scholarly journals Pyruvate restores β-adrenergic sensitivity of L-type Ca2+ channels in failing rat heart: role of protein phosphatase

2013 ◽  
Vol 304 (10) ◽  
pp. H1352-H1360 ◽  
Author(s):  
Ming-Qi Zheng ◽  
Xun Li ◽  
Kang Tang ◽  
Neeru M. Sharma ◽  
Todd A. Wyatt ◽  
...  
Keyword(s):  
Heart Failure ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Ventricular Myocytes ◽  
Intracellular Camp ◽  
Adrenergic Stimulation ◽  
Thioredoxin System ◽  
Kinase A

Oxidative stress plays a major role in the pathogenesis of heart failure, where the contractile response to β-adrenergic stimulation is profoundly depressed. This condition involves L-type Ca2+ channels, but the mechanisms underlying their impaired adrenergic regulation are unclear. Thus the present study explored the basis for impaired adrenergic control of Ca2+ channels in a rat infarction model of heart failure. Patch-clamp recordings of L-type Ca2+ current ( ICa,L) from ventricular myocytes isolated from infarcted hearts showed a blunted response to intracellular cAMP that was reversed by treatment with exogenous pyruvate. Biochemical studies showed that basal and cAMP-stimulated protein kinase A activities were similar in infarcted and sham-operated hearts, whereas molecular analysis also found that binding of protein kinase A to the α1C subunit of voltage-gated Ca2+ channel isoform 1.2 was not different between groups. By contrast, protein phosphatase 2A (PP2A) activity and binding to α1C were significantly less in infarcted hearts. The PP2A inhibitor okadaic acid markedly increased ICa,L in sham-operated myocytes, but this response was significantly less in myocytes from infarcted hearts. However, pyruvate normalized ICa,L stimulation by okadaic acid, and this effect was blocked by inhibitors of thioredoxin reductase, implicating a functional role for the redox-active thioredoxin system. Our data suggest that blunted β-adrenergic stimulation of ICaL in failing hearts results from hyperphosphorylation of Ca2+ channels secondary to oxidation-induced impairment of PP2A function. We propose that the redox state of Ca2+ channels or PP2A is controlled by the thioredoxin system which plays a key role in Ca2+ channel remodeling of the failing heart.

cAMP-positive regulation of angiotensinogen gene expression and protein secretion in rat adipose tissue

2004 ◽  
Vol 286 (3) ◽  
pp. E434-E438 ◽  
Author(s):  
Valérie Serazin ◽  
Marie-Noelle Dieudonné ◽  
Mireille Morot ◽  
Philippe de Mazancourt ◽  
Yves Giudicelli
Keyword(s):  
Adipose Tissue ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Secretion ◽  
Intracellular Camp ◽  
Pathological State ◽  
Mrna Levels ◽  
Adrenergic Stimulation ◽  
Rat Adipose Tissue ◽  
Kinase A

The adipose renin-angiotensin system (RAS) has been assigned to participate in the control of adipose tissue development and in the pathogenesis of obesity-related hypertension. In adipose cells, the biological responses to β-adrenergic stimulation are mediated by an increase in intracellular cAMP. Because cAMP is known to promote adipogenesis and because an association exists between body fat mass, hypertension, and increased sympathetic stimulation, we examined the influence of cAMP on angiotensinogen (ATG) expression and secretion in rat adipose tissue. Exposure of primary cultured differentiated preadipocytes to the cAMP analog 8-bromoadenosine 3′,5′-cyclic monophosphate (8-BrcAMP) or cAMP-stimulating agents (forskolin and IBMX) results in a significant increase in ATG mRNA levels. In adipose tissue fragments, 8-BrcAMP also increases ATG mRNA levels and protein secretion, but not in the presence of the protein kinase A inhibitor H89. The addition of isoproterenol, known to stimulate the synthesis of intracellular cAMP via β-adrenoreceptors, had the same stimulatory effect on ATG expression and secretion. These results indicate that cAMP in vitro upregulates ATG expression and secretion in rat adipose tissue via the protein kinase A-dependent pathway. Further studies are required to determine whether this regulatory pathway is activated in human obesity, where increased sympathetic tone is frequently observed, and to elucidate the importance of adipose ATG to the elevated blood pressure observed in this pathological state.

