Update on glycerol-3-phosphate acyltransferases: the roles in the development of insulin resistance

Unlocking the Potential of l-α-Glycerylphosphorylcholine: From Metabolic Pathways to Therapeutic Applications

l-α-Glycerylphosphorylcholine (GPC), also known as choline alphoscerate or α-glycerophosphorylcholine, serves as both a pharmaceutical product and a dietary supplement. Through its metabolic pathways, GPC acts as the precursor not only of choline and acetylcholine but also of various phospholipids. Extensive preclinical and clinical evidence demonstrates that GPC effectively alleviates cognitive impairment associated with Alzheimer's disease, vascular dementia, cerebral ischemia, stress, and epilepsy, among other conditions. Additionally, GPC has beneficial effects on such conditions and measures as ischemic/hypoxic conditions, ionizing radiation-induced damage, exercise performance, growth hormone release, and liver damage. As well as facilitating cholinergic neurotransmission, evidence also indicates GPC, among other activities, also can promote γ-aminobutyric acid release, enhance protein kinase C activity, facilitate hippocampal neurogenesis, upregulate neurotrophic factors, and inhibit inflammation. In preclinical studies, results indicate that GPC is not genotoxic in vitro or in vivo. Extensive human studies indicate GPC causes no severe adverse effects. Possible risks of atherosclerosis and stroke await necessary validation. In this review, the GPC-related metabolic pathways, pharmacological effects, mechanisms of action, and safety evaluation are discussed with the aim of providing a comprehensive understanding of GPC.

Exploring the fate of 6PPD in zebrafish (Danio rerio): Understanding toxicokinetics, biotransformation mechanisms, and metabolomic profiling at environmentally relevant levels

In recent years, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) has attracted significant attention in environmental science, yet its behavior in biological systems remains poorly understood. This study involved a 28-day zebrafish exposure experiment at three concentrations (2, 20, and 200 μg/L), to investigate its physiologically based toxicokinetic (PBTK) properties, the formation of biotransformation products, and the metabolic characteristics of liver tissue. The results indicated that the liver and intestines are key organs for 6PPD accumulation, with tissue-specific distribution patterns. The biotransformation of 6PPD in the liver involves various phase I and phase II metabolic reactions, including hydroxylation, N-dealkylation, and sulfation processes. Furthermore, Metabolomics analysis revealed substantial changes in both the diversity and abundance of liver metabolites with increasing 6PPD concentrations, particularly in key biological processes such as lipid metabolism, amino acid metabolism, and redox balance. Notably, significant disruptions in sphingolipid and glycerophospholipid pathways suggest 6PPD may impair membrane fluidity and stability, potentially leading to membrane damage and dysfunction. Overall, this study provides crucial insights into the biological behavior of 6PPD in zebrafish, contributing essential knowledge for its ecotoxicological evaluation.

Analysis and Comparison of Lipids in Monascus-Fermented Cheese from Different Ripening Periods Based on UHPLC-QTRAP MS Quantitative Lipidomics

Monascus-fermented cheese (MC) is a new cheese product that undergoes a multistrain fermentation process, which results in unique flavor qualities. Lipid metabolism plays an important role in the flavor formation of MC. To clarify the lipid composition of MC and the changes in lipid composition at four ripening periods, this study resolved the lipid profiles of MC by using UHPLC-QTRAP MS. The results identified 21 lipid classes and 748 lipid species, 72 of which were significantly different (VIP > 1, p < 0.01, |log 2FC| > 1). Additionally, 83 relevant metabolic pathways were enriched. Based on the enriched metabolic pathways and lipid changes, the pathways of differential lipid formation in MC were mapped. The results of this study comprehensively characterize the changes in lipids during the ripening process of MC, which can be used in the future to deeply analyze the mechanism of flavor formation in MC.

Fate of polystyrene micro- and nanoplastics in zebrafish liver cells: Influence of protein corona on transport, oxidative stress, and glycolipid metabolism

Micro- and nanoplastics (MNPs) form protein corona (PC) upon contact with biological fluids, but their impact on the intracellular transport, distribution, and toxicity of MNPs remains unclear. Fetal bovine serum (FBS) and bovine serum albumin (BSA) were used to simulate in vivo environment, this study explored their influence on the transport and toxicity of polystyrene (PS) MNPs in zebrafish liver (ZFL) cells. Results showed PS MNPs were wrapped by proteins into stable complexes. Nanoparticles (NP, 50 nm) and their protein complexes (NP@PC) were internalized by cells within 6 h, with PC formation enhancing NP uptake. NP primarily entered cells through clathrin- and caveolae-mediated endocytosis, while NP@PC via clathrin-mediated pathways. Internalized particles were predominantly in lysosomes where PC degraded and some were also in mitochondria. Eventually, particles were expelled from cells through energy-dependent lysosomal pathways and energy-independent membrane penetration mechanisms. Notably, PC formation limited the clearance of NP. In toxicity, NP had a more severe impact than microplastics (MP, 5 μm). FBS more effectively mitigated PS MNPs-induced reactive oxygen species accumulation, subcellular structural damage, and dysregulation of glycolipid metabolism than BSA did. This study elucidates the modulatory role of PC on biological effects of MNPs, providing safety and risk management strategies.

Diacylglycerol Kinases and Its Role in Lipid Metabolism and Related Diseases

Lipids are essential components of eukaryotic membranes, playing crucial roles in membrane structure, energy storage, and signaling. They are predominantly synthesized in the endoplasmic reticulum (ER) and subsequently transported to other organelles. Diacylglycerol kinases (DGKs) are a conserved enzyme family that phosphorylate diacylglycerol (DAG) to produce phosphatidic acid (PA), both of which are key intermediates in lipid metabolism and second messengers involved in numerous cellular processes. Dysregulation of DGK activity is associated with several diseases, including cancer and metabolic disorders. In this review, we provide a comprehensive overview of DGK types, functions, cellular localization, and their potential as therapeutic targets. We also discuss DGKs' roles in lipid metabolism and their physiological functions and related diseases.

MS-DIAL 5 multimodal mass spectrometry data mining unveils lipidome complexities

Lipidomics and metabolomics communities comprise various informatics tools; however, software programs handling multimodal mass spectrometry (MS) data with structural annotations guided by the Lipidomics Standards Initiative are limited. Here, we provide MS-DIAL 5 for in-depth lipidome structural elucidation through electron-activated dissociation (EAD)-based tandem MS and determining their molecular localization through MS imaging (MSI) data using a species/tissue-specific lipidome database containing the predicted collision-cross section values. With the optimized EAD settings using 14 eV kinetic energy, the program correctly delineated lipid structures for 96.4% of authentic standards, among which 78.0% had the sn-, OH-, and/or C = C positions correctly assigned at concentrations exceeding 1 μM. We showcased our workflow by annotating the sn- and double-bond positions of eye-specific phosphatidylcholines containing very-long-chain polyunsaturated fatty acids (VLC-PUFAs), characterized as PC n-3-VLC-PUFA/FA. Using MSI data from the eye and n-3-VLC-PUFA-supplemented HeLa cells, we identified glycerol 3-phosphate acyltransferase as an enzyme candidate responsible for incorporating n-3 VLC-PUFAs into the sn1 position of phospholipids in mammalian cells, which was confirmed using EAD-MS/MS and recombinant proteins in a cell-free system. Therefore, the MS-DIAL 5 environment, combined with optimized MS data acquisition methods, facilitates a better understanding of lipid structures and their localization, offering insights into lipid biology.

