Fatty Acid Synthesis Pathway Research Articles

Mitochondrial Phosphopantetheinylation is Required for Oxidative Function.

4'-phosphopantetheinyl (4'PP) groups are essential co-factors added to target proteins by p hospho p antetheinyl transferase (PPTase) enzymes. Although mitochondrial 4'PP-modified proteins have been described for decades, a mitochondrially-localized PPTase has never been found in mammals. We discovered that the cytoplasmic PPTase a mino a dipate s emialdehyde d ehydrogenase p hospho p antetheinyl t ransferase (AASDHPPT) is required for mitochondrial respiration and oxidative metabolism. Loss of AASDHPPT results in failed 4'-PP modification of the mitochondrial acyl carrier protein and blunted activity of the mitochondrial fatty acid synthesis (mtFAS) pathway. We found that in addition to its cytoplasmic localization, AASDHPPT localizes to the mitochondrial matrix via an N-terminal mitochondrial targeting sequence contained within the first 13 amino acids of the protein. Our data show that this novel mitochondrial localization of AASDHPPT is required to support mtFAS activity and oxidative function. We further identify two variants of uncertain significance in AASDHPPT that are likely pathogenic in humans due to loss of mtFAS activity.

An endoplasmic reticulum localized acetyl-CoA transporter is required for efficient fatty acid synthesis in Toxoplasma gondii.

Toxoplasma gondii is an obligate intracellular parasite that can infect humans and diverse animals. Fatty acids are critical for the growth and proliferation of T. gondii, which has at least two pathways to synthesize fatty acids, including the type II de novo synthesis pathway in the apicoplast and the elongation pathway in the endoplasmic reticulum (ER). Acetyl-CoA is the key substrate for both fatty acid synthesis pathways. In the apicoplast, acetyl-CoA is mainly provided by the pyruvate dehydrogenase complex. However, how the ER acquires acetyl-CoA is not fully understood. Here, we identified a putative acetyl-CoA transporter (TgAT1) that localized to the ER of T. gondii. Deletion of TgAT1 impaired parasite growth and invasion in vitro and attenuated tachyzoite virulence in vivo. Metabolic tracing using 13C-acetate found that loss of TgAT1 reduced the incorporation of 13C into certain fatty acids, suggesting reduced activities of elongation. Truncation of AT1 was previously reported to confer resistance to the antimalarial compound GNF179 in Plasmodium falciparum. Interestingly, GNF179 had much weaker inhibitory effect on Toxoplasma than on Plasmodium. In addition, deletion of AT1 did not affect the susceptibility of Toxoplasma to GNF179, suggesting that this compound might be taken up differently or has different inhibitory mechanisms in these parasites. Together, our data show that TgAT1 has important roles for parasite growth and fatty acid synthesis, but its disruption does not confer GNF179 resistance in T. gondii.

HIF1A/PCDH7 axis mediates fatty acid synthesis and metabolism to inhibit lung adenocarcinoma anoikis.

Aberrantly expressed PCDH7 participates in the malignant progression of many cancers. PCDH7 has been newly discovered as a risk factor in lung cancer, but its functional study in lung adenocarcinoma (LUAD) has not been conducted yet. This study aimed to investigate the functional role of PCDH7 in LUAD. Bioinformatics analyzed the expression of PCDH7 and HIF1A in LUAD tissues, predicted the binding sites between the two, analyzed the clinicopathological relevance of PCDH7 and examined the pathway enrichment of PCDH7. Expression of PCDH7 and HIF1A in LUAD cells was analyzed by RT-qPCR. A nude mouse transplantation tumor model was constructed to analyze the effect of PCDH7 on tumor growth in vivo. The binding relationship between PCDH7 and HIF1A was confirmed by chromatin immunoprecipitation experiments and the dual-luciferase assay. Cell viability was detected with Cell Counting Kit-8. Triglyceride content and Caspase3 activity were measured using corresponding reagent kits. FASN and ACC1 expression was determined utilizing western blot. PCDH7 was highly expressed in LUAD and correlated with patients' overall survival time and N stage. In vitro and in vivo experiments confirmed that PCDH7 could promote LUAD growth and anoikis resistance. Moreover, overexpression of PCDH7 markedly increased the content of triglycerides in cells and promoted the expression of FASN and ACC1 proteins to inhibit LUAD cell anoikis. Cell rescue experiment confirmed that HIF1A activated PCDH7 to suppress LUAD anoikis by promoting fatty acid (FA) synthesis and metabolism. Our findings demonstrated that the HIF1A/PCDH7 axis suppressed LUAD anoikis by promoting FA synthesis and metabolism. The FA synthesis pathway might be a key pathway regulated by PCDH7 in LUAD anoikis.

