Cytoplasmic SIRT6-mediated ACSL5 deacetylation impedes nonalcoholic fatty liver disease by facilitating hepatic fatty acid oxidation.

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive hepatic lipid accumulation, which can progress to nonalcoholic steatohepatitis (NASH). Histone deacetylase Sirtuin 6 (SIRT6) regulates NAFLD by regulating metabolism-related gene expression, but an extrachromosomal role for SIRT6 in NAFLD development remains elusive. We investigated whether SIRT6 functions on NAFLD in the cytoplasm. We found that SIRT6 binds saturated fatty acids, especially palmitic acid. This binding leads to its nuclear export, where it deacetylates long-chain acyl-CoA synthase 5 (ACSL5), thereby facilitating fatty acid oxidation. High-fat diet-induced NAFLD is suppressed by ACSL5 hepatic overexpression but is exacerbated by its depletion. As confirmation, overexpression of a deacetylated ACSL5 mimic attenuated NAFLD in Sirt6 liver-specific knockout mice. Moreover, NASH-hepatic tissues from both patients and diet-fed mice exhibited significantly reduced cytoplasmic SIRT6 levels and increased ACSL5 acetylation. The SIRT6/ACSL5 signaling pathway has a critical role in NAFLD progression and might constitute an avenue for therapeutic intervention.

Deficiency of acyl-CoA synthetase 5 is associated with a severe and treatable failure to thrive of neonatal onset.

Failure to thrive (FTT) causes significant morbidity, often without clear etiologies. Six individuals of a large consanguineous family presented in the neonatal period with recurrent vomiting and diarrhea, leading to severe FTT. Standard diagnostic work up did not ascertain an etiology. Autozygosity mapping and whole exome sequencing identified homozygosity for a novel genetic variant of the long chain fatty acyl-CoA synthetase 5 (ACSL5) shared among the affected individuals (NM_203379.1:c.1358C>A:p.(Thr453Lys)). Autosomal recessive genotype-phenotype segregation was confirmed by Sanger sequencing. Functional in vitro analysis of the ACSL5 variant by immunofluorescence, western blotting and enzyme assay suggested that Thr453Lys is a loss-of-function mutation without any remaining activity. ACSL5 belongs to an essential enzyme family required for lipid metabolism and is known to contribute the major activity in the mouse intestine. Based on the function of ACSL5 in intestinal long chain fatty acid metabolism and the gastroenterological symptoms, affected individuals were treated with total parenteral nutrition or medium-chain triglyceride-based formula restricted in long-chain triglycerides. The patients responded well and follow up suggests that treatment is only required during early life.

Roles of acyl-CoA synthetase long-chain family member 5 and colony stimulating factor 2 in inhibition of palmitic or stearic acids in lung cancer cell proliferation and metabolism.

Lung cancer is a heterogeneous and complex disease with the highest incidence and mortality rate. The present study aims at defining the lung cancer phenome specificity of lipidomic profiles, screening target lipid-dependent transcriptional alternations, identifying target lipid-associated target genes, and exploring molecular mechanisms. Lung cancer-specific and lung cancer subtype-specific target lipids palmitic acid (C16:0) and stearic acid (C18:0) were found as target lipids by integrating clinical phenomics, lipidomics, and transcriptomics and exhibited antiproliferative effects in sensitive cells. The metabolism-associated gene ACSL5 or inflammation-associated gene CCL3 was identified in lung adenocarcinoma or small lung cancer cells, respectively. C16:0 or C18:0 could upregulate ACSL5 or CSF2 expression in a time- and dose-dependent pattern, and the deletion of both genes led to the insensitivity of cells. Target lipids increased the expression of PDK4 gene in different patterns and inhibited cell proliferation through alterations of intracellular energy. Thus, our data provide a new strategy to investigate the trans-points between clinical and phenomics and lipidomics and target lipid-associated molecular mechanisms to benefit from the discovery of new therapies.

ONECUT2 upregulation is associated with CpG hypomethylation at promoter-proximal DNA in gastric cancer and triggers ACSL5.