Positive and negative effects of nitric oxide on Ca2+ sparks: influence of β-adrenergic stimulation

2001 ◽  
Vol 281 (6) ◽  
pp. H2295-H2303 ◽  
Author(s):  
Mark T. Ziolo ◽  
Hideki Katoh ◽  
Donald M. Bers
Keyword(s):  
Nitric Oxide ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Ventricular Myocytes ◽  
Cardiac Contractility ◽  
Adrenergic Stimulation ◽  
High Concentration ◽  
Negative Effects ◽  
Dual Effect ◽  
Kinase A

Nitric oxide (NO) can have a positive or negative effect on cardiac contractility and the ryanodine receptor (RyR). This dual effect has been explained as being dependent on the concentration of NO. We find that cellular RyR response to NO is also dependent on the degree of β-adrenergic stimulation, and thus the state of protein kinase A activation. Ca2+ spark frequency (CaSpF) in rat ventricular myocytes was used as an index of resting RyR activity. CaSpF response to β-adrenergic stimulation was used as an index of protein kinase A activation. High concentration of isoproterenol, a β-adrenergic agonist, caused a large increase in CaSpF; addition of NO (spermine NONOate, 300 μM) then caused a decrease in CaSpF. Low concentration of isoproterenol produced only a slight increase in CaSpF, but the same NO concentration now caused a large increase in CaSpF. A dual effect was also observed in twitch. Thus the net direction of the effects of NO on RyR activity and Ca2+transients (directly or by alteration of sarcoplasmic reticulum Ca2+ load) can be reversed, depending on the ambient level of β-adrenergic activation.

Nuclear protein phosphatase 2A dephosphorylates protein kinase A-phosphorylated CREB and regulates CREB transcriptional stimulation

1993 ◽  
Vol 13 (5) ◽  
pp. 2822-2834
Author(s):  
B E Wadzinski ◽  
W H Wheat ◽  
S Jaspers ◽  
L F Peruski ◽  
R L Lickteig ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Nuclear Protein ◽  
Dibutyryl Camp ◽  
Nuclear Extracts ◽  
Phosphorylated Creb ◽  
Kinase A

Cyclic AMP (cAMP)-dependent protein kinase A (PKA) stimulates the transcription of many eucaryotic genes by catalyzing the phosphorylation of the cAMP-regulatory element binding protein (CREB). Conversely, the attenuation or inhibition of cAMP-stimulated gene transcription would require the dephosphorylation of CREB by a nuclear protein phosphatase. In HepG2 cells treated with the protein serine/threonine (Ser/Thr) phosphatase inhibitor okadaic acid, dibutyryl-cAMP-stimulated transcription from the phosphoenolpyruvate carboxykinase (PEPCK) promoter was enhanced over the level of PEPCK gene transcription observed in cells treated with dibutyryl-cAMP alone. This process was mediated, at least in part, by a region of the PEPCK promoter that binds CREB. Likewise, okadaic acid prevents the dephosphorylation of PKA-phosphorylated CREB in rat liver nuclear extracts and enhances the ability of PKA to stimulate transcription from the PEPCK promoter in cell-free reactions. The ability of okadaic acid to enhance PKA-stimulated transcription in vitro was entirely dependent on the presence of CREB in the reactions. The phospho-CREB (P-CREB) phosphatase activity present in nuclear extracts coelutes with protein Ser/Thr phosphatase type 2A (PP2A) on Mono Q, amino-hexyl Sepharose, and heparin agarose columns and was chromatographically resolved from nuclear protein Ser/Thr-phosphatase type 1 (PP1). Furthermore, P-CREB phosphatase activity in nuclear extracts was unaffected by the heat-stable protein inhibitor-2, which is a potent and selective inhibitor of PP1. Nuclear PP2A dephosphorylated P-CREB 30-fold more efficiently than did nuclear PP1. Finally, when PKA-phosphorylated CREB was treated with immunopurified PP2A and PP1, the PP2A-treated CREB did not stimulate transcription from the PEPCK promoter in vitro, whereas the PP1-treated CREB retained the ability to stimulate transcription. Nuclear PP2A appears to be the primary phosphatase that dephosphorylates PKA-phosphorylated CREB.

scholarly journals Ser-2030, but not Ser-2808, is the major phosphorylation site in cardiac ryanodine receptors responding to protein kinase A activation upon β-adrenergic stimulation in normal and failing hearts

