Exogenous Fatty Acids Research Articles

Abstract A073: Metabolism of saturated fatty acids accelerates Src-mediated prostate tumor progression

Abstract The association of dietary fatty acids (FAs) with the risk of aggressive prostate cancer is controversial. The mechanisms of supporting how dietary FAs promote cancer progression are largely unknown. The expression and/or activity of Src family kinases are frequently elevated in several cancers, including advanced prostate cancer. This study demonstrates that dietary FAs accelerated Src-mediated prostate tumorigenesis and prostate cancer cell growth in vivo. Additionally, high dietary fat compromised the ability of dasatinib to block the oncogenic signaling of Src kinase. Metabolism of exogenous FAs, in particular palmitic and myristic acids, increased biosynthesis of acyl-CoAs and altered ceramide levels, in particular C16:0 ceramide. The combination of these effects elevated levels of myristoylated Src, increased the amount of Src in detergent resistant membranes, and enhanced Src kinase mediated oncogenic signaling. Targeting myristoylation of Src kinase, which is required for its association at the cellular membrane, blocked high fat diet-accelerated tumorigenesis in vivo. These findings illustrate how the metabolism of saturated FAs can accelerate Src-driven prostate tumor progression and suggest that prostate cancer survivors may benefit from a diet low in saturated fat. Citation Format: SUNGJIN KIM, Xiangkun Yang, Qianjin Li, Meng Wu, Zanna Beharry, Michael Bartlett, Alicja Bielawska, Houjian Cai. Metabolism of saturated fatty acids accelerates Src-mediated prostate tumor progression [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A073.

Abstract 372: Obesity matters: Prostate cancers that overexpress fatty acid binding protein 5 are more common in men who are overweight or obese

Abstract BACKGROUND: One of the hallmarks of the malignant phenotype is an increase in the cell's demand for fatty acids (FA). Many cancers, including prostate cancer, show increased expression of fatty acid synthase (FASN), a multi-component enzyme that catalyzes the de novo synthesis of the fatty acid palmitate. However recent observations suggest that alternate mechanisms for FA acquisition are also important, including the utilization of exogenous palmitate when it's available. Recently, through a biopsy-based molecular analysis of high risk prostate cancer, we identified a tumor subtype with very high (>10 fold) "outlier" overexpression of fatty acid binding protein 5 (FABP5). FABP5 is involved in lipid transport and signaling, and it facilitates the utilization of palmitate and other FAs from outside of the cell. De novo palmitate synthesis by the FASN pathway is energetically expensive compared to utilization of exogenous fatty acids. STUDY DESIGN: We proposed that prostate cancers that can efficiently utilize exogenous palmitate are at a selective advantage when dietary FAs are abundant. In this study, to test that hypothesis, we compared FABP5 and FASN expression levels in prostate cancers obtained from diagnostic biopsies from normal weight, overweight and obese study subjects. A total of 201 consecutive eligible prostate biopsy patients were prospectively enrolled; 151 (75%) of these patients were cancer positive. Prostate cancer FABP5 and FASN mRNA expression were measured by qrtPCR and FABP5/FASN and FASN/FABP5 expression ratios were determined for each cancer positive core. BMI and self-identified race were obtained from hospital records. RESULTS: The expression of FABP5 and the FABP5/FASN expression ratio were significantly higher in overweight and obese individuals compared to normal weight individuals (mean FABP5/FASN overexpression ratio of 20.2 in overweight/obese subjects vs 4.0 in normal weight subjects; p < 0.05). The highest levels of prostate cancer FABP5 outlier overexpression (FABP5/FASN > 100) were observed in African American subjects with BMI > 30, and high levels of FABP5 outlier overexpression were more strongly associated with overall Gleason sum in African American than in European American subjects. CONCLUSIONS: In our study population, prostate cancer subtypes with high levels of FABP5 overexpression were more common in biopsy patients who were overweight or obese compared to normal weight patients. The highest levels of FABP5 overexpression in were observed in prostate cancers from obese African American subjects. Such FABP5 dominant prostate cancers may utilize exogenous fatty acids more efficiently and be more sensitive to dietary interventions than the more widely studied FASN dominant prostate cancers. Funding: DOD Prostate Cancer Research Program Awards W8XWH-10-1-0543 (Grizzle, PI) and W81XWH-10-1-0544 (Gaston, PI) Citation Format: Sandra M. Gaston, Soroush Rais-Bahrami, James Kearns, Dennis Otali, Denise Oelschlager, Mark S. DeGuenther, Jeffrey W. Nix, Peter N. Kolettis, James E. Bryant, Robert A. Oster, William E. Grizzle. Obesity matters: Prostate cancers that overexpress fatty acid binding protein 5 are more common in men who are overweight or obese [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 372.

