Source and role of intestinally derived lysophosphatidic acid in dyslipidemia and atherosclerosis

We previously reported that i) a Western diet increased levels of unsaturated lysophosphatidic acid (LPA) in small intestine and plasma of LDL receptor null (LDLR^−/−) mice, and ii) supplementing standard mouse chow with unsaturated (but not saturated) LPA produced dyslipidemia and inflammation. Here we report that supplementing chow with unsaturated (but not saturated) LPA resulted in aortic atherosclerosis, which was ameliorated by adding transgenic 6F tomatoes. Supplementing chow with lysophosphatidylcholine (LysoPC) 18:1 (but not LysoPC 18:0) resulted in dyslipidemia similar to that seen on adding LPA 18:1 to chow. PF8380 (a specific inhibitor of autotaxin) significantly ameliorated the LysoPC 18:1-induced dyslipidemia. Supplementing chow with LysoPC 18:1 dramatically increased the levels of unsaturated LPA species in small intestine, liver, and plasma, and the increase was significantly ameliorated by PF8380 indicating that the conversion of LysoPC 18:1 to LPA 18:1 was autotaxin dependent. Adding LysoPC 18:0 to chow increased levels of LPA 18:0 in small intestine, liver, and plasma but was not altered by PF8380 indicating that conversion of LysoPC 18:0 to LPA 18:0 was autotaxin independent. We conclude that i) intestinally derived unsaturated (but not saturated) LPA can cause atherosclerosis in LDLR^−/− mice, and ii) autotaxin mediates the conversion of unsaturated (but not saturated) LysoPC to LPA.     

Isolated Diaphorase From Bovine Erythrocyte Cannot Reduce Oxidized Cytoglobin (Metcygb)

Background:Cytoglobin (Cygb) is a relatively newly identified globin protein that acts as an oxygen transporter in tissues like hemoglobin (Hb) in erythrocytes and myoglobin (Mb) in muscles. The natural oxidation of the Fe²⁺ ion in its heme group into metglobin (globin-Fe³⁺) made the loses of oxygen binding functions. It is known metHb and metMb can be reduced enzymatically using diaphorase or cyb5r3. However, metCygb reductase had not been previously identified. This study aims to analyze the reducing activity of bovine diaphorase on metCygb.Methods:Diaphorase was isolated from bovine erythrocyte and purified using gel filtration and cationic-exchanger chromatography. Its purity was verified by SDS-PAGE and western blot (WB). The metCygb was obtained from Cygb oxidation with potassium ferrocyanide and its reducing activity was determined by spectroscopy.Results:The diaphorase (MW=30.09 kDa) was purified 10.77-fold from crude enzyme with specific activity against metHb 8.479 U/mg. The purity was confirmed by WB using primary antibody anti-cyb5r3. The purified enzyme reduced metCygb at 0.785 µgmin^-1, which was 13.7 times less than the Vmax of metHb.DiscussionIn conclusion, the purified diaphorase from bovine erythrocytes did not significantly reduce metCygb rather than metHb, a natural substrate in cells.Key Words: Bovine Erythrocyte, Cytochrome B5 Reductase, Diaphorase, Metcytoglobin, Reduction     

Plasma Protein Profile of Lactating Women from Two Primary Health Centers in Jakarta,Indonesia

Background:Plasma protein profile test is a potential laboratory method to assess nutritional status especially albumin and globulins levels which reflects protein adequacy. The purpose of this study is to evaluate plasma protein profile of lactating women from two primary health centers in Jakarta.Methods:A cross-sectional study was conducted involving lactating women attending routine maternal examinations in two public primary health centers in Jakarta, Indonesia. The mother’s plasma total protein, albumin, globulin, and immunoglobulin levels were measured.Results:Sixty lactating women were recruited, mostly were 28 years old, slightly overweight, bearing two children, and their recent children were 2 months old. The mean total protein level was 8.13 g/dl, albumin 5.00 g/dl, globulin 3.18 g/dl, albumin: globulin ratio 1.558, mean total IgG level of 1255.98 and mean total IgM level of 135.819. All the measured plasma protein parameters were shown to be not correlated with maternal age, maternal BMI, or maternal parity.DiscussionThe plasma total protein, albumin, globulin, as well as total IgG and IgM level of lactating women in Jakarta were within normal range. These biochemical parameters were shown to be not correlated with anthropometrical data such as maternal age and BMI. The small and relatively homogenous samples were supposed to be the cause of such findings.Conclusion:The plasma protein profile of lactating women in Jakarta was adequate. Further studies are required to evaluate the eligibility of plasma protein profile as biochemical parameter of nutritional status in lactating women.Key Words: Blood protein, lactation, protein, albumin/globulin, immunoglobulin M/G     

