Stearoyl-CoA desaturase 5 (SCD5), a Δ-9 fatty acyl desaturase in search of a function

Flow-Mediated Modulation of the Endothelial Cell Lipidome

The luminal surface of the endothelium is exposed to dynamic blood flow patterns that are known to affect endothelial cell phenotype. While many studies have documented the phenotypic changes by gene or protein expression, less is known about the role of blood flow pattern on the endothelial cell (EC) lipidome. In this study, shotgun lipidomics was conducted on human aortic ECs (HAECs) exposed to unidirectional laminar flow (UF), disturbed flow (DF), or static conditions for 48 hrs. A total of 520 individual lipid species from 17 lipid subclasses were detected. Total lipid abundance was significantly increased for HAECs exposed to DF compared to UF conditions. Despite the increase in the total lipid abundance, HAECs maintained equivalent composition of each lipid subclass (% of total lipid) under both DF and UF. However, by lipid composition (% of total subclass), 28 lipid species were significantly altered between DF and UF. Complimentary RNA sequencing of HAECs exposed to UF or DF revealed changes in transcripts involved in lipid metabolism. Shotgun lipidomics was also performed on HAECs exposed to pro-inflammatory agonists lipopolysaccharide (LPS) or Pam3CSK4 (Pam3) for 48 hrs. Exposure to LPS or Pam3 reshaped the EC lipidome in both unique and overlapping ways. In conclusion, exposure to flow alters the EC lipidome and ECs undergo stimulus-specific lipid reprogramming in response to pro-inflammatory agonist exposure. Ultimately, this work provides a resource to profile the transcriptional and lipidomic changes that occur in response to applied flow that can be accessed by the vascular biology community to further dissect and extend our understanding of endothelial lipid biology.

The association of dietary intake and plasma fatty acid panel in pancreatic cancer patients: Results from Golestan cohort study

BACKGROUND & AIMS

High mortality rate of pancreatic cancer (PC) as one of the most common cancers worldwide made it a center of attention for recent researches on its pathology, etiology, screening and early diagnosis. In previous researches, association of dietary intake and plasma levels of fatty acids with risk of pancreatic cancer was investigated. In this study we aimed to evaluate the correlation between dietary and plasma fatty acids in case and control groups.

METHODS

From 50,045 adults between 40-75 years old participated in Golestan cohort study, fifty incident cases of PC were diagnosed and 150 controls matched by age, sex and residence place were randomly selected. Dietary intakes and plasma levels of fatty acids was evaluated by validated food-frequency questionnaire (FFQ) and Gas Chromatography - Flame Ionization Detector (GC-FID), respectively. Then, Spearman's correlation was used to measure the correlation between dietary and plasma levels of fatty acids in case and control groups.

RESULTS

Among all the fatty acids, there was a significant association between plasma and dietary intake of a few fatty acids including trans fatty acids (TFA), polyunsaturated fatty acids (PUFA), 22:6n-3 and 14:0 only in control group. Only total PUFA intake modified plasma level of some fatty acids in case group. There was no difference between association of desaturase enzymes and fatty acids in case and controls.

CONCLUSIONS

Since, plasma levels of fatty acids might be influenced by recent diet, we did not find any specific differences between the associations of plasma levels of fatty acids with dietary intake of fats in case and control groups.

Metabolism-regulated ferroptosis in cancer progression and therapy

Cancer metabolism mainly includes carbohydrate, amino acid and lipid metabolism, each of which can be reprogrammed. These processes interact with each other to adapt to the complicated microenvironment. Ferroptosis is a regulated cell death induced by iron-dependent lipid peroxidation, which is morphologically different from apoptosis, necrosis, necroptosis, pyroptosis, autophagy-dependent cell death and cuprotosis. Cancer metabolism plays opposite roles in ferroptosis. On the one hand, carbohydrate metabolism can produce NADPH to maintain GPX4 and FSP1 function, and amino acid metabolism can provide substrates for synthesizing GPX4; on the other hand, lipid metabolism might synthesize PUFAs to trigger ferroptosis. The mechanisms through which cancer metabolism affects ferroptosis have been investigated extensively for a long time; however, some mechanisms have not yet been elucidated. In this review, we summarize the interaction between cancer metabolism and ferroptosis. Importantly, we were most concerned with how these targets can be utilized in cancer therapy.

Comprehensive proteomic analysis reveals omega-3 fatty acids to counteract endotoxin-stimulated metabolic dysregulation in porcine enterocytes

Omega-3 polyunsaturated fatty acids (n-3 PUFA), such as the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are reported to beneficially affect the intestinal immunity. The biological pathways modulated by n-3 PUFA during an infection, at the level of intestinal epithelial barrier remain elusive. To address this gap, we investigated the proteomic changes induced by n-3 PUFA in porcine enterocyte cell line (IPEC-J2), in the presence and absence of lipopolysaccharide (LPS) stress conditions using shotgun proteomics analysis integrated with RNA-sequencing technology. A total of 33, 85, and 88 differentially abundant proteins (DAPs) were identified in cells exposed to n-3 PUFA (DHA:EPA), LPS, and n-3 PUFA treatment followed by LPS stimulation, respectively. Functional annotation and pathway analysis of DAPs revealed the modulation of central carbon metabolism, including the glycolysis/gluconeogenesis, pentose phosphate pathway, and oxidative phosphorylation processes. Specifically, LPS caused metabolic dysregulation in enterocytes, which was abated upon prior treatment with n-3 PUFA. Besides, n-3 PUFA supplementation facilitated enterocyte development and lipid homeostasis. Altogether, this work for the first time comprehensively described the biological pathways regulated by n-3 PUFA in enterocytes, particularly during endotoxin-stimulated metabolic dysregulation. Additionally, this study may provide nutritional biomarkers in monitoring the intestinal health of human and animals on n-3 PUFA-based diets.

