Total direct chemical synthesis and biological activities of human group IIA secretory phospholipase A2.
Ontology highlight
ABSTRACT:
SUBMITTER: Dong CZ
PROVIDER: S-EPMC1222685 | biostudies-other | 2002 Jul
REPOSITORIES: biostudies-other
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Project description:Simplified analogs of YM-26734, a known inhibitor of secreted phospholipase A(2) (sPLA(2)) group IIA, were synthesized and found to also display potent inhibition at low nanomolar concentrations. Analogs were based on the didodecanoylphloroglucinol portion of YM-26734 which contains the predicted active site calcium binding group.
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Project description:Although benign hepatocellular adenomas (HCA) are very rare, recent observations have shown their occurrence in patients with diabetes mellitus. Consequently, most of these cases are treated by resection due to concerns regarding their potential progression to hepatocarcinoma (HCC). This decision is largely driven by the limited number of studies on HCC subtyping and the lack of molecular and biological insights into the carcinogenic potential of benign tumors. This study aimed to comprehensively investigate the subtype classification of HCA and to compare and analyze gene expression profiling between HCA and HCC tissues. One fresh inflammatory HCA (I-HCA), three non-B non-C HCCs, two hepatitis B virus-HCCs, and one normal liver tissue sample were subjected to single-cell RNA sequencing (scRNA-seq). Comparative analysis of scRNA-seq among different tissues showed that phospholipase A2 group IIA (PLA2G2A) mRNA was specifically expressed in I-HCA, following RNA-seq analysis in formalin-fixed paraffin-embedded tissues from other HCAs. Immunohistochemistry using the PLA2G2A antibody in these tissues indicated that the positive reaction was mainly observed in hepatocytes of I-HCAs and stromal cells surrounding the tumor tissue in HCC were also stained. According to a clinical database, PLA2G2A expression in HCC does not correlate with poor prognosis. This finding may potentially help develop a new definition for I-HCA, resulting in a significant clinical contribution, but it requires validation with other fresh HCA samples.
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Project description:The acute phase protein group IIA secretory phospholipase A2 (sPLA2-IIA) has intrinsic proatherosclerotic properties. The present prospective cohort study investigated whether plasma sPLA2-IIA associates with graft failure, cardiovascular, and all-cause mortality in renal transplant recipients (RTRs), patients with accelerated atherosclerosis formation both systemically and within the graft. In 511 RTRs from a single academic center with stable graft function >1 year, baseline plasma sPLA2-IIA was determined by ELISA. Primary end points were death-censored graft failure and mortality (median follow-up, 7.0 years). Baseline sPLA2-IIA was higher in RTRs than in healthy controls (median 384 ng/dL (range 86-6951) vs. 185 ng/dL (range 104-271), p < 0.001). Kaplan-Meier analysis demonstrated increased risk for graft failure (p = 0.002), as well as cardiovascular (p < 0.001) and all-cause mortality (p < 0.001), with increasing sPLA2-IIA quartiles. Cox regression showed strong associations of sPLA2-IIA with increased risks of graft failure (hazard ratio (HR) = 1.42 (1.11-1.83), p = 0.006), as well as cardiovascular (HR = 1.48 (1.18-1.85), p = 0.001) and all-cause mortality (HR = 1.39 (1.17-1.64), p < 0.001), dependent on parameters of kidney function. Renal function during follow-up declined faster in RTRs with higher baseline sPLA2-IIA levels. In RTRs, sPLA2-IIA is a significant predictive biomarker for chronic graft failure, as well as overall and cardiovascular disease mortality dependent on kidney function. This dependency is conceivably explained by sPLA2-IIA impacting negatively on kidney function.
| S-EPMC7288094 | biostudies-literature
Project description:BackgroundSecretory phospholipase A2 group IIA (sPLA2-IIA) has been identified as a biomarker of atherosclerosis in observational and animal studies. The protein is encoded by the PLA2G2A gene and the aim of this study was to test the functionality of two PLA2G2A non-coding SNPs, rs11573156 C>G and rs3767221 T>G where the rare alleles have been previously associated with higher and lower sPLA2-IIA levels respectively.Methodology/principal findingsLuciferase assays, electrophoretic mobility shift assays (EMSA), and RNA expression by RT-PCR were used to examine allelic differences. For rs3767221 the G allele showed ∼55% lower luciferase activity compared to the T allele (T = 62.1 (95% CI 59.1 to 65.1) G = 27.8 (95% CI 25.0 to 30.6), p = 1.22×10⁻³⁵, and stronger EMSA binding of a nuclear protein compared to the T-allele. For rs11573156 C >G there were no luciferase or EMSA allelic differences seen. In lymphocyte cell RNA, from individuals of known rs11573156 genotype, there was no allelic RNA expression difference for exons 5 and 6, but G allele carriers (n = 7) showed a trend to lower exon 1-2 expression compared to CC individuals. To take this further, in the ASAP study (n = 223), an rs11573156 proxy (r² = 0.91) showed ∼25% higher liver expression of PLA2G2A (1.67×10⁻¹⁷) associated with the G allele. However, considering exon specific expression, the association was greatly reduced for exon 2 (4.5×10⁻⁵) compared to exons 3-6 (10⁻¹⁰ to 10⁻²⁰), suggesting rs11573156 G allele-specific exon 2 skipping.ConclusionBoth SNPs are functional and provide useful tools for Mendelian Randomisation to determine whether the relationship between sPLA2-IIA and coronary heart disease is causal.
