Neuropathy Target Esterase Research Articles

Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders.

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism and hair anomalies. PNPLA6 encodes neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a systematic evidence-based review of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6-associated clinical diagnoses unambiguously reclassified 36 variants as pathogenic and 10 variants as likely pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship, and the generation of a preclinical animal model, pave the way for therapeutic trials, using NTE as a biomarker.

Unraveling the link between neuropathy target esterase NTE/SWS, lysosomal storage diseases, inflammation, abnormal fatty acid metabolism, and leaky brain barrier.

Mutations in Drosophila Swiss cheese (SWS) gene or its vertebrate orthologue neuropathy target esterase (NTE) lead to progressive neuronal degeneration in flies and humans. Despite its enzymatic function as a phospholipase is well established, the molecular mechanism responsible for maintaining nervous system integrity remains unclear. In this study, we found that NTE/SWS is present in surface glia that forms the blood-brain barrier (BBB) and that NTE/SWS is important to maintain its structure and permeability. Importantly, BBB glia-specific expression of Drosophila NTE/SWS or human NTE in the sws mutant background fully rescues surface glial organization and partially restores BBB integrity, suggesting a conserved function of NTE/SWS. Interestingly, sws mutant glia showed abnormal organization of plasma membrane domains and tight junction rafts accompanied by the accumulation of lipid droplets, lysosomes, and multilamellar bodies. Since the observed cellular phenotypes closely resemble the characteristics described in a group of metabolic disorders known as lysosomal storage diseases (LSDs), our data established a novel connection between NTE/SWS and these conditions. We found that mutants with defective BBB exhibit elevated levels of fatty acids, which are precursors of eicosanoids and are involved in the inflammatory response. Also, as a consequence of a permeable BBB, several innate immunity factors are upregulated in an age-dependent manner, while BBB glia-specific expression of NTE/SWS normalizes inflammatory response. Treatment with anti-inflammatory agents prevents the abnormal architecture of the BBB, suggesting that inflammation contributes to the maintenance of a healthy brain barrier. Considering the link between a malfunctioning BBB and various neurodegenerative diseases, gaining a deeper understanding of the molecular mechanisms causing inflammation due to a defective BBB could help to promote the use of anti-inflammatory therapies for age-related neurodegeneration.

Human blood markers of cholinergic neurotoxicity and neuropathy: A useful guide for laboratory applications

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are useful markers to assess the effects of exposure to anticholinesterase insecticides (Anti-AChE). In addition, lymphocyte neuropathy target esterase (LNTE) has been used as biomarker of neuropathic organophosphate compounds (OPs). Thus, this study evaluates the main types of circulating biomarkers related to the cholinergic system and to the neuropathy induced by OPs in standardized human samples. To achieve this objective, total protein of human plasma, erythrocytes and lymphocytes were first standardized, and then AChE, BChE and LNTE activities in human blood were evaluated in the presence of inhibitors. The acceptance criteria of the regulatory agency were respected with coefficients of regression of curves of 0.9972 for cholinesterase and 0.9956 for LNTE analyses. The wavelength established to perform cholinesterase assay was 450 nm and the time of incubation of the enzymes with inhibitors was 30 min. Differences were observed among the IC50 values regarding the in vitro inhibition of AChE, BChE and LNTE in the presence of OPs. In conclusion, the procedures demonstrated by the present work were simple, fast, inexpensive, sensitive, easy to be replicated and suitable to make conclusions about the neurotoxicity induced by Anti-AChE and neuropathic OPs.

