共查询到20条相似文献,搜索用时 31 毫秒
1.
S. Walsh C.J. Haddad M.A. Kostek T.J. Angelopoulos P.M. Clarkson P.M. Gordon N.M. Moyna P.S. Visich R.F. Zoeller R.L. Seip S. Bilbie P.D. Thompson J. Devaney H. Gordish-Dressman E.P. Hoffman Thomas B. Price L.S. Pescatello 《Gene》2012
Purpose
We investigated the influence of Leptin (LEP) and leptin receptor (LEPR) SNPs on habitual physical activity (PA) and body composition response to a unilateral, upper body resistance training (RT) program.Methods
European-derived American volunteers (men = 111, women = 131, 23.4 ± 5.4 yr, 24.4 ± 4.6 kg·m− 2) were genotyped for LEP 19 G>A (rs2167270), and LEPR 326 A>G (rs1137100), 668 A>G (rs1137101), 3057 G>A (rs1805096), and 1968 G>C (rs8179183). They completed the Paffenbarger PA Questionnaire. Arm muscle and subcutaneous fat volumes were measured before and after 12 wk of supervised RT with MRI. Multivariate and repeated measures ANCOVA tested differences among phenotypes by genotype and gender with age and body mass index as covariates.Results
Adults with the LEP 19 GG genotype reported more kcal/wk in vigorous intensity PA (1273.3 ± 176.8, p = 0.017) and sports/recreation (1922.8 ± 226.0, p < 0.04) than A allele carriers (718.0 ± 147.2, 1328.6 ± 188.2, respectively). Those with the LEP 19 GG genotype spent more h/wk in light intensity PA (39.7 ± 1.6) than A allele carriers (35.0 ± 1.4, p = 0.03). In response to RT, adults with the LEPR 668 G allele gained greater arm muscle volume (67,687.05 ± 3186.7 vs. 52,321.87 ± 5125.05 mm3, p = 0.01) and subcutaneous fat volume (10,599.89 ± 3683.57 vs. − 5224.73 ± 5923.98 mm3, p = 0.02) than adults with the LEPR 668 AA genotype, respectively.Conclusion
LEP19 G>A and LEPR 668 A>G associated with habitual PA and the body composition response to RT. These LEP and LEPR SNPs are located in coding exons likely influencing LEP and LEPR function. Further investigation is needed to confirm our findings and establish mechanisms for LEP and LEPR genotype and PA and body composition associations we observed. 相似文献2.
María C. Castro Flavio Francini Juan J. Gagliardino María L. Massa 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
Fructose administration rapidly induces oxidative stress that triggers compensatory hepatic metabolic changes. We evaluated the effect of an antioxidant, R/S-α-lipoic acid on fructose-induced oxidative stress and carbohydrate metabolism changes.Methods
Wistar rats were fed a standard commercial diet, the same diet plus 10% fructose in drinking water, or injected with R/S-α-lipoic acid (35 mg/kg, i.p.) (control + L and fructose + L). Three weeks thereafter, blood samples were drawn to measure glucose, triglycerides, insulin, and the homeostasis model assessment-insulin resistance (HOMA-IR) and Matsuda indices. In the liver, we measured gene expression, protein content and activity of several enzymes, and metabolite concentration.Results
Comparable body weight changes and calorie intake were recorded in all groups after the treatments. Fructose fed rats had hyperinsulinemia, hypertriglyceridemia, higher HOMA-IR and lower Matsuda indices compared to control animals. Fructose fed rats showed increased fructokinase gene expression, protein content and activity, glucokinase and glucose-6-phosphatase gene expression and activity, glycogen storage, glucose-6-phosphate dehydrogenase mRNA and enzyme activity, NAD(P)H oxidase subunits (gp91phox and p22phox) gene expression and protein concentration and phosphofructokinase-2 protein content than control rats. All these changes were prevented by R/S-α-lipoic acid co-administration.Conclusions
Fructose induces hepatic metabolic changes that presumably begin with increased fructose phosphorylation by fructokinase, followed by adaptive changes that attempt to switch the substrate flow from mitochondrial metabolism to energy storage. These changes can be effectively prevented by R/S-α-lipoic acid co-administration.General significance
Control of oxidative stress could be a useful strategy to prevent the transition from impaired glucose tolerance to type 2 diabetes. 相似文献3.