Lipid Dynamics in Pancreatic β-Cells: Linking Physiology to Diabetes Onset

Significance: Glucose-induced lipid metabolism is essential for preserving functional β-cells, and its disruption is linked to type 2 diabetes (T2D) development. Lipids are an integral part of the cells playing an indispensable role as structural components, energy storage molecules, and signals. Recent Advances: Glucose presence significantly impacts lipid metabolism in β-cells, where fatty acids are primarily synthesized de novo and/or are transported from the bloodstream. This process is regulated by the glycerolipid/free fatty acid cycle, which includes lipogenic and lipolytic reactions producing metabolic coupling factors crucial for insulin secretion. Disrupted lipid metabolism involving oxidative stress and inflammation is a hallmark of T2D. Critical Issues: Lipid metabolism in β-cells is complex involving multiple simultaneous processes. Exact compartmentalization and quantification of lipid metabolism and its intermediates, especially in response to glucose or chronic hyperglycemia, are essential. Current research often uses non-physiological conditions, which may not accurately reflect in vivo situations. Future Directions: Identifying and quantifying individual steps and their signaling, including redox, within the complex fatty acid and lipid metabolic pathways as well as the metabolites formed during acute versus chronic glucose stimulation, will uncover the detailed mechanisms of glucose-stimulated insulin secretion. This knowledge is crucial for understanding T2D pathogenesis and identifying pharmacological targets to prevent this disease. Antioxid. Redox Signal. 41, 865-889.

Functional analysis of the GPAT4 gene mutation predicted to affect splicing

The GPAT4 gene is considered as a potential functional candidate for single nucleotide polymorphism (SNP) studies in dairy cattle breeding due to its association with dairy performance in cattle by encoding an enzyme responsible for the presence of diacylglycerols and triacylglycerols in milk. Using the example of the GPAT4 gene, we applied the minigene splicing assay to analyze the functional consequences of its variant that was predicted to affect normal splicing. The results of functional analysis revealed the sequence variations (rs442541537), transfection experiments in a wild type and mutant cell line model system demonstrated that the investigated mutation in the second intron of the GPAT4 gene was responsible for the presence of a second exon in mature messenger RNA (mRNA). The cases of its absence in the spliced mature mRNA transcript resulted in a truncated dysfunctional protein due to the appearance of a stop codon. Thus, the discovered SNP led to alternative splicing in pre-mRNA by the 'cassette exon' ('exon skipping') mechanism. The studied mutation can potentially be a molecular genetic marker for alternative splicing for the GPAT4 gene and, therefore contributes to economic benefits in cattle breeding programs.

Identification of QTL for Alkylresorcinols in Wheat and Development of KASP Markers for Marker-Assisted Selection of Health-Promoting Varieties

This study evaluated alkylresorcinol concentration (ARC) in recombinant inbred lines (RILs) from the cross of Zhongmai 578 and Jimai 22 in three environments. ARC exhibited a continuous distribution ranging from 337.4 to 758.0, 495.4-768.0, and 456.3-764.7 μg/g, respectively, in three environments. Analysis of variance (ANOVA) indicated significant (P < 0.001) impacts of genotypes, environments, and their interactions. The broad-sense heritability of ARC was 0.76. Genome-wide linkage mapping analysis identified four stable quantitative trait loci (QTL) for ARC on chromosomes 2A, 3A, 4D, and 7A. Kompetitive allele-specific PCR (KASP) marker of each QTL was developed and validated in 206 representative wheat varieties. Wheat varieties harboring 0, 1, 2, 3, and 4 favorable alleles had ARC of 499.1, 587.8, 644.7, 668.5, and 711.1 μg/g, respectively. This study suggests that combining multiple minor-effect QTL through KASP markers can serve as an effective strategy for breeding high-ARC wheat, thereby enhancing innovations in functional food production.

Protein kinase CK2: An emerging regulator of cellular metabolism

The protein kinase casein kinase 2 (CK2) exerts its influence on the metabolism of three major cellular substances by phosphorylating essential protein molecules involved in various cellular metabolic pathways. These substances include hormones, especially insulin, rate-limiting enzymes, transcription factors of key genes, and cytokines. This regulatory role of CK2 is closely tied to important cellular processes such as cell proliferation and apoptosis. Additionally, tumor cells undergo metabolic reprogramming characterized by aerobic glycolysis, accelerated lipid β-oxidation, and abnormally active glutamine metabolism. In this context, CK2, which is overexpressed in various tumors, also plays a pivotal role. Hence, this review aims to summarize the regulatory mechanisms of CK2 in diverse metabolic pathways and tumor development, providing novel insights for the diagnosis, treatment, and prognosis of metabolism-related diseases and cancers.

Pre-eclamptic foetal programming predisposes offspring to hepatic steatosis via DNA methylation

OBJECTIVES

Gamete and embryo-foetal origins of adult diseases hypothesis proposes that adulthood chronic disorders are associated with adverse foetal and early life traits. Our study aimed to characterise developmental changes and underlying mechanisms of metabolic disorders in offspring of pre-eclampsia (PE) programmed pregnancy.

METHODS

Nω-Nitro-l-arginine methyl ester hydrochloride (L-NAME) induced pre-eclampsia-like C57BL/6J mouse model was used. Lipid profiling, histological morphology, indirect calorimetry, mRNA sequencing, and pyrosequencing were performed on PE offspring of both young and elderly ages.

RESULTS

PE offspring exhibited increased postnatal weight gain, hepatic lipid accumulation, enlarged adipocytes, and impaired energy balance that continued to adulthood. Integrated RNA sequencing of foetal and 52-week-old livers revealed that the differentially expressed genes were mainly enriched in lipid metabolism, including glycerol-3-phosphate acyl-transferase 3 (Gpat3), a key enzyme for de novo synthesis of triglycerides (TG), and carnitine palmitoyltransferase-1a (Cpt1a), a key transmembrane enzyme that mediates fatty acid degradation. Pyrosequencing of livers from PE offspring identified hypomethylated and hypermethylated regions in Gpat3 and Cpt1a promoters, which were associated with upregulated and downregulated expressions of Gpat3 and Cpt1a, respectively. These epigenetic alterations are persistent and consistent from the foetal stage to adulthood in PE offspring.

CONCLUSION

These findings suggest a methylation-mediated epigenetic mechanism for PE-induced intergenerational lipid accumulation, impaired energy balance and obesity in offspring, and indicate the potential benefits of early interventions in offspring exposed to maternal PE to reduce their susceptibility to metabolic disorder in their later life.

Glycerol 3-phosphate dehydrogenases (1 and 2) in cancer and other diseases

The glycerol 3-phosphate shuttle (GPS) is composed of two different enzymes: cytosolic NAD+-linked glycerol 3-phosphate dehydrogenase 1 (GPD1) and mitochondrial FAD-linked glycerol 3-phosphate dehydrogenase 2 (GPD2). These two enzymes work together to act as an NADH shuttle for mitochondrial bioenergetics and function as an important bridge between glucose and lipid metabolism. Since these genes were discovered in the 1960s, their abnormal expression has been described in various metabolic diseases and tumors. Nevertheless, it took a long time until scientists could investigate the causal relationship of these enzymes in those pathophysiological conditions. To date, numerous studies have explored the involvement and mechanisms of GPD1 and GPD2 in cancer and other diseases, encompassing reports of controversial and non-conventional mechanisms. In this review, we summarize and update current knowledge regarding the functions and effects of GPS to provide an overview of how the enzymes influence disease conditions. The potential and challenges of developing therapeutic strategies targeting these enzymes are also discussed.

