Lysoglycerophospholipids in chronic inflammatory disorders: The PLA2/LPC and ATX/LPA axes

Lysophosphatidylcholine (LPC) and lysophosphatidic acid (LPA), the most prominent lysoglycerophospholipids, are emerging as a novel class of inflammatory lipids, joining thromboxanes, leukotrienes and prostaglandins with which they share metabolic pathways and regulatory mechanisms. Enzymes that participate in LPC and LPA metabolism, such as the phospholipase A₂ superfamily (PLA₂) and autotaxin (ATX, ENPP2), play central roles in regulating LPC and LPA levels and consequently their actions. LPC/LPA biosynthetic pathways will be briefly presented and LPC/LPA signaling properties and their possible functions in the regulation of the immune system and chronic inflammation will be reviewed. Furthermore, implications of exacerbated LPC and/or LPA signaling in the context of chronic inflammatory diseases, namely rheumatoid arthritis, multiple sclerosis, pulmonary fibrosis and hepatitis, will be discussed. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.     

A basic peptide derived from the HARP C-terminus inhibits anchorage-independent growth of DU145 prostate cancer cells

Heparin affin regulatory peptide (HARP) is an 18 kDa heparin-binding protein that plays a key role in tumor growth. We showed previously that the synthetic peptide P(111-136) composed of the last 26 HARP amino acids inhibited HARP-induced mitogenesis. Here, to identify the exact molecular domain involved in HARP inhibition, we investigated the effect of the shorter basic peptide P(122-131) on DU145 cells, which express HARP and its receptor protein tyrosine phosphatase beta/zeta (RPTPbeta/zeta). P(122-131) was not cytotoxic; it dose-dependently inhibited anchorage-independent growth of DU145 cells. Binding studies using biotinylated P(122-131) indicated that this peptide interfered with HARP binding to DU145 cells. Investigation of the mechanisms involved suggested interference, under anchorage-independent conditions, of P(122-131) with a HARP autocrine loop in an RPTPbeta/zeta-dependent fashion. Thus, P(122-131) may hold potential for the treatment of disorders involving RPTPbeta/zeta.     

Loss of Receptor Protein Tyrosine Phosphatase β/ζ (RPTPβ/ζ) Promotes Prostate Cancer Metastasis

Pleiotrophin is a growth factor that induces carcinogenesis. Despite the fact that many published reports focused on the role of pleiotrophin and its receptors, receptor protein tyrosine phosphatase (RPTPβ/ζ), and syndecan-3 during tumor development, no information is available regarding their function in tumor metastasis. To investigate the mechanism through which pleiotrophin regulates tumor metastasis, we used two different prostate carcinoma cell lines, DU145 and PC3, in which the expression of RPTPβ/ζ or syndecan-3 was down-regulated by the RNAi technology. The loss of RPTPβ/ζ expression initiated epithelial-to-mesenchymal transition (EMT) and increased the ability of the cells to migrate and invade. Importantly, the loss of RPTPβ/ζ expression increased metastasis in nude mice in an experimental metastasis assay. We also demonstrate that RPTPβ/ζ counterbalanced the pleiotrophin-mediated syndecan-3 pathway. While the inhibition of syndecan-3 expression inhibited the pleiotrophin-mediated cell migration and attachment through the Src and Fak pathway, the inhibition of RPTPβ/ζ expression increased pleiotrophin-mediated migration and attachment through an interaction with Src and the subsequent activation of a signal transduction pathway involving Fak, Pten, and Erk1/2. Taken together, these results suggest that the loss of RPTPβ/ζ may contribute to the metastasis of prostate cancer cells by inducing EMT and promoting pleiotrophin activity through the syndecan-3 pathway.     

Mycelium growth kinetics and optimal temperature conditions for the cultivation of edible mushroom species on lignocellulosic substrates

The influence of environmental parameters on mycelial linear growth ofPleurotus ostreatus, P. eryngii, P. pulmonarius, Agrocybe aegerita, Lentinula edodes, Volvariella volvacea andAuricularia auricula-judae was determined in two different nutrient media in a wide range of temperature, forming the basis for the assessment of their temperature optimaV. volvacea grew faster at 35°C,P. eryngii at 25°C,P. ostreatus andP. pulmonarius at 30°C,A. aegerita at 25 or 30°C andA. auricula-judae at 20 or 25°C depending on the nutrient medium used andL. edodes at 20 or 30°C depending on the strain examined. The mycelium extension rates were evaluated on seven mushroom cultivation substrates: wheat straw, cotton gin-trash, peanut shells, poplar sawdust, oak sawdust, corn cobs and olive press-cake. The mycelium extension rates (linear growth and colonization rates) were determined by the ‘race-tube’ technique, and were found to be the highest on cotton gin-trash, peanut shells and poplar sawdust forPleurotus spp. andA. aegerita. Wheat straw, peanut shells and particularly cotton gin-trash supported fast growth ofV. volvacea, whereas wheat straw was the most suitable substrate forL. edodes andA. auricula-judae. Supplemented oak sawdust and olive press-cake were poor substrates for most species examined, white almost all strains performed adequately on corn cobs.     