The intracellular growth of the vacuolar pathogen Legionella pneumophila is dependent on the acyl chain composition of host membranes

Legionella pneumophila is an accidental human bacterial pathogen that infects and replicates within alveolar macrophages causing a severe atypical pneumonia known as Legionnaires' disease. As a prototypical vacuolar pathogen L. pneumophila establishes a unique endoplasmic reticulum (ER)-derived organelle within which bacterial replication takes place. Bacteria-derived proteins are deposited in the host cytosol and in the lumen of the pathogen-occupied vacuole via a type IVb (T4bSS) and a type II (T2SS) secretion system respectively. These secretion system effector proteins manipulate multiple host functions to facilitate intracellular survival of the bacteria. Subversion of host membrane glycerophospholipids (GPLs) by the internalized bacteria via distinct mechanisms feature prominently in trafficking and biogenesis of the Legionella -containing vacuole (LCV). Conventional GPLs composed of a glycerol backbone linked to a polar headgroup and esterified with two fatty acids constitute the bulk of membrane lipids in eukaryotic cells. The acyl chain composition of GPLs dictates phase separation of the lipid bilayer and therefore determines the physiochemical properties of biological membranes - such as membrane disorder, fluidity and permeability. In mammalian cells, fatty acids esterified in membrane GPLs are sourced endogenously from de novo synthesis or via internalization from the exogenous pool of lipids present in serum and other interstitial fluids. Here, we exploited the preferential utilization of exogenous fatty acids for GPL synthesis by macrophages to reprogram the acyl chain composition of host membranes and investigated its impact on LCV homeostasis and L. pneumophila intracellular replication. Using saturated fatty acids as well as cis - and trans - isomers of monounsaturated fatty acids we discovered that under conditions promoting lipid packing and membrane rigidification L. pneumophila intracellular replication was significantly reduced. Palmitoleic acid - a C16:1 monounsaturated fatty acid - that promotes membrane disorder when enriched in GPLs significantly increased bacterial replication within human and murine macrophages but not in axenic growth assays. Lipidome analysis of infected macrophages showed that treatment with exogenous palmitoleic acid resulted in membrane acyl chain reprogramming in a manner that promotes membrane disorder and live-cell imaging revealed that the consequences of increasing membrane disorder impinge on several LCV homeostasis parameters. Collectively, we provide experimental evidence that L. pneumophila replication within its intracellular niche is a function of the lipid bilayer disorder and hydrophobic thickness.

Green cabbage supplementation influences the gene expression and fatty acid levels of adipose tissue in Chinese Wanxi White geese

OBJECTIVE

Dietary green cabbage was evaluated for its impact on fatty acid synthetic ability in different adipose tissues during fattening of Wanxi White geese.

METHODS

A total of 256 Wanxi White geese at their 70 days were randomly allocated into 4 groups with 4 replicates and fed 0%, 15%, 30%, and 45% fresh green cabbage (relative to dry matter), respectively, in each group. Adipose tissues (subcutaneous and abdominal fat), liver and blood were collected from 4 birds in each replicate at their 70, 80, 90, and 100 days for fatty acid composition, relative gene expression and serum lipid analysis. Two-way or three-way analysis of variance was used for analysis.

RESULTS

The contents of palmitic acid (C16:0), palmitoleic acid (C16:1), linoleic acid (C18:2), and alpha-linolenic acid (C18:3) were feeding time dependently increased. The C16:0 and stearic acid (C18:0) were higher in abdominal fat, while C16:1, oleic acid (C18:1), and C18:2 were higher in subcutaneous fat. Geese fed 45% green cabbage exhibited highest level of C18:3. Geese fed green cabbage for 30 d exhibited higher level of C16:0 and C18:0 in abdominal fat, while geese fed 30% to 45% green cabbage exhibited higher C18:3 in subcutaneous fat. The expression of Acsl1 (p = 0.003) and Scd1 (p<0.0001) were decreased with green cabbage addition. Interaction between feeding time and adipose tissue affected elongation of long-chain fatty acids family member 6 (Elovl6), acyl-CoA synthetase longchain family member 1 (Acsl1), and stearoly-coA desaturase 1 (Scd1) gene expression levels (p = 0.013, p = 0.003, p = 0.005). Feeding time only affected serum lipid levels of free fatty acid and chylomicron. Higher contents of C16:0, C18:1, and C18:3 were associated with greater mRNA expression of Scd1 (p<0.0001), while higher level of C18:2 was associated with less mRNA expression of Scd1 (p<0.0001).

CONCLUSION

Considering content of C18:2 and C18:3, 30% addition of green cabbage could be considered for fattening for 30 days in Wanxi White geese.