Aims
Dietary flavonoid intake shows a significant inverse association with mortality from coronary heart disease, incidence of myocardial infarction and stroke. Quercetin is one of the most common flavonoids in our diet and has several favorable biological activities. Quercetin glucosides, which are enzymatically trans-glycosylated isoquercitrin, have high water-solubility and bioavailability compared with quercetin. Here, we investigated the effects of quercetin glucosides on collateral development in a murine hindlimb ischemia model.Main methods
We induced hindlimb ischemia in 24- to 32-week-old male C3H/HeJ mice by resecting the right femoral artery. Then, 0.5% carboxymethyl cellulose (control) or quercetin glucosides (100 mg/kg/day) were administered daily by gavage. Blood flow was monitored weekly by laser Doppler imaging.Key findings
Recovery of blood flow to the ischemic leg was significantly enhanced by quercetin glucosides (blood flow ratio at 4 weeks: control, 0.57 ± 0.11; quercetin glucosides, 0.95 ± 0.10, p < 0.05). Furthermore, anti-CD31 immunostaining revealed that quercetin glucosides increased capillary density in the ischemic muscle (control, 200 ± 24/mm2; quercetin glucosides, 364 ± 41/mm2, p < 0.01). Quercetin glucosides did not promote tumor growth. The beneficial effect of quercetin glucosides was abrogated in eNOS-deficient mice.Significance
These results suggest that quercetin glucosides may have therapeutic potential to promote angiogenesis in ischemic tissue. 相似文献4.
5.
Carrie A. May John K. Grady Thomas M. Laue Maura Poli Paolo Arosio N. Dennis Chasteen 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Background
Ferritin exhibits complex behavior in the ultracentrifuge due to variability in iron core size among molecules. A comprehensive study was undertaken to develop procedures for obtaining more uniform cores and assessing their homogeneity.Methods
Analytical ultracentrifugation was used to measure the mineral core size distributions obtained by adding iron under high- and low-flux conditions to horse spleen (apoHoSF) and human H-chain (apoHuHF) apoferritins.Results
More uniform core sizes are obtained with the homopolymer human H-chain ferritin than with the heteropolymer horse spleen HoSF protein in which subpopulations of HoSF molecules with varying iron content are observed. A binomial probability distribution of H- and L-subunits among protein shells qualitatively accounts for the observed subpopulations. The addition of Fe2+ to apoHuHF produces iron core particle size diameters from 3.8 ± 0.3 to 6.2 ± 0.3 nm. Diameters from 3.4 ± 0.6 to 6.5 ± 0.6 nm are obtained with natural HoSF after sucrose gradient fractionation. The change in the sedimentation coefficient as iron accumulates in ferritin suggests that the protein shell contracts ∼ 10% to a more compact structure, a finding consistent with published electron micrographs. The physicochemical parameters for apoHoSF (15%/85% H/L subunits) are M = 484,120 g/mol, ν? = 0.735 mL/g, s20,w = 17.0 S and D20,w = 3.21 × 10−7 cm2/s; and for apoHuHF M = 506,266 g/mol, ν? = 0.724 mL/g, s20,w = 18.3 S and D20,w = 3.18 × 10−7 cm2/s.Significance
The methods presented here should prove useful in the synthesis of size controlled nanoparticles of other minerals. 相似文献6.
