A novel phospholipase A2 is a core component of the typhoid toxin genetic islet.

S. Typhi, the cause of typhoid fever, is a bacterial pathogen of substantial global importance. Typhoid toxin is a secreted AB-type toxin that is a key S. Typhi virulence factor encoded within a 5-gene genetic islet. Four genes in this islet have well-defined roles in typhoid toxin biology, however the function of the fifth gene is unknown. Here, we investigate the function of this gene, which we name ttaP. We show that ttaP is co-transcribed with the typhoid toxin subunit cdtB, and we perform genomic analyses that indicate that TtaP is very highly conserved in typhoid toxin islets found in diverse salmonellae. We show that TtaP is a distant homolog of group XIV secreted phospholipase A2 (PLA2) enzymes, and experimentally demonstrate that TtaP is a bona fide PLA2. Sequence and structural analyses indicate that TtaP differs substantially from characterized PLA2s, and thus represents a novel class of PLA2. Secretion assays revealed that TtaP is neither co-secreted with typhoid toxin, nor is it required for toxin secretion. Although TtaP is a phospholipase that remains associated with the S. Typhi cell, assays that probed for altered cell envelope integrity failed to identify any differences between wild-type S. Typhi and a ttaP deletion strain. Collectively, this study identifies a biochemical activity for the lone uncharacterized typhoid toxin islet gene and lays the groundwork for exploring how this gene factors into S. Typhi pathogenesis. This study further identifies a novel class of PLA2, enzymes that have a wide range of industrial applications.

A novel sustainable photo/chemical magnetic nanomaterial effectively mitigates the allergenicity of phospholipase A2.

Reducing the allergenicity of edible insects is crucial for the comprehensive utilization of insect resources. Phospholipase A2 (PLA2) exists in various edible insects and mammalian tissues, which can cause serious allergic reactions. Herein, we constructed a magnetic nanocomposite with photo/chemical synergistic capability to mitigate the allergenicity of PLA2. The formation of prepared nanocomposite was systematically confirmed using various techniques. The nanocomposite exhibited uniform diameters, abundant functional groups, excellent magnetic capabilities. An effective photo/chemical method was established to reduce the allergenicity of PLA2 in vitro. The feasibility of the method was demonstrated through circular dichroism, fluorescence spectrum and IgE-binding analysis. The allergenicity and IgE-binding effect of PLA2 were significantly reduced due to conformational changes after nanomaterial treatment. These results demonstrate the sensitivity and effectiveness a strategy for reducing PLA2 allergenicity, providing a basis for development of nanomaterials to reduce the risk of novel food allergies in response to edible insect products.

Inhibitors and activators for myotoxic phospholipase A2-like toxins from snake venoms - A structural overview.

Snakebite envenomations result in acute and chronic physical and psychological health effects on their victims, leading to a substantial socio-economic burden in tropical and subtropical countries. Local necrosis is one of the serious effects caused by envenomation, primarily induced by snake venoms from the Viperidae family through the direct action of components collectively denominated as myotoxins, including the phopholipase A2-like (PLA2-like) toxins. Considering the limitations of antivenoms in preventing the rapid development of local tissue damage caused by envenomation, the use of small molecule therapeutics has been suggested as potential first-aid treatments or as adjuvants to antivenom therapy. In this review, we provide an overview of the structural interactions of molecules exhibiting inhibitory activity toward PLA2-like toxins. Additionally, we discuss the implications for the myotoxic mechanism of PLA2-like toxins and the molecules involved in their activation, highlighting key differences between activators and inhibitors. Finally, we integrate all these results to propose a classification of inhibitors into three different classes and five sub-classes. Taking into account the structural and affinity information, we compare the different inhibitors/ligands to gain a deeper understanding of the structural basis for the effective inhibition of PLA2-like toxins. By offering these insights, we aim to contribute to the search for new and efficient inhibitor molecules to complement and improve current therapy by conventional antivenoms.

Study on the anti-inflammatory mechanism of moxibustion in rheumatoid arthritis in rats based on phospholipaseA2 signaling inhibition by Annexin 1.

