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Integrated Omic Analysis of a Guinea Pig Model of Heart Failure and Sudden Cardiac Death

ABSTRACT: Sudden cardiac death (SCD) associated with heart failure (HF) is a multifactorial problem requiring a systems level approach applied to suitable experimental animal models with features of the human disease. Here we examine key regulatory pathways underlying the transition from compensated hypertrophy (HYP) to decompensated HF and SCD by integrated analysis of the transcriptome, proteome and metabolome. In a guinea pig model of acquired long QT syndrome and HF/SCD, relative protein abundances from sham-operated, HYP and HF hearts were assessed using isobaric tags for relative and absolute quantification (iTRAQ), prior to liquid chromatography and tandem mass spectrometry (LC-MS/MS). Metabolites were quantified by LC-MS/MS or gas chromatography coupled to MS (GC-MS). Transcriptome profiles were obtained using DNA microarrays. The guinea pig HF proteome exhibited classic biosignatures of cardiac HYP, left ventricular dysfunction, fibrosis, cellular degeneration, inflammation and extravasation. Fatty acid metabolism, mitochondrial transcription/translation factors, antioxidant enzymes, and other mitochondrial processes, were downregulated in HF, but not HYP. Proteins upregulated in HF are consistent with extracellular matrix remodeling, cytoskeletal remodeling, and acute phase inflammation markers. Among metabolites, downregulation of acyl-carnitines was observed in HYP, while fatty acids accumulated in HF. Levels of the tricarboxylic acid (TCA) cycle metabolite, citrate, and the potent inhibitor, 2-methylcitrate, increased upon transition from HYP to HF. Correlation of the magnitude of transcript and protein changes in HF is weak (R2=0.23), indicating that targeting transcript/proteome may reveal inform post-transcriptional gene regulation in HF. Proteome/Metabolome integration suggests metabolic bottlenecks in fatty acyl-CoA processing by carnitine palmitoyl transferase (CPT1B) as well as TCA cycle inhibition. We present a model in which hallmarks of acute signaling in HF, including Ca2+ dysregulation and low cAMP levels, are coupled to mitochondrial metabolic and antioxidant defects, through a CREB/PGC1-alpha transcriptional axis.

ORGANISM(S): Cavia porcellus

PROVIDER: GSE78077 | GEO | 2016/12/02

SECONDARY ACCESSION(S): PRJNA312537

REPOSITORIES: GEO

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Project description:Here we examine key regulatory pathways underlying the transition from compensated hypertrophy (HYP) to decompensated heart failure (HF) and sudden cardiac death (SCD) in a guinea pig model by integrated multi-ome analysis. Relative protein abundances from sham-operated, HYP and HF hearts were assessed by iTRAQ shotgun LC-MS/MS. Metabolites were quantified by LC-MS/MS or GC-MS. Transcriptome profiles were obtained using DNA microarrays. The guinea pig HF proteome exhibited classic biosignatures of cardiac HYP, left ventricular dysfunction, fibrosis, inflammation and extravasation. Fatty acid metabolism, mitochondrial transcription/translation factors, antioxidant enzymes, and other mitochondrial processes, were downregulated in HF, but not HYP. Proteins upregulated in HF implicate extracellular matrix remodeling, cytoskeletal remodeling, and acute phase inflammation markers. Among metabolites, downregulation of acyl-carnitines was observed in HYP, while fatty acids accumulated in HF. Correlation of transcript and protein changes in HF is weak (R2=0.23), suggesting transcript/proteome divergence may reveal post-transcriptional gene regulation in HF. Proteome/Metabolome integration suggests metabolic bottlenecks in fatty acyl-CoA processing by carnitine palmitoyl transferase (CPT1B) as well as TCA cycle inhibition. We present a model by which acute signaling in HF, including Ca2+ dysregulation and low cAMP levels, is coupled to mitochondrial metabolic and antioxidant defects, through a CREB/PGC1 transcriptional axis. Animal Model The guinea pig model of heart failure and sudden cardiac death has been described previously. Briefly, the HF and SCD guinea pig model was produced by combining ascending aortic constriction (AC) and daily isoproterenol challenge (ACi model). Specifically, Hartley guinea pigs (~250 g; Hilltop Lab Animals) were anesthetized with 4% isoflurane in a closed box for 4min, and then intubated and ventilated with oxygen and 2% isoflurane. Ascending aortic constriction (AC) was produced by tying a suture around the ascending aorta using an 18‐gauge needle as a spacer, which was then removed. For sham operations the procedure was identical though the suture was not tied. After the procedure, bupronex (0.05 mg/kg) was administered via intramuscular injection for analgesia and animals were observed until full recovery. Isoproterenol was administered daily by intra peritoneal injection at 1 mg/kg for the first week after surgery and at 2 mg/kg for a subsequent 3 weeks. As characterized previously (1), cardiac function of ACi animal is well compensated in the first 2 weeks (HYP) but declined rapidly thereafter (HF). Hypertrophic heart was collected between 1-2 weeks post-surgery (ACi-2w), whereas failing heart was collected at 4 weeks after surgery (ACi-4w). Following retrograde perfusion with 20ml Tyrode’s solution, excised hearts were Snap-frozen in liquid N2 and stored at -80°C Experimental Design The experiment consisted of 3 treatment groups: 1) HYP (ACi-2wk), 2) HF (ACi-4wk) 3) sham-operated animals with daily administration for 4 weeks (Shami-4w). 1 heart from each group was included in an iTRAQ 4-plex experiment wherein peptides from each heart are subjected to reaction with an isobaric label. The experiment was repeated twice, yielding a total of 3 independent experiments quantifying the peptides from 9 hearts. ITRAQ reagents were shuffled among treatment groups for each experiment to minimize labeling bias.

