scholarly journals Nuclear receptor subfamily 4 group A member 2 inhibits activation of ERK signaling and cell growth in response to β-adrenergic stimulation in adult rat cardiomyocytes

2019 ◽  
Vol 317 (3) ◽  
pp. C513-C524 ◽  
Author(s):  
Sadia Ashraf ◽  
Yassmin K. Hegazy ◽  
Romain Harmancey
Keyword(s):  
Cell Growth ◽  
Nuclear Receptor ◽  
Early Response ◽  
Left Ventricular ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Orphan Nuclear Receptor ◽  
Adrenergic Stimulation ◽  
Rat Cardiomyocytes ◽  
Adult Rat

Sustained elevation of sympathetic activity is an important contributor to pathological cardiac hypertrophy, ventricular arrhythmias, and left ventricular contractile dysfunction in chronic heart failure. The orphan nuclear receptor NR4A2 is an immediate early-response gene activated in the heart under β-adrenergic stimulation. The goal of this study was to identify the transcriptional remodeling events induced by increased NR4A2 expression in cardiomyocytes and their impact on the physiological response of those cells to sustained β-adrenergic stimulation. Treatment of adult rat ventricular myocytes with isoproterenol induced a rapid (<4 h) increase in NR4A2 levels that was accompanied by a transient (<24 h) increase in nuclear localization of the transcription factor. Adenovirus-mediated overexpression of NR4A2 to similar levels modulated the expression of genes linked to adrenoceptor signaling, calcium signaling, cell growth and proliferation and counteracted the increase in protein synthesis rate and cell surface area mediated by chronic isoproterenol stimulation. Consistent with those findings, NR4A2 overexpression also blocked the phosphorylative activation of growth-related kinases ERK1/2, Akt, and p70 S6 kinase. Prominent among the transcriptional changes induced by NR4A2 was the upregulation of the dual-specificity phosphatases DUSP2 and DUSP14, two known inhibitors of ERK1/2. Pretreatment of NR4A2-overexpressing cardiomyocytes with the DUSP inhibitor BCI [( E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1 H-inden-1-one] prevented the inhibition of ERK1/2 following isoproterenol stimulation. In conclusion, our results suggest that NR4A2 acts as a novel negative feedback regulator of the β-adrenergic receptor-mediated growth response in cardiomyocytes and this at least partly through DUSP-mediated inhibition of ERK1/2 signaling.

scholarly journals Metabolic Interventions to Prevent Hypertrophy-Induced Alterations in Contractile Properties In Vitro

2021 ◽  
Vol 22 (7) ◽  
pp. 3620
Author(s):  
Ilvy M. E. Geraets ◽  
Will A. Coumans ◽  
Agnieszka Strzelecka ◽  
Patrick Schönleitner ◽  
Gudrun Antoons ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Glucose Uptake ◽  
Contractile Function ◽  
Contractile Properties ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Adrenergic Stimulation ◽  
Rat Cardiomyocytes ◽  
Functional Changes

(1) Background: The exact mechanism(s) underlying pathological changes in a heart in transition to hypertrophy and failure are not yet fully understood. However, alterations in cardiac energy metabolism seem to be an important contributor. We characterized an in vitro model of adrenergic stimulation-induced cardiac hypertrophy for studying metabolic, structural, and functional changes over time. Accordingly, we investigated whether metabolic interventions prevent cardiac structural and functional changes; (2) Methods: Primary rat cardiomyocytes were treated with phenylephrine (PE) for 16 h, 24 h, or 48 h, whereafter hypertrophic marker expression, protein synthesis rate, glucose uptake, and contractile function were assessed; (3) Results: 24 h PE treatment increased expression of hypertrophic markers, phosphorylation of hypertrophy-related signaling kinases, protein synthesis, and glucose uptake. Importantly, the increased glucose uptake preceded structural and functional changes, suggesting a causal role for metabolism in the onset of PE-induced hypertrophy. Indeed, PE treatment in the presence of a PAN-Akt inhibitor or of a GLUT4 inhibitor dipyridamole prevented PE-induced increases in cellular glucose uptake and ameliorated PE-induced contractile alterations; (4) Conclusions: Pharmacological interventions, forcing substrate metabolism away from glucose utilization, improved contractile properties in PE-treated cardiomyocytes, suggesting that targeting glucose uptake, independent from protein synthesis, forms a promising strategy to prevent hypertrophy and hypertrophy-induced cardiac dysfunction.

