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1.
Jingdong Long Xiaolu Lei Meiyun Chen Shulei Yang Tao Sun Junwei Zeng Deqian Yu Hong Tian Xiaohong Liu 《Neurochemical research》2018,43(2):267-275
Spinal cannabinoid receptor 1 (CB1R) and purinergic P2X receptors (P2XR) play a critical role in the process of pathological pain. Both CB1R and P2XR are expressed in spinal dorsal horn (DH) neurons. It is not clear whether CB1 receptor activation modulates the function of P2X receptor channels within dorsal horn. For this reason, we observed the effect of CP55940 (cannabinoid receptor agonist) on ATP-induced Ca2+ mobilization in cultured rat DH neurons. The changes of intracellular calcium concentration ([Ca2+]i) were detected with confocal laser scanning microscopy using fluo-4/AM as a calcium fluorescent indicator. 100 μM ATP caused [Ca2+]i increase in cultured DH neurons. ATP-evoked [Ca2+]i increase in DH neurons was blocked by chelating extracellular Ca2+ and P2 purinoceptor antagonist PPADS. At the same time, ATP-γ-S (a non-hydrolyzable ATP analogue) mimicked the ATP action, while P2Y receptor agonist ADP failed to evoke [Ca2+]i increase in cultured DH neurons. These data suggest that ATP-induced [Ca2+]i elevation in cultured DH neurons is mediated by P2X receptor. Subsequently, we noticed that, in cultured rat DH neurons, ATP-induced Ca2+ mobilization was inhibited after pretreated with CP55940 with a concentration-dependent manner, which implies that the opening of P2X receptor channels are down-regulated by activation of cannabinoid receptor. The inhibitory effect of CP55940 on ATP-induced Ca2+ response was mimicked by ACEA (CB1R agonist), but was not influenced by AM1241 (CB2R agonist). Moreover, the inhibitory effect of CP55940 on ATP-induced Ca2+ mobilization was blocked by AM251 (CB1 receptor antagonist), but was not influenced by AM630 (CB2 receptor antagonist). In addition, we also observed that forskolin (an activator of adenylate cyclase) and 8-Br-cAMP (a cell-permeable cAMP analog) reversed the inhibitory effect of CP55940, respectively. In a summary, our observations raise a possibility that CB1R rather than CB2R can downregulate the opening of P2X receptor channels in DH neurons. The reduction of cAMP/PKA signaling is a key element in the inhibitory effect of CB1R on P2X-channel-induced Ca2+ mobilization. 相似文献
2.
Although taurine and glutamate are the most abundant amino acids conducting neural signals in the central nervous system, the communication between these two neurotransmitters is largely unknown. This study explores the interaction of taurine and glutamate in the retinal third-order neurons. Using specific antibodies, both taurine and taurine transporters were localized in photoreceptors and Off-bipolar cells, glutamatergic neurons in retinas. It is possible that Off-bipolar cells release juxtaposed glutamate and taurine to activate the third-order neurons in retina. The interaction of taurine and glutamate was studied in acutely dissociated third-order neurons in whole-cell patch-clamp recording and Ca2+ imaging. We find that taurine effectively reduces glutamate-induced Ca2+ influx via ionotropic glutamate receptors and voltage-dependent Ca2+ channels in the neurons, and the effect of taurine was selectively inhibited by strychnine and picrotoxin, but not GABA receptor antagonists, although GABA receptors are present in the neurons. A CaMKII inhibitor partially reversed the effect of taurine, suggesting that a Ca2+/calmodulin-dependent pathway is involved in taurine regulation. On the other hand, a rapid influx of Ca2+ through ionotropic glutamate receptors could inhibit the amplitude and kinetics of taurine-elicited currents in the third-order neurons, which could be controlled with intracellular application of BAPTA a fast Ca2+ chelator. This study indicates that taurine is a potential neuromodulator in glutamate transmission. The reciprocal inhibition between taurine and glutamate in the postsynaptic neurons contributes to computation of visual signals in the retinal neurons. 相似文献
3.