Integrated multi-omics analysis reveals variation in intramuscular fat among muscle locations of Qinchuan cattle

BACKGROUND

Intramuscular fat (IMF) is closely related to the tenderness, marbling, juiciness, and flavor of meat. We used a combined transcriptome and metabolome analysis to investigate the molecular mechanisms underlying phenotypic variation among Qinchuan cattle.

RESULTS

The IMF content was relatively high in the meat of Qinchuan cattle bulls and differed among muscle locations, namely the high rib (15.86%), ribeye (14%), striploin (10.44%), and tenderloin (8.67%). CCDC80 and the HOX gene cluster may regulate intramuscular adipose tissue deposition. Moreover, erucic acid (EA) was found to be the main metabolite in Qinchuan beef cattle, with a high concentration in IMF. The deposition of IMF could be regulated by the metabolic pathway for unsaturated fatty acids involving EA and the ACOX3, HACD2, and SCD5 genes. In addition, differentially expressed genes and metabolites were enriched in three major KEGG pathways: purine metabolism, pyrimidine metabolism, and the metabolism of glycine, serine, and threonine.

CONCLUSIONS

We identified a significant metabolite, EA, with variation in IMF. Its closely related genes, ACOX3, HACD2, and SCD5, co-regulate the metabolism of unsaturated fatty acids, ultimately affecting the accumulation of intramuscular adipose tissue in Qinchuan cattle. Consequently, Qinchuan cattle are an elite cultivar for high-quality beef production and have great potential for breeding.

Molecular Basis of Unequal Alternative Splicing of Human SCD5 and Its Alteration by Natural Genetic Variations

Alternative splicing (AS) is a major means of post-transcriptional control of gene expression, and provides a dynamic versatility of protein isoforms. Cancer-related AS disorders have diagnostic, prognostic and therapeutic values. Changes in the expression and AS of human stearoyl-CoA desaturase-5 (SCD5) are promising specific tumor markers, although the transcript variants (TVs) of the gene have not yet been confirmed. Our in silico, in vitro and in vivo study focuses on the distribution of SCD5 TVs (A and B) in human tissues, the functionality of the relevant splice sites, and their modulation by certain single-nucleotide variations (SNVs). An order of magnitude higher SCD5A expression was found compared with SCD5B. This unequal splicing is attributed to a weaker recognition of the SCD5B-specific splicing acceptor site, based on predictions confirmed by an optimized minigene assay. The pronounced dominance of SCD5A was largely modified (rs1430176385_A, rs1011850309_A) or even inverted (rs1011850309_C) by natural SNVs at the TV-specific splice sites. Our results provide long missing data on the proportion of SCD5 TVs in human tissues and reveal mutation-driven changes in SCD5 AS, potentially affecting tumor-associated reprogramming of lipid metabolism, thus having prognostic significance, which may be utilized for novel and personalized therapeutic approaches.

Role of Stearoyl-CoA Desaturase 1 in Cardiovascular Physiology

Stearoyl-CoA desaturase is a rate-limiting enzyme in the synthesis of monounsaturated fatty acids. Monounsaturated fatty acids limit the toxicity of exogenous saturated fats. Studies have shown that stearoyl-CoA desaturase 1 is involved in the remodeling of cardiac metabolism. The loss of stearoyl-CoA desaturase 1 reduces fatty acid oxidation and increases glucose oxidation in the heart. Such a change is protective under conditions of a high-fat diet, which reduces reactive oxygen species-generating β-oxidation. In contrast, stearoyl-CoA desaturase 1 deficiency predisposes individuals to atherosclerosis under conditions of hyperlipidemia but protects against apnea-induced atherosclerosis. Stearoyl-CoA desaturase 1 deficiency also impairs angiogenesis after myocardial infarction. Clinical data show a positive correlation between blood stearoyl-CoA Δ-9 desaturation rates and cardiovascular disease and mortality. Moreover, stearoyl-CoA desaturase inhibition is considered an attractive intervention in some obesity-associated pathologies, and the importance of stearoyl-CoA desaturase in the cardiovascular system might be a limitation for developing such therapy. This review discusses the role of stearoyl-CoA desaturase 1 in the regulation of cardiovascular homeostasis and the development of heart disease and presents markers of systemic stearoyl-CoA desaturase activity and their predictive potential in the diagnosis of cardiovascular disorders.

SCD5 Regulation by VHL Affects Cell Proliferation and Lipid Homeostasis in ccRCC

Clear cell renal cell carcinoma (ccRCC) is the most common histological subtype of renal cancer, and inactivation of the VHL tumor suppressor gene is found in almost all cases of hereditary and sporadic ccRCCs. CcRCC is associated with the reprogramming of fatty acid metabolism, and stearoyl-CoA desaturases (SCDs) are the main enzymes controlling fatty acid composition in cells. In this study, we report that mRNA and protein expression of the stearoyl-CoA desaturase SCD5 is downregulated in VHL-deficient cell lines. Similarly, in C. elegans vhl-1 mutants, FAT-7/SCD5 activity is repressed, supporting an evolutionary conservation. SCD5 regulation by VHL depends on HIF, and loss of SCD5 promotes cell proliferation and a metabolic shift towards ceramide production. In summary, we identify a novel regulatory function of VHL in relation to SCD5 and fatty acid metabolism, and propose a new mechanism of how loss of VHL may contribute to ccRCC tumor formation and progression.

