Abstract 268: Differential Activation and Subcellular Targeting of Erk1/2 and Akt in Response to β-Adrenergic Receptor-Mediated Transactivation of Epidermal Growth Factor Receptor in Cardiomyocytes

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Laurel A Grisanti ◽  
Jennifer A Talarico ◽  
Rhonda C Carter ◽  
Scott W Radcliffe ◽  
Douglas G Tilley
Keyword(s):  
Heart Failure ◽  
Plasma Membrane ◽  
Cardiac Function ◽  
Growth Factor Receptor ◽  
Subcellular Targeting ◽  
Egfr Transactivation ◽  
Differential Activation ◽  
Akt Phosphorylation ◽  
Egfr Inhibition ◽  
Pi3k Activity

β-adrenergic receptors (βAR) are critical regulators of cardiac function whose dysregulation during heart failure are associated with diminished cardiac function, however βAR-mediated EGFR transactivation has been shown to relay cardioprotection via unknown mechanisms. We hypothesized that EGFR transactivation may result in differential activation and subcellular targeting of prosurvival kinases known to be downstream of EGFR, namely ERK1/2 and Akt. Thus, ERK1/2 and Akt phosphorylation and subcellular distribution was assessed in rat neonatal cardiomyocytes (RNCM). Treatment of RNCM with the βAR agonist isoproterenol (Iso) resulted in significant phosphorylation of both ERK1/2 (P-ERK) and Akt (P-Akt), in the cytosolic, plasma membrane and nuclear fractions. EGFR inhibition with AG1478 resulted in complete ablation of Iso-induced P-ERK in all fractions, as did MEK1/2 inhibition with PD184352. Total ERK levels did not change in any fraction under any condition, which along with the PD184352 data suggests Iso-mediated EGFR-dependent effects on ERK1/2 activity at different cellular locations is reliant upon MEK1/2 trafficking. While Akt phosphorylation in response to Iso-mediated EGFR transactivation was not sensitive to EGFR inhibition in the cytosol, the P-Akt response was completely abrogated by AG1478 in the plasma membrane and nuclear fractions. The PI3K inhibitor LY-294002 blocked Iso-induced Akt phosphorylation in all fractions, confirming reliance upon PI3K activity for Iso-mediated Akt activation. Additionally, total Akt levels remained constant over all treatments except at the plasma membrane, where AG 1478 reduced T-Akt, suggesting that Akt recruitment and PI3K activity each contribute to an increase in plasma membrane-associated P-Akt, whereas increased nuclear P-Akt in response to Iso-induced EGFR signaling depends solely on PI3K activity. In all, these results demonstrate differential impact of βAR-mediated EGFR transactivation on the subcellular activation and targeting of cardiomyocyte ERK1/2 and Akt. Further understanding of the downstream consequences of these effects in response to βAR-mediated EGFR transactivation could lead to improved therapies for the treatment of heart failure.

Abstract 031: β-Adrenergic Receptor-Mediated Transactivation Of Epidermal Growth Factor Receptor Decreases Cardiomyocyte Apoptosis Through Differential Activation Of ERK1/2 and Akt

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Laurel A Grisanti ◽  
Rhonda L Carter ◽  
Justine E Yu ◽  
Ashley R Repas ◽  
Douglas G Tilley
Keyword(s):  
Heart Failure ◽  
Plasma Membrane ◽  
Growth Factor Receptor ◽  
Egfr Transactivation ◽  
Akt Phosphorylation ◽  
Egfr Inhibition ◽  
Neonatal Cardiomyocytes ◽  
Epidermal Growth ◽  
Cardioprotective Effects ◽  
Β Adrenergic Receptors

β-adrenergic receptors (βAR) are critical regulators of cardiac function whose dysregulation during heart failure are associated with diminished function. However, βAR-mediated EGFR transactivation has been shown to relay cardioprotection in a mouse model of heart failure via unknown mechanisms. We hypothesized that transactivation of EGFR promotes survival via distinct cardiomyocyte signaling responses leading to decreases in apoptosis. To test this hypothesis, C57BL/6 mice were injected with isoproterenol (Iso) in the presence or absence of the EGFR antagonist AG1478 and ERK1/2 and Akt phosphorylation and subcellular distribution were assessed. Following 10 min Iso stimulation, increases in ERK1/2 and Akt phosphorylation were observed in cytosolic, plasma membrane and nuclear fractions. Phosphorylation of ERK1/2 were AG1478 sensitive in all three fractions while Akt phosphorylation occurred through EGFR-transactivation only in plasma membrane and nuclear fractions, which was confirmed in rat neonatal cardiomyocytes (RNCM). Additionally, EGFR-transactivation by βAR decreased apoptosis, as measured via caspase 3 activation/activity and TUNEL assay, which was sensitive to inhibition of both ERK1/2 and Akt signaling pathways. Increased phosphorylation of ERK1/2 and Akt in the nucleus and the ability to inhibit Iso-mediated changes in apoptosis with the transcriptional inhibitor Actinomycin D suggested that the cardioprotective effects of Iso-mediated EGFR transactivation may be influenced by changes in gene transcription. An Apoptotsis RT2 PCR Array was used to identify changes in transcript levels of 84 apoptotic genes. Of these, 12 were found to be altered in response to EGFR inhibition in the presence of Iso. These results demonstrate that βAR-mediated EGFR transactivation in the heart induces differential subcellular activation of ERK1/2 and Akt and leads to the promotion of cell survival, in part through the modulation of apoptotic gene expression in cardiomyocytes. Further understanding the downstream consequences of these effects in response to βAR-mediated EGFR transactivation could lead to improved therapies for the treatment of heart failure.