OBJECTIVE: To determine whether moxibustion had an anti-inflammatory effect on rheumatoid arthritis (RA) by regulating Annexin 1 expression and interfering with the phospholipaseA2 signaling pathway. METHODS: Thirty male Sprague-Dawley rats were randomly categorized into five groups (six rats per group): blank control (CON) group, RA model (RA) group, moxibustion (MOX) group, Annexin 1 lentiviral intervention (RNAi-Anxa1) group, and Annexin 1 lentiviral intervention + moxibustion (RNAi-Anxa1 + MOX) group. The rats in the RNAi-Anxa1 and the RNAi-Anxa1 + MOX groups were injected with the lentiviral vector-mediated RNAi-Anxa1 into the rat foot pad. An experimental RA rat model was established by injecting Freund's complete adjuvant (FCA) into the RA, MOX, RNAi-Anxa1, and RNAi-Anxa1 + MOX groups. Rats in the MOX and RNAi-Anxa1 + MOX groups received moxibustion treatment. After modeling, using moxibustion "Shenshu (BL23)" and "Zusanli (ST36)", each point is 5 times, bilateral alternating, once a day, 6 times for a course of treatment, between the courses of rest for a one day. A total of three treatment courses were conducted. Both bilateral pad thicknesses were measured using Vernier calipers on experimental days 1, 7, 14, 21, and 28. The expression of cPLA2α signaling in the synovium of diseased joints was observed using Western blot. The pathology of the rat ankle synovium was observed using hematoxylin-eosin (HE) staining. Interleukin (IL)-1ß, IL-10, prostaglandin E2 (PGE2), and leukotriene B4 (LTB4) were detected using enzyme-linked immunosorbent assay. RESULTS: Moxibustion increased the levels of Annexin 1 and decreased the inflammatory response in rats with RA. After increasing the expression of Annexin 1, the phosphorylated expression of cPLA2α was inhibited, the serum levels of IL-1ß, PGE2, and LTB4 decreased, and the level of IL-10 increased. In moxibustion treated RA rats after the Annexin 1 lentiviral intervention, the serum levels of IL-1ß, PGE2, LTB4, and IL-10 were almost unchanged. CONCLUSION: Moxibustion enhanced the negative regulation of the cPLA2α signaling pathway, increased the synovial Annexin 1 expression, inhibited the cPLA2α signaling pathway, indirectly inhibited the expression of downstream inflammatory factors, and played a role in reducing inflammation.

Exploring the protein profile and biological activity of Crotalus molossus venom against E. coli, P. aeruginosa and S. aureus bacteria and T47D breast carcinoma cells.

Mexico has the highest diversity of snake species in the world, following Australia when considering just venomous snakes. Specifically, in Sonora, the second largest state in the country, more than 15 highly venomous species occur, including the northern black-tailed rattlesnake (Crotalus molossus). This specie's venom has not been as thoroughly researched in contrast with other Mexican vipers, nevertheless some studies report its biological activity and even pharmacological potential with antibacterial and cytotoxic activity. In this study we identified the main protein components from a pool of C. molossus venom through a gel-free proteomics approach, reporting ∼140 proteins belonging to the SVMP (38.76%), PLA2 (28.75%), CTL (11.93%), SVSP (6.03%) and LAAO (5.67%) toxin families. To study its biological activities, we evaluated its hemolytic, antibacterial, and cytotoxic activity in red blood cells, Gram positive and negative bacteria and a luminal A breast carcinoma cell line (T47D), respectively, in vitro. We report that concentrations <100 µg/mL are potentially not hemolytic and reduced the bacteria viability of E. coli and S. aureus with an IC50 of 10.27 and 11.51 µg/mL, respectively. Finally, we determined the C. molossus venom as cytotoxic against the T47D breast carcinoma cell line, with an IC50 of 1.55 µg/mL. We suggest that the evaluated cytotoxicity was due to a high abundance of SVMPs and PLA2s, since it's been reported that they affect the extracellular matrix and membrane permeation. This may provide a useful tool for pharmaceutical screening in the future.