Prophages divert Staphylococcus aureus defenses against host lipids

Phages are ubiquitous in bacteria, including clinical Staphylococcus aureus, where Sfi 21/Sa3 phages often integrate into the hlb gene, which encodes Hlb sphingomyelinase. This integration acts as a rapid regulatory switch for Hlb production. Our findings suggest that Sfi 21/Sa3 prophages and Hlb activity influence S. aureus fitness by modulating the incorporation of the toxic linoleic acid (C18:2) from serum into the bacterial membrane. This process relies on C18:2 derived from 1,3-diglyceride, facilitated by the FakB1 kinase subunit. Palmitic acid (C16), primarily released from serum through Hlb activity, competes with C18:2 for FakB1. This mechanism contributes to adaptation to AFN-1252, an antibiotic inhibiting the fatty acid synthesis pathway (anti-FASII). Since S. aureus relies on exogenous fatty acids for growth, AFN-1252 treatment leads to increased proportion of C18:2 in the membrane. Furthermore, Hlb inhibition, whether by prophage insertion, gene inactivation, or enzyme inhibition, delays S. aureus adaptation, resulting in a higher proportion of C18:2 in the membrane. This study sheds light on the role of lipid environments in infections and may contribute to the accurate prediction of infection risks and therapeutic efficacy. Moreover, since both anti-FASII agent and Hlb inhibitor enhance C18:2 incorporation, they represent potential candidates for combined strategies against S. aureus.

A temperature-sensitive metabolic valve and a transcriptional feedback loop drive rapid homeoviscous adaptation in Escherichia coli

All free-living microorganisms homeostatically maintain the fluidity of their membranes by adapting lipid composition to environmental temperatures. Here, we quantify enzymes and metabolic intermediates of the Escherichia coli fatty acid and phospholipid synthesis pathways, to describe how this organism measures temperature and restores optimal membrane fluidity within a single generation after a temperature shock. A first element of this regulatory system is a temperature-sensitive metabolic valve that allocates flux between the saturated and unsaturated fatty acid synthesis pathways via the branchpoint enzymes FabI and FabB. A second element is a transcription-based negative feedback loop that counteracts the temperature-sensitive valve. The combination of these elements accelerates membrane adaptation by causing a transient overshoot in the synthesis of saturated or unsaturated fatty acids following temperature shocks. This strategy is comparable to increasing the temperature of a water bath by adding water that is excessively hot rather than adding water at the desired temperature. These properties are captured in a mathematical model, which we use to show how hard-wired parameters calibrate the system to generate membrane compositions that maintain constant fluidity across temperatures. We hypothesize that core features of the E. coli system will prove to be ubiquitous features of homeoviscous adaptation systems.

Recombinant leptins affect lipid metabolism in hepatocytes of Cynoglossus semilaevis

Leptin is a peptide hormone primarily produced by adipose tissue, which plays a crucial role in regulating energy balance by controlling appetite and energy expenditure. To better understand the intricate physiological functions of leptin in hepatocytes in tongue sole (Cynoglossus semilaevis), this study presents an integrated transcriptomic and metabolomic analysis of tongue sole hepatocytes following stimulation with lepA and lepB. Comparative analysis identified 2971 and 2900 upregulated differentially expressed genes (DEGs) and 1895 and 1821 downregulated DEGs in response to lepA and lepB stimulation, respectively. Notably, 5706 genes were commonly regulated by both stimulations, suggesting overlapping functional roles of these two leptin proteins. GO and KEGG enrichment analysis indicated significant enrichment in immune response (JAK-STAT signaling pathway, NF-κB signaling pathway, etc.) and lipid metabolism pathways, such as fatty acid synthesis, with similar findings for lepB. Metabolomic analysis demonstrated clear separation between treatment and control groups, with 34 medium- to long-chain fatty acids and numerous differentially expressed metabolites (DEMs) identified. KEGG analysis of the metabolome paralleled the transcriptomic findings, with shared pathways in lipid metabolism and immune function. Finally, joint analysis highlighted co-enrichment in linoleic acid metabolism and leishmaniasis pathways. Detailed mechanistic insights revealed the activation of JAK-STAT and NF-κB signaling pathways, modulation of arachidonic acid metabolism, and the influence on the MAPK signaling pathway. Additionally, lepA uniquely co-enriched in the fatty acid synthesis pathway, with specific gene regulation affecting the synthesis of various fatty acids. The study concluded that lepA and lepB exerted significant regulatory effects on lipid metabolism and immune responses in tongue sole hepatocytes through complex molecular networks. To our current knowledge, this represents the first direct evidence of leptin's role in immune function within teleost fish and offers valuable insights into the molecular mechanisms of lipid metabolism underlying the actions of lepA and lepB.