Computational Modeling Study of the Binding of Aging and Non-Aging Inhibitors with Neuropathy Target Esterase

Computational Modeling Study of the Binding of Aging and Non-Aging Inhibitors with Neuropathy Target Esterase

The alteration of the expression level of neuropathy target esterase in human neuroblastoma SK-N-SH cells disrupts cellular phospholipids homeostasis

Neuropathy target esterase (NTE) has been proven to act as a lysophospholipase (LysoPLA) and phospholipase B (PLB) in mammalian cells. In this study, we took human neuroblastoma SK-N-SH cells as the research object and explored the effect of NTE on phospholipid homeostasis. The results showed that phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) levels significantly increased (> 40%), while glycerophosphocholine (GPC) decreased (below 60%) after NTE gene was knockdown in the cells (NTE < 30% of control), which were prepared by gene silencing with dsRNA-NTE. However, in the NTE-overexpressed cells (NTE > 50% of control), which were prepared by expressing recombinant catalytic domain of NTE, LPC remarkably decreased (below 80%) and GPC enhanced (> 40%). Mipafox, a neuropathic organophosphorus compound (OP), significantly inhibited NTE-LysoPLA and NTE-PLB activities (> 95–99% inhibition at 50 μM), which was accompanied with a decreased GPC level (below 40%) although no change of the PC and LPC levels was observed; while paraoxon, a non-neuropathic OP, suppresses neither the activities of NTE-phospholipases nor the levels of PC, LPC, and GPC. Thus, we concluded that both the stable up- or down-regulated expression of NTE gene and the loss of NTE-LysoPLA/PLB activities disrupts phospholipid homeostasis in the cells although the inhibition of NTE activity only decreased GPC content without altering PC and LPC levels.

An Investigation of the Neurotoxic Effects of Malathion, Chlorpyrifos, and Paraquat to Different Brain Regions

Acute or chronic exposures to pesticides have been linked to neurotoxicity and the potential development of neurodegenerative diseases (NDDs). This study aimed to consider the neurotoxicity of three widely utilized pesticides: malathion, chlorpyrifos, and paraquat within the hippocampus (HC), corpus striatum (CS), cerebellum (CER), and cerebral cortex (CC). Neurotoxicity was evaluated at relatively low, medium, and high pesticide dosages. All pesticides inhibited acetylcholinesterase (AChE) and neuropathy target esterase (NTE) in each of the brain regions, but esterase inhibition was greatest in the HC and CS. Each of the pesticides also induced greater disruption to cellular bioenergetics within the HC and CS, and this was monitored via inhibition of mitochondrial complex enzymes I and II, reduced ATP levels, and increased lactate production. Similarly, the HC and CS were more vulnerable to redox stress, with greater inhibition of the antioxidant enzymes catalase and superoxide dismutase and increased lipid peroxidation. All pesticides induced the production of nuclear Nrf2 in a dose-dependent manner. Collectively, these results show that pesticides disrupt cellular bioenergetics and that the HC and CS are more susceptible to pesticide effects than the CER and CC.

The Catalytic Domain of Neuropathy Target Esterase Influences Lipid Droplet Biogenesis and Lipid Metabolism in Human Neuroblastoma Cells.

As an endoplasmic reticulum (ER)-anchored phospholipase, neuropathy target esterase (NTE) catalyzes the deacylation of lysophosphatidylcholine (LPC) and phosphatidylcholine (PC). The catalytic domain of NTE (NEST) exhibits comparable activity to NTE and binds to lipid droplets (LD). In the current study, the nucleotide monophosphate (cNMP)-binding domains (CBDs) were firstly demonstrated not to be essential for the ER-targeting of NTE, but to be involved in the normal ER distribution and localization to LD. NEST was associated with LD surface and influenced LD formation in human neuroblastoma cells. Overexpression of NEST enhances triacylglycerol (TG) accumulation upon oleic acid loading. Quantitative targeted lipidomic analysis shows that overexpression of NEST does not alter diacylglycerol levels but reduces free fatty acids content. NEST not only lowered levels of LPC and acyl-LPC, but not PC or alkyl-PC, but also widely altered levels of other lipid metabolites. Qualitative PCR indicates that the increase in levels of TG is due to the expression of diacylglycerol acyltransferase 1 gene by NEST overexpression. Thus, NTE may broadly regulate lipid metabolism to play roles in LD biogenesis in cells.

PNPLA6/NTE, an Evolutionary Conserved Phospholipase Linked to a Group of Complex Human Diseases.