Bak LK Ziemińska E Waagepetersen HS Schousboe A Albrecht J 《Neurochemical research》2008,33(2):273-278
One of the forms of phosphate activated glutaminase (PAG) is associated with the inner mitochondrial membrane. It has been
debated whether glutamate formed from glutamine in the reaction catalyzed by PAG has direct access to mitochondrial or cytosolic
metabolism. In this study, metabolism of [U-13C]glutamine (3 mM) or [U-13C]glutamate (10 mM) was investigated in isolated rat brain mitochondria. The presence of a functional tricarboxylic (TCA)
cycle in the mitochondria was tested using [U-13C]succinate as substrate and extensive labeling in aspartate was seen. Accumulation of glutamine into the mitochondrial matrix
was inhibited by histidine (15 mM). Extracts of mitochondria were analyzed for labeling in glutamine, glutamate and aspartate
using liquid chromatography-mass spectrometry. Formation of [U-13C]glutamate from exogenous [U-13C]glutamine was decreased about 50% (P < 0.001) in the presence of histidine. In addition, the 13C-labeled skeleton of [U-13C]glutamine was metabolized more vividly in the tricarboxylic acid (TCA) cycle than that from [U-13C]glutamate, even though glutamate was labeled to a higher extent in the latter condition. Collectively the results show that
transport of glutamine into the mitochondrial matrix may be a prerequisite for deamidation by PAG.
Special issue article in honor of Dr. Frode Fonnum.
Lasse K. Bak and Elżbieta Ziemińska contributed equally to the experimental work described in this paper. 相似文献
4.
Glutamine-free culture of Vero cells has previously been shown to cause higher cell yield and lower ammonia accumulation than
that in glutamine-containing culture. Nitrogen metabolism of asparagine and glutamate as glutamine replacer was studied here
using nuclear magnetic resonance (NMR) spectroscopy. 15N-labelled glutamate or asparagine was added and their incorporation into nitrogenous metabolites was monitored by heteronuclear
multiple bond coherence (HMBC) NMR spectroscopy. In cells incubated with l-[15N]glutamate, the 15N label was subsequently found in a number of metabolites including alanine, aspartate, proline, and an unidentified compound.
No detectable signal occurred, indicating that glutamate was utilized by transamination rather than by oxidative deamination. In cells
incubated with l-[2-15N]asparagine, the 15N label was subsequently found in aspartate, the amine group of glutamate/glutamine, and in two unidentified compounds. Incubation
of cells with l-[4-15N]asparagine showed that the amide nitrogen of asparagine was predominantly transferred to glutamine amide. There was no detectable
production of , showing that most of the asparagine amide was transaminated by asparagine synthetase rather than deaminated by asparaginase.
Comparing with a glutamine-containing culture, the activities of phosphate-activated glutaminase (PAG), glutamate dehydrogenase
(GDH) and alanine aminotransferase (ALT) decreased significantly and the activity of aspartate aminotransferase (AST) decreased
slightly. 相似文献
5.
Youlin Xia Paolo Rossi Marco Tonelli Chengdong Huang Charalampos G. Kalodimos Gianluigi Veglia 《Journal of biomolecular NMR》2017,69(1):45-52
TROSY-based triple resonance experiments are essential for protein backbone assignment of large biomolecular systems by solution NMR spectroscopy. In a survey of the current Bruker pulse sequence library for TROSY-based experiments we found that several sequences were plagued by artifacts that affect spectral quality and hamper data analysis. Specifically, these experiments produce sidebands in the 13C(t 1) dimension with inverted phase corresponding to 1HN resonance frequencies, with approximately 5% intensity of the parent 13C crosspeaks. These artifacts originate from the modulation of the 1HN frequency onto the resonance frequency of 13Cα and/or 13Cβ and are due to 180° pulses imperfections used for 1H decoupling during the 13C(t 1) evolution period. These sidebands can become severe for CAi, CAi?1 and/or CBi, CBi?1 correlation experiments such as TROSY-HNCACB. Here, we implement three alternative decoupling strategies that suppress these artifacts and, depending on the scheme employed, boost the sensitivity up to 14% on Bruker spectrometers. A class of comparable Agilent/Varian pulse sequences that use WALTZ16 1H decoupling can also be improved by this method resulting in up to 60–80% increase in sensitivity. 相似文献
6.