Exploration of the pearl millet phospholipase gene family to identify potential candidates for grain quality traits.

BACKGROUND: Phospholipases constitute a diverse category of enzymes responsible for the breakdown of phospholipids. Their involvement in signal transduction with a pivotal role in plant development and stress responses is well documented. RESULTS: In the present investigation, a thorough genome-wide analysis revealed that the pearl millet genome contains at least 44 phospholipase genes distributed across its 7 chromosomes, with chromosome one harbouring the highest number of these genes. The synteny analysis suggested a close genetic relationship of pearl millet phospholipases with that of foxtail millet and sorghum. All identified genes were examined to unravel their gene structures, protein attributes, cis-regulatory elements, and expression patterns in two pearl millet genotypes contrasting for rancidity. All the phospholipases have a high alpha-helix content and distorted regions within the predicted secondary structures. Moreover, many of these enzymes possess binding sites for both metal and non-metal ligands. Additionally, the putative promoter regions associated with these genes exhibit multiple copies of cis-elements specifically responsive to biotic and abiotic stress factors and signaling molecules. The transcriptional profiling of 44 phospholipase genes in two genotypes contrasting for rancidity across six key tissues during pearl millet growth revealed a predominant expression in grains, followed by seed coat and endosperm. Specifically, the genes PgPLD-alpha1-1, PgPLD-alpha1-5, PgPLD-delta1-7a, PgPLA1-II-1a, and PgPLD-delta1-2a exhibited notable expression in grains of both the genotypes while showing negligible expression in the other five tissues. The sequence alignment of putative promoters revealed several variations including SNPs and InDels. These variations resulted in modifications to the corresponding cis-acting elements, forming distinct transcription factor binding sites suggesting the transcriptional-level regulation for these five genes in pearl millet. CONCLUSIONS: The current study utilized a genome-wide computational analysis to characterize the phospholipase gene family in pearl millet. A comprehensive expression profile of 44 phospholipases led to the identification of five grain-specific candidates. This underscores a potential role for at least these five genes in grain quality traits including the regulation of rancidity in pearl millet. Therefore, this study marks the first exploration highlighting the possible impact of phospholipases towards enhancing agronomic traits in pearl millet.

PLA2-MjTX-II from Bothrops moojeni snake venom exhibits antimetastatic and antiangiogenic effects on human lung cancer cells.

Phospholipases A2 (PLA2s) from snake venom possess antitumor and antiangiogenic properties. In this study, we evaluated the antimetastatic and antiangiogenic effects of MjTX-II, a Lys49 PLA2 isolated from Bothrops moojeni venom, on lung cancer and endothelial cells. Using in vitro and ex vivo approaches, we demonstrated that MjTX-II reduced cell proliferation and inhibited fundamental processes for lung cancer cells (A549) growth and metastasis, such as adhesion, migration, invasion, and actin cytoskeleton decrease, without significantly interfering with non-tumorigenic lung cells (BEAS-2B). Furthermore, MjTX-II caused cell cycle alterations, increased reactive oxygen species production, modulated the expression of pro- and antiangiogenic genes, and decreased vascular endothelial growth factor (VEGF) expression in HUVECs. Finally, MjTX-II inhibited ex vivo angiogenesis processes in an aortic ring model. Therefore, we conclude that MjTX-II exhibits antimetastatic and antiangiogenic effects in vitro and ex vivo and represents a molecule that hold promise as a pharmacological model for antitumor therapy.

Internalized ß2-Adrenergic Receptors Oppose PLC-Dependent Hypertrophic Signaling.