Project description:Elevated circulating lipid levels are known risk factors for cardiovascular diseases (CVD). In order to examine the effects of quercetin on hepatic lipid metabolism and detailed serum lipid profiles, mice received a mild-high-fat diet without (control) or with supplementation of 0.33% (w/w) quercetin for 12 weeks. Gas chromatography and 1H nuclear magnetic resonance were used to measure quantitatively serum lipid profiles and whole genome microarray analysis was used to identify the responsible mechanisms in liver. There were no significant differences found in mean body weight, energy intake and hepatic lipid accumulation between the quercetin and control group. In serum of quercetin-fed mice, TG levels were decreased with 15%, poly unsaturated fatty acids (PUFA) were increased with 14% and saturated fatty acids were decreased. Palmitic acid, oleic acid, and linoleic acid were all decreased in quercetin-fed mice by 9-15%. Both palmitic acid and oleic acid can be oxidized by omega-oxidation. Indeed, gene expression profiling showed that quercetin increased hepatic lipid metabolism, especially omega-oxidation. At the gene level, this was reflected by the up regulation of cytochrome P450 (Cyp) 4a10, Cyp4a14, Cyp4a31 and Acyl-CoA thioesterase 3 (Acot3). Two relevant regulators, Cytochrome P450 oxidoreductase (Por, rate limiting for cytochrome P450s) and the transcription factor Constitutive androstane receptor (Car; official symbol Nr1i3) were also up regulated in the quercetin-fed mice. We conclude that quercetin intake increased hepatic lipid omega-oxidation and lowered corresponding circulating lipid levels, a process that may involve Por and Car, and results in a potential beneficial CVD preventive effect. Liver samples were obtained from 36 C57BL/6J male adult mice. All mice started with a three week adaptation phase, in which they were fed a mild-high-fat diet. 12 mice were sacrificed immediately after the adaptation phase (t=0). The other 24 mice received the mild-high-fat diet without (HF) or with supplementation of 0.33% (w/w) quercetin (HF-Q) for 12 weeks.

Project description:How signals from fatty acid metabolism are translated into changes in food intake remains unclear. Previously we reported that mice with a genetic inactivation of Acads (short-chain acyl-CoA dehydrogenase), encoding the enzyme responsible for mitochondrial beta-oxidation of C4-C6 short-chain fatty acids (SCFAs), shift consumption away from fat and toward carbohydrate when offered a choice. This finding demonstrated that the loss of a specific enzyme in fatty acid oxidation alters the choice of diet intake. To our knowledge, there are no reports of studies on the effects of dietary fat on the brain transcriptome in genetic models of fatty acid oxidation deficiency. The current study aimed to identify molecular mediators underlying the effects of SCFA oxidation deficiency on food intake. The current study aimed to identify molecular mediators underlying the effects of SCFA oxidation deficiency on food intake. We performed a transcriptional screen for gene expression in brain tissue of Acads-/- and Acads+/+ mice fed either high-fat (HF) or low-fat (LF) diet for 2 d. Ingenuity Pathway Analysis revealed three top-scoring pathways significantly modified by genotype or diet: oxidative phosphorylation, mitochondrial dysfunction, and CREB signaling in neurons. A comparison of statistically significant responses in HF Acads-/- vs. HF Acads+/+ (3917) and Acads+/+ HF vs. LF Acads+/+ (3879) revealed 2551 genes or approximately 65% in common between the two experimental comparisons. All but one of these genes were expressed in opposite direction with similar magnitude, demonstrating that Acads-deficient mice fed HF diet display transcriptional responses that mimic those of wildtype Acads+/+ mice fed LF diet. Intriguingly, genes involved in energy sensing and metabolism followed this pattern. Quantitative RT-PCR in hypothalamus confirmed the dysregulation of several genes in these pathways. Western blotting showed that the combination of Acads deficiency and HF diet increased hypothalamic AMP-kinase, a key protein in an energy-sensing cascade that responds to depletion of ATP. Our results suggest that the decreased beta oxidation of short-chain fatty acids in Acads-deficient mice fed HF diet produces a state of energy deficiency in the brain and that AMP-kinase is the cellular energy-sensing mechanism linking fatty acid oxidation to feeding behavior in this model.

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Integrated Omic Analysis of a Guinea Pig Model of Heart Failure and Sudden Cardiac Death

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