Cd2+ is highly toxic to Staphylococcus aureus since it blocks dithiols in cytoplasmic 2-oxoglutarate dehydrogenase complex (ODHC) participating in energy conservation process. However, S. aureus 17810R is Cd2+-resistant due to possession of cadA-coded Cd2+ efflux system, recognized here as P-type Cd2+-ATPase. This Cd2+ pump utilizing cellular energy—ATP, ?μ H + (electrochemical proton potential) and respiratory protons, extrudes Cd2+ from cytoplasm to protect dithiols in ODHC, but the mechanism of Cd2+ extrusion remains unknown. Here we propose that two Cd2+ taken up by strain 17810R via Mn2+ uniporter down membrane potential (?ψ) generated during glutamate oxidation in 100 mM phosphate buffer (high PiB) are trapped probably by high affinity sites in cytoplasmic domain of Cd2+-ATPase, forming SCdS. This stops Cd2+ transport towards dithiols in ODHC, allowing undisturbed NADH production, its oxidation and energy conservation, while ATP could change orientation of SCdS towards facing transmembrane channel. Now, increased number of Pi-dependent protons pumped electrogenically via respiratory chain and countertransported through the channel down ?ψ, extrude two trapped cytoplasmic Cd2+, which move to low affinity sites, being then extruded into extracellular space via ?ψ-dependent Cd2+/H+ exchange. In 1 mM phosphate buffer (low PiB), external Cd2+ competing with decreased number of Pi-dependent protons, binds to ψs of Cd2+-ATPase channel, enters cytoplasm through the channel down ?ψ via Cd2+/Cd2+ exchange and blocks dithiols in ODHC. However, Mg2+ pretreatment preventing external Cd2+ countertransport through the channel down ?ψ, allowed undisturbed NADH production, its oxidation and extrusion of two cytoplasmic Cd2+ via Cd2+/H+ exchange, despite low PiB. 相似文献
7.
Anant B. Patel James C. K. Lai Golam I. M. Chowdhury Douglas L. Rothman Kevin L. Behar 《Neurochemical research》2017,42(1):173-190
The 13C turnover of neurotransmitter amino acids (glutamate, GABA and aspartate) were determined from extracts of forebrain nerve terminals and brain homogenate, and fronto-parietal cortex from anesthetized rats undergoing timed infusions of [1,6-13C2]glucose or [2-13C]acetate. Nerve terminal 13C fractional labeling of glutamate and aspartate was lower than those in whole cortical tissue at all times measured (up to 120 min), suggesting either the presence of a constant dilution flux from an unlabeled substrate or an unlabeled (effectively non-communicating on the measurement timescale) glutamate pool in the nerve terminals. Half times of 13C labeling from [1,6-13C2]glucose, as estimated by least squares exponential fitting to the time course data, were longer for nerve terminals (GluC4, 21.8 min; GABAC2 21.0 min) compared to cortical tissue (GluC4, 12.4 min; GABAC2, 14.5 min), except for AspC3, which was similar (26.5 vs. 27.0 min). The slower turnover of glutamate in the nerve terminals (but not GABA) compared to the cortex may reflect selective effects of anesthesia on activity-dependent glucose use, which might be more pronounced in the terminals. The 13C labeling ratio for glutamate-C4 from [2-13C]acetate over that of 13C-glucose was twice as large in nerve terminals compared to cortex, suggesting that astroglial glutamine under the 13C glucose infusion was the likely source of much of the nerve terminal dilution. The net replenishment of most of the nerve terminal amino acid pools occurs directly via trafficking of astroglial glutamine. 相似文献
8.
The synergistic benefits of the dual inoculation of legumes with nodule bacteria and arbuscular mycorrhizae (AM) are well
established, but the effect of an external NH4+ supply on this tripartite relationship is less clear. This effect of NH4+ supply was investigated with regards to the growth and function of the legume host and both symbionts. Nodulated Phaseolus vulgaris seedlings with and without AM, were grown in a sand medium with either 0 N, 1 mM or 3 mM NH4+. Plants were harvested at 30 days after emergence and measurements were taken for biomass, N2 fixation, photosynthesis, asparagine concentration, construction costs and N nutrition. The addition of NH4+ led to a decline in the percentage AM colonization and nodule dry weights, although AM colonization was affected to a lesser
extent. NH4+ supply also resulted in a decrease in the reliance on biological nitrogen fixation (BNF); however, the AM roots maintained
higher levels of NH4+ uptake than their non-AM counterparts. Furthermore, the non-AM plants had a higher production of asparagine than the AM plants.
