Functional analysis of block 5, one of the highly conserved amino acid sequences in the 130-kDa CryIVA protein produced by Bacillus thuringiensis subsp. israelensis

AbstractThere are five amino acid sequences highly conserved among Bacillus thuringiensis δ-endotoxins. We have changed the amino acid residues in block 5, one of the conserved sequences, of CryIVA. When the amino acid residues with charged side chains were replaced by others, the amount of production of the altered CryIVA protein was markedly decreased. It is suggested that the decrease is caused by the unstable conformation of the altered CryIVA protein molecule, as judged by digestion with trypsin and thermolysin. On the other hand, the substitution of amino acid residues in block 5 did not affect the insecticidal activity of CryIVA. These results strongly suggest that block 5 of CryIVA is one of the stability-determining elements of the protoxin molecule

Molecular mechanisms of the synergy between cysteinyl-leukotrienes and receptor tyrosine kinase growth factors on human bronchial fibroblast proliferation

We have reported that cysteinyl-leukotrienes (cys-LTs) synergise not only with epidermal growth factor (EGF) but also with platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) to induce mitogenesis in human bronchial fibroblasts. We now describe the molecular mechanisms underlying this synergism. Mitogenesis was assessed by incorporation of [3H]thymidine into DNA and changes in protein phosphorylation by Western blotting. Surprisingly, no CysLT receptor antagonists (MK-571, montelukast, BAY u9773) prevented the synergistic mitogenesis. LTD4 did not cause phosphorylation of EGFR nor did it augment EGF-induced phosphorylation of EGFR, and the synergy between LTD4 and EGF was not blocked by the metalloproteinase inhibitor GM6001 or by an HB-EGF neutralising antibody. The EGFR-selective kinase inhibitor, AG1478, suppressed the synergy by LTD4 and EGF, but had no effect on the synergy with PDGF and FGF. While inhibitors of mitogen-activated protein kinase, phosphatidylinositol 3-kinase and protein kinase C (PKC) prevented the synergy, these drugs also inhibited mitogenesis elicited by EGF alone. In contrast, pertussis toxin (PTX) efficiently inhibited the potentiating effect of LTD4 on EGF-induced mitogenesis, as well as that provoked by PDGF or FGF, but had no effect on mitogenesis elicited by the growth factors alone. Whereas LTD4 alone did not augment phosphorylation of extracellular signal-regulated kinase (Erk)-1/2 and Akt, it increased phosphorylation of PKC in a Gi-dependent manner. Addition of LTD4 prolonged the duration of EGF-induced phosphorylation of Erk-1/2 and Akt, both of which were sensitive to PTX. The effect of cys-LTs involves a PTX-sensitive and PKC-mediated intracellular pathway leading to sustained growth factor-dependent phosphorylation of Erk-1/2 and Akt

Efficacy of one time per day, single-inhaler indacaterol/glycopyrronium/mometasone in patients with inadequately controlled asthma: post hoc analysis of IRIDIUM study in Asian population

