PTEN activates chaperone-mediated autophagy to regulate metabolism.

PTEN is a negative modulator of the INS-PI3K-AKT pathway and is an essential regulator of metabolism and cell growth. PTEN is one of the most commonly mutated tumor suppressors in cancer. However, PTEN overexpression extends the lifespan of both sexes of mice. We recently showed that PTEN is necessary and sufficient to activate chaperone-mediated autophagy (CMA) in the mouse liver and cultured cells. Selective protein degradation via CMA is required to suppress glycolysis and fatty acid synthesis when PTEN is overexpressed. Thus, activation of CMA downstream of PTEN might modulate health and metabolism through selective degradation of key metabolic enzymes.

Reconstruction of a fatty acid synthesis cycle from acyl carrier protein and cofactor structural snapshots.

Fatty acids (FAs) play a central metabolic role in living cells as constituents of membranes, cellular energy reserves, and second messenger precursors. A 2.6 MDa FA synthase (FAS), where the enzymatic reactions and structures are known, is responsible for FA biosynthesis in yeast. Essential in the yeast FAS catalytic cycle is the acyl carrier protein (ACP) that actively shuttles substrates, biosynthetic intermediates, and products from one active site to another. We resolve the S. cerevisiae FAS structure at 1.9 Å, elucidating cofactors and water networks involved in their recognition. Structural snapshots of ACP domains bound to various enzymatic domains allow the reconstruction of a full yeast FA biosynthesis cycle. The structural information suggests that each FAS functional unit could accommodate exogenous proteins to incorporate various enzymatic activities, and we show proof-of-concept experiments where ectopic proteins are used to modulate FAS product profiles.

Development of Schizochytrium sp. strain HS01 with high-DHA and low-saturated fatty acids production by multi-pronged adaptive evolution.

PURPOSE: Docosahexaenoic acid (DHA) is an important omega-3 unsaturated fatty acid and has been widely applied in medicine, food additives, and feed ingredients. The fermentative production of DHA using microorganisms, including Schizochytrium sp., attracted much attention due to its high production efficiency and environment friendly properties. An efficient laboratory evolution approach was used to improve the strain's performance in this study. METHODS: A multi-pronged laboratory evolution approach was applied to evolve high-yield DHA-producing Schizochytrium strain. We further employed comparative transcriptional analysis to identify transcriptional changes between the screened strain HS01 and its parent strain GS00. RESULTS: After multiple generations of ALE, a strain HS01 with higher DHA content and lower saturated fatty acids content was obtained. Low nitrogen conditions were important for enhancing DHA biosynthesis in HS01. The comparative transcriptional analysis results indicated that during the fermentation process of HS01, the expression of key enzymes in the glycolysis, the pentose phosphate pathway and the tricarboxylic acid cycle were up-regulated, while the expression of polyketide synthase genes and fatty acid synthesis genes were similar to those in GS00. CONCLUSION: The results suggest that the improved DHA production capacity of HS01 is not due to enhancement of the DHA biosynthesis pathway, but rather related to modulation of central metabolism pathways.

Recent advances in microbial production of medium chain fatty acid from renewable carbon resources: A comprehensive review.

Microbial production of medium chain length fatty acids (MCFAs) from renewable resources is becoming increasingly important in establishing a sustainable and clean chemical industry. This review comprehensively summarizes current advances in microbial MCFA production from renewable resources. Detailed information is provided on two major MCFA production pathways using various renewable resources and other auxiliary pathways supporting MCFA production to help understand the fundamentals of bio-based MCFA production. In addition, conventional and well-studied MCFA producers are classified into two categories, natural and synthetic producers, and their characteristics on MCFA production are outlined. Moreover, various engineering strategies employed to achieve the highest MCFAs production up to date are showcased together with key enzymes suggested for MCFA overproduction. Finally, future challenges and perspectives are discussed towards more efficient production of bio-based MCFA production.

Structural study of acyl carrier protein of Enterococcus faecalis and its interaction with enzymes in de novo fatty acid synthesis.

