Reverse mode Na+/Ca2+ exchange mediated by STIM1 contributes to Ca2+ influx in airway smooth muscle following agonist stimulation

<p>Abstract</p> <p>Background</p> <p>Agonist stimulation of airway smooth muscle (ASM) results in IP₃mediated Ca²⁺release from the sarcoplasmic reticulum followed by the activation of store operated and receptor operated non-selective cation channels. Activation of these non-selective channels also results in a Na⁺influx. This localised increase in Na⁺levels can potentially switch the Na⁺/Ca²⁺exchanger into reverse mode and so result in a further influx of Ca²⁺. The aim of this study was to characterise the expression and physiological function of the Na⁺/Ca²⁺exchanger in cultured human bronchial smooth muscle cells and determine its contribution to agonist induced Ca²⁺influx into these cells.</p> <p>Methods</p> <p>The expression profile of NCX (which encodes the Na⁺/Ca²⁺exchanger) homologues in cultured human bronchial smooth muscle cells was determined by reverse transcriptase PCR. The functional activity of reverse mode NCX was investigated using a combination of whole cell patch clamp, intracellular Ca²⁺measurements and porcine airway contractile analyses. KB-R7943 (an antagonist for reverse mode NCX) and target specific siRNA were utilised as tools to inhibit NCX function.</p> <p>Results</p> <p>NCX1 protein was detected in cultured human bronchial smooth muscle cells (HBSMC) cells and NCX1.3 was the only mRNA transcript variant detected. A combination of intracellular Na⁺loading and addition of extracellular Ca²⁺induced an outwardly rectifying current which was augmented following stimulation with histamine. This outwardly rectifying current was inhibited by 10 μM KB-R7943 (an antagonist of reverse mode NCX1) and was reduced in cells incubated with siRNA against NCX1. Interestingly, this outwardly rectifying current was also inhibited following knockdown of STIM1, suggesting for the first time a link between store operated cation entry and NCX1 activation. In addition, 10 μM KB-R7943 inhibited agonist induced changes in cytosolic Ca²⁺and induced relaxation of porcine peripheral airways.</p> <p>Conclusions</p> <p>Taken together, these data demonstrate a potentially important role for NCX1 in control of Ca²⁺homeostasis and link store depletion via STIM1 directly with NCX activation.</p

Modelling leaf photosynthetic and transpiration temperature-dependent responses in Vitis vinifera cv. Semillon grapevines growing in hot, irrigated vineyard conditions

Grapevines growing in Australia suffer from high temperatures which have major effects on photosynthesis and transpiration. To learn more, gas exchange was measured over several seasons and then modelled across temperatures from 20 to 45°C and validated with independent data

Anti-dsDNA Antibodies Promote Initiation, and Acquired Loss of Renal Dnase1 Promotes Progression of Lupus Nephritis in Autoimmune (NZBxNZW)F1 Mice

BACKGROUND:Lupus nephritis is characterized by deposition of chromatin fragment-IgG complexes in the mesangial matrix and glomerular basement membranes (GBM). The latter defines end-stage disease. METHODOLOGY/PRINCIPALS: In the present study we determined the impact of antibodies to dsDNA, renal Dnase1 and matrix metalloprotease (MMP) mRNA levels and enzyme activities on early and late events in murine lupus nephritis. The major focus was to analyse if these factors were interrelated, and if changes in their expression explain basic processes accounting for lupus nephritis. FINDINGS:Early phases of nephritis were associated with chromatin-IgG complex deposition in the mesangial matrix. A striking observation was that this event correlated with appearance of anti-dsDNA antibodies and mild or clinically silent nephritis. These events preceded down-regulation of renal Dnase1. Later, renal Dnase1 mRNA level and enzyme activity were reduced, while MMP2 mRNA level and enzyme activity increased. Reduced levels of renal Dnase1 were associated in time with deficient fragmentation of chromatin from dead cells. Large fragments were retained and accumulated in GBM. Also, since chromatin fragments are prone to stimulate Toll-like receptors in e.g. dendritic cells, this may in fact explain increased expression of MMPs. SIGNIFICANCE:These scenarios may explain the basis for deposition of chromatin-IgG complexes in glomeruli in early and late stages of nephritis, loss of glomerular integrity and finally renal failure

