Β-adrenergic Signaling Research Articles

Danhong Injection Reversed Cardiac Abnormality in Brain-Heart Syndrome via Local and Remote β-Adrenergic Receptor Signaling.

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.

Cardiotoxicity of β-mimetic catecholamines during ontogenetic development — possible risks of antenatal therapy

Catecholamines are involved in the regulation of a wide variety of vital functions. The β-adrenergic receptor (β-AR) - adenylyl cyclase system has been identified early in embryogenesis before the heart has received adrenergic innervation. The structure of β-receptors in the immature myocardium is similar to that in adults; there are, however, significant quantitative developmental changes in the inotropic and chronotropic responsiveness. Information on the toxic effect of the β-AR agonists in the immature heart is surprisingly scarce, even though these agents are used in clinical practice both during pregnancy and in early postnatal development. Large doses of β-AR agonists induce malformations of the cardiovascular system; the type of change depends upon the time at which the β-AR agonist was administered during embryogenesis. During postnatal ontogeny, the cardiotoxicity of β-AR agonists increased from birth to adulthood. It seems likely that despite interspecies differences, developmental changes in the cardiac sensitivity to β-AR agonists may exist in all mammals, depending on the degree of maturation of the system involved in β-adrenergic signaling. All the existing data draw attention to the possible harmful consequences of the clinical use of β-AR agonists during early phases of cardiac development. Late effects of the early disturbances of the cardiac muscle cannot be excluded.

Abstract 134: Dysbiosis of gut microbiota in chronic stressed patients with endometriosis

Abstract Although endometriosis is a benign disease, it has malignant characters such as invasion and migration. Besides, there is an endometrial type of ovarian cancer, which means endometriosis is similar to malignant disease at some extent. Existing researches showed that patients with endometriosis often have high level of chronic stress. Furthermore, chronic stress can promote the growth of endometriosis by activating the β-adrenergic signaling pathway. Gut microbiota is reported to be related to the stress level through the gut-brain axis. So we wonder whether gut microbiota is associated with chronic stress level in endometriosis patients, which may provide a new clinical intervention method to improve prognosis. We grouped the endometriosis patients into stress group and control group with GAD-7 and PHQ-9 questionnaires and collected patients' fecal and tissues samples. Gut microbiota compositions were analyzed by the 16SrRNA gene sequencing-based method and we performed Immunohistochemistry (IHC) to detect the activation of inflammatory pathways in endometriosis tissues. We found that in patients with endometriosis, dysbiosis of gut microbiota is associated with patients' stress levels and Paraprevotella, Odoribacter, Veillonell and Ruminococcus show significant differences with reduced levels in chronic stressed endometriosis patients group, which represents a disease-specific change of gut microbiota on the genus level. Besides, compared to the control group, the expression level of inflammatory cytokines, NF-κB p65 and COX-2, increased in the chronic stressed patients group, which means that dysbiosis of gut microbiota may active the inflammatory pathway of gut-brain axis. In conclusion, we found new disease-specific changes of gut microbiota in chronic stressed patients with endometriosis, which can be a new examination target of chronic stress level and may provide an adjuvant therapy method for clinical psychological intervention, reducing the stress level and improving the prognosis of endometriosis patients. Citation Format: Jing Xu, Yu Kang, Yinhua Yu. Dysbiosis of gut microbiota in chronic stressed patients with endometriosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 134.

Prometastatic Molecular Profiles in Breast Tumors From Socially Isolated Women.

