Lysophosphatidic Acid Synthesis Research Articles

Multi-Omics Analysis by Machine Learning Identified Lysophosphatidic Acid as a Biomarker and Therapeutic Target for Porcine Reproductive and Respiratory Syndrome.

As a significant infectious disease in livestock, porcine reproductive and respiratory syndrome (PRRS) imposes substantial economic losses on the swine industry. Identification of diagnostic markers and therapeutic targets has been a focal challenge in PPRS prevention and control. By integrating metabolomic and lipidomic serum analyses of clinical pig cohorts through a machine learning approach with in vivo and in vitro infection models, lysophosphatidic acid (LPA) is discovered as a serum metabolic biomarker for PRRS virus (PRRSV) clinical diagnosis. PRRSV promoted LPA synthesis by upregulating the autotaxin expression, which causes innate immunosuppression by dampening the retinoic acid-inducible gene I (RIG-I) and type I interferon responses, leading to enhanced virus replication. Targeting LPA demonstrated protection against virus infection and associated disease outcomes in infected pigs, indicating that LPA is a novel antiviral target against PRRSV. This study lays a foundation for clinical prevention and control of PRRSV infections.

Lysophosphatidic acid and itsreceptors: Role in bronchial asthma pathogenesis

Lysophosphatidic acid (LPA) is a biologically active lipid mediator that regulates a number ofsignaling pathways involved in the pathogenesis of bronchial asthma. Attention to studying the relationship of LPA with LPA receptors (LPARs) and ion channels with transient receptor potential (TRP) is caused by their role in the initiation and development of bronchial obstruction, which suggests the development of new effective strategies for the treatment of bronchial asthma through blocking LPA synthesis and/or regulation of the activity of the ligand-receptor relationship.The aim of the review. To summarize ideas on the role of lysophosphatidic acid and its receptors in the pathogenesis of bronchial asthma based on the analysis of articles published in English in 2020–2023 from the PubMed database.Conclusion. The review summarizes recent literature data on the chemical structure, biosynthetic pathways and LPA receptors. It presents the information on the role of LPA, LPARs andTRP channels inthepathogenesis of bronchial asthma; summarizes the bronchial asthma therapeutic strategies targeting LPA, LPARs, andTRP channels. The review highlights not only a new perspective on understanding the mechanisms of initiation of asthmatic reactions, but also possible ways to manage them at the stage of correction of their development.

Glycerol-3-phosphate acyltransferase 3-mediated lipid droplets accumulation confers chemoresistance of colorectal cancer.

Colorectal cancer (CRC) is the third most common malignancy worldwide. It is well known that lipid metabolism reprogramming contributes to the tumor progression. However, the lipid metabolic alterations and potential remodeling mechanism underlying the chemoresistance of CRC remain largely unclear. In this study, we compared the gene expression profiles of chemoresistant versus control CRC cells from the GEO database and identified a key factor, Glycerol-3-phosphate acyltransferase 3 (GPAT3), that promotes lipid droplet (LD) production and confers chemoresistance of CRC. With applying of HPLC-MS and molecular dynamics simulation, we also demonstrated that the activity of lysophosphatidic acid synthesis by GPAT3 was dependent on its acetylation at K316 site. In particular, GPAT3-mediated LD accumulation inhibited immunogenic cell death of tumor, and thus facilitated CD8+ T-cell exhaustion and malignant progression in mouse xenografts and hepatic-metastasis tumors in CRC patients. High GPAT3 expression turned CRC cells into nonimmunogenic cells after (Oxaliplatin) Oxa treatment, which was supported by a decrease in cytotoxic IFN-γ release and CD8+ T-cell exhaustion. In conclusion, these findings revealed the role of GPAT3-associated LD accumulation, which conferred a malignant phenotype (chemoresistance) and regulated the tumor microenvironment of CRC. These results suggest that GPAT3 is a potential target to enhance CRC chemosensitivity and develop novel therapeutic interventions.

Lysophosphatidic acid contributes to myocardial ischemia/reperfusion injury by activating TRPV1 in spinal cord.