A specific secretion system mediates PPE41 transport in pathogenic mycobacteria

Mycobacterial genomes contain two unique gene families, the so-called PE and PPE gene families, which are highly expanded in the pathogenic members of this genus. Here we report that one of the PPE proteins, i.e. PPE41, is secreted by pathogenic mycobacteria, both in culture and in infected macrophages. As PPE41 lacks a signal sequence a dedicated secretion system must be involved. A single gene was identified in Mycobacterium marinum that showed strongly reduced PPE41 secretion. This gene was located in a gene cluster whose predicted proteins encode components of an ESAT-6-like secretion system. This cluster, designated ESX-5, is conserved in various pathogenic mycobacteria, but not in the saprophytic species Mycobacterium smegmatis. Therefore, different regions of this cluster were introduced in M. smegmatis. Only introduction of the complete ESX-5 locus resulted in efficient secretion of heterologously expressed PPE41. This PPE secretion system is also involved in the virulence of pathogenic mycobacteria, as the ESX-5 mutant of M. marinum was affected in spreading to uninfected macrophages.     

DNase-chip: a high-resolution method to identify DNase I hypersensitive sites using tiled microarrays

Mapping DNase I hypersensitive sites is an accurate method of identifying the location of gene regulatory elements, including promoters, enhancers, silencers and locus control regions. Although Southern blots are the traditional method of identifying DNase I hypersensitive sites, the conventional manual method is not readily scalable to studying large chromosomal regions, much less the entire genome. Here we describe DNase-chip, an approach that can rapidly identify DNase I hypersensitive sites for any region of interest, or potentially for the entire genome, by using tiled microarrays. We used DNase-chip to identify DNase I hypersensitive sites accurately from a representative 1% of the human genome in both primary and immortalized cell types. We found that although most DNase I hypersensitive sites were present in both cell types studied, some of them were cell-type specific. This method can be applied globally or in a targeted fashion to any tissue from any species with a sequenced genome.     

