Lipid-related Pathways Research Articles

Genetic variants from lipid-related pathways and risk for incident myocardial infarction.

BackgroundCirculating lipids levels, as well as several familial lipid metabolism disorders, are strongly associated with initiation and progression of atherosclerosis and incidence of myocardial infarction (MI).ObjectivesWe hypothesized that genetic variants associated with circulating lipid levels would also be associated with MI incidence, and have tested this in three independent samples.Setting and SubjectsUsing age- and sex-adjusted additive genetic models, we analyzed 554 single nucleotide polymorphisms (SNPs) in 41 candidate gene regions proposed to be involved in lipid-related pathways potentially predisposing to incidence of MI in 2,602 participants of the Swedish Twin Register (STR; 57% women). All associations with nominal P<0.01 were further investigated in the Uppsala Longitudinal Study of Adult Men (ULSAM; N = 1,142).ResultsIn the present study, we report associations of lipid-related SNPs with incident MI in two community-based longitudinal studies with in silico replication in a meta-analysis of genome-wide association studies. Overall, there were 9 SNPs in STR with nominal P-value <0.01 that were successfully genotyped in ULSAM. rs4149313 located in ABCA1 was associated with MI incidence in both longitudinal study samples with nominal significance (hazard ratio, 1.36 and 1.40; P-value, 0.004 and 0.015 in STR and ULSAM, respectively). In silico replication supported the association of rs4149313 with coronary artery disease in an independent meta-analysis including 173,975 individuals of European descent from the CARDIoGRAMplusC4D consortium (odds ratio, 1.03; P-value, 0.048).Conclusionsrs4149313 is one of the few amino acid changing variants in ABCA1 known to associate with reduced cholesterol efflux. Our results are suggestive of a weak association between this variant and the development of atherosclerosis and MI.

291 THE USE OF THE DYNAMIC IMPACT APPROACH AND DESORPTION ELECTROSPRAY IONIZATION - MASS SPECTROSCOPY TO ANALYZE ADIPOGENESIS IN PORCINE ADIPOSE-DERIVED STEM CELLS

The measurement of end products of metabolism in combination with the dynamic measurement of the transcriptome can be a valuable approach to study complex processes, such as adipogenesis. For this purpose, we have combined the analysis of metabolic pathways using transcriptomics data with in situ lipid imaging obtained by desorption electrospray ionization–mass spectroscopy (DESI-MS). The transcriptome data was obtained from a previous experiment where adipose-derived stem cells (ASC) from 3 individual pigs were induced to differentiate into adipocytes for 21 days. The metabolic pathway analysis of transcriptomics data was performed using the dynamic impact approach (DIA) to determine the directional impact of pathways and gene categories. For the DESI-MS, porcine ASC were induced towards adipogenic differentiation (Monaco et al. 2009 Open Tissue Eng. Regen. Med. J. 2, 20–33) for 2 weeks in 24-well plates over round coverslips. Direct lipid profile of fatty acids and phospholipids in 3 different locations in undifferentiated and differentiated ASC was performed. Relative values of ion counts in each location were used for statistical analysis by means of a two-tailed t-test with unequal variance and false discovery rate (FDR) correction. The DIA uncovered amino acid and lipid metabolism as being the most affected pathways during adipogenesis. Among lipid-related pathways, the DIA indicated a strong induction during differentiation of unsaturation of fatty acids (FA) and metabolism of lipids, particularly triacylglycerol formation (TAG). The metabolism of tryptophan, phenylalanine, and histidine was strongly induced among amino acid-related metabolism. Among the lipid molecules identified in the mass-to-charge ratio (m/z) range of 250–1000 by the DESI-MS, &gt;200 had significantly (FDR &lt;0.01) lower abundance and ~30 lipids had higher abundance in differentiated compared with undifferentiated ASC. The lipid profile of undifferentiated cells was featured by a large amount of lipid molecules in the lower (m/z 780) mass range but with almost no signal in the intermediate range. The differentiated cells had a consistent large increase in amount of molecules in the range from m/z 500 to 650 and a decreased amount in the lower and upper ranges. Among the lipid molecules that decreased during differentiation, we identified several phospholipids, particularly phosphoserine and phosphoinositol species, but also linoleic, linolenic, arachidic, and eicosapentaenoic acids. The unsaturated FA oleate and docosahexaenate increased &gt;10-fold and 2.2-fold, respectively, due to adipogenic differentiation. High-resolution experiments are being performed in order to annotate more, if not all, lipid species identified in the samples by DESI-MS. The DIA indicated greater unsaturation of FA during adipogenesis, confirmed by DESI-MS, which corresponds to the characteristic increase in lipid fractions with intermediate molecular mass. This can be considered a signature of adipogenesis in porcine ASC and essential for TAG formation. The DESI-MS appears to be a valuable tool for rapid lipid profile of cells and with the potential to be used to identify cell differentiation.

