Transcriptional, post-transcriptional, and post-translational regulation of polyunsaturated fatty acid synthase genes in Aurantiochytrium limacinum strain BL10: Responses to nitrogen starvation.

Under nitrogen deficient conditions, the Aurantiochytrium limacinum strain BL10 greatly increases the production of docosahexaenoic acid (DHA) and n-6 docosapentaenoic acid. Researchers have yet to elucidate the mechanism by which BL10 promotes the activity of polyunsaturated fatty acid synthase (Pfa), which plays a key role in the synthesis of polyunsaturated fatty acid (PUFA). Analysis in the current study revealed that in nitrogen-depleted environments, BL10 boosts the transcription and synthesis of proteins by facilitating the expression of pfa genes via transcriptional regulation. It was also determined that BL10 adjusts the lengths of the 5'- and 3'-untranslated regions (suggesting post-transcriptional regulation) and modifies the ratio of two Pfa1 isoforms to favor PUFA production via post-translational regulation (ubiquitination). These findings clarify the exceptional DHA production of BL10 and provide additional insights into the regulatory mechanisms of PUFA biosynthesis in Aurantiochytrium.

A Characterization and Functional Analysis of Peroxisome Proliferator-Activated Receptor Gamma Splicing Variants in the Buffalo Mammary Gland.

Peroxisome proliferator-activated receptor γ (PPARG) has various splicing variants and plays essential roles in the regulation of adipocyte differentiation and lipogenesis. However, little is known about the expression pattern and effect of the PPARG on milk fat synthesis in the buffalo mammary gland. In this study, we found that only PPARG-X17 and PPARG-X21 of the splicing variant were expressed in the buffalo mammary gland. Amino acid sequence characterization showed that the proteins encoded by PPARG-X17 and PPARG-X21 are endonuclear non-secreted hydrophilic proteins. Protein domain prediction found that only the PPARG-X21-encoded protein had PPAR ligand-binding domains (NR_LBD_PPAR), which may lead to functional differences between the two splices. RNA interference (RNAi) and the overexpression of PPARG-X17 and PPARG-X21 in buffalo mammary epithelial cells (BMECs) were performed. Results showed that the expression of fatty acid synthesis-related genes (ACACA, CD36, ACSL1, GPAT, AGPAT6, DGAT1) was significantly modified (p < 0.05) by the RNAi and overexpression of PPARG-X17 and PPARG-X21. All kinds of FAs detected in this study were significantly decreased (p < 0.05) after RNAi of PPARG-X17 or PPARG-X21. Overexpression of PPARG-X17 or PPARG-X21 significantly decreased (p < 0.05) the SFA content, while significantly increased (p < 0.05) the UFA, especially the MUFA in the BMECs. In conclusion, there are two PPARG splicing variants expressed in the BMECs that can regulate FA synthesis by altering the expression of diverse fatty acid synthesis-related genes. This study revealed the expression characteristics and functions of the PPARG gene in buffalo mammary glands and provided a reference for further understanding of fat synthesis in buffalo milk.

Creating yellow seed Camelina sativa with enhanced oil accumulation by CRISPR-mediated disruption of Transparent Testa 8.

Camelina (Camelina sativa L.), a hexaploid member of the Brassicaceae family, is an emerging oilseed crop being developed to meet the increasing demand for plant oils as biofuel feedstocks. In other Brassicas, high oil content can be associated with a yellow seed phenotype, which is unknown for camelina. We sought to create yellow seed camelina using CRISPR/Cas9 technology to disrupt its Transparent Testa 8 (TT8) transcription factor genes and to evaluate the resulting seed phenotype. We identified three TT8 genes, one in each of the three camelina subgenomes, and obtained independent CsTT8 lines containing frameshift edits. Disruption of TT8 caused seed coat colour to change from brown to yellow reflecting their reduced flavonoid accumulation of up to 44%, and the loss of a well-organized seed coat mucilage layer. Transcriptomic analysis of CsTT8-edited seeds revealed significantly increased expression of the lipid-related transcription factors LEC1, LEC2, FUS3, and WRI1 and their downstream fatty acid synthesis-related targets. These changes caused metabolic remodelling with increased fatty acid synthesis rates and corresponding increases in total fatty acid (TFA) accumulation from 32.4% to as high as 38.0% of seed weight, and TAG yield by more than 21% without significant changes in starch or protein levels compared to parental line. These data highlight the effectiveness of CRISPR in creating novel enhanced-oil germplasm in camelina. The resulting lines may directly contribute to future net-zero carbon energy production or be combined with other traits to produce desired lipid-derived bioproducts at high yields.