Lysophosphatidic acid (LPA) is a bioactive phospholipid that plays a crucial role in cardiovascular diseases. Here, we question whether LPA contributes to myocardial ischemia/reperfusion (I/R) injury by acting on transient receptor potential vanilloid 1 (TRPV1) in spinal cord. By ligating the left coronary artery to establish an in vivo I/R mouse model, we observed a 1.57-fold increase in LPA level in the cerebrospinal fluid (CSF). The I/R-elevated CSF LPA levels were reduced by HA130, an LPA synthesis inhibitor, compared to vehicle treatment (4.74 ± 0.34 vs. 6.46 ± 0.94μg/mL, p = 0.0014). Myocardial infarct size was reduced by HA130 treatment compared to the vehicle group (26 ± 8% vs. 46 ± 8%, p = 0.0001). To block the interaction of LPA with TRPV1 at the K710 site, we generated a K710N knock-in mouse model. The TRPV1K710N mice were resistant to LPA-induced myocardial injury, showing a smaller infarct size relative to TRPV1WT mice (28 ± 4% vs. 60 ± 7%, p < 0.0001). Additionally, a sequence-specific TRPV1 peptide targeting the K710 region produced similar protective effects against LPA-induced myocardial injury. Blocking the K710 region through K710N mutation or TRPV1 peptide resulted in reduced neuropeptides release and decreased activity of cardiac sensory neurons, leading to a decrease in cardiac norepinephrine concentration and the restoration of intramyocardial pro-survival signaling, namely protein kinase B/extracellular regulated kinase/glycogen synthase kinase-3β pathway. These findings suggest that the elevation of CSF LPA is strongly associated with myocardial I/R injury. Moreover, inhibiting the interaction of LPA with TRPV1 by blocking the K710 region uncovers a novel strategy for preventing myocardial ischemic injury.

MTCH2 cooperates with MFN2 and lysophosphatidic acid synthesis to sustain mitochondrial fusion

Fusion of the outer mitochondrial membrane (OMM) is regulated by mitofusin 1 (MFN1) and 2 (MFN2), yet the differential contribution of each of these proteins is less understood. Mitochondrial carrier homolog 2 (MTCH2) also plays a role in mitochondrial fusion, but its exact function remains unresolved. MTCH2 overexpression enforces MFN2-independent mitochondrial fusion, proposedly by modulating the phospholipid lysophosphatidic acid (LPA), which is synthesized by glycerol-phosphate acyl transferases (GPATs) in the endoplasmic reticulum (ER) and the OMM. Here we report that MTCH2 requires MFN1 to enforce mitochondrial fusion and that fragmentation caused by loss of MTCH2 can be specifically counterbalanced by overexpression of MFN2 but not MFN1, partially independent of its GTPase activity and mitochondrial localization. Pharmacological inhibition of GPATs (GPATi) or silencing ER-resident GPATs suppresses MFN2’s ability to compensate for the loss of MTCH2. Loss of either MTCH2, MFN2, or GPATi does not impair stress-induced mitochondrial fusion, whereas the combined loss of MTCH2 and GPATi or the combined loss of MTCH2 and MFN2 does. Taken together, we unmask two cooperative mechanisms that sustain mitochondrial fusion.

Abstract 13046: Lysophosphatidic Acid Activates Spinal TRPV1 Signaling and Contributes to Myocardial Ischemia/Reperfusion Injury