Acute Resistance Exercise Improves Postprandial Lipid Metabolism in Men with Obesity and Prediabetes

Purpose: The purpose of this study was to characterize the effect of acute resistance exercise on post-prandial lipid metabolism in obese men with prediabetes using a novel dual-tracer approach. Participants: Ten men with obesity (age 47 ± 10, BMI 33 ± 2) and prediabetes (fasting glucose 110 ± 4 mg/dL, HbA1c 5.6% ± .2%, 2-hour OGTT glucose 162 ± 14 mg/dL). Methods: Randomized cross-over design. Participants completed a 1-hour bout of whole-body resistance exercise (RE: 8 exercises, 3 sets, 12 reps, 80% 1RM), or 1-hour of rest on separate visits. Participants received a constant infusion of [U-13C16] palmitate and consumed a mixed meal containing 10 mg/kg body weight of [(13C4-palmitate)3] tripalmitin to assess incorporation of endogenous and exogenous fatty acids into postprandial lipids, respectively. Plasma samples were analyzed for total triglyceride (TG), chylomicron, triglyceride rich lipoprotein (TRL), and fatty acid concentrations and isotopic enrichment of tracers. Indirect calorimtery was used to measure whole-body lipid oxidation. Skeletal muscle biopsies were used to measure muscle mitochondrial fatty acid oxidation capacity using high-resolution respirometry. Results: Compared to rest, a single bout of RE reduced post-prandial total TG, chylomicron-TG, VLDL-TG, and TRL-TG concentration area under the curve (all p<0.05). Enrichment analyses revealed the contribution of meal-derived TG to circulating chylomicrons and TRL was significantly reduced after RE, as was the contribution of TG in chylomicrons that came from the meal (all p<0.05). RE increased whole-body lipid oxidation for up to three hours after the exercise session, and significantly improved skeletal muscle oxidative capacity (p=.031). Conclusions: Resistance exercise improves post-prandial lipid clearance and oxidation, thereby reducing post-prandial triglyceride excursions in men with obesity and prediabetes. These improvements could lower the risk of CVD and progression to T2DM. Disclosure A. Bittel: None. D. Bittel: None. B.W. Patterson: None. B. Mittendorfer: None. W.T. Cade: None.

Cloning and functional characterization of long-chain acyl-CoA synthetase 1 from the mesocarp of African oil palm (Elaeis guineensis Jacq.)

African oil palm (Elaeis guineensis Jacq.) is the highest-yielding oil crop in the world. Recent studies have shown the importance of long-chain acyl-CoA synthetases (LACSs) in lipid biosynthesis and degradation, but few studies have focused on oil palm. In this work, we found that transcription of EgLACS1was positively correlated with lipid accumulation in the oil palm mesocarp. In order to clarify the role of EgLACS1 on lipid metabolism, three variants of the EgLACS1 gene were cloned from oil palm and designated EgLACS1-V1, EgLACS1-V2, and EgLACS1-V3. Sequence analysis revealed that the three variant proteins contained several highly conserved motifs, shared important sequence similarities with other known LACS1s, and demonstrated that EgLACS1-V1, EgLACS1-V2 and EgLACS1-V3 were 666-, 664- and 601-aminoacid proteins, respectively. All of the three variant genes encodingEgLACS1 were expressed and tested for their functionality in an acyl-coenzyme-A synthetase- (ACS-) deficient mutant yeast strain YB525. Only EgLACS1-V1 and EgLACS1-V2 could rescue the growth deficiency (an inability to grow on a fatty acid auxotrophic medium) of YB525 in complementation tests. Using a fluorescent fatty acid analogue confirmed that EgLACS1-V1 and EgLACS1-V2 facilitated exogenous fatty acid uptake. EgLACS1 overexpression in yeast reduced fatty acid content. All these results suggested that not only did both the EgLACS1-V1 and EgLACS1-V2 enzymes exhibit acyl-coenzyme-A activities, but that they were also involved in the transfer of fatty acid-coenzyme A. They may also take part in the storage of lipid during fruit development in oil palm. The characterization of EgLACS1 will provide a molecular basis for the study of acyl-coenzyme A synthetase-mediated lipid synthesis and degradation in oil palm.