Insulin Sensitivity Is Reflected by Characteristic Metabolic Fingerprints - A Fourier Transform Mass Spectrometric Non-Targeted Metabolomics Approach

BackgroundA decline in body insulin sensitivity in apparently healthy individuals indicates a high risk to develop type 2 diabetes. Investigating the metabolic fingerprints of individuals with different whole body insulin sensitivity according to the formula of Matsuda, et al. (ISIMatsuda) by a non-targeted metabolomics approach we aimed a) to figure out an unsuspicious and altered metabolic pattern, b) to estimate a threshold related to these changes based on the ISI, and c) to identify the metabolic pathways responsible for the discrimination of the two patterns.Methodology and Principal FindingsBy applying infusion ion cyclotron resonance Fourier transform mass spectrometry, we analyzed plasma of 46 non-diabetic subjects exhibiting high to low insulin sensitivities. The orthogonal partial least square model revealed a cluster of 28 individuals with alterations in their metabolic fingerprints associated with a decline in insulin sensitivity. This group could be separated from 18 subjects with an unsuspicious metabolite pattern. The orthogonal signal correction score scatter plot suggests a threshold of an ISIMatsuda of 15 for the discrimination of these two groups. Of note, a potential subgroup represented by eight individuals (ISIMatsuda value between 8.5 and 15) was identified in different models. This subgroup may indicate a metabolic transition state, since it is already located within the cluster of individuals with declined insulin sensitivity but the metabolic fingerprints still show some similarities with unaffected individuals (ISI >15). Moreover, the highest number of metabolite intensity differences between unsuspicious and altered metabolic fingerprints was detected in lipid metabolic pathways (arachidonic acid metabolism, metabolism of essential fatty acids and biosynthesis of unsaturated fatty acids), steroid hormone biosyntheses and bile acid metabolism, based on data evaluation using the metabolic annotation interface MassTRIX.ConclusionsOur results suggest that altered metabolite patterns that reflect changes in insulin sensitivity respectively the ISIMatsuda are dominated by lipid-related pathways. Furthermore, a metabolic transition state reflected by heterogeneous metabolite fingerprints may precede severe alterations of metabolism. Our findings offer future prospects for novel insights in the pathogenesis of the pre-diabetic phase.

Conjugated Linoleic Acid Activates AMP-Activated Protein Kinase and Reduces Adiposity More Effectively When Used with Metformin in Mice1–3

Trans-10, cis-12 (t10c12) conjugated linoleic acid (CLA) reduces lipid levels in adipocytes, but the mechanisms involved are still emerging. The hypotheses of this study were that t10c12 CLA treatment activated AMP-activated protein kinase (AMPK) and that the effectiveness of a low dose of t10c12 CLA would be increased when combined with an AMPK activator. We demonstrated t10c12 CLA, directly or indirectly, activated AMPK and increased the amount of phosphorylated acetyl-CoA carboxylase (ACC) in 3T3-L1 adipocytes. Compound C, a potent inhibitor of AMPK, attenuated the phosphorylation of ACC, integrated stress response (ISR), inflammatory response, reduction in key lipogenic transcription factors, and triglyceride (TG) reduction that otherwise occurred in t10c12 CLA-treated adipocytes. Treatment of adipocytes or mice with a low dose of t10c12 CLA in conjunction with the AMPK activator metformin resulted in more TG loss than treatment with the individual chemicals. Additionally, although an inflammatory response was required for robust TG reduction, the combination of t10c12 CLA with AMPK activators had a similar TG loss with a reduced inflammatory response. A microarray analysis of the transcriptional response to either t10c12 CLA, metformin, or the combination, indicated the responses were very similar, with a correlation coefficient of 0.91 or better for genes in the ISR or lipid-related pathways. Altogether, these results support our hypotheses that t10c12 CLA activates AMPK, directly or indirectly, and that metformin increases the effectiveness of t10c12 CLA in reducing TG amounts in adipocytes.