BACKGROUND: Chronically elevated neurohumoral drive, and particularly elevated adrenergic tone leading to ß-adrenergic receptor (ß-AR) overstimulation in cardiac myocytes, is a key mechanism involved in the progression of heart failure. ß1-AR (ß1-adrenergic receptor) and ß2-ARs (ß2-adrenergic receptor) are the 2 major subtypes of ß-ARs present in the human heart; however, they elicit different or even opposite effects on cardiac function and hypertrophy. For example, chronic activation of ß1-ARs drives detrimental cardiac remodeling while ß2-AR signaling is protective. The underlying molecular mechanisms for cardiac protection through ß2-ARs remain unclear. METHODS: ß2-AR signaling mechanisms were studied in isolated neonatal rat ventricular myocytes and adult mouse ventricular myocytes using live cell imaging and Western blotting methods. Isolated myocytes and mice were used to examine the roles of ß2-AR signaling mechanisms in the regulation of cardiac hypertrophy. RESULTS: Here, we show that ß2-AR activation protects against hypertrophy through inhibition of phospholipaseCε signaling at the Golgi apparatus. The mechanism for ß2-AR-mediated phospholipase C inhibition requires internalization of ß2-AR, activation of Gi and Gßγ subunit signaling at endosome and ERK (extracellular regulated kinase) activation. This pathway inhibits both angiotensin II and Golgi-ß1-AR-mediated stimulation of phosphoinositide hydrolysis at the Golgi apparatus ultimately resulting in decreased PKD (protein kinase D) and histone deacetylase 5 phosphorylation and protection against cardiac hypertrophy. CONCLUSIONS: This reveals a mechanism for ß2-AR antagonism of the phospholipase Cε pathway that may contribute to the known protective effects of ß2-AR signaling on the development of heart failure.

Alterations in salivary biomarkers in relation to periodontal health and obesity among Hong Kong adolescents.

OBJECTIVES: To explore the association among salivary biomarkers, periodontal inflammation, and adiposity status in adolescents. METHODS: This study included 180 Hong Kong adolescents aged 12-15 years. Anthropometric measurements including central obesity surrogate, waist-to-height ratio (WHtR), and dental examinations were conducted. The participants were classified into four groups as follows: with normal WHtR and less extensive periodontal inflammation (NW+LP); with high WHtR and less extensive periodontal inflammation (HW+LP); with normal WHtR and more extensive periodontal inflammation (NW+P); and with high WHtR and more extensive periodontal inflammation (HW+P). Saliva were collected to measure salivary physicochemical parameters, total bacterial load, and levels of protein biomarkers including secretory phospholipase A2 group IIA (sPLA2-IIA) and interleukin-6 (IL-6). Data were analysed by Kruskal-Wallis test and Spearman correlation coefficient. RESULTS: Salivary IL-6 levels and sPLA2-IIA and IL-6 output differed significantly between groups (P = 0.041, 0.027, and 0.043, respectively). The NW+P group had significantly higher salivary IL-6 output than the NW+LP group (P = 0.034) and significantly lower salivary sPLA2-IIA output than the HW+LP group (P = 0.038). Salivary IL-6 levels were negatively correlated with the number of sextants with healthy gingivae and positively correlated with salivary sPLA2-IIA levels in participants with normal WHtR. Salivary sPLA2-IIA levels were negatively correlated with total salivary bacterial load in participants with high WHtR. CONCLUSIONS: Salivary IL-6 levels were associated with the extent of periodontal inflammation in participants with normal WHtR but not in those with high WHtR. Adolescents with different adiposity status may have different mechanisms of periodontal inflammation. CLINICAL SIGNIFICANCE: Investigating salivary biomarkers of periodontal health holds potential benefits in identifying individuals at risk and customizing oral health promotion strategies for individuals with varying levels of adiposity, even as early as adolescence.

Enzyme-responsive liposomes for controlled drug release.

Compared to other nanovectors, liposomes exhibit unique advantages, such as good biosafety and high drug-loading capacity. However, slow drug release from conventional liposomes makes most payloads unavailable, restricting the therapeutic efficacy. Therefore, in the last ∼20 years, enzyme-responsive liposomes have been extensively investigated, which liberate drugs under the stimulation of enzymes overexpressed at disease sites. In this review, we elaborate on the research progress on enzyme-responsive liposomes. The involved enzymes mainly include phospholipases, particularly phospholipase A2, matrix metalloproteinases, cathepsins, and esterases. These enzymes can cleave ester bonds or specific peptide sequences incorporated in the liposomes for controlled drug release by disrupting the primary structure of liposomes, detaching protective polyethylene glycol shells, or activating liposome-associated prodrugs. Despite decades of efforts, there are still a lack marketed products of enzyme-responsive liposomes. Therefore, more efforts should be made to improve the safety and effectiveness of enzyme-responsive liposomes and address the issues associated with production scale-up.