Evaluation of transcription profile of acetyl-CoA carboxylase (ACCase) and acyl-ACP synthetase (AAS) to reveal their roles in induced lipid accumulation of Synechococcus sp. HS01

Abstract It was earlier shown that the mixotrophic cultivation of Synechococcus sp. HS01 in ostrich oil-containing BG11 medium leads to an up to 2.82- fold increase in lipid productivity compared with autotrophic condition. A follow-up investigation was carried out to divulge whether conditions that would increase the lipid content in Synechococcus sp. HS01, bringing about constantly more pool towards the main route for fatty acids synthesis. To this end, the expression patterns of two genes including acc as the main enzyme involved in fatty acid synthesis pathway, converting Acetyl-CoA to Malonyl-CoA and aas gene which convert free fatty acids to active Acyl carrier protein (ACP) (through esterification) were carefully analyzed under different culture conditions. While there is a direct association between the expression of acc gene and changes in lipid content of glucose and acetate-grown cultures, no direct relationship exists between the expression of this gene in ostrich oil-grown culture and nitrogen-deficient conditions. Reduced acc gene expression and increased expression of aas gene in conjunction with increased lipid contents in ostrich oil-grown cultures indicated that exogenous fatty acids can be applied directly to the intracellular lipid synthesis and a possible strategy for achieving greater amount of lipids produced by cyanobacteria.

Substantial Metabolic Activity of Human Brown Adipose Tissue during Warm Conditions and Cold-Induced Lipolysis of Local Triglycerides

SummaryCurrent understanding of in vivo human brown adipose tissue (BAT) physiology is limited by a reliance on positron emission tomography (PET)/computed tomography (CT) scanning, which has measured exogenous glucose and fatty acid uptake but not quantified endogenous substrate utilization by BAT. Six lean, healthy men underwent 18fluorodeoxyglucose-PET/CT scanning to localize BAT so microdialysis catheters could be inserted in supraclavicular BAT under CT guidance and in abdominal subcutaneous white adipose tissue (WAT). Arterial and dialysate samples were collected during warm (∼25°C) and cold exposure (∼17°C), and blood flow was measured by 133xenon washout. During warm conditions, there was increased glucose uptake and lactate release and decreased glycerol release by BAT compared with WAT. Cold exposure increased blood flow, glycerol release, and glucose and glutamate uptake only by BAT. This novel use of microdialysis reveals that human BAT is metabolically active during warm conditions. BAT activation substantially increases local lipolysis but also utilization of other substrates such as glutamate.

Staphylococcus aureus Utilizes Host-Derived Lipoprotein Particles as Sources of Fatty Acids.

Methicillin-resistant Staphylococcus aureus (MRSA) is a threat to global health. Consequently, much effort has focused on the development of new antimicrobials that target novel aspects of S. aureus physiology. Fatty acids are required to maintain cell viability, and bacteria synthesize fatty acids using the type II fatty acid synthesis (FASII) pathway. FASII is significantly different from human fatty acid synthesis, underscoring the therapeutic potential of inhibiting this pathway. However, many Gram-positive pathogens incorporate exogenous fatty acids, bypassing FASII inhibition and leaving the clinical potential of FASII inhibitors uncertain. Importantly, the source(s) of fatty acids available to pathogens within the host environment remains unclear. Fatty acids are transported throughout the body by lipoprotein particles in the form of triglycerides and esterified cholesterol. Thus, lipoproteins, such as low-density lipoprotein (LDL), represent a potentially rich source of exogenous fatty acids for S. aureus during infection. We sought to test the ability of LDLs to serve as a fatty acid source for S. aureus and show that cells cultured in the presence of human LDLs demonstrate increased tolerance to the FASII inhibitor triclosan. Using mass spectrometry, we observed that host-derived fatty acids present in the LDLs are incorporated into the staphylococcal membrane and that tolerance to triclosan is facilitated by the fatty acid kinase A, FakA, and Geh, a triacylglycerol lipase. Finally, we demonstrate that human LDLs support the growth of S. aureus fatty acid auxotrophs. Together, these results suggest that human lipoprotein particles are a viable source of exogenous fatty acids for S. aureus during infection.IMPORTANCE Inhibition of bacterial fatty acid synthesis is a promising approach to combating infections caused by S. aureus and other human pathogens. However, S. aureus incorporates exogenous fatty acids into its phospholipid bilayer. Therefore, the clinical utility of targeting bacterial fatty acid synthesis is debated. Moreover, the fatty acid reservoir(s) exploited by S. aureus is not well understood. Human low-density lipoprotein particles represent a particularly abundant in vivo source of fatty acids and are present in tissues that S. aureus colonizes. Herein, we establish that S. aureus is capable of utilizing the fatty acids present in low-density lipoproteins to bypass both chemical and genetic inhibition of fatty acid synthesis. These findings imply that S. aureus targets LDLs as a source of fatty acids during pathogenesis.