Potentiation of Lipotoxicity in Human EndoC-βH1 β-Cells by Glucose is Dependent on the Structure of Free Fatty Acids

SCOPE

Lipotoxicity is a significant element in the development of type 2 diabetes mellitus (T2DM). Since pro-diabetic nutritional patterns are associated with hyperglycemia as well as hyperlipidemia, the study analyzes the effects of combining these lipid and carbohydrate components with a special focus on the structural fatty acid properties such as increasing chain length (C16-C20) and degree of saturation with regard to the role of glucolipotoxicity in human EndoC-βH1 β-cells.

METHODS AND RESULTS

β-cell death induced by saturated FFAs is potentiated by high concentrations of glucose in a chain length-dependent manner starting with stearic acid (C18:0), whereas toxicity remains unchanged in the case of monounsaturated FFAs. Interference with FFA desaturation by overexpression and inhibition of stearoyl-CoA-desaturase, which catalyzes the rate-limiting step in the conversion of long-chain saturated into corresponding monounsaturated FFAs, does not affect the potentiating effect of glucose, but FFA desaturation reduces lipotoxicity and plays an important role in the formation of lipid droplets. Crucial elements underlying glucolipotoxicity are ER stress induction and cardiolipin peroxidation in the mitochondria.

CONCLUSION

In the context of nutrition, the data emphasize the importance of the lipid component in glucolipotoxicity related to the development of β-cell dysfunction and death in the manifestation of T2DM.

Cis- and Trans-variations of Stearoyl-CoA Desaturase Provide New Insights into the Mechanisms of Diverged Pattern of Phenotypic Plasticity for Temperature Adaptation in Two Congeneric Oyster Species

The evolution of phenotypic plasticity plays an essential role in adaptive responses to climate change; however, its regulatory mechanisms in marine organisms which exhibit high phenotypic plasticity still remain poorly understood. The temperature-responsive trait oleic acid content and its major gene stearoyl-CoA desaturase (Scd) expression have diverged in two allopatric congeneric oyster species, cold-adapted Crassostrea gigas and warm-adapted Crassostrea angulata. In this study, genetic and molecular methods were used to characterize fatty acid desaturation and membrane fluidity regulated by oyster Scd. Sixteen causative single-nucleotide polymorphisms (SNPs) were identified in the promoter/cis-region of the Scd between wild C. gigas and C. angulata. Further functional experiments showed that an SNP (g.-333C [C. gigas allele] >T [C. angulata allele]) may influence Scd transcription by creating/disrupting the binding motif of the positive trans-factor Y-box factor in C. gigas/C. angulata, which mediates the higher/lower constitutive expression of Scd in C. gigas/C. angulata. Additionally, the positive trans-factor sterol-regulatory element-binding proteins (Srebp) were identified to specifically bind to the promoter of Scd in both species, and were downregulated during cold stress in C. gigas compared to upregulated in C. angulata. This partly explains the relatively lower environmental sensitivity (plasticity) of Scd in C. gigas. This study serves as an experimental case to reveal that both cis- and trans-variations shape the diverged pattern of phenotypic plasticity, which provides new insights into the formation of adaptive traits and the prediction of the adaptive potential of marine organisms to future climate change.

Investigating the role of FADS family members in breast cancer based on bioinformatic analysis and experimental validation

Breast cancer (BC) is the most common malignant tumor in women worldwide. Emerging evidence indicates the significance of fatty acid metabolism in BC. Fatty acid desaturase (FADS) is closely associated with cancer occurrence and development. Here, bioinformatic analysis and experimental validation were applied to investigate the potential functions of FADS in BC. Several public databases, including TCGA, GEO, HPA, Kaplan-Meier plotter, STRING, DAVID, cBioPortal, TIMER, TRRUST, and LinkedOmics were used to determine mRNA/protein expression levels, prognostic significance, functional enrichment, genetic alterations, association with tumor-infiltrating immune cells, and related transcription factors and kinases. BC tissues showed higher and lower mRNA expression of FADS2/6/8 and FADS3/4/5, respectively. FADS1/2/6 and FADS3/4/5 showed higher and lower protein expression levels, respectively, in BC tissues. Moreover, FADS1/7 up- and FADS3/8 down-regulation predicted poor overall and recurrence-free survival, while FADS2/5 up- and FADS4 down-regulation were associated with poor recurrence-free survival. Receiver operating characteristic curves revealed that FADS2/3/4/8 were indicative diagnostic markers. FADS family members showing differential expression levels were associated with various clinical subtypes, clinical stages, lymph node metastasis status, copy number variants, DNA methylation, and miRNA regulation in BC. The mRNA expression level of FADS1/2/3/4/5/7/8 was observed to be significantly negatively correlated with DNA methylation. FADS1/2 upregulation was significantly correlated with clinical stages. FADS1/4 expression was obviously lower in BC patients with higher lymph node metastasis than lower lymph node metastasis, while FADS7/8 expression was obviously higher in BC patients with higher lymph node metastasis than lower lymph node metastasis. FADS family members showed varying degrees of genetic alterations, and Gene Ontology and KEGG pathway enrichment analyses suggested their involvement in lipid metabolism. Their expression level was correlated with immune cell infiltration levels. FADS2 was chosen for further validation analyses. We found FADS2 to be significantly over-expressed in clinical BC tissue samples. The proliferation, migration, and invasion abilities of MDA-MB-231 and BT474 cells were significantly reduced after FADS2 knockdown. Furthermore, FADS2 may promote the occurrence and development of BC cells via regulating the epithelial-mesenchymal transition (EMT) pathway. Altogether, our results suggest that FADS1/2/3/4 can serve as potential therapeutic targets, prognostic indicators, and diagnostic markers in patients with BC.

