Dataset Information

Obesity alters molecular and functional cardiac responses to ischemia/reperfusion and glucagon-like peptide-1 receptor agonism.

ABSTRACT: This study tested the hypothesis that obesity alters the cardiac response to ischemia/reperfusion and/or glucagon like peptide-1 (GLP-1) receptor activation, and that these differences are associated with alterations in the obese cardiac proteome and microRNA (miRNA) transcriptome. Ossabaw swine were fed normal chow or obesogenic diet for 6 months. Cardiac function was assessed at baseline, during a 30-minutes coronary occlusion, and during 2 hours of reperfusion in anesthetized swine treated with saline or exendin-4 for 24 hours. Cardiac biopsies were obtained from normal and ischemia/reperfusion territories. Fat-fed animals were heavier, and exhibited hyperinsulinemia, hyperglycemia, and hypertriglyceridemia. Plasma troponin-I concentration (index of myocardial injury) was increased following ischemia/reperfusion and decreased by exendin-4 treatment in both groups. Ischemia/reperfusion produced reductions in systolic pressure and stroke volume in lean swine. These indices were higher in obese hearts at baseline and relatively maintained throughout ischemia/reperfusion. Exendin-4 administration increased systolic pressure in lean swine but did not affect the blood pressure in obese swine. End-diastolic volume was reduced by exendin-4 following ischemia/reperfusion in obese swine. These divergent physiologic responses were associated with obesity-related differences in proteins related to myocardial structure/function (e.g. titin) and calcium handling (e.g. SERCA2a, histidine-rich Ca(2+) binding protein). Alterations in expression of cardiac miRs in obese hearts included miR-15, miR-27, miR-130, miR-181, and let-7. Taken together, these observations validate this discovery approach and reveal novel associations that suggest previously undiscovered mechanisms contributing to the effects of obesity on the heart and contributing to the actions of GLP-1 following ischemia/reperfusion.

SUBMITTER: Sassoon DJ

PROVIDER: S-EPMC5135091 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Obesity alters molecular and functional cardiac responses to ischemia/reperfusion and glucagon-like peptide-1 receptor agonism.

Sassoon Daniel J DJ Goodwill Adam G AG Noblet Jillian N JN Conteh Abass M AM Herring B Paul BP McClintick Jeanette N JN Tune Johnathan D JD Mather Kieren J KJ

Basic research in cardiology 20160527 4

This study tested the hypothesis that obesity alters the cardiac response to ischemia/reperfusion and/or glucagon like peptide-1 (GLP-1) receptor activation, and that these differences are associated with alterations in the obese cardiac proteome and microRNA (miRNA) transcriptome. Ossabaw swine were fed normal chow or obesogenic diet for 6 months. Cardiac function was assessed at baseline, during a 30-minutes coronary occlusion, and during 2 hours of reperfusion in anesthetized swine treated wi ...[more]

PMID: 27234258

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Project description:Diet induced obesity in swine was associated with altered cardiovascular functional, miR transcriptome, and proteomic response to ischemia-reperfusion. Furthermore, the GLP-1 mimetic exendin-4 altered functional, miR and protein responses differently in obese versus lean swine, demonstrating the pervasive effect of obesity on modulating cardiac response to pathophysiologies and therapeutics. This study tested the hypothesis that obesity alters the left ventricular microRNA (miR) transcriptome, proteome and functional cardiac response to ischemia-reperfusion (I/R) injury and to glucagon like peptide-1 (GLP-1) receptor activation. Ossabaw swine were fed normal chow or obesogenic diet for 6 months followed by IV infusion of either saline (vehicle) or the GLP-1 mimetic exendin-4 (Ex-4). Left ventricular pressure volume relationships were assessed under baseline conditions, during a 30-minute occlusion of the circumflex artery and during a 2 hour reperfusion period. Cardiac biopsies were obtained from normally-perfused and ischemia-reperfusion territories, and analyzed using Affymetrix 3.0 miR microarray and protein mass spectrometry. I/R was found to depress global cardiac function in lean swine (systolic pressure, end-diastolic volume). In contrast, Ex-4 therapies did not affect blood pressure in obese animals, but significantly reduced end-diastolic volume following the reperfusion period. These divergent physiologic response to regional I/R in obese vs lean hearts were associated with significantly different protein and miRNA changes. Obesity was associated with altered abundance of proteins associated with calcium handling and contractility, and with changes in miRs relating to metabolism, hypertrophy, and cell death, including the miR-15 and miR-30 families, miR-199a, and miR-214. These effects were modified differently by EX-4 treatment in lean vs obese swine. These findings suggest specific miR and proteomic differences contribute to differences in functional cardiac responses to ischemia-reperfusion injury and pharmacologic activation of GLP-1 signaling in the setting of obesity, volume, stroke volume and ejection fraction) with partial amelioration seen in Ex-4 treated animals.

Project description:Mass spectrometry (MS) techniques to globally profile protein phosphorylation in cellular systems that are relevant to physiological or pathological changes have been of significant interest in biological research. An MS-based strategy utilizing an inexpensive acetone-based peptide-labeling technique known as reductive alkylation by acetone (RABA) for quantitative phosphoproteomics was explored to evaluate its capacity. Because the chemistry for RABA labeling for phosphorylation profiling had not been previously reported, it was first validated using a standard phosphoprotein and identical phosphoproteomes from cardiac tissue extracts. A workflow was then utilized to compare cardiac tissue phosphoproteomes from mouse hearts not expressing FGF2 versus hearts expressing low-molecular-weight fibroblast growth factor-2 (LMW FGF2) to relate low-molecular-weight fibroblast growth factor-2 (LMW FGF2)-mediated cardioprotective phenomena induced by ischemia/reperfusion injury of hearts, with downstream phosphorylation changes in LMW FGF2 signaling cascades. Statistically significant phosphorylation changes were identified at 14 different sites on 10 distinct proteins, including some with mechanisms already established for LMW FGF2-mediated cardioprotective signaling (e.g., connexin-43), some with new details linking LMW FGF2 to the cardioprotective mechanisms (e.g., cardiac myosin binding protein C or cMyBPC), and also several new downstream effectors not previously recognized for cardio-protective signaling by LMW FGF2. Additionally, one of the phosphopeptides, cMyBPC/pSer-282, identified was further verified with site-specific quantification using an SRM (selected reaction monitoring)-based approach that also relies on isotope labeling of a synthetic phosphopeptide with deuterated acetone as an internal standard. Overall, this study confirms that the inexpensive acetone-based peptide labeling can be used in both exploratory and targeted quantification phosphoproteomic studies to identify and verify biologically relevant phosphorylation changes in whole tissues.

Dataset Information

Obesity alters molecular and functional cardiac responses to ischemia/reperfusion and glucagon-like peptide-1 receptor agonism.

Publications

Obesity alters molecular and functional cardiac responses to ischemia/reperfusion and glucagon-like peptide-1 receptor agonism.

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