2006 ◽  
Vol 396 (1) ◽  
pp. 7-16 ◽  
Author(s):  
Bailong Xiao ◽  
Guofeng Zhong ◽  
Masakazu Obayashi ◽  
Dongmei Yang ◽  
Keyun Chen ◽  
...  
Keyword(s):  
Heart Failure ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Ryanodine Receptors ◽  
Phosphorylation Site ◽  
Specific Inhibitor ◽  
Dependent Manner ◽  
Adrenergic Stimulation ◽  
Rat Hearts ◽  
Kinase A

We have recently shown that RyR2 (cardiac ryanodine receptor) is phosphorylated by PKA (protein kinase A/cAMP-dependent protein kinase) at two major sites, Ser-2030 and Ser-2808. In the present study, we examined the properties and physiological relevance of phosphorylation of these two sites. Using site- and phospho-specific antibodies, we demonstrated that Ser-2030 of both recombinant and native RyR2 from a number of species was phosphorylated by PKA, indicating that Ser-2030 is a highly conserved PKA site. Furthermore, we found that the phosphorylation of Ser-2030 responded to isoproterenol (isoprenaline) stimulation in rat cardiac myocytes in a concentration- and time-dependent manner, whereas Ser-2808 was already substantially phosphorylated before β-adrenergic stimulation, and the extent of the increase in Ser-2808 phosphorylation after β-adrenergic stimulation was much less than that for Ser-2030. Interestingly, the isoproterenol-induced phosphorylation of Ser-2030, but not of Ser-2808, was markedly inhibited by PKI, a specific inhibitor of PKA. The basal phosphorylation of Ser-2808 was also insensitive to PKA inhibition. Moreover, Ser-2808, but not Ser-2030, was stoichiometrically phosphorylated by PKG (protein kinase G). In addition, we found no significant phosphorylation of RyR2 at the Ser-2030 PKA site in failing rat hearts. Importantly, isoproterenol stimulation markedly increased the phosphorylation of Ser-2030, but not of Ser-2808, in failing rat hearts. Taken together, these observations indicate that Ser-2030, but not Ser-2808, is the major PKA phosphorylation site in RyR2 responding to PKA activation upon β-adrenergic stimulation in both normal and failing hearts, and that RyR2 is not hyperphosphorylated by PKA in heart failure. Our results also suggest that phosphorylation of RyR2 at Ser-2030 may be an important event associated with altered Ca2+ handling and cardiac arrhythmia that is commonly observed in heart failure upon β-adrenergic stimulation.

scholarly journals Nuclear protein phosphatase 2A dephosphorylates protein kinase A-phosphorylated CREB and regulates CREB transcriptional stimulation.

1993 ◽  
Vol 13 (5) ◽  
pp. 2822-2834 ◽  
Author(s):  
B E Wadzinski ◽  
W H Wheat ◽  
S Jaspers ◽  
L F Peruski ◽  
R L Lickteig ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Nuclear Protein ◽  
Dibutyryl Camp ◽  
Nuclear Extracts ◽  
Phosphorylated Creb ◽  
Kinase A

Cyclic AMP (cAMP)-dependent protein kinase A (PKA) stimulates the transcription of many eucaryotic genes by catalyzing the phosphorylation of the cAMP-regulatory element binding protein (CREB). Conversely, the attenuation or inhibition of cAMP-stimulated gene transcription would require the dephosphorylation of CREB by a nuclear protein phosphatase. In HepG2 cells treated with the protein serine/threonine (Ser/Thr) phosphatase inhibitor okadaic acid, dibutyryl-cAMP-stimulated transcription from the phosphoenolpyruvate carboxykinase (PEPCK) promoter was enhanced over the level of PEPCK gene transcription observed in cells treated with dibutyryl-cAMP alone. This process was mediated, at least in part, by a region of the PEPCK promoter that binds CREB. Likewise, okadaic acid prevents the dephosphorylation of PKA-phosphorylated CREB in rat liver nuclear extracts and enhances the ability of PKA to stimulate transcription from the PEPCK promoter in cell-free reactions. The ability of okadaic acid to enhance PKA-stimulated transcription in vitro was entirely dependent on the presence of CREB in the reactions. The phospho-CREB (P-CREB) phosphatase activity present in nuclear extracts coelutes with protein Ser/Thr phosphatase type 2A (PP2A) on Mono Q, amino-hexyl Sepharose, and heparin agarose columns and was chromatographically resolved from nuclear protein Ser/Thr-phosphatase type 1 (PP1). Furthermore, P-CREB phosphatase activity in nuclear extracts was unaffected by the heat-stable protein inhibitor-2, which is a potent and selective inhibitor of PP1. Nuclear PP2A dephosphorylated P-CREB 30-fold more efficiently than did nuclear PP1. Finally, when PKA-phosphorylated CREB was treated with immunopurified PP2A and PP1, the PP2A-treated CREB did not stimulate transcription from the PEPCK promoter in vitro, whereas the PP1-treated CREB retained the ability to stimulate transcription. Nuclear PP2A appears to be the primary phosphatase that dephosphorylates PKA-phosphorylated CREB.

