The ratio of phosphatidylcholine to phosphatidylethanolamine does not predict integrity of growing MT58 Chinese hamster ovary cells

Melatonin Mitigates Lead-Induced Oxidative Stress and Modifies Phospholipid Profile in Tobacco BY-2 Suspension Cells

Many studies have shown that melatonin (an indoleamine) is an important molecule in plant physiology. It is known that this indoleamine is crucial during plant stress responses, especially by counteracting secondary oxidative stress (efficient direct and indirect antioxidant) and switching on different defense plant strategies. In this report, we present exogenous melatonin's potential to protect lipid profile modification and membrane integrity in Nicotiana tabacum L. line Bright Yellow 2 (BY-2) cell culture exposed to lead. There are some reports of the positive effect of melatonin on animal cell membranes; ours is the first to report changes in the lipid profile in plant cells. The experiments were performed in the following variants: LS: cells cultured on unmodified LS medium-control; (ii) MEL: BY-2 cells cultured on LS medium with melatonin added from the beginning of culture; (iii) Pb: BY-2 cells cultured on LS medium with Pb2+ added on the 4th day of culture; (iv) MEL+Pb: BY-2 cells cultured on LS medium with melatonin added from the start of culture and stressed with Pb2+ added on the 4th day of culture. Lipidomic analysis of BY-2 cells revealed the presence of 40 different phospholipids. Exposing cells to lead led to the overproduction of ROS, altered fatty acid composition and increased PLD activity and subsequently elevated the level of phosphatidic acid at the cost of dropping the phosphatidylcholine. In the presence of lead, double-bond index elevation, mainly by higher quantities of linoleic (C18:2) and linolenic (C18:3) acids in the log phase of growth, was observed. In contrast, cells exposed to heavy metal but primed with melatonin showed more similarities with the control. Surprisingly, the overproduction of ROS caused of lipid peroxidation only in the stationary phase of growth, although considerable changes in lipid profiles were observed in the log phase of growth-just 4 h after lead administration. Our results indicate that the pretreatment of BY-2 with exogenous melatonin protected tobacco cells against membrane dysfunctions caused by oxidative stress (lipid oxidation), but also findings on a molecular level suggest the possible role of this indoleamine in the safeguarding of the membrane lipid composition that limited lead-provoked cell death. The presented research indicates a new mechanism of the defense strategy of plant cells generated by melatonin.

Gut microbiota-driven regulation of queen bee ovarian metabolism

With the global prevalence of Varroa mites, more and more beekeepers resort to confining the queen bee in a queen cage to control mite infestation or to breed superior and robust queen bees. However, the impact of such practices on the queen bee remains largely unknown. Therefore, we subjected the queen bees to a 21-day egg-laying restriction treatment (from the egg stage to the emergence of adult worker bees) and analyzed the queen bees' ovarian metabolites and gut microbiota after 21 days, aiming to assess the queen bees' quality and assist beekeepers in better hive management. Our findings revealed a significant reduction in the relative expression levels of Vg and Hex110 genes in the ovaries of egg laying-restricted queen bees compared to unrestricted egg-laying queens. The diversity of gut microbiota in the queen bee exhibited a notable decrease, accompanied by corresponding changes in the core bacteria of the microbial community, the relative abundance of Lactobacillus and Bifidobacterium increased from 22.34% to 53.14% (P = 0.01) and from 0.053% to 0.580% (P = 0.04), respectively. The relative abundance of Bombella decreased from 25.85% to 1.720% (P = 0.002). Following egg-laying restriction, the activity of the queen bee's ovaries decreased, while the metabolism of glycerophospholipids remained or stored more lipid molecules, awaiting environmental changes for the queen bee to resume egg laying promptly. Furthermore, we observed that Bombella in the queen bee's gut may regulate the queen's ovarian metabolism through tryptophan metabolism. These findings provide novel insights into the interplay among queen egg laying, gut microbiota, and ovarian metabolism. IMPORTANCE With Varroa mite infestation, beekeepers often confine the queen bee in cages for control or breeding. However, the impact on the queen bee is largely unknown. We evaluated queen bee quality by restricting egg laying and analyzing ovarian metabolites and gut microbiota. In this study, we provided a comprehensive explanation of the expression of ovarian genes, the diversity of gut microbiota, and changes in ovarian metabolism in the queen bee. Through integrated analysis of the queen bee's gut microbiota and ovarian metabolism, we discovered that the gut microbiota can regulate the queen bee's ovarian metabolism. These findings provide valuable insights into the interplay among egg laying, gut microbiota, and the reproductive health of the queen bee. Understanding these relationships can contribute to the development of better strategies for Varroa mite control and queen bee breeding.