Enterococcus faecalis has recently shown signs of high antibiotic resistance. These bacteria can endure extremes of temperature and this may be due to the high thermostability of its proteins. E. faecalis has two acyl carrier proteins (ACPs), AcpA (EfAcpA), which is essential for de novo fatty acid synthesis (FAS), and EfAcpB, which plays an auxiliary role in the incorporation of exogenous fatty acids. Structural studies on EfAcpA and its interaction with FAS enzymes have not yet been reported. Here, we investigated the structures of EfAcpA using NMR spectroscopy, showing that EfAcpA consists of three α-helices with a long α2α3 loop, while the other ACPs have four α-helices. CD experiments showed that the melting temperature of EfAcpA is 76.3 °C and the Ala mutation for Ile10 reduced it dramatically by 29.5 °C. Highly conserved Ile10 of EfAcpA mediates compact intramolecular packing and promotes high thermostability. A docking simulation of EfAcpA and ß-ketoacyl-ACP synthase III (EfKAS III) showed that the α2α3 loop of EfAcpA contributes to specific protein-protein interactions (PPI) with EfKAS III. Unconserved charged residues, Lys52 and Glu54, in the α2α3 loop of EfAcpA formed specific electrostatic interactions with Asp 226 and Arg217 of EfKAS III, respectively. Binding interactions between EfAcpA and EfKASIII may provide insights for designing PPI inhibitors targeting FAS in E. faecalis to overcome its antibacterial resistance.

The MAP-Kinase HOG1 Controls Cold Adaptation in Rhodosporidium kratochvilovae by Promoting Biosynthesis of Polyunsaturated Fatty Acids and Glycerol.

The aim of this study was to investigate the role of RKHog1 in the cold adaptation of Rhodosporidium kratochvilovae strain YM25235 and elucidate the correlation of biosynthesis of polyunsaturated fatty acids (PUFAs) and glycerol with its cold adaptation. The YM25235 strain was subjected to salt, osmotic, and cold stress tolerance analyses. mRNA levels of RKhog1, Δ12/15-fatty acid desaturase gene (RKD12), RKMsn4, HisK2301, and RKGPD1 in YM25235 were detected by reverse transcription quantitative real-time PCR. The contents of PUFAs, such as linoleic acid (LA) and linolenic acid (ALA) was measured using a gas chromatography-mass spectrometer, followed by determination of the growth rate of YM25235 and its glycerol content at low temperature. The RKHog1 overexpression, knockout, and remediation strains were constructed. Stress resistance analysis showed that overexpression of RKHog1 gene increased the biosynthesis of glycerol and enhanced the tolerance of YM25235 to cold, salt, and osmotic stresses, respectively. Inversely, the knockout of RKHog1 gene decreased the biosynthesis of glycerol and inhibited the tolerance of YM25235 to different stresses. Fatty acid analysis showed that the overexpression of RKHog1 gene in YM25235 significantly increased the content of LA and ALA, but RKHog1 gene knockout YM25235 strain had decreased content of LA and ALA. In addition, the mRNA expression level of RKD12, RKMsn4, RKHisK2301, and RKGPD1 showed an increase at 15 °C after RKHog1 gene overexpression but were unchanged at 30 °C. RKHog1 could regulate the growth adaptability and PUFA content of YM25235 at low temperature and this could be helpful for the cold adaptation of YM25235.

ATGL is a biosynthetic enzyme for fatty acid esters of hydroxy fatty acids.