scholarly journals Protein kinase A activates protein phosphatase 2A by phosphorylation of the B56  subunit

2007 ◽  
Vol 104 (8) ◽  
pp. 2979-2984 ◽  
Author(s):  
J.-H. Ahn ◽  
T. McAvoy ◽  
S. V. Rakhilin ◽  
A. Nishi ◽  
P. Greengard ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Phosphatase 2A ◽  
Kinase A

Regulation of NF-κB activation by protein phosphatase 2B and NO, via protein kinase A activity, in human monocytes

Nitric Oxide ◽  
2003 ◽  
Vol 8 (1) ◽  
pp. 65-74 ◽  
Author(s):  
M Teresa Bengoechea-Alonso ◽  
Beatriz Pelacho ◽  
Juan A Osés-Prieto ◽  
Esteban Santiago ◽  
Natalia López-Moratalla ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Phosphatase ◽  
Human Monocytes ◽  
Protein Phosphatase 2B ◽  
Kinase A

Interleukin-1 alpha stimulates dopamine release by activating type II protein kinase A in PC-12 cells

1995 ◽  
Vol 269 (6) ◽  
pp. E1083-E1088
Author(s):  
A. Joseph ◽  
A. Kumar ◽  
N. A. O'Connell ◽  
R. K. Agarwal ◽  
A. R. Gwosdow
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Dopamine Release ◽  
Interleukin 1 ◽  
Intracellular Camp ◽  
Type I ◽  
Camp Accumulation ◽  
Type Ii ◽  
Pc 12 Cells ◽  
Kinase A

A recent study from this laboratory [A. R. Gwosdow, N. A. O'Connell, and A. B. Abou-Samra. Am. J. Physiol. 263 (Endocrinol. Metab. 26): E461-E466, 1992] showed that the inflammatory mediator interleukin-1 alpha (IL-1 alpha) stimulates catecholamine release from primary cultures of rat adrenal cells. The present studies were conducted to determine whether 1) IL-1 alpha stimulates catecholamine/dopamine release from the adrenal medullary cell line PC-12 and 2) the adenosine 3',5'-cyclic monophosphate (cAMP)-protein kinase A (PKA) pathway is involved in IL-1 alpha-induced dopamine release from PC-12 cells. The results indicate that IL-1 alpha significantly (P < 0.05) elevated dopamine release after a 24-h incubation period. IL-1 alpha did not stimulate cAMP accumulation at any time period between 5 min and 2 h. In contrast, forskolin-treated cells elevated (P < 0.05) intracellular cAMP levels and increased dopamine release. Because IL-1 alpha did not affect cAMP accumulation, the effect of IL-1 alpha on PKA activity was investigated. IL-1 alpha increased (P < 0.05) PKA activity at 15 and 30 min and returned to control levels by 1 h. Forskolin also increased (P < 0.05) PKA activity. The type of PKA activated (P < 0.05) by IL-1 alpha was type II PKA. In contrast, forskolin activated (P < 0.05) type I and type II PKA. Inhibition of PKA with the PKA inhibitor H-8 blocked PKA activity and dopamine secretion by both IL-1 alpha and forskolin in PC-12 cells. These observations demonstrate that 1) IL-1 alpha stimulated dopamine release from PC-12 cells by activating PKA, 2) the mechanism of IL-1 alpha activation of PKA does not involve detectable increases in intracellular cAMP accumulation, and 3) IL-1 alpha activates type II PKA, which is used by IL-1 alpha to stimulate dopamine secretion from PC-12 cells.

Interaction Between Protein Kinase A (PKA) and Protein Phosphatase PP2A During Human Sperm Capacitation.

2012 ◽  
Vol 87 (Suppl_1) ◽  
pp. 448-448
Author(s):  
Patricio J. Morales ◽  
Kely Ordenes ◽  
Lidia Zuñiga ◽  
Emilce S. Diaz
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Phosphatase ◽  
Human Sperm ◽  
Sperm Capacitation ◽  
Kinase A
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