共查询到20条相似文献,搜索用时 15 毫秒
1.
Jizhong Wang Chengli Yang Xing Chen Bingxin Bao Xuan Zhang Dali Li Xingfan Du Ruofu Shi Junfang Yang Ronghui Zhu 《Biotechnology letters》2016,38(8):1315-1320
Objectives
To find an efficient and cheap system for NAD+ regenerationResults
A NADH-ferricyanide dehydrogenase was obtained from an isolate of Escherichia coli. Optimal activity of the NADH dehydrogenase was at 45 °C and pH 7.5, with a K m value for NADH of 10 μM. By combining the NADH dehydrogenase, potassium ferricyanide and laccase, a bi-enzyme system for NAD+ regeneration was established. The system is attractive in that the O2 consumed by laccase is from air and the sole byproduct of the reaction is water. During the reaction process, 10 mM NAD+ was transformed from NADH in less than 2 h under the condition of 0.5 U NADH dehydrogenase, 0.5 U laccase, 0.1 mM potassium ferricyanide at pH 5.6, 30 °CConclusion
The bi-enzyme system employed the NADH-ferricyanide dehydrogenase and laccase as catalysts, and potassium ferricyanide as redox mediator, is a promising alternative for NAD+ regeneration.2.
In cultured A6 monolayers from distal Xenopus kidney, external Ni2+ stimulated active Na+ uptake via the epithelial Na+ channel, ENaC. Transepithelial capacitance measurements ruled out exocytosis of ENaC-containing vesicles underlying the Ni2+ effect. Na+ current noise analysis was performed using the neutral Na+-channel blocker 6-chloro-3,5-diamino-pyrazine-2-carboxamide (CDPC) and amiloride. The analysis of CDPC-induced noise in terms of a three-state channel model revealed that Ni2+ elicits an increase in the number of open channels as well as in the spontaneous open probability. While Ni2+ had no influence on CDPC-blocker kinetics, the macroscopic and microscopic blocking kinetics of amiloride were affected. Ni2+ turned out to compete with amiloride for a putative binding site but not with CDPC. Moreover, external Na+—known to compete with amiloride and so producing the self-inhibition phenomenon—and Ni2+ exerted mutually exclusive analogous effects on amiloride kinetics. Na+ current kinetics revealed that Ni2+ prevents ENaC to be downregulated by self-inhibition. Co2+ behaved similarly to Ni2+, whereas Zn2+ did not. Attempts to disclose the chemical nature of the site reacting with Ni2+ suggested cysteine but not histidine as reaction partner. 相似文献
3.
Gang Tang Yi Shen Pan Gao Shuang-Shuang Song Liang-Yi Si 《In vitro cellular & developmental biology. Animal》2018,54(3):250-256
Cardiac hypertrophy plays a major role in heart failure and is related to patient morbidity and mortality. Calcium overloading is a main risk for cardiac hypertrophy, and Na+/K+-ATPase (NKA) has been found that it could not only regulate intracellular Na+ levels but also control the intracellular Ca2+ ([Ca2+]i) level through Na+/Ca2+-exchanger (NCX). Recent studies have reported that klotho could affect [Ca2+]i level. In this study, we aimed at exploring the role of klotho in improving isoproterenol-induced hypertrophic response of H9C2 cells. The H9C2 cells were randomly divided into control and isoproterenol (ISO) (10 μM) groups. Klotho protein (10 μg/ml) or NKAα2 siRNA was used to determine the changes in isoproterenol-induced hypertrophic response. The alterations of [Ca2+]i level were measured by spectrofluorometry. Our results showed that H9C2 cells which were treated with isoproterenol presented a higher level of [Ca2+]i and hypertrophic gene expression at 24 and 48 h compared with the control group. Moreover, the expressions of NKAα1 and NKAα2 were both increased in control and ISO groups after treating with klotho protein; meanwhile, the NKA activity was increased and NCX activity was decreased after treatment. Consistently, the [Ca2+]i level and hypertrophic gene expression were decreased in ISO group after klotho protein treatment. However, these effects were both prevented by transfecting with NKAα2 siRNA. In conclusion, these findings demonstrated that klotho inhibits isoproterenol-induced hypertrophic response in H9C2 cells by activating NKA and inhibiting the reverse mode of NCX and this effect may be associated with the upregulation of NKAα2 expression. 相似文献
4.