Kenjiro Tanaka Takahiro Shimizu Youichirou Higashi Kumiko Nakamura Keisuke Taniuchi Fotios Dimitriadis Shogo Shimizu Kunihiko Yokotani Motoaki Saito 《Life sciences》2014
Aims
Cyclooxygenase (COX) can be activated by nitric oxide-induced (NO-induced) conversion of cysteine thiol group of COX into S-nitrosothiol. We previously reported the involvement of brain COX/NO synthase (NOS) in centrally administered bombesin-, a stress-related neuropeptide, induced secretion of rat adrenal noradrenaline and adrenaline. To examine a possible involvement of the NO-induced modification of COX in bombesin-induced response, we investigated whether bombesin induces close proximity of COX-1 and neuronal NOS (nNOS) or S-nitroso-cysteine in pre-sympathetic spinally projecting neurons in the rat hypothalamic paraventricular nucleus (PVN), a regulatory center of adrenomedullary outflow.Main methods
In twelve-week-old male Wistar rats, pre-sympathetic spinally projecting neurons in the PVN were labeled with a retrograde tracer Fluoro-Gold (FG). After intracerebroventricular administration of bombesin, we performed double immunohistochemical analysis for Fos and COX-1 or nNOS in FG-labeled PVN neurons. We also performed a fluorescent in situ proximity ligation assay (PLA) for visualizing of close proximity (< 40 nm) of COX-1 with nNOS or S-nitroso-cysteine.Key. findings
Bombesin significantly increased the number of Fos-immunoreactive cells in FG-labeled PVN neurons with COX-1 or nNOS immunoreactivity. 7-Nitroindazole, a selective nNOS inhibitor, abolished Fos-immunoreactivity induced by bombesin in COX-1-immunoreactive FG-labeled PVN neurons. Bombesin also induced PLA-positive signals indicating close proximity of COX-1/nNOS and COX-1/S-nitroso-cysteine in FG-labeled PVN neurons.Significance
Centrally administered bombesin possibly induces S-nitrosylation of COX-1 through close proximity of COX-1 and nNOS in pre-sympathetic spinally projecting PVN neurons, thereby activating COX-1 during the bombesin-induced activation of central adrenomedullary outflow in the rat. 相似文献7.
Harmanpreet Kaur Rebecca Heeney Rupp Carriveau Gabriel Sosne Bulent Mutus 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Background
Thymosin beta 4 (Tβ4) is a major actin sequestering peptide present in most mammalian cells. It also acts as an anti-inflammatory agent and promotes corneal wound healing.Methods
In the present study, we constructed a four channel cylindrical flow chambers out of polydimethylsiloxane (PDMS) on microscope coverslips. The platelet-binding proteins–fibrinogen and collagen–were immobilized onto the middle ~ 25% of the inner cylindrical surface. The flow method introduced here was employed to determine the effect of Tβ4, on the deposition of ADP-activated platelets onto fibrinogen cross-linked flow chambers.Results
The binding data from the flow chambers indicated that the both the rate constant of platelet deposition (average: 0.026 ± 0.0015 s− 1, corresponding to a half-life of 26.7 s) and the total number of deposited platelets were independent of the platelet binding protein and the activating agent. Our results show that low concentrations of Tβ4 (0.2 μM to 0.5 μM) increased both the rate constant of platelet deposition by ~ 1.5-fold (i.e. half-life decreased from 26.7 s to 17.6 s) and the total number of deposited platelets by ~ 3-fold. However at higher concentrations (> 1 μM) the Tβ4-potentiating effect was diminished to near control levels. Tβ4 did interact with fibrinogen with an estimated KD of ~ 126 ± 18 nM or 66 ± 20 nM under equilibrium or flow, respectively.Conclusion
These results suggest that Tβ4 could potentially increase the affinity of platelet receptors for their ligands thus promoting platelet deposition. Tβ4 could also bind to fibrinogen and as its concentration increased would prevent platelet–fibrinogen interactions resulting in the attenuation of platelet deposition.General significance
This work suggests that Tβ4 might have a dual role in platelet function. 相似文献8.