Modulation of Haemophilus influenzae interaction with hydrophobic molecules by the VacJ/MlaA lipoprotein impacts strongly on its interplay with the airways

Airway infection by nontypeable Haemophilus influenzae (NTHi) associates to chronic obstructive pulmonary disease (COPD) exacerbation and asthma neutrophilic airway inflammation. Lipids are key inflammatory mediators in these disease conditions and consequently, NTHi may encounter free fatty acids during airway persistence. However, molecular information on the interplay NTHi-free fatty acids is limited, and we lack evidence on the importance of such interaction to infection. Maintenance of the outer membrane lipid asymmetry may play an essential role in NTHi barrier function and interaction with hydrophobic molecules. VacJ/MlaA-MlaBCDEF prevents phospholipid accumulation at the bacterial surface, being the only system involved in maintaining membrane asymmetry identified in NTHi. We assessed the relationship among the NTHi VacJ/MlaA outer membrane lipoprotein, bacterial and exogenous fatty acids, and respiratory infection. The vacJ/mlaA gene inactivation increased NTHi fatty acid and phospholipid global content and fatty acyl specific species, which in turn increased bacterial susceptibility to hydrophobic antimicrobials, decreased NTHi epithelial infection, and increased clearance during pulmonary infection in mice with both normal lung function and emphysema, maybe related to their shared lung fatty acid profiles. Altogether, we provide evidence for VacJ/MlaA as a key bacterial factor modulating NTHi survival at the human airway upon exposure to hydrophobic molecules.

The long chain fatty acid transporter, MFSD2A, is essential for memory CD8+ T cell formation and maintenance

Abstract Access to nutrients is critical for an effective T cell immune response to infection. Although transporters for sugars and amino acids have previously been described in the context of the CD8+ T cell immune response, the active transport of exogenous esterified fatty acids has remained enigmatic. Here we discovered the long chain fatty acid transporter, Major Facilitator Super Family Domain Containing 2a (MFSD2A), is upregulated on activated CD8+ T cells and is essential for their memory cell formation. MFSD2A deficiency resulted in decreased import of long chain fatty acids (LCFAs) esterified to lysophosphatidylcholine (LPC) into activated CD8+ T cells but overall resulted in a normal primary effector T cell response. However, loss of MFSD2A led to reduced memory T cell formation and maintenance. MFSD2A deficient memory CD8+ T cells showed reduced CD127 and CD62L expression and their cell turnover was significantly impaired in contrast to their wildtype counterparts. Moreover, the secondary response to infection was severely diminished in MFSD2A deficient T cells. Mechanistically, import of LCFAs was required to maintain cell energy requirements and ‘fitness’, that when lost resulted in a decreased memory T cell pool and inability to proliferate upon secondary stimulation. Our results show that MFSD2A and LPC may be useful for future small molecule therapy design to generate a more robust T cell response for new vaccines or cancer treatments.

Exogenous fatty acids alter phospholipid composition, membrane permeability, capacity for biofilm formation, and antimicrobial peptide susceptibility in Klebsiella pneumoniae.

Klebsiella pneumoniae represents a major threat to human health due to a combination of its nosocomial emergence and a propensity for acquiring antibiotic resistance. Dissemination of the bacteria from its native intestinal location creates severe, complicated infections that are particularly problematic in healthcare settings. Thus, there is an urgency for identifying novel treatment regimens as the incidence of highly antibiotic‐resistant bacteria rises. Recent findings have highlighted the ability of some Gram‐negative bacteria to utilize exogenous fatty acids in ways that modify membrane phospholipids and influence virulence phenotypes, such as biofilm formation and antibiotic resistance. This study explores the ability of K. pneumoniae to assimilate and respond to exogenous fatty acids. The combination of thin‐layer chromatography liquid chromatography‐mass spectrometry confirmed adoption of numerous exogenous polyunsaturated fatty acids (PUFAs) into the phospholipid species of K. pneumoniae. Membrane permeability was variably affected as determined by two dye uptake assays. Furthermore, the availability of many PUFAs lowered the MICs to the antimicrobial peptides polymyxin B and colistin. Biofilm formation was significantly affected depending upon the supplemented fatty acid.

Mutation in MON2, Which Encodes a Protein Implicated in Vesicular Transport, Affects Response to Exogenous Fatty Acids in Yeast

Metabolism of exogenous fatty acids requires cells to take up, traffic, and molecularly respond to fed fatty acids. Our lab has determined that a mutation in mon2 results in defective growth on the fatty acid 10‐undecenoic acid. Like wild type cells, mon2Δ mutants are capable of normal response to the feeding of long chain unsaturated fatty acids (UFAs) by reducing transcription of OLE1, (which encodes the Δ9 desaturase), and by reducing the accumulation of endogenously produced UFAs. However, wild type cells when fed 10‐undecenoic acid will continue to express OLE1 and increase their content of endogenously produced UFAs. In contrast, mon2Δ mutants do not differentially respond to the two fatty acids. Staining with a BODIPY‐labeled fluorescent fatty acid analog indicates that there is a difference in localization/amount of the supplied fatty acid in mon2Δ cells compared to wild type cells. Thus, it appears that the mon2 mutation decreases the cell's ability to differentiate between fatty acids, perhaps due to mislocalization of the fed fatty acid or regulatory proteins.Support or Funding InformationThis work was supported by a Jacob Nyenhuis Faculty Award (VM), NSF‐REU (AG, MS, BG) and a Summer Scholar award from the Dean for Natural and Applied Science (RD).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Cortactin's Influence on Mitochondrial Bioenergetics in the Diabetic Heart: A Novel Viewpoint

