Phospholipids Phosphatidylethanolamine Research Articles

Selenoprotein I is indispensable for ether lipid homeostasis and proper myelination

Selenoprotein I (SELENOI) catalyzes the final reaction of the CDP-ethanolamine branch of the Kennedy pathway, generating the phospholipids phosphatidylethanolamine (PE) and plasmenyl-PE. Plasmenyl-PE is a key component of myelin and is characterized by a vinyl ether bond that preferentially reacts with oxidants, thus serves as a sacrificial antioxidant. In humans, multiple loss-of-function mutations in genes affecting plasmenyl-PE metabolism have been implicated in hereditary spastic paraplegia (HSP), including SELENOI. Herein, we developed a mouse model of nervous system-restricted SELENOI deficiency that circumvents embryonic lethality caused by constitutive deletion and recapitulates phenotypic features of HSP. Resulting mice exhibited pronounced alterations in brain lipid composition, which coincided with motor deficits and neuropathology including hypomyelination, elevated reactive gliosis, and microcephaly. Further studies revealed increased lipid peroxidation in oligodendrocyte lineage cells and disrupted oligodendrocyte maturation both in vivo and in vitro. Altogether, these findings detail a critical role for SELENOI-derived plasmenyl-PE in myelination that is of paramount importance for neurodevelopment.

The phospholipids cardiolipin and phosphatidylethanolamine differentially regulate MDC biogenesis.

Cells utilize multiple mechanisms to maintain mitochondrial homeostasis. We recently characterized a pathway that remodels mitochondria in response to metabolic alterations and protein overload stress. This remodeling occurs via the formation of large membranous structures from the mitochondrial outer membrane called mitochondrial-derived compartments (MDCs), which are eventually released from mitochondria and degraded. Here, we conducted a microscopy-based screen in budding yeast to identify factors that regulate MDC formation. We found that two phospholipids, cardiolipin (CL) and phosphatidylethanolamine (PE), differentially regulate MDC biogenesis. CL depletion impairs MDC biogenesis, whereas blocking mitochondrial PE production leads to constitutive MDC formation. Additionally, in response to metabolic MDC activators, cellular and mitochondrial PE declines, and overexpressing mitochondrial PE synthesis enzymes suppress MDC biogenesis. Altogether, our data indicate a requirement for CL in MDC biogenesis and suggest that PE depletion may stimulate MDC formation downstream of MDC-inducing metabolic stress.

Relationship between phospholipid molecules species and volatile compounds in grilled lambs during the heating process

The present study used a comprehensive analysis combining headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) to investigate changes in volatile compounds and phospholipid molecules in grilled lambs. The results revealed 19 key volatile compounds (OAV > 1) involved in the grilling process of lambs. Additionally, UPLC-ESI-MS/MS analysis detected 142 phospholipid molecules in grilled lamb, with phosphatidylcholine exhibiting the highest content (36.62 %), followed by phosphatidyl ethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidyl glycerol, and phosphatidic acid. Through partial least squares analysis, 63 key differential phospholipids were identified. Principal component analysis of the key differential phospholipids and volatile compounds indicated that phosphatidylcholine and phosphatidyl ethanolamine phospholipids are the key substrates in forming volatile compounds in grilled lambs. This information is essential for precisely regulating the flavor profile, enhancing the grilling process, and minimizing the production of harmful compounds in grilled meat products.

Lambda-cyhalothrin'nin Oreochromis niloticus’un Solungaç Fosfolipid (PL) Alt Sınıfı Üzerine Etkisi