Branched fatty acid (FA) esters of hydroxy FAs (HFAs; FAHFAs) are recently discovered lipids that are conserved from yeast to mammals1,2. A subfamily, palmitic acid esters of hydroxy stearic acids (PAHSAs), are anti-inflammatory and anti-diabetic1,3. Humans and mice with insulin resistance have lower PAHSA levels in subcutaneous adipose tissue and serum1. PAHSA administration improves glucose tolerance and insulin sensitivity and reduces inflammation in obesity, diabetes and immune-mediated diseases1,4-7. The enzyme(s) responsible for FAHFA biosynthesis in vivo remains unknown. Here we identified adipose triglyceride lipase (ATGL, also known as patatin-like phospholipase domain containing 2 (PNPLA2)) as a candidate biosynthetic enzyme for FAHFAs using chemical biology and proteomics. We discovered that recombinant ATGL uses a transacylation reaction that esterifies an HFA with a FA from triglyceride (TG) or diglyceride to produce FAHFAs. Overexpression of wild-type, but not catalytically dead, ATGL increases FAHFA biosynthesis. Chemical inhibition of ATGL or genetic deletion of Atgl inhibits FAHFA biosynthesis and reduces the levels of FAHFA and FAHFA-TG. Levels of endogenous and nascent FAHFAs and FAHFA-TGs are 80-90 per cent lower in adipose tissue of mice in which Atgl is knocked out specifically in the adipose tissue. Increasing TG levels by upregulating diacylglycerol acyltransferase (DGAT) activity promotes FAHFA biosynthesis, and decreasing DGAT activity inhibits it, reinforcing TGs as FAHFA precursors. ATGL biosynthetic transacylase activity is present in human adipose tissue underscoring its potential clinical relevance. In summary, we discovered the first, to our knowledge, biosynthetic enzyme that catalyses the formation of the FAHFA ester bond in mammals. Whereas ATGL lipase activity is well known, our data establish a paradigm shift demonstrating that ATGL transacylase activity is biologically important.

FabT, a Bacterial Transcriptional Repressor That Limits Futile Fatty Acid Biosynthesis.

Phospholipids are vital membrane constituents that determine cell functions and interactions with the environment. For bacterial pathogens, rapid adjustment of phospholipid composition to changing conditions during infection can be crucial for growth and survival. Fatty acid synthesis (FASII) regulators are central to this process. This review puts the spotlight on FabT, a MarR-family regulator of FASII characterized in streptococci, enterococci, and lactococci. Roles of FabT in virulence, as reported in mouse and nonhuman primate infection models, will be discussed. We present FabT structure, the FabT regulon, and changes in FabT regulation according to growth conditions. A unique feature of FabT concerns its modulation by an unconventional corepressor, acyl-acyl-carrier protein (ACP). Some bacteria express two ACP proteins, which are distinguished by their interactions with endogenous or exogenous fatty acid sources, one of which causes strong FabT repression. This system seems to allow preferred use of environmental fatty acids, thereby saving energy by limiting futile FASII activity. Control of fabT expression and FabT activity link various metabolic pathways to FASII. The various physiological consequences of FabT loss summarized here suggest that FabT has potential as a narrow range therapeutic target.

Control of Unsaturation in De Novo Fatty Acid Biosynthesis by FabA.

Carrier protein-dependent biosynthesis provides a thiotemplated format for the production of natural products. Within these pathways, many reactions display exquisite substrate selectivity, a regulatory framework proposed to be controlled by protein-protein interactions (PPIs). In Escherichia coli, unsaturated fatty acids are generated within the de novo fatty acid synthase by a chain length-specific interaction between the acyl carrier protein AcpP and the isomerizing dehydratase FabA. To evaluate PPI-based control of reactivity, interactions of FabA with AcpP bearing multiple sequestered substrates were analyzed through NMR titration and guided high-resolution docking. Through a combination of quantitative binding constants, residue-specific perturbation analysis, and high-resolution docking, a model for substrate control via PPIs has been developed. The in silico results illuminate the mechanism of FabA substrate selectivity and provide a structural rationale with atomic detail. Helix III positioning in AcpP communicates sequestered chain length identity recognized by FabA, demonstrating a powerful strategy to regulate activity by allosteric control. These studies broadly illuminate carrier protein-dependent pathways and offer an important consideration for future inhibitor design and pathway engineering.

Mucor circinelloides: a model organism for oleaginous fungi and its potential applications in bioactive lipid production.