Cortactin, a protein which controls the cytoskeleton, has been suggested to impact mitochondrial function by influencing the outer mitochondrial membrane during fusion and fission. Cortactin has been shown to interact directly with Coronin 1b by affecting Arp 2/3 during actin formation and branching, but it is currently unknown how cortactin dynamics affect the structure and function of mitochondria in the heart during type 2 diabetes mellitus. The goal of the study was to visualize changes in cytoskeletal proteins in the type 2 diabetic heart, and determine whether genetic alteration of cortactin levels impacts the mitochondrion on a molecular level. We hypothesized that cytoskeletal proteins associated with mitochondrial dynamics would be significantly altered in the type 2 diabetic state, and that specific changes in cortactin would have a direct effect on mitochondrial bioenergetics and function. Western blots were utilized to visualize cortactin, coronin1b and phosphor‐coronin1b levels in type 2 diabetic human patient heart and db/db mouse cardiac tissue. Results indicated that in both type 2 diabetic human patient and db/db cardiac tissue, cortactin and coronin1b levels are dysregulated. Cortactin levels were significantly increased (P<0.05) as were coronin1b levels in db/db mouse cardiac tissue (P<0.05). Phosphorylated coronin1b was significantly decreased in human type 2 diabetic cardiac tissue (P<0.05). To determine whether increased cortactin levels observed in the type 2 diabetic state can influence the mitochondrion, we utilized an HL‐1 cardiomyocyte model in which cortactin was either knocked down or overexpressed. Mitochondria were isolated post transfection with an expression vector for cortactin and analyzed via flow cytometry for size and internal complexity, JC‐1 staining for membrane potential, electron transport chain complex activities, and bioenergetics using the Seahorse. Cortactin overexpression and knockdown significantly altered the membrane potential of the mitochondria (P<0.05). Further, in cells overexpressing cortactin, exogenous fatty acid utilization was decreased (P<0.05), and cells appeared to be completely dependent of endogenous free fatty acids (FFA) for respiration (P<0.05). Taken together, our data indicate that cortactin is significantly increased in the type 2 diabetic heart of both human patient and mouse cardiac tissue. Further, these data indicate that increased cortactin levels associated with the type 2 diabetic heart may contribute to changes in mitochondrial function by influencing membrane potential and their capacity to utilize FFA during respiration.Support or Funding InformationSupport: NIH R01 HL128485; AHA 17PRE33660333This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

IRE1α RNase-dependent lipid homeostasis promotes survival in Myc-transformed cancers.

Myc activation is a primary oncogenic event in many human cancers; however, these transcription factors are difficult to inhibit pharmacologically, suggesting that Myc-dependent downstream effectors may be more tractable therapeutic targets. Here, we show that Myc overexpression induces endoplasmic reticulum (ER) stress and engages the inositol-requiring enzyme 1α (IRE1α)/X-box binding protein 1 (XBP1) pathway through multiple molecular mechanisms in a variety of c-Myc- and N-Myc-dependent cancers. In particular, Myc-overexpressing cells require IRE1α/XBP1 signaling for sustained growth and survival in vitro and in vivo, dependent on elevated stearoyl-CoA-desaturase 1 (SCD1) activity. Pharmacological and genetic XBP1 inhibition induces Myc-dependent apoptosis, which is alleviated by exogenous unsaturated fatty acids. Of note, SCD1 inhibition phenocopies IRE1α RNase activity suppression in vivo. Furthermore, IRE1α inhibition enhances the cytotoxic effects of standard chemotherapy drugs used to treat c-Myc-overexpressing Burkitt's lymphoma, suggesting that inhibiting the IRE1α/XBP1 pathway is a useful general strategy for treatment of Myc-driven cancers.

Adipocyte-induced CD36 expression drives ovarian cancer progression and metastasis.