Fatty acids have a crucial role in providing energy and performing essential functions in living organisms. Moreover, these substances exhibit the most significant alterations in their structure based on ecotoxicological parameters when viewed from a biochemical perspective. These bioactive chemicals are present in the cellular architecture. The study of these fatty acids, crucial for maintaining the integrity and permeability of cell membranes, holds great significance for all living organisms. Consequently, doing fatty acid analysis specifically at the phospholipid level holds significant importance.
 The impact of lambda cyhalothrin on the fatty acid content of several phospholipid subclasses (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylserine (PS) in the gill tissue of O. niloticus (Perciformes: Cichlidae) was assessed using gas chromatography. The alterations in the fatty acid composition was analyzed 21 days after exposure.
 Following the complete extraction of lipids from gill tissue, the tissue was subsequently separated into different subclasses of phospholipids using thin layer chromatography. The samples were subjected to methylation and then evaluated using Gas Chromatography to determine the percentage of the fatty acid. After doing the analysis, a grand total of 16 fatty acids were identified. The research revealed that the primary fatty acids were 16:0 and 18:0 of saturated fatty acids, monounsaturated 18:1n-9, and polyunsaturated 18:2n-6, 20:4n-6, and 22:6n-6. Upon analyzing the distribution of fatty acids, it was observed that PC, PE, and PI included 16:0, PE contained 18:1, PE and PS contained C18:2n-6 and 20:4n-6, and significant alterations in C22:6n-3 were detected in PE. Our investigation revealed that the n-3/n-6 ratio of fish in the PE subclass was the lowest when compared to PC, PI, and PS.

STAT5-Feedback Controls Distinct Metabolic States for Dynamic Transitions between Cellular Activation and Quiescence in Acute Lymphoblastic Leukemia

Background and significance: B-cell acute lymphoblastic leukemia (B-ALL) is characterized by dynamic shifts between activation and quiescence. These cycles are predicated by fluctuations in oncogenic signaling, which mimic pre-BCR and cytokine receptor signaling, e.g. IL7 receptor signaling and phosphorylation of STAT5. These fluctuations in cytokine receptor and STAT5 signaling are mitigated by powerful feedback regulators, including CISH and SOCS (suppressors of cytokine signaling) family members. While B-ALL cells depend on oncogenic STAT5 signaling, CISH and SOCS2 negative feedback regulators of STAT5 are highly expressed in aggressive B-ALL and high expression levels are strongly linked to poor clinical outcome, positive MRD and increased likelihood of bone marrow relapse in children (COG P9906) and adults (ECOG E2993). To determine whether high levels of CISH and SOCS2 are biomarkers of high oncogenic STAT5 signaling or mechanistically contribute to clonal fitness and adaptability of B-ALL, we performed genetic experiments in mouse models for B-ALL. Here we examined the mechanisms and consequences of active and inactive states of STAT5 by studying constitutively active (CA) and non-phosphorylatable Y694F (YF) mutations of STAT5. Results: Consistent with a central role of STAT5-feedback control in B-ALL survival, inducible ablation of Cishfl/fl resulted in rapid depletion of B-ALL cells. Socs2-/- B-ALL cells rapidly underwent cellular senescence, lacked colony forming and leukemia-initiating capacity in serial transplantation experiments. Likewise direct interference with STAT5-function, by mutations resulting in constitutive activation (STAT5-CA) or an inactive state (STAT5-YF). Consistent with a requirement of adaptive STAT5-feedback control in B-ALL, both Stat5-CA and Stat5-YF resulted in rapid cell death. Induction of Stat5-CA caused accumulation of biomass indicated by their increased cell size, whereas Stat5-YF caused rapid cell shrinkage ( Figure A). To determine whether the mTOR cell growth pathway was responsible for cell death induced by Stat5-CA, we tested whether the genetic deletion of Mtor or pharmacological inhibition of protein synthesis were sufficient to rescue B-ALL cell death. As expected, B-ALL cells retaining intact Mtor rapidly underwent energy crisis and cell death, while genetic deletion of Mtor reversed the toxic effects of Stat5-CA, suggesting that Stat5-CA is associated with excessive protein synthesis and defective ER turnover. Indeed, Stat5-CA increased protein synthesis rate and ER content compared to EV control, and these effects were opposed by Stat5-YF. To compare the metabolic outcomes of Stat5-CA and Stat5-YF, we performed mass spectrometry-based metabolomic analyses ( Figure B). Consistent with the role of mTOR in promoting glycolysis, Stat5-CA increased the content of glycolytic intermediates in B-ALL cells. In contrast, Stat5-YF increased phospholipid intermediates and phosphatidylethanolamine (PtdEtn). Opposed by Myc, Stat5-YF increased the expression levels of Bcl6 and autophagic genes, suggesting that Bcl6-dependent programs promote PtdEtn-LC3B conjugation, thereby autophagosome formation. As expected, microscopic validation with LC3B-GFP reporter revealed that Stat5-YF increased the number of LC3B-GFP puncta, upon pharmacological inhibition of autophagosome-lysosome fusion ( Figure A). Consistent with STAT5-CA promoting Myc- as opposed to STAT5-YF driving Bcl6-dependent programs, a flow cytometry analysis of Myc-eGFP/Bcl6-mCherry dual reporter expression in murine B-ALL cells demonstrated that changes between glycolytic Myc+ and autophagic Bcl6+ states were the direct consequence of Stat5-CA and Stat5-YF induction, respectively. Conclusions: Our results demonstrate feedback regulators of STAT5, including SOCS2 and CISH are not only biomarkers of increased oncogenic STAT5 activity and a more aggressive course of disease linked to poor overall outcomes. Importantly, negative STAT5 feedback control mechanisms are essential to enable nimble adaptations of B-ALL cells in response to fluctuations of oncogenic signaling strength and availability of nutrients during distinct metabolic states of cellular activation (MYC) and quiescence (BCL6).