Sivaraman P Mattegunta S Subbaraju GV Satyanarayana C Padmanabhan B 《Systems and synthetic biology》2010,4(4):257-263
Sirtuins (class III histone deacetylase) are evolutionarily conserved NAD+-dependent enzymes that catalyze the deacetylation of acetyl-lysine residues of histones and other target proteins. Because
of their associations in various pathophysiological conditions, the identification of small molecule modulators has been of
significant interest. In the present study, virtual screening was carried out with NCI Diversity Set II using crystal structure
of hSIRT2 (PDB ID: 1J8F) as a model for the docking procedure to find potential compounds, which were then subjected to experimental
tests for their in vitro SIRT2 inhibitory activity. One of the 40 compounds tested, NSC671136 (IUPAC name: 6-Acetyl-4-oxo-1,3-diphenyl-2-thioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-5-yl
2,4-dichlorobenzoate) has structurally unique scaffold, showed strong inhibitory activity towards SIRT2 with IC50 of ~8.7 μM and to a lesser extent on SIRT1 activity. The reported compound is substantially potent compared to the published
SIRT2 inhibitors and serves as an excellent base for future lead development. 相似文献
5.
Haibo Xue Weiwei Wang Zhongyan Shan Yuanbin Li Yushu Li Xiaochun Teng Yun Gao Chenling Fan Weiping Teng 《Biological trace element research》2011,143(1):292-301
Iodine is an essential trace element for thyroid hormone synthesis and metabolism, either low or high intake may lead to thyroid
disease, but the pathogenetic mechanisms by which iodine interacts with the thyroid autoimmune are poorly understood. We investigated
the dynamic changes of CD4+CD25+ regulatory T cells in NOD.H-2h4 mice with iodine-induced autoimmune thyroiditis (AIT), and explore potential immune mechanism of AIT induced by iodine. NOD.H-2h4 mice were randomly divided into two groups, and received plain water or water containing 0.005% sodium iodide. Eight weeks
after iodine provision, the incidences of thyroiditis, relative weights of thyroids, and serum thyroglobulin antibody titers
in the iodine-supplied groups were significantly increased compared to the control groups (p < 0.05). The AIT mice had fewer CD4+CD25+Foxp3+ T cells and reduced Foxp3 mRNA expression in splenocytes compared with the controls (p < 0.01), and maintained relatively low levels during the development of thyroiditis. The changes described above aggravated
gradually with the extension of iodine treatment. These data suggest that CD4+CD25+ regulatory T cells may be involved in the pathogenesis and development of AIT induced by iodine. 相似文献
6.
Cristina Maccalli Samantha Scaramuzza Giorgio Parmiani 《Cancer immunology, immunotherapy : CII》2009,58(5):801-808
Innate and adaptive immune responses have many interactions that are regulated by the balance of signals initiated by a variety
of activatory and inhibitory receptors. Among these, the NKG2D molecule was identified as expressed by T lymphocytes, including
most CD8+ cells and a minority of CD4+ cells, designated TNK cells in this paper. Tumor cells may overexpress the stress-inducible NKG2D ligands (NKG2DLs: MICA/B,
ULBPs) and the NKG2D signaling has been shown to be involved in lymphocyte-mediated anti-tumor activity. Aberrant expression
of NKG2DLs by cancer cells, such as the release of soluble form of NKG2DLs, can lead to the impairment of these immune responses.
Here, we discuss the significance of NKG2D in TNK-mediated anti-tumor activity. Our studies demonstrate that NKG2D+ T cells (TNK) are commonly recruited at the tumor site in melanoma patients where they may exert anti-tumor activity by engaging
both TCR and NKG2D. Moreover, NKG2D and TCR triggering was also observed by peripheral blood derived T lymphocyte- or T cell
clone-mediated tumor recognition, both in melanoma and colorectal cancer (CRC) patients. Notably, heterogeneous expression
of NKG2DLs was found in melanoma and CRC cells, with a decrease of these molecules along with tumor progression. Therefore,
through the mechanisms that govern NKG2D engagement in anti-tumor activity and the expression of NKG2DLs by tumor cells that
still need to be dissected, we showed that NKG2D expressing TNK cells are a relevant T cell subtype for immunosurveillance
of tumors and we propose that new immunotherapeutic interventions for cancer patients should be aimed also at enhancing NKG2DLs
expression by tumor cells.