BackgroundSocial isolation is associated with accelerated breast cancer progression and increased disease recurrence and mortality, but the underlying biological mechanisms remain poorly understood. In preclinical models, beta-adrenergic signaling from fight-or-flight stress responses can stimulate prometastatic processes in the tumor microenvironment including upregulation of M2 macrophages, epithelial–mesenchymal transition (EMT), and lymphovascular invasion. This study examines whether the same pathways are upregulated in breast tumors from socially isolated cancer patients.MethodsEMT and M1/M2 macrophage gene expression programs were analyzed by genome-wide transcriptional profiling, and lymphatic and vascular density were assessed by immunohistochemistry in primary tumors from 56 early-stage breast cancer patients who were part of the UCLA RISE study. Social isolation was quantified by the Social Provisions Scale, and disease characteristics were assessed by medical record review. General linear models were used to quantify differential gene expression across risk factor groups. Linear regression models were used to examine associations between social isolation and lymphovascular invasion.ResultsTumors from socially isolated patients showed upregulated expression of genes involved in EMT (average score difference = +0.080 log2 mRNA abundance ± 0.034 standard error) and M2 macrophage polarization (+0.033 ± 0.014) as well as increased density of lymphatic vessels (β= –.29) but no difference in blood vessel density. TELiS promoter–based bioinformatics analyses indicated activation of CREB family transcription factors that mediate the gene-regulatory effects of β-adrenergic signaling (log2 fold-difference in promoter binding site prevalence: mean ± standard error = +0.49 ± 0.19). ConclusionsPrimary breast tumors from socially isolated patients show multiple prometastatic molecular alterations, providing a plausible biological pathway through which poor social support may accelerate breast cancer progression and defining new targets for intervention.

Cardiac β-adrenergic responsiveness of obese Zucker rats: The role of AMPK.

What is the central question of the study? Is the reduced signalling of AMP-activated protein kinase (AMPK), a key regulator of energy homeostasis in the heart, responsible for the reduced β-adrenergic responsiveness of the heart in obesity? What is the main finding and its importance? Inhibition of AMPK in isolated hearts prevented the reduced cardiac β-adrenergic responsiveness of obese rats, which was accompanied by reduced phosphorylation of AMPK, a proxy of AMPK activity. This suggests a direct functional link between β-adrenergic responsiveness and AMPK signalling in the heart, and it suggests that AMPK might be an important target to restore the β-adrenergic responsiveness in the heart in obesity. The obesity epidemic impacts heavily on cardiovascular health, in part owing to changes in cardiac metabolism. AMP-activated protein kinase (AMPK) is a key regulator of energy homeostasis in the heart and is regulated by β-adrenoceptors (β-ARs) in normal conditions. In obesity, chronic sympathetic overactivation leads to impaired cardiac β-AR responsiveness, although it is unclear whether AMPK signalling, downstream of β-ARs, contributes to this dysfunction. Therefore, we aimed to determine whether reduced AMPK signalling is responsible for the reduced β-AR responsiveness in obesity. In isolated hearts of lean and obese Zucker rats, we tested β-AR responsiveness to the β1 -AR agonist isoprenaline (ISO, 1×10-10 to 5×10-8 m) in the absence and presence of the AMPK inhibitor, compoundC (CC, 10μm). The β1 -AR expression and AMPK phosphorylation were assessed by Western blot. β-Adrenergic responsiveness was reduced in the hearts of obese rats (logEC50 of ISO-developed pressure dose-response curves: lean -8.53±0.13×10x mversus obese -8.35±0.10×10x m ; P<0.05 lean versus obese, n=6 per group). This difference was not apparent after AMPK inhibition (logEC50 of ISO-developed pressure curves: lean CC -8.19±0.12×10x mversus obese CC 8.17±0.13×10x m, P<0.05, n=6 per group). β1 -Adrenergic receptor expression and AMPK phosphorylation were reduced in hearts of obese rats (AMPK at Thr172 : lean 1.73±0.17a.u.versus lean CC 0.81±0.13a.u., and obese 1.18±0.09a.u.versus obese CC 0.81±0.16a.u., P<0.05, n=6 per group). Thus, a direct functional link between β-adrenergic responsiveness and AMPK signalling in the heart exists, and AMPK might be an important target to restore the reduced cardiac β-adrenergic responsiveness in obesity.

An Hsp20-FBXO4 Axis Regulates Adipocyte Function through Modulating PPARγ Ubiquitination

Exposure to cold temperature is well known to upregulate heat shock protein (Hsp) expression and recruit and/or activate brown adipose tissue and beige adipocytes in humans and animals. However, whether and how Hsps regulate adipocyte function for energy homeostatic responses is poorly understood. Here, we demonstrate a critical role of Hsp20 as a negative regulator of adipocyte function. Deletion of Hsp20 enhances non-shivering thermogenesis and suppresses inflammatory responses, leading to improvement of glucose and lipid metabolism under both chow diet and high-fat diet conditions. Mechanistically, Hsp20 controls adipocyte function by interacting with the subunit of the ubiquitin ligase complex, F-box only protein 4 (FBXO4), and regulating the ubiquitin-dependent degradation of peroxisome proliferation activated receptor gamma (PPARγ). Indeed, Hsp20 deficiency mimics and enhances the pharmacological effects of the PPARγ agonist rosiglitazone. Together, our findings suggest a role of Hsp20 in mediating adipocyte function by linking β-adrenergic signaling to PPARγ activity.

