The alpha-1A adrenergic receptor agonist A61603 reduces cardiac polyunsaturated fatty acid-Heart raw data
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ABSTRACT:
ORGANISM(S): Mus Musculus
TISSUE(S): Muscle
PROVIDER: ST000451 | MetabolomicsWorkbench |
REPOSITORIES: MetabolomicsWorkbench
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| ST000452 | MetabolomicsWorkbench
Project description:Aims: The sympathetic nervous system regulates numerous critical aspects of mitochondrial function in the heart through activation of adrenergic receptors (ARs) on cardiomyocytes. Chronic β-AR activation causes maladaptive alterations in cardiomyocyte metabolism that contribute to the pathobiology of heart failure. In contrast, mounting evidence suggests that a1-ARs, particularly the a1A subtype, are cardioprotective and may mitigate the deleterious effects of chronic β-AR activation by shared endogenous catecholamine ligands. The mechanisms through which a1A-ARs exert their cardioprotective effects remain unclear. Here we tested the hypothesis that a1A-ARs adaptively regulate cardiomyocyte oxidative metabolism in both the uninjured and failing heart.
Methods: We characterized the effects of global α1A-AR genetic deletion on mitochondrial function and metabolism in the uninjured mouse heart using high resolution respirometry, substrate-specific electron transport chain (ETC) enzyme assays, transmission electron microscopy (TEM), proteomics, and lipidomics. We then compared the effects of α1A- and β-AR agonist treatment on ETC enzyme activity and oxidative stress in vivo and in vitro. We subjected wild type and cardiomyocyte-specific α1A-KO mice to permanent left coronary artery (LCA) ligation and used RNAseq to compare the transcriptomic response. Results: We found that isolated cardiac mitochondria from mice with global α1A-AR genetic deletion (α1A-KO) had deficits in fatty acid-dependent respiration and ETC enzyme activity. TEM revealed abnormalities of mitochondrial morphology characteristic of these functional deficits. The selective α1A-AR agonist A61603 (100 ng/kg/d, 3d) enhanced fatty acid oxidation (FAO) in isolated cardiac mitochondria while increasing expression and activity of the mitochondrial trifunctional protein, a critical FAO mediator. The β-AR agonist isoproterenol enhanced oxidative stress in vitro and this adverse effect was mitigated by A61603. RNAseq revealed broad basal deficits in pathways related to mitochondria and OXPHOS in cardiomyocyte-specific α1A-KO mice; these differences were exaggerated by LCA ligation. A61603 enhanced ETC Complex I activity and protected contractile function following myocardial infarction.
Conclusions: Collectively, these novel findings position α1A-ARs as critical regulators of cardiomyocyte metabolism in the basal state and suggest that metabolic mechanisms may underlie the protective effects of α1A-AR activation in the failing heart.
2024-08-15 | PXD044591 | JPOST Repository
Project description:IntroductionAlpha-1-adrenergic receptors (α1-ARs) are G-protein coupled receptors (GPCRs) with three highly homologous subtypes (α1A, α1B, and α1D). Of these three subtypes, only the α1A and α1B are expressed in the heart. Multiple pre-clinical models of heart injury demonstrate cardioprotective roles for the α1A. Non-selective α1-AR activation promotes glycolysis in the heart, but the functional α1-AR subtype and broader metabolic effects have not been studied.ObjectivesGiven the high metabolic demands of the heart and previous evidence indicating benefit from α1A activation, we chose to investigate the effects of α1A activation on the cardiac metabolome in vivo.MethodsMice were treated for one week with a low, subpressor dose of A61603, a highly selective and potent α1A agonist. Cardiac tissue and serum were analyzed using a non-targeted metabolomics approach.ResultsWe identified previously unrecognized metabolic responses to α1A activation, most notably broad reduction in the abundance of polyunsaturated fatty acids (PUFAs) and endocannabinoids (ECs).ConclusionGiven the well characterized roles of PUFAs and ECs in inflammatory pathways, these findings suggest a possible role for cardiac α1A-ARs in the regulation of inflammation and may offer novel insight into the mechanisms underlying the cardioprotective benefit of selective pharmacologic α1A activation.
| S-EPMC5437747 | biostudies-literature
Project description:BackgroundHeart failure is accompanied by changes in cardiac metabolism characterized by reduced fatty acid (FA) utilization. However, the underlying mechanism and its causative involvement in the progression of heart failure are poorly understood. The peroxisome proliferator activated receptor-α (PPARα)/retinoid X receptor (RXR) heterodimer promotes transcription of genes involved in FA metabolism through binding to the PPAR response element, called direct repeat 1 (DR1). Silent information regulator 1 (Sirt1) is a histone deacetylase, which interacts with PPARα.Methods and resultsTo investigate the role of PPARα in the impaired FA utilization observed during heart failure, genetically altered mice were subjected to pressure overload. The DNA binding of PPARα, RXRα, and Sirt1 to DR1 was evaluated with oligonucleotide pull-down and chromatin immunoprecipitation assays. Although the binding of PPARα to DR1 was enhanced in response to pressure overload, that of RXRα was attenuated. Sirt1 competes with RXRα to dimerize with PPARα, thereby suppressing FA utilization in the failing heart. DR1 sequence analysis indicated that the typical DR1 sequence favors PPARα/RXRα heterodimerization, whereas the switch from RXRα to Sirt1 takes place on degenerate DR1s. Sirt1 bound to PPARα through a region homologous to the PPARα binding domain in RXRα. A short peptide corresponding to the RXRα domain not only inhibited the interaction between PPARα and Sirt1 but also improved FA metabolism and ameliorated cardiac dysfunction.ConclusionsA change in the heterodimeric partner of PPARα from RXRα to Sirt1 is responsible for the impaired FA metabolism and cardiac dysfunction in the failing heart.