A mass spectrometry imaging and lipidomic investigation reveals aberrant lipid metabolism in the orthotopic mouse glioma

Lipids perform multiple biological functions and reflect the physiology and pathology of cells, tissues, and organs. Here, we sought to understand lipid content in relation to tumor pathology by characterizing phospholipids and sphingolipids in the orthotopic mouse glioma using MALDI MS imaging (MSI) and LC-MS/MS. Unsupervised clustering analysis of the MALDI-MSI data segmented the coronal tumoral brain section into 10 histopathologically salient regions. Heterogeneous decrease of the common saturated phosphatidylcholines (PCs) in the tumor was accompanied by the increase of analogous PCs with one or two additional fatty acyl double bonds and increased lyso-PCs. Polyunsaturated fatty acyl-PCs and ether PCs highlighted the striatal tumor margins, whereas the distributions of other PCs differentiated the cortical and striatal tumor parenchyma. We detected a reduction of SM d18:1/18:0 and the heterogeneous mild increase of SM d18:1/16:0 in the tumor, whereas ceramides accumulated only in a small patch deep in the tumoral parenchyma. LC-MS/MS analyses of phospholipids and sphingolipids complemented the MALDI-MSI observation, providing a snapshot of these lipids in the tumor. Finally, the proposed mechanisms responsible for the tumoral lipid changes were contrasted with our interrogation of gene expression in human glioma. Together, these lipidomic results unveil the aberrant and heterogeneous lipid metabolism in mouse glioma where multiple lipid-associated signaling pathways underline the tumor features, promote the survival, growth, proliferation, and invasion of different tumor cell populations, and implicate the management strategy of a multiple-target approach for glioma and related brain malignancies.

A Single Nucleotide Polymorphism (rs3811792) Affecting Human SCD5 Promoter Activity Is Associated with Diabetes Mellitus

The combined prevalence of type 1 (T1DM) and type 2 (T2DM) diabetes mellitus is 10.5% worldwide and this is constantly increasing. The pathophysiology of the diseases include disturbances of the lipid metabolism, in which acyl-CoA desaturases play a central role as they synthesize unsaturated fatty acids, thereby providing protection against lipotoxicity. The stearoyl-CoA desaturase-5 (SCD5) isoform has received little scientific attention. We aimed to investigate the SCD5 promoter and its polymorphisms in vitro, in silico and in a case-control study. The SCD5 promoter region was determined by a luciferase reporter system in HepG2, HEK293T and SK-N-FI cells and it was proved to be cell type-specific, but it was insensitive to different fatty acids. The effect of the SCD5 promoter polymorphisms rs6841081 and rs3811792 was tested in the transfected cells. The T allele of rs3811792 single nucleotide polymorphism (SNP) significantly reduced the activity of the SCD5 promoter in vitro and modified several transcription factor binding sites in silico. A statistically significant association of rs3811792 SNP with T1DM and T2DM was also found, thus supporting the medical relevance of this variation and the complexity of the molecular mechanisms in the development of metabolic disorders. In conclusion, the minor allele of rs3811792 polymorphism might contribute to the development of diabetes by influencing the SCD5 promoter activity.

Lipid metabolism in pancreatic cancer: emerging roles and potential targets

Pancreatic cancer is one of the most serious health issues in developed and developing countries, with a 5-year overall survival rate currently <9%. Patients typically present with advanced disease due to vague symptoms or lack of screening for early cancer detection. Surgical resection represents the only chance for cure, but treatment options are limited for advanced diseases, such as distant metastatic or locally progressive tumors. Although adjuvant chemotherapy has improved long-term outcomes in advanced cancer patients, its response rate is low. So, exploring other new treatments is urgent. In recent years, increasing evidence has shown that lipid metabolism can support tumorigenesis and disease progression as well as treatment resistance through enhanced lipid synthesis, storage, and catabolism. Therefore, a better understanding of lipid metabolism networks may provide novel and promising strategies for early diagnosis, prognosis estimation, and targeted therapy for pancreatic cancer patients. In this review, we first enumerate and discuss current knowledge about the advances made in understanding the regulation of lipid metabolism in pancreatic cancer. In addition, we summarize preclinical studies and clinical trials with drugs targeting lipid metabolic systems in pancreatic cancer. Finally, we highlight the challenges and opportunities for targeting lipid metabolism pathways through precision therapies in pancreatic cancer.