The inhibitory effects of NH4+ on nodule function can be reduced by the presence of AM at moderate levels of NH4+ (1 mM), via improving nodule growth or relieving the asparagine-induced inhibition of BNF. 相似文献
9.
E. V. Stelmashook E. E. Genrikhs O. P. Aleksandrova G. A. Amelkina E. A. Zelenova N. K. Isaev 《Biochemistry. Biokhimii?a》2016,81(8):899-905
Rat cultured cerebellar granule neurons (CGNs) were not sensitive to CuCl2 (1-10 µM, 24 h), whereas paraquat (150 µM) decreased neuronal survival to 79 ± 3% of control level. Simultaneous treatment of CGNs with paraquat and CuCl2 (2, 5, or 10 µM Cu2+/paraquat) caused significant copper dose-dependent death, lowering their survival to 56 ± 4, 37 ± 3, or 16 ± 2%, respectively, and stimulating elevated production of free radicals in CGNs. Introduction of vitamin E, a non-competitive antagonist of NMDA subtype of glutamate receptors (MK-801), and also removal of glutamine from the incubation medium decreased toxicity of Cu2+/paraquat mixture. However, addition of Cu2+ into the incubation medium did not affect CGNs death caused by glutamate. These data emphasize that excessive copper in the brain may trigger oxidative stress, which in turn results in release of glutamate, overstimulation of glutamate receptors, and neuronal death. 相似文献
10.
Sergio Arrabal Miguel Angel Lucena Miren Josune Canduela Almudena Ramos-Uriarte Patricia Rivera Antonia Serrano Francisco Javier Pavón Juan Decara Antonio Vargas Elena Baixeras Mercedes Martín-Rufián Javier Márquez Pedro Fernández-Llébrez Baukje De Roos Pedro Grandes Fernando Rodríguez de Fonseca Juan Suárez 《PloS one》2015,10(12)
Cannabinoid CB1 receptors peripherally modulate energy metabolism. Here, we investigated the role of CB1 receptors in the expression of glucose/pyruvate/tricarboxylic acid (TCA) metabolism in rat abdominal muscle. Dihydrolipoamide dehydrogenase (DLD), a flavoprotein component (E3) of α-ketoacid dehydrogenase complexes with diaphorase activity in mitochondria, was specifically analyzed. After assessing the effectiveness of the CB1 receptor antagonist AM251 (3 mg kg-1, 14 days) on food intake and body weight, we could identified seven key enzymes from either glycolytic pathway or TCA cycle—regulated by both diet and CB1 receptor activity—through comprehensive proteomic approaches involving two-dimensional electrophoresis and MALDI-TOF/LC-ESI trap mass spectrometry. These enzymes were glucose 6-phosphate isomerase (GPI), triosephosphate isomerase (TPI), enolase (Eno3), lactate dehydrogenase (LDHa), glyoxalase-1 (Glo1) and the mitochondrial DLD, whose expressions were modified by AM251 in hypercaloric diet-induced obesity. Specifically, AM251 blocked high-carbohydrate diet (HCD)-induced expression of GPI, TPI, Eno3 and LDHa, suggesting a down-regulation of glucose/pyruvate/lactate pathways under glucose availability. AM251 reversed the HCD-inhibited expression of Glo1 and DLD in the muscle, and the DLD and CB1 receptor expression in the mitochondrial fraction. Interestingly, we identified the presence of CB1 receptors at the membrane of striate muscle mitochondria. DLD over-expression was confirmed in muscle of CB
1
-/- mice. AM251 increased the pyruvate dehydrogenase and glutathione reductase activity in C2C12 myotubes, and the diaphorase/oxidative activity in the mitochondria fraction. These results indicated an up-regulation of methylglyoxal and TCA cycle activity. Findings suggest that CB1 receptors in muscle modulate glucose/pyruvate/lactate pathways and mitochondrial oxidative activity by targeting DLD. 相似文献
11.