H2O2-induced transactivation of EGF receptor requires Src and mediates ERK1/2, but not Akt, activation in renal cells

2004 ◽  
Vol 286 (5) ◽  
pp. F858-F865 ◽  
Author(s):  
Shougang Zhougang ◽  
Rick G. Schnellmann
Keyword(s):  
Oxidative Stress ◽  
Egf Receptor ◽  
Primary Cultures ◽  
Growth Factor Receptor ◽  
Cell Types ◽  
Dependent Manner ◽  
Egfr Transactivation ◽  
Akt Phosphorylation ◽  
Akt Activation ◽  
Renal Proximal Tubular Cells

Although oxidative stress activates epidermal growth factor receptor (EGFR), ERK1/2, and Akt in a number of cell types, the mechanisms by which oxidative stress activates these kinases are not well defined in renal epithelial cells. Exposure of primary cultures of rabbit renal proximal tubular cells to hydrogen peroxide (H2O2) stimulated Src, EGFR, ERK1/2, and Akt activation in a time-dependent manner as determined by the phosphorylation of each protein. The Src inhibitor PP1 completely blocked EGFR, ERK1/2, and Akt phosphorylation following H2O2 exposure. In contrast, blockade of the EGFR by AG1478 inhibited phosphorylation of ERK1/2 but not Src or Akt phosphorylation following H2O2 exposure. Exogenous EGF stimulated EGFR, ERK1/2, and Akt activation and the EGFR inhibitor blocked phorphorylation of ERK1/2 and Akt. The presence of PP1, but not AG1478, significantly accelerated H2O2-induced cell death. These results suggest that Src mediates H2O2-induced EGFR transactivation. H2O2- and EGF-induced ERK1/2 activation is mediated by EGFR, whereas Akt is activated by Src independent of EGFR following H2O2 exposure. Src-mediated EGFR transactivation contributes to a survival response following oxidative injury.

scholarly journals Impaired Glycolysis Promotes Alcohol Exposure-Induced Apoptosis in HEI-OC1 Cells via Inhibition of EGFR Signaling

2020 ◽  
Vol 21 (2) ◽  
pp. 476 ◽  
Author(s):  
Hyunsook Kang ◽  
Seong Jun Choi ◽  
Kye Hoon Park ◽  
Chi-Kyou Lee ◽  
Jong-Seok Moon
Keyword(s):  
Hearing Loss ◽  
Growth Factor Receptor ◽  
Alcohol Exposure ◽  
Metabolic Dysfunction ◽  
Egfr Signaling ◽  
Akt Phosphorylation ◽  
Egfr Inhibition ◽  
Glycolytic Activity ◽  
Epidermal Growth ◽  
Induced Apoptosis

Glucose metabolism is an important metabolic pathway in the auditory system. Chronic alcohol exposure can cause metabolic dysfunction in auditory cells during hearing loss. While alcohol exposure has been linked to hearing loss, the mechanism by which impaired glycolysis promotes cytotoxicity and cell death in auditory cells remains unclear. Here, we show that the inhibition of epidermal growth factor receptor (EGFR)-induced glycolysis is a critical mechanism for alcohol exposure-induced apoptosis in HEI-OC1 cells. The cytotoxicity via apoptosis was significantly increased by alcohol exposure in HEI-OC1 cells. The glycolytic activity and the levels of hexokinase 1 (HK1) were significantly suppressed by alcohol exposure in HEI-OC1 cells. Mechanistic studies showed that the levels of EGFR and AKT phosphorylation were reduced by alcohol exposure in HEI-OC1 cells. Notably, HK1 expression and glycolytic activity was suppressed by EGFR inhibition in HEI-OC1 cells. These results suggest that impaired glycolysis promotes alcohol exposure-induced apoptosis in HEI-OC1 cells via the inhibition of EGFR signaling.

scholarly journals Cardiomyocyte damage control in heart failure and the role of the sarcolemma

2019 ◽  
Vol 40 (3-4) ◽  
pp. 319-333 ◽  
Author(s):  
Ashraf Kitmitto ◽  
Florence Baudoin ◽  
Elizabeth J. Cartwright
Keyword(s):  
Heart Failure ◽  
Cell Death ◽  
Plasma Membrane ◽  
Cardiac Function ◽  
Structural Integrity ◽  
Damage Control ◽  
Cardiac Contraction ◽  
Membrane Injury ◽  
Cellular Processes ◽  
Repair Mechanisms