Many studies have focused on global hypomethylation or hypermethylation of tumor suppressor genes, but less is known about the impact of promoter hypomethylation of oncogenes. We previously showed that promoter methylation may gradually increase or decrease during the transition from gastric mucosa (GM) to intestinal metaplasia (IM) to gastric cancer (GC). In our study, we focused on regional CpG hypomethylation of the promoter-proximal DNA of the transcription factor ONECUT2 (OC2) in IM and GC cells. We validated the hypomethylation of promoter-proximal DNA of OC2 in 160 primary GCs, in which methylation level correlated negatively with OC2 mRNA level. IM and GC cells stained positively for OC2, whereas GM cells did not. Stable transfection of OC2 in GC cells promoted colony formation, cell migration, invasion and proliferation. Moreover, OC2 knockdown with a short hairpin RNA suppressed tumorigenesis in nude mice. In addition, chromatin immunoprecipitation coupled with DNA sequencing and RNA-seq analyses revealed that OC2 triggered ACSL5, which is strongly expressed in IM of the stomach but not in GM, indicating that OC2 and ACSL5 are early-stage biomarkers for GC. We also observed a high correlation between the levels of OC2 and ACSL5 mRNAs in the GENT database These results suggest that epigenetic alteration of OC2 upregulates its expression, which then activates ACSL5; thus, OC2 is induced in IM by epigenetic alteration and triggers ACSL5 expression, and thus OC2 and ACSL5 may cooperatively promote intestinal differentiation and GC progression.

Targeting Long Chain Acyl-CoA Synthetases for Cancer Therapy.

The deregulation of cancer cell metabolic networks is now recognized as one of the hallmarks of cancer. Abnormal lipid synthesis and extracellular lipid uptake are advantageous modifications fueling the needs of uncontrolled cancer cell proliferation. Fatty acids are placed at the crossroads of anabolic and catabolic pathways, as they are implicated in the synthesis of phospholipids and triacylglycerols, or they can undergo ß-oxidation. Key players to these decisions are the long-chain acyl-CoA synthetases, which are enzymes that catalyze the activation of long-chain fatty acids of 12-22 carbons. Importantly, the long-chain acyl-CoA synthetases are deregulated in many types of tumors, providing a rationale for anti-tumor therapeutic opportunities. The purpose of this review is to summarize the last up-to-date findings regarding their role in cancer, and to discuss the related emerging tumor targeting opportunities.

Expression Analysis of ACSL5 and Wnt2B in Human Congenital Pulmonary Airway Malformations.

BACKGROUND: The objective of this study was to determine acyl-CoA synthetase 5 (ACSL5) and Wnt2B expression patterns in human congenital pulmonary airway malformations (CPAMs) and to identify the possible roles of ACSL5 and Wnt2B in the pathogenesis of CPAM. METHODS: Expression of ACSL5 and Wnt2B was evaluated by immunohistochemical staining, Western blotting, and quantitative real-time polymerase chain reaction, which were performed on surgical specimens of CPAM and adjacent normal lung tissues as controls. RESULTS: Immunohistochemistry revealed that ACSL5 and Wnt2B immunopositive cells were predominantly detected in the mesenchymal cell nucleus, and there were lower expressions of ACSL5 and Wnt2B immunopositive cells in CPAM tissues than those in adjacent normal lung tissues. Western blotting and quantitative real-time polymerase chain reaction showed that ACSL5 and Wnt2B protein and mRNA expressions were significantly decreased in CPAM tissues as compared to the adjacent normal lung tissues (P < 0.05). In addition, there was a reduced level of ACSL5 relative to that of Wnt2B. CONCLUSIONS: The decreased ACSL5 and Wnt2B expressions correlated with aberrations in pulmonary development and in the pathogenesis of CPAM, so downregulation of ACSL5 and Wnt2B could play an important role in the development of bronchial-alveolar structures in CPAM.

The type 2 diabetes presumed causal variant within TCF7L2 resides in an element that controls the expression of ACSL5.