Ovarian cancer (OvCa) is characterized by widespread and rapid metastasis in the peritoneal cavity. Visceral adipocytes promote this process by providing fatty acids (FAs) for tumour growth. However, the exact mechanism of FA transfer from adipocytes to cancer cells remains unknown. This study shows that OvCa cells co-cultured with primary human omental adipocytes express high levels of the FA receptor, CD36, in the plasma membrane, thereby facilitating exogenous FA uptake. Depriving OvCa cells of adipocyte-derived FAs using CD36 inhibitors and short hairpin RNA knockdown prevented development of the adipocyte-induced malignant phenotype. Specifically, inhibition of CD36 attenuated adipocyte-induced cholesterol and lipid droplet accumulation and reduced intracellular reactive oxygen species (ROS) content. Metabolic analysis suggested that CD36 plays an essential role in the bioenergetic adaptation of OvCa cells in the adipocyte-rich microenvironment and governs their metabolic plasticity. Furthermore, the absence of CD36 affected cellular processes that play a causal role in peritoneal dissemination, including adhesion, invasion, migration and anchorage independent growth. Intraperitoneal injection of CD36-deficient cells or treatment with an anti-CD36 monoclonal antibody reduced tumour burden in mouse xenografts. Moreover, a matched cohort of primary and metastatic human ovarian tumours showed upregulation of CD36 in the metastatic tissues, a finding confirmed in three public gene expression datasets. These results suggest that omental adipocytes reprogram tumour metabolism through the upregulation of CD36 in ovarian cancer cells. Targeting the stromal-tumour metabolic interface via CD36 inhibition may prove to be an effective treatment strategy against OvCa metastasis.

Serum Albumin's Protective Inhibition of Amyloid-β Fiber Formation Is Suppressed by Cholesterol, Fatty Acids and Warfarin

Central to Alzheimer's disease (AD) pathology is the assembly of monomeric amyloid-β peptide (Aβ) into oligomers and fibers. The most abundant protein in the blood plasma and cerebrospinal fluid is human serum albumin. Albumin can bind to Aβ and is capable of inhibiting the fibrillization of Aβ at physiological (μM) concentrations. The ability of albumin to bind Aβ has recently been exploited in a phase II clinical trial, which showed a reduction in cognitive decline in AD patients undergoing albumin–plasma exchange. Here we explore the equilibrium between Aβ monomer, oligomer and fiber in the presence of albumin. Using transmission electron microscopy and thioflavin-T fluorescent dye, we have shown that albumin traps Aβ as oligomers, 9 nm in diameter. We show that albumin-trapped Aβ oligomeric assemblies are not capable of forming ion channels, which suggests a mechanism by which albumin is protective in Aβ-exposed neuronal cells. In vivo albumin binds a variety of endogenous and therapeutic exogenous hydrophobic molecules, including cholesterol, fatty acids and warfarin. We show that these molecules bind to albumin and suppress its ability to inhibit Aβ fiber formation. The interplay between Aβ, albumin and endogenous hydrophobic molecules impacts Aβ assembly; thus, changes in cholesterol and fatty acid levels in vivo may impact Aβ fibrillization, by altering the capacity of albumin to bind Aβ. These observations are particularly intriguing given that high cholesterol or fatty acid diets are well-established risk factors for late-onset AD.

The becoming of reactions of lipolysis in phylogenesis. The palmitic and oleic triglycerides as substrates. Insulin, condition of normolipemia and formation of hyper lipoproteinemia type IIb, IV and V