A pyruvate transporter in the apicoplast of apicomplexan parasites.

Pyruvate lies at a pivotal node of carbon metabolism in eukaryotes. It is involved in diverse metabolic pathways in multiple organelles, and its interorganelle shuttling is crucial for cell fitness. Many apicomplexan parasites harbor a unique organelle called the apicoplast that houses metabolic pathways like fatty acid and isoprenoid precursor biosyntheses, requiring pyruvate as a substrate. However, how pyruvate is supplied in the apicoplast remains enigmatic. Here, deploying the zoonotic parasite Toxoplasma gondii as a model apicomplexan, we identified two proteins residing in the apicoplast membranes that together constitute a functional apicoplast pyruvate carrier (APC) to mediate the import of cytosolic pyruvate. Depletion of APC results in reduced activities of metabolic pathways in the apicoplast and impaired integrity of this organelle, leading to parasite growth arrest. APC is a pyruvate transporter in diverse apicomplexan parasites, suggesting a common strategy for pyruvate acquisition by the apicoplast in these clinically relevant intracellular pathogens.

Exploration of dietary interventions to treat mitochondrial fatty acid disorders in a mouse model.

Mitochondrial fatty acids synthesis (mtFAS) is a conserved metabolic pathway essential for mitochondrial respiration. The best characterized mtFAS product is the medium-chain fatty acid octanoate (C8) used as a substrate in the synthesis of lipoic acid (LA), a cofactor required by several mitochondrial enzyme complexes. In humans, mutations in the mtFAS component enoyl reductase MECR cause childhood-onset neurodegenerative disorder MEPAN. A complete deletion of Mecr in mice is embryonically lethal, while selective deletion of Mecr in cerebellar Purkinje cells causes neurodegeneration in these cells. A fundamental question in the research of mtFAS deficiency is if the defect is amenable to treatment by supplementation with known mtFAS products. Here we used the Purkinje-cell specific mtFAS deficiency neurodegeneration model mice to study if feeding the mice with a medium-chain triacylglycerol-rich formula supplemented with LA could slow down or prevent the neurodegeneration in Purkinje cell-specific Mecr KO mice. Feeding started at the age of 4 weeks and continued until the age of 9 months. The neurological status on the mice was assessed at the age of 3, 6, and 9 months with behavioral tests and the state of the Purkinje cell deterioration in the cerebellum was studied histologically. We showed that feeding the mice with medium chain triacylglycerols and LA affected fatty acid profiles in the cerebellum and plasma but did not prevent the development of neurodegeneration in these mice. Our results indicate that dietary supplementation with medium chain fatty acids and LA alone is not an efficient way to treat mtFAS disorders.

Aryl Hydrocarbon Receptor Activation Limits the Fatty Acid Synthesis and Subsequent "miR-193a-3p-HDAC3-FASN" Signals to Alleviate Intestinal Fibrosis.