AIMS/HYPOTHESIS: One of the most strongly associated type 2 diabetes loci reported to date resides within the TCF7L2 gene. Previous studies point to the T allele of rs7903146 in intron 3 as the causal variant at this locus. We aimed to identify the actual gene(s) under the influence of this variant. METHODS: Using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 nuclease, we generated a 1.4 kb deletion of the genomic region harbouring rs7903146 in the HCT116 cell line, followed by global gene expression analysis. We then carried out a combination of circularised chromosome conformation capture (4C) and Capture C in cell lines, HCT116 and NCM460 in order to ascertain which promoters of these perturbed genes made consistent physical contact with this genomic region. RESULTS: We observed 99 genes with significant differential expression (false discovery rate [FDR] cut-off:10%) and an effect size of at least twofold. The subsequent promoter contact analyses revealed just one gene, ACSL5, which resides in the same topologically associating domain as TCF7L2. The generation of additional, smaller deletions (66 bp and 104 bp) comprising rs7903146 showed consistently reduced ACSL5 mRNA levels across all three deletions of up to 30-fold, with commensurate loss of acyl-CoA synthetase long-chain family member 5 (ACSL5) protein. Notably, the deletion of this single-nucleotide polymorphism region abolished significantly detectable chromatin contacts with the ACSL5 promoter. We went on to confirm that contacts between rs7903146 and the ACSL5 promoter regions were conserved in human colon tissue. ACSL5 encodes ACSL5, an enzyme with known roles in fatty acid metabolism. CONCLUSIONS/INTERPRETATION: This 'variant to gene mapping' effort implicates the genomic location harbouring rs7903146 as a regulatory region for ACSL5.

Deciphering fatty acid biosynthesis-driven molecular subtypes in pancreatic ductal adenocarcinoma with prognostic insights.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) poses a significant challenge due to its high heterogeneity and aggressiveness. Recognizing the urgency to delineate molecular subtypes, our study focused on the emerging field of lipid metabolism remodeling in PDAC, particularly exploring the prognostic potential and molecular classification associated with fatty acid biosynthesis. METHODS: Gene set variation analysis (GSVA) and single-sample gene set enrichment analysis (ssGSEA) were performed to evaluate the dysregulation of lipid metabolism in PDAC. Univariate cox analysis and the LASSO module were used to build a prognostic risk score signature. The distinction of gene expression in different risk groups was explored by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and Weighted Gene Co-expression Network Analysis (WGCNA). The biological function of Acyl-CoA Synthetase Long Chain Family Member 5 (ACSL5), a pivotal gene within 7-hub gene signature panel, was validated through in vitro assays. RESULTS: Our study identified a 7-hub gene signature associated with fatty acid biosynthesis-related genes (FRGs), providing a robust tool for prognosis prediction. The high-FRGs score group displayed a poorer prognosis, decreased immune cell infiltration, and a higher tumor mutation burden. Interestingly, this group exhibited enhanced responsiveness to various compounds according to the Genomics of Drug Sensitivity in Cancer (GDSC) database. Notably, ACSL5 was upregulated in PDAC and essential for tumor progression. CONCLUSION: In conclusion, our research defined two novel fatty acid biosynthesis-based subtypes in PDAC, characterized by distinct transcriptional profiles. These subtypes not only served as prognostic indicator, but also offered valuable insights into their metastatic propensity and therapeutic potential.

Development of fatty acid metabolism score based on gene signature for predicting prognosis and immunotherapy response in colon cancer.

PURPOSE: Metabolic reprogramming is a novel hallmark and therapeutic target of cancer. Our study aimed to establish fatty acid metabolism-associated scores based on gene signature and investigated its effects on immunotherapy in colon cancer. METHODS: Gene expression and clinical information were collected from Gene Expression Omnibus (GEO) database to identify a gene signature by non-negative matrix factorization (NMF) clustering and Cox regression analysis. Subsequently, we constructed the fatty acid metabolism score (FA-score) model by principal component analysis (PCA) and explored its relativity of prognosis and the response to immunotherapy in colon cancer. Finally, the Cancer Genome Atlas (TCGA) database was introduced and in vitro study was performed for verification. RESULTS: The FA-score-high group had a higher level of fatty acid metabolism and was associated with worse patient overall survival. Significantly, FA-score correlated closely with the biomarkers of immunotherapy, and the FA-score-high group had a poorer therapeutic efficacy of immune checkpoint blockade. In vitro experiments demonstrated that ACSL5 may be a critical metabolic regulatory target. CONCLUSIONS: Our study provided a comprehensive analysis of the heterogeneity of fatty acid metabolism in colon cancer. We highlighted the potential clinical utility of fatty acid metabolism-related genes to be biomarkers of colon cancer prognosis and targets to improve the effect of immunotherapy.

Dietary elaidic acid boosts tumoral antigen presentation and cancer immunity via ACSL5.