Chromatin conformation of human oral epithelium can identify orofacial cleft missing functional variants

Genome-wide association studies (GWASs) are the most widely used method to identify genetic risk loci associated with orofacial clefts (OFC). However, despite the increasing size of cohort, GWASs are still insufficient to detect all the heritability, suggesting there are more associations under the current stringent statistical threshold. In this study, we obtained an integrated epigenomic dataset based on the chromatin conformation of a human oral epithelial cell line (HIOEC) using RNA-seq, ATAC-seq, H3K27ac ChIP-seq, and DLO Hi-C. Presumably, this epigenomic dataset could reveal the missing functional variants located in the oral epithelial cell active enhancers/promoters along with their risk target genes, despite relatively less-stringent statistical association with OFC. Taken a non-syndromic cleft palate only (NSCPO) GWAS data of the Chinese Han population as an example, 3664 SNPs that cannot reach the strict significance threshold were subjected to this functional identification pipeline. In total, 254 potential risk SNPs residing in active cis-regulatory elements interacting with 1 718 promoters of oral epithelium-expressed genes were screened. Gapped k-mer machine learning based on enhancers interacting with epithelium-expressed genes along with in vivo and in vitro reporter assays were employed as functional validation. Among all the potential SNPs, we chose and confirmed that the risk alleles of rs560789 and rs174570 reduced the epithelial-specific enhancer activity by preventing the binding of transcription factors related to epithelial development. In summary, we established chromatin conformation datasets of human oral epithelial cells and provided a framework for testing and understanding how regulatory variants impart risk for clefts.

Differential gene expression profiling reveals potential biomarkers and pharmacological compounds against SARS-CoV-2: Insights from machine learning and bioinformatics approaches

The COVID-19 pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has created an urgent global situation. Therefore, it is necessary to identify the differentially expressed genes (DEGs) in COVID-19 patients to understand disease pathogenesis and the genetic factor(s) responsible for inter-individual variability and disease comorbidities. The pandemic continues to spread worldwide, despite intense efforts to develop multiple vaccines and therapeutic options against COVID-19. However, the precise role of SARS-CoV-2 in the pathophysiology of the nasopharyngeal tract (NT) is still unfathomable. This study utilized machine learning approaches to analyze 22 RNA-seq data from COVID-19 patients (n = 8), recovered individuals (n = 7), and healthy individuals (n = 7) to find disease-related differentially expressed genes (DEGs). We compared dysregulated DEGs to detect critical pathways and gene ontology (GO) connected to COVID-19 comorbidities. We found 1960 and 153 DEG signatures in COVID-19 patients and recovered individuals compared to healthy controls. In COVID-19 patients, the DEG–miRNA, and DEG–transcription factors (TFs) interactions network analysis revealed that E2F1, MAX, EGR1, YY1, and SRF were the highly expressed TFs, whereas hsa-miR-19b, hsa-miR-495, hsa-miR-340, hsa-miR-101, and hsa-miR-19a were the overexpressed miRNAs. Three chemical agents (Valproic Acid, Alfatoxin B1, and Cyclosporine) were abundant in COVID-19 patients and recovered individuals. Mental retardation, mental deficit, intellectual disability, muscle hypotonia, micrognathism, and cleft palate were the significant diseases associated with COVID-19 by sharing DEGs. Finally, the detected DEGs mediated by TFs and miRNA expression indicated that SARS-CoV-2 infection might contribute to various comorbidities. Our results provide the common DEGs between COVID-19 patients and recovered humans, which suggests some crucial insights into the complex interplay between COVID-19 progression and the recovery stage, and offer some suggestions on therapeutic target identification in COVID-19 caused by the SARS-CoV-2.

Acylcarnitines: Nomenclature, Biomarkers, Therapeutic Potential, Drug Targets, and Clinical Trials

Acylcarnitines are fatty acid metabolites that play important roles in many cellular energy metabolism pathways. They have historically been used as important diagnostic markers for inborn errors of fatty acid oxidation and are being intensively studied as markers of energy metabolism, deficits in mitochondrial and peroxisomal β -oxidation activity, insulin resistance, and physical activity. Acylcarnitines are increasingly being identified as important indicators in metabolic studies of many diseases, including metabolic disorders, cardiovascular diseases, diabetes, depression, neurologic disorders, and certain cancers. The US Food and Drug Administration-approved drug L-carnitine, along with short-chain acylcarnitines (acetylcarnitine and propionylcarnitine), is now widely used as a dietary supplement. In light of their growing importance, we have undertaken an extensive review of acylcarnitines and provided a detailed description of their identity, nomenclature, classification, biochemistry, pathophysiology, supplementary use, potential drug targets, and clinical trials. We also summarize these updates in the Human Metabolome Database, which now includes information on the structures, chemical formulae, chemical/spectral properties, descriptions, and pathways for 1240 acylcarnitines. This work lays a solid foundation for identifying, characterizing, and understanding acylcarnitines in human biosamples. We also discuss the emerging opportunities for using acylcarnitines as biomarkers and as dietary interventions or supplements for many wide-ranging indications. The opportunity to identify new drug targets involved in controlling acylcarnitine levels is also discussed. SIGNIFICANCE STATEMENT: This review provides a comprehensive overview of acylcarnitines, including their nomenclature, structure and biochemistry, and use as disease biomarkers and pharmaceutical agents. We present updated information contained in the Human Metabolome Database website as well as substantial mapping of the known biochemical pathways associated with acylcarnitines, thereby providing a strong foundation for further clarification of their physiological roles.