scholarly journals The Orphan Nuclear Receptor 4A1: A Potential New Therapeutic Target for Metabolic Diseases

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Lei Zhang ◽  
Qun Wang ◽  
Wen Liu ◽  
Fangyan Liu ◽  
Ailing Ji ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Lipid Metabolism ◽  
Nuclear Receptor ◽  
Metabolic Diseases ◽  
Early Response ◽  
Orphan Receptor ◽  
Special Focus ◽  
Orphan Nuclear Receptor ◽  
Physiological Functions ◽  
The Impact

Orphan nuclear receptor 4A1 (NR4A1) is a transcriptional factor of the nuclear orphan receptor (NR4A) superfamily that has sparked interest across different research fields in recent years. Several studies have demonstrated that ligand-independent NR4A1 is an immediate-early response gene and the protein product is rapidly induced by a variety of stimuli. Hyperfunction or dysfunction of NR4A1 is implicated in various metabolic processes, including carbohydrate metabolism, lipid metabolism, and energy balance, in major metabolic tissues, such as liver, skeletal muscle, pancreatic tissues, and adipose tissues. No endogenous ligands for NR4A1 have been identified, but numerous compounds that bind and activate or inactivate nuclear NR4A1 or induce cytoplasmic localization of NR4A1 have been identified. This review summarizes recent advances in our understanding of the molecular biology and physiological functions of NR4A1. And we focus on the physiological functions of NR4A1 receptor to the development of the metabolic diseases, with a special focus on the impact on carbohydrate and lipid metabolism in skeletal muscle, liver, adipose tissue, and islet.

The orphan nuclear receptor NGFI-B regulates expression of the gene encoding steroid 21-hydroxylase

1993 ◽  
Vol 13 (2) ◽  
pp. 861-868
Author(s):  
T E Wilson ◽  
A R Mouw ◽  
C A Weaver ◽  
J Milbrandt ◽  
K L Parker
Keyword(s):  
Nuclear Receptor ◽  
Transcriptional Activation ◽  
Core Promoter ◽  
Orphan Nuclear Receptor ◽  
Recognition Sequence ◽  
Mobility Shift ◽  
Adrenocortical Cells ◽  
Gene Encoding ◽  
Adult Rat ◽  
Gel Mobility Shift

As part of its trophic action to maintain the steroidogenic capacity of adrenocortical cells, corticotropin (ACTH) increases the transcription of the cytochrome P-450 steroid hydroxylase genes, including the gene encoding steroid 21-hydroxylase (21-OHase). We previously identified several promoter elements that regulate 21-OHase gene expression in mouse Y1 adrenocortical tumor cells. One of these elements, located at nucleotide -65, closely resembles the recognition sequence of the orphan nuclear receptor NGFI-B, suggesting that NGFI-B regulates this essential steroidogenic enzyme. To explore this possibility, we first used in situ hybridization to demonstrate high levels of NGFI-B transcripts in the adrenal cortex of the adult rat. In cultured mouse Y1 adrenocortical cells, treatment with ACTH, the major regulator of 21-OHase transcription, rapidly increased NGFI-B expression. Gel mobility shift and DNase I footprinting experiments showed that recombinantly expressed NGFI-B interacts specifically with the 21-OHase -65 element and identified one complex formed by Y1 extracts and the 21-OHase -65 element that contains NGFI-B. Expression of NGFI-B significantly augmented the activity of the intact 21-OHase promoter, while mutations of the -65 element that abolish NGFI-B binding markedly diminished NGFI-B-mediated transcriptional activation. Specific mutations of NGFI-B shown previously to impair either DNA binding or transcriptional activation diminished the effect of NGFI-B coexpression on 21-OHase expression. Finally, an oligonucleotide containing the NGFI-B response element conferred ACTH response to a core promoter from the prolactin gene, showing that this element is sufficient for ACTH induction. Collectively, these results identify a cellular promoter element that is regulated by NGFI-B and implicate NGFI-B in the transcriptional induction of 21-OHase by ACTH.