Using iPSC Models to Probe Regulation of Cardiac Ion Channel Function.

Cardiovascular disease is the leading contributor to mortality and morbidity. Many deaths of heart failure patients can be attributed to sudden cardiac death due primarily to ventricular arrhythmia. Currently, most anti-arrhythmics modulate ion channel conductivity or β-adrenergic signaling, but these drugs have limited efficacy for some indications, and can potentially be proarrhythmic. Recent studies have shown that mutations in proteins other than cardiac ion channels may confer susceptibility to congenital as well as acquired arrhythmias. Additionally, ion channels themselves are subject to regulation at the levels of channel expression, trafficking and post-translational modification; thus, research into the regulation of ion channels may elucidate disease mechanisms and potential therapeutic targets for future drug development. This review summarizes the current knowledge of the molecular mechanisms of arrhythmia susceptibility and discusses technological advances such as induced pluripotent stem cell-derived cardiomyocytes, gene editing, functional genomics, and physiological screening platforms that provide a new paradigm for discovery of new therapeutic targets to treat congenital and acquired diseases of the heart rhythm.

β-adrenergic receptors and cardiac progenitor cell biology: What is the real connection?

Resident cardiac progenitor cells (CPCs) isolated from small animal models may not always be representative of their human counterparts, especially when significant differences in isolation protocols are considered. Nonetheless, multiple evidences support an important role of β-adrenergic signaling in human CPC survival and commitment, which will need appropriate consideration for future developments of human CPCs as regenerative medicine tools.

Perioperative inhibition of β-adrenergic and COX2 signaling in a clinical trial in breast cancer patients improves tumor Ki-67 expression, serum cytokine levels, and PBMCs transcriptome

Catecholamines and prostaglandins are secreted abundantly during the perioperative period in response to stress and surgery, and were shown by translational studies to promote tumor metastasis. Here, in a phase-II biomarker clinical trial in breast cancer patients (n = 38), we tested the combined perioperative use of the β-blocker, propranolol, and the COX2-inhibitor, etodolac, scheduled for 11 consecutive perioperative days, starting 5 days before surgery. Blood samples were taken before treatment (T1), on the mornings before and after surgery (T2&T3), and after treatment cessation (T4). Drugs were well tolerated. Results based on a-priori hypotheses indicated that already before surgery (T2), serum levels of pro-inflammatory IL-6, CRP, and IFNγ, and anti-inflammatory, cortisol and IL-10, increased. At T2 and/or T3, drug treatment reduced serum levels of the above pro-inflammatory cytokines and of TRAIL, as well as activity of multiple inflammation-related transcription factors (including NFκB, STAT3, ISRE), but not serum levels of cortisol, IL-10, IL-18, IL-8, VEGF and TNFα. In the excised tumor, treatment reduced the expression of the proliferation marker Ki-67, and positively affected its transcription factors SP1 and AhR. Exploratory analyses of transcriptome modulation in PBMCs revealed treatment-induced improvement at T2/T3 in several transcription factors that in primary tumors indicate poor prognosis (CUX1, THRa, EVI1, RORa, PBX1, and T3R), angiogenesis (YY1), EMT (GATA1 and deltaEF1/ZEB1), proliferation (GATA2), and glucocorticoids response (GRE), while increasing the activity of the oncogenes c-MYB and N-MYC. Overall, the drug treatment may benefit breast cancer patients through reducing systemic inflammation and pro-metastatic/pro-growth biomarkers in the excised tumor and PBMCs.

Neurotransmitter Switching Coupled to β-Adrenergic Signaling in Sympathetic Neurons in Prehypertensive States.