Immunomodulatory effects of long-chain fatty acids (LCFAs) and their activating enzyme, acyl-coenzyme A (CoA) synthetase long-chain family (ACSL), in the tumor microenvironment remain largely unknown. Here, we find that ACSL5 functions as an immune-dependent tumor suppressor. ACSL5 expression sensitizes tumors to PD-1 blockade therapy in vivo and the cytotoxicity mediated by CD8+ T cells in vitro via regulation of major histocompatibility complex class I (MHC-I)-mediated antigen presentation. Through screening potential substrates for ACSL5, we further identify that elaidic acid (EA), a trans LCFA that has long been considered harmful to human health, phenocopies to enhance MHC-I expression. EA supplementation can suppress tumor growth and sensitize PD-1 blockade therapy. Clinically, ACSL5 expression is positively associated with improved survival in patients with lung cancer, and plasma EA level is also predictive for immunotherapy efficiency. Our findings provide a foundation for enhancing immunotherapy through either targeting ACSL5 or metabolic reprogramming of antigen presentation via dietary EA supplementation.

FABP3 and brown adipocyte-characteristic mitochondrial fatty acid oxidation enzymes are induced in beige cells in a different pathway from UCP1.

Cold exposure and ß3-adrenergic receptor agonist (CL316,243) treatment induce the production of beige cells, which express brown adipocytes(BA)-specific UCP1 protein, in white adipose tissue (WAT). It remains unclear whether the beige cells, which have different gene expression patterns from BA, express BA-characteristic fatty acid oxidation (FAO) proteins. Here we found that 5 day cold exposure and CL316,243 treatment of WAT, but not CL316,243 treatment of primary adipocytes of C57BL/6J mice, increased mRNA levels of BA-characteristic FAO proteins. These results suggest that BA-characteristic FAO proteins are induced in beige cells in a different pathway from UCP1.

Lysophosphatidylcholine inhibits lung cancer cell proliferation by regulating fatty acid metabolism enzyme long-chain acyl-coenzyme A synthase 5.

Lung cancer is a widespread malignancy with a high death rate and disorder of lipid metabolism. Lysophosphatidylcholine (lysoPC) has anti-tumour effects, although the underlying mechanism is not entirely known. The purpose of this study aims at defining changes in lysoPC in lung cancer patients, the effects of lysoPC on lung cancer cells and molecular mechanisms. Lung cancer cell sensitivity to lysoPC was evaluated and decisive roles of long-chain acyl-coenzyme A synthase 5 (ACSL5) in lysoPC regulation were defined by comprehensively evaluating transcriptomic changes of ACSL5-downregulated epithelia. ACSL5 over-expressed in ciliated, club and Goblet cells in lung cancer patients, different from other lung diseases. LysoPC inhibited lung cancer cell proliferation, by inducing mitochondrial dysfunction, altering lipid metabolisms, increasing fatty acid oxidation and reprograming ACSL5/phosphoinositide 3-kinase/extracellular signal-regulated kinase-regulated triacylglycerol-lysoPC balance. Thus, this study provides a general new basis for the discovery of reprogramming metabolisms and metabolites as a new strategy of lung cancer precision medicine.

Role of ACSL5 in fatty acid metabolism.

Free fatty acids (FFAs) are essential energy sources for most body tissues. A fatty acid must be converted to fatty acyl-CoA to oxidize or be incorporated into new lipids. Acyl-CoA synthetase long-chain family member 5 (ACSL5) is localized in the endoplasmic reticulum and mitochondrial outer membrane, where it catalyzes the formation of fatty acyl-CoAs from long-chain fatty acids (C16-C20). Fatty acyl-CoAs are then used in lipid synthesis or ß-oxidation mediated pathways. ACSL5 plays a pleiotropic role in lipid metabolism depending on substrate preferences, subcellular localization and tissue specificity. Here, we review the role of ACSL5 in fatty acid metabolism in multiple metabolic tissues, including the liver, small intestine, adipose tissue, and skeletal muscle. Given the increasing number of studies suggesting the role of ACSL5 in glucose and lipid metabolism, we also summarized the effects of ACSL5 on circulating lipids and insulin resistance.

ACYL-CoA synthetase long-chain 5 polymorphism is associated with weight loss and metabolic changes in response to a partial meal-replacement hypocaloric diet.