Intestinal fibrosis is a common complication of Crohn's disease and characterized by excessive extracellular matrix (ECM) deposition. The aryl hydrocarbon receptor (AhR) detects micronutrients and microbial metabolites in diet and can attenuate intestinal fibrosis with unclear mechanisms. In this study, AhR activation was demonstrated to downregulate the transcription of collagen I and fibronectin in a Sp1- but not Sp3- or AP-1-dependent manner. A suppressed fatty acid synthesis was highlighted using untargeted metabolomics analyses, and synthetic products, palmitic acid (PA), were used as the intermediary agent. After a screening study, fatty acid synthase (FASN) was identified as the main targeted protein, and AhR activation regulated "HDAC3-acetylation" signals but not glycosylation to enhance FASN degradation. Furthermore, results of bioinformatics analysis and others showed that after being activated, AhR targeted miR-193a-3p to control HDAC3 transcription. Collectively, AhR activation inhibited ECM deposition and alleviated intestinal fibrosis by limiting fatty acid synthesis subsequent to the inhibition of "miR-193a-3p-HDAC3-FASN" signals.

Exploring the regulatory role of non-coding RNAs in fiber development and direct regulation of GhKCR2 in the fatty acid metabolic pathway in upland cotton.

Cotton fiber holds immense importance as the primary raw material for the textile industry. Consequently, comprehending the regulatory mechanisms governing fiber development is pivotal for enhancing fiber quality. Our study aimed to construct a regulatory network of competing endogenous RNAs (ceRNAs) and assess the impact of non-coding RNAs on gene expression throughout fiber development. Through whole transcriptome data analysis, we identified differentially expressed genes (DEGs) regulated by non-coding RNA (ncRNA) that were predominantly enriched in phenylpropanoid biosynthesis and the fatty acid elongation pathway. This analysis involved two contrasting phenotypic materials (J02-508 and ZRI015) at five stages of fiber development. Additionally, we conducted a detailed analysis of genes involved in fatty acid elongation, including KCS, KCR, HACD, ECR, and ACOT, to unveil the factors contributing to the variation in fatty acid elongation between J02-508 and ZRI015. Through the integration of histochemical GUS staining, dual luciferase assay experiments, and correlation analysis of expression levels during fiber development stages for lncRNA MSTRG.44818.23 (MST23) and GhKCR2, we elucidated that MST23 positively regulates GhKCR2 expression in the fatty acid elongation pathway. This identification provides valuable insights into the molecular mechanisms underlying fiber development, emphasizing the intricate interplay between non-coding RNAs and protein-coding genes.

PI3K/AKT mediated De novo fatty acid synthesis regulates RIG-1/MDA-5-dependent type I IFN responses in BVDV-infected CD8+T cells.

Bovine viral diarrhea virus (BVDV) has caused massive economic losses in the cattle business worldwide. Fatty acid synthase (FASN), a key enzyme of the fatty acid synthesis (FAS) pathway, has been shown to support virus replication. To investigate the role of fatty acids (FAs) in BVDV infection, we infected CD8+T lymphocytes obtained from healthy cattle with BVDV in vitro. During early cytopathic (CP) and noncytopathic (NCP) BVDV infection in CD8+ T cells, there is an increase in de novo lipid biosynthesis, resulting in elevated levels of free fatty acids (FFAs) and triglycerides (TG). BVDV infection promotes de novo lipid biosynthesis in a dose-dependent manner. Treatment with the FASN inhibitor C75 significantly reduces the phosphorylation of PI3K and AKT in BVDV-infected CD8+ T cells, while inhibition of PI3K with LY294002 decreases FASN expression. Both CP and NCP BVDV strains promote de novo fatty acid synthesis by activating the PI3K/AKT pathway. Further investigation shows that pharmacological inhibitors targeting FASN and PI3K concurrently reduce FFAs, TG levels, and ATP production, effectively inhibiting BVDV replication. Conversely, the in vitro supplementation of oleic acid (OA) to replace fatty acids successfully restored BVDV replication, underscoring the impact of abnormal de novo fatty acid metabolism on BVDV replication. Intriguingly, during BVDV infection of CD8+T cells, the use of FASN inhibitors prompted the production of IFN-α and IFN-ß, as well as the expression of interferon-stimulated genes (ISGs). Moreover, FASN inhibitors induce TBK-1 phosphorylation through the activation of RIG-1 and MDA-5, subsequently activating IRF-3 and ultimately enhancing the IFN-1 response. In conclusion, our study demonstrates that BVDV infection activates the PI3K/AKT pathway to boost de novo fatty acid synthesis, and inhibition of FASN suppresses BVDV replication by activating the RIG-1/MDA-5-dependent IFN response.