Genetic Loci Mining and Candidate Gene Analysis for Determining Fatty Acid Composition in Rice

Fatty acid composition and its proportions are critical to the nutritional value and storage quality of rice (Oryza sativa L.) as the third major nutrient component in this staple food. This study involved crossing an indica rice variety, Huazhan (HZ), as the male parent, with a japonica variety, Nekken2, as the female parent, to produce the F1 generation. Subsequently, a population of 120 recombinant inbred lines (RILs) was developed through multiple generations of self-breeding. By utilizing a high-density molecular genetic linkage map and phenotypic data of four fatty acid components, we identified a total of 14 quantitative trait loci (QTLs) related to fatty acid composition across chromosomes 1, 3, 4, 6, 8, and 9. These included two QTLs for C14 content, three for C16:0 content, six for C18:1 content, and three for C18:2 content. Notably, the QTL qCOPT4.2 exhibited a high LOD score of 5.22. Within QTL intervals, genes such as OsACX3 and SLG affecting grain length were identified. The expression of candidate genes within these intervals was assessed and further analyzed by using quantitative real-time PCR. Genes such as LOC_Os01g15000, LOC_Os04g47120, LOC_Os04g49194, LOC_Os06g22080, LOC_Os06g23870, LOC_Os06g24704, LOC_Os06g30780, LOC_Os08g44840, and LOC_Os09g36860 were found to regulate fatty acid synthesis or metabolic pathways, potentially enhancing fatty acid content in rice. These QTLs are indispensable for breeding rice varieties with improved fatty acid profiles, offering new genetic resources for enhancing the nutritional and storage qualities of rice.

Individual and combined effects of sodium dichloroisocyanurate and isothiazolinone on the cyanobacteria-Vallisneria natans-microbe aquatic ecosystem

The use of algaecides to control high-density cyanobacterial blooms is often complicated by secondary pollution and the toxicity to non-target organisms. This study investigates the individual and combined effects of sodium dichloroisocyanurate (NaDCC, 5, 50, and 100 mg/L) and isothiazolinone (0.1, 0.5, and 1.5 mg/L) on a cyanobacteria-Vallisneria natans-microbe aquatic ecosystem, focusing on their interactions and ecological impacts. Results indicate that NaDCC could achieve a higher algae removal rate than isothiazolinone within 15 days, but has a greater negative effect on Vallisneria natans. Both algaecides disrupt nutrient and secondary metabolite balances at low and high concentrations, increasing nutrient loads and harmful substances. Optimal results were obtained with low concentrations of NaDCC (5 mg/L) and isothiazolinone (0.1 mg/L), effectively controlling cyanobacteria while minimizing harm to Vallisneria natans and reducing nutrient loads and microcystin accumulation. Algaecide application enhanced microbial diversity in water and leaves, shifting the dominant community from cyanobacteria to organisms adapted to the post-cyanobacterial decay environment. Metabolomic analysis indicated increased secretion of lipids and organic acids by cyanobacteria in response to algaecide stress. High concentrations of NaDCC and isothiazolinone disrupted nitrogen metabolism in cyanobacteria and induced ROS overproduction, affecting unsaturated fatty acid synthesis and other metabolic pathways. These findings highlight the importance of exploring different combinations of algaecides to reduce their concentrations, balance algal control with ecological stability, and offer insights for effective eutrophication management.