Abstract The cardiomyocyte plasma membrane, termed the sarcolemma, is fundamental for regulating a myriad of cellular processes. For example, the structural integrity of the cardiomyocyte sarcolemma is essential for mediating cardiac contraction by forming microdomains such as the t-tubular network, caveolae and the intercalated disc. Significantly, remodelling of these sarcolemma microdomains is a key feature in the development and progression of heart failure (HF). However, despite extensive characterisation of the associated molecular and ultrastructural events there is a lack of clarity surrounding the mechanisms driving adverse morphological rearrangements. The sarcolemma also provides protection, and is the cell’s first line of defence, against external stresses such as oxygen and nutrient deprivation, inflammation and oxidative stress with a loss of sarcolemma viability shown to be a key step in cell death via necrosis. Significantly, cumulative cell death is also a feature of HF, and is linked to disease progression and loss of cardiac function. Herein, we will review the link between structural and molecular remodelling of the sarcolemma associated with the progression of HF, specifically considering the evidence for: (i) Whether intrinsic, evolutionary conserved, plasma membrane injury-repair mechanisms are in operation in the heart, and (ii) if deficits in key ‘wound-healing’ proteins (annexins, dysferlin, EHD2 and MG53) may play a yet to be fully appreciated role in triggering sarcolemma microdomain remodelling and/or necrosis. Cardiomyocytes are terminally differentiated with very limited regenerative capability and therefore preserving cell viability and cardiac function is crucially important. This review presents a novel perspective on sarcolemma remodelling by considering whether targeting proteins that regulate sarcolemma injury-repair may hold promise for developing new strategies to attenuate HF progression.

Direct Myocardial Implantation of Human Fetal Stem Cells in Heart Failure Patients: Long-term Results

2010 ◽  
Vol 13 (1) ◽  
pp. 31 ◽  
Author(s):  
Federico Benetti ◽  
Ernesto Pe�herrera ◽  
Teodoro Maldonado ◽  
Yan Duarte Vera ◽  
Valvanur Subramanian ◽  
...  
Keyword(s):  
Heart Failure ◽  
Stem Cells ◽  
Cardiac Function ◽  
Nyha Class ◽  
Left Ventricular ◽  
Long Term Results ◽  
Walk Test ◽  
The Mean ◽  
6 Minute Walk Test ◽  
Minute Walk

Background: End-stage heart failure (HF) is refractory to current standard medical therapy, and the number of donor hearts is insufficient to meet the demand for transplantation. Recent studies suggest autologous stem cell therapy may regenerate cardiomyocytes, stimulate neovascularization, and improve cardiac function and clinical status. Although human fetal-derived stem cells (HFDSCs) have been studied for the treatment of a variety of conditions, no clinical studies have been reported to date on their use in treating HF. We sought to determine the efficacy and safety of HFDSC treatment in HF patients.Methods and Results: Direct myocardial transplantation of HFDSCs by open-chest surgical procedure was performed in 10 patients with HF due to nonischemic, nonchagasic dilated cardiomyopathy. Before and after the procedure, and with no changes in their preoperative doses of medications (digoxin, furosemide, spironolactone, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, betablockers), patients were assessed for New York Heart Association (NYHA) class, performance in the exercise tolerance test (ETT), ejection fraction (EF), left ventricular end-diastolic dimension (LVEDD) via transthoracic echocardiography, performance in the 6-minute walk test, and performance in the Minnesota congestive HF test. All 10 patients survived the operation. One patient had a stroke 3 days after the procedure, and although she later recovered, she was unable to perform the follow-up tests. Another male patient experienced pericardial effusion 3 weeks after the procedure. Although it resolved spontaneously, the patient abandoned his control tests and died 5 months after the procedure. An autopsy of the myocardium suggested that new young cells were present in the cardiomyocyte mix. At 40 months, the mean (SD) NYHA class decreased from 3.4 0.5 to 1.33 0.5 (P = .001); the mean EF increased 31%, from 26.6% 4% to 34.8% 7.2% (P = .005); and the mean ETT increased 291.3%, from 4.25 minutes to 16.63 minutes (128.9% increase in metabolic equivalents, from 2.46 to 5.63) (P < .0001); the mean LVEDD decreased 15%, from 6.85 0.6 cm to 5.80 0.58 cm (P < .001); mean performance in the 6-minute walk test increased by 43.2%, from 251 113.1 seconds to 360 0 seconds (P = .01); the mean distance increased 64.4%, from 284.4 144.9 m to 468.2 89.8 m (P = .004); and the mean result in the Minnesota test decreased from 71 27.3 to 6 5.9 (P < .001).Conclusion: Although these initial findings suggest direct myocardial implantation of HFDSCs is feasible and improves cardiac function in HF patients at 40 months, more clinical research is required to confirm these observations.

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