Protein kinase A–dependent modulation of Ca2+ sensitivity in cardiac and fast skeletal muscles after reconstitution with cardiac troponin

Protein kinase A (PKA)-dependent phosphorylation of troponin (Tn)I represents a major physiological mechanism during β-adrenergic stimulation in myocardium for the reduction of myofibrillar Ca2+ sensitivity via weakening of the interaction with TnC. By taking advantage of thin filament reconstitution, we directly investigated whether or not PKA-dependent phosphorylation of cardiac TnI (cTnI) decreases Ca2+ sensitivity in different types of muscle: cardiac (porcine ventricular) and fast skeletal (rabbit psoas) muscles. PKA enhanced phosphorylation of cTnI at Ser23/24 in skinned cardiac muscle and decreased Ca2+ sensitivity, of which the effects were confirmed after reconstitution with the cardiac Tn complex (cTn) or the hybrid Tn complex (designated as PCRF; fast skeletal TnT with cTnI and cTnC). Reconstitution of cardiac muscle with the fast skeletal Tn complex (sTn) not only increased Ca2+ sensitivity, but also abolished the Ca2+-desensitizing effect of PKA, supporting the view that the phosphorylation of cTnI, but not that of other myofibrillar proteins, such as myosin-binding protein C, primarily underlies the PKA-induced Ca2+ desensitization in cardiac muscle. Reconstitution of fast skeletal muscle with cTn decreased Ca2+ sensitivity, and PKA further decreased Ca2+ sensitivity, which was almost completely restored to the original level upon subsequent reconstitution with sTn. The essentially same result was obtained when fast skeletal muscle was reconstituted with PCRF. It is therefore suggested that the PKA-dependent phosphorylation or dephosphorylation of cTnI universally modulates Ca2+ sensitivity associated with cTnC in the striated muscle sarcomere, independent of the TnT isoform.

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

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00188.2003 ◽

2004 ◽

Vol 286 (3) ◽

pp. E434-E438 ◽

Cited By ~ 9

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.

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Stress-induced increase in skeletal muscle force requires protein kinase A phosphorylation of the ryanodine receptor

The Journal of Physiology ◽

10.1113/jphysiol.2012.237925 ◽

2012 ◽

Vol 590 (24) ◽

pp. 6381-6387 ◽

Cited By ~ 37

Author(s):

Daniel C. Andersson ◽

Matthew J. Betzenhauser ◽

Steven Reiken ◽

Alisa Umanskaya ◽

Takayuki Shiomi ◽

...

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Protein Kinase A ◽

Ryanodine Receptor ◽

Muscle Force ◽

Kinase A

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Pre-exposure to adenosine, acting via A2Areceptors on endothelial cells, alters the protein kinase A dependence of adenosine-induced dilation in skeletal muscle resistance arterioles

The Journal of Physiology ◽

10.1113/jphysiol.2013.265835 ◽

2014 ◽

Vol 592 (12) ◽

pp. 2575-2590 ◽

Cited By ~ 8

Author(s):

Nir Maimon ◽

Patricia A. Titus ◽

Ingrid H. Sarelius

Keyword(s):

Skeletal Muscle ◽

Endothelial Cells ◽

Protein Kinase ◽

Protein Kinase A ◽

Kinase A

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Myosin Binding Protein-C Slow is a Novel Substrate for Protein Kinase A (PKA) and C (PKC) in Skeletal Muscle

Journal of Proteome Research ◽

10.1021/pr200355w ◽

2011 ◽

Vol 10 (10) ◽

pp. 4547-4555 ◽

Cited By ~ 28

Author(s):

Maegen A. Ackermann ◽

Aikaterini Kontrogianni-Konstantopoulos

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Protein Kinase A ◽

Protein C ◽

Binding Protein ◽

Myosin Binding Protein ◽

Myosin Binding Protein C ◽

Myosin Binding ◽

Kinase A

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

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.281.6.h2295 ◽

2001 ◽

Vol 281 (6) ◽

pp. H2295-H2303 ◽

Cited By ~ 41

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.

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Intracellular Distribution of Mammalian Protein Kinase a Catalytic Subunit Altered by Conserved Asn2 Deamidation

The Journal of Cell Biology ◽

10.1083/jcb.148.4.715 ◽

2000 ◽

Vol 148 (4) ◽

pp. 715-726 ◽

Cited By ~ 47

Author(s):

Rainer Pepperkok ◽

Agnes Hotz-Wagenblatt ◽

Norbert König ◽

Andreas Girod ◽

Dirk Bossemeyer ◽

...