Effects of oxygen tension on energetics of cultured vascular smooth muscle

2002 ◽  
Vol 283 (1) ◽  
pp. H110-H117 ◽  
Author(s):  
Anders Lindqvist ◽  
Karl Dreja ◽  
Karl Swärd ◽  
Per Hellstrand
Keyword(s):  
Chronic Hypoxia ◽  
Lactate Production ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Adrenergic Stimulation ◽  
Cellular Mechanisms ◽  
Mitochondrial Uncoupling ◽  
Vascular Abnormalities ◽  
Intracellular Ca ◽  
Glycogen Stores

Chronic hypoxia is a clinically important condition known to cause vascular abnormalities. To investigate the cellular mechanisms involved, we kept rings of a rat tail artery for 4 days in hypoxic culture (HC) or normoxic culture (NC) (Po 2 = 14 vs. 110 mmHg) and then measured contractility, oxygen consumption ( J o2 ), and lactate production ( J lac) in oxygenated medium. Compared with fresh rings, basal ATP turnover ( J ATP) was decreased in HC, but not in NC, with a shift from oxidative toward glycolytic metabolism. J o2 during mitochondrial uncoupling was reduced by HC but not by NC. Glycogen stores were increased 40-fold by HC and fourfold by NC. Maximum tension in response to norepinephrine and the Jo2 versus tension relationship ( J o2 vs. high K+ elicited force) were unaffected by either HC or NC. Force transients in response to caffeine were increased in HC, whereas intracellular Ca2+ wave activity during adrenergic stimulation was decreased. Protein synthesis rate was reduced by HC. The results show that long-term hypoxia depresses basal energy turnover, impairs mitochondrial capacity, and alters Ca2+homeostasis, but does not affect contractile energetics. These alterations may form a basis for vascular damage by chronic hypoxia.

scholarly journals Interaction of Metabolic and Respiratory Acidosis with α and β-adrenoceptor Stimulation in Rat Myocardium

2012 ◽  
Vol 117 (6) ◽  
pp. 1212-1222 ◽  
Author(s):  
Matthieu Biais ◽  
Romain Jouffroy ◽  
Aude Carillion ◽  
Sarah Feldman ◽  
Aude Jobart-Malfait ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Intracellular Ph ◽  
Respiratory Acidosis ◽  
Adenosine Monophosphate ◽  
Left Ventricular ◽  
Rat Myocardium ◽  
Adrenergic Stimulation ◽  
Rat Cardiomyocytes ◽  
Inotropic Effects ◽  
Isolated Rat

Background The effects of acute respiratory versus metabolic acidosis on the myocardium and their consequences on adrenoceptor stimulation remain poorly described. We compared the effects of metabolic and respiratory acidosis on inotropy and lusitropy in rat myocardium and their effects on the responses to α- and β-adrenoceptor stimulations. Methods The effects of acute respiratory and metabolic acidosis (pH 7.10) and their interactions with α and β-adrenoceptor stimulations were studied in isolated rat left ventricular papillary muscle (n=8 per group). Intracellular pH was measured using confocal microscopy and a pH-sensitive fluorophore in isolated rat cardiomyocytes. Data are mean percentages of baseline±SD. Results Respiratory acidosis induced more pronounced negative inotropic effects than metabolic acidosis did both in isotonic (45±3 versus 63±6%, P&lt;0.001) and isometric (44±5 versus 64±3%, P&lt;0.001) conditions concomitant with a greater decrease in intracellular pH (6.85±0.07 versus 7.12±0.07, P&lt;0.001). The response to α-adrenergic stimulation was not modified by respiratory or metabolic acidosis. The inotropic response to β-adrenergic stimulation was impaired only in metabolic acidosis (137±12 versus 200±33%, P&lt;0.001), but this effect was not observed with administration of forskolin or dibutiryl-cyclic adenosine monophosphate. This effect might be explained by a change in transmembrane pH gradient only observed with metabolic acidosis. The lusitropic response to β-adrenergic stimulation was not modified by respiratory or metabolic acidosis. Conclusion Acute metabolic and respiratory acidosis induce different myocardial effects related to different decreases in intracellular pH. Only metabolic acidosis impairs the positive inotropic effect of β-adrenergic stimulation.