Single or combinatorial administration of β-blockers is a mainstay treatment strategy for conditions caused by sympathetic overactivity. Conventional wisdom suggests that the main beneficial effect of β-blockers includes resensitization and restoration of β1-adrenergic signaling pathways in the myocardium, improvements in cardiomyocyte contractility, and reversal of ventricular sensitization. However, emerging evidence indicates that another beneficial effect of β-blockers in disease may reside in sympathetic neurons. We investigated whether β-adrenoceptors are present on postganglionic sympathetic neurons and facilitate neurotransmission in a feed-forward manner. Using a combination of immunocytochemistry, RNA sequencing, Förster resonance energy transfer, and intracellular Ca2+ imaging, we demonstrate the presence of β-adrenoceptors on presynaptic sympathetic neurons in both human and rat stellate ganglia. In diseased neurons from the prehypertensive rat, there was enhanced β-adrenoceptor-mediated signaling predominantly via β2-adrenoceptor activation. Moreover, in human and rat neurons, we identified the presence of the epinephrine-synthesizing enzyme PNMT (phenylethanolamine-N-methyltransferase). Using high-pressure liquid chromatography with electrochemical detection, we measured greater epinephrine content and evoked release from the prehypertensive rat cardiac-stellate ganglia. We conclude that neurotransmitter switching resulting in enhanced epinephrine release, may provide presynaptic positive feedback on β-adrenoceptors to promote further release, that leads to greater postsynaptic excitability in disease, before increases in arterial blood pressure. Targeting neuronal β-adrenoceptor downstream signaling could provide therapeutic opportunity to minimize end-organ damage caused by sympathetic overactivity.

17β-Estradiol and/or estrogen receptor alpha signaling blocks protein phosphatase 1 mediated ISO induced cardiac hypertrophy.

Earlier studies have shown that estrogen possess protective function against the development of pathological cardiac hypertrophy. However, the molecular mechanisms of estrogens (E2) protective effect are poorly understood. Additionally, abnormal activation of β-adrenergic signaling have been implicated in the development of pathological cardiac remodeling. However, the role of serine/threonine protein phosphatase 1 (PP1) in pathological cardiac remodeling under the influence of β-adrenergic signaling have been sparsely investigated. In this study, we assessed the downstream effects of abnormal activation of PP1 upon isoproterenol (ISO) induced pathological cardiac changes. We found that pre-treatment of 17β-estradiol (E2), tet-on estrogen receptor-α, or both significantly inhibited ISO-induced increase in cell size, hypertrophy marker gene expression and cytosolic calcium accumulation in H9c2 cells. Additionally, treatment with estrogen receptor inhibitor (ICI) reversed those effects, implicating role of E2 in inhibiting pathological cardiac remodeling. However, specific inhibition of ERα using melatonin, reduced ISO-induced PP1c expression and enhanced the level of ser-16 phosphorylated phospholamban (PLB), responsible for regulation of sarcoplasmic reticulum Ca2+-ATPase (SERCA) activity. Furthermore, hypertrophic effect caused by overexpression of PP1cα was reduced by treatment with specific inhibitor of ERα. Collectively, we found that estrogen and estrogen receptor-α have protective effect against pathological cardiac changes by suppressing PP1 expression and its downstream signaling pathway, which further needs to be elucidated.

Expression Of Markers Of Browning In White Adipose Tissue In Life-long Endurance Trained Athletes

Physical exercise and training results in adaptations in adipose tissue. Such adaptations may in part be mediated through “cross-talk” with skeletal muscle. One of these adaptations potentially relevant to energy metabolism in endurance athletes is the beiging of white adipose tissue (WAT). Beiging is the process by which WAT shows characteristics of brown adipose tissue (BAT), possibly increasing basal metabolic rate. While the process of beiging in rodents and the existence of BAT in humans has been shown previously, it is unknown if and how life-long endurance exercise influences beiging of WAT depots. PURPOSE: To study the influence of life-long training on adipose tissue markers of beiging and metabolic performance, the uncoupling protein 1 (UCP-1), CIDEA and PPAR-γ in white adipose tissue (WAT) in sub-elite athletes. METHODS: Periumbilical subcutaneous adipose tissue biopsies were collected from 14 life-long trained sub-elite endurance athletes (8 male, 6 female; VO max performance over 90th percentile for their age group) and 13 age-matched controls (6 male 7 female). Gene expression was analyzed on extracted RNA. Fold induction was statistically analyzed by Student’s-test. RESULTS: UCP-1 gene expression was significantly higher in trained women compared with the control group (p=0.046). No significant difference was found in men when comparing UCP-1 expression (p=0.257). Expression of CIDEA was, again, significantly higher compared with controls (p=0.049), but also in men (p=0.024). Finally, expression of PPAR-γ was significantly higher in trained women (p=0.005). Again no differences were found in men (p=0.924). CONCLUSION: Life-long endurance training results in a higher expression of brown adipose tissue markers in periumbilical WAT in women, in men only in expression of CIDEA, a factory closely associated with metabolic health. Previous results in rodents show a higher susceptibility of females to upregulate BAT markers following β-adrenergic signaling. A similar mechanism might be possible in humans. This effect might also be caused by differences in body fat distribution and functionality, with women having a higher prevalence for BAT.