《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1999,122(3):327-330
The influence of saturated and unsaturated fatty acid ethanolamides as well as Δ9-tetrahydrocannabinol (Δ9-THC), WIN 55,212-2 and cannabinoid CB1 receptor antagonist SR 141716 on sea urchin fertilization was studied. The ethanolamides of arachidonic, oleic and linoleic acids but not saturated fatty acid (C14–C20) derivatives inhibited fertilization when pre-incubated with sperm cells. Δ9-THC and WIN 55,212-2 also inhibited fertilization, Δ9-THC being ten times as potent as WIN 55,212-2. Selective cannabinoid CB1 receptor antagonist SR 141716 also blocked fertilization and did not antagonize the action of Δ9-THC. The obtained results indicate that different unsaturated fatty acid ethanolamides may control sea urchin fertilization, and that sea urchin sperm cell cannabinoid receptor may differ from the known cannabinoid receptor subtypes. 相似文献
12.
Basetti Madhu Greg L. Shaw Anne Y. Warren David E. Neal John R. Griffiths 《Metabolomics : Official journal of the Metabolomic Society》2016,12(7):120
Introduction
The androgen receptor (AR) is the master regulator of prostate cancer cell metabolism. Degarelix is a novel gonadotrophin-releasing hormone blocker, used to decrease serum androgen levels in order to treat advanced human prostate cancer. Little is known of the rapid metabolic response of the human prostate cancer tissue samples to the decreased androgen levels.Objectives
To investigate the metabolic responses in benign and cancerous tissue samples from patients after treatment with Degarelix by using HRMAS 1H NMR spectroscopy.Methods
Using non-destructive HR-MAS 1H NMR spectroscopy we analysed the metabolic changes induced by decreased AR signalling in human prostate cancer tissue samples. Absolute concentrations of the metabolites alanine, lactate, glutamine, glutamate, citrate, choline compounds [t-choline = choline + phosphocholine (PC) + glycerophosphocholine (GPC)], creatine compounds [t-creatine = creatine (Cr) + phosphocreatine (PCr)], taurine, myo-inositol and polyamines were measured in benign prostate tissue samples (n = 10), in prostate cancer specimens from untreated patients (n = 7) and prostate cancer specimens from patients treated with Degarelix (n = 6).Results
Lactate, alanine and t-choline concentrations were significantly elevated in high-grade prostate cancer samples when compared to benign samples in untreated patients. Decreased androgen levels resulted in significant decreases of lactate and t-choline concentrations in human prostate cancer biopsies.Conclusions
The reduced concentrations of lactate and t-choline metabolites due to Degarelix could in principle be monitored by in vivo 1H MRS, which suggests that it would be possible to monitor the effects of physical or chemical castration in patients by that non-invasive method.13.
Yun-Bo Guo Ya Wen Wen-Xue Gao Jing-Chao Li Peng Zhou Zai-Ling Bai Bo Zhang Shi-Qiang Wang 《生物学前沿》2010,5(4):369-377
In dividing embryos, a localized elevation in intracellular Ca2+ ([Ca2+]i) at the cleavage furrow has been shown to be essential for cytokinesis. However, the underlying mechanisms for generating
and maintaining these [Ca2+]i gradients throughout cytokinesis are not fully understood. In the present study, we analyzed the role of inositol 1,4,5-trisphosphate
receptors (IP3Rs) and endoplasmic reticulum (ER) distribution in determining the intracellular Ca2+ gradients in early zebrafish blastomeres. Application of the injected Ca2+ indicator, Indo-1, showed that during the first cell division a standing Ca2+ gradient was formed ∼35 min after fertilization, with the [Ca2+]i spatially decaying from 500–600 nmol/L at the cleavage furrow to 100–200 nmol/L around the nucleus. While the IP3R immunohistochemical
fluorescence was relatively concentrated in the peri-furrow region, ER labeling was relatively enriched in both peri-furrow
and peri-nuclear regions. Numeric simulation suggested that a divergence in the spatial distribution of IP3R and the locations
of Ca2+ uptake within the ER was essential for the formation of a standing Ca2+ gradient, and the Ca2+ gradient could only be well-established under an optimal stoichiometry of Ca2+ uptake and release. Indeed, while inhibition of IP3R Ca2+ release blocked the generation of the Ca2+ gradient at a lower [Ca2+]i level, both Ca2+ release stimulation by inositol 1,4,5-trisphosphate (IP3) injection and ER Ca2+ pump inhibition by cyclopiazonic acid also eliminated the Ca2+ gradients at higher [Ca2+]i levels. Our results suggest a dynamic relationship between ER-mediated Ca2+ release and uptake that underlies the maintenance of the perifurrow Ca2+ gradient and is essential for cytokinesis of zebrafish embryos. 相似文献
14.