Viral Entry Inhibitors Targeted to the Membrane Site of Action

The fusion of enveloped viruses with the host cell is driven by specialized fusion proteins to initiate infection. The “class I” fusion proteins harbor two regions, typically two heptad repeat (HR) domains, which are central to the complex conformational changes leading to fusion: the first heptad repeat (HRN) is adjacent to the fusion peptide, while the second (HRC) immediately precedes the transmembrane domain. Peptides derived from the HR regions can inhibit fusion, and one HR peptide, T20 (enfuvirtide), is in clinical use for HIV-1. For paramyxoviruses, the activities of two membrane proteins, the receptor-binding protein (hemagglutinin-neuraminidase [HN] or G) and the fusion protein (F), initiate viral entry. The binding of HN or G to its receptor on a target cell triggers the activation of F, which then inserts into the target cell and mediates the membrane fusion that initiates infection. We have shown that for paramyxoviruses, the inhibitory efficacy of HR peptides is inversely proportional to the rate of F activation. For HIV-1, the antiviral potency of an HRC-derived peptide can be dramatically increased by targeting it to the membrane microdomains where fusion occurs, via the addition of a cholesterol group. We report here that for three paramyxoviruses—human parainfluenza virus type 3 (HPIV3), a major cause of lower respiratory tract diseases in infants, and the emerging zoonotic viruses Hendra virus (HeV) and Nipah virus (NiV), which cause lethal central nervous system diseases—the addition of cholesterol to a paramyxovirus HRC-derived peptide increased antiviral potency by 2 log units. Our data suggest that this enhanced activity is indeed the result of the targeting of the peptide to the plasma membrane, where fusion occurs. The cholesterol-tagged peptides on the cell surface create a protective antiviral shield, target the F protein directly at its site of action, and expand the potential utility of inhibitory peptides for paramyxoviruses.Fusion of enveloped viruses with the host cell is a key step in viral infectivity, and interference with this process can lead to highly effective antivirals. Viral fusion is driven by specialized proteins that undergo an ordered series of conformational changes. These changes facilitate the initial, close apposition of the viral and host membranes, and they ultimately result in the formation of a fusion pore (reviewed in reference 12). The “class I” fusion proteins harbor two regions, typically two heptad repeat (HR) domains: the first one (HRN) adjacent to the fusion peptide and the second one (HRC) immediately preceding the transmembrane domain. Peptides derived from the HR regions can inhibit fusion, and one of them, T20 (enfuvirtide), is in clinical use for HIV-1 (19). Peptides derived from the HRN and HRC regions of paramyxovirus fusion (F) proteins can interact with fusion intermediates of F (3, 20, 22, 37, 46, 49) and provide a promising antiviral strategy.The current model for class I-driven fusion postulates the existence of a so-called prehairpin intermediate, a high-energy structure that bridges the viral and cell membranes, where the HRN and the HRC are separated. The prehairpin intermediate spontaneously collapses into the postfusion structure—a six-helical bundle (6HB), with an inner trimeric coiled-coil formed by the HRN onto which the HRC folds (12, 14, 30, 40). The key to these events is the initial activation step, whereby HN triggers F to initiate the process. Structural and biophysical analyses of the paramyxovirus 6HB (30, 50, 51) suggest that inhibitors bind to the prehairpin intermediate and prevent its transition to the 6HB, thus inhibiting viral entry. The peptides bind to their complementary HR region and thereby prevent HRN and HRC from refolding into the stable 6HB structure required for fusion (3, 10, 40). The efficiency of F triggering by HN critically influences the degree of fusion mediated by F and thus the extent of viral entry (35). In addition, differences in the efficiency of triggering of the fusion process impact the efficacy of potential antiviral molecules that target intermediate states of the fusion protein (36).Paramyxoviruses cause important human illnesses, significantly contributing to global disease and mortality, ranging from lower-respiratory-tract diseases in infants caused by human parainfluenza virus types 1, 2, and 3 (HPIV1, -2, and -3) (9, 48), to highly lethal central nervous system diseases caused by the emerging paramyxoviruses HeV and NiV. No antiviral therapies or vaccines yet exist for these paramyxoviruses, and vaccines would be unlikely to protect the youngest infants. Antiviral agents, therefore, would be particularly beneficial. All paramyxoviruses possess two envelope glycoproteins directly involved in viral entry and pathogenesis: a fusion protein (F) and a receptor-binding protein (HN, H, or G). The paramyxovirus F proteins belong to the group of “class I” fusion proteins (44, 45), which also include the influenza virus hemagglutinin protein and the HIV-1 fusion protein gp120. The F protein is synthesized as a precursor protein (F0) that is proteolytically processed posttranslationally to form a trimer of disulfide-linked heterodimers (F1-F2). This cleavage event places the fusion peptide at the F1 terminus in the mature F protein and is essential for membrane fusion activity. The exact triggers that initiate a series of conformational changes in F leading to membrane fusion differ depending on the pathway the virus uses to enter the cell. In the case of HPIV, HeV, and NiV, the receptor-binding protein, hemagglutinin-neuraminidase (HN) (in HPIV3) or G (in HeV and NiV), binds to cellular surface receptors, brings the viral envelope into proximity with the plasma membrane, and activates the viral F protein. This receptor-ligand interaction is required for the F protein to mediate the fusion of the viral envelope with the host cell membrane (23, 33, 35).The HRC peptide regions of a number of paramyxoviruses, including Sendai virus, measles virus, Newcastle disease virus (NDV), respiratory syncytial virus (RSV), simian virus 5 (SV5), Hendra virus (HeV), and Nipah virus (NiV), can inhibit the infectivity of the homologous virus (17, 20, 31, 37, 47, 49, 52, 53). Recently, we showed that peptides derived from the HRC region of the F protein of HPIV3 are effective inhibitors of both HPIV and HeV/NiV fusion (31) and that, for HeV, the strength of HRC peptide binding to the corresponding HRN region correlates with the potency of fusion and infection inhibition (30). However, peptides derived from the HPIV3 F protein HRC region are more effective at inhibiting HeV/NiV fusion than HPIV3 fusion, despite a stronger homotypic HRN-HRC interaction for HPIV3 (30, 31). We showed (36) that the kinetics of fusion (kinetics of F activation) impacts sensitivity to inhibition by peptides, as is the case for HIV (39). Alterations in HPIV3 HN′s property of F activation affect the kinetics of F''s progression through its conformational changes, thus altering inhibitor efficacy. Once the extended intermediate stage of F has passed, and fusion proceeds, peptide inhibitors are ineffective. We have proposed that the design of effective inhibitors may require either targeting an earlier stage of F activation or increasing the concentration of inhibitor at the location of receptor binding, in order to enhance the access and association of the inhibitor with the intermediate-stage fusion protein (36).A substantial body of evidence supports the notion that viral fusion occurs in confined areas of the interacting viral and host membranes (26). For HIV-1, the lipid composition of the viral membrane is strikingly different from that of the host cell membrane; the former is particularly enriched in cholesterol and sphingomyelin (4, 5, 7, 8). Cholesterol and sphingolipids are often laterally segregated in membrane microdomains or “lipid rafts” (7, 11). In fact, the antiviral potency of the HIV-inhibitory HRC peptide C34 is dramatically increased by targeting it to the “lipid rafts” via the addition of a cholesterol group (16).We applied the targeting strategy based on cholesterol derivatization to paramyxoviruses, and we show here that by adding a cholesterol tag to HPIV3-derived HRC E459V (30) inhibitory peptides, we increased antiviral potency by 2 log units (50% inhibitory concentrations [IC₅₀], <2 nM). We chose to use the HPIV3-derived peptides for HeV/NiV, because we have previously shown that they are far more effective inhibitors of HeV and NiV than the homotypic peptides (30, 31). We propose that the enhanced activity resulting from the addition of a cholesterol tag is a result of the targeting of the peptide to the plasma membrane, where fusion occurs.     