Nuclear Phospholipids and Signaling: An Update of the Story.

In the last three decades, the presence of phospholipids in the nucleus has been shown and thoroughly investigated. A considerable amount of interest has been raised about nuclear inositol lipids, mainly because of their role in signaling acting. Here, we review the main issues of nuclear phospholipid localization and the role of nuclear inositol lipids and their related enzymes in cellular signaling, both in physiological and pathological conditions.

Characterization of Lysophospholipase D Activity in Mammalian Cell Membranes.

Lysophosphatidic acid (LPA) is a lipid mediator that binds to G-protein-coupled receptors, eliciting a wide variety of responses in mammalian cells. Lyso-phospholipids generated via phospholipase A2 (PLA2) can be converted to LPA by a lysophospholipase D (lyso-PLD). Secreted lyso-PLDs have been studied in more detail than membrane-localized lyso-PLDs. This study utilized in vitro enzyme assays with fluorescent substrates to examine LPA generation in membranes from multiple mammalian cell lines (PC12, rat pheochromocytoma; A7r5, rat vascular smooth muscle; Rat-1, rat fibroblast; PC-3, human prostate carcinoma; and SKOV-3 and OVCAR-3, human ovarian carcinoma). The results show that membranes contain a lyso-PLD activity that generates LPA from a fluorescent alkyl-lyso-phosphatidylcholine, as well as from naturally occurring acyl-linked lysophospholipids. Membrane lyso-PLD and PLD activities were distinguished by multiple criteria, including lack of effect of PLD2 over-expression on lyso-PLD activity and differential sensitivities to vanadate (PLD inhibitor) and iodate (lyso-PLD inhibitor). Based on several lines of evidence, including siRNA knockdown, membrane lyso-PLD is distinct from autotaxin, a secreted lyso-PLD. PC-3 cells express GDE4 and GDE7, recently described lyso-PLDs that localize to membranes. These findings demonstrate that membrane-associated lyso-D activity, expressed by multiple mammalian cell lines, can contribute to LPA production.

TR(i)P Goes On: Auxiliary TRP Channel Subunits?

Transient receptor potential (TRP) cation channels are a diverse family of channels whose members play prominent roles as cellular sensors and effectors. The important role of TRP channels (and mechanosensitive piezo channels) in the complex interaction of our senses with the environment was underlined by the award of the Nobel Prize in Physiology or Medicine to 2 pioneers in this field, David Julius and Ardem Patapoutian. There are many competent and comprehensive reviews on many aspects of the TRP channels, and there is no intention to expand on them. Rather, after an introduction to the nomenclature, the molecular architecture of native TRP channel/protein complexes in vivo will be summarized using TRP channels of the canonical transient receptor potential subfamily as an example. This molecular architecture provides the basis for the signatures of native canonical transient receptor potential currents and their control by endogenous modulators and potential drugs.

Phytochemical characterization and phospholipase A2 inhibitory effect of Vitex negundo L. root extracts.