Patatin-like phospholipase domain-containing protein 6 (PNPLA6), originally called Neuropathy Target Esterase (NTE), belongs to a family of hydrolases with at least eight members in mammals. PNPLA6/NTE was first identified as a key factor in Organophosphate-induced delayed neuropathy, a degenerative syndrome that occurs after exposure to organophosphates found in pesticides and nerve agents. More recently, mutations in PNPLA6/NTE have been linked with a number of inherited diseases with diverse clinical symptoms that include spastic paraplegia, ataxia, and chorioretinal dystrophy. A conditional knockout of PNPLA6/NTE in the mouse brain results in age-related neurodegeneration, whereas a complete knockout causes lethality during embryogenesis due to defects in the development of the placenta. PNPLA6/NTE is an evolutionarily conserved protein that in Drosophila is called Swiss-Cheese (SWS). Loss of SWS in the fly also leads to locomotory defects and neuronal degeneration that progressively worsen with age. This review will describe the identification of PNPLA6/NTE, its expression pattern, and normal role in lipid homeostasis, as well as the consequences of altered NPLA6/NTE function in both model systems and patients.

Interactions of human acetylcholinesterase with phenyl valerate and acetylthiocholine: Thiocholine as an enhancer of phenyl valerate esterase activity

Phenyl valerate (PV) is a neutral substrate for measuring the PVase activity of neuropathy target esterase (NTE), a key molecular event of organophosphorus-induced delayed neuropathy. This substrate has been used to discriminate and identify other proteins with esterase activity and potential targets of organophosphorus (OP) binding. A protein with PVase activity in chicken (model for delayed neurotoxicity) was identified as butyrylcholinesterase (BChE). Further studies in human BChE suggest that other sites might be involved in PVase activity. From the theoretical docking analysis, other more favorable sites for binding PV related to the Asn289 residue located far from the catalytic site (“PVsite”) were deduced.In this paper, we demonstrate that acetylcholinesterase is also able to hydrolyze PV. Robust kinetic studies of interactions between substrates PV and acetylthiocholine (AtCh) were performed. The kinetics did not fit the classic competition models among substrates. While PV interacts as a competitive inhibitor in AChE activity, AtCh at low concentrations enhances PVase activity and inhibits this activity at high concentrations. Kinetic behavior suggests that the potentiation effect is caused by thiocholine released at the active site, where AtCh could act as a Trojan Horse. We conclude that the products released at the active site could play an important role in the hydrolysis reactions of different substrates in biological systems.

Strategy for searching potential partner genes of Drosophila melanogaster Sws gene

Aim. The Drosophila swiss cheese (sws) gene is a mammalian ortholog of neuropathy target esterase (NTE or PNPLA6). This protein is involved in the functioning of the nervous system and causes some kinds of polyneuropathy with the mechanism unknown. Genes-interactors of the sws gene should be found to investigate the cellular mechanism of SWS/NTE-dependent neuropathy formation and to find out what signaling pathways SWS is involved in. Methods. The search was done in the Drosophila database – Flybase, in the NCBI (Gene) database to search for orthologs, and the String web resource was used in the case of potential protein interactions. Results. Only four experimentally identified genes-interactors were listed in the Flybase. Based on the expression changes data of 28 genes at PNPLA6 silencing, a theoretical search for the corresponding orthologs in Drosophila was done. The in silico assay predicted 10 proteins that are probably functioning within one metabolic pathway. Conclusions. The methods applied gave us a wide list of genes that can interact with sws at different levels: from the expression pattern to the phenotype. Therefore, 25 potentially partner genes were selected to verify the genetic interaction of these genes in vivo.&#x0D; Keywords: gene swiss cheese, neuropathy target esterase, neurodegeneration, in silico analysis, genes interaction, Drosophila melanogaster.