Androgen signaling inhibits de novo lipogenesis to alleviate lipid deposition in zebrafish.

Testosterone is closely associated with lipid metabolism and known to affect body fat composition and muscle mass in males. However, the mechanisms by which testosterone acts on lipid metabolism are not yet fully understood, especially in teleosts. In this study, cyp17a1-/- zebrafish ( Danio rerio) exhibited excessive visceral adipose tissue (VAT), lipid content, and up-regulated expression and activity of hepatic de novo lipogenesis (DNL) enzymes. The assay for transposase accessible chromatin with sequencing (ATAC-seq) results demonstrated that chromatin accessibility of DNL genes was increased in cyp17a1-/- fish compared to cyp17a1+/+ male fish, including stearoyl-CoA desaturase ( scd) and fatty acid synthase ( fasn). Androgen response element (ARE) motifs in the androgen signaling pathway were significantly enriched in cyp17a1+/+ male fish but not in cyp17a1-/- fish. Both androgen receptor ( ar)-/- and wild-type (WT) zebrafish administered with Ar antagonist flutamide displayed excessive visceral adipose tissue, lipid content, and up-regulated expression and activity of hepatic de novo lipogenesis enzymes. The Ar agonist BMS-564929 reduced the content of VAT and lipid content, and down-regulated acetyl-CoA carboxylase a ( acaca), fasn, and scd expression. Mechanistically, the rescue effect of testosterone on cyp17a1-/- fish in terms of phenotypes was abolished when ar was additionally depleted. Collectively, these findings reveal that testosterone inhibits lipid deposition by down-regulating DNL genes via Ar in zebrafish, thus expanding our understanding of the relationship between testosterone and lipid metabolism in teleosts.

Knockdown of PROX1 promotes milk fatty acid synthesis by targeting PPARGC1A in dairy goat mammary gland.

Goat milk is rich in various fatty acids that are beneficial to human health. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) and RNA-seq analyses of goat mammary glands at different lactation stages revealed a novel lactation regulatory factor, Prospero homeobox 1 (PROX1). However, the mechanism whereby PROX1 regulates lipid metabolism in dairy goats remains unclear. We found that PROX1 exhibits the highest expression level during peak lactation period. PROX1 knockdown enhanced the expression of genes related to de novo fatty acid synthesis (e.g., SREBP1 and FASN) and triacylglycerol (TAG) synthesis (e.g., DGAT1 and GPAM) in goat mammary epithelial cells (GMECs). Consistently, intracellular TAG and lipid droplet contents were significantly increased in PROX1 knockdown cells and reduced in PROX1 overexpression cells, and we observed similar results in PROX1 knockout mice. Following PROX1 overexpression, RNA-seq showed a significant upregulation of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PPARGC1A) expression. Further, PPARGC1A knockdown attenuated the inhibitory effects of PROX1 on TAG contents and lipid-droplet formation in GMECs. Moreover, we found that PROX1 promoted PPARGC1A transcription via the PROX1 binding sites (PBSs) located in the PPARGC1A promoter. These results suggest a novel target for manipulating the goat milk-fat composition and improving the quality of goat milk.

13C-SpaceM: Spatial single-cell isotope tracing reveals heterogeneity of de novo fatty acid synthesis in cancer.