Metabolome and Transcriptome Association Analysis Reveals Mechanism of Synthesis of Nutrient Composition in Quinoa (Chenopodium quinoa Willd.) Seeds

Quinoa (Chenopodium quinoa Willd.) seeds are rich in nutrition, superior to other grains, and have a high market value. However, the biosynthesis mechanisms of protein, starch, and lipid in quinoa grain are still unclear. The objective of this study was to ascertain the nutritional constituents of white, yellow, red, and black quinoa seeds and to employ a multi-omics approach to analyze the synthesis mechanisms of these nutrients. The findings are intended to furnish a theoretical foundation and technical support for the biological breeding of quinoa in China. In this study, the nutritional analysis of white, yellow, red, and black quinoa seeds from the same area showed that the nutritional contents of the quinoa seeds were significantly different, and the protein content increased with the deepening of color. The protein content of black quinoa was the highest (16.1 g/100 g) and the lipid content was the lowest (2.7 g/100 g), among which, linoleic acid was the main fatty acid. A combined transcriptome and metabolome analysis exhibited that differentially expressed genes were enriched in "linoleic acid metabolism", "unsaturated fatty acid biosynthesis", and "amino acid biosynthesis". We mainly identified seven genes involved in starch synthesis (LOC110716805, LOC110722789, LOC110738785, LOC110720405, LOC110730081, LOC110692055, and LOC110732328); five genes involved in lipid synthesis (LOC110701563, LOC110699636, LOC110709273, LOC110715590, and LOC110728838); and nine genes involved in protein synthesis (LOC110710842, LOC110720003, LOC110687170, LOC110716004, LOC110702086, LOC110724454 LOC110724577, LOC110704171, and LOC110686607). The data presented in this study based on nutrient, transcriptome, and metabolome analyses contribute to an enhanced understanding of the genetic regulation of seed quality traits in quinoa, and provide candidate genes for further genetic improvements to improve the nutritional value of quinoa seeds.

The Emerging Role of LPA as an Oncometabolite

Lysophosphatidic acid (LPA) is a phospholipid that displays potent signalling activities that are regulated in both an autocrine and paracrine manner. It can be found both extra- and intracellularly, where it interacts with different receptors to activate signalling pathways that regulate a plethora of cellular processes, including mitosis, proliferation and migration. LPA metabolism is complex, and its biosynthesis and catabolism are under tight control to ensure proper LPA levels in the body. In cancer patient specimens, LPA levels are frequently higher compared to those of healthy individuals and often correlate with poor responses and more aggressive disease. Accordingly, LPA, through promoting cancer cell migration and invasion, enhances the metastasis and dissemination of tumour cells. In this review, we summarise the role of LPA in the regulation of critical aspects of tumour biology and further discuss the available pre-clinical and clinical evidence regarding the feasibility and efficacy of targeting LPA metabolism for effective anticancer therapy.

Synthesis of phospholipids in human placenta

INTRODUCTION

Placental phospholipid synthesis is critical for the expansion of the placental exchange surface area and for production of signaling molecules. Despite their importance, it is not yet established which enzymes involved in the de novo synthesis and remodeling of placental phospholipids are expressed and active in the human placenta.

METHODS

We identified phospholipid synthesis enzymes by immunoblotting in placental homogenates and immunofluorescence in placenta tissue sections. Primary human trophoblast (PHT) cells from term healthy placentas (n = 10) were cultured and exposed to 13C labeled fatty acids (16:0, 18:1 and 18:2 n-6, 22:6 n-3) for 2 and 24 h. Three phospholipid classes; phosphatidic acid, phosphatidylcholine, and lysophosphatidylcholine containing 13C fatty acids were quantified by Liquid Chromatography with tandem mass spectrometry (LC/MS-MS).

RESULTS

Acyl transferase and phospholipase enzymes were detected in human placenta homogenate and primarily expressed in the syncytiotrophoblast. Three representative 13C fatty acids (16:0, 18:1 and 18:2 n-6) were incorporated rapidly into phosphatidic acid in trophoblasts, but 13C labeled docosahexaenoic acid (DHA; 22:6 n-3) incorporation was not detected. 13C DHA was incorporated into phosphatidylcholine. Lysophosphatidylcholine containing all four 13C labeled fatty acids were found in high abundance.

CONCLUSIONS

Phospholipid synthesis and remodeling enzymes are present in the syncytiotrophoblast. 13C labeled fatty acids were rapidly incorporated into cellular phospholipids. 13C DHA was incorporated into phospholipids through the remodeling pathway rather than by de novo synthesis. These understudied pathways are highly active and critical for structure and function of the placenta.

GPAT3 deficiency attenuates corticosterone-caused hepatic steatosis and oxidative stress through GSK3β/Nrf2 signals

The development of nonalcoholic fatty liver disease (NAFLD) may worsen due to chronic stress or prolonged use of glucocorticoids. Glycerol-3-phosphate acyltransferase 3 (GPAT3), has a function in obesity and serves as a key rate-limiting enzyme that regulates triglyceride synthesis. However, the precise impact of GPAT3 on corticosterone (CORT)-induced NAFLD and its underlying molecular mechanism remain unclear. For our in vivo experiments, we utilized male and female mice that were GPAT3-/- and wild type (WT) and treated them with CORT for a duration of 4 weeks. In our in vitro experiments, we transfected AML12 cells with GPAT3 siRNA and subsequently treated them with CORT. Under CORT-treated conditions, the absence of GPAT3 greatly improved obesity and hepatic steatosis while enhancing the expression of genes involved in fatty acid oxidation, as evidenced by our findings. In addition, the deletion of GPAT3 significantly inhibited the production of reactive oxygen species (ROS), increased the expression of antioxidant genes, and recovered the mitochondrial membrane potential in AML12 cells treated with CORT. In terms of mechanism, the absence of GPAT3 encouraged the activation of the glycogen synthase kinase 3β (GSK3β)/nuclear factor-erythroid 2 related factor 2 (Nrf2) pathway, which served as a defense mechanism against liver fat accumulation and oxidative stress. Furthermore, GPAT3 expression was directly controlled at the transcriptional level by the glucocorticoid receptor (GR). Collectively, our findings suggest that GPAT3 deletion significantly alleviated hepatic steatosis and oxidative stress through promoting GSK3β/Nrf2 signaling pathways.

Drug Targeting of Acyltransferases in the Triacylglyceride and 1-O-AcylCeramide Biosynthetic Pathways

Acyltransferase enzymes (EC 2.3.) are a large group of enzymes that transfer acyl groups to a variety of substrates. This review focuses on fatty acyltransferases involved in the biosynthetic pathways of glycerolipids and sphingolipids and how these enzymes have been pharmacologically targeted in their biologic context. Glycerolipids and sphingolipids, commonly treated independently in their regulation and biologic functions, are put together to emphasize the parallelism in their metabolism and bioactive roles. Furthermore, a newly considered signaling molecule, 1-O-acylceramide, resulting from the acylation of ceramide by DGAT2 enzyme, is discussed. Finally, the implications of DGAT2 as a putative ceramide acyltransferase (CAT) enzyme, with a putative dual role in TAG and 1-O-acylceramide generation, are explored. SIGNIFICANCE STATEMENT: This manuscript reviews the current status of drug development in lipid acyltransferases. These are current targets in metabolic syndrome and other diseases, including cancer. A novel function for a member in this group of lipids has been recently reported in cancer cells. The responsible enzyme and biological implications of this added member are discussed.

Acute activation of adipocyte lipolysis reveals dynamic lipid remodeling of the hepatic lipidome

Adipose tissue is the site of long-term energy storage. During the fasting state, exercise, and cold exposure, the white adipose tissue mobilizes energy for peripheral tissues through lipolysis. The mobilization of lipids from white adipose tissue to the liver can lead to excess triglyceride accumulation and fatty liver disease. Although the white adipose tissue is known to release free fatty acids, a comprehensive analysis of lipids mobilized from white adipocytes in vivo has not been completed. In these studies, we provide a comprehensive quantitative analysis of the adipocyte-secreted lipidome and show that there is interorgan crosstalk with liver. Our analysis identifies multiple lipid classes released by adipocytes in response to activation of lipolysis. Time-dependent analysis of the serum lipidome showed that free fatty acids increase within 30 min of β3-adrenergic receptor activation and subsequently decrease, followed by a rise in serum triglycerides, liver triglycerides, and several ceramide species. The triglyceride composition of liver is enriched for linoleic acid despite higher concentrations of palmitate in the blood. To further validate that these findings were a specific consequence of lipolysis, we generated mice with conditional deletion of adipose tissue triglyceride lipase exclusively in adipocytes. This loss of in vivo adipocyte lipolysis prevented the rise in serum free fatty acids and hepatic triglycerides. Furthermore, conditioned media from adipocytes promotes lipid remodeling in hepatocytes with concomitant changes in genes/pathways mediating lipid utilization. Together, these data highlight critical role of adipocyte lipolysis in interorgan crosstalk between adipocytes and liver.