Wutao Zeng Jian gui He Hong Ma 《Biochemical and biophysical research communications》2009,389(1):138-1412
Objective
Angiotensin-(1-7) [ANG-(1-7)] has been reported to attenuate neointimal formation after vascular injury and stent implantation in rats, but the mechanism remains mostly unresolved. Interestingly, the levels of circulating transforming growth factor-beta1 (TGF-β1) after myocardial infarction were suppressed by ANG-(1-7), which suggests a possible downstream target for the anti-remodeling action of ANG-(1-7). Our study focused on the effects of ANG-(1-7) on vascular remodeling, including neointimal formation and collagen synthesis, and determining whether or not these effects were dependent upon the TGF-β signaling pathway.Methods
Thirty-two New Zealand white rabbits underwent sham surgery or angioplasty in abdominal aorta. The animals were divided into four groups, which were sham, control, ANG-(1-7), and ANG-(1-7) + A-779. Subsequently, an osmotic minipump was implanted to deliver saline, ANG-(1-7) (576 μg kg−1 d−1) or ANG-(1-7) + A-779 (576 μg kg−1 d−1) for 4 weeks.Results
The ANG-(1-7) group displayed a significant reduction in neointimal thickness (207.51 ± 16.70 μm vs. 448.08 ± 15.30 μm, P < 0.001), neointimal area (0.266 ± 0.009 mm2 vs. 0.408 ± 0.002 mm2, P < 0.001), and restenosis rate (28.13 ± 2.74% vs. 40.13 ± 2.74%, P < 0.001) when compared to the control group. ANG-(1-7) also inhibited collagen synthesis by significantly decreasing the mRNA expression of Collagen I and Collagen III (vs. Control group: 0.2190 ± 0.0036 vs. 0.3852 ± 0.0212, P < 0.001 and 1.1328 ± 0.0554 vs. 1.7378 ± 0.1164, P < 0.001, respectively). Furthermore, the expression of TGF-β1 and phosphor-Smad2 (p-Smad2) were significantly suppressed by ANG-(1-7) (vs. Control group: 1.21 ± 0.07 vs. 1.54 ± 0.08, P < 0.001 and 0.31 ± 0.01 vs. 0.43 ± 0.02, P < 0.001, respectively), but no effect on p38 phosphorylation was observed. [d-Ala7]-ANG-(1-7) (A-779), showed a tendency to attenuate the anti-remodeling effects of ANG-(1-7).Conclusion
ANG-(1-7) decreases the amount of vascular remodeling, including a reduction in neointimal formation and collagen synthesis, after angioplasty in rabbits. The responsible mechanism may function through the possible down-regulation of TGF-β1 levels and inhibition of the Smad2 pathway. 相似文献9.
Aims
Aristolochic acid (AA) nephrotoxicity is related to accumulation of methylglyoxal (MGO) and Nε-(carboxymethyl)lysine (CML) in the mouse kidney. We studied the activity of renal semicarbazide-sensitive amine oxidase (SSAO), a key enzyme involved in MGO generation, in AA-treated mice, and investigated nephroprotective effects produced by metformin, a MGO scavenger.Methods
Mice were orally administered water or metformin for 15 days (12 or 24 mg kg− 1 day− 1), and injected AA (5 mg kg− 1 day− 1) intraperitoneally for 8 days starting on day 8. Renal function was studied, and histopathological examination, determination of renal SSAO activity, and measurement of MGO levels were performed.Key findings
Compared to control mice, AA-injected mice showed significant renal damage and approximately 2.7-fold greater renal SSAO activity (p < 0.05). Further, compared to control treatment, administration of 12 mg/kg metformin inhibited formation of renal lesions, and significantly decreased renal MGO levels (37.33 ± 9.78 vs. 5.89 ± 2.64 μg/mg of protein, respectively, p < 0.01). In the AA-treated mice, metformin also inhibited the accumulation of CML in renal tubules, but did not affect SSAO activity.Significance
This study is the first to show elevated renal SSAO activity in AA-treated mice, which could be involved in MGO accumulation. Moreover, MGO scavenging by metformin reduces AA nephrotoxicity. These findings suggest that reducing MGO accumulation produces nephroprotection, revealing new therapeutic strategies for the management. SSAO is a key enzyme involved in MGO generation, and consequently, inhibition of renal SSAO activity is worth investigating in AA nephrotoxicity and other renal pathologies further. 相似文献10.