Background and objective The 52-week IRIDIUM study demonstrated the efficacy of indacaterol acetate/glycopyrronium bromide/mometasone furoate (IND/GLY/MF) versus IND/MF and salmeterol xinafoate/fluticasone propionate (SAL/FLU) in patients with symptomatic asthma, despite long-acting β2-agonist/inhaled corticosteroids (LABA/ICS) medium-dose or high-dose, predicted forced expiratory volume in 1 s (FEV1) <80% and at least one exacerbation in the previous year. Here, we present data from a post hoc analysis of the IRIDIUM study in the Asian subpopulation.Methods This post hoc analysis evaluated improvements in lung function, asthma control and reduction in asthma exacerbations with IND/GLY/MF medium- (150/50/80 µg) and high-dose (150/50/160 µg) versus IND/MF medium- (150/160 µg) and high-dose (150/320 µg), all one time per day and SAL/FLU high-dose (50/500 µg) two times per day, in Asian patients from the IRIDIUM study.Results In total, 258 patients (IND/GLY/MF medium-dose, 52; IND/GLY/MF high-dose, 52; IND/MF medium-dose, 51; IND/MF high-dose, 51; SAL/FLU high-dose, 52) were included. IND/GLY/MF medium- and high-dose showed greater improvement in trough FEV1 at week 26 versus respective doses of IND/MF (Δ, 100 mL and 101 mL; both p<0.05, respectively), and SAL/FLU high-dose (Δ, 125 mL; p=0.0189, and 136 mL; p=0.0118, respectively), which were maintained over 52 weeks. Both doses of IND/GLY/MF showed greater improvement in morning and evening peak expiratory flow versus respective doses of IND/MF and SAL/FLU high-dose at week 52. The changes in Asthma Control Questionnaire-7 scores from baseline were comparable in all treatment groups. IND/GLY/MF medium- and high-dose showed greater reductions in severe (34%, 69%), moderate or severe (18%, 54%) and all exacerbations (21%, 34%) compared with SAL/FLU high-dose over 52 weeks.Conclusion One time per day, single-inhaler IND/GLY/MF improved lung function, reduced asthma exacerbations and provided comparable asthma control versus IND/MF and SAL/FLU in Asian patients with inadequately controlled asthma despite LABA/ICS. The results of this analysis were consistent with the overall population in the IRIDIUM study

Cysteinyl leukotrienes synergize with growth factors to induce proliferation of human bronchial fibroblasts

Background: Cysteinyl leukotrienes (cys-LTs) are potent asthma-related mediators that function through their G protein–coupled receptors, cys-LT receptor type 1 (CysLT1R) and cys-LT receptor type 2 (CysLT2R).Objective: Because many G protein–coupled receptors transactivate the epidermal growth factor receptor (EGFR) through metalloprotease-mediated ligand shedding, we investigated the effects of cys-LTs on signal transduction and proliferation of bronchial fibroblasts.Methods: Human bronchial fibroblasts were grown from biopsy specimens of healthy subjects. Mitogenesis was assessed on the basis of tritiated methylthymidine incorporation.Results: Leukotriene (LT) D4 alone did not increase mitogenesis but dose-dependently increased thymidine incorporation and cell proliferation in the presence of epidermal growth factor (EGF). The enhancement was not prevented by CysLT1R antagonists (MK-571 and montelukast) or by a dual antagonist (BAY u9773), which is consistent with the lack of detectable mRNA for CysLT1R and CysLT2R in bronchial fibroblasts. LTD4 did not cause EGFR transphosphorylation nor was the synergism blocked by the metalloprotease inhibitor GM6001. The EGFR-selective kinase inhibitor AG1478 suppressed the synergy between LTD4 and EGF but had no effect on synergistic interactions of LTD4 with other receptor tyrosine kinase growth factors. The effect of LTD4 involved a pertussis toxin–sensitive and protein kinase C–mediated intracellular pathway, leading to sustained growth factor–dependent phosphorylation of extracellular signal–regulated kinase 1/2 and protein kinase B (PKB/Akt).Conclusion: Cys-LTs do not transactivate EGFR but have a broader capability to synergize with receptor tyrosine kinase pathways.Clinical implications: This study implies a critical role of cys-LTs in airway fibrosis in asthma and other chronic airway diseases, which might not be blocked by therapy with current LT receptor antagonists.Abbreviations: ADAM, A disintegrin and metalloproteinase; bFGF, Basic fibroblast growth factor; cys-LT, Cysteinyl leukotriene; CysLT1R, Cysteinyl leukotriene receptor type 1; CysLT2R, Cysteinyl leukotriene receptor type 2; DMEM, Dulbecco's modified Eagle's medium; EGF, Epidermal growth factor; EGFP, Enhanced green fluorescent protein; EGFR, Epidermal growth factor receptor; Erk, Extracellular signal–regulated kinase; Gi/o, G protein ? inhibitory subunit; GPCR, G protein–coupled receptor; LT, Leukotriene; MAPK, Mitogen-activated protein kinase; OVA, Ovalbumin; PDGF, Platelet-derived growth factor; PKC, Protein kinase C; PTX, Pertussis toxin; RTK, Receptor tyrosine kinase; RT-qPCR, Reverse transcription quantitative PCR; TBST, Tris-buffered saline with 0.1% Tween 20