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Striated Muscle ◽

Human Cell Line ◽

Intracellular Distribution ◽

Signaling Proteins ◽

C Subunit ◽

Nih 3T3 ◽

Kinase A

The catalytic (C) subunit of protein kinase A functions both in the cytoplasm and the nucleus. A major charge variant representing about one third of the enzyme in striated muscle results from deamidation in vivo of the Asn2 residue at the conserved NH2-terminal sequence myrGly-Asn-Ala (Jedrzejewski, P.T., A. Girod, A. Tholey, N. König, S. Thullner, V. Kinzel, and D. Bossemeyer. 1998. Protein Sci. 7:457–469). Because of the increase of electronegativity by generation of Asp2, it is reminiscent of a myristoyl-electrostatic switch. To compare the intracellular distribution of the enzymes, both forms of porcine or bovine heart enzyme were microinjected into the cytoplasm of mouse NIH 3T3 cells after conjugation with fluorescein, rhodamine, or in unlabeled form. The nuclear/cytoplasmic fluorescence ratio (N/C) was analyzed in the presence of cAMP (in the case of unlabeled enzyme by antibodies). Under all circumstances, the N/C ratio obtained with the encoded Asn2 form was significantly higher than that with the deamidated, Asp2 form; i.e., the Asn2 form reached a larger nuclear concentration than the Asp2 form. Comparable data were obtained with a human cell line. The differential intracellular distribution of both enzyme forms is also reflected by functional data. It correlates with the degree of phosphorylation of the key serine in CREB family transcription factors in the nucleus. Microinjection of myristoylated recombinant bovine Cα and the Asn2 deletion mutant of it yielded N/C ratios in the same range as encoded native enzymes. Thus, Asn2 seems to serve as a potential site for modulating electronegativity. The data indicate that the NH2-terminal domain of the PKA C-subunit contributes to the intracellular distribution of free enzyme, which can be altered by site-specific in vivo deamidation. The model character for other signaling proteins starting with myrGly-Asn is discussed.

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Regulation of Cardiac L-Type Ca 2+ Channel Ca V 1.2 Via the β-Adrenergic-cAMP-Protein Kinase A Pathway

Circulation Research ◽

10.1161/circresaha.113.301781 ◽

2013 ◽

Vol 113 (5) ◽

pp. 617-631 ◽

Cited By ~ 59

Author(s):

Sharon Weiss ◽

Shimrit Oz ◽

Adva Benmocha ◽

Nathan Dascal

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Adrenergic Receptor ◽

Transgenic Animals ◽

Receptor Activation ◽

Model Systems ◽

Adrenergic Stimulation ◽

New Findings ◽

Kinase A

In the heart, adrenergic stimulation activates the β-adrenergic receptors coupled to the heterotrimeric stimulatory G s protein, followed by subsequent activation of adenylyl cyclase, elevation of cyclic AMP levels, and protein kinase A (PKA) activation. One of the main targets for PKA modulation is the cardiac L-type Ca 2+ channel (Ca V 1.2) located in the plasma membrane and along the T-tubules, which mediates Ca 2+ entry into cardiomyocytes. β-Adrenergic receptor activation increases the Ca 2+ current via Ca V 1.2 channels and is responsible for the positive ionotropic effect of adrenergic stimulation. Despite decades of research, the molecular mechanism underlying this modulation has not been fully resolved. On the contrary, initial reports of identification of key components in this modulation were later refuted using advanced model systems, especially transgenic animals. Some of the cardinal debated issues include details of specific subunits and residues in Ca V 1.2 phosphorylated by PKA, the nature, extent, and role of post-translational processing of Ca V 1.2, and the role of auxiliary proteins (such as A kinase anchoring proteins) involved in PKA regulation. In addition, the previously proposed crucial role of PKA in modulation of unstimulated Ca 2+ current in the absence of β-adrenergic receptor stimulation and in voltage-dependent facilitation of Ca V 1.2 remains uncertain. Full reconstitution of the β-adrenergic receptor signaling pathway in heterologous expression systems remains an unmet challenge. This review summarizes the past and new findings, the mechanisms proposed and later proven, rejected or disputed, and emphasizes the essential issues that remain unresolved.

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