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1.
CD40, a member of the tumour necrosis factor‐α receptor family, is constitutively expressed by cells of haematopoietic and non‐haematopoietic origin, including fibroblasts. Signalling through this receptor molecule regulates inflammatory mediator secretion by many cell types. The work has been performed in healthy subjects and the authors studied, by cellular culture, flow cytometric analysis and ELISA assay, the expression of CD40 and PGE2 (prostaglandin E2) generation on gingival fibroblasts stimulated by β‐AR (β‐adrenoceptor) agonists. Herein, the authors demonstrate that β‐AR subtype activation via their own specific agonists markedly increased CD40 expression on human gingival fibroblasts. This effect was prevented by β‐AR subtype‐specific antagonists. In addition, gingival fibroblast β‐AR stimulation resulted in an increase in PGE2 generation. The inhibition of PLA2 (phospholipase A2) and COX‐1 (cyclo‐oxygenase‐1) but not COX‐2 impaired β‐AR increase of PGE2, an effect that was restored by the addition of low concentrations of PGE2, suggesting that PGE2 generation is implicated in the mechanism underlying β‐AR‐agonist‐mediated CD40 overexpression. Our work has revealed an endogenous β‐AR mediator network involving gingival fibroblasts.  相似文献   

2.
Acetyl‐11‐keto‐β‐boswellic acid (AKBA), an active triterpenoid compound from the extract of Boswellia serrate, has been reported previously in our group to alleviate fibrosis in vascular remodelling. This study aimed to elucidate the in vivo and in vitro efficacy and mechanism of AKBA in renal interstitial fibrosis. The experimental renal fibrosis was produced in C57BL/6 mice via unilateral ureteral obstruction (UUO). Hypoxia‐induced HK‐2 cells were used to imitate the pathological process of renal fibrosis in vitro. Results showed that the treatment of AKBA significantly alleviated UUO‐induced impairment of renal function and improved the renal fibrosis by decreasing the expression of TGF‐β1, α‐SMA, collagen I and collagen IV in UUO kidneys. In hypoxia‐induced HK‐2 cells, AKBA displayed remarkable cell protective effects and anti‐fibrotic properties by increasing the cell viability, decreasing the lactate dehydrogenase (LDH) release and inhibiting fibrotic factor expression. Moreover, in obstructed kidneys and HK‐2 cells, AKBA markedly down‐regulated the expression of TGFβ‐RI, TGFβ‐RII, phosphorylated‐Smad2/3 (p‐Smad2/3) and Smad4 in a dose‐dependent fashion while up‐regulated the expression of Klotho and Smad7 in the same manner. In addition, the effects of AKBA on the Klotho/TGF‐β/Smad signalling were reversed by transfecting with siRNA‐Klotho in HK‐2 cells. In conclusion, our findings provide evidence that AKBA can effectively protect kidney against interstitial fibrosis, and this renoprotective effect involves the Klotho/TGF‐β/Smad signalling pathway. Therefore, AKBA could be considered as a promising candidate drug for renal interstitial fibrosis.  相似文献   

3.
Plant cell cultures constitute eco‐friendly biotechnological platforms for the production of plant secondary metabolites with pharmacological activities, as well as a suitable system for extending our knowledge of secondary metabolism. Despite the high added value of taxol and the importance of taxanes as anticancer compounds, several aspects of their biosynthesis remain unknown. In this work, a genomewide expression analysis of jasmonate‐elicited Taxus baccata cell cultures by complementary DNA‐amplified fragment length polymorphism (cDNA‐AFLP) indicated a correlation between an extensive elicitor‐induced genetic reprogramming and increased taxane production in the targeted cultures. Subsequent in silico analysis allowed us to identify 15 genes with a jasmonate‐induced differential expression as putative candidates for genes encoding enzymes involved in five unknown steps of taxane biosynthesis. Among them, the TB768 gene showed a strong homology, including a very similar predicted 3D structure, with other genes previously reported to encode acyl‐CoA ligases, thus suggesting a role in the formation of the taxol lateral chain. Functional analysis confirmed that the TB768 gene encodes an acyl‐CoA ligase that localizes to the cytoplasm and is able to convert β‐phenylalanine, as well as coumaric acid, into their respective derivative CoA esters. β‐phenylalanyl‐CoA is attached to baccatin III in one of the last steps of the taxol biosynthetic pathway. The identification of this gene will contribute to the establishment of sustainable taxol production systems through metabolic engineering or synthetic biology approaches.  相似文献   