Introduction: Lysophosphatidic acid (LPA) has been shown to directly activate transient receptor potential vanilloid 1 (TRPV1) on primary nociceptors via the binding site of K710 to produce acute pain. However, it is unclear whether LPA participates in myocardial ischemia/reperfusion (I/R) injury by activating TRPV1 receptors. Hypothesis: We hypothesize that LPA contributes to myocardial I/R injury by acting on TRPV1 receptors in the spinal cord, and that blocking the interaction between LPA and TRPV1 could exert cardioprotective effects. Methods: Wild type male C57BL/6 mice underwent myocardial I/R injury, and LPA levels in cerebrospinal fluid (CSF) were measured. LPA synthesis inhibitor HA-130 or exogenous LPA were intrathecally administrated during myocardial ischemia. Additionally, CRISPR/Cas-9 edited TRPV1K710N knock-in mice and a peptide V1-Cal targeting the K710 region were utilized to block the interaction of LPA with TRPV1. Results: The levels of LPA in CSF of the I/R group were found to be 1.5-fold higher than those of the sham group (Fig.1B, p=0.0001). Intrathecal administration of HA130 reduced infarct size (Fig.1C, p=0.0021) and CSF LPA levels (Fig.1D, p=0.0018). The CSF LPA levels were positively correlated with infarct size (Fig.1E, p&lt;0.0001). Intrathecal administration of LPA caused a 1.4-fold rise in infarct size relative to I/R group in wild type mice (Fig.1F, p&lt;0.0001), but not in TRPV1K710N mice (Fig.1F, p&gt;0.9999). LPA treatment enhanced the activation of spinal TRPV1 receptors following I/R injury in wild type mice, but not in TRPV1K710N mice (Fig.1 G-I). Further, the V1-Cal peptide reduced myocardial I/R injury, as well as the protein levels of TRPV1 and pTRPV1 in spinal cord (Fig.1 J-M). Conclusions: Our results suggest that LPA activates spinal TRPV1 signaling and contributes to myocardial I/R injury. Blockade of the interaction between LPA and TRPV1 in spinal cord may be a promising therapeutic approach for myocardial ischemic injury.

GPAM mediated lysophosphatidic acid synthesis regulates mitochondrial dynamics in acute myeloid leukemia.

Metabolic alterations, especially in the mitochondria, play important roles in several kinds of cancers, including acute myeloid leukemia (AML). However, AML-specific molecular mechanisms that regulate mitochondrial dynamics remain elusive. Through the metabolite screening comparing CD34+ AML cells and healthy hematopoietic stem/progenitor cells, we identified enhanced lysophosphatidic acid (LPA) synthesis activity in AML. LPA is synthesized from glycerol-3-phosphate by glycerol-3-phosphate acyltransferases (GPATs), rate-limiting enzymes of the LPA synthesis pathway. Among the four isozymes of GPATs, glycerol-3-phosphate acyltransferases, mitochondrial (GPAM) was highly expressed in AML cells, and the inhibition of LPA synthesis by silencing GPAM or FSG67 (a GPAM-inhibitor) significantly impaired AML propagation through the induction of mitochondrial fission, resulting in the suppression of oxidative phosphorylation and the elevation of reactive oxygen species. Notably, inhibition of this metabolic synthesis pathway by FSG67 administration did not affect normal human hematopoiesis in vivo. Therefore, the GPAM-mediated LPA synthesis pathway from G3P represents a critical metabolic mechanism that specifically regulates mitochondrial dynamics in human AML, and GPAM is a promising potential therapeutic target.

GPAT3 regulates the synthesis of lipid intermediate LPA and exacerbates Kupffer cell inflammation mediated by the ERK signaling pathway

In the process of inflammatory activation, macrophages exhibit lipid metabolism disorders and accumulate lipid droplets. Kupffer cells (KCs) are the resident hepatic macrophage with critical defense functions in the pathogenesis of several types of liver disease. How dysregulated lipid metabolism contributes to perturbed KCs functions remains elusive. Here we report that glycerol-3-phosphate acyltransferase 3 (GPAT3) plays a key role in KCs inflammation response. Our findings indicate that lipopolysaccharide (LPS)-mediated inflammatory activation markedly increased lipid droplets (LDs) accumulation in KCs. This increase could be attributed to significantly up-regulated GPAT3. The loss of GPAT3 function obviously reduced KCs inflammation reaction both in vivo and in vitro, and was accompanied by improved mitochondrial function and decreased production of lysophosphatidic acid (LPA), in turn inhibiting extracellular regulated protein kinases (ERK) signaling pathway. Overall, this study highlights the role of GPAT3 in inflammatory activation of KCs and could thus be a potential therapeutic target for the treatment of inflammation-related liver disease.