Endothelium Derived Nitric Oxide Synthase Negatively Regulates the PDGF-Survivin Pathway during Flow-Dependent Vascular Remodeling

Chronic alterations in blood flow initiate structural changes in vessel lumen caliber to normalize shear stress. The loss of endothelial derived nitric oxide synthase (eNOS) in mice promotes abnormal flow dependent vascular remodeling, thus uncoupling mechanotransduction from adaptive vascular remodeling. However, the mechanisms of how the loss of eNOS promotes abnormal remodeling are not known. Here we show that abnormal flow-dependent remodeling in eNOS knockout mice (eNOS (−/−)) is associated with activation of the platelet derived growth factor (PDGF) signaling pathway leading to the induction of the inhibitor of apoptosis, survivin. Interfering with PDGF signaling or survivin function corrects the abnormal remodeling seen in eNOS (−/−) mice. Moreover, nitric oxide (NO) negatively regulates PDGF driven survivin expression and cellular proliferation in cultured vascular smooth muscle cells. Collectively, our data suggests that eNOS negatively regulates the PDGF-survivin axis to maintain proportional flow-dependent luminal remodeling and vascular quiescence

The relation between schizotypy and early attention to rejecting interactions: The influence of neuroticism

© 2015 The Author(s). Published by Taylor & Francis. Objectives: Schizotypy relates to rejection sensitivity (anxiety reflecting an expectancy of social exclusion) and neuroticism (excessive evaluation of negative emotions). Positive schizotypy (e.g., perceptual aberrations and odd beliefs) and negative schizotypy (e.g., social and physical anhedonia) could relate to altered attention to rejection because of neuroticism. Methods: Forty-one healthy individuals were assessed on positive and negative schizotypy and neuroticism, and event-related potentials during rejecting, accepting and neutral scenes. Participants were categorised into high, moderate and low neuroticism groups. Using temporo-spatial principal components analyses, P200 (peak latency =290 ms) and P300 amplitudes (peak latency = 390 ms) were measured, reflecting mobilisation of attention and early attention, respectively. Results: Scalp-level and cortical source analysis revealed elevated fronto-parietal N300/P300 amplitude and P200-related dorsal anterior cingulate current density during rejection than acceptance/neutral scenes. Positive schizotypy related inversely to parietal P200 amplitude during rejection. Negative schizotypy related positively to P200 middle occipital current density. Negative schizotypy related positively to parietal P300, where the association was stronger in high and moderate, than low, neuroticism groups. Conclusions: Positive and negative schizotypy relate divergently to attention to rejection. Positive schizotypy attenuates, but negative schizotypy increases rejection-related mobilisation of attention. Negative schizotypy increases early attention to rejection partly due to elevated neuroticism

Caffeine Consumption Prevents Diabetes-Induced Memory Impairment and Synaptotoxicity in the Hippocampus of NONcZNO10/LTJ Mice

Diabetic conditions are associated with modified brain function, namely with cognitive deficits, through largely undetermined processes. More than understanding the underlying mechanism, it is important to devise novel strategies to alleviate diabetes-induced cognitive deficits. Caffeine (a mixed antagonist of adenosine A1 and A2A receptors) emerges as a promising candidate since caffeine consumption reduces the risk of diabetes and effectively prevents memory deficits caused by different noxious stimuli. Thus, we took advantage of a novel animal model of type 2 diabetes to investigate the behavioural, neurochemical and morphological modifications present in the hippocampus and tested if caffeine consumption might prevent these changes. We used a model closely mimicking the human type 2 diabetes condition, NONcNZO10/LtJ mice, which become diabetic at 7–11 months when kept under an 11% fat diet. Caffeine (1 g/l) was applied in the drinking water from 7 months onwards. Diabetic mice displayed a decreased spontaneous alternation in the Y-maze accompanied by a decreased density of nerve terminal markers (synaptophysin, SNAP25), mainly glutamatergic (vesicular glutamate transporters), and increased astrogliosis (GFAP immunoreactivity) compared to their wild type littermates kept under the same diet. Furthermore, diabetic mice displayed up-regulated A2A receptors and down-regulated A1 receptors in the hippocampus. Caffeine consumption restored memory performance and abrogated the diabetes-induced loss of nerve terminals and astrogliosis. These results provide the first evidence that type 2 diabetic mice display a loss of nerve terminal markers and astrogliosis, which is associated with memory impairment; furthermore, caffeine consumption prevents synaptic dysfunction and astrogliosis as well as memory impairment in type 2 diabetes