4.
Gamma‐aminobutyric acid type A receptors (GABAARs) are the most important inhibitory chloride ion channels in the central nervous system and are major targets for a wide variety of drugs. The subunit compositions of GABAARs determine their function and pharmacological profile. GABAARs are heteropentamers of subunits, and (α1)2(β3)2(γ2L)1 is a common subtype. Biochemical and biophysical studies of GABAARs require larger quantities of receptors of defined subunit composition than are currently available. We previously reported high‐level production of active human α1β3 GABAAR using tetracycline‐inducible stable HEK293 cells. Here we extend the strategy to receptors containing three different subunits. We constructed a stable tetracycline‐inducible HEK293‐TetR cell line expressing human (N)–FLAG–α1β3γ2L–(C)–(GGS)3GK–1D4 GABAAR. These cells achieved expression levels of 70–90 pmol [3H]muscimol binding sites/15‐cm plate at a specific activity of 15–30 pmol/mg of membrane protein. Incorporation of the γ2 subunit was confirmed by the ratio of [3H]flunitrazepam to [3H]muscimol binding sites and sensitivity of GABA‐induced currents to benzodiazepines and zinc. The α1β3γ2L GABAARs were solubilized in dodecyl‐d ‐maltoside, purified by anti‐FLAG affinity chromatography and reconstituted in CHAPS/asolectin at an overall yield of ~30%. Typical purifications yielded 1.0–1.5 nmoles of [3H]muscimol binding sites/60 plates. Receptors with similar properties could be purified by 1D4 affinity chromatography with lower overall yield. The composition of the purified, reconstituted receptors was confirmed by ligand binding, Western blot, and proteomics. Allosteric interactions between etomidate and [3H]muscimol binding were maintained in the purified state.  相似文献   

5.
Ashbya gossypii has been recently considered as a host for the expression of recombinant proteins. The production levels achieved thus far were similar to those obtained with Saccharomyces cerevisiae for the same proteins. Here, the β‐galactosidase from Aspergillus niger was successfully expressed and secreted by A. gossypii from 2‐µm plasmids carrying the native signal sequence at higher levels than those secreted by S. cerevisiae laboratorial strains. Four different constitutive promoters were used to regulate the expression of β‐galactosidase: A. gossypii AgTEF and AgGPD promoters, and S. cerevisiae ScADH1 and ScPGK1 promoters. The native AgTEF promoter drove the highest expression levels of recombinant β‐galactosidase in A. gossypii, leading to 2‐ and 8‐fold higher extracellular activity than the AgGPD promoter and the heterologous promoters, respectively. In similar production conditions, the levels of active β‐galactosidase secreted by A. gossypii were up to 37 times higher than those secreted by recombinant S. cerevisiae and ~2.5 times higher than those previously reported for the β‐galactosidase‐high producing S. cerevisiae NCYC869‐A3/pVK1.1. The substitution of glucose by glycerol in the production medium led to a 1.5‐fold increase in the secretion of active β‐galactosidase by A. gossypii. Recombinant β‐galactosidase secreted by A. gossypii was extensively glycosylated, as are the native A. niger β‐galactosidase and recombinant β‐galactosidase produced by yeast. These results highlight the potential of A. gossypii as a recombinant protein producer and open new perspectives to further optimize recombinant protein secretion in this fungus. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:261–268, 2014  相似文献   