ETHNOPHARMACOLOGICAL RELEVANCE: Snake bites are a critical health issue in many parts of the world particularly in Asian countries lacking efficient health facilities in rural areas. Cobra is the most common snake type in Asia and is responsible for a large number of mortalities particularly in rural areas. Plants are usually considered the most effective and easy-to-approach treatment for snake bites in rural areas of various countries. Vitex negundo L. is an important medicinal plant traditionally used to treat snake bite envenomation in many countries of Asia. AIM OF THE STUDY: From literature survey of plants traditionally used in the treatment of snake bites in Asian countries including India, Pakistan and Sri Lanka, roots of V. negundo were selected for the present study. Anti-snake venom potential of its roots was assessed through various in vitro assays targeting the phospholipase A2 enzyme. MATERIALS AND METHODS: V. negundo roots were sequentially extracted in different organic solvents to get fractions and in methanol to get total extract. The extracts were evaluated for phospholipase A2 (PLA2) inhibitory potential through inhibition of venom-induced hemolysis, ADP-induced platelet aggregation, PLA2-induced fatty acid hydrolysis and anticoagulant effect of cobra venom. Antioxidant power was determined using DPPH and superoxide radical scavenging assays. GC-MS and HPLC analysis was performed for the total methanol extract. RESULTS: Strong PLA2 inhibitory effect was observed for all the extracts. The ethyl acetate, acetone and methanol fractions significantly inhibited toxic effects of cobra venom under in vitro conditions. Radical scavenging potential of these fractions was also significantly high as compared to non-polar fractions in both DPPH and superoxide scavenging assays. Phytochemical analysis indicated high phenolic and flavonoid contents in these fractions. GC-MS and HPLC analysis of total methanol extract confirmed the presence of bis(2-ethylhexyl) phthalate, phenol, o-Guaiacol, palmitic acid-methyl ester, methyl stearate, quercetin and kaempferol in the plant. CONCLUSION: The study concluded that the roots of V. negundo, particularly their polar extracts, have strong PLA2 inhibitory effect against cobra venom confirming their traditional use to manage snake bites. The roots of this plant can be further studied for isolation of plant-based antisera.

Tools and mechanisms of vacuolar escape leading to host egress in Legionella pneumophila infection: Emphasis on bacterial phospholipases.

The phenomenon of host cell escape exhibited by intracellular pathogens is a remarkably versatile occurrence, capable of unfolding through lytic or non-lytic pathways. Among these pathogens, the bacterium Legionella pneumophila stands out, having adopted a diverse spectrum of strategies to disengage from their host cells. A pivotal juncture that predates most of these host cell escape modalities is the initial escape from the intracellular compartment. This critical step is increasingly supported by evidence suggesting the involvement of several secreted pathogen effectors, including lytic proteins. In this intricate landscape, L. pneumophila emerges as a focal point for research, particularly concerning secreted phospholipases. While nestled within its replicative vacuole, the bacterium deftly employs both its type II (Lsp) and type IVB (Dot/Icm) secretion systems to convey phospholipases into either the phagosomal lumen or the host cell cytoplasm. Its repertoire encompasses numerous phospholipases A (PLA), including three enzymes-PlaA, PlaC, and PlaD-bearing the GDSL motif. Additionally, there are 11 patatin-like phospholipases A as well as PlaB. Furthermore, the bacterium harbors three extracellular phospholipases C (PLCs) and one phospholipase D. Within this comprehensive review, we undertake an exploration of the pivotal role played by phospholipases in the broader context of phagosomal and host cell egress. Moreover, we embark on a detailed journey to unravel the established and potential functions of the secreted phospholipases of L. pneumophila in orchestrating this indispensable process.

Lipoprotein-associated phospholipase A 2 and cognitive impairment in patients with cerebral small vessel disease / 国际脑血管病杂志

In recent years, the incidence of cerebral small vessel disease (CSVD) has been increasing with the aging of the population, and the cognitive impairment caused by it has brought huge burden to patients and their families. As a novel inflammatory biomarker, lipoprotein-associated phospholipase A 2 (Lp-PLA 2) directly participates in the pathogenesis of cognitive impairment in patients with CSVD by regulating circulatory vascular injury and neuroinflammation, and is expected to become a predictive indicator and therapeutic target for CSVD.