SARM1-mediated wallerian degeneration: A possible mechanism underlying organophosphorus-induced delayed neuropathy

Some organophosphorus compounds (OPs) can cause a type of delayed neurotoxicity in human being, which is known as organophosphorus-induced delayed neuropathy (OPIDN). Signs and symptoms of the patients include tingling and sensory loss of the hands and feet, followed by progressive muscle weakness in the lower and upper limbs, and ataxia. Pathologically, OPIDN are characterized by distal sensorimotor axonopathy due to the distal axonal degeneration of nerve tracts located in central and peripheral nervous systems. The morphological pattern of the distal axonopathy is similar to Wallerian degeneration that occurs after nerve injury in vitro. It is generally acknowledged that inhibition and subsequent aging of neuropathy target esterase (NTE) is required for the occurrence of OPIDN. However, the underlying mechanisms through which NTE triggers axonal degeneration in OPIDN is still largely unclear. Recently, sterile alpha and toll/interleukin receptor motif-containing protein 1（SARM1) has been identified as a key player in Wallerian degeneration. In physical and chemical transection of axons, SARM1 was found to promotes axon degeneration by hydrolyzing NAD+. By contrast, SARM1 deficiency could prevent neuron degeneration in response to a wide range of insults. Furthermore, SARM1 can also translocate to mitochondria and cause mitochondrial damage, thus triggering axon degeneration and neuron death. These findings suggested the existence of a pathway in axonal degeneration that might be targeted therapeutically. Here, we hypothesize that SARM1 activation after NTE inhibition and aging might be an etiological factor in OPIDN that regulates Wallerian-like degeneration. Analysing SARM1 mediated NAD degeneration pathway and its upstream activators in OPIDN could contribute to the development of novel therapies to treat OPIDN.

Decrease of an intracellular organic osmolyte contributes to the cytotoxicity of organophosphate in neuroblastoma cells in vitro

Organophosphorus compounds (OP) causes prominent delayed neuropathy in vivo and cytotoxicity to neuronal cells in vitro. The primary target protein of OP’s neurotoxicity is neuropathy target esterase (NTE), which can convert phosphatidylcholine (PC) to glycerophosphocholine (GPC). Recent studies reveal that autophagic cell death is important for the initiation and progression of OP-induced neurotoxicity both in vivo and in vitro. However, the mechanism of how OP induces autophagic cell death is unknown. Here it is found that GPC is an important organic osmolyte in the neuroblastoma cells, and treatment with tri-o-cresyl phosphate (TOCP), a representative OP, leads to the decrease of GPC and imbalance of extracellular and intracellular osmolality. Knockdown of GPC metabolizing enzyme glycerophosphodiester phosphodiesterase domain containing 5 (GDPD5) reverses TOCP-induced autophagic cell death, which further supports the notion that the reduced GPC level leads to the autophagic cell death. Furthermore, it is found that autophagic cell death is due to the induction of reactive oxygen species (ROS) and mitochondrial damage by imbalance of osmolality with TOCP treatment. In summary, this study reveals that TOCP treatment decreases GPC level and intracellular osmolality, which induces ROS and mitochondrial damage and leads to the cell death and neurite degradation by autophagy. This study lays the foundation for further investigations on the potential therapeutic approaches for OP neurotoxicity or NTE mutation-related neurological diseases.

Hydrolysis of chiral organophosphorus compounds by phosphotriesterases and mammalian paraoxonase-1.

Some organophosphorus compounds (OPs), which are used in the manufacturing of insecticides and nerve agents, are racemic mixtures with at least one chiral center with a phosphorus atom. Acute exposure of humans to these mixtures induces the covalent modification of acetylcholinesterase (AChE) and neuropathy target esterase (NTE) and causes a cholinergic syndrome or organophosphate-induced delayed polyneuropathy syndrome (OPIDP). These irreversible neurological effects are due to the stereoselective interaction of the racemic OPs with these B-esterases (AChE and NTE) and such interactions have been studied in vivo, ex vivo and in vitro, using stereoselective hydrolysis by A-esterases or phosphotriesterases (PTEs) and the PTE from Pseudomonas diminuta, and paraoxonase-1 (PON1) from mammalian serum. PON1 has a limited hydrolytic potential of the racemic OPs, while the bacterial PTE exhibits a significant catalytic activity on the less toxic isomers P(+) of the nerve agents. Avian serum albumin also shows a hydrolyzing capacity of chiral OPs with oxo and thio forms. There are ongoing environmental and bioremediation efforts to design and produce recombinants as bio-scavengers of OPs.