Metabolomic analysis of maternal mid-gestation plasma and cord blood in autism spectrum disorders

The discovery of prenatal and neonatal molecular biomarkers has the potential to yield insights into autism spectrum disorder (ASD) and facilitate early diagnosis. We characterized metabolomic profiles in ASD using plasma samples collected in the Norwegian Autism Birth Cohort from mothers at weeks 17-21 gestation (maternal mid-gestation, MMG, n = 408) and from children on the day of birth (cord blood, CB, n = 418). We analyzed associations using sex-stratified adjusted logistic regression models with Bayesian analyses. Chemical enrichment analyses (ChemRICH) were performed to determine altered chemical clusters. We also employed machine learning algorithms to assess the utility of metabolomics as ASD biomarkers. We identified ASD associations with a variety of chemical compounds including arachidonic acid, glutamate, and glutamine, and metabolite clusters including hydroxy eicospentaenoic acids, phosphatidylcholines, and ceramides in MMG and CB plasma that are consistent with inflammation, disruption of membrane integrity, and impaired neurotransmission and neurotoxicity. Girls with ASD have disruption of ether/non-ether phospholipid balance in the MMG plasma that is similar to that found in other neurodevelopmental disorders. ASD boys in the CB analyses had the highest number of dysregulated chemical clusters. Machine learning classifiers distinguished ASD cases from controls with area under the receiver operating characteristic (AUROC) values ranging from 0.710 to 0.853. Predictive performance was better in CB analyses than in MMG. These findings may provide new insights into the sex-specific differences in ASD and have implications for discovery of biomarkers that may enable early detection and intervention.

Circadian Regulation and Clock-Controlled Mechanisms of Glycerophospholipid Metabolism from Neuronal Cells and Tissues to Fibroblasts

Along evolution, living organisms developed a precise timekeeping system, circadian clocks, to adapt life to the 24-h light/dark cycle and temporally regulate physiology and behavior. The transcriptional molecular circadian clock and metabolic/redox oscillator conforming these clocks are present in organs, tissues, and even in individual cells, where they exert circadian control over cellular metabolism. Disruption of the molecular clock may cause metabolic disorders and higher cancer risk. The synthesis and degradation of glycerophospholipids (GPLs) is one of the most highly regulated metabolisms across the 24-h cycle in terms of total lipid content and enzyme expression and activity in the nervous system and individual cells. Lipids play a plethora of roles (membrane biogenesis, energy sourcing, signaling, and the regulation of protein-chromatin interaction, among others), making control of their metabolism a vital checkpoint in the cellular organization of physiology. An increasing body of evidence clearly demonstrates an orchestrated and sequential series of events occurring in GPL metabolism across the 24-h day in diverse retinal cell layers, immortalized fibroblasts, and glioma cells. Moreover, the clock gene Per1 and other circadian-related genes are tightly involved in the regulation of GPL synthesis in quiescent cells. However, under proliferation, the metabolic oscillator continues to control GPL metabolism of brain cancer cells even after molecular circadian clock disruption, reflecting the crucial role of the temporal metabolism organization in cell preservation. The aim of this review is to examine the control exerted by circadian clocks over GPL metabolism, their synthesizing enzyme expression and activities in normal and tumorous cells of the nervous system and in immortalized fibroblasts.

One-Carbon Metabolism in Fatty Liver Disease and Fibrosis: One-Carbon to Rule Them All

Nonalcoholic fatty liver disease (NAFLD) is a term used to characterize a range of disease states that involve the accumulation of fat in the liver but are not associated with excessive alcohol consumption. NAFLD is a prevalent disease that can progress to organ damage like liver cirrhosis and hepatocellular carcinoma. Many animal models have demonstrated that one-carbon metabolism is strongly associated with NAFLD. Phosphatidylcholine is an important phospholipid that affects hepatic lipid homeostasis and de novo synthesis of this phospholipid is associated with NAFLD. However, one-carbon metabolism serves to support all cellular methylation reactions and catabolism of methionine, serine, glycine, choline, betaine, tryptophan, and histidine. Several different pathways within one-carbon metabolism that play important roles in regulating energy metabolism and immune function have received less attention in the study of fatty liver disease and fibrosis. This review examines what we have learned about hepatic lipid metabolism and liver damage from the study of one-carbon metabolism thus far and highlights unexplored opportunities for future research.

