β-Adrenergic and antiadrenergic modulation of cardiac adenylyl cyclase is influenced by phosphorylation

Dobson, James G.; Shea, Lynne G.; Fenton, Richard A.

doi:10.1152/ajpheart.00950.2002

Cited by 9 publications

(12 citation statements)

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“…Approximately 5 mg of protein was subjected to 12% PAGE, as previously described (Dobson et al, 2003). Separated proteins were transferred to nitrocellulose membranes and the latter were exposed to a polyclonal rabbit anti-PP2A C-subunit (1 ng/ml; Upstate).…”

Section: Page and Immunoblottingmentioning

confidence: 99%

“…These include proteins such as troponin I, phospholamban and others that are involved in force development, calcium homeostasis, and mechanisms of receptor signaling (Stull, 1980;Fenton and Dobson, 1984;Vittone et al, 1990;Hain et al, 1995;Dobson et al, 2003;Terentyev et al, 2003). The antiadrenergic action of A 1 R has been shown to reduce the level of phosphorylation attained by a number of cellular proteins during adrenergic activation (Fenton and Dobson, 1984;George et al, 1991;Gupta et al, 1993;Liu and Hofmann, 2002).…”

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confidence: 99%

“…Pharmacological inhibition of protein phosphatases with inhibitors such as cantharidin has been shown to result in enhanced phosphorylation and increased contractile force in myocardial preparations (Neumann et al, , 1995Knapp et al, 1998;Narayan et al, 2000;duBell et al, 2002). In addition, studies have demonstrated that while overexpression of the catalytic unit of the serine/threonine protein phosphatase 2A (PP2A) impairs cardiac function (Gergs et al, 2004), elevated expression of protein phosphatase inhibitors PPI-1 and PPI-2 results in cardiac function enhancement (Kirchhefer et al, 2005;Pathak et al, 2005).…”

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Adenosine A₁ and A_2A receptor regulation of protein phosphatase 2A in the murine heart

Tikh

Fenton

Chen

et al. 2008

Journal Cellular Physiology

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Adenosine plays a role in regulating the contractile function of the heart. This includes a positive ionotropic action via the adenosine A(2A) receptor (A(2A)R) and an inhibition of beta(1)-adrenergic receptor-induced ionotropy (antiadrenergic action) via the adenosine A(1) receptor (A(1)R). Phosphatase activity has also been shown to influence contractile function by affecting the level of protein phosphorylation. Protein phosphatase 2A (PP2A) plays a significant role in mediating the A(1)R antiadrenergic effect. The purpose of this study was to investigate the effects of A(2A)R and A(1)R on the activities of PP2A in hearts obtained from wild-type (WT) and A(2A)R knockout (A(2A)R-KO) mice. PP2A activities were examined in myocardial particulate and cytoplasmic extract fractions. Treatment of wild-type hearts with the A(1)R agonist CCPA increased the total PP2A activity and increased the particulate:cytoplasmic PP2A activity ratio. Treatment with the A(2A)R agonist CGS-21680 (CGS) decreased the total PP2A activity and decreased the particulate:cytoplasmic PP2A activity ratio. This indicated a movement of PP2A activity between cell fractions. The effect of CCPA was inhibited by CGS. In A(2A)R-KO hearts the response to A(1)R activation was markedly enhanced whereas the response to A(2A)R activation was absent. These data show that A(2A)R and A(1)R regulate PP2A activity, thus suggesting an important mechanism for modulating myocardial contractility.

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Adenosine A₁ and A_2A receptor regulation of protein phosphatase 2A in the murine heart

Tikh

Fenton

Chen

et al. 2008

Journal Cellular Physiology

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“…Ventricular myocytes were dissolved and subjected to PAGE and immunoblotting as previously described (14). Primary rabbit PKC⑀ and PKC␦ antibodies were used and visualized with a secondary anti-rabbit antibody conjugated to horseradish peroxidase.…”

Section: Isolation Of Ventricular Myocytesmentioning

confidence: 99%

Protein kinase Cε and the antiadrenergic action of adenosine in rat ventricular myocytes