| S-EPMC4651813 | biostudies-literature
Project description:AimsThe sympathetic nervous system regulates numerous critical aspects of mitochondrial function in the heart through activation of adrenergic receptors (ARs) on cardiomyocytes. Mounting evidence suggests that α1-ARs, particularly the α1A subtype, are cardioprotective and may mitigate the deleterious effects of chronic β-AR activation by shared ligands. The mechanisms underlying these adaptive effects remain unclear. Here, we tested the hypothesis that α1A-ARs adaptively regulate cardiomyocyte oxidative metabolism in both the uninjured and infarcted heart.MethodsWe used high resolution respirometry, fatty acid oxidation (FAO) enzyme assays, substrate-specific electron transport chain (ETC) enzyme assays, transmission electron microscopy (TEM) and proteomics to characterize mitochondrial function comprehensively in the uninjured hearts of wild type and α1A-AR knockout mice and defined the effects of chronic β-AR activation and myocardial infarction on selected mitochondrial functions.ResultsWe found that isolated cardiac mitochondria from α1A-KO mice had deficits in fatty acid-dependent respiration, FAO, and ETC enzyme activity. TEM revealed abnormalities of mitochondrial morphology characteristic of these functional deficits. The selective α1A-AR agonist A61603 enhanced fatty-acid dependent respiration, fatty acid oxidation, and ETC enzyme activity in isolated cardiac mitochondria. The β-AR agonist isoproterenol enhanced oxidative stress in vitro and this adverse effect was mitigated by A61603. A61603 enhanced ETC Complex I activity and protected contractile function following myocardial infarction.ConclusionsCollectively, these novel findings position α1A-ARs as critical regulators of cardiomyocyte metabolism in the basal state and suggest that metabolic mechanisms may underlie the protective effects of α1A-AR activation in the failing heart.
| S-EPMC10861168 | biostudies-literature
Project description:Septic shock results from bacterial infection and is associated with multi-organ failure, high mortality, and cardiac dysfunction. Sepsis causes both myocardial inflammation and energy depletion. We hypothesized that reduced cardiac energy production is a primary cause of ventricular dysfunction in sepsis. The JNK pathway is activated in sepsis and has also been implicated in impaired fatty acid oxidation in several tissues. Therefore, we tested whether JNK activation inhibits cardiac fatty acid oxidation and whether blocking JNK would restore fatty acid oxidation during LPS treatment. LPS treatment of C57BL/6 mice and adenovirus-mediated activation of the JNK pathway in cardiomyocytes inhibited peroxisome proliferator-activated receptor α expression and fatty acid oxidation. Surprisingly, none of the adaptive responses that have been described in other types of heart failure, such as increased glucose utilization, reduced αMHC:βMHC ratio or induction of certain microRNAs, occurred in LPS-treated mice. Treatment of C57BL/6 mice with a general JNK inhibitor (SP600125) increased fatty acid oxidation in mice and a cardiomyocyte-derived cell line. JNK inhibition also prevented LPS-mediated reduction in fatty acid oxidation and cardiac dysfunction. Inflammation was not alleviated in LPS-treated mice that received the JNK inhibitor. We conclude that activation of JNK signaling reduces fatty acid oxidation and prevents the peroxisome proliferator-activated receptor α down-regulation that occurs with LPS.
| S-EPMC3196095 | biostudies-literature
Project description:BackgroundTranslation of preclinical findings could benefit from a simple, reproducible, high throughput human model to study myocardial signaling. Alpha-1A-adrenergic receptors (ARs) are expressed at very low levels in the human heart, and it is unknown if they function.ObjectivesTo develop a high throughput human myocardial slice culture model, and to test the hypothesis that alpha-1A- ARs are functional in the human heart.MethodsCores of LV free wall 8 mm diameter were taken from 52 hearts (18 failing and 34 nonfailing). Slices 250 μm thick were cut with a Krumdieck apparatus and cultured using a rotating incubation unit.ResultsAbout 60 slices were cut from each LV core, and a typical study could use 96 slices. Myocyte morphology was maintained, and diffusion into the slice center was rapid. Slice viability was stable for at least 3 days in culture by ATP and MTT assays. The beta-AR agonist isoproterenol stimulated phospholamban phosphorylation, and the alpha-1A-AR agonist A61603 stimulated ERK phosphorylation, with nanomolar EC50 values in slices from both failing and nonfailing hearts. Strips cut from the slices were used to quantify activation of contraction by isoproterenol, A61603, and phenylephrine. The slices supported transduction by adenovirus.ConclusionsWe have developed a simple, high throughput LV myocardial slice culture model to study signaling in the human heart. This model can be useful for translational studies, and we show for the first time that the alpha-1A-AR is functional in signaling and contraction in the human heart.