Method for tracking nanogel particles in vivo and in vitro

Hydrogels made of N-isopropylacrylamide (NIPA) can be synthesized in the form of highly monodispersed nanoparticles. After synthesis, NIPA hydrogel nanoparticles (nanogels) can be labeled by Alexa Fluor 488 carboxylic acid, 2,3,5,6-tetrafluorophenyl ester through amine-terminated functional groups. This choice of dye is complementary to other biological labeling methods for in vivo studies. When the nanogel/dye nanoparticles are injected into rabbits, they can be imaged via tissue sectioning and confocal microscopy, while nanoparticle concentration can be determined by fluorescent microplate assays. Time-course persistence of nanoparticles in the circulatory system can be readily tracked by direct assay of plasma and urine samples using 485 nm excitation and 538 emission wavelengths to keep background fluorescence to nearly the same level as that found using an empty well. Depending upon how the nanoparticles are injected, circulatory system concentrations can reach high concentrations and diminish to low levels or gradually increase and gradually decrease over time. Injection in the femoral artery results in a rapid spike in circulating nanogel/dye concentration, while injection into the renal artery results in a more gradual increase.     

Modeling of growth and laccase production by Pycnoporus sanguineus

Production of extracellular laccase by the white-rot fungus Pycnoporus sanguineus was examined in batch submerged cultures in shake flasks, baffled shake flasks and a stirred tank bioreactor. The biomass growth in the various culture systems closely followed a logistic growth model. The production of laccase followed a Luedeking-Piret model. A modified Luedeking-Piret model incorporating logistic growth effectively described the consumption of glucose. Biomass productivity, enzyme productivity and substrate consumption were enhanced in baffled shake flasks relative to the cases for the conventional shake flasks. This was associated with improved oxygen transfer in the presence of the baffles. The best results were obtained in the stirred tank bioreactor. At 28 °C, pH 4.5, an agitation speed of 600 rpm and a dissolved oxygen concentration of ~25 % of air saturation, the laccase productivity in the bioreactor exceeded 19 U L^?1 days^?1, or 1.5-fold better than the best case for the baffled shake flask. The final concentration of the enzyme was about 325 U L^?1.