scholarly journals GATA4 is a survival factor in adult cardiac myocytes but is not required for α1A-adrenergic receptor survival signaling

2008 ◽  
Vol 295 (2) ◽  
pp. H699-H707 ◽  
Author(s):  
Yuan Huang ◽  
Casey D. Wright ◽  
Satoru Kobayashi ◽  
Chastity L. Healy ◽  
Megan Elgethun ◽  
...  
Keyword(s):  
Cell Death ◽  
Cardiac Myocytes ◽  
Adrenergic Receptor ◽  
Double Knockout ◽  
Survival Factor ◽  
Downstream Effector ◽  
Adult Cardiac Myocytes ◽  
Survival Signaling ◽  
Downstream Mediator

Recently, we defined an α1A-adrenergic receptor-ERK (α1A-AR-ERK) survival signaling pathway in adult cardiac myocytes. Previous studies in neonatal cardiac myocytes indicated that the cardiac-specific transcription factor GATA4 is a downstream mediator of α1-ERK signaling and that phosphorylation of GATA4 by ERK increases DNA binding and transcriptional activity. Therefore, we examined GATA4 as a potential downstream effector of α1A-ERK survival signaling in adult cardiac myocytes. We measured norepinephrine (NE)-induced cell death in cultured cardiac myocytes lacking α1-ARs (cultured from α1A/B-AR double-knockout mice, α1ABKO mice) that are susceptible to cell death induced by several proapoptotic stimuli, including NE. Our results show that overexpression of GATA4 is sufficient to protect α1ABKO cardiac myocytes from NE-induced cell death. However, we found that the α1A-subtype did not induce phosphorylation or increase the activity of GATA4 in adult mouse cardiac myocytes in culture or in vivo. Furthermore, we examined the effect of siRNA-mediated knockdown of GATA4 on α1A-survival signaling. In α1B-knockout cardiac myocytes, which express only the α1A-subtype and are protected from NE-induced cell death, GATA4 knockdown did not reverse α1A-survival signaling in response to NE. In summary, we found that GATA4 acted as a survival factor by preventing cell death in α1ABKO cardiac myocytes, but GATA4 was not activated by α1-AR stimulation and was not required for α1A-survival signaling in adult cardiac myocytes. This also identifies an important mechanistic difference in α1-signaling between adult and neonatal cardiac myocytes.

Adult cardiac myocytes in primary culture: cell characteristics and insulin-receptor interaction

1985 ◽  
Vol 249 (2) ◽  
pp. H212-H221 ◽  
Author(s):  
J. Eckel ◽  
G. van Echten ◽  
H. Reinauer
Keyword(s):  
Cardiac Myocytes ◽  
Structural Integrity ◽  
Cultured Cells ◽  
Insulin Binding ◽  
Receptor Interaction ◽  
Scatchard Analysis ◽  
Apparent Dissociation Constant ◽  
Adult Cardiac Myocytes ◽  
Receptor Number

Calcium-tolerant adult cardiac myocytes were kept in culture under serum-free conditions in the presence of physiological concentrations of insulin. Up to 4 days, 70% of cells retained their in vivo rodshaped morphology without gross structural alterations. During that period a constant ATP-to-ADP ratio was observed with a mean value of 10.6 +/- 0.5 (n = 4). The rate of [14C]phenylalanine incorporation remained unaltered up to 63 h in culture. Insulin binding to cultured cells was found to be time-and temperature-dependent, reversible, and highly specific. Scatchard analysis of equilibrium binding data showed a curvilinear plot with a high-affinity segment yielding an apparent dissociation constant of 4.5 X 10(-10) mol/l and a receptor number of 125,000 sites/cell. Both affinity and receptor number remained unaltered between 18 and 66 h in culture. [14C]phenylalanine incorporation was stimulated by 108% in cardiocytes cultured in the presence of high concentrations of insulin (1.7 X 10(-7) mol/l) for 63 h, when compared with control cells cultured in the absence of insulin. These data demonstrate the retention of structural integrity, insulin receptors, and insulin responsiveness in primary cultured adult cardiac myocytes and provide a useful model for long-term studies on the regulation of insulin action on the heart.