Decrease in serum levels of autotaxin in COVID-19 patients

Introduction In order to identify therapeutic targets in Coronavirus disease 2019 (COVID-19), it is important to identify molecules involved in the biological responses that are modulated in COVID-19. Lysophosphatidic acids (LPAs) are involved in the pulmonary inflammation and fibrosis are one of the candidate molecules. The aim of this study was to evaluate the association between the serum levels of autotaxin (ATX), which are enzymes involved in the synthesis of lysophosphatidic acids. Material and methods We enrolled 134 subjects with COVID-19 and 58 normal healthy subjects for the study. We measured serum ATX levels longitudinally in COVID-19 patients and investigated the time course and the association with severity and clinical parameters. Results The serum ATX levels were reduced in all patients with COVID-19, irrespective of the disease severity, and were negatively associated with the serum CRP, D-dimer, and anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody levels. Discussion Considering the biological properties of LPAs in the pulmonary inflammation and fibrosis, modulation of ATX might be compensatory biological responses to suppress immunological overreaction especially in the lung, which is an important underlying mechanism for the mortality of the disease. Conclusions COVID-19 patients showed a decrease in the serum levels of ATX, irrespective of the disease severity. Key Messages Autotaxin (ATX) is an enzyme involved in the synthesis of lysophosphatidic acid (LPA), which has been reported to be involved in pulmonary inflammation and fibrosis. Patients with COVID-19 show decrease in the serum levels of ATX. Modulation of ATX might be compensatory biological responses to suppress immunological overreaction.

Different Profiles of the Triad of Lysophosphatidylcholine, Lysophosphatidic Acid, and Autotaxin in Patients with Neuropathic Pain Diseases: a Preliminary Observational Study.

The mechanisms underlying neuropathic pain remain unclear. Lysophosphatidic acid (LPA) is a bioactive phospholipid derived mainly from lysophosphatidylcholine (LPC) by extracellular autotaxin (ATX), and has attracted attention as a candidate biomarker of neuropathic pain. We aimed to investigate the levels of LPA, LPC, and ATX in patients with lumbar spinal canal stenosis (LSCS) or other neuropathic pain diseases, and to distinguish the underlying mechanism of LSCS from other neuropathic pain conditions. Furthermore, the levels of phosphorylated neurofilament heavy chain (pNF-H), an objective surrogate marker of axonal damage, were also measured. Cerebrospinal fluid (CSF) samples were obtained from 56 patients with LSCS (n = 31) and various etiologies other than LSCS (n = 25). Patients with LSCS complained of pain intensity comparable to that of patients without LSCS. The LPA levels were significantly higher in patients with LSCS than in non-LSCS patients, while the ATX levels were significantly lower. However, the differences in LPC and pNF-H levels between the two patient groups were not significant. The LPA/LPC ratio was significantly higher in the LSCS group. Notably, the difference in LPA between the two groups diminished in the analysis of covariance (ANCOVA) with ATX as a covariate. Thus, it helped to reveal that LPA synthesis in patients with LSCS depends more efficiently on ATX than in non-LSCS neuropathic pain patients with other etiologies. Our findings further suggest that the triad of LPA, LPC, and ATX in LSCS may contribute to the development and maintenance of neuropathic pain in a manner different from non-LSCS neuropathic conditions.

AgRP neurons control feeding behaviour at cortical synapses via peripherally derived lysophospholipids.

Phospholipid levels are influenced by peripheral metabolism. Within the central nervous system, synaptic phospholipids regulate glutamatergic transmission and cortical excitability. Whether changes in peripheral metabolism affect brain lipid levels and cortical excitability remains unknown. Here, we show that levels of lysophosphatidic acid (LPA) species in the blood and cerebrospinal fluid are elevated after overnight fasting and lead to higher cortical excitability. LPA-related cortical excitability increases fasting-induced hyperphagia, and is decreased following inhibition of LPA synthesis. Mice expressing a human mutation (Prg-1R346T) leading to higher synaptic lipid-mediated cortical excitability display increased fasting-induced hyperphagia. Accordingly, human subjects with this mutation have higher body mass index and prevalence of type 2 diabetes. We further show that the effects of LPA following fasting are under the control of hypothalamic agouti-related peptide (AgRP) neurons. Depletion of AgRP-expressing cells in adult mice decreases fasting-induced elevation of circulating LPAs, as well as cortical excitability, while blunting hyperphagia. These findings reveal a direct influence of circulating LPAs under the control of hypothalamic AgRP neurons on cortical excitability, unmasking an alternative non-neuronal route by which the hypothalamus can exert a robust impact on the cortex and thereby affect food intake.