6.
Objective: Acetyl CoA carboxylase (ACC) is a key enzyme in energy balance. It controls the synthesis of malonyl‐CoA, an allosteric inhibitor of carnitine palmitoyltransferase‐1 (CPT‐I). CPT‐I is the gatekeeper of free fatty acid (FFA) oxidation. To test the hypothesis that both enzymes play critical roles in regulation of FFA partitioning in adipocytes, we compared enzyme mRNA expression and specific activity from fed, fasted, and diabetic rats. Research Methods and Procedures: Direct effects of nutritional state, insulin, and FFAs on CPT‐I and ACC mRNA expression were assessed in adipocytes, liver, and cultured adipose tissue explants. We also determined FFA partitioning in adipocytes from donors exposed to different nutritional conditions. Results: CPT‐I mRNA and activity decreased in adipocytes but increased in liver in response to fasting. ACC mRNA and activity decreased in both adipocytes and liver during fasting. These changes were not caused directly by fasting‐associated changes in plasma insulin and FFA concentrations because insulin suppressed CPT‐I mRNA and did not affect ACC mRNA in vitro, whereas exogenous oleate had no effect on either. Despite the decrease in adipocyte CPT‐I mRNA and specific activity, CO2 production from endogenous FFAs increased, suggesting increased FFA transport through CPT‐I for β‐oxidation. Discussion: Stimulation of FFA transport through CPT‐I occurs in both tissues, but CPT‐I mRNA and specific activity correlate with FFA transport in liver and not in adipocytes. We conclude that the mechanism responsible for increasing FFA oxidation in adipose tissue during fasting involves mainly allosteric regulation, whereas altered gene expression may play a central role in the liver.  相似文献   

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9.
Peroxisomes are thought to have played a key role in the evolution of metabolic networks of photosynthetic organisms by connecting oxidative and biosynthetic routes operating in different compartments. While the various oxidative pathways operating in the peroxisomes of higher plants are fairly well characterized, the reactions present in the primitive peroxisomes (microbodies) of algae are poorly understood. Screening of a Chlamydomonas insertional mutant library identified a strain strongly impaired in oil remobilization and defective in Cre05.g232002 (CrACX2), a gene encoding a member of the acyl‐CoA oxidase/dehydrogenase superfamily. The purified recombinant CrACX2 expressed in Escherichia coli catalyzed the oxidation of fatty acyl‐CoAs into trans‐2‐enoyl‐CoA and produced H2O2. This result demonstrated that CrACX2 is a genuine acyl‐CoA oxidase, which is responsible for the first step of the peroxisomal fatty acid (FA) β‐oxidation spiral. A fluorescent protein‐tagging study pointed to a peroxisomal location of CrACX2. The importance of peroxisomal FA β‐oxidation in algal physiology was shown by the impact of the mutation on FA turnover during day/night cycles. Moreover, under nitrogen depletion the mutant accumulated 20% more oil than the wild type, illustrating the potential of β‐oxidation mutants for algal biotechnology. This study provides experimental evidence that a plant‐type FA β‐oxidation involving H2O2‐producing acyl‐CoA oxidation activity has already evolved in the microbodies of the unicellular green alga Chlamydomonas reinhardtii.  相似文献   

10.
Engineering the production of polyhydroxyalkanoates (PHAs) into high biomass bioenergy crops has the potential to provide a sustainable supply of bioplastics and energy from a single plant feedstock. One of the major challenges in engineering C4 plants for the production of poly[(R)‐3‐hydroxybutyrate] (PHB) is the significantly lower level of polymer produced in the chloroplasts of mesophyll (M) cells compared to bundle sheath (BS) cells, thereby limiting the full PHB yield‐potential of the plant. In this study, we provide evidence that the access to substrate for PHB synthesis may limit polymer production in M chloroplasts. Production of PHB in M cells of sugarcane is significantly increased by replacing β‐ketothiolase, the first enzyme in the bacterial PHA pathway, with acetoacetyl‐CoA synthase. This novel pathway enabled the production of PHB reaching an average of 6.3% of the dry weight of total leaf biomass, with levels ranging from 3.6 to 11.8% of the dry weight (DW) of individual leaves. These yields are more than twice the level reported in PHB‐producing sugarcane containing the β‐ketothiolase and illustrate the importance of producing polymer in mesophyll plastids to maximize yield. The molecular weight of the polymer produced was greater than 2 × 106 Da. These results are a major step forward in engineering a high biomass C4 grass for the commercial production of PHB.  相似文献   