Repeated low-dose exposures to sarin disrupted the homeostasis of phospholipid and sphingolipid metabolism in guinea pig hippocampus

Repeated low-level exposure to sarin results to hippocampus dysfunction. Metabonomics involves a holistic analysis of a set of metabolites in an organism in the search for a relationship between these metabolites and physiological or pathological changes. The objective of the present study was to evaluate the effects of repeated exposure to low-level sarin on the metabonomics in hippocampus of a guinea pig model. Guinea pigs were divided randomly into control and sarin treated groups (n = 14). Guinea pigs in the control group received saline; while the sarin-treated group received 0.4×LD50 (16.8 μg/kg) sarin. Daily injections (a total of 14 days) were administered sc between the shoulder blades in a volume of 1.0 ml/kg body weight. At the end of the final injection, 6 animals in each group were chosen for Morris water maze test. The rest guinea pigs (n = 8 for each group) were sacrificed by decapitation, and hippocampus were dissected for analysis. Compared with the control-group, the escape latency in sarin-group was significantly (p < 0.05) longer while the crossing times were significantly decreased in the Morris water task (p < 0.05). Sarin inhibited activities of acetylcholinesterase (AChE) and neuropathy target esterase (NTE) in hippocampus. The AChE activity of hippocampus from sarin-treated groups is equivalent to 59.9 ± 6.4 %, and the NTE activity of hippocampus from sarin-groups is equivalent to 78.1 ± 8.3 % of that from control-group. Metabolites were identified and validated. A total of 14 variables were selected as potential biomarkers. Phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidic acid (PA), phosphatidylglycerol (PG), phosphatidylinositol (PI), Lysophosphatidylethanolamine (LysoPE or LPE)] and sphingolipids (SPs) [sphinganine (SA), phytosphingosine (PSO) and sphinganine-1-phosphate (SA1P)] were clearly modified. In conclusion, repeated low-dose exposures to sarin disrupted the homeostasis of phospholipid and sphingolipid metabolism in guinea pig hippocampus and may lead to a neuronal-specific function disorders. Identified metabolites such as SA1P need to be studied more deeply on their biological function that against sarin lesions. In future research, we should pay more attention to characterize the physiological roles of lipid metabolism enzymes as well as their involvement in pathologies induced by repeated low-level sarin exposure.

Reduced neuropathy target esterase in pre-eclampsia suppresses tube formation of HUVECs via dysregulation of phospholipid metabolism.

Recently, studies have shown that neuropathy target esterase (NTE) is essential to placental and normal blood vessel development. However, whether it is involved in abnormal placenta angiogenesis of pre-eclampsia remains unknown. Thus, our aim was to observe the expression of NTE in pre-eclamptic placentas and its effects and mechanism of NTE on the migration and the tube formation of human umbilical vein endothelial cells (HUVECs). Immunohistochemical staining showed that the NTE protein was intensely located in blood vessels of the normal pregnant placenta. However, western blot revealed that the expression level of NTE protein was significantly reduced in pre-eclamptic placenta. The results indicated that overexpression of NTE significantly promoted the migration and the tube formation of HUVECs compared with those of the control and scramble short hairpin RNA (shRNA) group. Conversely, NTE shRNA obviously inhibited the migration and the tube formation of HUVECs. Additionally, chromatography assay evidenced that NTE overexpression significantly reduced the level of phosphatidylcholine (PC) of HUVECs, but NTE shRNA obviously increased the level of PC of HUVECs. Furthermore, exogenous PC and lysophosphatidylcholine (LPC) significantly inhibited the tube formation of HUVECs in a dose-dependent manner. Collectively, our results suggest that reduced NTE in placenta may contribute to abnormal placenta angiogenesis of pre-eclampsia via the dysregulation of PC and LPC metabolism.