Retinoid X Receptor Signaling Mediates Cancer Cell Lipid Metabolism in the Leptomeninges.

Cancer cells metastatic to the leptomeninges encounter a metabolically-challenging extreme microenvironment. To understand adaptations to this space, we subjected leptomeningeal-metastatic (LeptoM) mouse breast and lung cancers isolated from either the leptomeninges or orthotopic primary sites to ATAC-and RNA-sequencing. When inhabiting the leptomeninges, the LeptoM cells demonstrated transcription downstream of retinoid-X-receptors (RXRs). We found evidence of local retinoic acid (RA) generation in both human leptomeningeal metastasis and mouse models in the form of elevated spinal fluid retinol and expression of RA-generating dehydrogenases within the leptomeningeal microenvironment. Stimulating LeptoM cells with RA induced expression of transcripts encoding de novo fatty acid synthesis pathway enzymes in vitro . In vivo , while deletion of Stra6 did not alter cancer cell leptomeningeal growth, knockout of Rxra/b/g interrupted cancer cell lipid biosynthesis and arrested cancer growth. These observations illustrate a mechanism whereby metastatic cancer cells awake locally-generated developmental cues for metabolically reprograming, suggesting novel therapeutic approaches.

The double-edged role of FASII regulator FabT in Streptococcus pyogenes infection.

In Streptococcus pyogenes, the type II fatty acid (FA) synthesis pathway FASII is feedback-controlled by the FabT repressor bound to an acyl-Acyl carrier protein. Although FabT defects confer reduced virulence in animal models, spontaneous fabT mutants arise in vivo. We resolved this paradox by characterizing the conditions and mechanisms requiring FabT activity, and those promoting fabT mutant emergence. The fabT defect leads to energy dissipation, limiting mutant growth on human tissue products, which explains the FabT requirement during infection. Conversely, emerging fabT mutants show superior growth in biotopes rich in saturated FAs, where continued FASII activity limits their incorporation. We propose that membrane alterations and continued FASII synthesis are the primary causes for increased fabT mutant mortality in nutrient-limited biotopes, by failing to stop metabolic consumption. Our findings elucidate the rationale for emerging fabT mutants that improve bacterial survival in lipid-rich biotopes, but lead to a genetic impasse for infection.

Abstract C103: Exploring ethnicity-specific molecular mechanism of cholesterol and fatty acid synthesis pathway in Hispanic colorectal cancer

Abstract Colorectal cancer (CRC) is the most prevalent gastrointestinal cancer, the third most common malignancy and the second leading cause of cancer-related mortality worldwide. The American Cancer Society (ACS) estimates 152,810 new cases of colorectal cancer, with an estimated 53,010 deaths in 2024. Typically diagnosed in older adults, CRC incidence is rising among younger individuals, particularly in Hispanics (16.5%) compared to non-Hispanic whites (8.7%). Due to the lack of timely screenings in this ethnic group, further research is crucial to identify novel biomarkers and therapeutic targets for improved early detection and intervention. To accomplish this goal, we performed RNA-sequencing of Hispanic and non-Hispanic White (NHW) CRC tissues. The transcriptomic analysis revealed differential gene expression patterns in Hispanic and NHW populations when compared to respective normal adjacent tissues (NATs). We identified 3577 differentially expressed genes (DEGs) in Hispanic CRC samples and 2971 DEGs in NHW CRC samples, of which 1831 DEGs were unique to Hispanic. Based on the preliminary analysis we hypothesized that unique DEGs from the Hispanic population could help identify potential pathways contributing to CRC progression. Among these 1831 unique DEGs, many of the genes are associated with cholesterol and fatty acid synthesis pathway. The cholesterol biosynthesis pathway is a highly diverse and interconnected signaling pathway, playing essential roles in cellular function and systemic homeostasis. Its complexity and regulatory mechanisms make it a critical area of study in cancer. Studies indicate that Hispanics and African Americans with high cholesterol tend to have higher Body mass index (BMI) levels compared to Whites which has an increased risk of colorectal cancer. However, the role of cholesterol metabolism and fatty acid metabolism in CRC have not been studied from the Hispanic health disparities perspective. From the 1831 DEGs, we selected those in the cholesterol and fatty acid synthesis pathways with significant log2 fold changes (≤ -2 or ≥ +2) and adjusted p-values (FDR ≤ 0.05). Our bioinformatics analysis identified four key DEGs: LCN2, DHCR7, PCSK9 and SQLE. The expression levels of these genes were examined in Hispanic CRC vs. NHW CRC tissue samples using qRT-PCR. Elevated expression of LCN2 and SQLE was observed in late-stage Hispanic CRC tissues compared to NHW CRC tissues, while DHCR7 exhibited high expression in early-stage Hispanic CRC. On the other hand, PCSK9 showed low expression in both early and late stages of Hispanic CRC, suggesting potential ethnicity-specific molecular signatures in CRC progression. Moving forward, protein level studies and functional analysis of these DEGs in Hispanic CRC tissues and organoids will enhance our understanding of the role of cholesterol and fatty acid synthesis pathway proteins. Thus, elucidating novel molecular mechanisms underlying CRC progression could lead to identification of potential Hispanic specific biomarkers and therapeutic targets for early diagnosis and intervention. Citation Format: Somrita Roy, Soumya Nair, MD Zahirul Islam Khan, Sourav Roy. Exploring ethnicity-specific molecular mechanism of cholesterol and fatty acid synthesis pathway in Hispanic colorectal cancer [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C103.