Molecular Mechanisms Underlying the Elevated Expression of a Potentially Type 2 Diabetes Mellitus Associated SCD1 Variant

Disturbances in lipid metabolism related to excessive food intake and sedentary lifestyle are among major risk of various metabolic disorders. Stearoyl-CoA desaturase-1 (SCD1) has an essential role in these diseases, as it catalyzes the synthesis of unsaturated fatty acids, both supplying for fat storage and contributing to cellular defense against saturated fatty acid toxicity. Recent studies show that increased activity or over-expression of SCD1 is one of the contributing factors for type 2 diabetes mellitus (T2DM). We aimed to investigate the impact of the common missense rs2234970 (M224L) polymorphism on SCD1 function in transfected cells. We found a higher expression of the minor Leu224 variant, which can be attributed to a combination of mRNA and protein stabilization. The latter was further enhanced by various fatty acids. The increased level of Leu224 variant resulted in an elevated unsaturated: saturated fatty acid ratio, due to higher oleate and palmitoleate contents. Accumulation of Leu224 variant was found in a T2DM patient group, however, the difference was statistically not significant. In conclusion, the minor variant of rs2234970 polymorphism might contribute to the development of obesity-related metabolic disorders, including T2DM, through an increased intracellular level of SCD1.

Transcriptomic profile of longissimus thoracis associated with fatty acid content in Nellore beef cattle

The beef fatty acid (FA) profile has the potential to impact human health, and displays polygenic and complex features. This study aimed to identify the transcriptomic FA profile in the longissimus thoracis muscle in Nellore beef cattle finished in feedlot. Forty-four young bulls were sampled to assess the beef FA profile by considering 14 phenotypes and including differentially expressed genes (DEG), co-expressed (COE), and differentially co-expressed genes (DCO) analyses. All samples (n = 44) were used for COE analysis, whereas 30 samples with extreme phenotypes for the beef FA profile were used for DEG and DCO. A total of 912 DEG were identified, and the polyunsaturated (n = 563) and unsaturated ω-3 (n = 346) FA sums groups were the most frequently observed. The COE analyses identified three modules, of which the blue module (n = 1776) was correlated with eight of 14 FA phenotypes. Also, 759 DCO genes were listed, and the oleic acid (n = 358) and monounsaturated fatty acids sum (n = 120) were the most frequent. Furthermore, 243 and 13, 319 and seven, and 173 and 12 gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways were enriched respectively for the DEG, COE, and DCO analyses. Combining the results, we highlight the unexplored GIPC2, ASB5, and PPP5C genes in cattle. Besides LIPE and INSIG2 genes in COE modules, the ACSL3, ECI1, DECR2, FITM1, and SDHB genes were signaled in at least two analyses. These findings contribute to understand the genetic mechanisms underlying the beef FA profile in Nellore beef cattle finished in feedlot.

Identification of Scd5 as a functional regulator of visceral fat deposition and distribution

Ectopic deposition of visceral adipose tissue (VAT) in abdomen is usually accompanied with systematic chaos of energy metabolism, a higher risk of cardiovascular diseases and type II diabetes. Here, we identified a previously unexplored gene Scd5 as a master regulator of fat distribution, which alone plays a significant role in determining the VAT accumulation. Firstly, zebrafish scd5 had the highest homology with human SCD5 compared to other SCDs in mouse and rat. We then observed that scd5-homozygous mutant zebrafish displayed a puffy, short and rounded apple-shaped figure. Whole-mount micro-CT scan showed that excessive VAT deposition and short spine are responsible for the abnormal body ratio. And the supplementation of ω3-polyunsaturated fatty acid (ω3-PUFA) in dietary significantly decreased VAT accumulation in scd5^−/− zebrafish. Lastly, transcriptional analyses revealed that the Wnt, PPAR, C/EBP, and fat synthesis signaling pathways are significantly affected in the VAT of scd5^−/− mutant and restored by ω3-PUFA.

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Zebrafish scd5 is a better match of homolog to human SCD5

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scd5 deficiency induced significant VAT depositions in zebrafish

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Supplementation of ω3-PUFA significantly reduced the VAT deposition in scd5 mutants

Deep Profiling of Aminophospholipids Reveals a Dysregulated Desaturation Pattern in Breast Cancer Cell Lines

Phosphatidylethanolamines (PEs), ether-PEs, and phosphatidylserines (PSs) are glycerophospholipids harboring a primary amino group in their headgroups. They are key components of mammalian cell membranes and play pivotal roles in cell signaling and apoptosis. In this study, a liquid chromatography-mass spectrometry (LC-MS) workflow for deep profiling of PEs, ether-PEs, and PSs has been developed by integrating two orthogonal derivatizations: (1) derivatization of the primary amino group by 4-trimethylammoniumbutyryl-N-hydroxysuccinimide (TMAB-NHS) for enhanced LC separation and MS detection and (2) the Paternò-Büchi (PB) reaction for carbon-carbon double bond (C═C) derivatization and localization. Significant improvement of the limit of identification down to the C═C location has been achieved for the standards of PSs (3 nM) and ether-PEs (20 nM). This workflow facilitates an identification of more than 200 molecular species of aminophospholipids in the porcine brain, two times more than those identified without TMAB-NHS derivatization. Importantly, we discovered that the n-10 isomers in C16:1 and C18:1 of aminophospholipids showed elevated contribution among other isomers, which correlated well with an increased transcription of the corresponding desaturase (FADS2) in the human breast cancer cell line (MDA-MB-231) relative to that in the normal cell line (HMEC). The abovementioned data suggest that lipid reprograming via forming different C═C location isomers might be an alternative mechanism in cancer cells.