PLA2-MjTX-II from Bothrops moojeni snake venom exhibits antimetastatic and antiangiogenic effects on human lung cancer cells

Phospholipases A2 (PLA2s) from snake venom possess antitumor and antiangiogenic properties. In this study, we evaluated the antimetastatic and antiangiogenic effects of MjTX-II, a Lys49 PLA2 isolated from Bothrops moojeni venom, on lung cancer and endothelial cells. Using in vitro and ex vivo approaches, we demonstrated that MjTX-II reduced cell proliferation and inhibited fundamental processes for lung cancer cells (A549) growth and metastasis, such as adhesion, migration, invasion, and actin cytoskeleton decrease, without significantly interfering with non-tumorigenic lung cells (BEAS-2B). Furthermore, MjTX-II caused cell cycle alterations, increased reactive oxygen species production, modulated the expression of pro- and antiangiogenic genes, and decreased vascular endothelial growth factor (VEGF) expression in HUVECs. Finally, MjTX-II inhibited ex vivo angiogenesis processes in an aortic ring model. Therefore, we conclude that MjTX-II exhibits antimetastatic and antiangiogenic effects in vitro and ex vivo and represents a molecule that hold promise as a pharmacological model for antitumor therapy.

Phosphatidic acid signaling and function in nuclei.

Membrane lipidomes are dynamic and their changes generate lipid mediators affecting various biological processes. Phosphatidic acid (PA) has emerged as an important class of lipid mediators involved in a wide range of cellular and physiological responses in plants, animals, and microbes. The regulatory functions of PA have been studied primarily outside the nuclei, but an increasing number of recent studies indicates that some of the PA effects result from its action in nuclei. PA levels in nuclei are dynamic in response to stimuli. Changes in nuclear PA levels can result from activities of enzymes associated with nuclei and/or from movements of PA generated extranuclearly. PA has also been found to interact with proteins involved in nuclear functions, such as transcription factors and proteins undergoing nuclear translocation in response to stimuli. The nuclear action of PA affects various aspects of plant growth, development, and response to stress and environmental changes.

Phospholipases A and Lysophospholipases in protozoan parasites.

Phospholipases (PLs) and Lysophospholipases (LysoPLs) are a diverse group of esterases responsible for phospholipid or lysophospholipid hydrolysis. They are involved in several biological processes, including lipid catabolism, modulation of the immune response and membrane maintenance. PLs are classified depending on their site of hydrolysis as PLA1, PLA2, PLC and PLD. In many pathogenic microorganisms, from bacteria to fungi, PLAs and LysoPLs have been described as critical virulence and/or pathogenicity factors. In protozoan parasites, a group containing major human and animal pathogens, growing literature show that PLAs and LysoPLs are also involved in the host infection. Their ubiquitous presence and role in host-pathogen interactions make them particularly interesting to study. In this review, we summarize the literature on PLAs and LysoPLs in several protozoan parasites of medical relevance, and discuss the growing interest for them as potential drug and vaccine targets.

Cellular Export Fate of Liposomal Spherical Nucleic Acids.

Liposomal spherical nucleic acids (LSNAs) are useful structures for oligonucleotide-based cell modulation because of their biocompatibility and ability to readily enter cells without transfection agents. Understanding LSNA trafficking is key to developing applications, but while much is understood about LSNA cell uptake, little is known about their export fate. Here, we study LSNA export through pulse-chase studies with fluorophore-labeled LSNAs. Our findings show that the components of LSNAs are differentially exported by cells, with the phospholipids showing 90-100% export and the oligonucleotides showing 30-45% export over 24 h in RAW264.7 macrophages. Despite the increase in the level of uptake of LSNAs, these percentages are not significantly influenced by whether the materials are taken up as LSNAs or as the individual components. The exported oligonucleotide material consists of a full-length oligonucleotide with the phospholipid anchor modified by loss of a fatty acid. The exported liposome-derived phospholipids also had a fatty acid removed. Moreover, the exported oligonucleotide-lysophospholipid conjugates retain immunostimulatory potential. These findings indicate that after cellular entry LSNAs are degraded into lysophospholipids, something to which they are susceptible due to the presence of hydrolyzable ester bonds. The export percentage of the resultant materials over 24 h is independent of the amount imported, such that greater initial import leads to a similar fold increase in exported material. This work therefore reveals an intracellular feature of LSNAs and shows that the enhanced uptake achieved with LSNAs can be exploited to maximize the amount of material subsequently exported, suggesting avenues for leveraging pharmacologic effects from exported LSNA components.