Metabolism has emerged as a key factor in homeostasis and disease including cancer. Yet, little is known about the heterogeneity of metabolic activity of cancer cells due to the lack of tools to directly probe it. Here, we present a novel method, 13C-SpaceM for spatial single-cell isotope tracing of glucose-dependent de novo lipogenesis. The method combines imaging mass spectrometry for spatially-resolved detection of 13C6-glucose-derived 13C label incorporated into esterified fatty acids with microscopy and computational methods for data integration and analysis. We validated 13C-SpaceM on a spatially-heterogeneous normoxia-hypoxia model of liver cancer cells. Investigating cultured cells, we revealed single-cell heterogeneity of lipogenic acetyl-CoA pool labelling degree upon ACLY knockdown that is hidden in the bulk analysis and its effect on synthesis of individual fatty acids. Next, we adapted 13C-SpaceM to analyze tissue sections of mice harboring isocitrate dehydrogenase (IDH)-mutant gliomas. We found a strong induction of de novo fatty acid synthesis in the tumor tissue compared to the surrounding brain. Comparison of fatty acid isotopologue patterns revealed elevated uptake of mono-unsaturated and essential fatty acids in the tumor. Furthermore, our analysis uncovered substantial spatial heterogeneity in the labelling of the lipogenic acetyl-CoA pool indicative of metabolic reprogramming during microenvironmental adaptation. Overall, 13C-SpaceM enables novel ways for spatial probing of metabolic activity at the single cell level. Additionally, this methodology provides unprecedented insight into fatty acid uptake, synthesis and modification in normal and cancerous tissues.

Dimethyloxalylglycine Suppresses SREBP1c and Lipogenic Gene Expressions in Hepatocytes Independently of HIF1A.

Dimethyloxalylglycine (DMOG) is a representative inhibitor of the prolyl hydroxylase domain (PHD), which mediates the degradation of hypoxia-inducible factor-1-alpha (HIF1A). DMOG exerts its pharmacological effects via the canonical pathway that involves PHD inhibition; however, it remains unclear whether DMOG affects lipogenic gene expression in hepatocytes. We aimed to elucidate the effects of DMOG on sterol regulatory element-binding protein-1c (SREBP1c), a master regulator of fatty acid synthesis in hepatocytes. DMOG treatment inhibited SREBP1c mRNA and protein expression in HepG2 and AML12 hepatocytes and reduced the transcript levels of SREBP1c-regulated lipogenic genes. A luciferase reporter assay revealed that DMOG inhibited the transcriptional activity of SREBP1c. Moreover, DMOG suppressed SREBP1c expression in mice liver. Mechanistically, treatment with DMOG enhanced the expression of HIF1A and insulin-induced gene 2 (INSIG2), which inhibits the activation of SREBP1c. However, HIF1A or INSIG2 knockdown failed to reverse the inhibitory effect of DMOG on SREBP1c expression, suggesting a redundant role of HIF1A and INSIG2 in terms of repressing SREBP1c. DMOG did not function through the canonical pathway involving inhibition of SREBP1c by PHD, highlighting the presence of non-canonical pathways that mediate its anti-lipogenic effect.

[Regulation of Aging and Lifespan by White Adipose Tissue].

Long-term caloric restriction (CR) is an effective intervention that improves whole-body metabolism, suppresses age-related pathophysiology, and extends lifespan. Although the beneficial effects of caloric restriction mediated by growth hormone/insulin-like growth factor-1 (GH/IGF-1) have been extensively studied, the mechanisms independent of GH/IGF-1 remain largely unknown. In this review, we focus on these GH/IGF-1-independent mechanisms, with a particular emphasis on the role of sterol regulatory element-binding protein 1c (SREBP-1c). CR increases the expression of SREBP-1c through the suppression of leptin signaling and enhances downstream factors involved in fatty acid synthesis in white adipose tissue (WAT). SREBP-1c also directly and indirectly increases the expression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha, a master regulator of mitochondrial biogenesis, leading to an increase in the number of mitochondria. Furthermore, SREBP-1c elevates expression of mitochondrial intermediate peptidase, which contributes to improving mitochondrial quality through the processing of sirtuin 3 into its mature form. Thus, it appears that CR exerts beneficial effects by modulating mitochondrial quantity and quality in WAT in a GH/IGF-1 signal-independent manner.

Diversity in fatty acid elongation enzymes: The FabB long-chain ß-ketoacyl-ACP synthase I initiates fatty acid synthesis in Pseudomonas putida F1.