Miyazaki

Komatsu

Ikebe

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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Miyazaki, Koji, Satoshi Komatsu, Mitsuo Ikebe, Richard A. Fenton, and James G. Dobson, Jr. Protein kinase C⑀ and the antiadrenergic action of adenosine in rat ventricular myocytes. Am J Physiol Heart Circ Physiol 287: H1721-H1729, 2004. First published June 17, 2004 10.1152/ajpheart.00224.2004.-Adenosine-induced antiadrenergic effects in the heart are mediated by adenosine A1 receptors (A1R). The role of PKC⑀ in the antiadrenergic action of adenosine was explored with adult rat ventricular myocytes in which PKC⑀ was overexpressed. Myocytes were transfected with a pEGFP-N1 vector in the presence or absence of a PKC⑀ construct and compared with normal myocytes. The extent of myocyte shortening elicited by electrical stimulation of quiescent normal and transfected myocytes was recorded with video imaging. PKC⑀ was found localized primarily in transverse tubules. The A1R agonist chlorocyclopentyladenosine (CCPA) at 1 M rendered an enhanced localization of PKC⑀ in the t-tubular system. The ␤-adrenergic agonist isoproterenol (Iso; 0.4 M) elicited a 29 -36% increase in myocyte shortening in all three groups. Although CCPA significantly reduced the Isoproduced increase in shortening in all three groups, the reduction caused by CCPA was greatest with PKC⑀ overexpression. The CCPA reduction of the Iso-elicited shortening was eliminated in the presence of a PKC⑀ inhibitory peptide. These results suggest that the translocation of PKC⑀ to the t-tubular system plays an important role in A 1R-mediated antiadrenergic actions in the heart. ␤-adrenergic; cardiomyocyte shortening; transfection; t tubules; PKC⑀ translocation ADENOSINE is known to exert numerous effects in the heart. This endogenous nucleoside via adenosine A 1 receptors (A 1 R) causes antiadrenergic (12), antiarrthymogenic (7, 19), and preconditioning (15, 17) actions in the myocardium. The antiadrenergic action of adenosine involves reductions in ␤-adrenergic catecholamine-induced increases in adenylyl cyclase activity (30,43,45), cAMP formation (10, 51), PKA activation (12), myocardial protein phosphorylation (18), intracellular Ca 2ϩ transient magnitude (19), and cardiac atrial (11, 42) and ventricular (12,46,51) contractility. Both the A 1 R-mediated antiadrenergic actions (40) and preconditioning (29, 49) appear to involve PKC activity. There are at least 12 isoforms of PKC known to exist in tissues (35), and activation fosters their translocation to anchor proteins in various subcellular locations (37). PKC⑀ along with PKC-␣ and PKC␦ are the dominant isoforms present in adult rat cardiomyocytes (9, 47). Because A 1 R stimulation has been reported to activate PKC␦ in freshly isolated rat ventricular myocytes (22), the possibility that this adenosine receptor activates PKC⑀ was explored.The present study was undertaken to ascertain whether PKC⑀ plays a role in the antiadrenergic effects caused by A 1 R stimulation. This possibility was investigated by overexpressing PKC⑀ in isolated primary cultured rat ventricular myocytes and determining whether the enzyme...

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“…Alternative mechanisms not involving p38 MAPK by which adenosine manifests its action may be involved. These include the well-described inhibitory effect of adenosine on adrenergic-stimulated adenylyl cyclase (6,7) or the adenosine-induced activation of protein phosphatase 2A (26,41).…”

Section: Discussionmentioning

confidence: 99%

Myocardial adenosine A₁-receptor-mediated adenoprotection involves phospholipase C, PKC-ε, and p38 MAPK, but not HSP27