scholarly journals Silica nanoparticles induce cardiotoxicity interfering with energetic status and Ca2+ handling in adult rat cardiomyocytes

2017 ◽  
Vol 312 (4) ◽  
pp. H645-H661 ◽  
Author(s):  
Carlos Enrique Guerrero-Beltrán ◽  
Judith Bernal-Ramírez ◽  
Omar Lozano ◽  
Yuriana Oropeza-Almazán ◽  
Elena Cristina Castillo ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Glutathione Depletion ◽  
Energy Status ◽  
Adrenergic Stimulation ◽  
Rat Cardiomyocytes ◽  
Atp Production ◽  
Adult Rat ◽  
Intracellular Ca ◽  
Rat Myocytes ◽  
Potential Risks

Recent evidence has shown that nanoparticles that have been used to improve or create new functional properties for common products may pose potential risks to human health. Silicon dioxide (SiO2) has emerged as a promising therapy vector for the heart. However, its potential toxicity and mechanisms of damage remain poorly understood. This study provides the first exploration of SiO2-induced toxicity in cultured cardiomyocytes exposed to 7- or 670-nm SiO2 particles. We evaluated the mechanism of cell death in isolated adult cardiomyocytes exposed to 24-h incubation. The SiO2 cell membrane association and internalization were analyzed. SiO2 showed a dose-dependent cytotoxic effect with a half-maximal inhibitory concentration for the 7 nm (99.5 ± 12.4 µg/ml) and 670 nm (>1,500 µg/ml) particles, which indicates size-dependent toxicity. We evaluated cardiomyocyte shortening and intracellular Ca2+ handling, which showed impaired contractility and intracellular Ca2+ transient amplitude during β-adrenergic stimulation in SiO2 treatment. The time to 50% Ca2+ decay increased 39%, and the Ca2+ spark frequency and amplitude decreased by 35 and 21%, respectively, which suggest a reduction in sarcoplasmic reticulum Ca2+-ATPase (SERCA) activity. Moreover, SiO2 treatment depolarized the mitochondrial membrane potential and decreased ATP production by 55%. Notable glutathione depletion and H2O2 generation were also observed. These data indicate that SiO2 increases oxidative stress, which leads to mitochondrial dysfunction and low energy status; these underlie reduced SERCA activity, shortened Ca2+ release, and reduced cell shortening. This mechanism of SiO2 cardiotoxicity potentially plays an important role in the pathophysiology mechanism of heart failure, arrhythmias, and sudden death. NEW & NOTEWORTHY Silica particles are used as novel nanotechnology-based vehicles for diagnostics and therapeutics for the heart. However, their potential hazardous effects remain unknown. Here, the cardiotoxicity of silica nanoparticles in rat myocytes has been described for the first time, showing an impairment of mitochondrial function that interfered directly with Ca2+ handling.

scholarly journals Differential effects of octanoate and heptanoate on myocardial metabolism during extracorporeal membrane oxygenation in an infant swine model

2015 ◽  
Vol 309 (7) ◽  
pp. H1157-H1165 ◽  
Author(s):  
Masaki Kajimoto ◽  
Dolena R. Ledee ◽  
Aaron K. Olson ◽  
Nancy G. Isern ◽  
Christine Des Rosiers ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Extracorporeal Membrane Oxygenation ◽  
Energy State ◽  
Left Ventricular ◽  
Gas Chromatography Mass Spectrometry ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Swine Model ◽  
Acetyl Coa ◽  
Membrane Oxygenation