Liver and plasma lipid changes induced by cyclic fatty acid monomers from heated vegetable oil in the rat

Cyclic fatty acid monomers (CFAM) generated through domestic or industrial heating of vegetable oils may alter liver enzymes and induce hepatomegaly and steatosis, but the underlying mechanisms are not clearly understood. This study aimed to assess the effects of CFAM on liver and plasma lipids and to determine whether these effects are modulated by dietary lipids. Thirty-six (36) male Wistar rats were fed either of the four isoenergetic diets consisting of canola oil or soybean oil with/without 500 mg/100 g CFAM of total fat for 28 days. Rats fed CFAM had higher liver total lipids (p = 0.03) and triacylglycerols (TAG) (p = 0.02), but less hepatic phosphatidylcholine (p = 0.02) compared to those fed the non-CFAM diets. CFAM did not alter liver phosphatidylethanolamine N-methyltransferase (PEMT) activity and CTP: phosphocholine cytidylyltransferase (CT-α) protein levels. Rats fed CFAM diets had higher levels of plasma total cholesterol (TC), VLDL + LDL cholesterol, higher ratio of TC to HDL cholesterol, and lower levels of HDL cholesterol compared with rats fed non-CFAM diets (p < 0.05). Plasma alanine transaminase (ALT) was decreased with CFAM, but plasma insulin, glucose, and TAG did not vary among the four diet groups (p < 0.05). Rats fed canola oil and CFAM had higher plasma levels of aspartate transaminase (AST) and AST/ALT ratio compared with the other three diet groups. These results indicate that CFAM may provoke an accumulation of TAG in the liver related to a decrease in phosphatidylcholine (PC) levels, but the effect of CFAM on PC concentrations may not occur through impairment of the two main PC biosynthesis pathways.

A lipidomic approach to understand copper resilience in oyster Crassostrea hongkongensis

Copper (Cu) can cause oxidative stress and inflammatory responses, and there is arising evidence between Cu toxicity and lipid disturbance. In this study, we examined the relationships between Cu exposure and lipid metabolism in an estuarine oyster (Crassostrea hongkongensis) and aimed to understand the effects and resilience strategies of Cu on oyster metabolism. We exposed the oysters to waterborne Cu (10 and 50 μg/L) and measured the physiological changes (condition index and clearance rate), lipid accumulation and lipid peroxidation in the oysters. We found more altered lipid responses in oysters exposed to a lower Cu concentration (10 μg/L), and speculated that oysters exposed to 50 μg/L may upregulate the defenses. We further evaluated the changes in lipidome profiling of the Cu-exposed oysters in aspects of membrane dynamics, lipid signaling and energy metabolism. We documented the phospholipid remodeling as well as quick modulation in inflammatory responses and extensive vesicle formation for subcellular compartmentalization and autophagosome formation, as well as the possible impacts on mitochondrial bioenergetics in the Cu-exposed oysters. The lipidomics approach provided a comprehensive lipid profile of possible alteration by Cu exposure. In combination with other omics approaches, it may be possible to elucidate the pathways and mechanisms in stress acclimation and resilience associated between Cu contamination and lipid metabolism.

Heterologous expression of CTP:phosphocholine cytidylyltransferase from Plasmodium falciparum rescues Chinese Hamster Ovary cells deficient in the Kennedy phosphatidylcholine biosynthesis pathway

The plasmodial CTP:phosphocholine cytidylyltransferase (PfCCT) is a promising antimalarial target, which can be inhibited to exploit the need for increased lipid biosynthesis during the erythrocytic life stage of Plasmodium falciparum. Notable structural and regulatory differences of plasmodial and mammalian CCTs offer the possibility to develop species-specific inhibitors. The aim of this study was to use CHO-MT58 cells expressing a temperature-sensitive mutant CCT for the functional characterization of PfCCT. We show that heterologous expression of wild type PfCCT restores the viability of CHO-MT58 cells at non-permissive (40 °C) temperatures, whereas catalytically perturbed or structurally destabilized PfCCT variants fail to provide rescue. Detailed in vitro characterization indicates that the H630N mutation diminishes the catalytic rate constant of PfCCT. The flow cytometry-based rescue assay provides a quantitative readout of the PfCCT function opening the possibility for the functional analysis of PfCCT and the high throughput screening of antimalarial compounds targeting plasmodial CCT.