| S-EPMC3412631 | biostudies-literature
Project description:Secretory phospholipase A(2)s (sPLA(2)) hydrolyze glycerophospholipids to liberate lysophospholipids and free fatty acids. Although group X (GX) sPLA(2) is recognized as the most potent mammalian sPLA(2) in vitro, its precise physiological function(s) remains unclear. We recently reported that GX sPLA(2) suppresses activation of the liver X receptor in macrophages, resulting in reduced expression of liver X receptor-responsive genes including ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1), and a consequent decrease in cellular cholesterol efflux and increase in cellular cholesterol content (Shridas et al. 2010. Arterioscler. Thromb. Vasc. Biol. 30: 2014-2021). In this study, we provide evidence that GX sPLA(2) modulates macrophage inflammatory responses by altering cellular cholesterol homeostasis. Transgenic expression or exogenous addition of GX sPLA(2) resulted in a significantly higher induction of TNF-?, IL-6, and cyclooxygenase-2 in J774 macrophage-like cells in response to LPS. This effect required GX sPLA(2) catalytic activity, and was abolished in macrophages that lack either TLR4 or MyD88. The hypersensitivity to LPS in cells overexpressing GX sPLA(2) was reversed when cellular free cholesterol was normalized using cyclodextrin. Consistent with results from gain-of-function studies, peritoneal macrophages from GX sPLA(2)-deficient mice exhibited a significantly dampened response to LPS. Plasma concentrations of inflammatory cytokines were significantly lower in GX sPLA(2)-deficient mice compared with wild-type mice after LPS administration. Thus, GX sPLA(2) amplifies signaling through TLR4 by a mechanism that is dependent on its catalytic activity. Our data indicate this effect is mediated through alterations in plasma membrane free cholesterol and lipid raft content.
| S-EPMC3119755 | biostudies-literature
Project description:Studies in vitro indicate that group X secretory phospholipase A(2) (GX sPLA(2)) potently releases arachidonic acid (AA) and lysophosphatidylcholine from mammalian cell membranes. To define the function of GX sPLA(2) in vivo, our laboratory recently generated C57BL/6 mice with targeted deletion of GX sPLA(2) (GX(-/-) mice). When fed a normal rodent diet, GX(-/-) mice gained significantly more weight and had increased adiposity compared to GX(+/+) mice, which was not attributable to alterations in food consumption or energy expenditure. When treated with adipogenic stimuli ex vivo, stromal vascular cells isolated from adipose tissue of GX(-/-) mice accumulated significantly more (20%) triglyceride compared to cells from GX(+/+) mice. Conversely, overexpression of GX sPLA(2), but not catalytically inactive GX sPLA(2), resulted in a significant 50% reduction in triglyceride accumulation in OP9 adipocytes. The induction of genes encoding adipogenic proteins (PPAR?, SREBP-1c, SCD1, and FAS) was also significantly blunted by 50-80% in OP9 cells overexpressing GX sPLA(2). Activation of the liver X receptor (LXR), a nuclear receptor known to up-regulate adipogenic gene expression, was suppressed in 3T3-L1 and OP9 cells when GX sPLA(2) was overexpressed. Thus, hydrolytic products generated by GX sPLA(2) negatively regulate adipogenesis, possibly by suppressing LXR activation.
| S-EPMC2974424 | biostudies-literature
Project description:IntroductionThis paper investigates the role of Group II Secretory Phospholipase A2 (sPLA2-IIA) as a biomarker for the diagnosis of sepsis and bacterial infection in adults. Sepsis and bacterial infection are common problems encountered by patients in the hospital and often carry adverse outcomes if not managed early.MethodsTwo independent reviewers conducted a comprehensive search using Ovid MEDLINE published from years 1993 to 2016 and SCOPUS published from year 1985 to 2017 to screen for relevant studies. The main inclusion criteria included adult subjects, patients with suspected or confirmed signs of infection and relevant outcomes which looked into the role of sPLA2-IIA in detecting the presence of sepsis and bacterial infection in the subjects.Results and discussionFour studies met the inclusion criteria. SPLA2-IIA was found to be effective in detecting the presence of sepsis and bacterial infection in adults. The levels of serum sPLA2-IIA also correlated well with the presence of sepsis and bacterial infection.ConclusionThis systematic review highlights the role of sPLA2-IIA as a reliable tool to diagnose sepsis and bacterial infection in adult patients. Nonetheless, further studies should be done in the future to provide more compelling evidence on its application in the clinical setting.
