Monomeric Re lipopolysaccharide from Escherichia coli is more active than the aggregated form in the Limulus amebocyte lysate assay and in inducing Egr-1 mRNA in murine peritoneal macrophages.

Takayama, K.; Mitchell, D. H.; Din, Zafeer Z.; Mukerjee, Pasupati; Li, Ching; Coleman, David L.

doi:10.1016/s0021-9258(17)42159-4

Cited by 114 publications

(21 citation statements)

References 13 publications

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“…The complete amino acid sequence of this enzyme has been described previously [23,24]. The absence of endotoxin contamination in the MT-III batches used was demonstrated by a quantitative LAL test [25], which revealed undetectable levels of endotoxin (0.125 EU/mL).…”

Section: Phospholipase a 2 (Pla 2 )mentioning

confidence: 99%

A Representative GIIA Phospholipase A2 Activates Preadipocytes to Produce Inflammatory Mediators Implicated in Obesity Development

et al. 2020

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Adipose tissue secretes proinflammatory mediators which promote systemic and adipose tissue inflammation seen in obesity. Group IIA (GIIA)-secreted phospholipase A2 (sPLA2) enzymes are found to be elevated in plasma and adipose tissue from obese patients and are active during inflammation, generating proinflammatory mediators, including prostaglandin E2 (PGE2). PGE2 exerts anti-lipolytic actions and increases triacylglycerol levels in adipose tissue. However, the inflammatory actions of GIIA sPLA2s in adipose tissue cells and mechanisms leading to increased PGE2 levels in these cells are unclear. This study investigates the ability of a representative GIIA sPLA2, MT-III, to activate proinflammatory responses in preadipocytes, focusing on the biosynthesis of prostaglandins, adipocytokines and mechanisms involved in these effects. Our results showed that MT-III induced biosynthesis of PGE2, PGI2, MCP-1, IL-6 and gene expression of leptin and adiponectin in preadipocytes. The MT-III-induced PGE2 biosynthesis was dependent on cytosolic PLA2 (cPLA2)-α, cyclooxygenases (COX)-1 and COX-2 pathways and regulated by a positive loop via the EP4 receptor. Moreover, MT-III upregulated COX-2 and microsomal prostaglandin synthase (mPGES)-1 protein expression. MCP-1 biosynthesis induced by MT-III was dependent on the EP4 receptor, while IL-6 biosynthesis was dependent on EP3 receptor engagement by PGE2. These data highlight preadipocytes as targets for GIIA sPLA2s and provide insight into the roles played by this group of sPLA2s in obesity.

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Section: Phospholipase a 2 (Pla 2 )mentioning

confidence: 99%

A Representative GIIA Phospholipase A2 Activates Preadipocytes to Produce Inflammatory Mediators Implicated in Obesity Development

et al. 2020

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“…The complete amino acid sequence and toxicological profile of these enzymes have been previously described in detail [37]. The absence of endotoxin contamination in the batches used was demonstrated by performing the quantitative Limulus amebocyte lysate assay [39], which revealed no detectable levels of endotoxin (< 0.125 EU/mL).…”

Section: Enzymesmentioning

confidence: 99%

A Lipidomic Perspective of the Action of Group IIA Secreted Phospholipase A2 on Human Monocytes: Lipid Droplet Biogenesis and Activation of Cytosolic Phospholipase A2α

et al. 2020

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Phospholipase A2s constitute a wide group of lipid-modifying enzymes which display a variety of functions in innate immune responses. In this work, we utilized mass spectrometry-based lipidomic approaches to investigate the action of Asp-49 Ca2+-dependent secreted phospholipase A2 (sPLA2) (MT-III) and Lys-49 sPLA2 (MT-II), two group IIA phospholipase A2s isolated from the venom of the snake Bothrops asper, on human peripheral blood monocytes. MT-III is catalytically active, whereas MT-II lacks enzyme activity. A large decrease in the fatty acid content of membrane phospholipids was detected in MT III-treated monocytes. The significant diminution of the cellular content of phospholipid-bound arachidonic acid seemed to be mediated, in part, by the activation of the endogenous group IVA cytosolic phospholipase A2α. MT-III triggered the formation of triacylglycerol and cholesterol enriched in palmitic, stearic, and oleic acids, but not arachidonic acid, along with an increase in lipid droplet synthesis. Additionally, it was shown that the increased availability of arachidonic acid arising from phospholipid hydrolysis promoted abundant eicosanoid synthesis. The inactive form, MT-II, failed to produce any of the effects described above. These studies provide a complete lipidomic characterization of the monocyte response to snake venom group IIA phospholipase A2, and reveal significant connections among lipid droplet biogenesis, cell signaling and biochemical pathways that contribute to initiating the inflammatory response.