Downregulated GPD1 and MAGL protein levels as potential biomarkers for the metastasis of triple‑negative breast tumors to axillary lymph nodes

Glycerol-3-phosphate dehydrogenase (GPD1) and monoacylglycerol lipase (MAGL) levels are known to be significantly downregulated in both the tissue and serum samples of patients with triple-negative breast cancer (TNBC), compared with other BC subtypes and healthy controls. As such, the association between GPD1 and MAGL levels and lymph node metastasis was evaluated in the present study. Utilizing western blotting, lymph node protein extracts from metastasized BC subtypes were analyzed and a significant downregulation of GPD1 and MAGL protein expression levels in the lymph node metastases was demonstrated in the TNBC subtype, compared with healthy controls. This finding further highlighted the potential use of these two proteins in early BC onset and metastasis detection.

Bacterial diversity and community structure of salt pans from Goa, India

In Goa, salt production from the local salt pans is an age-old practice. These salt pans harbor a rich diversity of halophilic microbes with immense biotechnological applications, as they tolerate extremely harsh conditions. Detecting the existence of these microbes by a metabarcoding approach could be a primary step to harness their potential. Three salt pans viz. Agarwado, Curca, and Nerul adjoining prominent estuaries of Goa were selected based on their unique geographical locations. The sediments of these salt pans were examined for their bacterial community and function by 16S rRNA amplicon-sequencing. These salt pans were hypersaline (400-450 PSU) and alkaline (pH 7.6-8.25), with 0.036-0.081 mg/L nitrite, 0.0031-0.016 mg/L nitrate, 6.66-15.81 mg/L sulfate, and 20.8-25.6 mg/L sulfide. The relative abundance revealed that the Pseudomonadota was dominant in salt pans of Nerul (13.9%), Curca (19.6%), and Agarwado (32.4%). The predominant genera in Nerul, Curca, and Agarwado salt pan sediments were Rhodopirellula (1.12%), Sulfurivermis (1.28%), and Psychrobacter (25.5%) respectively. The highest alpha diversity (Shannon-diversity Index) was observed in the Nerul salt pan (4.8) followed by Curca (4.3) and Agarwado (2.03). Beta diversity indicated the highest dissimilarity between Agarwado and the other two salt pans (0.73) viz. Nerul and Curca and the lowest dissimilarity was observed between Nerul and Curca salt pans (0.48). Additionally, in the Agarwado salt pan, 125 unique genera were detected, while in Nerul 119, and in Curca 28 distinct genera were noted. The presence of these exclusive microorganisms in a specific salt pan and its absence in the others indicate that the adjacent estuaries play a critical role in determining salt pan bacterial diversity. Further, the functional prediction of bacterial communities indicated the predominance of stress adaptation genes involved in osmotic balance, membrane modification, and DNA repair mechanisms. This is the first study to report the bacterial community structure and its functional genes in these three salt pans using Next-Generation Sequencing. The data generated could be used as a reference by other researchers across the world for bioprospecting these organisms for novel compounds having biotechnological and biomedical potential.

Progress of Conjugated Linoleic Acid on Milk Fat Metabolism in Ruminants and Humans

As a valuable nutrient in milk, fat accounts for a significant proportion of the energy requirements of ruminants and is largely responsible for determining milk quality. Fatty acids (FAs) are a pivotal component of milk fat. Conjugated linoleic acid (CLA) is one of the naturally occurring FAs prevalent in ruminant dairy products and meat. Increasing attention has been given to CLA because of its anti-cancer, anti-inflammatory, immune regulation, and lipid metabolism regulation properties, and these benefits potentially contribute to the growth and health of infants. In breast milk, CLA is present in trace amounts, mainly in the form of cis-9, trans-11 CLA. Notably, cis-9, trans-11 CLA improves the milk fat rate while trans-10, cis-12 CLA inhibits it. Apart from having multiple physiological functions, CLA is also a pivotal factor in determining the milk quality of ruminants, especially milk fat rate. In response to growing interest in green and healthy functional foods, more and more researchers are exploring the potential of CLA to improve the production performance of animals and the nutritional value of livestock products. Taken together, it is novel and worthwhile to investigate how CLA regulates milk fat synthesis. It is the purpose of this review to clarify the necessity for studying CLA in ruminant milk fat and breast milk fat.

Functional transcriptome reveals hepatopancreatic lipid metabolism during the molting cycle of the Chinese mitten crab Eriocheir sinensis

Crustacean molting is highly related to energy and lipid metabolism. This study was conducted to detect the changes of total lipids (TL), triacylglyceride (TAG), phospholipid (PL) and lipid droplets in hepatopancreas, and then to investigate the gene expression patterns related to hepatopancreatic lipid metabolism during the molting cycle of Chinese mitten crab Eriocheir sinensis. Hepatopancreatic TL and TAG increased significantly from post-molt stage to pre-molt stage, then decreased significantly from pre-molt stage to ecdysis stage, which is consistent to the changes of neutral lipid-rich adipocytes in hepatopancreas. By transcriptomic analysis, 65,325 transcripts were sequenced and assembled, and 28,033 transcripts were annotated. Most genes were related to energy metabolism, and the enriched genes were involved in carbohydrate and lipid metabolism and biosynthesis, especially in de novo synthesis of fatty acids and TAG, and ketone body production. Compared to the inter-molt stages, acetyl-CoA carboxylase, fatty acid synthase and other genes related to the synthesis of fatty acids were upregulated in the pre-molt stage. TAG synthesis related genes, including Glycerol-3-phosphate acyltransferase and 1-acylglycerol-3-phosphate acyltransferases, were upregulated in the post-molt stage compared to the inter-molt stage. The expression of ketone body-related genes had no significant changes during the molting cycle. Compared to the TAG synthetic pathway, ketone body biosynthesis may contribute less/secondarily to fatty acid metabolic processes, which could be involved in the other physiological processes or metabolism. In conclusion, these results showed that TAG is the major lipid deposition during inter- and pre-molt stages, and the most genes are related to the fatty acids and TAG metabolism in the hepatopancreas during the molting cycle of E. sinensis.

Alcohol, White Adipose Tissue, and Brown Adipose Tissue: Mechanistic Links to Lipogenesis and Lipolysis

According to data from the World Health Organization, there were about 3 million deaths caused by alcohol consumption worldwide in 2016, of which about 50% were related to liver disease. Alcohol consumption interfering with the normal function of adipocytes has an important impact on the pathogenesis of alcoholic liver disease. There has been increasing recognition of the crucial role of adipose tissue in regulating systemic metabolism, far beyond that of an inert energy storage organ in recent years. The endocrine function of adipose tissue is widely recognized, and the significance of the proteins it produces and releases is still being investigated. Alcohol consumption may affect white adipose tissue (WAT) and brown adipose tissue (BAT), which interact with surrounding tissues such as the liver and intestines. This review briefly introduces the basic concept and classification of adipose tissue and summarizes the mechanism of alcohol affecting lipolysis and lipogenesis in WAT and BAT. The adipose tissue-liver axis is crucial in maintaining lipid homeostasis within the body. Therefore, this review also demonstrates the effects of alcohol consumption on the adipose tissue-liver axis to explore the role of alcohol consumption in the crosstalk between adipose tissue and the liver.

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.

Dysregulation of Lipid and Glucose Metabolism in Nonalcoholic Fatty Liver Disease

Non-Alcoholic Fatty Liver Disease (NAFLD) is a highly prevalent condition affecting approximately a quarter of the global population. It is associated with increased morbidity, mortality, economic burden, and healthcare costs. The disease is characterized by the accumulation of lipids in the liver, known as steatosis, which can progress to more severe stages such as steatohepatitis, fibrosis, cirrhosis, and even hepatocellular carcinoma (HCC). This review focuses on the mechanisms that contribute to the development of diet-induced steatosis in an insulin-resistant liver. Specifically, it discusses the existing literature on carbon flux through glycolysis, ketogenesis, TCA (Tricarboxylic Acid Cycle), and fatty acid synthesis pathways in NAFLD, as well as the altered canonical insulin signaling and genetic predispositions that lead to the accumulation of diet-induced hepatic fat. Finally, the review discusses the current therapeutic efforts that aim to ameliorate various pathologies associated with NAFLD.