11.
Tuberculosis is still affecting millions of people worldwide, and new resistant strains of Mycobacterium tuberculosis are being found. It is therefore necessary to find new compounds for treatment. In this paper, we report the synthesis and in vitro testing of peptidyl β‐aminoboronic acids and β‐aminoboronates with anti‐tubercular activity. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

12.
5α‐Androst‐16‐en‐3α‐ol (α‐androstenol) is an important contributor to human axilla sweat odor. It is assumed that α‐andostenol is excreted from the apocrine glands via a H2O‐soluble conjugate, and this precursor was formally characterized in this study for the first time in human sweat. The possible H2O‐soluble precursors, sulfate and glucuronide derivatives, were synthesized as analytical standards, i.e., α‐androstenol, β‐androstenol sulfates, 5α‐androsta‐5,16‐dien‐3β‐ol (β‐androstadienol) sulfate, α‐androstenol β‐glucuronide, α‐androstenol α‐glucuronide, β‐androstadienol β‐glucuronide, and α‐androstenol β‐glucuronide furanose. The occurrence of α‐androstenol β‐glucuronide was established by ultra performance liquid chromatography (UPLC)/MS (heated electrospray ionization (HESI)) in negative‐ion mode in pooled human sweat, containing eccrine and apocrine secretions and collected from 25 female and 24 male underarms. Its concentration was of 79 ng/ml in female secretions and 241 ng/ml in male secretions. The release of α‐androstenol was observed after incubation of the sterile human sweat or α‐androstenol β‐glucuronide with a commercial glucuronidase enzyme, the urine‐isolated bacteria Streptococcus agalactiae, and the skin bacteria Staphylococcus warneri DSM 20316, Staphylococcus haemolyticus DSM 20263, and Propionibacterium acnes ATCC 6919, reported to have β‐glucuronidase activities. We demonstrated that if α‐ and β‐androstenols and androstadienol sulfates were present in human sweat, their concentrations would be too low to be considered as potential precursors of malodors; therefore, the H2O‐soluble precursor of α‐androstenol in apocrine secretion should be a β‐glucuronide.  相似文献   

13.
To develop a long cycle life and good rate capability electrode, 3D hierarchical porous α‐Fe2O3 nanosheets are fabricated on copper foil and directly used as binder‐free anode for lithium‐ion batteries. This electrode exhibits a high reversible capacity and excellent rate capability. A reversible capacity up to 877.7 mAh g?1 is maintained at 2 C (2.01 A g?1) after 1000 cycles, and even when the current is increased to 20 C (20.1 A g?1), a capacity of 433 mA h g?1 is retained. The unique porous 3D hierarchical nanostructure improves electronic–ionic transport, mitigates the internal mechanical stress induced by the volume variations of the electrode upon cycling, and forms a 3D conductive network during cycling. No addition of any electrochemically inactive conductive agents or polymer binders is required. Therefore, binder‐free electrodes further avoid the uneven distribution of conductive carbon on the current collector due to physical mixing and the addition of an insulator (binder), which has benefits leading to outstanding electrochemical performance.  相似文献   