Redox-mediated activation of ATG3 promotes ATG8 lipidation and autophagy progression in Chlamydomonas reinhardtii.

Autophagy is one of the main degradative pathways used by eukaryotic organisms to eliminate useless or damaged intracellular material to maintain cellular homeostasis under stress conditions. Mounting evidence indicates a strong interplay between the generation of reactive oxygen species and the activation of autophagy. Although a tight redox regulation of autophagy has been shown in several organisms, including microalgae, the molecular mechanisms underlying this control remain poorly understood. In this study, we have performed an in-depth in vitro and in vivo redox characterization of ATG3, an E2-activating enzyme involved in ATG8 lipidation and autophagosome formation, from 2 evolutionary distant unicellular model organisms: the green microalga Chlamydomonas (Chlamydomonas reinhardtii) and the budding yeast Saccharomyces cerevisiae. Our results indicated that ATG3 activity from both organisms is subjected to redox regulation since these proteins require reducing equivalents to transfer ATG8 to the phospholipid phosphatidylethanolamine. We established the catalytic Cys of ATG3 as a redox target in algal and yeast proteins and showed that the oxidoreductase thioredoxin efficiently reduces ATG3. Moreover, in vivo studies revealed that the redox state of ATG3 from Chlamydomonas undergoes profound changes under autophagy-activating stress conditions, such as the absence of photoprotective carotenoids, the inhibition of fatty acid synthesis, or high light irradiance. Thus, our results indicate that the redox-mediated activation of ATG3 regulates ATG8 lipidation under oxidative stress conditions in this model microalga.

Tumor Lipid Signatures Are Descriptive of Acquisition of Therapy Resistance in an Endocrine-Related Breast Cancer Mouse Model.

The lipid metabolism adaptations of estrogen and progesterone receptor-positive breast cancer tumors from a mouse syngeneic model are investigated in relation to differences across the transition from hormone-dependent (HD) to hormone-independent (HI) tumor growth and the acquisition of endocrine therapy (ET) resistance (HIR tumors). Results are articulated with reported polar metabolome results to complete a metabolic picture of the above transitions and suggest markers of tumor progression and aggressiveness. Untargeted nuclear magnetic resonance metabolomics was used to analyze tumor and mammary tissue lipid extracts. Tumor progression (HD-HI-HIR) was accompanied by increased nonesterified cholesterol forms and phospholipids (phosphatidylcholine, phosphatidylethanolamine, sphingomyelins, and plasmalogens) and decreased relative contents of triglycerides and fatty acids. Predominating fatty acids became shorter and more saturated on average. These results were consistent with gradually more activated cholesterol synthesis, β-oxidation, and phospholipid biosynthesis to sustain tumor growth, as well as an increase in cholesterol (possibly oxysterol) forms. Particular compound levels and ratios were identified as potential endocrine tumor HD-HI-HIR progression markers, supporting new hypotheses to explain acquired ET resistance.