This paper is a focused research review based on a presentation given at the sixth annual meeting of the Association for Immunotherapy
of Cancer (CIMT), held in Mainz, Germany, 15–16 May 2008. 相似文献
7.
We have identified a plasma membrane Na+/H+ exchanger from durum wheat, designated TdSOS1. Heterologous expression of TdSOS1 in a yeast strain lacking endogenous Na+ efflux proteins showed complementation of the Na+- and Li+-sensitive phenotype by a mechanism involving cation efflux. Salt tolerance conferred by TdSOS1 was maximal when co-expressed
with the Arabidopsis protein kinase complex SOS2/SOS3. In vitro phosphorylation of TdSOS1 with a hyperactive form of the Arabidopsis SOS2 kinase (T/DSOS2∆308) showed the importance of two essential serine residues at the C-terminal hydrophilic tail (S1126,
S1128). Mutation of these two serine residues to alanine decreased the phosphorylation of TdSOS1 by T/DSOS2∆308 and prevented
the activation of TdSOS1. In addition, deletion of the C-terminal domain of TdSOS1 encompassing serine residues at position
1126 and 1128 generated a hyperactive form that had maximal sodium exclusion activity independent from the regulatory SOS2/SOS3
complex. These results are consistent with the presence of an auto-inhibitory domain at the C-terminus of TdSOS1 that mediates
the activation of TdSOS1 by the protein kinase SOS2. Expression of TdSOS1 mRNA in young seedlings of the durum wheat variety Om Rabia3, using different abiotic stresses (ionic and oxidative stress)
at different times of exposure, was monitored by RT–PCR. 相似文献
8.
Ischemia followed by reperfusion results in impairment of cellular and mitochondrial functionality due to opening of mitochondrial permeability transition pores. On the other hand, activation of mitochondrial ATP-sensitive K+ channels (mitoKATP) protects the heart against ischemic damage. This study examined the effects of mitoKATP and mitochondrial permeability transition on isolated rat heart mitochondria and cardiac cells submitted to simulated ischemia and reperfusion (cyanide/aglycemia). Both mitoKATP opening, using diazoxide, and the prevention of mitochondrial permeability transition, using cyclosporin A, protected against cellular damage, without additive effects. MitoKATP opening in isolated rat heart mitochondria slightly decreased Ca2+ uptake and prevented mitochondrial reactive oxygen species production, most notably in the presence of added Ca2+. In ischemic cells, diazoxide decreased ROS generation during cyanide/aglycemia while cyclosporin A prevented oxidative stress only during simulated reperfusion. Collectively, these studies indicate that opening mitoKATP prevents cellular death under conditions of ischemia/reperfusion by decreasing mitochondrial reactive oxygen species release secondary to Ca2+ uptake, inhibiting mitochondrial permeability transition. 相似文献
9.
F. Bayat B. Shiran D. V. Belyaev N. O. Yur’eva G. I. Sobol’kova H. Alizadeh M. Khodambashi A. V. Babakov 《Russian Journal of Plant Physiology》2010,57(5):696-706
Two cultivars of potato (Solanum tuberosum L.) were transformed with a barley antiporter gene HvNHX2 driven by the CaMV 35S promoter. The expressed transgene conferred a higher NaCl tolerance to one of the cultivars. Under
salt stress, the more salt-tolerant transgenic plants had longer roots, higher dry weight, and suppressed cell expansion as
compared to wild-type plants. The salt tolerance of the plants grown in vitro was not accompanied by elevated total sodium
in any plant organs tested. Instead, higher potassium was found in roots of transgenic plants. Possible mechanisms of plant
salt tolerance are discussed. 相似文献
10.