According to phylogenetic theory of general pathology, when living in ocean all were carnivorous (piscivorous) fatty acids transferring to cells in form of non-polar triglycerides nitially began apoB-48 chylomicrons, continued lipoproteins of very low and low density and fnalized its apoB-100 endocytosis. The fatty acids are transferred by chylomicrons + lipoproteins of very low density + lipoproteins of low density and non-polar triglycerides are hydrolyzed by hepatic glycerolhydrogenase and co-enzyme apoC-III; according WHO classifcation, hyperlipoproteinemia corresponds to type V. On land, in herbivorous who are not yet synthesized insulin, apoB-48 and chylomicrons left process of non-polar triglycerides transferring. In lipoproteins of very low density and lipoproteins of low density, the carnivorous transfer exogenous palmitic non-polar triglycerides. The herbivorous also transfer palmitic non-polar triglycerides though synthesized by hepatocytes from glucose endogenically. In herbivorous, transferring of palmitic non-polar triglycerides prior to synthesis of insulin is forming apoB-100 in composition of lipoproteins of very low density and lipoproteins of low density. The hydrolysis of palmitic non-polar triglycerides in lipoproteins of very low density is activated by hepatic glycerol hydrogenase and apoC-III; cells absorb lipoproteins of low density by means of apoB-100 endocytosis. The content on lipoproteins in blood plasma under electrophoresis of lipoproteins corresponds to hepatic glycerol hydrogenase type IIb. In frst and second types of fatty acids transferring in form of triglycerides to lipoproteins of very low density + lipoproteins of low density predominate palmitic fatty acid, triglycerides of the same name and palmitic metabolism of fatty acids in vivo. The insulin initiated the third type of transferring of oleic fatty acid by now to insulin-depended cells only in oleic lipoproteins of very low density; hydrolysis of oleic triglycerides is activated by late in phylogenesis post-heparin hepatic glycerol hydrogenase and apoC-II cofactor. The dynamic apoE is actively bound by apoB-100 forming apoE/B-100 ligand. At later stages of phylogenesis insulin formed fatty acids transferring in form of oleic triglycerides in lipoproteins of very low density of the same name without forming of oleic lipoproteins of low density; the electrophoregram of lipoproteins reflects absence of hepatic glycerol hydrogenase. In phylogenesis three types of fatty acids transferring to triglycerides in composition of lipoproteins formed sequentially: 1) chylomicrons + lipoproteins of very low and density + lipoproteins of low density; 2) lipoproteins of very low density + lipoproteins of low density; 3) only in lipoproteins of very low density. The frst one is specifc to piscivorous (carnivorous) while living in ocean. The second one is implemented by herbivorous while they didn't begin to synthesize insulin and hepatocytes not yet transform all endogenous palmitic fatty acid into oleic fatty acid. Insulin initiated: a) transferring of oleic fatty acids to lipoproteins of very low density without forming oleic lipoproteins of low density; b) highly effective oleic metabolism of fatty acids in vivo: c) becoming of biological function of locomotion. The aphysiological induction by substrate, surplus of palmitic fatty acids in food initiate negative alterations in composition of lipoproteins in opposite direction than in case of phylogenesis. When homo sapiens, herbivorous in phylogenesis, begins to misuse carnivorous (meat) food then instead of normolipoproteinemia in blood plasma under electrophoresis of lipoproteins one can initially detect transitory hyperlipoproteinemia type IV and then prolonged hyperlipoproteinemia type IIb. If patient factually passes on to carnivorous diet then hyperlipoproteinemia type V is developing. If content of exogenous palmitic fatty acid in food surpasses physiological capacities of its transferring in oleic triglycerides as palmitoyl-oleyl-palmitate glycerol, palmitic triglycerides as oleyl-palmitoyl-palmitate glycerol begin to form and epigenetically aphysiological non-ligand palmitic lipoproteins of very low density → lipoproteins of low density are formed. Their circulation in blood is a cause of hypertriglyceridemia, higher level of cholesterol-lipoproteins of low density, compensatory increasing of apoC-III. Then occurs induced by substrate formation of hyperlipoproteinemia initially of type IV, then of type IIb and fnally of type V. The pathogenesis of atherosclerosis and atheromotosis is activated when homo sapiens, herbivorous in phylogenesis, begin to misuse carnivorous food affecting biological functions of trophology, reaction of exotrophy (external nutrition), function of homeostasis, endoecology and function of adaptation. The formation of palmitic metabolism if fatty acids instead of oleic one is a cause of chronic defciency of energy and ATP synthesis in vivo. Insulin activates absorption of glucose by cells with purpose to use it for synthesis of oleic fatty acids. In the frst place, insulin regulates in vivo metabolism of fatty acids and only in second place metabolism of glucose.

Formation in the phylogenesis of three pulls of cells with expressed different absorption and metabolism of fatty acids. Insulin and medium chains fatty acids.

Somatic cells at the early stages of phylogenesis realized the metabolism of long-chain fatty acids (FA), primarily palmitic saturated FA. It dominated the construction of a bilayer cell membrane and as a substrate for oxidation in mitochondria during energy production. Later, polyene FAs became involved in the construction of the cell membrane, the membranes of intracellular organelles, and became the substrate for the synthesis of biologically active eicosanoids. At later stages of phylogenesis, the metabolism of medium-chain FAs is activated and the formation of ketone bodies as a substrate, which is available for oxidation by the mitochondria of the formed cells of the nervous tissue in the absence of first substrate glucose. In the later stages of phylogenesis, insulin initiated: a) the transformation of carnivorous ancestors of the species Homo sapiens in the ocean into a herbivorous species while living on land; b) the formation of the new biological function of locomotion and c) the dominance of the oleic variant of the metabolism of long-chain fatty acids with higher kinetic parameters of mitochondria oxidation. Metabolites of medium chain FA have become humoral mediators of metabolism and the formation of feedback mechanisms in the function of trophology and cognitive biological function. The formation of an oleic variant of the metabolism of fatty acids under the action of insulin led to the improvement of the energy supply of cells and the high kinetic parameters of many species of herbivorous mammals, including Homo sapiens. The species Homo sapiens was not omnivorous (Omnivores); the insulin's regulatory action during life on land has turned it into a herbivorous species (Herbivore), but with a carnivorous (Carnivore) (fish-eating) past. Seven metabolic pandemics (1. atherosclerosis and atheromatosis; 2. metabolic arterial hypertension; 3. metabolic syndrome; 4. insulin resistance syndrome; 5. obesity; 6. nonalcoholic fatty liver disease and 7. endogenous hyperuricemia) are only functional disorders and can be, in most cases, eliminated. From the standpoint of the phylogenetic theory of general pathology, atherosclerosis and atheromatosis of the arteries have no great future. As soon, as the majority of individuals of the Homo sapiens species realize that in phylogenesis they have formed as herbivores and stop eating excessive amounts of meat food, exogenous palmitic FA, the incidence in the population will begin to decrease. Patients are still obliged to justify the binary, biological name of the species - reasonable man. Prevention and other metabolic pandemics, diseases of civilization, can be discussed. It takes time, an understanding of what happens by the doctors, diligence and the desire of patients to be healthy.