Lipid composition of blood plasma and epithelium of the jejunal mucosa in calves with dyspepsia and its correction

Enteropathology in newborn ruminants significantly affects the functional formation of the digestive tract, which induces complications in other organs and systems, reducing the resistance and productivity in recovered animals. It is also characterized by metabolic disorders, particularly lipids, which adversely affects the regenerative processes at the cellular level. The material for the study was 2-day-old calves, from which 3 groups of 6 animals each were formed. 1st group – control was made up of clinically healthy animals, 2nd group – calves with toxic dyspepsia which received traditional treatment and 3rd group – calves which were additionally orally administered a liposomal form of a 1% solution of BAD "FLP-MD". The lipid composition of blood plasma and the epithelium of the mucous membrane of the jejunum of calves was studied by the method of thin-layer chromatography on standard Silufol plates. The lipidogram of blood plasma in 30-day-old calves recovered from dyspepsia under traditional treatment regimen was characterized by dyslipidemia, which was manifested by an increase in total lipid content by 10.0% amid hypercholesterolemia and hypertriacylglycerolemia and a decrease in free fatty acids by 24.6% and phospholipids by 11.8%. Also, phosphatidylcholine and sphingomyelin content decreasesd in the blood plasma. In epithelium of the jejunal mucosa, total lipid content decreased due to total cholesterol, triacylglycerols, and phospholipids. The restoration of total lipid content and individual fractions was found in blood plasma of calves that received additionally phospholipid-containing bio-additive "FLP-MD". Among the individual phospholipids phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine prevailed. In these calves, most of the lipid components in the epithelium of the jejunal mucosa were stabilized. In the future, we plan to investigate the content of total lipids in the blood and mucous membrane of the small intestine of calves.

Lipid Deposition Profiles Influence Foreign Body Responses.

Fibrosis remains a significant cause of failure in implanted biomedical devices and early absorption of proteins on implant surfaces has been shown to be a key instigating factor. However, lipids can also regulate immune activity and their presence may also contribute to biomaterial-induced foreign body responses (FBR) and fibrosis. Here it is demonstrated that the surface presentation of lipids on implant affects FBR by influencing reactions of immune cells to materials as well as their resultant inflammatory/suppressive polarization. Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) is employed to characterize lipid deposition on implants that are surface-modified chemically with immunomodulatory small molecules. Multiple immunosuppressive phospholipids (phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine, and sphingomyelin) are all found to deposit preferentially on implants with anti-FBR surface modifications in mice. Significantly, a set of 11 fatty acids is enriched on unmodified implanted devices that failed in both mice and humans, highlighting relevance across species. Phospholipid deposition is also found to upregulate the transcription of anti-inflammatory genes in murine macrophages, while fatty acid deposition stimulated the expression of pro-inflammatory genes. These results provide further insights into how to improve the design of biomaterials and medical devices to mitigate biomaterial material-induced FBR and fibrosis.

Comparative transcriptome and lipidome reveal that a low K+ signal effectively alleviates the effect induced by Ca2+ deficiency in cotton fibers

Calcium (Ca2+) plays an important role in determining plant growth and development because it maintains cell wall and membrane integrity. Therefore, understanding the role of Ca2+ in carbon and lipid metabolism could provide insights into the dynamic changes in cell membranes and cell walls during the rapid elongation of cotton fibers. In the present study, we found that the lack of Ca2+ promoted fiber elongation and rapid ovule expansion, but it also caused tissue browning in the ovule culture system. RNA-sequencing revealed that Ca2+ deficiency induced cells to be highly oxidized, and the expression of genes related to carbon metabolism and lipid metabolism was activated significantly. All gene members of nine key enzymes involved in glycolysis were up-regulated, and glucose was significantly reduced in Ca2+ deficiency-treated tissues. Ca2+ deficiency adjusted the flowing of glycolysis metabolic. However, low K+ recovered the expression levels of glycolysis genes and glucose content caused by Ca2+ deficiency. Electrospray ionization-tandem mass spectrometry technology was applied to uncover the dynamic profile of lipidome under Ca2+ and K+ interacted conditions. Ca2+ deficiency led to the decrease of fatty acid (FA), diacylglycerol (DAG), glycolipid and the significant increase of triacylglycerol (TAG), phospholipid phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and PC (phosphatidylcholine). Low K+ restored the contents of FA, phospholipids, and glycolipids, effectively relieved the symptoms caused by Ca2+ deficiency, and recovered the development of fiber cells. This study revealed dynamic changes in transcript and metabolic levels and uncovered the signaling interaction of Ca2+ deficiency and low K+ in glycolysis and lipid metabolism during fiber development.

Synthesis and Purification of Lipid-conjugated Fluorescent pH Sensors.