Perturbation of arachidonic acid and glycerolipid metabolism promoted particulate matter-induced inflammatory responses in human bronchial epithelial cells

Particulate matter (PM) has become the main risk factor for public health, being linked with an increased risk of respiratory diseases. However, the potential mechanisms underlying PM-induced lung injury have not been well elucidated. In this study, we systematically integrated the metabolomics, lipidomics, and transcriptomics data obtained from the human bronchial epithelial cells (HBECs) exposed to PM to reveal metabolic disorders in PM-induced lung injury. We identified 170 differentially expressed metabolites (82 upregulated and 88 downregulated metabolites), 218 differentially expressed lipid metabolites (125 upregulated and 93 downregulated lipid metabolites), and 1417 differentially expressed genes (643 upregulated and 774 downregulated genes). Seven key metabolites (prostaglandin E2, inosinic acid, L-arginine, L-citrulline, L-leucine, adenosine, and adenosine monophosphate), and two main lipid subclasses (triglyceride and phosphatidylcholine) were identified in PM-exposed HBECs. The amino acid metabolism, lipid metabolism, and carbohydrate metabolism were the significantly enriched pathways of identified differentially expressed genes. Then, conjoint analysis of these three omics data and further qRT-PCR validation showed that arachidonic acid metabolism, glycerolipid metabolism, and glutathione metabolism were the key metabolic pathways in PM-exposed HBECs. The knockout of AKR1C3 in arachidonic acid metabolism or GPAT3 in glycerolipid metabolism could significantly inhibit PM-induced inflammatory responses in HBECs. These results revealed the potential metabolic pathways in PM-exposed HBECs and provided a new target to protect from PM-induced airway damage.

In Silico Analysis of Changes in Predicted Metabolic Capabilities of Intestinal Microbiota after Fecal Microbial Transplantation for Treatment of Recurrent Clostridioides difficile Infection

IMPORTANCE

Although highly effective in treating recurrent Clostridioides difficile infection (RCDI), the mechanisms of action of fecal microbial transplantation (FMT) are not fully understood.

AIM

The aim of this study was to explore microbially derived products or pathways that could contribute to the therapeutic efficacy of FMT.

METHODS

Stool shotgun metagenomic sequencing data from 18 FMT-treated RCDI patients at 4 points in time were used for the taxonomic and functional profiling of their gut microbiome. The abundance of the KEGG orthology (KO) groups was subjected to univariate linear mixed models to assess the significance of the observed differences between 0 (pre-FMT), 1, 4, and 12 weeks after FMT.

RESULTS

Of the 59,987 KO groups identified by shotgun metagenomic sequencing, 27 demonstrated a statistically significant change after FMT. These KO groups are involved in many cellular processes, including iron homeostasis, glycerol metabolism, and arginine regulation, all of which have been implicated to play important roles in bacterial growth and virulence in addition to modulating the intestinal microbial composition.

CONCLUSION

Our findings suggest potential changes in key KO groups post-FMT, which may contribute to FMT efficacy beyond the restored microbial composition/diversity and metabolism of bile acids and short-chain fatty acids. Future larger studies that include a fecal metabolomics analysis combined with animal model validation work are required to further elucidate the molecular mechanisms.

The Effect of Bioactive Aliment Compounds and Micronutrients on Non-Alcoholic Fatty Liver Disease

In the current review, we focused on identifying aliment compounds and micronutrients, as well as addressed promising bioactive nutrients that may interfere with NAFLD advance and ultimately affect this disease progress. In this regard, we targeted: 1. Potential bioactive nutrients that may interfere with NAFLD, specifically dark chocolate, cocoa butter, and peanut butter which may be involved in decreasing cholesterol concentrations. 2. The role of sweeteners used in coffee and other frequent beverages; in this sense, stevia has proven to be adequate for improving carbohydrate metabolism, liver steatosis, and liver fibrosis. 3. Additional compounds were shown to exert a beneficial action on NAFLD, namely glutathione, soy lecithin, silymarin, Aquamin, and cannabinoids which were shown to lower the serum concentration of triglycerides. 4. The effects of micronutrients, especially vitamins, on NAFLD. Even if most studies demonstrate the beneficial role of vitamins in this pathology, there are exceptions. 5. We provide information regarding the modulation of the activity of some enzymes related to NAFLD and their effect on this disease. We conclude that NAFLD can be prevented or improved by different factors through their involvement in the signaling, genetic, and biochemical pathways that underlie NAFLD. Therefore, exposing this vast knowledge to the public is particularly important.

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.

Non-Synonymous Variants in Fat QTL Genes among High- and Low-Milk-Yielding Indigenous Breeds

The effect of breed on milk components-fat, protein, lactose, and water-has been observed to be significant. As fat is one of the major price-determining factors for milk, exploring the variations in fat QTLs across breeds would shed light on the variable fat content in their milk. Here, on whole-genome sequencing, 25 differentially expressed hub or bottleneck fat QTLs were explored for variations across indigenous breeds. Out of these, 20 genes were identified as having nonsynonymous substitutions. A fixed SNP pattern in high-milk-yielding breeds in comparison to low-milk-yielding breeds was identified in the genes GHR, TLR4, LPIN1, CACNA1C, ZBTB16, ITGA1, ANK1, and NTG5E and, vice versa, in the genes MFGE8, FGF2, TLR4, LPIN1, NUP98, PTK2, ZTB16, DDIT3, and NT5E. The identified SNPs were ratified by pyrosequencing to prove that key differences exist in fat QTLs between the high- and low-milk-yielding breeds.

(Pro)Renin Receptor Antagonism Attenuates High-Fat-Diet-Induced Hepatic Steatosis

Non-alcoholic fatty liver disease (NAFLD) comprises a spectrum of liver damage directly related to diabetes, obesity, and metabolic syndrome. The (pro)renin receptor (PRR) has recently been demonstrated to play a role in glucose and lipid metabolism. Here, we test the hypothesis that the PRR regulates the development of diet-induced hepatic steatosis and fibrosis. C57Bl/6J mice were fed a high-fat diet (HFD) or normal-fat diet (NFD) with matching calories for 6 weeks. An 8-week methionine choline-deficient (MCD) diet was used to induce fibrosis. Two weeks following diet treatment, mice were implanted with a subcutaneous osmotic pump delivering either the peptide PRR antagonist, PRO20, or scrambled peptide for 4 or 6 weeks. Mice fed a 6-week HFD exhibited increased liver lipid accumulation and liver triglyceride content compared with NFD-fed mice. Importantly, PRO20 treatment reduced hepatic lipid accumulation in HFD-fed mice without affecting body weight or blood glucose. Furthermore, PRR antagonism attenuated HFD-induced steatosis, particularly microvesicular steatosis. In the MCD diet model, the percentage of collagen area was reduced in PRO20-treated compared with control mice. PRO20 treatment also significantly decreased levels of liver alanine aminotransferase, an indicator of liver damage, in MCD-fed mice compared with controls. Mechanistically, we found that PRR antagonism prevented HFD-induced increases in PPARγ and glycerol-3-phosphate acyltransferase 3 expression in the liver. Taken together, our findings establish the involvement of the PRR in liver triglyceride synthesis and suggest the therapeutic potential of PRR antagonism for the treatment of liver steatosis and fibrosis in NAFLD.