β-Adrenergic signaling is required for the induction of a labile state during memory reconsolidation

Memory reconsolidation is the process by which previously consolidated memories reenter a labile state through reactivation of the memory trace and are actively consolidated through de novo protein synthesis. Although extensive studies have shown that β-adrenergic signaling plays a critical role in the restabilization of reactivated memory, its role in the destabilization of long-term memory is not well-studied. In this study, we found that membrane excitability increased in hippocampal CA1 neurons immediately after the retrieval of contextual fear memory. Interestingly, this increase in membrane excitability diminished after treatment with propranolol (a β-adrenergic receptor antagonist), an NMDA receptor antagonist, and a PKA inhibitor. In addition, we found that administration of propranolol prior to, but not after, the retrieval of fear memory ameliorated the memory impairment caused by anisomycin, indicating that inhibition of β-adrenergic signaling blocks the destabilization of contextual fear memory. Taken together, these results indicate that β-adrenergic signaling via NMDA receptors and PKA signaling pathway induces a labile state of long-term memory through increased neuronal membrane excitability.

Histone demethylase JMJD1A coordinates acute and chronic adaptation to cold stress via thermogenic phospho-switch

In acute cold stress in mammals, JMJD1A, a histone H3 lysine 9 (H3K9) demethylase, upregulates thermogenic gene expressions through β-adrenergic signaling in brown adipose tissue (BAT). Aside BAT-driven thermogenesis, mammals have another mechanism to cope with long-term cold stress by inducing the browning of the subcutaneous white adipose tissue (scWAT). Here, we show that this occurs through a two-step process that requires both β-adrenergic-dependent phosphorylation of S265 and demethylation of H3K9me2 by JMJD1A. The histone demethylation-independent acute Ucp1 induction in BAT and demethylation-dependent chronic Ucp1 expression in beige scWAT provides complementary molecular mechanisms to ensure an ordered transition between acute and chronic adaptation to cold stress. JMJD1A mediates two major signaling pathways, namely, β-adrenergic receptor and peroxisome proliferator-activated receptor-γ (PPARγ) activation, via PRDM16-PPARγ-P-JMJD1A complex for beige adipogenesis. S265 phosphorylation of JMJD1A, and the following demethylation of H3K9me2 might prove to be a novel molecular target for the treatment of metabolic disorders, via promoting beige adipogenesis.

Cardioprotection by intermittent hypoxia conditioning: evidence, mechanisms, and therapeutic potential.

The calibrated application of limited-duration, cyclic, moderately intense hypoxia-reoxygenation increases cardiac resistance to ischemia-reperfusion stress. These intermittent hypoxic conditioning (IHC) programs consistently produce striking reductions in myocardial infarction and ventricular tachyarrhythmias after coronary artery occlusion and reperfusion and, in many cases, improve contractile function and coronary blood flow. These IHC protocols are fundamentally different from those used to simulate sleep apnea, a recognized cardiovascular risk factor. In clinical studies, IHC improved exercise capacity and decreased arrhythmias in patients with coronary artery or pulmonary disease and produced robust, persistent, antihypertensive effects in patients with essential hypertension. The protection afforded by IHC develops gradually and depends on β-adrenergic, δ-opioidergic, and reactive oxygen-nitrogen signaling pathways that use protein kinases and adaptive transcription factors. In summary, adaptation to intermittent hypoxia offers a practical, largely unrecognized means of protecting myocardium from impending ischemia. The myocardial and perhaps broader systemic protection provided by IHC clearly merits further evaluation as a discrete intervention and as a potential complement to conventional pharmaceutical and surgical interventions.