IL-19 Contributes to the Development of Nonalcoholic Steatohepatitis by Altering Lipid Metabolism

Interleukin (IL)-19, a member of the IL-10 family, is an anti-inflammatory cytokine produced primarily by macrophages. Nonalcoholic steatohepatitis (NASH) is a disease that has progressed from nonalcoholic fatty liver disease (NAFLD) and is characterized by inflammation and fibrosis. We evaluated the functions of IL-19 in a NAFLD/NASH mouse model using a 60% high fat diet with 0.1% methionine, without choline, and with 2% cholesterol (CDAHFD). Wild-type (WT) and IL-19 gene-deficient (KO) mice were fed a CDAHFD or standard diet for 9 weeks. Liver injury, inflammation, and fibrosis induced by CDAHFD were significantly worse in IL-19 KO mice than in WT mice. IL-6, TNF-α, and TGF-β were significantly higher in IL-19 KO mice than in WT mice. As a mechanism using an in vitro experiment, palmitate-induced triglyceride and cholesterol contents were decreased by the addition of IL-19 in HepG2 cells. Furthermore, addition of IL-19 decreased the expression of fatty acid synthesis-related enzymes and increased ATP content in HepG2 cells. The action of IL-19 in vitro suppressed lipid metabolism. In conclusion, IL-19 may play an important role in the development of steatosis and fibrosis by directly regulating liver metabolism and may be a potential target for the treatment of liver diseases.

Cloning and characterisation of a Δ9 fatty acyl desaturase-like gene from the red claw crayfish (Cherax quadricarinatus) and its expression analysis under cold stress

Desaturase is one of the key enzymes in the unsaturated fatty acid synthesis pathway. Δ9 desaturase catalyzes the synthesis of oleic acid from stearic acid by introducing double bonds in the 9th and 10th carbon chains, thereby increasing the content of MUFAs in the body. In order to explore the main function of the Δ9 desaturase gene under low temperature stress, RACE-PCR technology was used in this study to clone the full-length sequence of the CqFAD9-like from the hepatopancreas of red claw crayfish, Cherax quadricarinatus. The full length of the sequence is 1236 bp, and the open reading frame is 1041 bp, encoding 346 amino acid residues. The 5 'UTR is 116 bp, the 3' UTR is 79 bp, and the 3 'UTR contains a PloyA tail. The predicted theoretical isoelectric point and molecular weight are 8.68 and 40.28 kDa, respectively. Homology analysis showed that the sequence had the highest similarity with FAD9 from crustaceans. The results of real-time PCR showed that the expression level of this gene was highest in the hepatopancreas, which was significantly higher than other tissues, followed by the ovaries, brain ganglion and stomach. At the same time, the expression of the CqFAD9-like in hepatopancreas of crayfish cultured at 25, 20, 15 and 9 °C for four weeks was detected. The results showed that expression of the FAD9 gene increased gradually with decreasing temperature, indicating that metabolic desaturation might play a regulatory role during cold stress.

Prostate Cancer Progression: as a Matter of Fats

Advanced prostate cancer (PCa) represents the fifth cause of cancer death worldwide. Although survival has improved with second-generation androgen signaling and Parp inhibitors, the benefits are not long-lasting, and new therapeutic approaches are sorely needed. Lipids and their metabolism have recently reached the spotlight with accumulating evidence for their role as promoters of PCa development, progression, and metastasis. As a result, interest in targeting enzymes/transporters involved in lipid metabolism is rapidly growing. Moreover, the use of lipogenic signatures to predict prognosis and resistance to therapy has been recently explored with promising results. Despite the well-known association between obesity with PCa lethality, the underlying mechanistic role of diet/obesity-derived metabolites has only lately been unveiled. Furthermore, the role of lipids as energy source, building blocks, and signaling molecules in cancer cells has now been revisited and expanded in the context of the tumor microenvironment (TME), which is heavily influenced by the external environment and nutrient availability. Here, we describe how lipids, their enzymes, transporters, and modulators can promote PCa development and progression, and we emphasize the role of lipids in shaping TME. In a therapeutic perspective, we describe the ongoing efforts in targeting lipogenic hubs. Finally, we highlight studies supporting dietary modulation in the adjuvant setting with the purpose of achieving greater efficacy of the standard of care and of synthetic lethality. PCa progression is "a matter of fats", and the more we understand about the role of lipids as key players in this process, the better we can develop approaches to counteract their tumor promoter activity while preserving their beneficial properties.

Monounsaturated Fatty Acids in Obesity-Related Inflammation

Obesity is an important aspect of the metabolic syndrome and is often associated with chronic inflammation. In this context, inflammation of organs participating in energy homeostasis (such as liver, adipose tissue, muscle and pancreas) leads to the recruitment and activation of macrophages, which secrete pro-inflammatory cytokines. Interleukin-1β secretion, sustained C-reactive protein plasma levels and activation of the NLRP3 inflammasome characterize this inflammation. The Stearoyl-CoA desaturase-1 (SCD1) enzyme is a central regulator of lipid metabolism and fat storage. This enzyme catalyzes the generation of monounsaturated fatty acids (MUFAs)-major components of triglycerides stored in lipid droplets-from saturated fatty acid (SFA) substrates. In this review, we describe the molecular effects of specific classes of fatty acids (saturated and unsaturated) to better understand the impact of different diets (Western versus Mediterranean) on inflammation in a metabolic context. Given the beneficial effects of a MUFA-rich Mediterranean diet, we also present the most recent data on the role of SCD1 activity in the modulation of SFA-induced chronic inflammation.