Jaqueline Soares da Silva Sharlene Lopes Pereira Rodolfo do Couto Maia Sharon Schilling Landgraf Celso Caruso-Neves Arthur Eugen Kümmerle Carlos Alberto Manssour Fraga Eliezer Jesus Barreiro Roberto Takashi Sudo Gisele Zapata-Sudo 《Life sciences》2014
Aims
This work investigated the effects of 3,4-methylenedioxybenzoyl-2-thienylhydrazone (LASSBio-294) treatment on the contractile response of soleus (SOL) muscle from rats submitted to myocardial infarction (MI).Main methods
Following coronary artery ligation, LASSBio-294 (2 mg/kg, i.p.) or vehicle was administrated once daily for 4 weeks.Key findings
The run time to fatigue for sham rats was 17.9 ± 2.6 min, and it was reduced to 3.3 ± 0.8 min (P < 0.05) in MI rats. In MI rats treated with LASSBio-294, the time to fatigue was 15.1 ± 3.6 min. During the contractile test, SOL muscles from sham rats showed a response of 7.12 ± 0.54 N/cm2 at 60 Hz, which was decreased to 5.45 ± 0.49 N/cm2 (P < 0.05) in MI rats. The contractility of SOL muscles from the MI-LASSBio-294 group was increased to 9.01 ± 0.65 N/cm2. At 16 mM caffeine, the contractility was reduced from 2.31 ± 0.33 to 1.60 ± 0.21 N/cm2 (P < 0.05) in the MI group. In SOL muscles from MI-LASSBio-294 rats, the caffeine response was increased to 2.62 ± 0.33 N/cm2. Moreover, SERCA2a expression in SOL muscles was decreased by 0.31-fold (31%) in the MI group compared to the Sham group (P < 0.05). In the MI-LASSBio-294 group, it was increased by 1.53-fold (153%) compared to the MI group (P < 0.05). Meanwhile, the nuclear density in SOL muscles was increased in the MI group compared to the Sham group. Treatment with LASSBio-294 prevented this enhancement of cellular infiltrate.Significance
LASSBio-294 treatment prevented the development of muscular fatigue and improved exercise intolerance in rats submitted to MI. 相似文献11.
Jessica A.M. Bastiaansen Tian Cheng Mor Mishkovsky João M.N. Duarte Arnaud Comment Rolf Gruetter 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Acetate metabolism in skeletal muscle is regulated by acetylCoA synthetase (ACS). The main function of ACS is to provide cells with acetylCoA, a key molecule for numerous metabolic pathways including fatty acid and cholesterol synthesis and the Krebs cycle.Methods
Hyperpolarized [1-13C]acetate prepared via dissolution dynamic nuclear polarization was injected intravenously at different concentrations into rats. The 13C magnetic resonance signals of [1-13C]acetate and [1-13C]acetylcarnitine were recorded in vivo for 1 min. The kinetic rate constants related to the transformation of acetate into acetylcarnitine were deduced from the 3 s time resolution measurements using two approaches, either mathematical modeling or relative metabolite ratios.Results
Although separated by two biochemical transformations, a kinetic analysis of the 13C label flow from [1-13C]acetate to [1-13C]acetylcarnitine led to a unique determination of the activity of ACS. The in vivo Michaelis constants for ACS were KM = 0.35 ± 0.13 mM and Vmax = 0.199 ± 0.031 μmol/g/min.Conclusions
The conversion rates from hyperpolarized acetate into acetylcarnitine were quantified in vivo and, although separated by two enzymatic reactions, these rates uniquely defined the activity of ACS. The conversion rates associated with ACS were obtained using two analytical approaches, both methods yielding similar results.General significance
This study demonstrates the feasibility of directly measuring ACS activity in vivo and, since the activity of ACS can be affected by various pathological states such as cancer or diabetes, the proposed method could be used to non-invasively probe metabolic signatures of ACS in diseased tissue. 相似文献12.