Understanding the Pathophysiology of Psychological Distress and Pancreatic Cancer: A Systematic Review.

Psychological distress is highly prevalent in patients with pancreatic cancer (PC), yet little is known about the pathophysiology underlying the relationship between these 2 diseases. Our aim was to systematically review the evidence examining the pathophysiological mechanisms of the association between PC and psychological distress. A systematic review of the literature was conducted using MEDLINE, Embase, PsychINFO, and CINAHL databases and reported according to the preferred reporting items for systematic reviews and meta-analyses guidelines. Studies examining the pathophysiological mechanisms between PC and psychological distress were included for analysis. Eight studies were identified that fulfilled inclusion criteria. Four mechanisms were identified accounting for the possible relationship between psychological distress and PC, including (1) stress-induced β-adrenergic signaling, (2) interleukin-6-mediated effects, (3) kynurenine pathway upregulation, and (4) altered cerebral glucose metabolism. The relationship between psychological distress and PC is complex, and our understanding of these mechanisms may have implications for holistic clinical management and oncological outcome. The evidence exploring the pathophysiology of this interaction is sparse, but most well established with regard to the stress-induced β-adrenergic signaling mechanism. Further studies in larger cohorts are required to elucidate the relationship between PC and psychological distress to be able to identify therapeutic targets for both conditions.

Nitrosative stress uncovers potent β2-adrenergic receptor-linked vasodilation further enhanced by blockade of clathrin endosome formation.

This study investigated the effect of sodium nitroprusside (SNP) preexposure on vasodilation via the β-adrenergic receptor (BAR) system. SNP was used as a nitrosative/oxidative proinflammatory insult. Small arterioles were visualized by intravital microscopy in the hamster cheek pouch tissue (isoflurane, n = 45). Control dilation to isoproterenol (EC50: 10-7 mol/l) became biphasic as a function of concentration after 2 min of exposure to SNP (10-4 M), with increased potency at picomolar dilation uncovered and decreased efficacy at the micromolar dilation. Control dilation to curcumin was likewise altered after SNP, but only the increased potency at a low dose was uncovered, whereas micromolar dilation was eliminated. The picomolar dilations were blocked by the potent BAR-2 inverse agonist carazolol (10-9 mol/l). Dynamin inhibition with dynasore mimicked this effect, suggesting that SNP preexposure prevented BAR agonist internalization. Using HeLa cells transfected with BAR-2 tagged with monomeric red fluorescent protein, exposure to 10-8-10-6 mol/l curcumin resulted in internalization and colocalization of BAR-2 and curcumin (FRET) that was prevented by oxidative stress (10-3 mol/l CoCl2), supporting that stress prevented internalization of the BAR agonist with the micromolar agonist. This study presents novel data supporting that distinct pools of BARs are differentially available after inflammatory insult. NEW & NOTEWORTHY Preexposure to an oxidative/nitrosative proinflammatory insult provides a "protective preconditioning" against future oxidative damage. We examined immediate vasoactive and molecular consequences of a brief preexposure via β-adrenergic receptor signaling in small arterioles. Blocked receptor internalization with elevated reactive oxygen levels coincides with a significant and unexpected vasodilation to β-adrenergic agonists at picomolar doses.

Stress-induced protein S-glutathionylation and phosphorylation crosstalk in cardiac sarcomeric proteins - Impact on heart function

BackgroundThe interplay between oxidative stress and other signaling pathways in the contractile machinery regulation during cardiac stress and its consequences on cardiac function remains poorly understood. We evaluated the effect of the crosstalk between β-adrenergic and redox signaling on post-translational modifications of sarcomeric regulatory proteins, Myosin Binding Protein-C (MyBP-C) and Troponin I (TnI). Methods and resultsWe mimicked in vitro high level of physiological cardiac stress by forcing rat hearts to produce high levels of oxidized glutathione. This led to MyBP-C S-glutathionylation associated with lower protein kinase A (PKA) dependent phosphorylations of MyBP-C and TnI, increased myofilament Ca2+ sensitivity, and decreased systolic and diastolic properties of the isolated perfused heart. Moderate physiological cardiac stress achieved in vivo with a single 35 min exercise (Low stress induced by exercise, LSE) increased TnI and cMyBP-C phosphorylations and improved cardiac function in vivo (echocardiography) and ex-vivo (isolated perfused heart). High stress induced by exercise (HSE) altered strongly oxidative stress markers and phosphorylations were unchanged despite increased PKA activity. HSE led to in vivo intrinsic cardiac dysfunction associated with myofilament Ca2+ sensitivity defects. To limit protein S-glutathionylation after HSE, we treated rats with N-acetylcysteine (NAC). NAC restored the ability of PKA to modulate myofilament Ca2+ sensitivity and prevented cardiac dysfunction observed in HSE animals. ConclusionUnder cardiac stress, adrenergic and oxidative signaling pathways work in concert to alter myofilament properties and are key regulators of cardiac function.