Identification of genome-wide copy number variation-driven subtypes for the treatment and prognostic prediction of esophageal carcinoma

BackgroundEsophageal carcinoma (ESCA) is a frequently detected gastrointestinal cancer. Copy number variants (CNVs) have a dramatic impact on the screening, diagnosis and prognostic prediction of cancers. However, the mechanism of action of CNVs on ESCA occurrence and progression remains unclear. MethodsESCA samples from The Cancer Genome Atlas (TCGA) were typed by consensus clustering using CNV-associated genes. Weighted Gene Co-Expression Network Analysis (WGCNA) was used to section gene modules closely related to the two clusters, and sub-networks were constructed as hub genes. In addition, seven prognosis-correlated genes were further screened and retained by multivariate Cox regression analysis to develop a prognostic assessment model. The ssGSEA algorithm assessed energy metabolism levels in patients from different clusters and risk groups. Finally, quantitative real-time PCR (qRT-PCR) and live-dead cell staining verified the expression of genes associated with CNV risk scores. ResultsESCA was classified into two subtypes based on CNV values. Compared with cluster 1, cluster 2 had significantly higher level of immune score and tumor-associated immune cell infiltration as well as a noticeably better overall survival. The three modules most associated with the two clusters were identified by WGCNA, and a prognostic model with a strong prediction performance was constructed with their genes. Glycolysis, lactate metabolism, fatty acid synthesis, glutathione, methionine, and tryptophan metabolic pathway enrichment scores were remarkably higher in patients in cluster 1 and the high-risk group than in cluster 2 and the low-risk group. Knockdown PIK3C2A promoted ESCA cells apoptosis and inhibited cell vibiality. ConclusionThe current research maybe provides new understanding for the pathogenesis of ESCA based on CNV, providing an effective guidance for its clinical diagnosis and prognostic evaluation.

Effect of NH4Cl supplementation on growth, photosynthesis, and triacylglycerol content in Chlamydomonas reinhardtii under mixotrophic cultivation.

Ammonium chloride (NH4Cl) is one of the nitrogen sources for microalgal cultivation. An excessive amounts of NH4Cl are toxic for microalgae. However, combining mixotrophic conditions and excessive quantities of NH4Cl positively affects microalgal biomass and lipid production. In this study, we investigated the impact of NH4Cl on the growth, biomass, and triglyceride (TAG) content of the green microalga Chlamydomonas reinhardtii especially under mixotrophic conditions. Under photoautotrophic conditions (without organic carbon supplementation), adding 25 mM NH4Cl had no significant effect on microalgal growth or TAG content. However, under mixotrophic condition (with acetate supplementation), NH4Cl interfered with microalgal growth while inducing TAG content. To explore these effects further, we conducted a two-step cultivation process and found that NH4Cl reduced microalgal growth, but induced total lipid and TAG content, especially after 4-day cultivation. The photosynthesis performances showed that NH4Cl completely inhibited oxygen evolution on day 4. However, NH4Cl slightly reduced the Fv/Fm ratio indicating that the NH4Cl supplementation directly affects microalgal photosynthesis. To investigate the TAG induction effect by NH4Cl, we compared the protein expression profiles of microalgae grown mixotrophically with and without 25 mM NH4Cl using a proteomics approach. This analysis identified 1782 proteins, with putative acetate uptake transporter GFY5 and acyl-coenzyme A oxidase being overexpressed in the NH4Cl-treated group. These findings suggested that NH4Cl supplementation may stimulate acetate utilization and fatty acid synthesis pathways in microalgae cells. Our study indicated that NH4Cl supplementation can induce microalgal biomass and lipid production, particularly when combined with mixotrophic conditions.