14.
A promising means of rapid screening of extended‐spectrum‐β‐lactamase (ESBL), AmpC β‐lactamase, and co‐production of ESBL and AmpC that combines resazurin chromogenic agar (RCA) with a combined disc method is here reported. Cefpodoxime (CPD) discs with and without clavulanic acid (CA), cloxacillin (CX) and CA+CX were evaluated against 86 molecularly confirmed β‐lactamase‐producing Enterobacteriaceae , including 15 ESBLs, 32 AmpCs, nine co‐producers of ESBL and AmpC and 30 carbapenemase producers. The CA and CX synergy test successfully detected all ESBL producers (100% sensitivity and 98.6% specificity) and all AmpC producers (100% sensitivity and 96.36% specificity). This assay also performed well in screening for co‐existence of ESBL and AmpC (88.89% sensitivity and 100% specificity). The RCA assay is simple and inexpensive and provides results within 7 hr. It can be performed in any microbiological laboratory, in particular, in geographic regions in which ESBL, AmpC or co‐β‐lactamase‐producing Enterobacteriaceae are endemic.
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15.
β‐dystroglycan (β‐DG) is a widely expressed transmembrane protein that plays important roles in connecting the extracellular matrix to the cytoskeleton, and thereby contributing to plasma membrane integrity and signal transduction. We previously observed nuclear localization of β‐DG in cultured cell lines, implying the existence of a nuclear targeting mechanism that directs it to the nucleus instead of the plasma membrane. In this study, we delineate the nuclear import pathway of β‐DG, characterizing a functional nuclear localization signal (NLS) in the β‐DG cytoplasmic domain, within amino acids 776–782. The NLS either alone or in the context of the whole β‐DG protein was able to target the heterologous GFP protein to the nucleus, with site‐directed mutagenesis indicating that amino acids R779 and K780 are critical for NLS functionality. The nuclear transport molecules Importin (Imp)α and Impβ bound with high affinity to the NLS of β‐DG and were found to be essential for NLS‐dependent nuclear import in an in vitro reconstituted nuclear transport assay; cotransfection experiments confirmed the dependence on Ran for nuclear accumulation. Intriguingly, experiments suggested that tyrosine phosphorylation of β‐DG may result in cytoplasmic retention, with Y892 playing a key role. β‐DG thus follows a conventional Impα/β‐dependent nuclear import pathway, with important implications for its potential function in the nucleus. J. Cell. Biochem. 110: 706–717, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

16.
Central (hypothalamic) control of bone mass is proposed to be mediated through β2‐adrenergic receptors (β2‐ARs). While investigations in mouse bone cells suggest that epinephrine enhances both RANKL and OPG mRNA via both β‐ARs and α‐ARs, whether α‐ARs are expressed in human bone cells is controversial. The current study investigated the expression of α1‐AR and β2‐AR mRNA and protein and the functional role of adrenergic stimulation in human osteoblasts (HOBs). Expression of α1B‐ and β2‐ARs was examined by RT‐PCR, immunofluorescence microscopy and Western blot (for α1B‐ARs). Proliferation in HOBs was assessed by 3H‐thymidine incorporation and expression of RANKL and OPG was determined by quantitative RT‐PCR. RNA message for α1B‐ and β2‐ARs was expressed in HOBs and MG63 human osteosarcoma cells. α1B‐ and β2‐AR immunofluorescent localization in HOBs was shown for the first time by deconvolution microscopy. α1B‐AR protein was identified in HOBs by Western blot. Both α1‐agonists and propranolol (β‐blocker) increased HOB replication but fenoterol, a β2‐agonist, inhibited it. Fenoterol nearly doubled RANKL mRNA and this was inhibited by propranolol. The α1‐agonist cirazoline increased OPG mRNA and this increase was abolished by siRNA knockdown of α1B‐ARs in HOBs. These data indicate that both α1‐ARs and β2‐ARs are present and functional in HOBs. In addition to β2‐ARs, α1‐ARs in human bone cells may play a role in modulation of bone turnover by the sympathetic nervous system. J. Cell. Physiol. 220: 267–275, 2009. © 2009 Wiley‐Liss, Inc.  相似文献   