| S-EPMC5495423 | biostudies-literature
Project description:Besides promoting inflammation by mobilizing lipid mediators, secreted phospholipase A2 group IIA (sPLA2-IIA) prevents bacterial infection by degrading bacterial membranes. Here we show that despite the restricted intestinal expression of sPLA2-IIA in BALB/c mice, its genetic deletion leads to amelioration of cancer and exacerbation of psoriasis in distal skin. Intestinal expression of sPLA2-IIA is reduced after antibiotics treatment or under germ-free conditions, suggesting its upregulation by gut microbiota. Metagenome, transcriptome and metabolome analyses have revealed that sPLA2-IIA deficiency alters the gut microbiota, accompanied by notable changes in the intestinal expression of genes related to immunity and metabolism as well as the levels of various blood metabolites and fecal bacterial lipids, suggesting that sPLA2-IIA contributes to shaping of the gut microbiota. The skin phenotypes in Pla2g2a–/– mice are lost when they are co-housed with littermate wild-type mice, resulting in mixing of the microbiota between the genotypes, or when they are housed in a more stringent pathogen-free facility, where Pla2g2a expression in wild-type mice is low and the gut microbial compositions in both genotypes are nearly identical. Thus, our results highlight a new aspect of sPLA2-IIA as a modulator of gut microbiota, perturbation of which affects distal skin responses.
2022-01-01 | GSE182283 | GEO
Project description:Human group IIA secretory phospholipase A2 (hGIIA) promotes the proliferation of cancer cells, making it a compelling therapeutic target, but it is also significant in other inflammatory conditions. Consequently, suitable inhibitors of hGIIA have always been sought. The activation of phospholipases A2 and the catalysis of glycerophospholipid substrates generally leads to the release of fatty acids such as arachidonic acid (AA) and lysophospholipid, which are then converted to mediator compounds, including prostaglandins, leukotrienes, and the platelet-activating factor. However, this ability of hGIIA to provide AA is not a complete explanation of its biological role in inflammation, as it has now been shown that it also exerts proinflammatory effects by a catalysis-independent mechanism. This mechanism is likely to be highly dependent on key specific molecular interactions, and the full mechanistic descriptions of this remain elusive. The current candidates for the protein partners that may mediate this catalysis-independent mechanism are also introduced in this review. A key discovery has been that selective inhibition of the catalysis-independent activity of hGIIA is achieved with cyclised derivatives of a pentapeptide, FLSYK, derived from the primary sequence of hGIIA. The effects of hGIIA on cell function appear to vary depending on the pathology studied, and so its mechanism of action is complex and context-dependent. This review is comprehensive and covers the most recent developments in the understanding of the many facets of hGIIA function and inhibition and the insight they provide into their clinical application for disease treatment. A cyclic analogue of FLSYK, c2, the most potent analogue known, has now been taken into clinical trials targeting advanced prostate cancer.
| S-EPMC7583969 | biostudies-literature
Project description:Group IIA secretory phospholipase A2 (sPLA(2)-IIA) of mammalian species is unique among the many structurally and functionally related mammalian sPLA(2) in their high net positive charge and potent (nM) antibacterial activity. Toward the Gram-positive bacteria tested thus far, the global cationic properties of sPLA(2)-IIA are necessary for optimal binding to intact bacteria and penetration of the multi-layered thick cell wall, but not for the degradation of membrane phospholipids that is essential for bacterial killing. Various Gram-positive bacterial species can differ as much as 1000-fold in sPLA(2)-IIA sensitivity despite similar intrinsic enzymatic activity of sPLA(2)-IIA toward the membrane phospholipids of various bacteria. d-alanylation of wall- and lipo-teichoic acids in Staphylococcus aureus and sortase function in Streptococcus pyogenes increase bacterial resistance to sPLA(2)-IIA by up to 100-fold apparently by affecting translocation of bound sPLA(2)-IIA to the cell membrane. Action of the sPLA(2)-IIA and other related sPLA(2) against Gram-negative bacteria is more dependent on cationic properties of the enzyme near the amino-terminus of the protein and collaboration with other host defense proteins that produce alterations of the unique Gram-negative bacterial outer membrane that normally represents a barrier to sPLA(2)-IIA action. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.
| S-EPMC4605856 | biostudies-literature