Improved lipogenesis gene expression in liver is associated with elevated plasma angiotensin 1-7 after AT1 receptor blockade in insulin-resistant OLETF rats

Increased angiotensin II (Ang II) signaling contributes to insulin resistance and liver steatosis. In addition to ameliorating hypertension, angiotensin receptor blockers (ARBs) improve lipid metabolism and hepatic steatosis, which are impaired with metabolic syndrome (MetS). Chronic blockade of the Ang II receptor type 1 (AT1) increases plasma angiotensin 1-7 (Ang 1-7), which mediates mechanisms counterregulatory to AT1 signaling. Elevated plasma Ang 1-7 is associated with decreased plasma triacylglycerol (TAG), cholesterol, glucose, and insulin; however, the benefits of RAS modulation to prevent non-alcoholic fatty liver disease (NAFLD) are not fully investigated. To better address the relationships among chronic ARB treatment, plasma Ang 1-7, and hepatic steatosis, three groups of 10-week-old-rats were studied: (1) untreated lean Long Evans Tokushima Otsuka (LETO), (2) untreated Otsuka Long Evans Tokushima Fatty (OLETF), and (3) OLETF + ARB (ARB; 10 mg olmesartan/kg/d × 6 weeks). Following overnight fasting, rats underwent an acute glucose load to better understand the dynamic metabolic responses during hepatic steatosis and early MetS. Tissues were collected at baseline (pre-load; T0) and 1 and 2 h post-glucose load. AT1 blockade increased plasma Ang 1-7 and decreased liver lipids, which was associated with decreased fatty acid transporter 5 (FATP5) and fatty acid synthase (FASN) expression. AT1 blockade decreased liver glucose and increased glucokinase (GCK) expression. These results demonstrate that during MetS, overactivation of AT1 promotes hepatic lipid deposition that is stimulated by an acute glucose load and lipogenesis genes, suggesting that the chronic hyperglycemia associated with MetS contributes to fatty liver pathologies via an AT1-mediated mechanism.

Rapamycin/metformin co-treatment normalizes insulin sensitivity and reduces complications of metabolic syndrome in type 2 diabetic mice

Rapamycin treatment has positive and negative effects on progression of type 2 diabetes (T2D) in a recombinant inbred polygenic mouse model, male NONcNZO10/LtJ (NcZ10). Here, we show that combination treatment with metformin ameliorates negative effects of rapamycin while maintaining its benefits. From 12 to 30 weeks of age, NcZ10 males were fed a control diet or diets supplemented with rapamycin, metformin, or a combination of both. Rapamycin alone reduced weight gain, adiposity, HOMA-IR, and inflammation, and prevented hyperinsulinemia and pre-steatotic hepatic lipidosis, but exacerbated hyperglycemia, hypertriglyceridemia, and pancreatic islet degranulation. Metformin alone reduced hyperinsulinemia and circulating c-reactive protein, but exacerbated nephropathy. Combination treatment retained the benefits of both while preventing many of the deleterious effects. Importantly, the combination treatment reversed effects of rapamycin on markers of hepatic insulin resistance and normalized systemic insulin sensitivity in this inherently insulin-resistant model. In adipose tissue, rapamycin attenuated the expression of genes associated with adipose tissue expansion (Mest, Gpam), inflammation (Itgam, Itgax, Hmox1, Lbp), and cell senescence (Serpine1). In liver, the addition of metformin counteracted rapamycin-induced alterations of G6pc, Ppara, and Ldlr expressions that promote hyperglycemia and hypertriglyceridemia. Both rapamycin and metformin treatment reduced hepatic Fasn expression, potentially preventing lipidosis. These results delineate a state of "insulin signaling restriction" that withdraws endocrine support for further adipogenesis, progression of the metabolic syndrome, and the development of its comorbidities. Our results are relevant for the treatment of T2D, the optimization of current rapamycin-based treatments for posttransplant rejection and various cancers, and for the development of treatments for healthy aging.

Lipid balance remodelling by human positive-strand RNA viruses and the contribution of lysosomes

A marked reorganization of internal membranes occurs in the cytoplasm of cells infected by single stranded positive-sense RNA viruses. Most cell compartments change their asset to provide lipids for membrane rearrangement into replication organelles, where to concentrate viral proteins and enzymes while hiding from pathogen pattern recognition molecules. Because the endoplasmic reticulum is a central hub for lipid metabolism, when viruses hijack the organelle to form their replication organelles, a cascade of events change the intracellular environment. This results in a marked increase in lipid consumption, both by lipolysis and lipophagy of lipid droplets. In addition, lipids are used to produce energy for viral replication. At the same time, inflammation is started by signalling lipids, where lysosomal processing plays a relevant role. This review is aimed at providing an overview on what takes place after human class IV viruses have released their genome into the host cell and the consequences on lipid metabolism, including lysosomes.

Native chemical ligation approach to sensitively probe tissue acyl-CoA pools

During metabolism, carboxylic acids are often activated by conjugation to the thiol of coenzyme A (CoA). The resulting acyl-CoAs comprise a group of ∼100 thioester-containing metabolites that could modify protein behavior through non-enzymatic N-acylation of lysine residues. However, the importance of many potential acyl modifications remains unclear because antibody-based methods to detect them are unavailable and the in vivo concentrations of their respective acyl-CoAs are poorly characterized. Here, we develop cysteine-triphenylphosphonium (CysTPP), a mass spectrometry probe that uses "native chemical ligation" to sensitively detect the major acyl-CoAs present in vivo through irreversible modification of its amine via a thioester intermediate. Using CysTPP, we show that longer-chain (C13-C22) acyl-CoAs often constitute ∼60% of the acyl-CoA pool in rat tissues. These hydrophobic longer-chain fatty acyl-CoAs have the potential to non-enzymatically modify protein residues.

Identifying Candidate Flavonoids for Non-Alcoholic Fatty Liver Disease by Network-Based Strategy

Nonalcoholic fatty liver disease (NAFLD) is the most common type of chronic liver disease and lacks guaranteed pharmacological therapeutic options. In this study, we applied a network-based framework for comprehensively identifying candidate flavonoids for the prevention and/or treatment of NAFLD. Flavonoid-target interaction information was obtained from combining experimentally validated data and results obtained using a recently developed machine-learning model, AI-DTI. Flavonoids were then prioritized by calculating the network proximity between flavonoid targets and NAFLD-associated proteins. The preventive effects of the candidate flavonoids were evaluated using FFA-induced hepatic steatosis in HepG2 and AML12 cells. We reconstructed the flavonoid-target network and found that the number of re-covered compound-target interactions was significantly higher than the chance level. Proximity scores have successfully rediscovered flavonoids and their potential mechanisms that are reported to have therapeutic effects on NAFLD. Finally, we revealed that discovered candidates, particularly glycitin, significantly attenuated lipid accumulation and moderately inhibited intracellular reactive oxygen species production. We further confirmed the affinity of glycitin with the predicted target using molecular docking and found that glycitin targets are closely related to several proteins involved in lipid metabolism, inflammatory responses, and oxidative stress. The predicted network-level effects were validated at the levels of mRNA. In summary, our study offers and validates network-based methods for the identification of candidate flavonoids for NAFLD.

Chronic angiotensin receptor activation promotes hepatic triacylglycerol accumulation during an acute glucose challenge in obese-insulin-resistant OLETF rats

PURPOSE

Angiotensin receptor blockers (ARBs) can ameliorate metabolic syndrome (MetS)-associated dyslipidemia, hepatic steatosis, and glucose intolerance, suggesting that angiotensin receptor (AT1) over-activation contributes to impaired lipid and glucose metabolism, which is characteristic of MetS. The aim of this study was to evaluate changes in the lipid profile and proteins of fatty acid uptake, triacylglycerol (TAG) synthesis, and β-oxidation to better understand the links between AT1 overactivation and non-alcoholic fatty liver disease (NAFLD) during MetS.

METHODS

Four groups of 25-week-old-rats were used: (1) untreated LETO, (2) untreated OLETF, (3) OLETF + angiotensin receptor blocker (ARB; 10 mg olmesartan/kg/d × 8 weeks) and (4) OLETF ± ARB (MINUS; 10 mg olmesartan/kg/d × 4 weeks, then removed until dissection). To investigate the dynamic shifts in metabolism, animals were dissected after an oral glucose challenge (fasting, 3 and 6 h post-glucose).