INTRODUCTION: Aims:to analyze the effects of the rs2419621 genetic variant of the ACSL5 gene on weight change and metabolic parameters after a partial meal-replacement hypocaloric diet. Methods: this was a non-randomized, single-treatment study with a formula-diet in 44 obese subjects with body mass index (BMI) greater than 35 kg/m2. Patients received nutritional education and a modified diet with two intakes of a normocaloric hyperproteic formula during 3 months. Anthropometric parameters and biochemical profile were measured at baseline and after 3 months. The rs2419621 variant of the ACSL5 gene was assessed using real-time polymerase chain reaction. Results: T-allele carriers showed greater improvement in body weight (CC vs. CT + TT; -7.4 ± 2.1 kg vs. -9.3 ± 1.8 kg; p = 0.01), body mass index (-3.1 ± 0.4 kg/m2 vs. -3.4 ± 0.5 kg/m2; p = 0.02), fat mass (-5.2 ± 1.4 kg vs. -6.4 ± 1.2 kg; p = 0.01) and waist circumference (-6.1 ± 1.1 cm vs. -8.6 ± 0.8 cm; p = 0.02) than non-T-allele carriers. Only subjects with the T allele showed significant improvement in triglyceride levels (-4.6 ± 2.4 md/dL vs. -14.4 ± 2.3 mg/dL; p = 0.01). Finally, improvements in insulin (-2.0 ± 0.3 mU/L vs. -4.5 ± 0.5 mU/L; p = 0.01) and HOMA-IR (-0.4 ± 0.2 units vs. -1.3 ± 0.3 units; p = 0.02) were higher in T-allele carriers than in non-T-allele carriers. Conclusions: our data suggest that the genetic variant (rs2419621) of the ACSL5 gene is associated with diet response after a partial-meal replacement intervention, with greater improvements in adiposity and biochemical parameters in subjects with the T allele.

INTRODUCCIÓN: Antecedentes: se hipotetiza que el genotipo de la acil-CoA-sintetasa 5 (ACSL5) podría influir en la pérdida de peso secundaria a la restricción de energía. Objetivos: el objetivo de nuestro estudio fue analizar los efectos de la variante genética rs2419621 del gen ACSL5 sobre el cambio de peso y los parámetros metabólicos después de una dieta hipocalórica parcial de reemplazo. Métodos: estudio no aleatorizado, de centro único, con una fórmula dietética, en 44 sujetos obesos con un índice de masa corporal (IMC) superior a 35 kg/m2. Los pacientes recibieron educación nutricional y una dieta modificada con dos tomas de una fórmula hiperproteica normocalórica durante 3 meses. Los parámetros antropométricos y el perfil bioquímico se determinaron en el tiempo basal y tras 3 meses. La variante rs2419621 del gen ACSL5 se evaluó mediante reacción en cadena de la polimerasa en tiempo real. Resultados: los portadores del alelo T mostraron mejorías de peso corporal (CC vs. CT + TT; -7,4 ± 2,1 kg vs. -9,3 ± 1,8 kg; p = 0,01), índice de masa corporal (-3,1 ± 0,4 kg/m2 vs. -3,4 ± 0,5 kg/m2; p = 0,02), masa grasa (-5,2 ± 1,4 kg vs. -6,4 ± 1,2 kg; p = 0,01) y circunferencia de la cintura (-6,1 ± 1,1 cm vs. -8,6 ± 0,8 cm; p = 0,02) superiores a las de los portadores de alelos distintos de T. Solo los sujetos con alelo T mostraron una mejoría significativa en los niveles de triglicéridos (-4,6 ± 2,4 md/dL vs. -14,4 ± 2,3 mg/dL; p = 0,01). Por último, la mejoría de la insulina (-2,0 ± 0,3 mU/L vs. -4.5 ± 0.5 mU/L; p = 0,01) y HOMA-IR (-0,4 ± 0,2 unidades vs. -1,3 ± 0,3 unidades; p = 0,02) fueron mayores en los portadores de alelos T que en los portadores de alelos no T. Conclusiones: nuestros resultados sugieren que la variante genética (rs2419621) del gen ACSL5 está asociada a la respuesta a la dieta después una dieta hipocalórica parcial de reemplazo, con una mejoría superior de los parámetros relacionados con la adiposidad y los parámetros bioquímicos en los sujetos con alelo T.

LOX and ACSL5 as potential relapse markers for pancreatic cancer patients.