Vázquez-Limón C Vega-Badillo J Martínez A Espinosa-Molina G Gosset G Soberón X López-Munguía A Osuna J 《Biotechnology letters》2007,29(12):1857-1863
By complementing a non-fermentative Escherichia coli (ldhA
−
pflB
−) strain with the recombinant Zymomonas mobilis ethanol pathway (pdc, adhB), we evaluated the effect of different levels of enzymatic activity on growth rate demonstrating that there is a direct relationship
between anaerobic growth rate and the total specific activity of pyruvate decarboxylase, which is the limiting enzyme of this
specific fermentative NAD+ regenerating pathway. This relationship was proved to be useful to establish a selection strategy based on growth rate for
the analysis of lctE libraries, which encode lactate dehydrogenase from Bacillus subtilis. 相似文献
11.
The expression of Na+, K+-ATPase α3 subunit and synaptosomal membrane Na+, K+-ATPase activity were analyzed after administration of ouabain and endobain E, respectively commercial and endogenous Na+, K+-ATPase inhibitors. Wistar rats received intracerebroventricularly ouabain or endobain E dissolved in saline solution or Tris–HCl,
respectively or the vehicles (controls). Two days later, animals were decapitated, cerebral cortex and hippocampus removed
and crude and synaptosomal membrane fractions were isolated. Western blot analysis showed that Na+, K+-ATPase α3 subunit expression increased roughly 40% after administration of 10 or 100 nmoles ouabain in cerebral cortex but
remained unaltered in hippocampus. After administration of 10 μl endobain E (1 μl = 28 mg tissue) Na+, K+-ATPase α3 subunit enhanced 130% in cerebral cortex and 103% in hippocampus. The activity of Na+, K+-ATPase in cortical synaptosomal membranes diminished or increased after administration of ouabain or endobain E, respectively.
It is concluded that Na+, K+-ATPase inhibitors modify differentially the expression of Na+, K+-ATPase α3 subunit and enzyme activity, most likely involving compensatory mechanisms. 相似文献
12.
Intracellular NADPH/NADP+ ratio in cells grown on various production media with different carbon and nitrogen sources had a positive correlation with
the thymidine production. To improve thymidine production in a previously engineered E. coli strain, NAD+ kinase was overexpressed in it resulting in the NADPH/NADP+ ratio shifting from 0.184 to 0.267. The [NADH + NADP+]/[NAD+ + NADPH] ratio was, however, not significantly altered. In jar fermentation, 740 mg thymidine l−1 was produced in parental strain, while 940 mg l−1 of thymidine was produced in NAD+ kinase-expressing strain. 相似文献
13.
The effect of ANG II on pHi, [Ca2+]i and cell volume was investigated in T84 cells, a cell line originated from colon epithelium, using the probes BCECF-AM, Fluo
4-AM and acridine orange, respectively. The recovery rate of pHi via the Na+/H+ exchanger was examined in the first 2 min following the acidification of pHi with a NH4Cl pulse. In the control situation, the pHi recovery rate was 0.118 ± 0.001 (n = 52) pH units/min and ANG II (10−12 M or 10−9 M) increased this value (by 106% or 32%, respectively) but ANG II (10−7 M) decreased it to 47%. The control [Ca2+]i was 99 ± 4 (n = 45) nM and ANG II increased this value in a dose-dependent manner. The ANG II effects on cell volume were minor and late
and should not interfere in the measurements of pHi recovery and [Ca2+]i. To document the signaling pathways in the hormonal effects we used: Staurosporine (a PKC inhibitor), W13 (a calcium-dependent
calmodulin antagonist), H89 (a PKA inhibitor) or Econazole (an inhibitor of cytochrome P450 epoxygenase). Our results indicate
that the biphasic effect of ANG II on Na+/H+ exchanger is a cAMP-independent mechanism and is the result of: 1) stimulation of the exchanger by PKC signaling pathway
activation (at 10−12 – 10−7 M ANG II) and by increases of [Ca2+]i in the lower range (at 10−12 M ANG II) and 2) inhibition of the exchanger at high [Ca2+]i levels (at 10−9 – 10−7 M ANG II) through cytochrome P450 epoxygenase-dependent metabolites of the arachidonic acid signaling pathway. 相似文献
14.