Major impacts on the primary metabolism of the plant pathogen Cryphonectria parasitica by the virulence-attenuating virus CHV1-EP713

Cryphonectria parasitica, the chestnut blight fungus, can be infected by virulence-attenuating mycoviruses of the family Hypoviridae. Previous studies have led to the hypothesis that the hypovirus-infected phenotype is partly due to metabolic changes induced by the viral infection. To investigate this, we measured the metabolic rate and respiration of C. parasitica colonies grown on solid medium. These experiments supported historical observations of other fungal species done in liquid cultures that the metabolic rate steadily declines with age and differentiation of the mycelium. Hypovirus infection increased metabolic rate in the youngest mycelium, but a subsequent decline was also observed as the mycelium aged. By measuring both CO(2) production and O(2) consumption, we also observed that changes occur in carbohydrate metabolism as a result of ageing in both infected and uninfected mycelium. Mycelium on the periphery of the colony exploited fermentation pathways extensively, before transitioning to aerobic carbohydrate metabolism and finally lipid metabolism in the interior regions, despite abundant remaining glucose. However, the hypovirus affected the extent of these changes, with infected mycelium apparently unable to utilize lipid-related metabolic pathways, leading to an increased depletion of glucose. Finally, we used metabolic profi fi ling to determine the changes in accumulation of primary metabolites in wild-type and hypovirus-infected mycelium and found that approximately one-third of the 164 detected metabolites were affected. These results are consistent with those expected from the physiological measurements, with significant alterations noted for compounds related to lipid and carbohydrate metabolism. Additionally, we observed an increase in the accumulation of the polyamine spermidine in the presence of hypovirus. Polyamines have been implicated in antiviral responses of mammalian systems; therefore this may suggest a novel antiviral response mechanism in fungi.

Apolipoprotein‐D expression is increased during development and maturation of the human prefrontal cortex

Apolipoprotein D (apoD) is a lipid binding protein expressed in the brain where its function is largely unknown. Based on changes in lipid metabolism and deposition that occur in the human brain during postnatal development, we investigated changes in apoD expression in the prefrontal cortex in 69 normal cases ranging in age from 40 days to 49 years utilizing gene microarray, quantitative PCR and western blotting methods. In contrast to the high expression of apolipoprotein E (APOE), low-density lipoprotein receptor-related protein 8 (LRP8) and 3-hydroxy-3-methyl-glutaryl-CoA reducatase (HMGCR) (genes that play a role in lipid-related pathways in brain development) early in life, apoD expression was low in neonates and increased in expression throughout life resulting in six- to eight-fold higher levels at the mRNA and protein levels in adults. Recent studies suggest that apoD has a novel antioxidant function in the brain and we found that the increased apoD expression throughout development and into adulthood was correlated with the expression of antioxidant genes superoxide dismutase 1 (SOD1) and glutathione peroxidase 3 (GPX3) as well as proteins that were modified by the lipid peroxidation end-product 4-hydroxynonenal. These studies reveal that apoD expression is increased throughout life in the human prefrontal cortex and that this is correlated with genetic and biochemical markers of oxidative stress.

The Edinburgh human metabolic network reconstruction and its functional analysis

A better understanding of human metabolism and its relationship with diseases is an important task in human systems biology studies. In this paper, we present a high-quality human metabolic network manually reconstructed by integrating genome annotation information from different databases and metabolic reaction information from literature. The network contains nearly 3000 metabolic reactions, which were reorganized into about 70 human-specific metabolic pathways according to their functional relationships. By analysis of the functional connectivity of the metabolites in the network, the bow-tie structure, which was found previously by structure analysis, is reconfirmed. Furthermore, the distribution of the disease related genes in the network suggests that the IN (substrates) subset of the bow-tie structure has more flexibility than other parts.

Inhibition of ChoK Is an Efficient Antitumor Strategy for Harvey-, Kirsten-, and N-ras-Transformed Cells

An increasing amount of evidence suggests that elevated PCho levels are related to the transforming properties of the H-Ras oncoprotein. Based on these observations, we have designed an antitumor strategy using choline kinase, the enzyme responsible of PCho production, as a novel target for drug discovery. However, little relationship between this lipid-related pathway and the other two Ras members, N- and K-ras, has been established. Since N- and K-ras are the most frequently mutated ras genes in human tumors, we have analyzed the PC-PLD/ChoK pathway and the sensitivity to ChoK inhibition of all three ras-transformed cells. Here we demonstrate that transformation by the three Ras oncoproteins results in increased levels of PCho to a similar extent, resulting from a similar constitutive increase of ChoK activity. As well, sensitivity to choline kinase inhibitors as antiproliferative drugs is similar in cell lines transformed by each of the three ras oncogenes, being in all cases higher than parental, nontransformed cells. In addition, H, K and N-ras-induced alterations in PC metabolism is discussed. These results indicate that ChoK can be used as a general target for anticancer drug design against Ras-dependent tumorigenesis.

Simple method for measuring oxygen consumption in babies.

A simple open-circuit method for measuring the rate of oxygen consumption in the neonatal nursery is described and preliminary results on 240 infants reported. The findings are consistent with previous studies using closed systems and artificial environments. The variation between one infant and another was great, which makes it difficult to predict for any one infant the thermal environment at which the rate of oxygen consumption will be minimal.