KLF1 Activates RAC3 to Mediate Fatty Acid Synthesis and Enhance Cisplatin Resistance in Bladder Cancer Cells.

While cisplatin remains a frontline treatment for bladder cancer (BCa), the onset of resistance greatly hampers its effectiveness. RAC3 is closely linked to chemoresistance in cancer cells, but its specific role in cisplatin resistance within BCa is still elusive. RAC3 expression in BCa was analyzed using bioinformatics and quantitative polymerase chain reaction (qPCR). The gene set enrichment analysis (GSEA) identified RAC3-enriched pathways and the correlation between RAC3 and fatty acid synthase (FASN), a gene involved in fatty acid synthesis. Potential upstream transcription factors of RAC3 were predicted and their interaction with RAC3 was confirmed via dual-luciferase and chromatin immunoprecipitation (ChIP) assays. T24/DDP, a cisplatin-resistant BCa cell line, was established to probe into the regulatory role of RAC3 in cisplatin resistance. Cell proliferation was evaluated by colony formation and the IC50 values after cisplatin treatment were determined using cell counting kit-8 (CCK-8). The levels of free fatty acids and triglycerides (TGs), as well as the expression of DGAT2 and FASN proteins, were measured to gauge the extent of fatty acid synthesis in cells. Elevated expression of RAC3 was observed in BCa and the cisplatin-resistant BCa cells (T24/DDP). The knockdown of RAC3 within T24/DDP cells was demonstrated to counteract cisplatin resistance. Subsequent analyses identified RAC3 as being notably enriched in the fatty acid synthesis pathway, with Kruppel-like factor 1 (KLF1) emerging as a key upstream regulator. The overexpression of RAC3 was correlated with increased cisplatin resistance in T24/DDP cells, an effect that was mitigated by the addition of the FASN inhibitor, Orlistat. Furthermore, the downregulation of KLF1 suppressed RAC3 expression, disrupted fatty acid synthesis, and attenuated cisplatin resistance in T24/DDP cells. Conversely, the co-overexpression of RAC3 counteracted the effects conferred by KLF1 knockdown. Our study has validated that KLF1 activates RAC3 to mediate fatty acid synthesis and promote cisplatin resistance in BCa, suggesting the KLF1/RAC3 axis as a potential target for combating cisplatin-resistant BCa.

Low doses of acetyl trihexyl citrate plasticizer promote adipogenesis in hepatocytes and mice.

Accumulating epidemiological evidence underscores the association between pervasive environmental factors and an increased risk of metabolic diseases. Environmental chemicals, recognized disruptors of endocrine and metabolic processes, may contribute to the global prevalence of metabolic disorders, including obesity. Acetyl tributyl citrate (ATHC), categorized as a citric acid ester plasticizer, serves as a substitute for di-(2-ethylhexyl) phthalate (DEHP) in various everyday products. Despite its widespread use and the increasing risk of exposure in humans and animals due to its high leakage rates, information regarding the safety of exposure to environmentally relevant doses of ATHC remains limited. This study aimed to investigate the potential impact of ATHC exposure on metabolic homeostasis. Both in vivo and in vitro exposure models were used to characterize the effects induced by ATHC exposure. C57BL/6J male mice were subjected to a diet containing ATHC for 12weeks, and metabolism-related parameters were monitored and analyzed throughout and after the exposure period. Results indicated that sub-chronic dietary exposure to ATHC induced an increase in body fat percentage, elevated serum lipid levels, and increased lipid content in the liver tissue of mice. Furthermore, the effect of ATHC exposure on murine hepatocytes were examined and results indicated that ATHC significantly augmented lipid levels in AML12 hepatocytes, disrupting energy homeostasis and altering the expression of genes associated with fatty acid synthesis, uptake, oxidation, and secretion pathways. Conclusively, both in vivo and in vitro results suggest that exposure to low levels of ATHC may be linked to an elevated risk of obesity and fatty liver in mice. The potential implications of ATHC on human health warrant comprehensive evaluation in future studies.