SWS/NTE-dependent neuropathy is the model system to study neurodegeneration

Today there is many described neurodegenerative D. melanogaster mutants, which characterized by development of degenerative changes in brain. One of them are a swiss cheese (sws) gene mutants. Mutations in this gene causes apoptosis of neurons and hyperwrapping of their somas by the glial cells, reducing of life expectancy and decrease of locomotion. The sws gene is the ortholog of mammal’s neuropathy target esterase (NTE / PNPLA6). NTE is s neuronal, transmembrane protein, that possesses serinesterase activity, and can be the target for neurotoxic organophosphorus compounds activity. Mutations in PNPLA6 gene cause number hereditary neurodegenerative disorders, which nowadays are incurable. The search for therapeutic agents require use of model objects because researches on humans have both methodical and ethical limitations. During two last decades D. melanogaster has proven itself as a good model for study of neurodegenerative diseases. In this review, we described general characteristics of D. melanogaster gene sws, consequences of its mutations and provided evidences of high conservatism of gene product.&#x0D; Keywords: gene swiss cheese, neuropathy target esterase, neurodegeneration, brain, life span.

Changes of Neuropathy Target Esterase Affect Phospholipid Homeostasis in SK-N-SH Cells

Neuropathy target esterase (NTE), is a membrane protein located in the endoplasmic reticulum (ER). NTE has the activity of phospholipase B and can catalyze the deacylation of phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) to glycerylcholine (GPC). It is phosphorylated and aged by organophosphorus compounds (OPs), that induce delayed neuropathy in humans and sensitive animals. Our previous study has reported that the disruption of ER phospholipid homeostasis caused by the NTE inhibition may contribute to the initiation of the organophosphate-induced delayed neurotoxicity (OPIDN), while it is unknown how the disturbed phospholipid homeostasis initiates OPIDN. It is difficult to change phospholipids in in vivo experiments. Therefore, an in vitro model is urgently needed to explain the role of phospholipid homeostasis disorders in OPIDN. In this study, we altered the expression of NTE in SK-N-SH cells and determined its phospholipid component by using HPLC-MS. Our results showed that the changes of NTE affected the levels of PC, sphingomyelin (SM), phosphatidylethanolamine (PE), phosphatidylserine (PS), lysophosphatidylserine (LPS), phosphatidyl-glycerol (PG), and phosphatidylinositol (PI). Our results were consistent with the in vivo results. Furthermore, our findings indicate that the SK-N-SH cell model is a significantly useful method for the further research on how the changes of phospholipid homeostasis initiate the OPIDN, which is easier than the in vivo experiments in practice.

Bi-allelic variants in PNPLA6 possibly associated with Parkinsonian features in addition to spastic paraplegia phenotype.

Variants in the PNPLA6 gene are known to cause 4 distinct phenotypes. One known phenotype is Hereditary Spastic Paraplegia type 39 (HSP 39), a rare neurodegenerative condition characterized by variable onset of lower limb spasticity, weakness and ataxia. Little is known about complications of HSP 39 in adulthood. Here, we report a family of three siblings who presented with bilateral lower limb spasticity in childhood, consistent with HSP, with confirmed bi-allellic PNPLA6 mutations. Two siblings developed parkinsonian features in middle age, a novel finding in this sibship. The proband had a positive dopamine transporter scan, indicating degeneration in dopaminergic neurons, and dopa-responsive extrapyramidal symptoms. Testing for known genetic causes of Parkinsonism was negative. The PNPLA6 gene encodes neuropathy target esterase, an enzyme involved in lipid metabolism that is critical to the stability of cell membranes. We hypothesize that the development of Parkinsonism in these patients may be related to the PNPLA6 mutations, as lipid dysregulation has been implicated in the pathogenesis of Parkinson disease.