M.C. Ribeiro M.S. Costa-Alves M. Wengert J.R. Meyer-Fernandes P. Zancan C. Caruso-Neves A.A.S. Pinheiro 《Biochimica et Biophysica Acta (BBA)/General Subjects》2012
Background
The concentration of extracellular nucleotides is regulated by enzymes that have their catalytic site facing the extracellular space, the so-called ecto-enzymes.Methods
We used LLC-PK1 cells, a well-characterized porcine renal proximal tubule cell line, to biochemically characterize ecto-ATPase activity in the luminal surface. The [γ-32P]Pi released after reaction was measured in aliquots of the supernatant by liquid scintillation.Results
This activity was linear with time up to 20 min of reaction and stimulated by divalent metals. The ecto-ATPase activity measured in the presence of 5 mM MgCl2 was (1) optimum at pH 8, (2) insensitive to different inhibitors of intracellular ATPases, (3) inhibited by 1 mM suramin, an inhibitor of ecto-ATPases, (4) sensitive to high concentrations of sodium azide (NaN3) and (5) also able to hydrolyze ADP in the extracellular medium. The ATP:ADP hydrolysis ratio calculated was 4:1. The ecto-ADPase activity was also inhibited by suramin and NaN3. The dose–response of ATP revealed a hyperbolic profile with maximal velocity of 25.2 ± 1.2 nmol Pi x mg− 1 x min− 1 and K0.5 of 0.07 ± 0.01 mM. When cells were submitted to ischemia, the E-NTPDase activity was reduced with time, achieving 71% inhibition at 60 min of ischemia.Conclusion
Our results suggest that the ecto-ATPase activity of LLC-PK1 cells has the characteristics of a type 3 E-NTPDase which is inhibited by ischemia.General Significance
This could represent an important pathophysiologic mechanism that explains the increase in ATP concentration in the extracellular milieu in the proximal tubule during ischemia. 相似文献13.
T. Marchini N. Magnani V. D'Annunzio D. Tasat R.J. Gelpi S. Alvarez P. Evelson 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
It has been suggested that mitochondrial function plays a central role in cardiovascular diseases associated with particulate matter inhalation. The aim of this study was to evaluate this hypothesis, with focus on cardiac O2 and energetic metabolism, and its impact over cardiac contractility.Methods
Swiss mice were intranasally instilled with either residual oil fly ash (ROFA) (1.0 mg/kg body weight) or saline solution. After 1, 3 or 5 h of exposure, O2 consumption was evaluated in heart tissue samples. Mitochondrial respiration, respiratory chain complexes activity, membrane potential and ATP content and production rate were assessed in isolated mitochondria. Cardiac contractile reserve was evaluated according to the Langendorff technique.Results
Three hours after ROFA exposure, tissue O2 consumption was significantly decreased by 35% (from 1180 ± 70 to 760 ± 60 ng-at O/min g tissue), as well as mitochondrial rest (state 4) and active (state 3) respiration, by 30 and 24%, respectively (control state 4: 88 ± 5 ng-at O/min mg protein; state 3: 240 ± 20 ng-at O/min mg protein). These findings were associated with decreased complex II activity, mitochondrial depolarization and deficient ATP production. Even though basal contractility was not modified (control: 75 ± 5 mm Hg), isolated perfused hearts failed to properly respond to isoproterenol in ROFA-exposed mice. Tissue O2 consumption rates positively correlated with cardiac contractile state in controls (r2 = 0.8271), but not in treated mice (r2 = 0.1396).General Significance
The present results show an impaired mitochondrial function associated with deficient cardiac contractility, which could represent an early cardiovascular alteration after the exposure to environmental particulate matter. 相似文献14.