Microbial oils have gained massive attention because of their significant role in industrial applications. Currently plants and animals are the chief sources of medically and nutritionally important fatty acids. However, the ever-increasing global demand for polyunsaturated fatty acids (PUFAs) cannot be met by the existing sources. Therefore microbes, especially fungi, represent an important alternative source of microbial oils being investigated. Mucor circinelloides-an oleaginous filamentous fungus, came to the forefront because of its high efficiency in synthesizing and accumulating lipids, like γ-linolenic acid (GLA) in high quantity. Recently, mycelium of M. circinelloides has acquired substantial attraction towards it as it has been suggested as a convenient raw material source for the generation of biodiesel via lipid transformation. Although M. circinelloides accumulates lipids naturally, metabolic engineering is found to be important for substantial increase in their yields. Both modifications of existing pathways and re-formation of biosynthetic pathways in M. circinelloides have shown the potential to improve lipid levels. In this review, recent advances in various important metabolic aspects of M. circinelloides have been discussed. Furthermore, the potential applications of M. circinelloides in the fields of antioxidants, nutraceuticals, bioremediation, ethanol production, and carotenoids like beta carotene and astaxanthin having significant nutritional value are also deliberated.

Protection of Quiescence and Longevity of IgG Memory B Cells by Mitochondrial Autophagy.

The development of long-lived immune memory cells against pathogens is critical for the success of vaccines to establish protection against future infections. However, the mechanisms governing the long-term survival of immune memory cells remain to be elucidated. In this article, we show that the maintenance mitochondrial homeostasis by autophagy is critical for restricting metabolic functions to protect IgG memory B cell survival. Knockout of mitochondrial autophagy genes, Nix and Bnip3, leads to mitochondrial accumulation and increases in oxidative phosphorylation and fatty acid synthesis, resulting in the loss of IgG+ memory B cells in mice. Inhibiting fatty acid synthesis or silencing necroptosis gene Ripk3 rescued Nix-/-Bnip3-/- IgG memory B cells, indicating that mitochondrial autophagy is important for limiting metabolic functions to prevent cell death. Our results suggest a critical role for mitochondrial autophagy in the maintenance of immunological memory by protecting the metabolic quiescence and longevity of memory B cells.

MS4A15 acts as an oncogene in ovarian cancer through reprogramming energy metabolism.

Membrane-spanning 4-domains subfamily A 15 (MS4A15) belongs to transmembrane proteins and has been recognized as a regulator of various biological events including cell metabolism. Dysregulation of cell metabolism is a component of malignant transformation in numerous types of tumors, including ovarian cancer (OC). Nevertheless, whether MS4A15 is involved in OC progression remains obscure, as well as the underlying mechanisms. In the present study, we found that MS4A15 expression was significantly up-regulated in tumor tissues from OC patients compared with the matched normal adjacent samples. Higher MS4A15 expression predicted poorer overall survival rate in patients with OC. Our in vitro studies subsequently showed that MS4A15 knockdown markedly reduced the proliferation of OC cells, while its over-expression accelerated the proliferative capacity of OC cells through mediating the progression of G0/G1 cell cycle. Consistently, stable MS4A15 knockdown strongly inhibited the tumor growth in the established xenograft mouse models, along with evidently decreased expression of KI-67 positive staining. However, xenograft mouse models with MS4A15 over-expression exerted significantly accelerated tumor growth rates. We then found that MS4A15 reprogrammed energy metabolism to enhance OC progression. Under normal status, MS4A15 enhanced de novo lipid synthesis in OC cells. Upon glucose starvation, MS4A15 elevated oxidative phosphorylation (OXPHOS) to protect OC cells from starvation-induced cell death. Taken together, our findings demonstrated that MS4A15 may play an essential role in promoting OC growth mainly via reprogramming energy metabolism, and thus could be considered as a novel therapeutic target for OC treatment.

Signatures of selection in recently domesticated macadamia.

Macadamia is a high value nut crop that is recently domesticated, ideal for testing the effect of artificial selection. Here, we sequence the genome of Hawaiian cultivar 'Kau' and assemble into 794 Mb in 14 pseudo-chromosomes with 37,728 genes. Genome analysis reveals a whole-genome duplication event, occurred 46.8 million years ago. Gene expansions occurred in gene families involves in fatty acid biosynthesis. Gene duplication of MADS-Box transcription factors in proanthocyanidin biosynthesis are relevant for seed coat development. Genome re-sequencing of 112 accessions reveals the origin of Hawaiian cultivars from Mount Bauple in southeast Queensland in Australia. Selective sweeps are detected in macadamia cultivars, including genes involved in fatty acid biosynthesis, seed coat development, and heat stress response. Such strong effects of artificial selection in few generations reveals the genomic basis for 'one-step operation' for clonal crop domestication. The knowledge gained could accelerate domestication of new crops from wild species.