Abstract P773: Autotaxin and Lysophosphatidic Acid Impair Blood Brain Barrier and Mitochondria Following Ischemic Stroke

Introduction: Ischemic stroke is a leading cause of death and a serious cause of long-term disability in the US. r-TPA is the only treatment available for stroke. Only 5% of patients receive it, as others have the risk of intracerebral hemorrhage. Ischemic reperfusion (I/R) following stroke exacerbates the condition and initiates various molecular signals, ultimately interrupting blood-brain barrier BBB so, better therapy is in need. Lysophosphatidic acid (LPA) is a bioactive lipid regulating various essential cellular functions such as migration, proliferation, adhesion. Autotaxin (ATX) produces LPA, which then regulates through its six G-protein coupled receptors. Methods: Transient middle cerebral artery occlusion (MCAO) with 90 minutes of ischemia and 24 hours of reperfusion was used as a stroke model in mice. LPA was analyzed in plasma with mass spectrometry and in tissue with immunohistochemistry. AR-2 probe fluorescence measured ATX activity. Seahorse analyzer measured the mitochondrial bioenergetics in brain and mouse brain microvascular endothelial cells (MBMEC). Permeability was studied with Electric Cell Substrate Impedance System. Results: ATX was elevated in mRNA level with 1.7 fold increased activity following I/R. LPA showed a significant (P&lt;0.01) increase in the plasma of MCAO mice. LPA in the brain tissue of MCAO mice revealed an increased synthesis of LPA by ATX following I/R injury. Brain mitochondria isolated following I/R injury had significantly (P&lt;0.01) reduced the mitochondrial oxygen consumption rate (OCR). Permeability measured in MBMECs showed LPA treatment increases the permeability. Also, the protein levels of junctional proteins such as βcatenin, Claudin5, VEcadherin, and Zo1 were significantly (P&lt;0.05) decreased with LPA exposure. LPA, as a negative regulator of the BBB, caused permeability through LPA-LPAR1-ROCK dependent pathway. MBMECs show impaired mitochondrial function with decreased OCR and elevated glycolysis towards LPA treatment (P&lt;0.01). Conclusion: We have shown that LPA and its regulator enzyme ATX play a significant role in ischemic stroke, increasing BBB permeability, and elevating mitochondrial dysfunction. ATX inhibitors as therapy could improve the condition of stroke patients.

Alcohol Induced Oxidative Stress in neonatal Cardio myocytes

Alcohol Induced Oxidative Stress in neonatal Cardio myocytes

Autotaxin Implication in Cancer Metastasis and Autoimunne Disorders: Functional Implication of Binding Autotaxin to the Cell Surface.

Autotaxin (ATX) is an exoenzyme which, due to its unique lysophospholipase D activity, is responsible for the synthesis of lysophosphatidic acid (LPA). ATX activity is responsible for the concentration of LPA in the blood. ATX expression is increased in various types of cancers, including breast cancer, where it promotes metastasis. The expression of ATX is also remarkably increased under inflammatory conditions, particularly in the osteoarticular compartment, where it controls bone erosion. Biological actions of ATX are mediated by LPA. However, the phosphate head group of LPA is highly sensitive to degradation by the action of lipid phosphate phosphatases, resulting in LPA inactivation. This suggests that for efficient action, LPA requires protection, which is potentially achieved through docking to a carrier protein. Interestingly, recent reports suggest that ATX might act as a docking molecule for LPA and also support the concept that binding of ATX to the cell surface through its interaction with adhesive molecules (integrins, heparan sulfate proteoglycans) could facilitate a rapid route of delivering active LPA to its cell surface receptors. This new mechanism offers a new vision of how ATX/LPA works in cancer metastasis and inflammatory bone diseases, paving the way for new therapeutic developments.