Lipid Hydrolysis, Oxidation, and Fatty Acid Formation Pathway Mapping of Synergistically Fermented Sausage and Characterization of Lipid Mediating Genes.

Starter cultures play a significant role in lipid hydrolysis, prevention of lipid oxidation, and synthesis of fatty acid in fermented sausage, enhancing product quality. In this study, five synergistic bacterial strains were used, including Pediococcus pentosaceus (B-3), Latilactobacillus sakei DLS-24 (D-24), Latilactobacillus acidophilus DLS-29 (D-29), Lactiplantibacillus pentosus (B-1), and Lactiplantibacillus plantarum (B-2). Sausage B1B3D24 gave the highest free fatty acid with 39.45 g/100 g at 45-Day. Based on 2-thiobarbituric acid reactive substance, B2B3 contains 112.68 MDA/kg. Lipoxygenase activity displays the lowest in B1B3D24 with 0.095 μmol/min·mg followed by B2B3 with 0.145 μmol/min·mg. B1B3D24 contains 11.35 g/kg of monounsaturated fatty acid with the highest content in eicosenoic acid (C20:1) and palmitoleic acid (C16:1). The fatty acid synthesis pathway in B1B3D24 contains an active positive interaction with PUFA to increase the isotopomers of ω-3 and ω-6 fatty acids. In addition, lipid mediating genes in B1B3D24 show the highest counts in fatty-acid synthase, carbonyl reductase 4, 3-oxoacyl-[acyl-carrier-protein] synthase III, hydroxysteroid 17-beta dehydrogenase 8, and acetyl-CoA carboxylase.

Host cells reprogram lipid droplet synthesis through YY1 to resist PRRSV infection.

Metabolism in host cells can be modulated after viral infection, favoring viral survival or clearance. Here, we report that lipid droplet (LD) synthesis in host cells can be modulated by yin yang 1 (YY1) after porcine reproductive and respiratory syndrome virus (PRRSV) infection, resulting in active antiviral activity. As a ubiquitously distributed transcription factor, there was increased expression of YY1 upon PRRSV infection both in vitro and in vivo. YY1 silencing promoted the replication of PRRSV, whereas YY1 overexpression inhibited PRRSV replication. PRRSV infection led to a marked increase in LDs, while YY1 knockout inhibited LD synthesis, and YY1 overexpression enhanced LD accumulation, indicating that YY1 reprograms PRRSV infection-induced intracellular LD synthesis. We also showed that the viral components do not colocalize with LDs during PRRSV infection, and the effect of exogenously induced LD synthesis on PRRSV replication is nearly lethal. Moreover, we demonstrated that YY1 affects the synthesis of LDs by regulating the expression of lipid metabolism genes. YY1 negatively regulates the expression of fatty acid synthase (FASN) to weaken the fatty acid synthesis pathway and positively regulates the expression of peroxisome proliferator-activated receptor gamma (PPARγ) to promote the synthesis of LDs, thus inhibiting PRRSV replication. These novel findings indicate that YY1 plays a crucial role in regulating PRRSV replication by reprogramming LD synthesis. Therefore, our study provides a novel mechanism of host resistance to PRRSV and suggests potential new antiviral strategies against PRRSV infection.IMPORTANCEPorcine reproductive and respiratory virus (PRRSV) has caused incalculable economic damage to the global pig industry since it was first discovered in the 1980s. However, conventional vaccines do not provide satisfactory protection. It is well known that viruses are parasitic pathogens, and the completion of their replication life cycle is highly dependent on host cells. A better understanding of host resistance to PRRSV infection is essential for developing safe and effective strategies to control PRRSV. Here, we report a crucial host antiviral molecule, yin yang 1 (YY1), which is induced to be expressed upon PRRSV infection and subsequently inhibits virus replication by reprogramming lipid droplet (LD) synthesis through transcriptional regulation. Our work provides a novel antiviral mechanism against PRRSV infection and suggests that targeting YY1 could be a new strategy for controlling PRRSV.