Donald C. R. Hauser M. Levandowsky S. H. Hutner L. Chunosoff J. S. Hollwitz 《Microbial ecology》1975,1(1):246-254
Chemosensory responses by the colorles inshore marine dinoflagellateCrypthecodinium cohnii were observed in quadrant-divided Petri plates containing an agar layer + liquid overlay. A suspension of organisms in salt solution was poured onto this and allowed to stand 3 hr. A differential tendency of the cells to become firmly attached or embedded in the substratum was observed when various substances were incorporated in the gel. A positive response (tendency to attach) occurred with: α-l-fucose, dimethyl-β-propiothetin, betaine, sucrose, glycine, L-alanine, hemin, and fructose; negative response: formalin, glutathione, acid hydrolyzed agar, protamine SO4, L-glutamic acid, lactose, glutamine, taurine, L-aspartic acid, putrescine 2 HCl, choline citrate, choline bitartrate, K citrate, and choline HCl. γ-Aminobutyric acid was negative or positive dependeng on concentration. Dead or immotile cells did not become attached. The following compounds elicited no response: α-D-fucose, dimethyl acetothetin chloride, cyclic AMP, and glucose. 相似文献
15.
Linn H. Nilsen Torun M. Melø Oddbjørn Sæther Menno P. Witter Ursula Sonnewald 《Journal of neurochemistry》2012,123(4):532-541
We investigated metabolite levels during the progression of pathology in McGill‐R‐Thy1‐APP rats, a transgenic animal model of Alzheimer's disease, and in healthy age‐matched controls. Rats were subjected to in vivo 1H magnetic resonance spectroscopy (MRS) of the dorsal hippocampus at age 3, 9 and 12 months and of frontal cortex at 9 and 12 months. At 3 months, a stage in which only Aβ oligomers are present, lower glutamate, myo‐inositol and total choline content were apparent in McGill‐R‐Thy1‐APP rats. At age 9 months, lower levels of glutamate, GABA, N‐acetylaspartate and total choline and elevated myo‐inositol and taurine were found in dorsal hippocampus, whereas lower levels of glutamate, GABA, glutamine and N‐acetylaspartate were found in frontal cortex. At age 12 months, only the taurine level was significantly different in dorsal hippocampus, whereas taurine, myo‐inositol, N‐acetylaspartate and total creatine levels were significantly higher in frontal cortex. McGill‐R‐Thy1‐APP rats did not show the same changes in metabolite levels with age as displayed in the controls, and overall, prominent and complex metabolite differences were evident in this transgenic rat model of Alzheimer's disease. The findings also demonstrate that in vivo 1H MRS is a powerful tool to investigate disease‐related metabolite changes in the brain. 相似文献
16.
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
17.
Capo JA Mandal PK Eyyunni S Ahearn GA 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2005,175(1):13-20
The lobster (Homarus americanus) hepato-pancreatic epithelial baso-lateral cell membrane possesses three transport proteins that transfer calcium between the cytoplasm and hemolymph: an ATP-dependent calcium ATPase, a sodium-calcium exchanger, and a verapamil-sensitive cation channel. We used standard centrifugation methods to prepare purified hepato-pancreatic baso-lateral membrane vesicles and a rapid filtration procedure to investigate whether 65Zn2+ transfer across this epithelial cell border occurs by any of these previously described transporters for calcium. Baso-lateral membrane vesicles were osmotically reactive and exhibited a time course of uptake that was linear for 10–15 s and approached equilibrium by 120 s. In the absence of sodium, 65Zn2+ influx was a hyperbolic function of external zinc concentration and followed the Michaelis-Menten equation for carrier transport. This carrier transport was stimulated by the addition of 150 M ATP (increase in Km and Jmax) and inhibited by the simultaneous presence of 150 mol l–1 ATP+250 mol l–1 vanadate (decrease in both Km and Jmax). In the absence of ATP, 65Zn2+ influx was a sigmoidal function of preloaded vesicular sodium concentration (0, 5, 10, 20, 30, 45, and 75 mmol l–1) and exhibited a Hill Coefficient of 4.03±1.14, consistent with the exchange of 3 Na+/1Zn2+. Using Dixon analysis, calcium was shown to be a competitive inhibitor of baso-lateral membrane vesicle 65Zn2+ influx by both the ATP-dependent (Ki=205 nmol l–1 Ca2+) and sodium-dependent (Ki=2.47 mol l–1 Ca2+) transport processes. These results suggest that zinc transport across the lobster hepato-pancreatic baso-lateral membrane largely occurred by the ATP-dependent calcium ATPase and sodium-calcium exchanger carrier proteins.Communicated by: I.D. Hume 相似文献
18.