Seham Mustafa Abdelhamid Elgazzar Mousa Khadadah Maryam Al Hussaini 《Journal of thermal biology》2013
Background/Aim
The Respiratory system can be affected by exposure to cold. It is well known that acute cold exposure induces asthmatic attacks. However, the influence of chronic cold environment exposure on lung perfusion and the pulmonary circulation was not studied in any previous study. Therefore this study was designed to investigates the effects of chronic cold exposure on lung perfusion using radionuclide study.Methods
New Zealand White rabbits were used in these experiments. The rabbits were kept in the cold room (4 °C) for 7 weeks. Lung perfusion scintigraphy was performed at the end of this period. Each rabbit was injected with 74 MBq (2 mCi) technetium-99m macroaggregated of albumin (99mTc MAA). Perfusion studies were done using Gamma camera equipped with a low energy, high resolution, parallel hole collimator interfaced with a computer. Static images were obtained 5 min after administration of the radiotracer. Static images were acquired include anterior/posterior (Ant/Post), right anterior oblique/left posterior oblique (RAO/LPO), right lateral/left lateral (RLat/LLat), right posterior oblique/left anterior oblique (RPO/LAO).Results
Rabbits chronically exposed to cold had lesser lung perfusion than controls using radionuclide perfusion study. The lung counts of chronic cold exposure (4 °C) for 7 weeks on rabbit lung perfusion for 5 min was 64±4%. (n=6, ???P<0.001).Conclusions
Our results indicate that chronic cold exposure decreased pulmonary circulation and lung perfusion in normal subjects. Therefore chronic cold exposure might worsen some diseases that are affected by cold such as asthma. 相似文献15.
Santosh Kumar Sahu Gopala Krishna Aradhyam Sathyanarayana N. Gummadi 《Biochimica et Biophysica Acta (BBA)/General Subjects》2009
Background
Phospholipid scramblases are a group of four homologous proteins conserved from C. elegans to human. In human, two members of the scramblase family, hPLSCR1 and hPLSCR3 are known to bring about Ca2+ dependent translocation of phosphatidylserine and cardiolipin respectively during apoptotic processes. However, affinities of Ca2+/Mg2+ binding to human scramblases and conformational changes taking place in them remains unknown.Methods
In the present study, we analyzed the Ca2+ and Mg2+ binding to the calcium binding motifs of hPLSCR1–4 and hPLSCR1 by spectroscopic methods and isothermal titration calorimetry.Results
The results in this study show that (i) affinities of the peptides are in the order hPLSCR1 > hPLSCR3 > hPLSCR2 > hPLSCR4 for Ca2+ and in the order hPLSCR1 > hPLSCR2 > hPLSCR3 > hPLSCR4 for Mg2+, (ii) binding of ions brings about conformational change in the secondary structure of the peptides. The affinity of Ca2+ and Mg2+ binding to protein hPLSCR1 was similar to that of the peptide I. A sequence comparison shows the existence of scramblase-like motifs among other protein families.Conclusions
Based on the above results, we hypothesize that the Ca2+ binding motif of hPLSCR1 is a novel type of Ca2+ binding motif.General significance
Our findings will be relevant in understanding the calcium dependent scrambling activity of hPLSCRs and their biological function. 相似文献16.
17.
Background
Malaria is a devastating disease and Plasmodium falciparum is the most lethal parasite infecting humans. Understanding the biology of this parasite is vital in identifying potential novel drug targets. During every 48-hour intra-erythrocytic asexual replication cycle, a single parasite can produce up to 32 progeny. This extensive proliferation implies that parasites require substantial amounts of lipid precursors for membrane biogenesis. Glycerol kinase is a highly conserved enzyme that functions at the interface of lipid synthesis and carbohydrate metabolism. P. falciparum glycerol kinase catalyzes the ATP-dependent phosphorylation of glycerol to glycerol-3-phosphate, a major phospholipid precursor.Methods
The P. falciparum glycerol kinase gene was disrupted using double crossover homologous DNA recombination to generate a knockout parasite line. Southern hybridization and mRNA analysis were used to verify gene disruption. Parasite growth rates were monitored by flow cytometry. Radiolabelling studies were used to assess incorporation of glycerol into parasite phospholipids.Results
Disruption of the P. falciparum glycerol kinase gene produced viable parasites, but their growth was significantly reduced to 56.5 ± 1.8% when compared to wild type parasites. 14C-glycerol incorporation into the major phospholipids of the parasite membrane, phosphatidylcholine and phosphatidylethanolamine, was 48.4 ± 10.8% and 53.1 ± 5.7% relative to an equivalent number of wild type parasites.Conclusions
P. falciparum glycerol kinase is required for optimal intra-erythrocytic asexual parasite development. Exogenous glycerol may be used as an alternative carbon source for P. falciparum phospholipid biogenesis, despite the lack of glycerol kinase to generate glycerol-3-phosphate.General significance
These studies provide new insight into glycerolipid metabolism in P. falciparum. 相似文献18.
