Lipid rafts and functional caveolae regulate HIV-induced amyloid beta accumulation in brain endothelial cells

Amyloid beta (Aβ) levels are increased in HIV-1 infected brains due to not yet fully understood mechanisms. In the present study, we investigate the role of lipid rafts, functional caveolae, and caveolae-associated signaling in HIV-1-induced Aβ accumulation in HBMEC. Both silencing of caveolin-1 (cav-1) and disruption of lipid rafts by pretreatment with beta-methyl-cyclodextrin (MCD) protected against Aβ accumulation in HBMEC. Exposure to HIV-1 and Aβ activated caveolae-associated Ras and p38. While inhibition of Ras by farnesylthiosalicylic acid (FTS) effectively protected against HIV-1-induced accumulation of Aβ, blocking of p38 did not have such an effect. We also evaluated the role of caveolae in HIV-1-induced upregulation of the receptor for advanced glycation end products (RAGE), which regulates Aβ transfer from the blood stream into the central nervous system. HIV-1-induced RAGE expression was prevented by infecting HBMEC with cav-1 specific shRNA lentiviral particles or by pretreatment of cells with FTS. Overall, the present results indicate that Aβ accumulation in HBMEC is lipid raft and caveolae dependent and involves the caveolae-associated Ras signaling.     

Internal motions and exchange processes in human ileal bile acid binding protein as studied by backbone (15)N nuclear magnetic resonance spectroscopy

Human ileal bile acid binding protein (I-BABP), a member of the family of intracellular lipid binding proteins, is thought to play a role in the enterohepatic circulation of bile salts. Previously, we have shown by stopped-flow fluorescence analysis that positive binding cooperativity exhibited by I-BABP in its interactions with glycocholate (GCA) and glycochenodeoxycholate (GCDA), the two primary bile salts in humans, is related to a slow conformational change in the protein. In this study, we used backbone (15)N relaxation nuclear magnetic resonance (NMR) techniques to obtain residue-specific information about the internal dynamics of apo I-BABP and the doubly ligated I-BABP:GCA:GCDA complex on various time scales. According to our NMR data, bile salt binding is accompanied by a slight rigidification of the (15)N-(1)H bond vectors on the picosecond to nanosecond time scale, with most pronounced changes occurring in the C-D region. In contrast to the minor effects of ligation on fast motions, relaxation dispersion NMR experiments indicate a marked difference between the two protein states on the microsecond to millisecond time scale. In the apo form, an extensive network of conformational fluctuations is detected throughout segments of the EFGHIJ β-strands and the C-D loop, which cease upon complexation. Our NMR data are in agreement with a conformational selection model we proposed earlier for I-BABP and support the hypothesis of an allosteric mechanism of ligand binding. According to the NMR measurements, the helical cap region may have a less crucial role in mediating ligand entry and release than what has been indicated for fatty acid binding proteins.     

Carotenoid composition and in vitro pharmacological activity of rose hips

The aim of the present study was to compare carotenoid extracts of Rose hips (Rosa canina L.) with regard to their phytochemical profiles and their in vitro anti-Helicobacter pylori (H. pylori), cytotoxic, multidrug resistance (MDR) reversal and radical scavenging activity. Carotenoid composition was investigated in the different fractionation of rose hips, using extraction methods. Six main carotenoids - epimers of neochrome, lutein, zeaxanthin, rubixanthin, lycopene, β,β-carotene - were identified from Rose hips by their chromatographic behavior and UV-visible spectra, which is in accordance with other studies on carotenoids in this plant material. The active principles in the carotenoid extract might differ, depending upon the extraction procedures.     

Geno viewer, a SAM/BAM viewer tool

The ever evolving Next Generation Sequencing technology is calling for new and innovative ways of data processing and visualization. Following a detailed survey of the current needs of researchers and service providers, the authors have developed GenoViewer: a highly user-friendly, easy-to-operate SAM/BAM viewer and aligner tool. GenoViewer enables fast and efficient NGS assembly browsing, analysis and read mapping. It is highly customized, making it suitable for a wide range of NGS related tasks. Due to its relatively simple architecture, it is easy to add specialised visualization functionalities, facilitating further customised data analysis. The software's source code is freely available; it is open for project and task-specific modifications. AVAILABILITY: The database is available for free at http://www.genoviewer.com/     

Treatment with insulin inhibits poly(ADP-ribose)polymerase activation in a rat model of endotoxemia

In critically ill patients various conditions may lead to the activation of poly(ADP-ribose) polymerase (PARP). By promoting cellular energetic dysfunction, and by enhancing pro-inflammatory gene expression, PARP activation significantly contributes to the pathogenesis of shock. PARP activation is usually triggered by DNA strand breakage, which is typically the result of the overproduction of various reactive oxidant species. One of the pathophysiological conditions associated with PARP activation is hyperglycemia, where the reactive species are produced from the mitochondria and other cellular sources. In the present study we tested whether endotoxin-induced PARP activation and pro-inflammatory mediator production can be modified by insulin therapy. Rats subjected to bacterial lipopolysaccharide (LPS) with or without insulin co-treatment were studied. LPS-induced PARP activation in circulating lymphocytes was measured by flow cytometry, tumor necrosis factor alpha (TNF-alpha) production was measured by ELISA. The direct effect of insulin on the PARP activity of mononuclear leukocytes and human umbilical vein endothelial cells (HUVEC) in elevated glucose conditions was tested in vitro. LPS-induced significant hyperglycemic response activated PARP in circulating lymphocytes and induced TNF-alpha production. Insulin treatment prevented LPS-induced hyperglycemic response, blocked PARP activation and blunted LPS-induced TNF-alpha response. Insulin treatment caused a slight reduction in the PARP activity of mononuclear cells and HUVECs in vitro. We demonstrate that insulin treatment blocks LPS-induced PARP activation in vivo. We propose that this effect is mainly indirect, and occurs due to the prevention of stress induced hyperglycemia, with a direct cellular effect of insulin playing a potential minor supplemental role. The current findings may have significant implications in the context of the emerging concept of tight glycemic control and insulin treatment for critically ill patients.     