The condensation of acetyl-CoA with malonyl-acyl carrier protein (ACP) by ß-ketoacyl-ACP synthase III (KAS III, FabH) and decarboxylation of malonyl-ACP by malonyl-ACP decarboxylase are the two pathways that initiate bacterial fatty acid synthesis (FAS) in Escherichia coli. In addition to these two routes, we report that Pseudomonas putida F1 ß-ketoacyl-ACP synthase I (FabB), in addition to playing a key role in fatty acid elongation, also initiates FAS in vivo. We report that although two P. putida F1 fabH genes (PpfabH1 and PpfabH2) both encode functional KAS III enzymes, neither is essential for growth. PpFabH1 is a canonical KAS III similar to E. coli FabH whereas PpFabH2 catalyzes condensation of malonyl-ACP with short- and medium-chain length acyl-CoAs. Since these two KAS III enzymes are not essential for FAS in P. putida F1, we sought the P. putida initiation enzyme and unexpectedly found that it was FabB, the elongation enzyme of the oxygen-independent unsaturated fatty acid pathway. P. putida FabB decarboxylates malonyl-ACP and condenses the acetyl-ACP product with malonyl-ACP for initiation of FAS. These data show that P. putida FabB, unlike the paradigm E. coli FabB, can catalyze the initiation reaction in FAS.

High levels of fatty acid-binding protein 5 excessively enhances fatty acid synthesis and proliferation of granulosa cells in polycystic ovary syndrome.

BACKGROUND: Polycystic ovary syndrome (PCOS) is one of the most complex endocrine disorders in women of reproductive age. Abnormal proliferation of granulosa cells (GCs) is an important cause of PCOS. This study aimed to explore the role of fatty acid-binding protein 5 (FABP5) in granulosa cell (GC) proliferation in polycystic ovary syndrome (PCOS) patients. METHODS: The FABP5 gene, which is related to lipid metabolism, was identified through data analysis of the gene expression profiles of GSE138518 from the Gene Expression Omnibus (GEO) database. The expression levels of FABP5 were measured by quantitative real-time PCR (qRT‒PCR) and western blotting. Cell proliferation was evaluated with a cell counting kit-8 (CCK-8) assay. Western blotting was used to assess the expression of the proliferation marker PCNA, and immunofluorescence microscopy was used to detect Ki67 expression. Moreover, lipid droplet formation was detected with Nile red staining, and qRT‒PCR was used to analyze fatty acid storage-related gene expression. RESULTS: We found that FABP5 was upregulated in ovarian GCs obtained from PCOS patients and PCOS mice. FABP5 knockdown suppressed lipid droplet formation and proliferation in a human granulosa-like tumor cell line (KGN), whereas FABP5 overexpression significantly enhanced lipid droplet formation and KGN cell proliferation. Moreover, we determined that FABP5 knockdown inhibited PI3K-AKT signaling by suppressing AKT phosphorylation and that FABP5 overexpression activated PI3K-AKT signaling by facilitating AKT phosphorylation. Finally, we used the PI3K-AKT signaling pathway inhibitor LY294002 and found that the facilitation of KGN cell proliferation and lipid droplet formation induced by FABP5 overexpression was inhibited. In contrast, the PI3K-AKT signaling pathway agonist SC79 significantly rescued the suppression of KGN cell proliferation and lipid droplet formation caused by FABP5 knockdown. CONCLUSIONS: FABP5 promotes active fatty acid synthesis and excessive proliferation of GCs by activating PI3K-AKT signaling, suggesting that abnormally high expression of FABP5 in GCs may be a novel biomarker or a research target for PCOS treatment.

Auricularia auricula-judae Attenuates the Progression of Metabolic Syndrome in High-Fat Diet-Induced Obese Rats: Enzymatic Pre-Digestion Technology Is Superior to Superfine Grinding Method.