Integrative proteomic-metabolomics strategy reveals the regulators and mechanism of enhancing cyclic lipopeptides in the high-cell-density fermentation of Bacillus subtilis S1702

The cyclic lipopeptides (CPs) are synthesized by Bacillus spp. with excellent surface activities, but are limited in the application due to its low yield. More CPs secretion was previously determined in Bacillus subtilis culture under high cell density fermentation (HF). To explore the regulators and mechanism of sporulation and CPs, the proteomic and metabolomics profiles were firstly analyzed. As results, 95 different-regulated proteins were concentrated in TCA cycle, amino acid and fatty acid synthesis and metabolism pathways, promoting the synthesis of precursor peptide chains, inducing fatty acid transformation, and indirectly enhancing the formation of the CPs. Moreover, the correlation proteomic-metabolomics analysis showed that the surfactin and iturin yield were promoted by upregulation of NRPS synthetase (Sfp, Ste), while the downregulation of FenB (log2FC=-2.35) restricted the synthesis of fengycin. Besides, the addition of KH2PO4 increased the expression of two-component system (PhoR/PhoP), and promoted sporulation indirectly. Furthermore, sufficient substrate in HF system promoted energy metabolism pathway to produce more ATP and maintain cell vitality. Overall, our findings firstly provide a basis for further exploring potential regulation of CPs secretion induced by HF, and could be as a novel guild for look for the regulator of target substance in fermentation.

Engineering Fatty Acid Biosynthesis in Microalgae: Recent Progress and Perspectives.

Microalgal lipids hold significant potential for the production of biodiesel and dietary supplements. To enhance their cost-effectiveness and commercial competitiveness, it is imperative to improve microalgal lipid productivity. Metabolic engineering that targets the key enzymes of the fatty acid synthesis pathway, along with transcription factor engineering, are effective strategies for improving lipid productivity in microalgae. This review provides a summary of the advancements made in the past 5 years in engineering the fatty acid biosynthetic pathway in eukaryotic microalgae. Furthermore, this review offers insights into transcriptional regulatory mechanisms and transcription factor engineering aimed at enhancing lipid production in eukaryotic microalgae. Finally, the review discusses the challenges and future perspectives associated with utilizing microalgae for the efficient production of lipids.

YBX1 as a prognostic biomarker and potential therapeutic target in hepatocellular carcinoma: A comprehensive investigation through bioinformatics analysis and in vitro study

BackgroundsY-box binding protein 1 (YBX1) is a DNA/RNA binding protein known to contribute to the progression of various malignancies, however, a comprehensive pan-cancer analysis to investigate YBX1 across a broad spectrum of cancer types has not yet been conducted. MethodsWe utilized the TIMER database for a comprehensive pan-cancer analysis and assessed YBX-1 expression via the TCGA and GEO databases. The relationship between YBX-1 expression and tumor-infiltrating cells was examined using TIMER and the R programming language. To evaluate the prognostic value of YBX1, we performed Kaplan-Meier plots and Cox regression analyses. Through LinkedOmics, we identified genes significantly correlated with YBX-1. The WEB-based Gene SeT AnaLysis Toolkit was used for KEGG pathway enrichment analysis. Additionally, using shRNA-mediated knockdown, we explored the potential role of YBX1 in tumor cell biology. ResultsOur study identifies pronounced overexpression of YBX-1 across multiple cancer types, correlating with adverse outcomes, notably in liver hepatocellular carcinoma (LIHC). A distinct association between elevated YBX-1 expression and heightened immune cell infiltration suggests YBX-1′s potential role in reshaping the tumor microenvironment. Intriguingly, our KEGG pathway analysis indicated a tight nexus between YBX-1 expression and lipid metabolism. Moreover, the suppression of YBX-1 via shRNA revealed diminished cellular proliferation and marked reductions in crucial molecules steering the fatty acid synthesis pathway, implicating YBX-1′s potential regulatory role in lipid metabolism within LIHC. ConclusionsYBX-1 serves as a favorable prognostic indicator in various cancers, particularly in liver hepatocellular carcinoma. Targeting YBX1 in HCC offers potential therapeutic strategies. This work paves the way for fresh insights into targeted therapeutic approaches for cancers, especially benefiting liver hepatocellular carcinoma patients.