Identification of GPAT1 As a Novel Therapeutic Target for Acute Leukemia By Inhibiting Leukemia Specific Metabolism

With the development of mass spectrometer technology, recent studies revealed the critical roles of cancer-specific metabolism for tumor propagation in several types of cancers. In leukemia, many studies have been conducted to elucidate a leukemia-specific metabolism, and several effective treatments such as IDH1/2 inhibitors targeting acute myeloid leukemia (AML) with IDH1/2 mutation have been developed. To identify the new metabolic pathways on which acute leukemia cells depend, we purified water-soluble metabolites from CD34+ hematopoietic stem and progenitor cells (HSPCs) of healthy donors, AML and acute lymphoblastic leukemia (ALL) patients, and we comprehensively measured 116 metabolites using mass spectrometer analysis. From this experiment, we found that the cellular content of glycerol 3-phosphate (G3P) in CD34+ AML and ALL cells was lower than that of normal CD34+ HSPCs. G3P is an intermediate metabolite in the glycolysis metabolic pathway and is utilized as a substrate for phospholipids synthesis. The initial and rate-limiting step of phospholipids synthesis is the synthesis of lysophosphatidic acid (LPA) from G3P and acyl-CoA mediated by glycerol 3-phosphate acyltransferases (GPATs). Since CD34+ acute leukemia cells contained significantly lower level of G3P, we hypothesized that leukemia cells actively consumed G3P and synthesized LPA by GPATs. GPATs are classified into four isoforms based on intracellular localization and substrate preference. GPAT1 and GPAT2 are mitochondrial GPATs that are localized to the mitochondrial outer membrane, but on the other hand, GPAT3 and GPAT4 are microsomal GPATs that are localized to the endoplasmic reticulum membrane, each encoded by independent genes. GPAT1 is identified as an essential gene for the growth of leukemia cells by RNAi screen analysis in the public database (DepMap). We found that CD34+ immature AML cells exhibited higher GPAT1 expression as compared to CD34- more differentiated AML cells and normal T cells. GPAT1 knockdown inhibited the proliferation of several acute leukemia cell lines including THP-1 and Kasumi-1 in vitro and in vivo. Moreover, a mitochondrial GPATs specific inhibitor (FSG67), which was originally developed as a drug to treat obesity and diabetes, suppressed the growth of the leukemia cell lines through the induction of G1 cell cycle arrest. Growth inhibition was rescued by exogenous administration of LPA, suggesting that the synthetic activity mediated by mitochondrial GPATs should be required for acute leukemia growth. Furthermore, FSG67 induced the apoptosis of leukemia cells derived from AML and ALL patients without affecting normal CD34+ HSPCs at least in vitro. We also confirmed that the injection of FSG67 resulted in the suppression of AML and ALL propagation in vivo using patient-derived xenograft models (see figure). GPAT1 regulates the mitochondrial function by producing LPA which is an essential metabolite for maintaining mitochondrial fusion. Actually, the amount of LPA was decreased in GPAT1 knockdown acute leukemia cells. We next examined mitochondrial energy production by extracellular flux assay, and found that GPAT1 knockdown as well as FSG67 significantly suppressed oxygen consumption rate of acute leukemia cells. Consistent with the impaired mitochondrial function, FSG67 suppressed the mitochondrial membrane potential, indicating that GPAT1 should play a pivotal role in maintaining leukemia-specific mitochondrial function. These results collectively suggest that the synthesis of LPA from G3P catalyzed by GPAT1 has a critical role in propagation of acute leukemia cells irrespective of their lineage origin. Thus, GPAT1 is a novel and common therapeutic target for human acute leukemia through suppressing leukemia-specific mitochondrial function. Figure Disclosures Akashi: Celgene, Kyowa Kirin, Astellas, Shionogi, Asahi Kasei, Chugai, Bristol-Myers Squibb: Research Funding; Sumitomo Dainippon, Kyowa Kirin: Consultancy.

Modulation of lysophosphatidic acid (LPA) receptor activity: the key to successful neural regeneration?

Modulation of lysophosphatidic acid (LPA) receptor activity: the key to successful neural regeneration?

Functional Characterization of Physcomitrella patens Glycerol-3-Phosphate Acyltransferase 9 and an Increase in Seed Oil Content in Arabidopsis by Its Ectopic Expression.