Abstract 23: Disruption of TRAF2-TAK1-NF-κB Signaling Axis Triggers K-48 Linked Poly-Ubiquitylation of RIP1 and Necrotic Cell Death in Doxorubicin Cardiotoxicity

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Rimpy Dhingra ◽  
Victoria Margulets ◽  
Floribeth Aguilar ◽  
Lorrie A. Kirshenbaum
Keyword(s):  
Cell Death ◽  
Cardiac Myocytes ◽  
Cell Injury ◽  
Ventricular Myocytes ◽  
Necrotic Cell Death ◽  
Ros Production ◽  
Necrotic Cell ◽  
Interacting Protein

The anthracycline doxorubicin (Dox) is a highly effective anti-tumour agent, however, its use is limited by its severe cardiotoxic effects that manifests as heart failure. The decline in cardiac performance induced by doxorubicin remains poorly defined. A critical survival role for the canonical IKKβ -mTOR-NF-κB signaling pathway has been demonstrated in ventricular myocytes. In this report, we demonstrate that, Dox impairs IKKβ-mTOR- NF-κB signaling in ventricular myocytes accompanied by mitochondrial perturbations including mPTP, loss of mitochondrial membrane potential and ROS production. IKKβ- NF-κB signaling involves TRAF 2 mediated ligation of K63- ubiquitin chains to RIP1 (Receptor Interacting Protein 1) which serves as scaffold for recruitment of ubiquitylated Tak1 complexes and phosphorylation-dependent activation of IKKβ -NF-kB signaling. Interestingly, ventricular myocytes treated with dox demonstrated reduction in expression levels of TRAF2 and TAK1, in vivo and in vitro. This was accompanied by a decline in K63- and concomitant increase in K-48 linked polyubiquitination on RIP1, impaired NF-kB activation and necrotic cell death of cardiac myocytes. Interestingly, inhibiting the kinase activity of RIP1 with Necrostatin-1, (Nec1) suppressed necrotic cell injury induced by dox but not NF-kB activation. Concordant with these findings was a marked increase in necrotic cell death in cardiac myocytes defective for IKKB signaling or MEF cells deficient for p65 treated with dox. Notably, mitochondrial perturbations, including PT-pore opening , ROS production, calcium uptake, LDH, Tn(T) and HMGB-1 release and necrotic cell injury induced by dox were completely abrogated by restoring NF-kB signaling in cardiac myocytes or Nec-1. Herein, we provide novel evidence that K-48 linked poly ubiquitylation of RIP1 provides a functional switch that impairs NF-kB activation and signals necrosis in cells treated with dox. Interventions that modulate NF-kB activity may prove beneficial in mitigating the cardiotoxic effects of dox.

scholarly journals Deficient BH4 production via de novo and salvage pathways regulates NO responses to cytokines in adult cardiac myocytes

2008 ◽  
Vol 295 (5) ◽  
pp. H2178-H2187 ◽  
Author(s):  
Irina A. Ionova ◽  
Jeannette Vásquez-Vivar ◽  
Jennifer Whitsett ◽  
Anja Herrnreiter ◽  
Meetha Medhora ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
De Novo ◽  
Regulatory Protein ◽  
Cell Types ◽  
No Production ◽  
Inos Protein ◽  
Protein Dimers ◽  
Adult Cardiac Myocytes ◽  
Salvage Pathways

Adult rat cardiac myocytes typically display a phenotypic response to cytokines manifested by low or no increases in nitric oxide (NO) production via inducible NO synthase (iNOS) that distinguishes them from other cell types. To better characterize this response, we examined the expression of tetrahydrobiopterin (BH4)-synthesizing and arginine-utilizing genes in cytokine-stimulated adult cardiac myocytes. Intracellular BH4 and 7,8-dihydrobiopterin (BH2) and NO production were quantified. Cytokines induced GTP cyclohydrolase and its feedback regulatory protein but with deficient levels of BH4 synthesis. Despite the induction of iNOS protein, cytokine-stimulated adult cardiac myocytes produced little or no increase in NO versus unstimulated cells. Western blot analysis under nonreducing conditions revealed the presence of iNOS monomers. Supplementation with sepiapterin (a precursor of BH4) increased BH4 as well as BH2, but this did not enhance NO levels or eliminate iNOS monomers. Similar findings were confirmed in vivo after treatment of rat cardiac allograft recipients with sepiapterin. It was found that expression of dihydrofolate reductase, required for full activity of the salvage pathway, was not detected in adult cardiac myocytes. Thus, adult cardiac myocytes have a limited capacity to synthesize BH4 after cytokine stimulation. The mechanisms involve posttranslational factors impairing de novo and salvage pathways. These conditions are unable to support active iNOS protein dimers necessary for NO production. These findings raise significant new questions about the prevailing understanding of how cytokines, via iNOS, cause cardiac dysfunction and injury in vivo during cardiac inflammatory disease states since cardiac myocytes are not a major source of high NO production.

scholarly journals Janus Kinase 1 Is Essential for Inflammatory Cytokine Signaling and Mammary Gland Remodeling

2016 ◽  
Vol 36 (11) ◽  
pp. 1673-1690 ◽  
Author(s):  
Kazuhito Sakamoto ◽  
Barbara L. Wehde ◽  
Kyung Hyun Yoo ◽  
Taemook Kim ◽  
Nirakar Rajbhandari ◽  
...  
Keyword(s):  
Cell Death ◽  
Mammary Gland ◽  
Tyrosine Kinase ◽  
Inflammatory Cytokine ◽  
Target Genes ◽  
Mammary Epithelium ◽  
Janus Kinase ◽  
Cytokine Signaling ◽  
Double Knockout ◽  
Downstream Effector