Ca2+ concentration in retinal photoreceptor rod outer segment (OS) strongly affects the generator potential kinetics and the receptor
light adaptation. The response to intense light stimuli delivered in the dark produce potential changes exceeding 40 mV: since
the Ca2+ extrusion in the OS is entirely controlled by the Na+:Ca2+, K+ exchanger, it is important to assess how the exchanger ion transport rate is affected by the voltage and, in general, by
intracellular factors. It is indeed known that the cardiac Na+:Ca2+ exchanger is regulated by Mg-ATP via a still unknown metabolic pathway. In the present work, the Na+:Ca2+, K+ exchanger regulation was investigated in isolated OS, recorded in whole-cell configuration, using ionic conditions that activated
maximally the exchanger in both forward and reverse mode. In all species examined (amphibia: Rana esculenta and Ambystoma mexicanum; reptilia: Gecko gecko), the forward (reverse) exchange current increased about linearly for negative (positive) voltages and exhibited outward
(inward) rectification for positive (negative) voltages. Since hyperpolarisation increases Ca2+ extrusion rate, the recovery of the dark level of Ca2+ (and, in turn, of the generator potential) after intense light stimuli results accelerated. Mg-ATP increased the size of
forward and reverse exchange current by a factor of ∼2.3 and ∼2.6, respectively, without modifying their voltage dependence.
This indicates that Mg-ATP regulates the number of active exchanger sites and/or the exchanger turnover number, although via
an unknown mechanism.
Proceedings of the XVIII Congress of the Italian Society of Pure and Applied Biophysics (SIBPA), Palermo, Sicily, September
2006. 相似文献
15.
A. T. Eprintsev M. O. Gataullina M. S. Lyashchenko 《Applied Biochemistry and Microbiology》2016,52(4):366-370
Malate dehyrogenase isoforms (46- and 70-fold purifications) with specific activities of the 640 and 990 U/mg protein were obtained in an electrophoretically homogeneous state from maize mesophyll. The physicochemical and catalytic properties of these isoforms were studied. The molecular weight and the Michaelis constants were determined; the effect of hydrogen ions on the forward and reverse MDH reaction was studied. The results of SDS-PAGE demonstrated that malate dehydrogenase isoforms have an oligomeric structure comprised of identical subunits. The first isoform with a molecular weight of 126.58 kDa is tetramer, and the second isoform with a molecular weight of 63.3 is dimer. 相似文献
16.
L. Yang H. Liu S. M. Fu H. M. Ge R. J. Tang Y. Yang H. H. Wang H. X. Zhang 《Biologia Plantarum》2017,61(4):641-650
The tonoplast and plasma membrane localized sodium (potassium)/proton antiporters have been shown to play an important role in plant resistance to salt stress. In this study, AtNHX1 and AtNHX3, two tonoplast Na+(K+)/H+ antiporter encoding genes from Arabidopsis thaliana, were expressed in poplar to investigate their biological functions in the resistance to abiotic stresses in woody plants. Transgenic poplar plants expressing either gene exhibited increased resistance to both salt and water-deficit stresses. Compared to the wild type (WT) plants, transgenic plants accumulated more sodium and potassium ions in the presence of 100 mM NaCl and showed reduced electrolyte leakage in the leaves under water stress. Furthermore, the proton-translocating and cation-dependent H+ (Na+/H+ or K+/H+) exchange activities in the tonoplast vesicles isolated from the leaves of transgenic plants were higher than in those isolated from WT plants. Therefore, constitutive expression of either AtNHX1 or AtNHX3 genetically modified the salt and water stress tolerance of transgenic poplar plants, providing a potential tool for engineering tree species with enhanced resistance to multiple abitotic stresses. 相似文献
17.