Lipid-conjugated pH sensors based on fluorophores coupled to lipids are a powerful tool for monitoring pH gradients in biological microcompartments and reconstituted membrane systems. This protocol describes the synthesis of pH sensors based on amine-reactive pHrodo esters and the amino phospholipid phosphatidylethanolamine. The major features of this sensor include efficient partitioning into membranes and strong fluorescence under acidic conditions. The protocol described here can be used as a template to couple other amine-reactive fluorophores to phosphatidylethanolamines. Graphical overview Synthesis of lipid-conjugated pH sensors based on amine-reactive fluorophore esters and the aminophospholipid phosphoethanolamine (PE).

Multiple pathways of lipid dysregulation in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis is a rapidly progressing neurodegenerative disease characterized by the degeneration of motor neurons and loss of various muscular functions. Dyslipidaemia is prevalent in amyotrophic lateral sclerosis with aberrant changes mainly in cholesterol ester and triglyceride. Despite this, little is known about global lipid changes in amyotrophic lateral sclerosis or in relation to disease progression. The present study incorporated a longitudinal lipidomic analysis of amyotrophic lateral sclerosis serum with a comparison with healthy controls using advanced liquid chromatography-mass spectrometry. The results established that diglyceride, the precursor of triglyceride, was enriched the most, while ceramide was depleted the most in amyotrophic lateral sclerosis compared with controls, with the diglyceride species (18:1/18:1) correlating significantly to neurofilament light levels. The prenol lipid CoQ8 was also decreased in amyotrophic lateral sclerosis and correlated to neurofilament light levels. Most interestingly, the phospholipid phosphatidylethanolamine and its three derivatives decreased with disease progression, in contrast to changes with normal ageing. Unsaturated lipids that are prone to lipid peroxidation were elevated with disease progression with increases in the formation of toxic lipid products. Furthermore, in vitro studies revealed that phosphatidylethanolamine synthesis modulated TARDBP expression in SH-SY5Y neuronal cells. Finally, diglyceride, cholesterol ester and ceramide were identified as potential lipid biomarkers for amyotrophic lateral sclerosis diagnosis and monitoring disease progression. In summary, this study represents a longitudinal lipidomics analysis of amyotrophic lateral sclerosis serum and has provided new insights into multiple pathways of lipid dysregulation in amyotrophic lateral sclerosis.

Fat body phospholipid state dictates hunger-driven feeding behavior.

Diet-induced obesity leads to dysfunctional feeding behavior. However, the precise molecular nodes underlying diet-induced feeding motivation dysregulation are poorly understood. The fruit fly is a simple genetic model system yet displays significant evolutionary conservation to mammalian nutrient sensing and energy balance. Using a longitudinal high-sugar regime in Drosophila, we sought to address how diet-induced changes in adipocyte lipid composition regulate feeding behavior. We observed that subjecting adult Drosophila to a prolonged high-sugar diet degrades the hunger-driven feeding response. Lipidomics analysis reveals that longitudinal exposure to high-sugar diets significantly alters whole-body phospholipid profiles. By performing a systematic genetic screen for phospholipid enzymes in adult fly adipocytes, we identify Pect as a critical regulator of hunger-driven feeding. Pect is a rate-limiting enzyme in the phosphatidylethanolamine (PE) biosynthesis pathway and the fly ortholog of human PCYT2. We show that disrupting Pect activity only in the Drosophila fat cells causes insulin resistance, dysregulated lipoprotein delivery to the brain, and a loss of hunger-driven feeding. Previously human studies have noted a correlation between PCYT2/Pect levels and clinical obesity. Now, our unbiased studies in Drosophila provide causative evidence for adipocyte Pect function in metabolic homeostasis. Altogether, we have uncovered that PE phospholipid homeostasis regulates hunger response.