Plasma metabolomics study reveals the critical metabolic signatures for benzene-induced hematotoxicity.

Metabolomics has been used to explore the molecular mechanism and screen biomarkers. However, the critical metabolic signatures associated with benzene-induced hematotoxicity remain elusive. Here, we performed a plasma metabolomics study in 86 benzene-exposed workers and 76 healthy controls, followed by a validation analysis in mice, to investigate the dynamical change of the metabolic profile. We found that 8 fatty acids were significantly altered in both benzene-exposed worker and benzene-exposed animal models. These metabolites were significantly associated with S-phenylmercapturic acid and WBC, and they mediated the benzene-induced WBC decline. Furthermore, in vivo results confirm that fatty acid levels were dynamically altered, characterized by a decrease at 15 days and then sharp increases at 30 and 45 days. Following these identified fatty acids, the potential metabolic pathways were investigated. Fatty acids, as precursors for fatty acid oxidation, may disturb the balance of fatty acid biosynthesis and degradation. Our results reveal that fatty acid metabolism was strongly reprogrammed after benzene exposure. This abnormal change of fatty acids might be the key metabolic signature associated with benzene-induced hematotoxicity.

Classical prescription Dachuanxiong Formula delays nitroglycerin-induced pain response in migraine mice through reducing endothelin-1 level and regulating fatty acid biosynthesis.

ETHNOPHARMACOLOGICAL RELEVANCE: Dachuanxiong Formula (DCXF) is a classical Chinese medicine prescription and is composed of dried rhizomes from Ligusticum striatum DC. (Chuanxiong Rhizoma) and Gastrodia elata Bl. (Gastrodiae Rhizoma) at the ratio of 4:1 (w/w). It has been used as Chinese medicine prescription for thousands of years. DCXF is used traditionally to treat many diseases, including migraine, atherosclerosis and ischemic stroke. AIM OF THE STUDY: This study aimed to investigate the effects of DCXF on pain response in migraine mice, and the underlying mechanisms using proteomics and bioinformatics analyses. MATERIALS AND METHODS: DCXF extract was prepared by mixing Chuanxiong Rhizoma and Gastrodiae Rhizoma at a mass ratio of 4:1 (w/w). After extraction, the extract was filtered prior to high performance liquid chromatography (HPLC) analysis. Nitroglycerin (NTG) was used to establish a mouse migraine model, and a behaviour study was conducted by hot plate test. In addition, proteomics and bioinformatics studies were conducted to investigate the mechanisms of DCXF-mediating anti-migraine treatment. RESULTS: Our results showed that there were significant differences in the latencies between NTG-treated and DCXF low dose- and high doses-treated groups at 30 min after NTG injection, this suggested that DCXF could ameliorate pain response in migraine mice. Besides, the plasma levels of endothelin-1 were also measured. NTG group significantly enhanced the endothelin-1 level compared to the control group. In contrast, DCXF low dose and high dose groups significantly reduced this level compared to NTG group. In addition, the underlying mechanisms were also investigated. Our results demonstrated that the anti-migraine treatment of DCXF was highly associated with fatty acid synthesis, suggesting that DCXF ameliorated pain response through reducing endothelin-1 level and regulating fatty acid synthesis. CONCLUSIONS: The present study revealed the anti-migraine effect of DCXF in migraine mice and provided insights into the mechanisms of DCXF-mediating anti-migraine treatment.

Semi-rational Engineering of a Promiscuous Fatty Acid Hydratase for Alteration of Regioselectivity.