Auricularia auricula-judae (AAJ) has been cultivated for food in China for centuries, and is also used as a folk medicine for the regulation of glucose and lipid metabolism. However, there are few studies on the effects of different processing technologies on the therapeutic efficacy of AAJ to date. This study investigated the effectiveness of the AAJ made by using superfine grinding and enzymatic pre-digestion technologies, respectively, in a high-fat diet obese rat model. It was found that oral administrations of two AAJ products significantly alleviated dyslipidemia by decreasing serum lipid levels and restoring liver functions. AAJ products made by using pre-digestion technology have appreciable potential to ameliorate lipid metabolic disorders over other products, possibly due to the higher levels of dietary fiber, crude polysaccharides, and total flavonoids released from AAJ during processing. By analysis of transcriptome sequencing and protein expression, it was clear that starch and sucrose metabolism and glycerolipid metabolism-related factors involved in fatty acid synthesis and metabolism in the liver of obese rats were significantly improved. This study gives further evidence that AAJ significantly ameliorates the progression of glucose and lipid metabolism in obese rats. Moreover, this study demonstrated for the first time that the pre-digestion method may be a better and more efficient processing approach for the improvement of AAJ bioavailability.

Sulforaphane impedes mitochondrial reprogramming and histone acetylation in polarizing M1 (LPS) macrophages.

M1 (LPS) macrophages are characterized by a high expression of pro-inflammatory mediators, and distinct metabolic features that comprise increased glycolysis, a broken TCA cycle, or impaired OXPHOS with augmented mitochondrial ROS production. This study investigated whether the phytochemical sulforaphane (Sfn) influences mitochondrial reprogramming during M1 polarization, as well as to what extent this can contribute to Sfn-mediated inhibition of M1 marker expression in murine macrophages. The use of extracellular flux-, metabolite-, and immunoblot analyses as well as fluorescent dyes indicative for mitochondrial morphology, membrane potential or superoxide production, demonstrated that M1 (LPS/Sfn) macrophages maintain an unbroken TCA cycle, higher OXPHOS rate, boosted fusion dynamics, lower membrane potential, and less superoxide production in their mitochondria when compared to control M1 (LPS) cells. Sustained OXPHOS and TCA activity but not the concomitantly observed high dependency on fatty acids as fuel appeared necessary for M1 (LPS/Sfn) macrophages to reduce expression of nos2, il1ß, il6 and tnfα. M1 (LPS/Sfn) macrophages also displayed lower nucleo/cytosolic acetyl-CoA levels in association with lower global and site-specific histone acetylation at selected pro-inflammatory gene promoters than M1 (LPS), evident in colorimetric coupled enzyme assays, immunoblot and ChIP-qPCR analyses, respectively. Supplementation with acetate or citrate was able to rescue both histone acetylation and mRNA expression of the investigated M1 marker genes in Sfn-treated cells. Overall, Sfn preserves mitochondrial functionality and restricts indispensable nuclear acetyl-CoA for histone acetylation and M1 marker expression in LPS-stimulated macrophages.

Dietary supplementation of magnolol alleviates fatty liver hemorrhage syndrome in postpeak Xinhua laying hens via regulation of liver lipid metabolism.

As a metabolic disease, fatty liver hemorrhagic syndrome (FLHS) has emerged as a major cause of noninfectious mortality in laying hens, resulting in substantial economic losses to the poultry industry. This study aimed to investigate the therapeutic effects of magnolol on FLHS in postpeak laying hen model, focusing on lipid metabolism, antioxidative capacity, and potential molecular mechanisms of action. We selected 150 Xinhua laying hens aged 50 wk and divided them into normal diet group (ND), high-fat diet group (HFD), 100 mg/kg magnolol group (MG100), 300 mg/kg magnolol group (MG300), 500 mg/kg magnolol group (MG500) on average. The experiment lasted for 6 wk, and liver samples were collected from the hens at the end of the experiment. The results demonstrated that the inclusion of magnolol in the diet had a significant impact on various factors. It led to a reduction in weight, an increase in egg production rate, a decrease in blood lipid levels, and an improvement in abnormal liver function, liver steatosis, and oxidative stress. These effects were particularly prominent in the MG500 group. The RNA-Seq analysis demonstrated that in the MG500 group, there was a down-regulation of genes associated with fatty acid synthesis (Acc, Fasn, Scd, Srebf1, Elovl6) compared to the HFD group. Moreover, genes related to fatty acid oxidation (CPT1A and PGC1α) were found to be up-regulated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of these differentially expressed genes indicated their enrichment in the PPAR signaling pathway. These findings demonstrate that magnolol can mitigate FLHS by inhibiting fatty acid synthesis and promoting fatty acid oxidation. This discovery offers a novel approach for treating FLHS in laying hens, reducing the economic losses associate with FLHS.