Pancreatic cancer is one of the most malignant diseases and has a poor prognosis. The screening and validation of biomarkers with predictive value for prognosis and treatment efficacy are important. To identify potential prognostic markers of pancreatic cancer patients, we conducted a study that included 99 pancreatic cancer patients. Three patients with PFS>18 months were enrolled in the treat group, and three patients with PFS<12 months were enrolled in the control group. Differentially expressed genes (DEGs) between these two groups were analyzed by whole-genome expression microarray. A total of 178 DEGs were identified, including 110 up-regulated and 68 down-regulated genes. Next, 24 candidate genes were selected for validation by qPCR based on fold change and previous studies. The results showed that the mRNA levels of four candidate genes, including ACSL5, SLC44A4, LOX, and TOX3, were correlated with PFS. Immunohistochemical staining was performed to validate the protein expression levels of these four markers. The results showed that patients with LOX high, ACSL5 low and TOX3 low expression had a significantly shorter PFS than those with LOX low, ACSL5 high and TOX3 high expression. Multivariable analysis revealed differentiation, tumor stage, LOX expression, and ACSL5 expression were independent prognostic factors for PFS. Then, we use the TCGA database to explore the underlying mechanism of LOX influence pancreatic cancer progression. Protein-protein interaction network of ACSL5 was established by STRING to uncover the potential regulation mechanism. Our findings reveal that LOX and ACSL5 are potential prognostic markers for the prognosis of pancreatic cancer patients.

Overexpression of Long-Chain Acyl-CoA Synthetase 5 Increases Fatty Acid Oxidation and Free Radical Formation While Attenuating Insulin Signaling in Primary Human Skeletal Myotubes.

In rodent skeletal muscle, acyl-coenzyme A (CoA) synthetase 5 (ACSL-5) is suggested to localize to the mitochondria but its precise function in human skeletal muscle is unknown. The purpose of these studies was to define the role of ACSL-5 in mitochondrial fatty acid metabolism and the potential effects on insulin action in human skeletal muscle cells (HSKMC). Primary myoblasts isolated from vastus lateralis (obese women (body mass index (BMI) = 34.7 ± 3.1 kg/m²)) were transfected with ACSL-5 plasmid DNA or green fluorescent protein (GFP) vector (control), differentiated into myotubes, and harvested (7 days). HSKMC were assayed for complete and incomplete fatty acid oxidation ([1-14C] palmitate) or permeabilized to determine mitochondrial respiratory capacity (basal (non-ADP stimulated state 4), maximal uncoupled (carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP)-linked) respiration, and free radical (superoxide) emitting potential). Protein levels of ACSL-5 were 2-fold higher in ACSL-5 overexpressed HSKMC. Both complete and incomplete fatty acid oxidation increased by 2-fold (p < 0.05). In permeabilized HSKMC, ACSL-5 overexpression significantly increased basal and maximal uncoupled respiration (p < 0.05). Unexpectedly, however, elevated ACSL-5 expression increased mitochondrial superoxide production (+30%), which was associated with a significant reduction (p < 0.05) in insulin-stimulated p-Akt and p-AS160 protein levels. We concluded that ACSL-5 in human skeletal muscle functions to increase mitochondrial fatty acid oxidation, but contrary to conventional wisdom, is associated with increased free radical production and reduced insulin signaling.

ACSL5 genotype influence on fatty acid metabolism: a cellular, tissue, and whole-body study.

BACKGROUND: Acyl-CoA Synthetase Long Chain 5 (ACSL5) gene's rs2419621 T/C polymorphism was associated with ACSL5 mRNA expression and response to lifestyle interventions. However, the mechanistic understanding of the increased response in T allele carriers is lacking. Study objectives were to investigate the effect of rs2419621 genotype and ACSL5 human protein isoforms on fatty acid oxidation and respiration. METHODS: Human ACSL5 overexpression in C2C12 mouse myoblasts was conducted to measure 14C palmitic acid oxidation and protein isoform localization in vitro. 14C palmitic acid oxidation studies and Western blot analysis of ACSL5 proteins were carried out in rectus abdominis primary myotubes from 5 rs2419621 T allele carriers and 4 non-carriers. In addition, mitochondrial high-resolution respirometry was conducted on vastus lateralis muscle biopsies from 4 rs2419621 T allele carriers and 4 non-carriers. Multiple linear regression analysis was conducted to test the association between rs2419621 genotype and respiratory quotient related pre- and post-lifestyle intervention measurements in postmenopausal women with overweight or obesity. RESULTS: In comparison to rs2419621 non-carriers, T allele carriers displayed higher levels of i) 683aa ACSL5 isoform, localized mainly in the mitochondria, playing a greater role in fatty acid oxidation in comparison to the 739aa protein isoform ii) in vitro CO2 production in rectus abdominis primary myotubes iii) in vivo fatty acid oxidation and lower carbohydrate oxidation post-intervention iv) ex vivo complex I and II tissue respiration in vastus lateralis muscle. CONCLUSIONS: These results support the conclusion that rs2419621 T allele carriers, are more responsive to lifestyle interventions partly due to an increase in the short ACSL5 protein isoform, increasing cellular, tissue and whole-body fatty acid utilization. With the increasing effort to develop personalized medicine to combat obesity, our findings provide additional insight into genotypes that can significantly affect whole body metabolism and response to lifestyle interventions.

