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Altered expression of a limited number of genes contributes to cardiac decompensation during chronic pacing in dogs

ABSTRACT: We have used chronic cardiac pacing in conscious dogs to study mechanism related to the development of dilated cardiomyopathy and the transition from compensated dysfunction (CD) to decompensated heart failure (HF). This occurs from the 3rd to 4th week of pacing with end-stage HF at 30?1 days. Keywords: disease state analysis

ORGANISM(S): Canis lupus familiaris

PROVIDER: GSE5247 | GEO | 2006/10/13

SECONDARY ACCESSION(S): PRJNA96465

REPOSITORIES: GEO

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Project description:Heart failure (HF), a major health concern worldwide, with high morbidity and mortality, renders the urgent need for new treatments. Lingguizhugan decoction (LD), a classic Chinese formula, has been clinically used to treat HF. However, the molecular mechanisms involved are not fully elucidated. In this study, we first used the experimental model of transverse aortic constriction (TAC)-induced HF in C57BL/6J mice to evaluate the therapeutic efficacy of LD. Our results showed that LD exerted protective effects against TAC-induced HF by alleviating cardiac dysfunction and cardiac dilation, which might be associated with LD’s effects on down-regulating CH-related gene and protein expression. To further reveal the potential molecular mechanisms of LD in the treatment of HF, we utilized the network pharmacology to predict the core targets and potential pathways and further utilized the transcriptomics to provide changed gene profile in the heart tissue. Our results suggested that cardiac hypertrophy signaling including AKT and MAPKs signaling pathways were significantly enriched, indicating that these pathways may be the major regulatory for LD on HF treatment. Furthermore, the protein levels in AKT-GSK3β/mTOR and MAPKs pathway were determined in both compensated and decompensated states. LD inhibited the MAPKs activation, especially, reducing phosphorylated levels of p38 from the compensated state and phosphorylated levels of ERK from the decompensated state, and the latter might depend on the regulation of AMPK by LD. Moreover, LD exerts a dual role in regulating AKT-GSK3β/mTOR/P70S6K signaling pathway, characterized by active effects in the compensated state, and inhibitory effects in the decompensated state. The regulatory effect of LD on mTOR might rely on activating AKT in the compensatory state, while might be jointly determined by AKT and AMPKαin the decompensated state. Finally, by using UPLC-QE-MS/MS analysis, we detected 62 compounds in LD extract, and found 19 of which were detected in plasma of rats. Among them, 17 bioactive compounds likely regulate AKT-GSK3β/mTOR and MAPKs signaling pathway by using bioinformatics prediction. Taken together, our study showed that LD did have a better therapeutic effect on HF via dynamically balancing AKT-GSK3β/mTOR/P70S6K pathway and MAPKs pathway. Moreover, our study also provides possible bioactive compounds responsible for LD treatment on HF.

Project description: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.

Project description:Sustained atrial tachycardia leads to multiple molecular and cellular effects collectively defined as atrial tachycardia remodeling (ATR). ATR is thought to play a major role in the self-perpetuating nature of atrial fibrillation (AF) and has been a subject of intense research in large mammalian models of AF. Recently, rodents are increasingly used to gain insight on the pathophysiology AF. However, little is known regarding the effects of rapid pacing on the atria of rats and mice mainly due to technical challenges in electrophysiological studies of unanesthetized rodents. Using an implantable device for electrophysiological studies in unanesthetized rodents we examine, on a daily basis, the effects of continuous rapid atrial pacing (RAP) for at least 4 consecutive days on the developed AF substrate of Sprague-Dawley rats and C57BL6 mice. AF induction protocol consisted 10 aggressive bursts (20 seconds, double diastolic threshold, 10 ms cycle length [CL]). This protocol failed to induce AF at baseline in both species, but repeatedly induced AF episodes in rats following 2 days of sustained RAP. Microarray study of left atrial tissue from rats exposed for 2 days to RAP (70 ms CL) vs control pacing (140 ms CL) identified 304 differentially expressed genes (155 upregulated and 149 downregulated). Real-time qt-PCR confirmed the validity of the microarray. Enrichment analysis and comparison with a dataset of atrial tissue from AF patients revealed indications of increased carbohydrate metabolism, and changes in pathways that are thought to have critical role in human AF including TGF-beta and IL-6 signaling. Among 19 commonly affected genes in comparison with human AF, downregulation of FOXP1 and upregulation of the KCNK2 gene encoding the Kir2.1 potassium channel were conspicuous finding suggesting NFAT activation. Further results in line with NFAT activation included reduced expression of MIR-26, MIR-101, which were linked to upregulation of the KCNK2 in human AF. Our results demonstrate electrophysiological evidence for AF promoting effects of RAP in rats and some important molecular similarities between the effects of RAP in large and small mammalian models. The effects of atrial tachypacing are well documented in large mammals but very little is know regarding the effects of tacypacing on the rodent atria.

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Altered expression of a limited number of genes contributes to cardiac decompensation during chronic pacing in dogs

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