Despite a wealth of knowledge about the significance of individual signal transducers and activators of transcription (STATs), essential functions of their upstream Janus kinases (JAKs) during postnatal development are less well defined. Using a novel mammary gland-specific JAK1 knockout model, we demonstrate here that this tyrosine kinase is essential for the activation of STAT1, STAT3, and STAT6 in the mammary epithelium. The loss of JAK1 uncouples interleukin-6-class ligands from their downstream effector, STAT3, which leads to the decreased expression of STAT3 target genes that are associated with the acute-phase response, inflammation, and wound healing. Consequently, JAK1-deficient mice exhibit impaired apoptosis and a significant delay in mammary gland remodeling. Using RNA sequencing, we identified several new JAK1 target genes that are upregulated during involution. These includeBmfandBim, which are known regulators of programmed cell death. Using a BMF/BIM-double-knockout epithelial transplant model, we further validated that the synergistic action of these proapoptotic JAK1 targets is obligatory for the remodeling of the mammary epithelium. The collective results of this study suggest that JAK1 has nonredundant roles in the activation of particular STAT proteins and this tyrosine kinase is essential for coupling inflammatory cytokine signals to the cell death machinery in the differentiated mammary epithelium.

Involvement of the CDK2-E2F1 pathway in cisplatin cytotoxicity in vitro and in vivo

2007 ◽  
Vol 293 (1) ◽  
pp. F52-F59 ◽  
Author(s):  
Fang Yu ◽  
Judit Megyesi ◽  
Robert L. Safirstein ◽  
Peter M. Price
Keyword(s):  
Cell Death ◽  
Cell Cycle Progression ◽  
Physical Interaction ◽  
Downstream Effector ◽  
Cdk2 Activity ◽  
Histological Criteria ◽  
Proximal Tubular ◽  
Induced Apoptosis

E2F1 is a key regulator that links cell cycle progression and cell death. E2F1 activity is controlled by Cdk2-cyclin complexes via several mechanisms, such as phosphorylation of retinoblastoma protein (pRb) to release E2F1, direct phosphorylation, and stable physical interaction. We have demonstrated that cisplatin cytotoxicity depends on Cdk2 activity, and Cdk2 inhibition protects kidney cells from cisplatin-induced cell death in vitro and in vivo. Now we show that E2F1 is an important downstream effector of Cdk2 that accumulates in mouse kidneys and in cultured mouse proximal tubular cells (TKPTS) after cisplatin exposure by a Cdk2-dependent mechanism. Direct inhibition of E2F1 by transduction with adenoviruses expressing an E2F1-binding protein (TopBP1) protected TKPTS cells from cisplatin-induced apoptosis, whereas overexpression of E2F1 caused cell death. Moreover, E2F1 knockout mice were markedly protected against cisplatin nephrotoxicity by both functional and histological criteria. Collectively, cisplatin-induced cell death is dependent on Cdk2 activity, which is at least partly through the Cdk2-E2F1 pathway both in vitro and in vivo.

β-Adrenergic receptor/cAMP-mediated signaling and apoptosis of S49 lymphoma cells

2000 ◽  
Vol 279 (5) ◽  
pp. C1665-C1674 ◽  
Author(s):  
Lizhen Yan ◽  
Volker Herrmann ◽  
Jason K. Hofer ◽  
Paul A. Insel
Keyword(s):  
Cell Death ◽  
Adrenergic Receptor ◽  
Functional Protein ◽  
Apoptotic Pathway ◽  
Mediated Effects ◽  
T Lymphoma ◽  
Induced Apoptosis ◽  
Camp Levels ◽  
Promote Cell Death

β-Adrenergic receptor (βAR) activation and/or increases in cAMP regulate growth and proliferation of a variety of cells and, in some cells, promote cell death. In the current studies we addressed the mechanism of this growth reduction by examining βAR-mediated effects in the murine T-lymphoma cell line S49. Wild-type S49 cells, derived from immature thymocytes (CD4+/CD8+) undergo growth arrest and subsequent death when treated with agents that increase cAMP levels (e.g., βAR agonists, 8-bromo-cAMP, cholera toxin, forskolin). Morphological and biochemical criteria indicate that this cell death is a result of apoptosis. In cyc−and kin−S49 cells, which lack Gsα and functional protein kinase A (PKA), respectively, βAR activation of Gsα and cAMP action via PKA are critical steps in this apoptotic pathway. S49 cells that overexpress Bcl-2 are resistant to cAMP-induced apoptosis. We conclude that βAR activation induces apoptosis in immature T lymphocytes via Gsα and PKA, while overexpression of Bcl-2 prevents cell death. βAR/cAMP/PKA-mediated apoptosis may provide a means to control proliferation of immature T cells in vivo.

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