Thanutchaporn Kumrungsee Tomomi SaikiSayaka Akiyama Kentaro NakashimaMitsuru Tanaka Yutaro KobayashiToshiro Matsui 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
Tryptophan-histidine (Trp-His) was found to suppress the activity of the Ca2 +/calmodulin (CaM)-dependent protein kinases II (CaMKII), which requires the Ca2 +-CaM complex for an initial activation. In this study, we attempted to clarify whether Trp-His inhibits Ca2 +-CaM complex formation, a CaMKII activator.Methods
The ability of Trp-His and other peptides to inhibit Ca2 +-CaM complex formation was investigated by a Ca2 +-encapsulation fluorescence assay. The peptide-CaM interactions were illustrated by molecular dynamic simulation.Results
We showed that Trp-His inhibited Ca2 +-CaM complex formation with a 1:1 binding stoichiometry of the peptide to CaM, considering that Trp-His reduced Hill coefficient of Ca2 +-CaM binding from 2.81 to 1.92. His-Trp also showed inhibitory activity, whereas Trp + His, 3-methyl His-Trp, and Phe-His did not show significant inhibitory activity, suggesting that the inhibitory activity was due to a peptide skeleton (irrespective of the sequence), a basic amino acid, a His residue, the N hydrogen atom of its imidazole ring, and Trp residue. In silico studies suggested the possibility that Trp-His and His-Trp interacted with the Ca2 +-binding site of CaM by forming hydrogen bonds with key Ca2 +-binding residues of CaM, with a binding free energy of − 49.1 and − 68.0 kJ/mol, respectively.Conclusions
This is the first study demonstrating that the vasoactive dipeptide Trp-His possesses inhibitory activity against Ca2 +-CaM complex formation, which may elucidate how Trp-His inhibited CaMKII in a previous study.General significance
The results provide a basic idea that could lead to the development of small peptides binding with high affinity to CaM and inhibiting Ca2 +-CaM complex formation in the future. 相似文献19.
Li-Chen Ge Zhuo-Jia Chen Hao Liu Kun-Shui Zhang Qiao Su Xiang-Yu Ma Hong-Bin Huang Zhen-Dong Zhao Yu-Ye Wang John P. Giesy Jun Du Hong-Sheng Wang 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
Biphasic effects on cell proliferation of bisphenol A (BPA) can occur at lesser or greater exposures. Sertoli cells play a pivotal role in supporting proliferation and differentiation of germ cells. The mechanisms responsible for inverse effects of great and low concentrations of BPA on Sertoli cell proliferation need further study.Methods
We utilized proteomic study to indentify the protein expression changes of Sertoli TM4 cells treated with 10− 8 M and 10− 5 M BPA. The further mechanisms related to mitochondria, energy metabolism and oxidative stress were investigated by qRT-PCR and Western-blotting analysis.Results
Proteomic studies identified 36 proteins and two major clusters of proteins including energy metabolism and oxidative stress expressed with opposite changes in Sertoli cells treated with 10− 8 M and 10− 5 M BPA, respectively, for 24 h. Exposure to 10− 5 M BPA resulted in greater oxidative stress and then inhibited cell proliferation, while ROS scavenger NAC effectively blocked these effects. Exposure to 10− 8 M BPA caused higher intercellular ATP, greater activities of mitochondria, and resulted in significant proliferation of TM4 cells, while oligomycin A, an inhibitor of ATP synthase, abolished these growth advantages.Conclusions
Our study demonstrated that micromolar BPA inhibits proliferation of Sertoli cells by elevating oxidative stress while nanomolar BPA stimulates proliferation by promoting energy metabolism.General significance
Micromolar BPA inhibits cell proliferation by elevating oxidative stress while nanomolar BPA stimulates cell proliferation by promoting energy metabolism. 相似文献20.
Catalina Carrasco-Pozo Edgar Pastene Carola Vergara Moises Zapata Cristian Sandoval Martin Gotteland 《Biochimica et Biophysica Acta (BBA)/General Subjects》2012