Since vegetable oils (usually triacylglycerol [TAG]) are extensively used as food and raw materials, an increase in storage oil content and production of valuable polyunsaturated fatty acids (PUFAs) in transgenic plants is desirable. In this study, a gene encoding glycerol-3-phosphate acyltransferase 9 (GPAT9), which catalyzes the synthesis of lysophosphatidic acid (LPA) from a glycerol-3-phosphate and acyl-CoA, was isolated from Physcomitrella patens, which produces high levels of very-long-chain PUFAs in protonema and gametophores. P. patens GPAT9 shares approximately 50%, 60%, and 70% amino acid similarity with GPAT9 from Chlamydomonas reinhardtii, Klebsormidium nitens, and Arabidopsis thaliana, respectively. PpGPAT9 transcripts were detected in both the protonema and gametophores. Fluorescent signals from the eYFP:PpGPAT9 construct were observed in the ER of Nicotiana benthamiana leaf epidermal cells. Ectopic expression of PpGPAT9 increased the seed oil content by approximately 10% in Arabidopsis. The levels of PUFAs (18:2, 18:3, and 20:2) and saturated FAs (16:0, 18:0, and 20:0) increased by 60% and 43%, respectively, in the storage oil of the transgenic seeds when compared with the wild type. The transgenic embryos with increased oil content contained larger embryonic cells than the wild type. Thus, PpGPAT9 may be a novel genetic resource to enhance storage oil yields from oilseed crops.

Atorvastatin attenuates lysophosphatidic acid‐induced tau hyperphosphorylation through p38 MAPK kinase pathway in an Alzheimer's disease model

The prevalence of Alzheimer's disease (AD) is currently estimated to be around 6 million cases and is predicted to rapidly increase in the coming decades. The currently approved treatments fail to alter the underlying pathophysiology, provide only modest and temporary symptomatic relief and are associated with several side effects. Recent evidence suggests that vascular factors, in particular, lysophosphatidic acid (LPA), the most bioactive component of oxidized low‐density lipoprotein (oxLDL), play a crucial role in the pathophysiology of AD. Increased levels of LPA lead to activation of several intracellular signaling cascades thereby leading to neuroinflammation and neurodegeneration. Statins are cholesterol lowering agents of proven benefit in vascular disease and are also associated with reduction in circulating oxLDL levels. Additionally, several clinical studies suggest the risk of AD was substantially reduced with statins. Hence, the goal of the proposed research is to evaluate the role of the LPA signaling in AD pathogenesis and the effect of statin (atorvastatin) in attenuating LPA induced cognitive dysfunction. In vitro studies utilizing ShSy5y neuronal cell line showed atorvastatin attenuated LPA induced Amyloid beta and tau hyperphosphorylation. The effect of LPA on p38 MAPK Kinase and it's downstream signaling markers of apoptosis (BAX, BCL2) and inflammation (NF‐Kβ, IL‐6, TNFα) was analyzed through biochemical assays. We will utilize a high fat diet mouse model, to investigate the neuroprotective effects of atorvastatin. Novel object location test, Y‐maze and contextual fear conditioning will be performed to evaluate cognitive and behavioral deficits. To assess the effects of LPA and atorvastatin on hippocampal synaptic plasticity, we will measure long term potentiation and long‐term depression, which are the cellular correlates of learning and memory. Golgi cox staining to study the effect of LPA and atorvastatin on dendritic spine morphology is being performed. Western blot will also be used to measure levels of AMPA and NMDA receptor subunits. Biochemical assays will be performed to quantify levels of PSD‐95, synaptophysin, and ARC protein, which are proteins essential for synaptic maturity and plasticity. Finally, the neuroprotective effect of atorvastatin on LPA induced cognitive dysfunction will be analyzed by measuring the levels of autotaxin (ATX), an enzyme important for LPA synthesis. 4, 8‐ and 12‐months aged age. We believe our study will demonstrate that that atorvastatin through its pleotropic effects, attenuate LPA induced cognitive dysfunction by improving behavioral and cognitive deficits, synaptic dysfunction, and reducing the pathologies of AD thereby uncovering a molecular mechanism of LPA induced dyshomeostasis in AD.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Autotaxin‐LPA‐LPP3 axis regulates mitochondrial respiration prompting myocardial dysfunction