The genetics of asthma: ADAM33 as an example of a susceptibility gene

The ability to identify novel disease genes by positional cloning led to the identification of a disintegrin and metalloprotease (ADAM)33 gene on chromosome 20p13 as a susceptibility gene for asthma. Case-control and family-based association studies have mostly confirmed a link between ADAM33 and asthma. Its restricted expression to mesenchymal cells as well as its association with bronchial hyperresponsiveness and accelerated decline in lung function over time point strongly to its involvement in the structural airway components of asthma, such as remodeling. Extensive alternative splicing, expression during branching morphogensis in the developing fetus, impaired lung function in childhood, the production of a soluble form linked to chronic asthma, and tight epigenetic regulation indicate a level of complexity in the way ADAM33 influences disease phenotype. Its recent association with chronic obstructive pulmonary disease as well as with asthma and lung development points to functions relating to airway wall modeling and remodeling as a general morphogenetic repair gene rather than being restricted to asthma

Characterization of ciliated bronchial epithelium 1, a ciliated cell-associated gene induced during mucociliary differentiation

Lung epithelial structure is altered in asthma; however, the precise mechanisms underlying epithelial repair, including differentiation from basal to columnar epithelial cells, are not well defined. In the course of random sequencing of a cDNA library from human lung biopsies, we have identified a novel gene, ciliated bronchial epithelium 1 (CBE1). Expression of CBE1 was induced during in vitro differentiation of bronchial epithelial cells. Synchronous expression with tektin and hepatocyte nuclear factor 3/forkhead homologue 4, down-regulation by interleukin-13, and its tissue distribution strongly suggested that CBE1 is associated with ciliated cells. Two isoforms of the 0.7-kb full-length cDNA were identified, resulting in open reading frames with different carboxyl termini, with no homology to known proteins. Expression of CBE1 in ciliated epithelial cells was confirmed by immunohistochemistry. Quantitative reverse transcription–polymerase chain reaction analysis using bronchial biopsies showed no difference of expression of CBE1 between normal subjects and subjects with asthma. Expression studies showed that CBE1 is nuclear- or perinuclear-localized, depending on cell type. Regulated expression during differentiation and the subcellular localization of CBE1 suggest that it may play an important role in the differentiation and/or function of ciliated cells in human airways

The soluble form of a disintegrin and metalloprotease 33 promotes angiogenesis: Implications for airway remodeling in asthma

Background: A disintegrin and metalloprotease (ADAM)–33 is a susceptibility gene for asthma and chronic obstructive pulmonary disease whose function remains unknown.Objective: Because asthmatic bronchoalveolar lavage fluid contains high levels of soluble ADAM33 (sADAM33), which includes the catalytic domain, we postulated that its release from cell membranes might play functional roles in airway remodeling by promoting angiogenesis.Methods: The proangiogenic activity of the highly purified catalytic domain of ADAM33 or a catalytically inactive mutant was studied in vitro (Matrigel assay), ex vivo (human embryonic/fetal lung explants) and in vivo (chorioallantoic membrane assay). The regulation of sADAM33 release from cells overexpressing full-length ADAM33 and its biological activity were characterized.Results: We show that the purified catalytic domain of ADAM33, but not its inactive mutant, causes rapid induction of endothelial cell differentiation in vitro, and neovascularization ex vivo and in vivo. We also show that TGF-?2 enhances sADAM33 release from cells overexpressing full-length ADAM33 and that this truncated form is biologically active.Conclusion: The discovery that sADAM33 promotes angiogenesis defines it as a tissue remodeling gene with potential to affect airflow obstruction and lung function independently of inflammation. As TGF-?2 enhances sADAM33 release, environmental factors that cause epithelial damage may synergize with ADAM33 in asthma pathogenesis, resulting in a disease-related gain of function. This highlights the potential for interplay between genetic and environmental factors in this complex disease