B1a B cells require autophagy for metabolic homeostasis and self-renewal.

Specific metabolic programs are activated by immune cells to fulfill their functional roles, which include adaptations to their microenvironment. B1 B cells are tissue-resident, innate-like B cells. They have many distinct properties, such as the capacity to self-renew and the ability to rapidly respond to a limited repertoire of epitopes. The metabolic pathways that support these functions are unknown. We show that B1 B cells are bioenergetically more active than B2 B cells, with higher rates of glycolysis and oxidative phosphorylation, and depend on glycolysis. They acquire exogenous fatty acids and store lipids in droplet form. Autophagy is differentially activated in B1a B cells, and deletion of the autophagy gene Atg7 leads to a selective loss of B1a B cells caused by a failure of self-renewal. Autophagy-deficient B1a B cells down-regulate critical metabolic genes and accumulate dysfunctional mitochondria. B1 B cells, therefore, have evolved a distinct metabolism adapted to their residence and specific functional properties.

Lipid raft localization of TLR2 and its co-receptors is independent of membrane lipid composition.

BackgroundToll like receptors (TLRs) are an important and evolutionary conserved class of pattern recognition receptors associated with innate immunity. The recognition of Gram-positive cell wall constituents strongly depends on TLR2. In order to be functional, TLR2 predominantly forms a heterodimer with TLR1 or TLR6 within specialized membrane microdomains, the lipid rafts. The membrane lipid composition and the physicochemical properties of lipid rafts are subject to modification by exogenous fatty acids. Previous investigations of our group provide evidence that macrophage enrichment with polyunsaturated fatty acids (PUFA) induces a reordering of lipid rafts and non-rafts based on the incorporation of supplemented PUFA as well as their elongation and desaturation products.MethodsIn the present study we investigated potential constraining effects of membrane microdomain reorganization on the clustering of TLR2 with its co-receptors TLR1 and TLR6 within lipid rafts. To this end, RAW264.7 macrophages were supplemented with either docosahexaenoic acid (DHA) or arachidonic acid (AA) and analyzed for receptor expression and microdomain localization in context of TLR stimulation.Results and ConclusionsOur analyses showed that receptor levels and microdomain localization were unchanged by PUFA supplementation. The TLR2 pathway, in contrast to the TLR4 signaling cascade, is not affected by exogenous PUFA at the membrane level.

Improvement of non-alcoholic steatohepatitis by hepatocyte-like cells generated from iPSCs with Oct4/Sox2/Klf4/Parp1.

The prevalence of nonalcoholic fatty liver disease (NAFLD) is usually increased with age. Non-alcoholic steatohepatitis (NASH), a serious form of NAFLD, may lead to cirrhosis and end-stage liver diseases. Induced pluripotent stem cells (iPSCs) hold promising potential in personalized medicine. Although obviation of c-Myc reduces tumorigenic risk, it also largely reduced the generation of iPSCs. Recently, Poly(ADP-ribose) polymerase 1 (Parp1) has been reported to enhance cell reprogramming. In this study, we demonstrated that forced expression of Oct4/Sox2/Klf4/Parp1 (OSKP) effectively promoted iPSC generation from senescent somatic cells from 18-month-old mouse. The iPSCs presented regular pluripotent properties, ability to form smaller teratoma with smaller size, and the potential for tridermal differentiation including hepatocyte-like cells (OSKP-iPSC-Heps). Resembled to fetal hepatocytes but not senescent hepatocytes, these OSKP-iPSC-Heps possessed antioxidant ability and were resistant to oxidative insult induced by H2O2 or exogenous fatty acid. Intrasplenic transplantation of OSKP-iPSC-Heps ameliorated the triglyceride over-accumulation and hepatitis, prevented the production of inflammatory cytokines and oxidative substances, and reduced apoptotic cells in methionine/choline-deficient diet (MCDD)-fed mice. In conclusion, we demonstrated that Parp-1 promoted iPSC generation from senescent cells, which can be used for the treatment of NASH after hepatic-specific differentiation. These findings indicated that patient-derived iPSC-Heps may offer an alternative option for treatment of NASH and NASH-associated end-stage liver diseases.