Fatty acid hydratases (FAHs) catalyze regio- and stereo-selective hydration of unsaturated fatty acids to produce hydroxy fatty acids. Fatty acid hydratase-1 (FA-HY1) from Lactobacillus Acidophilus is the most promiscuous and regiodiverse FAH identified so far. Here, we engineered binding site residues of FA-HY1 (S393, S395, S218 and P380) by semi-rational protein engineering to alter regioselectivity. Although it was not possible to obtain a completely new type of regioselectivity with our mutant libraries, a significant shift of regioselectivity was observed towards cis-5, cis-8, cis-11, cis-14, cis-17-eicosapentaenoic acid (EPA). We identified mutants (S393/S395 mutants) with excellent regioselectivity, generating a single hydroxy fatty acid product from EPA (15-OH product), which is advantageous from application perspective. This result is impressive given that wild-type FA-HY1 produces a mixture of 12-OH and 15-OH products at 63 : 37 ratio (12-OH : 15-OH). Moreover, our results indicate that native FA-HY1 is at its limit in terms of promiscuity and regiospecificity, thus it may not be possible to diversify its product portfolio with active site engineering. This behavior of FA-HY1 is unlike its orthologue, fatty acid hydratase-2 (FA-HY2; 58 % sequence identity to FA-HY1), which has been shown earlier to exhibit significant promiscuity and regioselectivity changes by a few active site mutations. Our reverse engineering from FA-HY1 to FA-HY2 further demonstrates this conclusion.

Highland barley Monascus purpureus Went extract ameliorates high-fat, high-fructose, high-cholesterol diet induced nonalcoholic fatty liver disease by regulating lipid metabolism in golden hamsters.

ETHNOPHARMACOLOGICAL RELEVANCE: Hepatocyte lipid accumulation is the main feature in the early stage of nonalcoholic fatty liver disease (NAFLD). Highland barley Monascus purpureus Went (HBMPW), a fermentation product of Hordeum vulgare Linn. var. nudum Hook. f. has traditionally been used as fermented foods in Tibet with the effect of reducing blood lipid in folk medicine. AIM OF THE STUDY: This study investigated the protective effects and molecular mechanism of highland barley Monascus purpureus Went extract (HBMPWE) on NAFLD in syrian golden hamster fed with high-fat, high-fructose, high-cholesterol diet (HFFCD). MATERIALS AND METHODS: HFFCD-induced NAFLD golden hamster model was established and treated with HBMPWE. Liver index, biochemical index, and hematoxylin and eosin (HE) staining were observed. Liver metabolomics and western blot analysis were employed. RESULTS: Our study found that HBMPWE ameliorated HFFCD induced dyslipidemia, weight gain and elevated the liver index. In addition, HBMPWE treatment significantly attenuated lipid accumulation in the liver and modulated lipid metabolism (sphingolipid, glycerophospholipid). Our data demonstrated that HBMPWE not only regulated the expression of proteins related to fatty acid synthesis and decomposition (SREBP-1/ACC/FAS/AceS1, PPARα/ACSL/CPT1/ACOX1), but also regulated the expression of proteins related to cholesterol synthesis and clearance (HMGCR, LDLR, CYP7A1). CONCLUSIONS: HBMPWE improved NAFLD through multiple pathways and multiple targets in body metabolism and could be used as a functional food to treat NAFLD and other lipid metabolic disorders.

Effect of Vancomycin on Cellular Fatty Acid Profiles of Vancomycin-Susceptible and Nonsusceptible Staphylococcus aureus.

Vancomycin is widely used for treatment of infection caused by methicillin-resistant Staphylococcus aureus (MRSA) leading to an increasing appearance of low-level vancomycin-resistant isolates called heterogeneous vancomycin-intermediate S. aureus (hVISA). The mechanism of vancomycin tolerance in hVISA is still unclear. This study aimed to investigate the fatty acid compositions of S. aureus isolates under the stress environment with vancomycin. The different responses of hVISA and vancomycin-susceptible S. aureus (VSSA) may lead to more understanding the mechanism. The bacterial lipid profiles were tested three times from three extractions of each isolate cultured on tryptic soy agar (TSA) and TSA with vancomycin. Of the 30 MRSA isolates studied, 13, 12, and 5 isolates were VSSA, hVISA, and VISA, respectively. The analysis of bacterial lipid profiles showed that under vancomycin stress, there was a reduction of straight chain fatty acids (SCFAs) in VSSA isolates but an increase in branched chain fatty acids (BCFAs). In contrast, the hVISA group exhibited an increase only in the BCFAs but not in SCFAs. Of interest, vancomycin had no effect on either BCFAs or SCFAs of the VISA cells. This study provided information of bacterial adaptation during stress with vancomycin that may be helpful to overcome the resistant bacteria.