Elasticity, Stability and Ideal Strength of β\beta -SiC in plane-wave-based ab initio calculations

On the basis of the pseudopotential plane-wave(PP-PW) method and the local-density-functional theory(LDFT), this paper studies energetics, stress-strain relation, stability and ideal strength of $\beta$-SiC under various loading modes, where uniform uniaxial extension and tension, biaxial proportional extension are considered along directions [001] and [111]. The lattice constant, elastic constants and moduli of equilibrium state are calculated, and the results agree well with the experimental data. As the four Si-C bonds along directions [111], [$\bar{1}$11], [11$\bar{1}$] and [1$\bar{1}$1] are not the same under the loading along [111], internal relaxation and the corresponding internal displacements must be considered. We find that, at the beginning of loading, the effect of internal displacement through shuffle and glide plane diminishes the difference among the four Si-C bonds length, but will increase the difference at the subsequent loading, which will result in a crack nucleated on \{111\} shuffle plane and a subsequently cleavage fracture. Thus the corresponding theoretical strength is 50.8 GPa, which agrees well with the recent experiment value, 53.4 GPa. However, with the loading along [001], internal relaxation is not important for tetragonal symmetry. Elastic constants during the uniaxial tension along [001] are calculated. Based on the stability analysis with stiffness coefficients, we find that the spinodal and Born instabilities are triggered almost at the same strain, which agrees with the previous molecular dynamics simulation. During biaxial proportional extension, stress and strength vary proportionally with the biaxial loading ratio at the same longitudinal strain.Comment: 9 pages, 10 figure

Activation of cGMP-Dependent Protein Kinase Stimulates Cardiac ATP-Sensitive Potassium Channels via a ROS/Calmodulin/CaMKII Signaling Cascade

) channels, an ion channel critical for stress adaptation in the heart; however, the underlying mechanism remains largely unknown. The present study was designed to address this issue. channels was confirmed in intact ventricular cardiomyocytes, which was ROS- and CaMKII-dependent. Kinetically, PKG appeared to stimulate these channels by destabilizing the longest closed state while stabilizing the long open state and facilitating opening transitions. channels and contribute to cardiac protection against ischemia-reperfusion injury

Genome-wide association mapping identifies a new arsenate reductase enzyme critical for limiting arsenic accumulation in plants

Inorganic arsenic is a carcinogen, and its ingestion through foods such as rice presents a significant risk to human health. Plants chemically reduce arsenate to arsenite. Using genome-wide association (GWA) mapping of loci controlling natural variation in arsenic accumulation in Arabidopsis thaliana allowed us to identify the arsenate reductase required for this reduction, which we named High Arsenic Content 1 (HAC1). Complementation verified the identity of HAC1, and expression in Escherichia coli lacking a functional arsenate reductase confirmed the arsenate reductase activity of HAC1. The HAC1 protein accumulates in the epidermis, the outer cell layer of the root, and also in the pericycle cells surrounding the central vascular tissue. Plants lacking HAC1 lose their ability to efflux arsenite from roots, leading to both increased transport of arsenic into the central vascular tissue and on into the shoot. HAC1 therefore functions to reduce arsenate to arsenite in the outer cell layer of the root, facilitating efflux of arsenic as arsenite back into the soil to limit both its accumulation in the root and transport to the shoot. Arsenate reduction by HAC1 in the pericycle may play a role in limiting arsenic loading into the xylem. Loss of HAC1-encoded arsenic reduction leads to a significant increase in arsenic accumulation in shoots, causing an increased sensitivity to arsenate toxicity. We also confirmed the previous observation that the ACR2 arsenate reductase in A. thaliana plays no detectable role in arsenic metabolism. Furthermore, ACR2 does not interact epistatically with HAC1, since arsenic metabolism in the acr2 hac1 double mutant is disrupted in an identical manner to that described for the hac1 single mutant. Our identification of HAC1 and its associated natural variation provides an important new resource for the development of low arsenic-containing food such as rice