| S-EPMC4955869 | biostudies-literature
Project description:Liver X receptor (LXR)α is a nuclear receptor that responds to oxysterols and cholesterol overload by stimulating cholesterol efflux, transport, conversion to bile acids, and excretion. LXRα binds to and is regulated by synthetic (T-0901317, GW3695) and endogenous (oxysterols) ligands. LXRα activity is also modulated by FAs, but the ligand binding specificity of FA and acyl-CoA derivatives for LXRα remains unknown. We investigated whether LXRα binds FA or FA acyl-CoA with affinities that mimic in vivo concentrations, examined the effect of FA chain length and the degree of unsaturation on binding, and investigated whether FAs regulate LXRα activation. Saturated medium-chain FA (MCFA) displayed binding affinities in the low nanomolar concentration range, while long-chain fatty acyl-CoA did not bind or bound weakly to LXRα. Circular dichroic spectra and computational docking experiments confirmed that MCFA bound to the LXRα ligand binding pocket similar to the known synthetic agonist of LXRα (T0901317), but with limited change to the conformation of the receptor. Transactivation assays showed that MCFA activated LXRα, whereas long-chain FA caused no effect. Our results suggest that LXRα functions as a receptor for saturated FA or acyl-CoA of C10 and C12 in length.
| S-EPMC5282955 | biostudies-literature
Project description:Fatty acids are the most major substrate source for adult cardiac energy generation. Prohibitin 2 (PHB2), a highly conserved protein located in mitochondrial inner membrane, plays key roles in cellular energy metabolic homeostasis. However, its functions in regulating cardiac fatty acid metabolism have remained largely unknown. Our study demonstrates that cardiac-specific knockout of Phb2 leads to accumulation of lipid droplets and causes heart failure. Mechanistically, ablation of PHB2 impairs cardiac fatty acid oxidation (FAO) through downregulating carnitine palmitoyltransferase1b (CPT1b), a rate-limiting enzyme of cardiac mitochondrial FAO. Moreover, overexpression of CPT1b alleviates impaired FAO in PHB2-deficient cardiomyocytes. Thus, our study provides direct evidence for the link between PHB2 and cardiac fatty acid metabolism. Our study points out that PHB2 is a potential FAO regulator in cardiac mitochondrial inner membrane, as well as the connection between PHB2 and CPT1b and their relationships to cardiac pathology especially to cardiac fatty acid metabolic disorder.
| S-EPMC7067801 | biostudies-literature
Project description:Ischemic brain injury impacts cardiac dysfunction depending on the part of the brain affected, with a manifestation of irregular blood pressure, arrhythmia, and heart failure. Generally called brain-heart syndrome in traditional Chinese medicine, few mechanistic understanding and treatment options are available at present. We hypothesize that considering the established efficacy for both ischemic stroke and myocardial infarction (MI), Danhong injection (DHI), a multicomponent Chinese patent medicine, may have a dual pharmacological potential for treating the brain-heart syndrome caused by cerebral ischemic stroke through its multi-targeted mechanisms. We investigated the role of DHI in the setting of brain-heart syndrome and determined the mechanism by which it regulates this process. We induced Ischemia/Reperfusion in Wistar rats and administered intravenous dose of DHI twice daily for 14 days. We assessed the neurological state, infarct volume, CT scan, arterial blood pressure, heart rhythm, and the hemodynamics. We harvested the brain and heart tissues for immunohistochemistry and western blot analyses. Our data show that DHI exerts potent anti-stroke effects (infarct volume reduction: ∗∗p < 0.01 and ∗∗∗p < 0.001 vs. vehicle. Neurological deficit correction: ∗p < 0.05 and ∗∗∗p < 0.001 vs. vehicle), and effectively reversed the abnormal arterial pressure (∗p < 0.05 vs. vehicle) and heart rhythm (∗∗p < 0.01 vs. vehicle). The phenotype of this brain-heart syndrome is strikingly similar to those of MI model. Quantitative assessment of hemodynamic in cardiac functionality revealed a positive uniformity in the PV-loop after administration with DHI and valsartan in the latter. Immunohistochemistry and western blot results showed the inhibitory effect of DHI on the β-adrenergic pathway as well as protein kinase C epsilon (PKCε) (∗∗p < 0.01 vs. model). Our data showed the underlying mechanisms of the brain-heart interaction and offer the first evidence that DHI targets the adrenergic pathway to modulate cardiac function in the setting of brain-heart syndrome. This study has made a novel discovery for proper application of the multi-target DHI and could serve as a therapeutic option in the setting of brain-heart syndrome.
| S-EPMC6037833 | biostudies-literature