A mutant small heat shock protein with increased thylakoid association provides an elevated resistance against UV-B damage in synechocystis 6803

Besides acting as molecular chaperones, the amphitropic small heat shock proteins (sHsps) are suggested to play an additional role in membrane quality control. We investigated sHsp membrane function in the model cyanobacterium Synechocystis sp. PPC 6803 using mutants of the single sHsp from this organism, Hsp17. We examined mutants in the N-terminal arm, L9P and Q16R, for altered interaction with thylakoid and lipid membranes and examined the effects of these mutations on thylakoid functions. These mutants are unusual in that they retain their oligomeric state and chaperone activity in vitro but fail to confer thermotolerance in vivo. We found that both mutant proteins had dramatically altered membrane/lipid interaction properties. Whereas L9P showed strongly reduced binding to thylakoid and model membranes, Q16R was almost exclusively membrane-associated, properties that may be the cause of reduced heat tolerance of cells carrying these mutations. Among the lipid classes tested, Q16R displayed the highest interaction with negatively charged SQDG. In Q16R cells a specific alteration of the thylakoid-embedded Photosystem II (PSII) complex was observed. Namely, the binding of plastoquinone and quinone analogue acceptors to the Q(B) site was modified. In addition, the presence of Q16R dramatically reduced UV-B damage of PSII activity because of enhanced PSII repair. We suggest these effects occur at least partly because of increased interaction of Q16R with SQDG in the PSII complex. Our findings further support the model that membrane association is a functional property of sHsps and suggest sHsps as a possible biotechnological tool to enhance UV protection of photosynthetic organisms.     

Accumulation of overproduced ferritin in the chloroplast provides protection against photoinhibition induced by low temperature in tobacco plants

Wild-type tobacco plants (Nicotiana tabacum L. cv. Petit Havanna line SR1) and plants transformed with full-length alfalfa ferritin cDNA with the chloroplast transit peptide under the control of a Rubisco small subunit gene promoter (C3 and C8) were cold-treated at 0 degrees C with continuous light (250mumolm(-2)s(-1)). These transgenic plants had higher chlorophyll content and higher F(v)/F(m) chlorophyll-a fluorescence induction parameters than wild-type plants after 2 or 3d of cold treatment in C3 and C8 transgenic plants, respectively. Thermoluminescence studies on the high-temperature bands suggest that these plants suffered less oxidative damage in comparison to the wild-type genotype. The present experiments provide evidence that transgenic tobacco lines overexpressing alfalfa ferritin, which is accumulated in the chloroplasts, may show higher tolerance to various stress factors, generating ROS including low temperature-induced photoinhibition.     

High-fat diet-induced obesity leads to increased NO sensitivity of rat coronary arterioles: role of soluble guanylate cyclase activation

The impact of obesity on nitric oxide (NO)-mediated coronary microvascular responses is poorly understood. Thus NO-mediated vasomotor responses were investigated in pressurized coronary arterioles ( approximately 100 microm) isolated from lean (on normal diet) and obese (fed with 60% of saturated fat) rats. We found that dilations to acetylcholine (ACh) were not significantly different in obese and lean rats (lean, 83 +/- 4%; and obese, 85 +/- 3% at 1 microM), yet the inhibition of NO synthesis with N(omega)-nitro-l-arginine methyl ester reduced ACh-induced dilations only in vessels of lean controls. The presence of the soluble guanylate cyclase (sGC) inhibitor oxadiazolo-quinoxaline (ODQ) elicited a similar reduction in ACh-induced dilations in the two groups of vessels (lean, 60 +/- 11%; and obese, 57 +/- 3%). Dilations to NO donors, sodium nitroprusside (SNP), and diethylenetriamine (DETA)-NONOate were enhanced in coronary arterioles of obese compared with lean control rats (lean, 63 +/- 6% and 51 +/- 5%; and obese, 78 +/- 5% and 70 +/- 5%, respectively, at 1 microM), whereas dilations to 8-bromo-cGMP were not different in the two groups. In the presence of ODQ, both SNP and DETA-NONOate-induced dilations were reduced to a similar level in lean and obese rats. Moreover, SNP-stimulated cGMP immunoreactivity in coronary arterioles and also cGMP levels in carotid arteries were enhanced in obese rats, whereas the protein expression of endothelial NOS and the sGC beta1-subunit were not different in the two groups. Collectively, these findings suggest that in coronary arterioles of obese rats, the increased activity of sGC leads to an enhanced sensitivity to NO, which may contribute to the maintenance of NO-mediated dilations and coronary perfusion in obesity.