Grape pomace extract induced beige cells in white adipose tissue from rats and in 3T3-L1 adipocytes

This study investigated the effects of a grape pomace extract (GPE) rich in phenolic compounds on brown-like adipocyte induction and adiposity in spontaneously hypertensive (SHR) and control normotensive Wistar–Kyoto (WKY) rats fed a high-fat diet (HFD). HFD consumption for 10 weeks significantly increased epididymal white adipose tissue (eWAT) in WKY but not in SHR rats. Supplementation with GPE (300 mg/kg body weight/day) reduced adipocyte diameter and increased levels of proteins that participate in adipogenesis and angiogenesis, i.e., peroxisome-proliferator activated receptor gamma (PPARγ), vascular endothelial grow factor-A (VEGF-A) and its receptor 2 (VEGF-R2), and partially increased the uncoupling protein 1 (UCP-1) in WKY. In both strains, GPE attenuated adipose inflammation. In eWAT from SHR, GPE increased the expression of proteins involved in adipose tissue “browning,” i.e., PPARγ-coactivator-1α (PGC-1α), PPARγ, PR domain containing 16 (PRDM16) and UCP-1. In primary cultures of SHR adipocytes, GPE-induced UCP-1 up-regulation was dependent on p38 and ERK activation. Accordingly, in 3T3-L1 adipocytes treated with palmitate, the addition of GPE (30 μM) activated the β-adrenergic signaling cascade (PKA, AMPK, p38, ERK). This led to the associated up-regulation of proteins involved in mitochondrial biogenesis (PGC-1α, PPARγ, PRDM16 and UCP-1) and fatty acid oxidation (ATGL). These effects were similar to those exerted by (−)-epicatechin and quercetin, major phenolic compounds in GPE. Overall, in HFD-fed rats, supplementation with GPE promoted brown-like cell formation in eWAT and diminished adipose dysfunction. Thus, winemaking residues, rich in bioactive compounds, could be useful to mitigate the adverse effects of HFD-induced adipose dysfunction.

Long-Term Caloric Restriction Improves Cardiac Function, Remodeling, Adrenergic Responsiveness, and Sympathetic Innervation in a Model of Postischemic Heart Failure

Caloric restriction (CR) has been described to have cardioprotective effects and improve functional outcomes in animal models and humans. Chronic ischemic heart failure (HF) is associated with reduced cardiac sympathetic innervation, dysfunctional β-adrenergic receptor signaling, and decreased cardiac inotropic reserve. We tested the effects of a long-term CR diet, started late after myocardial infarction on cardiac function, sympathetic innervation, and β-adrenergic receptor responsiveness in a rat model of postischemic HF. Adult male rats were randomly assigned to myocardial infarction or sham operation and 4 weeks later were further randomized to a 1-year CR or normal diet. One year of CR resulted in a significant reduction in body weight, heart weight, and heart weight/tibia length ratio when compared with normal diet in HF groups. At the end of the study period, echocardiography and histology revealed that HF animals under the CR diet had ameliorated left ventricular remodeling compared with HF rats fed with normal diet. Invasive hemodynamic showed a significant improvement of cardiac inotropic reserve in CR HF rats compared with HF-normal diet animals. Importantly, CR dietary regimen was associated with a significant increase of cardiac sympathetic innervation and with normalized cardiac β-adrenergic receptor levels in HF rats when compared with HF rats on the standard diet. We demonstrate, for the first time, that chronic CR, when started after HF established, can ameliorate cardiac dysfunction and improve inotropic reserve. At the molecular level, we find that chronic CR diet significantly improves sympathetic cardiac innervation and β-adrenergic receptor levels in failing myocardium.