RESULTS

Compared to OLETF, plasma total cholesterol and TAG remained unchanged in ARB. However, liver TAG was 55% lesser in ARB than OLETF, and remained lower throughout the challenge. Basal CD36 and ApoB were 28% and 29% lesser, respectively, in ARB than OLETF. PRDX6 abundance in ARB was 45% lesser than OLETF, and it negatively correlated with liver TAG in ARB.

CONCLUSIONS

Chronic blockade of AT1 protects the liver from TAG accumulation during glucose overload. This may be achieved by modulating NEFA uptake and increasing TAG export via ApoB. Our study highlights the contributions of AT1 signaling to impaired hepatic substrate metabolism and the detriments of a high-glucose load and its potential contribution to steatosis during MetS.

Cynanchum atratum Alleviates Non-Alcoholic Fatty Liver by Balancing Lipogenesis and Fatty Acid Oxidation in a High-Fat, High-Fructose Diet Mice Model

Cynanchum atratum, a medicinal herb, is traditionally used as an antidote, diuretic, and antipyretic in eastern Asia. The current study aimed to investigate the anti-fatty liver capacity of the ethanol extract of Cynanchum atratum (CAE) using a 10-week high-fat, high-fructose diet mouse model. A six-week treatment of CAE (from the fifth week) significantly attenuated the weights of the body, liver, and mesenteric fat without a change in diet intake. CAE also considerably restored the alterations of serum aminotransferases and free fatty acid, fasting blood glucose, serum and hepatic triglyceride, and total cholesterol, as well as platelet and leukocyte counts. Meanwhile, CAE ameliorated hepatic injury and lipid accumulation, as evidenced by histopathological and immunofluorescence observations. Additionally, CAE significantly lowered the elevation of hepatic TNF-α, the TNF-α/IL-10 ratio, fecal endotoxins, and the abundance of Gram-negative bacteria. Hepatic lipogenesis and β-oxidation-related proteins and gene expression, including PPAR-α, SREBP-1, SIRT1, FAS, CTP1, etc., were normalized markedly by CAE. In particular, the AMPK, a central regulator of energy metabolism, was phosphorylated by CAE at an even higher rate than metformin. Overall, CAE exerts anti-hepatic steatosis effects by reducing lipogenesis and enhancing fatty acid oxidation. Consequently, Cynanchum atratum is expected to be a promising candidate for treating chronic metabolic diseases.

Impacts of Embryonic Thermal Programming on the Expression of Genes Involved in Foie gras Production in Mule Ducks

Embryonic thermal programming has been shown to improve foie gras production in overfed mule ducks. However, the mechanisms at the origin of this programming have not yet been characterized. In this study, we investigated the effect of embryonic thermal manipulation (+1°C, 16 h/24 h from embryonic (E) day 13 to E27) on the hepatic expression of genes involved in lipid and carbohydrate metabolisms, stress, cell proliferation and thyroid hormone pathways at the end of thermal manipulation and before and after overfeeding (OF) in mule ducks. Gene expression analyses were performed by classic or high throughput real-time qPCR. First, we confirmed well-known results with strong impact of OF on the expression of genes involved in lipid and carbohydrates metabolisms. Then we observed an impact of OF on the hepatic expression of genes involved in the thyroid pathway, stress and cell proliferation. Only a small number of genes showed modulation of expression related to thermal programming at the time of OF, and only one was also impacted at the end of the thermal manipulation. For the first time, we explored the molecular mechanisms of embryonic thermal programming from the end of heat treatment to the programmed adult phenotype with optimized liver metabolism.

Heart failure in diabetes

Heart failure and cardiovascular disorders represent the leading cause of death in diabetic patients. Here we present a systematic review of the main mechanisms underlying the development of diabetic cardiomyopathy. We also provide an excursus on the relative contribution of cardiomyocytes, fibroblasts, endothelial and smooth muscle cells to the pathophysiology of heart failure in diabetes. After having described the preclinical tools currently available to dissect the mechanisms of this complex disease, we conclude with a section on the most recent updates of the literature on clinical management.

Roles of IκB kinases and TANK-binding kinase 1 in hepatic lipid metabolism and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and is strongly associated with obesity-related ectopic fat accumulation in the liver. Hepatic lipid accumulation encompasses a histological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), which can progress to cirrhosis and hepatocellular carcinoma. Given that dysregulated hepatic lipid metabolism may be an onset factor in NAFLD, understanding how hepatic lipid metabolism is modulated in healthy subjects and which steps are dysregulated in NAFLD subjects is crucial to identify effective therapeutic targets. Additionally, hepatic inflammation is involved in chronic hepatocyte damage during NAFLD progression. As a key immune signaling hub that mediates NF-κB activation, the IκB kinase (IKK) complex, including IKKα, IKKβ, and IKKγ (NEMO), has been studied as a crucial regulator of the hepatic inflammatory response and hepatocyte survival. Notably, TANK-binding kinase 1 (TBK1), an IKK-related kinase, has recently been revealed as a potential link between hepatic inflammation and energy metabolism. Here, we review (1) the biochemical steps of hepatic lipid metabolism; (2) dysregulated lipid metabolism in obesity and NAFLD; and (3) the roles of IKKs and TBK1 in obesity and NAFLD.

Genetic engineering of microalgae for enhanced lipid production

Microalgae have the potential to become microbial cell factories for lipid production. Their ability to convert sunlight and CO₂ into valuable lipid compounds has attracted interest from cosmetic, biofuel, food and feed industries. In order to make microalgae-derived products cost-effective and commercially competitive, enhanced growth rates and lipid productivities are needed, which require optimization of cultivation systems and strain improvement. Advances in genetic tool development and omics technologies have increased our understanding of lipid metabolism, which has opened up possibilities for targeted metabolic engineering. In this review we provide a comprehensive overview on the developments made to genetically engineer microalgal strains over the last 30 years. We focus on the strategies that lead to an increased lipid content and altered fatty acid profile. These include the genetic engineering of the fatty acid synthesis pathway, Kennedy pathway, polyunsaturated fatty acid and triacylglycerol metabolisms and fatty acid catabolism. Moreover, genetic engineering of specific transcription factors, NADPH generation and central carbon metabolism, which lead to increase of lipid accumulation are also reviewed.

The modified mitochondrial outer membrane carrier MTCH2 links mitochondrial fusion to lipogenesis

Mitochondrial function is integrated with cellular status through the regulation of opposing mitochondrial fusion and division events. Here we uncover a link between mitochondrial dynamics and lipid metabolism by examining the cellular role of mitochondrial carrier homologue 2 (MTCH2). MTCH2 is a modified outer mitochondrial membrane carrier protein implicated in intrinsic cell death and in the in vivo regulation of fatty acid metabolism. Our data indicate that MTCH2 is a selective effector of starvation-induced mitochondrial hyperfusion, a cytoprotective response to nutrient deprivation. We find that MTCH2 stimulates mitochondrial fusion in a manner dependent on the bioactive lipogenesis intermediate lysophosphatidic acid. We propose that MTCH2 monitors flux through the lipogenesis pathway and transmits this information to the mitochondrial fusion machinery to promote mitochondrial elongation, enhanced energy production, and cellular survival under homeostatic and starvation conditions. These findings will help resolve the roles of MTCH2 and mitochondria in tissue-specific lipid metabolism in animals.