Osteoclasts are multinucleated giant cells that originate from a monocyte/macrophage lineage, and are involved in the inflammatory bone destruction accompanied by periodontitis. Recent studies have shown that osteoclast precursors reside not only in the bone marrow, but also in the peripheral blood and spleen, though the precise characteristics of each precursor have not been analyzed. We hypothesized that the number of osteoclast precursors in those tissues may increase under pathological conditions and contribute to osteoclast formation in vivo in a mouse model. To test this hypothesis, we attempted to identify cell populations that possess osteoclast differentiation potential in the bone marrow, spleen, and blood by analyzing macrophage/monocyte-related cell surface markers such as CD11b, CD14, and colony-stimulating factor-1 receptor (c-Fms). In the bone marrow, the CD11b? cell population, but not the CD11b+ cell population, differentiated into osteoclasts in the presence of receptor activator of nuclear factor-κB ligand and macrophage colony-stimulating factor. On the other hand, in the spleen and blood, CD11b+ cells differentiated into osteoclasts. Interestingly, lipopolysaccharide (LPS) administration to the mice dramatically increased the proportion of CD11b+ c-Fms+ CD14+ cells, which differentiated into osteoclasts, in the bone marrow and spleen. These results suggest that LPS administration increases the proportion of a distinct cell population expressing CD11b+, c-Fms+, and CD14+ in the bone marrow and spleen. Thus, these cell populations are considered to contribute to the increase in osteoclast number during inflammatory bone destruction such as periodontitis. 相似文献
18.
Wei-Wei Zhang Jing-Jing Meng Jin-Yi Xing Sha Yang Feng Guo Xin-Guo Li Shu-Bo Wan 《Journal of Plant Biology》2017,60(3):259-267
High salinity is the one of important factors limiting plant growth and crop production. Many NHX-type antiporters have been reported to catalyze K+/H+ exchange to mediate salt stress. This study shows that an NHX gene from Arachis hypogaea L. has an important role in K+ uptake and transport, which affects K+ accumulation and plant salt tolerance. When overexpressing AhNHX1, the growth of tobacco seedlings is improved with longer roots and a higher fresh weight than the wild type (WT) under NaCl treatment. Meanwhile, when exposed to NaCl stress, the transgenic seedlings had higher K+/H+ antiporter activity and their roots got more K+ uptake. NaCl stress could induce higher K+ accumulation in the roots, stems, and leaves of transgenic tobacco seedlings but not Na+ accumulation, thus, leading to a higher K+/Na+ ratio in the transgenic seedlings. Additionally, the AKT1, HAK1, SKOR, and KEA genes, which are involved in K+ uptake or transport, were induced by NaCl stress and kept higher expression levels in transgenic seedlings than in WT seedlings. The H+-ATPase and H+-PPase activities were also higher in transgenic seedlings than in the WT seedlings under NaCl stress. Simultaneously, overexpression of AhNHX1 increased the relative distribution of K+ in the aerial parts of the seedlings under NaCl stress. These results showed that AhNHX1 catalyzed the K+/H+ antiporter and enhanced tobacco tolerance to salt stress by increasing K+ uptake and transport. 相似文献
19.
Jaromír Plášek David Babuka Milan Hoefer 《Journal of bioenergetics and biomembranes》2017,49(5):391-397
According to the common view, weak acid uncouplers increase proton conductance of biological (and phospholipid bilayer) membranes, thus effecting H+ fluxes driven by their electrochemical gradients. Under certain conditions, however, uncouplers can induce unexpected effects opposite to the dissipation of H+ gradients. Results are presented here demonstrating CCCP-induced proton influx into Saccharomyces cerevisiae cytosol driven by the electrochemical potentials of CCCP and its CCCP? anions, independent of electrochemical H+-gradient. Another view of week acid uncouplers’ action is proposed that is logically consistent with these observations. 相似文献
20.
David A Horwitz 《Arthritis research & therapy》2010,12(1):101
Various abnormalities in CD4+CD25+ regulatory T cells (Tregs) in systemic lupus erythematosus (SLE) include increased Foxp3+ cells that are CD25 negative. Barring methodological technical factors, these cells could be atypical Tregs or activated
non-Treg CD4+ cells that express Foxp3. Two groups have reached opposite conclusions that could possibly reflect the subjects studied.
One group studied untreated new-onset SLE and suggested that these T cells were mostly CD25-Foxp3+ non-Tregs. The other group studied patients with long-standing disease and suggested that these cells are mostly dysfunctional
Tregs. A third group reported increased Foxp3+CD4+CD25dim rather than CD25- cells in active SLE and these were also non-Tregs. Thus, it is likely that not all Foxp3+ T cells in SLE have protective suppressive activity. 相似文献