Background and ObjectiveAcute myocardial infarction (AMI) and ischemic heart disease are the two most prevalent causes of morbidity and mortality in the western world. Lysophosphatidic acid (LPA) a pro‐inflammatory, pro‐thrombotic bioactive glycerophospholipid plays a well‐known role in atherosclerotic disease; its role in myocardial dysfunction remains virtually unexplored. Following AMI, serum LPA concentration increases six‐fold over control subjects. Since LPA has a rapid turnover in the circulation, LPA production involves hydrolysis of lysophosphatidylcholine by the secreted enzyme autotaxin.In contrast, LPP3 catalyzes LPA dephosphorylation to generate lipid products that are not receptor active. The steady state of local and circulating LPA is balanced between these opposing pathways of LPA synthesis and degradation. The goal of this study was to determine the role of the autotaxin‐LPA‐LPP3 axis in myocardial dysfunction along with cardiomyocyte responses.MethodsTo study the role of the autotaxin‐LPA‐LPP3 axis in the myocardium, we used human induced pluripotent stem cell (IPS) cardiomyocytes and generated a cardiac‐specific Plpp3 deficient mouse strain. Mitochondrial bioenergetics was measured using the Seahorse XF24 analyzer.ResultsOur results show that exposure to LPA significantly decreased oxygen consumption rate (OCR; P&lt;0.001) and increased extracellular acidification rate (ECAR; P&lt;0.001) in IPS cardiomyocytes. Similar results were seen after subjecting the IPS cardiomyocytes to hypoxia where in the addition of autotaxin inhibitors had the reverse effect on OCR (P&lt;0.001) and ECAR (P&lt;0.001). LPA receptors blockade with pan‐Brp‐LPA restored the mitochondrial OCR (P&lt;0.001) and decreased the ECAR (P&lt;0.001). Generation of Plpp3 knockout mice (Plpp3Δ) showed increased mortality ~8 months. Plpp3Δ myocardium showed a distorted intercalated disc with damaged mitochondria with disorganized cristae and amorphous matrix densities as compared to lpp3fl in transmission electron microscopy. Lack of LPP3 resulted in deteriorating cardiac function. Plpp3Δ cardiomyocyte exposure to LPA significantly decreased oxygen consumption rate (OCR; P&lt;0.001) and increased extracellular acidification rate (ECAR; P&lt;0.001). Together these findings show that the absence of LPP3 increases LPA signaling and results in impaired mitochondrial function.Discussion and ConclusionsThe results presented in this study indicate that the autotaxin‐LPA‐LPP3 axis plays a critical role in the mitochondrial respiration and loss of LPP3 in cardiomyocytes from Plpp3Δ mice further confirms the impairment of myocardial function. Importantly, we demonstrate that autotaxin‐LPA‐LPP3 axis regulates mitochondrial respiration to limit myocardial function.Support or Funding InformationNational Institutes of Health Grants 1P20GM121307‐01A1 (Dr. Kevil) Sub‐Project ID: 8571 to Dr. Panchatcharam.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

LPAR2 and LPAR4 are the Main Receptors Responsible for LPA Actions in Ovarian Endometriotic Cysts.

Endometriosis has been considered as an estrogen (E2)-dependent and progesterone (P4)-resistant disease. On the other hand, lysophosphatidic acid (LPA) has been suggested as a significant modulator of ovarian pathology, acting via both LPA levels and LPA receptor (LPAR) upregulation. Therefore, the objective of the present study was to evaluate LPA concentration as well as LPARs, autotaxin (ATX), and phospholipase A2 (PLA2) expression in ovarian endometriotic cysts and normal endometrium with correlation of the expression of E2 and P4 receptors in endometriotic cysts. The analyses were carried out using the tissues derived from 37 patients with ovarian endometriosis and 20 endometrial samples collected from women without endometriosis were used as a control. We found that ovarian endometriotic cysts are a site of LPA synthesis due to the presence of enzymes involved in LPA synthesis in the tissue. Additionally, when we compared endometriotic cysts versus normal endometrium, we were able to show overexpression of 3 from 6 examined LPARs and both enzymes responsible for LPA synthesis in endometriotic cysts. Finally, we found the correlations between LPARs, ATX, and PLA2 and the expression of E2 and P4 receptors in endometriotic cysts. Owing to the high LPAR2 and LPAR4 transcript and protein expression in endometriotic ovarian cysts and positive correlations of both these receptors with the PR-B and ERβ, respectively, those receptors seem to be the most promising predictors of the endometriotic cysts as well as the main receptors responsible for LPA action in the ovarian endometriosis.