CTP:phosphocholine cytidylyltransferase: Function, regulation, and structure of an amphitropic enzyme required for membrane biogenesis

CTP:phosphocholine cytidylyltransferase (CCT) catalyzes a rate-limiting and regulated step in the CDP-choline pathway for the synthesis of phosphatidylcholine (PC) and PC-derived lipids. Control of CCT activity is multi-layered, and includes direct regulation by reversible membrane binding involving a built-in lipid compositional sensor. Thus CCT contributes to phospholipid compositional homeostasis. CCT also modifies the curvature of its target membrane. Knowledge of CCT structure and regulation of its catalytic function are relatively advanced compared to many lipid metabolic enzymes, and are reviewed in detail. Recently the genetic origins of two human developmental and lipogenesis disorders have been traced to mutations in the gene for CCTα.

Molecular Mechanism for the Thermo-Sensitive Phenotype of CHO-MT58 Cell Line Harbouring a Mutant CTP:Phosphocholine Cytidylyltransferase

Control and elimination of malaria still represents a major public health challenge. Emerging parasite resistance to current therapies urges development of antimalarials with novel mechanism of action. Phospholipid biosynthesis of the Plasmodium parasite has been validated as promising candidate antimalarial target. The most prevalent de novo pathway for synthesis of phosphatidylcholine is the Kennedy pathway. Its regulatory and often also rate limiting step is catalyzed by CTP:phosphocholine cytidylyltransferase (CCT). The CHO-MT58 cell line expresses a mutant variant of CCT, and displays a thermo-sensitive phenotype. At non-permissive temperature (40°C), the endogenous CCT activity decreases dramatically, blocking membrane synthesis and ultimately leading to apoptosis. In the present study we investigated the impact of the analogous mutation in a catalytic domain construct of Plasmodium falciparum CCT in order to explore the underlying molecular mechanism that explains this phenotype. We used temperature dependent enzyme activity measurements and modeling to investigate the functionality of the mutant enzyme. Furthermore, MS measurements were performed to determine the oligomerization state of the protein, and MD simulations to assess the inter-subunit interactions in the dimer. Our results demonstrate that the R681H mutation does not directly influence enzyme catalytic activity. Instead, it provokes increased heat-sensitivity by destabilizing the CCT dimer. This can possibly explain the significance of the PfCCT pseudoheterodimer organization in ensuring proper enzymatic function. This also provide an explanation for the observed thermo-sensitive phenotype of CHO-MT58 cell line.

The follicular microenviroment as a predictor of pregnancy: MALDI-TOF MS lipid profile in cumulus cells

PURPOSE

This research proposed to study the changes in lipid composition in cumulus cells (CCs) from women who achieved pregnancy compared with women who did not, after in vitro fertilization treatment. This approach has the potential to provide novel information on the lipid metabolism of the CCs and as an additional method to predict pregnancy.

METHOD

Fifty-four samples from couples with tubal and male factor infertility and where the female partner was age 35 or younger were divided in two groups according to their level of hCG 14 days after embryo transfer as follows: (1) 23 samples in pregnant group and (2) 31 samples in non-pregnant group. Lipid extraction was performed by the Bligh-Dyer protocol, and lipid profiles were obtained by MALDI-TOF MS. Mass spectra data were processed with MassLynx, and statistical analysis was performed using MarkerLynx extended statistic. OPLS-DA model was built.

RESULTS

S-plot Analysis revealed three ions as potential markers in the pregnant group, and five ions in the non-pregnant group. These ions were identified in the human metabolome database (HMDB) as phosphatidylcholine in the pregnant group and as phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol species in the non-pregnant group. These lipids might be involved in cell proliferation and differentiation, apoptosis and GAP junction regulation.

CONCLUSION

We conclude that MALDI-TOF MS can be used as an informative and fast analytical strategy to obtain and study the lipid profile of cumulus cells and can potentially be used as a supporting tool to predict pregnancy based on the metabolic state of the CCs.