Fenton

Shea

Doddi

et al. 2010

American Journal of Physiology-Heart and Circulatory Physiology

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Adenosine via an adenosine A1 receptor (A1R) is a negative feedback inhibitor of adrenergic stimulation in the heart, protecting it from toxic effects of overstimulation. Stimulation of the A 1R results in the activation of Gi protein, release of free G␤␥-subunits, and activation/translocation of PKC-ε to the receptor for activated C kinase 2 protein at the Z-line of the cardiomyocyte sarcomere. Using an anti-G␤␥ peptide, we investigated the role of these subunits in the A1R stimulation of phospholipase C (PLC), with the premise that the resulting diacylglycerol provides for the activation of PKC-ε. Inositol 1,4,5-triphosphate release was an index of PLC activity. Chlorocyclopentyl adenosine (CCPA), an A1R agonist, increased inositol 1,4,5-triphosphate production by 273% in mouse heart homogenates, an effect absent in A1R knockout hearts and inhibited by anti-G␤␥ peptide. In a second study, p38 MAPK and heat shock protein 27 (HSP27), found by others to be associated with the loss of myocardial contractile function, were postulated to play a role in the actions of A1R. Isoproterenol, a ␤-adrenergic receptor agonist, increased the Ca 2ϩ transient and sarcomere shortening magnitudes by 36 and 49%, respectively. In the rat cardiomyocyte, CCPA significantly reduced these increases, an action blocked by the p38 MAPK inhibitor SB-203580. While CCPA significantly increased the phosphorylation of HSP27, this action was inhibited by isoproterenol. These data indicate that the activation of PKC-ε by A1R results from the activation of PLC via free G␤␥-subunits released upon A1R-induced dissociation of Gi␣␤␥. Attenuation of ␤-adrenergic-induced contractile function by A1R may involve the activation of p38 MAPK, but not HSP27. G␤␥ subunits; antiadrenergic; rodent; contractility ADENOSINE IS RELEASED ENDOGENOUSLY in the heart that is stressed by hypoxia, ischemia, or adrenergic stimulation (13,15). In the interstitium, adenosine activates cell surface receptors that initiate signal cascades within the cardiomyocyte, ultimately reducing the cardiotoxic manifestations of the initial insult (16,43). For many years, study has focused on the antiadrenergic action of adenosine, or the ability of this nucleoside to protect the heart against excessive stimulation (34) by norepinephrine released during ischemia (36). In manifesting this action, adenosine A 1 receptors (A 1 R) attenuate ␤-adrenergic catecholamine-elicited increases in G s protein cycling (17), adenylyl cyclase activity (33), cAMP formation (5), activation of protein kinase A (PKA) (6), protein phosphorylation (12), myocardial Ca 2ϩ transient magnitude (14), and ventricular contractility (6, 16).Adenosine also reduces the responsiveness of the myocardium to catecholamine stimulation by a mechanism independent of changes in adrenergic-stimulated cyclase activity. This adenoprotection by the A 1 R agonist chlorocyclopentyl adenosine (CCPA) has been demonstrated by us to involve the translocation of PKC-ε to receptor for activated C kinase 2 (RACK2) in rat and mouse myocard...

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β-Adrenergic and antiadrenergic modulation of cardiac adenylyl cyclase is influenced by phosphorylation

Cited by 9 publications

References 29 publications

Adenosine A₁ and A_2A receptor regulation of protein phosphatase 2A in the murine heart

Adenosine A₁ and A_2A receptor regulation of protein phosphatase 2A in the murine heart

Protein kinase Cε and the antiadrenergic action of adenosine in rat ventricular myocytes

Myocardial adenosine A₁-receptor-mediated adenoprotection involves phospholipase C, PKC-ε, and p38 MAPK, but not HSP27

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β-Adrenergic and antiadrenergic modulation of cardiac adenylyl cyclase is influenced by phosphorylation

Cited by 9 publications

References 29 publications

Adenosine A1 and A2A receptor regulation of protein phosphatase 2A in the murine heart

Adenosine A1 and A2A receptor regulation of protein phosphatase 2A in the murine heart

Protein kinase Cε and the antiadrenergic action of adenosine in rat ventricular myocytes

Myocardial adenosine A1-receptor-mediated adenoprotection involves phospholipase C, PKC-ε, and p38 MAPK, but not HSP27

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Adenosine A₁ and A_2A receptor regulation of protein phosphatase 2A in the murine heart

Adenosine A₁ and A_2A receptor regulation of protein phosphatase 2A in the murine heart

Myocardial adenosine A₁-receptor-mediated adenoprotection involves phospholipase C, PKC-ε, and p38 MAPK, but not HSP27