An unbiased lipidomics approach identifies key lipid molecules as potential therapeutic targets of Dohongsamul-tang against non-alcoholic fatty liver diseases in a mouse model of obesity

Ethnopharmacological relevanceDohongsamul-tang (DST) is a traditional herbal formula used to promote the blood circulation and inhibit inflammation, and also widely has been used in the treatment of patients with chronic liver diseases in Korea and China. Aim of the studyThis study aimed to investigate the effect of DST on regulation of lipid metabolism of chronic liver diseases in mouse model of non-alcoholic fatty liver diseases (NAFLD). Materials and methodsIn this study, we evaluated the effect of DST on high-fat and high-cholesterol diet (HFHC, 40% fat and 1% cholesterol)-induced NAFLD, and applied unbiased lipidomics using ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF MS) coupled with multivariate analysis. ResultsDST improved hepatic morphology and reduced levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). In addition, DST inhibited hepatic lipid accumulation through the downregulation of C/EBPα, PPARγ, and pAMPK. To further elucidate the effect of DST on hepatic lipid metabolism, we applied UPLC/Q-TOF MS-based lipidomics. The score plots of partial least squares-discriminant analysis (PLS-DA) showed that DST changed the lipid metabolic pattern of high-fat and high-cholesterol diet (HFHC) mice. Twenty-two lipid metabolites were selected as biomarkers regulated by DST and pathway analysis revealed that sphingolipid metabolism and glycerophospholipid metabolism were associated with the effect of DST on NAFLD. Among the 22 selected biomarkers, 14 were phospholipids, and DST significantly reversed the increased expression of lysophospholipase 3 (LYPLA3) and neuropathy target esterase (NTE), which are key enzymes in glycerophospholipid metabolism. Given that alterations in sphingolipids and phospholipids can have effects on apoptosis and insulin resistance (IR), we subsequently investigated changes in the expression of apoptosis-related proteins, including Bcl-2-associated X protein (Bax) and B-cell lymphoma 2 (Bcl2), and IR-related markers after DST treatment. We accordingly found that the ratio of Bax to Bcl-2 expression, a maker of apoptosis, was also elevated in HFHC mice and reduced by DST treatment. In addition, DST enhanced hepatic insulin signaling by upregulating the expression of insulin receptor substrate 1 (IRS-1) and phospho-protein kinase B (pAKT), and oral glucose tolerance test (OGTT) analysis indicated that this herbal preparation also ameliorated systemic IR. ConclusionsThis study suggested that DST might have an effect on NAFLD by regulating the metabolism of lipids such as phospholipids and sphingolipids and demonstrated that lipidomic profiling is useful to investigate the therapeutic effects of herbal decoctions from traditional Korean and Chinese medicine.

Neuropathy target esterase (NTE/PNPLA6) and organophosphorus compound-induced delayed neurotoxicity (OPIDN).

Systemic inhibition of neuropathy target esterase (NTE) with certain organophosphorus (OP) compounds produces OP compound-induced delayed neurotoxicity (OPIDN), a distal degeneration of axons in the central nervous system (CNS) and peripheral nervous system (PNS), thereby providing a powerful model for studying a spectrum of neurodegenerative diseases. Axonopathies are important medical entities in their own right, but in addition, illnesses once considered primary neuronopathies are now thought to begin with axonal degeneration. These disorders include Alzheimer's disease, Parkinson's disease, and motor neuron diseases such as amyotrophic lateral sclerosis (ALS). Moreover, conditional knockout of NTE in the mouse CNS produces vacuolation and other degenerative changes in large neurons in the hippocampus, thalamus, and cerebellum, along with degeneration and swelling of axons in ascending and descending spinal cord tracts. In humans, NTE mutations cause a variety of neurodegenerative conditions resulting in a range of deficits including spastic paraplegia and blindness. Mutations in the Drosophila NTE orthologue SwissCheese (SWS) produce neurodegeneration characterized by vacuolization that can be partially rescued by expression of wild-type human NTE, suggesting a potential therapeutic approach for certain human neurological disorders. This chapter defines NTE and OPIDN, presents an overview of OP compounds, provides a rationale for NTE research, and traces the history of discovery of NTE and its relationship to OPIDN. It then briefly describes subsequent studies of NTE, including practical applications of the assay; aspects of its domain structure, subcellular localization, and tissue expression; abnormalities associated with NTE mutations, knockdown, and conventional or conditional knockout; and hypothetical models to help guide future research on elucidating the role of NTE in OPIDN.