Acyl CoA synthetase 5 (ACSL5) ablation in mice increases energy expenditure and insulin sensitivity and delays fat absorption.

OBJECTIVE: The family of acyl-CoA synthetase enzymes (ACSL) activates fatty acids within cells to generate long chain fatty acyl CoA (FACoA). The differing metabolic fates of FACoAs such as incorporation into neutral lipids, phospholipids, and oxidation pathways are differentially regulated by the ACSL isoforms. In vitro studies have suggested a role for ACSL5 in triglyceride synthesis; however, we have limited understanding of the in vivo actions of this ACSL isoform. METHODS: To elucidate the in vivo actions of ACSL5 we generated a line of mice in which ACSL5 expression was ablated in all tissues (ACSL5 (-/-) ). RESULTS: Ablation of ACSL5 reduced ACSL activity by ∼80% in jejunal mucosa, ∼50% in liver, and ∼37% in brown adipose tissue lysates. Body composition studies revealed that ACSL5 (-/-) , as compared to control ACSL5 (loxP/loxP) , mice had significantly reduced fat mass and adipose fat pad weights. Indirect calorimetry studies demonstrated that ACSL5 (-/-) had increased metabolic rates, and in the dark phase, increased respiratory quotient. In ACSL5 (-/-) mice, fasting glucose and serum triglyceride were reduced; and insulin sensitivity was improved during an insulin tolerance test. Both hepatic mRNA (∼16-fold) and serum levels of fibroblast growth factor 21 (FGF21) (∼13-fold) were increased in ACSL5 (-/-) as compared to ACSL5 (loxP/loxP) . Consistent with increased FGF21 serum levels, uncoupling protein-1 gene (Ucp1) and PPAR-gamma coactivator 1-alpha gene (Pgc1α) transcript levels were increased in gonadal adipose tissue. To further evaluate ACSL5 function in intestine, mice were gavaged with an olive oil bolus; and the rate of triglyceride appearance in serum was found to be delayed in ACSL5 (-/-) mice as compared to control mice. CONCLUSIONS: In summary, ACSL5 (-/-) mice have increased hepatic and serum FGF21 levels, reduced adiposity, improved insulin sensitivity, increased energy expenditure and delayed triglyceride absorption. These studies suggest that ACSL5 is an important regulator of whole-body energy metabolism and ablation of ACSL5 may antagonize the development of obesity and insulin resistance.

Development of fatty acid metabolism score based on gene signature for predicting prognosis and immunotherapy response in colon cancer

Purpose Metabolic reprogramming is a novel hallmark and therapeutic target of cancer. Our study aimed to establish fatty acid metabolism-associated scores based on gene signature and investigated its effects on immunotherapy in colon cancer. Methods Gene expression and clinical information were collected from Gene Expression Omnibus (GEO) database to identify a gene signature by non-negative matrix factorization (NMF) clustering and Cox regression analysis. Subsequently, we constructed the fatty acid metabolism score (FA-score) model by principal component analysis (PCA) and explored its relativity of prognosis and the response to immunotherapy in colon cancer. Finally, the Cancer Genome Atlas (TCGA) database was introduced and in vitro study was performed for verification. Results The FA-score-high group had a higher level of fatty acid metabolism and was associated with worse patient overall survival. Significantly, FA-score correlated closely with the biomarkers of immunotherapy, and the FA-score-high group had a poorer therapeutic efficacy of immune checkpoint blockade. In vitro experiments demonstrated that ACSL5 may be a critical metabolic regulatory target. Conclusions Our study provided a comprehensive analysis of the heterogeneity of fatty acid metabolism in colon cancer. We highlighted the potential clinical utility of fatty acid metabolism-related genes to be biomarkers of colon cancer prognosis and targets to improve the effect of immunotherapy (AU)