the most 5' of these dinucleotides was found to be used in splicing. Sequence analyses of TGG1 cDNA isolated from seeds, siliques and vegetative tissue using reverse transcription PCR showed that the splicing pattern of this intron is identical in these tissues for TGG1. The GT and the most 3' AG dinucleotides mentioned above have been assumed to be the intron borders of intron 1 in several myrosinase genes. The present investigation shows that this assumption is not correct.

Expression of a zeatin-O-glucoside-degrading beta-glucosidase in Brassica napus

A beta-glucosidase was purified from seeds of Brassica napus L. (oilseed rape). The 130-kD native enzyme consisted of a disulfide-linked dimer of 64-kD monomers. Internal amino acid sequences were used to construct degenerate primers for polymerase chain reaction-mediated cloning of cDNA for the enzyme. One nearly full-length and one partial beta-glucosidase-encoding cDNA clone were isolated and sequenced. Southern hybridization showed that beta-glucosidase is encoded by a small gene family in B. napus. Northern hybridization showed that the genes are expressed in the seed, with a low degree of expression in other tissues. In the seed, the expression started at 30 days after pollination (DAP), with the highest expression at 40 DAP. The size of the transcript was approximately 1900 nucleotides. In situ hybridization to developing seeds of B. napus showed that the beta-glucosidase expression started at 30 DAP around the provascular tissue in the embryo axis. In the cotyledons, mRNA initially accumulated around the provascular tissues but was detected first at 35 DAP. At 40 DAP, expression occurred in most parts of the seed. In situ hybridization also detected beta-glucosidase mRNA in shoots, young roots, and the basal part of the hypocotyls. Zeatin-O-glucoside was identified as a natural substrate for B. napus beta-glucosidase.

Epitope mapping of a monoclonal antibody that blocks the binding of retinol-binding protein to its receptor

To define the receptor binding site of retinol-binding protein (RBP) we have generated monoclonal antibodies (mAbs) to human RBP and examined their ability to interfere with the receptor binding. MAbs to two conserved regions efficiently blocked the binding. No major conformational changes in the protein occurred upon mAb binding, since the mAbs could co-immunoprecipitate the RBP-transthyretin (TTR) complex. One blocking mAb showed reactivity to a synthetic peptide corresponding to one entrance loop of the retinol-binding pocket (amino acid residues 60-70). Thus, our results show that at least one of the entrance loops of the barrel of RBP is located in or close to the receptor binding site. It can also be concluded that the receptor and TTR binding sites involve different regions of RBP.

The myrosinase gene family in Arabidopsis thaliana: gene organization, expression and evolution

Myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1.) is in Brassicaceae species such as Brassica napus and Sinapis alba encoded by two differentially expressed gene families, MA and MB, consisting of about 4 and 10 genes, respectively. Southern blot analysis showed that Arabidopsis thaliana contains three myrosinase genes. These genes were isolated from a genomic library and two of them, TGG1 and TGG2, were sequenced. They were found to be located in an inverted mode with their 3' ends 4.4 kb apart. Their organization was highly conserved with 12 exons and 11 short introns. Comparison of nucleotide sequences of TGG1 and TGG2 exons revealed an overall 75% similarity. In contrast, the overall nucleotide sequence similarity in introns was only 42%. In intron 1 the unusual 5' splice border GC was used. Phylogenetic analyses using both distance matrix and parsimony programs suggested that the Arabidopsis genes could not be grouped with either MA or MB genes. Consequently, these two gene families arose only after Arabidopsis had diverged from the other Brassicaceae species. In situ hybridization experiments showed that TGG1 and TGG2 expressing cells are present in leaf, sepal, petal, and gynoecium. In developing seeds, a few cells reacting with the TGG1 probe, but not with the TGG2 probe, were found indicating a partly different expression of these genes.

Characterization of a new myrosinase in Brassica napus

A full-length cDNA clone defining the new myrosinase gene family MC in Brassica napus was isolated and sequenced. Southern hybridization showed that the MC family probably consists of 3 or 4 genes in B. napus. MC genes are expressed in the developing seed, but not in the vegetative tissues investigated. In situ hybridizations to developing seeds showed that the MC genes are expressed in the myrosin cells of the embryo axis and the cotyledons. Complexes with myrosinase and myrosinase-binding protein (MBP) were purified and characterized. Sequencing of peptides from myrosinases occurring in the complexes showed that the 70 kDa myrosinase is encoded by the MC genes, whereas the 65 kDa myrosinase is encoded by the MB genes. This is in contrast to the 75 kDa myrosinase which occurs in free form and is encoded by the MA genes. Deglycosylations of the myrosinase complexes and the free myrosinase showed that the molecular sizes of the myrosinases could be reduced significantly by this treatment, and that the size differences between the different myrosinases are mainly due to differences in glycosylation.

Characterization of three separated exons in the HLA class II DR region of the human major histocompatibility complex

The human major histocompatibility complex, HLA, is a highly polymorphic gene region which includes the DRA and DRB genes. The number of DRB genes differs between haplotypes. The DR4 haplotype seems to be one of the most complex with five DRB loci, DRB1, DRB4, DRB7, DRB8, and DRB9, in addition to the single DRA locus. We determined the nucleotide sequences of three separated DRB exons located between the DRB4 locus and the DRA locus in the DR4 haplotype, two DRB signal-peptide exons (S1 and S3) and one DRB first-domain exon (locus designation DRB9). Sequence comparisons suggest the following order of events for the origin of these exons: DRB9 seems to be the oldest exon and has previously been detected in multiple HLA haplotypes. DRB9 is more divergent than the three other known DRB pseudogenes, all of which have been found in apes. This suggests that DRB9 arose prior to the hominoid divergence. An L1 repeat has been inserted 3' to DRB9. Subsequently, a LTR of the ERV9 retrovirus-like family was inserted into the L1 repeat. Such LTRs have recently been observed in some of the other DRB genes. The pseudogenes DRB7 and DRB8 (containing only exons 3-6) arose after DRB9. Finally, the separated signal peptide exons S1 and S3 were formed. The molecular characterization of these separated DRB exons and insertion elements further clarifies the complex evolutionary history of the HLA-DR region. These selectively neutral exons may serve as useful markers for tracing the phylogeny of HLA haplotypes.

Processing of the 2S storage protein pronapin in Brassica napus and in transformed tobacco

The 2S protein napin in Brassica napus is synthesized as a proprotein from which an N-terminal an an internal propeptide are removed. In order to investigate the mechanism of 2S storage-protein processing, N-terminal sequences were determined for the light and heavy chains of all major napin isoforms isolated. Mutants of a napin gene, with deletions of different portions of the propeptides, were transformed into tobacco and napin protein was isolated. Napin light and heavy chains were separated and their N-terminal amino acid sequences determined. Further, the C-terminal residues of one napin isoform isolated from B. napus and one mutant napin isolated from tobacco were deduced from molecular-mass determinations of the constituents chains. Analyses suggested that the two propeptides are exposed at the surface of the proprotein. The light chain is processed to the correct length independent of the amino acid sequence in the N-terminal propeptide and the processing site. The internal propeptide is attacked by endoproteases. Aminopeptidases and carboxypeptidases then digest portions of the propeptide to the extent allowed by the primary and the three-dimensional structures, often resulting in 2S protein chains with partly frayed ends.