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18.
GABAA receptors are pentameric ligand‐gated ion channels that mediate inhibitory fast synaptic transmission in the central nervous system. Consistent with recent pentameric ligand‐gated ion channels structures, sequence analysis predicts an α‐helix near the N‐terminus of each GABAA receptor subunit. Preceding each α‐helix are 8–36 additional residues, which we term the N‐terminal extension. In homomeric GABAC receptors and nicotinic acetylcholine receptors, the N‐terminal α‐helix is functionally essential. Here, we determined the role of the N‐terminal extension and putative α‐helix in heteromeric α1β2γ2 GABAA receptors. This role was most prominent in the α1 subunit, with deletion of the N‐terminal extension or further deletion of the putative α‐helix both dramatically reduced the number of functional receptors at the cell surface. Conversely, deletion of the β2 or γ2 N‐terminal extension had little effect on the number of functional cell surface receptors. Additional deletion of the putative α‐helix in the β2 or γ2 subunits did, however, decrease both functional cell surface receptors and incorporation of the γ2 subunit into mature receptors. In the β2 subunit only, α‐helix deletions affected GABA sensitivity and desensitization. Our findings demonstrate that N‐terminal extensions and α‐helices make key subunit‐specific contributions to assembly, consistent with both regions being involved in inter‐subunit interactions.

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19.
Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation and abnormal inflammatory response. Wnt/β‐catenin and AMP‐activated protein kinase (AMPK) have been shown to modulate lung inflammatory responses and injury. However, it remains elusive whether Wnt/β‐catenin and AMPK modulate nuclear factor erythroid‐2 related factor‐2 (Nrf2)‐mediated protective responses during the development of emphysema. Here we showed that treatment with a Wnt pathway activator (LiCl) reduced elastase‐induced airspace enlargement and cigarette smoke extract (CSE)‐induced lung inflammatory responses in WT mice, which was associated with increased activation of Nrf2 pathway. Interestingly, these effects of LiCl were not observed in Nrf2?/? mice exposed to elastase. In normal human bronchial epithelial (NHBE) cells, Wnt3a overexpression up‐regulated, whereas Wnt3a knockdown further down‐regulated the levels of Nrf2 and its target proteins heme oxygenase‐1 (HO‐1) and NAD(P)H: quinone oxidoreductase 1 (NQO1) by CSE treatment. In contrast, Nrf2 deficiency did not have any effects on Wnt/β‐catenin pathway in mouse lungs and NHBE cells. Both elastase and CSE exposures reduced AMPK phosphorylation. A specific AMPK activator metformin increased Wnt3a, β‐catenin, Nrf2 phosphorylation and activation but reduced the levels of IL‐6 and IL‐8 in NHBE cells and mouse lungs exposed to CSE. Furthermore, Nrf2 deficiency abolished the protection of metformin against CSE‐induced increase in IL‐6 and IL‐8 in NHBE cells. In conclusion, Nrf2 mediates the protective effects of both Wnt3a/β‐catenin and AMPK on lung inflammatory responses during the development of COPD/emphysema. These findings provide potential therapeutic targets for the intervention of COPD/emphysema.  相似文献   

20.
Metabolic syndrome is marked by perturbed glucocorticoid (GC) signaling, systemic inflammation, and altered immune status. Dehydroepiandrosterone (DHEA), a major circulating adrenal steroid and dietary supplement, demonstrates antiobesity, anti‐inflammatory, GC‐opposing and immune‐modulating activity when administered to rodents. However, plasma DHEA levels failed to correlate with metabolic syndrome and oral replacement therapy provided only mild benefits to patients. Androstene‐3β,7β,17β‐triol (β‐AET) an anti‐inflammatory metabolite of DHEA, also exhibits GC‐opposing and immune‐modulating activity when administered to rodents. We hypothesized a role for β‐AET in obesity. We now report that plasma levels of β‐AET positively correlate with BMI in healthy men and women. Together with previous studies, the observations reported here may suggest a compensatory role for β‐AET in preventing the development of metabolic syndrome. The β‐AET structural core may provide the basis for novel pharmaceuticals to treat this disease.  相似文献   

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