STK11 (LKB1) mutation suppresses ferroptosis in lung adenocarcinoma by facilitating monounsaturated fatty acid synthesis.

Serine/threonine kinase 11 (STK11), a tumor suppressor gene, exhibits frequent mutations in lung adenocarcinoma (LUAD). However, the specific molecular mechanisms by which STK11 mutations exert an influence on the biosynthesis of monounsaturated fatty acids (MUFAs) and subsequently affect ferroptosis in LUAD remain indistinct. In this study, bioinformatic analysis was employed to probe into the linkage between STK11 and key inhibitory genes of ferroptosis, namely SLC7A11 and SCD1, in LUAD tissues. Quantitative reverse transcription polymerase chain reaction was employed to assess the expression of STK11 in both wild-type and mutant STK11 LUAD cells, cell counting kit-8 to assess cell viability, and flow cytometry to detect apoptosis. A transmission electron microscope was utilized to observe mitochondrial morphology, and Western blot to ascertain the protein expression of STK11, ferroptosis-related proteins, and the enzyme SCD1 involved in MUFA synthesis. Oil red O staining was employed to test the distribution of lipid droplets in cancer cells, and a lipid quantification method to measure the content of MUFAs. Commercial kits were employed to assess the levels of lipid reactive oxygen species, malondialdehyde, glutathione, and Fe2+ in cells. The result revealed a negative correlation between STK11 and SLC7A11 as well as SCD1, with STK11 expression downregulated in mutant STK11 LUAD cells. Furthermore, STK11 mutations were found to suppress ferroptosis in LUAD cells by affecting MUFA synthesis. Subsequent rescue assays demonstrated that STK11 mutations hindered ferroptosis by impacting the synthesis of MUFAs in LUAD cells. This study provided evidence that STK11 mutations suppressed ferroptosis in LUAD cells by promoting MUFA synthesis, thus offering a novel research direction in the management of LUAD.

The Role of SCAP/SREBP as Central Regulators of Lipid Metabolism in Hepatic Steatosis.

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) is rapidly increasing worldwide at an alarming pace, due to an increase in obesity, sedentary and unhealthy lifestyles, and unbalanced dietary habits. MASLD is a unique, multi-factorial condition with several phases of progression including steatosis, steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. Sterol element binding protein 1c (SREBP1c) is the main transcription factor involved in regulating hepatic de novo lipogenesis. This transcription factor is synthesized as an inactive precursor, and its proteolytic maturation is initiated in the membrane of the endoplasmic reticulum upon stimulation by insulin. SREBP cleavage activating protein (SCAP) is required as a chaperon protein to escort SREBP from the endoplasmic reticulum and to facilitate the proteolytic release of the N-terminal domain of SREBP into the Golgi. SCAP inhibition prevents activation of SREBP and inhibits the expression of genes involved in triglyceride and fatty acid synthesis, resulting in the inhibition of de novo lipogenesis. In line, previous studies have shown that SCAP inhibition can resolve hepatic steatosis in animal models and intensive research is going on to understand the effects of SCAP in the pathogenesis of human disease. This review focuses on the versatile roles of SCAP/SREBP regulation in de novo lipogenesis and the structure and molecular features of SCAP/SREBP in the progression of hepatic steatosis. In addition, recent studies that attempt to target the SCAP/SREBP axis as a therapeutic option to interfere with MASLD are discussed.