Nutritional energy support during extracorporeal membrane oxygenation (ECMO) should promote successful myocardial adaptation and eventual weaning from the ECMO circuit. Fatty acids (FAs) are a major myocardial energy source, and medium-chain FAs (MCFAs) are easily taken up by cell and mitochondria without membrane transporters. Odd-numbered MCFAs supply carbons to the citric acid cycle (CAC) via anaplerotic propionyl-CoA as well as acetyl-CoA, the predominant β-oxidation product for even-numbered MCFA. Theoretically, this anaplerotic pathway enhances carbon entry into the CAC, and provides superior energy state and preservation of protein synthesis. We tested this hypothesis in an immature swine model undergoing ECMO. Fifteen male Yorkshire pigs (26–45 days old) with 8-h ECMO received either normal saline, heptanoate (odd-numbered MCFA), or octanoate (even-numbered MCFA) at 2.3 μmol·kg body wt−1·min−1 as MCFAs systemically during ECMO ( n = 5/group). The 13-carbon (13C)-labeled substrates ([2-13C]lactate, [5,6,7-13C3]heptanoate, and [U-13C6]leucine) were systemically infused as metabolic markers for the final 60 min before left ventricular tissue extraction. Extracted tissues were analyzed for the 13C-labeled and absolute concentrations of metabolites by nuclear magnetic resonance and gas chromatography-mass spectrometry. Octanoate produced markedly higher myocardial citrate concentration, and led to a higher [ATP]-to-[ADP] ratio compared with other groups. Unexpectedly, octanoate and heptanoate increased the flux of propionyl-CoA relative to acetyl-CoA into the CAC compared with control. MCFAs promoted increases in leucine oxidation, but were not associated with a difference in protein synthesis rate. In conclusion, octanoate provides energetic advantages to the heart over heptanoate.

scholarly journals Orphan Nuclear Receptor Nur77 Inhibits Cardiac Hypertrophic Response to Beta-Adrenergic Stimulation

2015 ◽  
Vol 35 (19) ◽  
pp. 3312-3323 ◽  
Author(s):  
Guijun Yan ◽  
Ni Zhu ◽  
Shengdong Huang ◽  
Bing Yi ◽  
Xiying Shang ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Nuclear Receptor ◽  
Nuclear Translocation ◽  
Negative Regulator ◽  
Immunofluorescent Staining ◽  
Dependent Manner ◽  
Orphan Nuclear Receptor ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Intramyocardial Injection

The orphan nuclear receptor Nur77 plays critical roles in cardiovascular diseases, and its expression is markedly induced in the heart after beta-adrenergic receptor (β-AR) activation. However, the functional significance of Nur77 in β-AR signaling in the heart remains unclear. By using Northern blot, Western blot, and immunofluorescent staining assays, we showed that Nur77 expression was markedly upregulated in cardiomyocytes in response to multiple hypertrophic stimuli, including isoproterenol (ISO), phenylephrine (PE), and endothelin-1 (ET-1). In a time- and dose-dependent manner, ISO increases Nur77 expression in the nuclei of cardiomyocytes. Overexpression of Nur77 markedly inhibited ISO-induced cardiac hypertrophy by inducing nuclear translocation of Nur77 in cardiomyocytes. Furthermore, cardiac overexpression of Nur77 by intramyocardial injection of Ad-Nur77 substantially inhibited cardiac hypertrophy and ameliorated cardiac dysfunction after chronic infusion of ISO in mice. Mechanistically, we demonstrated that Nur77 functionally interacts with NFATc3 and GATA4 and inhibits their transcriptional activities, which are critical for the development of cardiac hypertrophy. These results demonstrate for the first time that Nur77 is a novel negative regulator for the β-AR-induced cardiac hypertrophy through inhibiting the NFATc3 and GATA4 transcriptional pathways. Targeting Nur77 may represent a potentially novel therapeutic strategy for preventing cardiac hypertrophy and heart failure.

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