Proteome profile of functional mitochondria from human skeletal muscle using one-dimensional gel electrophoresis and HPLC-ESI-MS/MS

Mitochondria can be isolated from skeletal muscle in a manner that preserves tightly coupled bioenergetic function in vitro. The purpose of this study was to characterize the composition of such preparations using a proteomics approach. Mitochondria isolated from human vastus lateralis biopsies were functional as evidenced by their response to carbohydrate and fat-derived fuels. Using one-dimensional gel electrophoresis and HPLC-ESI-MS/MS, 823 unique proteins were detected, and 487 of these were assigned to the mitochondrion, including the newly characterized SIRT5, MitoNEET and RDH13. Proteins detected included 9 of the 13 mitochondrial DNA-encoded proteins and 86 of 104 electron transport chain (ETC) and ETC-related proteins. In addition, 59 of 78 proteins of the 55S mitoribosome, several TIM and TOM proteins and cell death proteins were present. This study presents an efficient method for future qualitative assessments of proteins from functional isolated mitochondria from small samples of healthy and diseased skeletal muscle.     

Biotechnological conversion of waste cooking olive oil into lipid-rich biomass using Aspergillus and Penicillium strains

Aims: In this study, we have investigated the biochemical behaviour of Aspergillus sp. (five strains) and Penicillium expansum (one strain) fungi cultivated on waste cooking olive oil. The production of lipid‐rich biomass was the main target of the work. In parallel, the biosynthesis of other extracellular metabolites (organic acids) and enzyme (lipase) and the substrate fatty acid specificity of the strains were studied. Methods and Results: Carbon‐limited cultures were performed on waste oil, added in the growth medium at 15 g l^?1, and high biomass quantities were produced (up to c. 18 g l^?1, conversion yield of c. 1·0 g of dry biomass formed per g of fat consumed or higher). Cellular lipids were accumulated in notable quantities in almost all cultures. Aspergillus sp. ATHUM 3482 accumulated lipid up to 64·0% (w/w) in dry fungal mass. In parallel, extracellular lipase activity was quantified, and it was revealed to be strain and fermentation time dependent, with a maximum quantity of 645 U ml^?1 being obtained by Aspergillus niger NRRL 363. Storage lipid content significantly decreased at the stationary growth phase. Some differences in the fatty acid composition of both cellular and residual lipids when compared with the initial substrate fat used were observed; in various cases, cellular lipids more saturated and enriched with arachidic acid were produced. Aspergillus strains produced oxalic acid up to 5·0 g l^?1. Conclusions: Aspergillus and Penicillium strains are able to convert waste cooking olive oil into high‐added‐value products. Significance and Impact of the Study: Increasing fatty wastes amounts are annually produced. The current study provided an alternative way of biovalourization of these materials, by using them as substrates, to produce added‐value compounds.     

The cabbage aphid: a walking mustard oil bomb

The cabbage aphid, Brevicoryne brassicae, has developed a chemical defence system that exploits and mimics that of its host plants, involving sequestration of the major plant secondary metabolites (glucosinolates). Like its host plants, the aphid produces a myrosinase (beta-thioglucoside glucohydrolase) to catalyse the hydrolysis of glucosinolates, yielding biologically active products. Here, we demonstrate that aphid myrosinase expression in head/thoracic muscle starts during embryonic development and protein levels continue to accumulate after the nymphs are born. However, aphids are entirely dependent on the host plant for the glucosinolate substrate, which they store in the haemolymph. Uptake of a glucosinolate (sinigrin) was investigated when aphids fed on plants or an in vitro system and followed a different developmental pattern in winged and wingless aphid morphs. In nymphs of the wingless aphid morph, glucosinolate level continued to increase throughout the development to the adult stage, but the quantity in nymphs of the winged form peaked before eclosion (at day 7) and subsequently declined. Winged aphids excreted significantly higher amounts of glucosinolate in the honeydew when compared with wingless aphids, suggesting regulated transport across the gut. The higher level of sinigrin in wingless aphids had a significant negative impact on survival of a ladybird predator. Larvae of Adalia bipunctata were unable to survive when fed adult wingless aphids from a 1% sinigrin diet, but survived successfully when fed aphids from a glucosinolate-free diet (wingless or winged), or winged aphids from 1% sinigrin. The apparent lack of an effective chemical defence system in adult winged aphids possibly reflects their energetic investment in flight as an alternative predator avoidance mechanism.     

Translation elongation can control translation initiation on eukaryotic mRNAs

Synonymous codons encode the same amino acid, but differ in other biophysical properties. The evolutionary selection of codons whose properties are optimal for a cell generates the phenomenon of codon bias. Although recent studies have shown strong effects of codon usage changes on protein expression levels and cellular physiology, no translational control mechanism is known that links codon usage to protein expression levels. Here, we demonstrate a novel translational control mechanism that responds to the speed of ribosome movement immediately after the start codon. High initiation rates are only possible if start codons are liberated sufficiently fast, thus accounting for the observation that fast codons are overrepresented in highly expressed proteins. In contrast, slow codons lead to slow liberation of the start codon by initiating ribosomes, thereby interfering with efficient translation initiation. Codon usage thus evolved as a means to optimise translation on individual mRNAs, as well as global optimisation of ribosome availability.