O074 Metabolic phenotyping in diabetic foot ulceration

Abstract Introduction Diabetic foot ulceration is a devasting complication of diabetes contributing to significant morbidity. Delayed wound healing leads to limb loss and associated stress, anxiety and depression. Apart from systemic inflammatory markers and qualitative assessment of the ulcers, there is no molecular biomarker that can help prognosticate the fate of a diabetic foot ulcer. Metabonomics is a powerful toolset employed to describe metabolic signatures of diabetes in various biological systems. The aim of this systematic review is to summarise the existing evidence on the subject. Methods A systematic review was performed following a predefined protocol. Searches of Embase and MEDLINE by two independent authors, retrieved 292 articles, of which two were included in this study. A qualitative synthesis was performed due to heterogeneity between the studies. Result Two articles pertaining to metabonomics in diabetic foot ulcers were included. One study found that phospholipids (phosphatidylcholine, phosphatidylethanolamine and lysophosphatidylethanolamine) were associated with the development of diabetic foot ulcers. In the second study, amino acids such as arginine, isoleucine, leucine and threonine were found to be in greater concentration in the healed ulcer group as compared to the non-healed ulcer group. Conclusion The studies have highlighted disruption in the phospholipid pathway. They also suggest that specific amino acids are indeed deficient in non-healing ulcers. There is limited published literature on the application of metabolic phenotyping platforms in DFU. The methodology is heterogeneous and hence not directly comparable. Further studies are needed that utilize a biological approach, standardized design and additionally have translational application. Take-home message Diabetic foot ulcer healing is not fully understood. More study designs using metabolic phenotyping should be developed as they provide the most patient specific phenotype.

Yeast Pah1 PA phosphatase contains a novel domain within its N‐terminal intrinsically disordered region

Pah1 PA phosphatase catalyzes the dephosphorylation of PA to produce diacylglycerol. In yeast and higher eukaryotes, the diacylglycerol produced in the reaction is used for the synthesis of triacylglycerol or the membrane phospholipids phosphatidylcholine and phosphatidylethanolamine. Pah1 is inactive as a phosphorylated enzyme in the cytosol and becomes active after its recruitment and dephosphorylation by the ER‐associated Nem1‐Spo7 protein phosphatase complex. Conserved N‐LIP and HAD‐like domains are required for PA phosphatase activity and a conserved tryptophan within the WRDPLVDID domain is required for its in vivo function in lipid metabolism. Intrinsically disordered regions, which are located between the conserved catalytic domains and at the C terminus, contain multiple sites for phosphorylation and regulation of Pah1 location and function. Prediction of Pah1 structure by AlphaFold identifies a novel domain contained within the N‐terminal intrinsically disordered region for which its function is unknown. A truncation mutant that lacks amino acid residues 186‐266 have been constructed and expressed in a pah1D and pah1D nem1D mutants to assess the function of the novel domain for regulating Pah1 phosphorylation, recruitment and dephosphorylation by the Nem1‐Spo7 protein phosphatase complex, and function in lipid metabolism.

Endo- and Exometabolome Crosstalk in Mesenchymal Stem Cells Undergoing Osteogenic Differentiation.

This paper describes, for the first time to our knowledge, a lipidome and exometabolome characterization of osteogenic differentiation for human adipose tissue stem cells (hAMSCs) using nuclear magnetic resonance (NMR) spectroscopy. The holistic nature of NMR enabled the time-course evolution of cholesterol, mono- and polyunsaturated fatty acids (including ω-6 and ω-3 fatty acids), several phospholipids (phosphatidylcholine, phosphatidylethanolamine, sphingomyelins, and plasmalogens), and mono- and triglycerides to be followed. Lipid changes occurred almost exclusively between days 1 and 7, followed by a tendency for lipidome stabilization after day 7. On average, phospholipids and longer and more unsaturated fatty acids increased up to day 7, probably related to plasma membrane fluidity. Articulation of lipidome changes with previously reported polar endometabolome profiling and with exometabolome changes reported here in the same cells, enabled important correlations to be established during hAMSC osteogenic differentiation. Our results supported hypotheses related to the dynamics of membrane remodelling, anti-oxidative mechanisms, protein synthesis, and energy metabolism. Importantly, the observation of specific up-taken or excreted metabolites paves the way for the identification of potential osteoinductive metabolites useful for optimized osteogenic protocols.

Metabolic changes induced by TGF-β1 via reduced expression of phosphatidylserine decarboxylase during myofibroblast transition.