Orally administered nano-polystyrene caused vitellogenin alteration and oxidative stress in the red swamp crayfish (Procambarus clarkii)

Nanoplastics (≤100 nm) represent the smallest fraction of plastic litter and may result in the aquatic environment as degradation products of larger plastic material. To date, few studies focused on the interactions of micro- and nanoplastics with freshwater Decapoda. The red swamp crayfish (Procambarus clarkii, Girard, 1852) is an invasive species able to tolerate highly perturbed environments. As a benthic opportunistic feeder, this species may be susceptible to plastic ingestion. In this study, adult P. clarkii, at intermolt stage, were exposed to 100 μg of 100 nm carboxylated polystyrene nanoparticles (PS NPs) through diet in a 72 h acute toxicity test. An integrated approach was conceived to assess the biological effects of PS NPs, by analyzing both transcriptomic and physiological responses. Total hemocyte counts, basal and total phenoloxidase activities, glycemia and total protein concentration were investigated in crayfish hemolymph at 0 h, 24 h, 48 h and 72 h from PS NPs administration to evaluate general stress response over time. Differentially expressed genes (DEGs) in the hemocytes and hepatopancreas were analyzed to ascertain the response of crayfish to PS NP challenge after 72 h. At a physiological level, crayfish were able to compensate for the induced stress, not exceeding generic stress thresholds. The RNA-Sequencing analysis revealed the altered expression of few genes involved in immune response, oxidative stress, gene transcription and translation, protein degradation, lipid metabolism, oxygen demand, and reproduction after PS NPs exposure. This study suggests that a low concentration of PS NPs may induce mild stress in crayfish, and sheds light on molecular pathways possibly involved in nanoplastic toxicity.

Genome-wide analyses of multiple obesity-related cytokines and hormones informs biology of cardiometabolic traits

BACKGROUND

A complex set of perturbations occur in cytokines and hormones in the etiopathogenesis of obesity and related cardiometabolic conditions such as type 2 diabetes (T2D). Evidence for the genetic regulation of these cytokines and hormones is limited, particularly in African-ancestry populations. In order to improve our understanding of the biology of cardiometabolic traits, we investigated the genetic architecture of a large panel of obesity- related cytokines and hormones among Africans with replication analyses in African Americans.

METHODS

We performed genome-wide association studies (GWAS) in 4432 continental Africans, enrolled from Ghana, Kenya, and Nigeria as part of the Africa America Diabetes Mellitus (AADM) study, for 13 obesity-related cytokines and hormones, including adipsin, glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1), interleukin-1 receptor antagonist (IL1-RA), interleukin-6 (IL-6), interleukin-10 (IL-10), leptin, plasminogen activator inhibitor-1 (PAI-1), resistin, visfatin, insulin, glucagon, and ghrelin. Exact and local replication analyses were conducted in African Americans (n = 7990). The effects of sex, body mass index (BMI), and T2D on results were investigated through stratified analyses.

RESULTS

GWAS identified 39 significant (P value < 5 × 10-8) loci across all 13 traits. Notably, 14 loci were African-ancestry specific. In this first GWAS for adipsin and ghrelin, we detected 13 and 4 genome-wide significant loci respectively. Stratified analyses by sex, BMI, and T2D showed a strong effect of these variables on detected loci. Eight novel loci were successfully replicated: adipsin (3), GIP (1), GLP-1 (1), and insulin (3). Annotation of these loci revealed promising links between these adipocytokines and cardiometabolic outcomes as illustrated by rs201751833 for adipsin and blood pressure and locus rs759790 for insulin level and T2D in lean individuals.

CONCLUSIONS

Our study identified genetic variants underlying variation in multiple adipocytokines, including the first loci for adipsin and ghrelin. We identified population differences in variants associated with adipocytokines and highlight the importance of stratification for discovery of loci. The high number of African-specific loci detected emphasizes the need for GWAS in African-ancestry populations, as these loci could not have been detected in other populations. Overall, our work contributes to the understanding of the biology linking adipocytokines to cardiometabolic traits.

Glycerol-3-phosphate biosynthesis regenerates cytosolic NAD+ to alleviate mitochondrial disease

Electron transport chain (ETC) dysfunction or hypoxia causes toxic NADH accumulation. How cells regenerate NAD⁺ under such conditions remains elusive. Here, integrating bioinformatic analysis and experimental validation, we identify glycerol-3-phosphate (Gro3P) biosynthesis as an endogenous NAD⁺-regeneration pathway. Under genetic or pharmacological ETC inhibition, disrupting Gro3P synthesis inhibits yeast proliferation, shortens lifespan of C. elegans, impairs growth of cancer cells in culture and in xenografts, and causes metabolic derangements in mouse liver. Moreover, the Gro3P shuttle selectively regenerates cytosolic NAD⁺ under mitochondrial complex I inhibition; enhancing Gro3P synthesis promotes shuttle activity to restore proliferation of complex I-impaired cells. Mouse brain has much lower levels of Gro3P synthesis enzymes as compared with other organs. Strikingly, enhancing Gro3P synthesis suppresses neuroinflammation and extends lifespan in the Ndufs4^-/- mice. Collectively, our results reveal Gro3P biosynthesis as an evolutionarily conserved coordinator of NADH/NAD⁺ redox homeostasis and present a therapeutic target for mitochondrial complex I diseases.

The Role of Dietary and Microbial Fatty Acids in the Control of Inflammation in Neonatal Piglets

Simple Summary

The maturation of the gut is a specific and very dynamic process in new-born piglets. Consequently, piglet’s gut is very susceptible to disturbances, especially in stressful periods of life, such as weaning, when the gut lining often becomes inflamed and leaky. Dietary fatty acids (FA) do not only serve as source of energy and essential FA, but they are important precursors for bioactive lipid mediators, which modulate inflammatory signalling in the body. The current review summarizes results on dietary sources of FA for piglets, the signalling cascades, bioactivities, the necessity to consider the autoxidation potential of polyunsaturated FA and the area of microbially produced long-chain FA. That said, porcine milk is high in fat, whereby the milk FA composition partly depends on the dietary FA composition of the sow. Therefore, manipulation of the sow diet is an efficient tool to increase the piglet’s intake of specific FA, e.g., n-3 polyunsaturated FA which show anti-inflammatory activity and may support intestinal integrity and functioning in the growing animal.

Abstract

Excessive inflammation and a reduced gut mucosal barrier are major causes for gut dysfunction in piglets. The fatty acid (FA) composition of the membrane lipids is crucial for mediating inflammatory signalling and is largely determined by their dietary intake. Porcine colostrum and milk are the major sources of fat in neonatal piglets. Both are rich in fat, demonstrating the dependence of the young metabolism from fat and providing the young organism with the optimum profile of lipids for growth and development. The manipulation of sow’s dietary polyunsaturated FA (PUFA) intake has been shown to be an efficient strategy to increase the transfer of specific FAs to the piglet for incorporation in enteric tissues and cell membranes. n-3 PUFAs, especially seems to be beneficial for the immune response and gut epithelial barrier function, supporting the piglet’s enteric defences in situations of increased stress such as weaning. Little is known about microbial lipid mediators and their role in gut barrier function and inhibition of inflammation in neonatal piglets. The present review summarizes the current knowledge of lipid nutrition in new-born piglets, comparing the FA ingestion from milk and plant-based lipid sources and touching the areas of host lipid signalling, inflammatory signalling and microbially derived FAs.

A20 deficiency in myeloid cells protects mice from diet-induced obesity and insulin resistance due to increased fatty acid metabolism

Obesity-induced inflammation is a major driving force in the development of insulin resistance, type 2 diabetes (T2D), and related metabolic disorders. During obesity, macrophages accumulate in the visceral adipose tissue, creating a low-grade inflammatory environment. Nuclear factor κB (NF-κB) signaling is a central coordinator of inflammatory responses and is tightly regulated by the anti-inflammatory protein A20. Here, we find that myeloid-specific A20-deficient mice are protected from diet-induced obesity and insulin resistance despite an inflammatory environment in their metabolic tissues. Macrophages lacking A20 show impaired mitochondrial respiratory function and metabolize more palmitate both in vitro and in vivo. We hypothesize that A20-deficient macrophages rely more on palmitate oxidation and metabolize the fat present in the diet, resulting in a lean phenotype and protection from metabolic disease. These findings reveal a role for A20 in regulating macrophage immunometabolism.