Srinivasan Sundararaj Dmitry Shishmarev Yiechang Lin Shouvik Aditya Marco G. Casarotto 《Biomolecular NMR assignments》2018,12(2):253-257
Ahnak is a ~?700 kDa polypeptide that was originally identified as a tumour-related nuclear phosphoprotein, but later recognized to play a variety of diverse physiological roles related to cell architecture and migration. A critical function of Ahnak is modulation of Ca2+ signaling in cardiomyocytes by interacting with the β subunit of the L-type Ca2+ channel (CaV1.2). Previous studies have identified the C-terminal region of Ahnak, designated as P3 and P4 domains, as a key mediator of its functional activity. We report here the nearly complete 1H, 13C and 15N backbone NMR chemical shift assignments of the 11 kDa C-terminal P4 domain of Ahnak. This study lays the foundations for future investigations of functional dynamics, structure determination and interaction site mapping of the CaV1.2-Ahnak complex. 相似文献
19.
Three types of transgenic tobacco plants were acquired by separate transformation or co-transformation of a vacuolar Na+/H+ antiporter gene, SeNHX1, and a betaine synthesis gene, BADH. When exposed to 200 mM NaCl, the dual gene-transformed plants displayed greater accumulation of betaine and Na+ than their wild-type counterparts. Photosynthetic rate and photosystem II activity in the transgenic plants were less affected
by salt stress than wild-type plants. Transgenic plants exhibited a greater increase in osmotic pressure than wild-type plants
when exposed to NaCl. More importantly, the dual gene transformed plants accumulated higher biomass than either of the single
transgenic plants under salt stress. Taken together, these findings indicate that simultaneous transformation of BADH and SeNHX1 genes into tobacco plants can enable plants to accumulate betaine and Na+, thus conferring them more tolerance to salinity than either of the single gene transformed plants or wild-type tobacco plants.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
A ouabain sensitive inward current occurs in Xenopus oocytes in Na+ and K+ -free solutions. Several laboratories have investigated the properties of this current and suggested that acidic extracellular pH (pHo) produces a conducting pathway through the Na+/K+ pump that is permeable to H+ and blocked by [Na+]o. An alternative suggestion is that the current is mediated by an electrogenic H+-ATPase. Here we investigate the effect of pHo and [Na+]o on both transient and steady-state ouabain-sensitive current. At alkaline or neutral pHo the relaxation rate of pre-steady-state current is an exponential function of voltage. Its U-shaped voltage dependence becomes apparent at acidic pHo, as predicted by a model in which protonation of the Na+/K+ pump reduces the energy barrier between the internal solution and the Na+ occluded state. The model also predicts that acidic pHo increases steady-state current leak through the pump. The apparent pK of the titratable group(s) is 6, suggesting that histidine is involved in induction of the conductance pathway. 22Na efflux experiments in squid giant axon and current measurements in oocytes at acidic pHo suggest that both Na+ and H+ are permeant. The acid-induced inward current is reduced by high [Na+]o, consistent with block by Na+. A least squares analysis predicts that H+ is four orders of magnitude more permeant than Na+, and that block occurs when 3 Na+ ions occupy a low affinity binding site (K
0.5=130±30 mM) with a dielectric coefficient of 0.23±0.03. These data support the conclusion that the ouabain-sensitive conducting pathway is a result of passive leak of both Na+ and H+ through the Na+/K+ pump. 相似文献