Metabolic alteration is increasingly recognized as an important pathogenic process that underlies fibrosis across many organ types, and metabolically targeted therapies could become important strategies for reducing fibrosis. In present study, target enzymes that are involved in changes in phospholipid metabolism during fibroblast-to-myofibroblast transition induced by transforming growth factor beta 1 (TGF-β1) were examined. Different amounts of phospholipids were found in the 2 groups. In response to TGF-β1 stimulation, 17 lipids decreased and 17 increased. The latter included the phospholipids phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylethanolamine (PE). Furthermore, among the rate-limiting enzymes that regulate these phospholipids, phosphatidylserine decarboxylase (PISD), which controls conversion of PS to PE and is localized in mitochondria, decreased in response to TGF-β1. Knockdown of PISD alone without TGF-β1 stimulation increased expression of α-smooth muscle actin mRNA and production of total collagen. Taken together, these results indicate that PISD is involved in the mechanism of fibrogenesis by regulating phospholipid metabolism.

Changes in Plasma Phospholipid Metabolism Are Associated with Clinical Manifestations of Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune disease with fibrosis of the skin and/or internal organs, causing a decrease in quality of life and survival. There is no causative therapy, and the pathophysiology of the SSc remains unclear. Studies showed that lipid metabolism was relevant for autoimmune diseases, but little is known about the role of lipids in SSc. In the present study, we sought to explore the phospholipid profile of SSc by using the lipidomics approach. We also aimed to analyze lipidomics results for different clinical manifestations of SSc. Experiments were performed using high-performance liquid chromatography coupled to mass spectrometry for the lipidomic profiling of plasma samples from patients with SSc. Our study showed, for the first time, significant changes in the level of phospholipids such as plasmalogens and sphingomyelins from the plasma of SSc patients as compared to controls. Phosphatidylcholine plasmalogens species and sphingomyelins were significantly increased in SSc patients as compared to controls. Our results also demonstrated a significant association of changes in the metabolism of phospholipids (phosphatidylcholine and phosphatidylethanolamine plasmalogens species and sphingomyelins) with different clinical manifestations of SSc. Further lipidomic studies might lead to the detection of lipids as new biomarkers or therapeutic targets of SSc.

Recombinant and endogenous ways to produce methylated phospholipids in Escherichia coli

Escherichia coli is the daily workhorse in molecular biology research labs and an important platform microorganism in white biotechnology. Its cytoplasmic membrane is primarily composed of the phospholipids phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and cardiolipin (CL). As in most other bacteria, the typical eukaryotic phosphatidylcholine (PC) is not a regular component of the E. coli membrane. PC is known to act as a substrate in various metabolic or catabolic reactions, to affect protein folding and membrane insertion, and to activate proteins that originate from eukaryotic environments. Options to manipulate the E. coli membrane to include non-native lipids such as PC might make it an even more powerful and versatile tool for biotechnology and protein biochemistry. This article outlines different strategies how E. coli can be engineered to produce PC and other methylated PE derivatives. Several of these approaches rely on the ectopic expression of genes from natural PC-producing organisms. These include PC synthases, lysolipid acyltransferases, and several phospholipid N-methyltransferases with diverse substrate and product preferences. In addition, we show that E. coli has the capacity to produce PC by its own enzyme repertoire provided that appropriate precursors are supplied. Screening of the E. coli Keio knockout collection revealed the lysophospholipid transporter LplT to be responsible for the uptake of lyso-PC, which is then further acylated to PC by the acyltransferase-acyl carrier protein synthetase Aas. Overall, our study shows that the membrane composition of the most routinely used model bacterium can readily be tailored on demand.Key points• Escherichia coli can be engineered to produce non-native methylated PE derivatives.• These lipids can be produced by foreign and endogenous proteins.• Modification of E. coli membrane offers potential for biotechnology and research.Graphical abstract

Phospholipids in Salt Stress Response.

High salinity threatens crop production by harming plants and interfering with their development. Plant cells respond to salt stress in various ways, all of which involve multiple components such as proteins, peptides, lipids, sugars, and phytohormones. Phospholipids, important components of bio-membranes, are small amphoteric molecular compounds. These have attracted significant attention in recent years due to the regulatory effect they have on cellular activity. Over the past few decades, genetic and biochemical analyses have partly revealed that phospholipids regulate salt stress response by participating in salt stress signal transduction. In this review, we summarize the generation and metabolism of phospholipid phosphatidic acid (PA), phosphoinositides (PIs), phosphatidylserine (PS), phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG), as well as the regulatory role each phospholipid plays in the salt stress response. We also discuss the possible regulatory role based on how they act during other cellular activities.