Increased serum cholesterol and long-chain fatty acid levels are associated with the efficacy of nivolumab in patients with non-small cell lung cancer.

BACKGROUND: Lipids have immunomodulatory functions and the potential to affect cancer immunity. METHODS: The associations of pretreatment serum cholesterol and long-chain fatty acids with the objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were evaluated in 148 patients with non-small cell lung cancer who received nivolumab. RESULTS: When each lipid was separately evaluated, increased low-density lipoprotein (LDL)-cholesterol (P < 0.001), high-density lipoprotein (HDL)-cholesterol (P = 0.014), total cholesterol (P = 0.007), lauric acid (P = 0.015), myristic acid (P = 0.022), myristoleic acid (P = 0.035), stearic acid (P = 0.028), linoleic acid (P = 0.005), arachidic acid (P = 0.027), eicosadienoic acid (P = 0.017), dihomo-γ-linolenic acid (P = 0.036), and behenic acid levels (P = 0.032) were associated with longer PFS independent of programmed death ligand 1 (PD-L1) expression. Meanwhile, increased LDL-cholesterol (P < 0.001), HDL-cholesterol (P = 0.009), total cholesterol (P = 0.036), linoleic acid (P = 0.014), and lignoceric acid levels (P = 0.028) were associated with longer OS independent of PD-L1 expression. When multiple lipids were evaluated simultaneously, LDL-cholesterol (P = 0.003), HDL-cholesterol (P = 0.036), and lauric acid (P = 0.036) were independently predictive of PFS, and LDL-cholesterol (P = 0.008) and HDL-cholesterol (P = 0.031) were predictive of OS. ORR was not associated with any serum lipid. CONCLUSIONS: Based on the association of prolonged survival in patients with increased serum cholesterol and long-chain fatty acid levels, serum lipid levels may be useful for predicting the efficacy of immune checkpoint inhibitor therapy.

Elongase of very long chain fatty acids 6 (ELOVL6) promotes lipid synthesis in buffalo mammary epithelial cells.

Recent studies have shown elongase of very-long-chain fatty acids 6 (ELOVL6) is a vital protein for endogenous synthesis of saturated and monounsaturated long-chain fatty acids in some mammals. Nevertheless, its role in lipid synthesis in buffalo mammary gland is still unclear. In this work, the full-length coding sequence (CDS) of ELOVL6 was cloned and identified from buffalo mammary gland. As a result, the CDS of this gene is 795 bp, which encodes a polypeptide of 264 amino acid residues. The buffalo ELOVL6 contains an ELO domain which belongs to the ELO superfamily. Among the 10 tissues of buffalo in peak lactation detected by RT-qPCR, the expression level of ELOVL6 was the highest in the brain, followed by the spleen, and then decreased in the mammary gland, muscle, kidney, heart, liver, rumen, intestine and lung. However, only the expression in the brain and spleen was statistically different from that in other tissues (p < 0.05). Compared with that of the dry-off period, the mRNA abundance of ELOVL6 in the mammary gland was significantly increased in peak lactation. The experiments based on lentivirus transfection in buffalo mammary epithelial cells (BuMECs) displayed that the overexpression of ELOVL6 markedly promoted the expression of INSIG1, INSIG2, SREBP, PPARG, FASN, GPAM, DGAT2 and APGAT6 genes, and the knockdown of ELOVL6 significantly decreased the mRNA abundance of INSIG2, SREBP, FASN, SCD, GPAM, APGAT6 and TIP47 genes. In addition, the increase or decrease of ELOVL6 expression level also caused the corresponding change of total triglyceride content in the BuMECs. The results here suggest that the ELOVL6 can catalyse the synthesis of long-chain fatty acids in the BuMECs, and it can indirectly affect the expression of genes related to milk fat synthesis through its catalytic products to promote the lipid biosynthesis of BuMECs.