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“…The supramolecular structures of various LPSs have been extensively studied by x-ray diffraction (Burge and Draper, 1967;Kastowsky et al, 1993;Seydel et al, 1993a,b;Kato et al, 1993;Snyder et al, 1999) because of their roles both as a toxin and as a component of the bacterial outer membrane barrier. That is, the interactions between LPS and cells, antibiotics, and antimicrobial peptides are all thought to depend on LPS aggregation and packing properties (Galanos and Luderitz, 1984;Labischinski et al, 1985;Seydel and Brandenburg, 1990;Brandenburg, 1993;Rietschel et al, 1994;Takayama et al, 1994). Compared to typical phospholipid bilayers, LPS membranes have tighter hydrocarbon chain packing that may play a critical role in its barrier properties (Snyder et al, 1999;Snyder and McIntosh, 2000;Allende and McIntosh, 2003).…”

Section: Introductionmentioning

confidence: 99%

Structure of Supported Bilayers Composed of Lipopolysaccharides and Bacterial Phospholipids: Raft Formation and Implications for Bacterial Resistance

Tong

McIntosh

2004

Biophysical Journal

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Lipopolysaccharide (LPS), the major lipid on the surface of Gram-negative bacteria, plays a key role in bacterial resistance to hydrophobic antibiotics and antimicrobial peptides. Using atomic force microscopy (AFM) we characterized supported bilayers composed of LPSs from two bacterial chemotypes with different sensitivities to such antibiotics and peptides. Rd LPS, from more sensitive "deep rough" mutants, contains only an inner saccharide core, whereas Ra LPS, from "rough" mutants, contains a longer polysaccharide region. A vesicle fusion technique was used to deposit LPS onto either freshly cleaved mica or polyethylenimine-coated mica substrates. The thickness of the supported bilayers measured with contact-mode AFM was 7 nm for Rd LPS and 9 nm for Ra LPS, consistent with previous x-ray diffraction measurements. In water the Ra LPS bilayer surface was more disordered than Rd LPS bilayers, likely due to the greater volume occupied by the longer Ra LPS polysaccharide region. Since deep rough mutants contain bacterial phospholipid (BPL) as well as LPS on their surfaces, we also investigated the organization of Rd LPS/BPL bilayers. Differential scanning calorimetry and x-ray diffraction indicated that incorporation of BPL reduced the phase transition temperature, enthalpy, and average bilayer thickness of Rd LPS. For Rd LPS/BPL mixtures, AFM showed irregularly shaped regions thinner than Rd LPS bilayers by 2 nm (the difference in thickness between Rd LPS and BPL bilayers), whose area increased with increasing BPL concentration. We argue that the increased permeability of deep rough mutants is due to structural modifications caused by BPL to the LPS membrane, in LPS hydrocarbon chain packing and in the formation of BPL-enriched microdomains.

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Monomeric Re lipopolysaccharide from Escherichia coli is more active than the aggregated form in the Limulus amebocyte lysate assay and in inducing Egr-1 mRNA in murine peritoneal macrophages.

Cited by 114 publications

References 13 publications

A Representative GIIA Phospholipase A2 Activates Preadipocytes to Produce Inflammatory Mediators Implicated in Obesity Development

A Representative GIIA Phospholipase A2 Activates Preadipocytes to Produce Inflammatory Mediators Implicated in Obesity Development

A Lipidomic Perspective of the Action of Group IIA Secreted Phospholipase A2 on Human Monocytes: Lipid Droplet Biogenesis and Activation of Cytosolic Phospholipase A2α

Structure of Supported Bilayers Composed of Lipopolysaccharides and Bacterial Phospholipids: Raft Formation and Implications for Bacterial Resistance

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