Agents that affect cAMP levels or protein kinase A activity modulate memory consolidation when injected into rat hippocampus but not amygdala

Growth factor receptor tyrosine kinase regulation of the sequential phosphorylation reactions leading to mitogen-activated protein (MAP) kinase activation in PC12 cells has been investigated. In response to epidermal growth factor, nerve growth factor, and platelet-derived growth factor, B-Raf and Raf-1 are activated, phosphorylate recombinant kinase-inactive MEK-1, and activate wild-type MEK-1. MEK-1 is the dual-specificity protein kinase that selectively phosphorylates MAP kinase on tyrosine and threonine, resulting in MAP kinase activation. B-Raf and Raf-1 are growth factor-regulated Raf family members which regulate MEK-1 and MAP kinase activity in PC12 cells. Protein kinase A activation in response to elevated cyclic AMP (cAMP) levels inhibited B-Raf and Raf-1 stimulation in response to growth factors. Ras.GTP loading in response to epidermal growth factor, nerve growth factor, or platelet-derived growth factor was unaffected by protein kinase A activation. Even though elevated cAMP levels inhibited Raf activation, the growth factor activation of MEK-1 and MAP kinase was unaffected in PC12 cells. The results demonstrate that tyrosine kinase receptor activation of MEK-1 and MAP kinase in PC12 cells is regulated by B-Raf and Raf-1, whose activation is inhibited by protein kinase A, and MEK activators, whose activation is independent of cAMP regulation.

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B-Raf-dependent regulation of the MEK-1/mitogen-activated protein kinase pathway in PC12 cells and regulation by cyclic AMP.

Molecular and Cellular Biology ◽

10.1128/mcb.14.10.6522 ◽

1994 ◽

Vol 14 (10) ◽

pp. 6522-6530 ◽

Cited By ~ 128

Author(s):

R R Vaillancourt ◽

A M Gardner ◽

G L Johnson

Keyword(s):

Growth Factor ◽

Protein Kinase ◽

Map Kinase ◽

Protein Kinase A ◽

Pc12 Cells ◽

Kinase Activation ◽

Mitogen Activated Protein ◽

Epidermal Growth ◽

Camp Levels ◽

Kinase A

Growth factor receptor tyrosine kinase regulation of the sequential phosphorylation reactions leading to mitogen-activated protein (MAP) kinase activation in PC12 cells has been investigated. In response to epidermal growth factor, nerve growth factor, and platelet-derived growth factor, B-Raf and Raf-1 are activated, phosphorylate recombinant kinase-inactive MEK-1, and activate wild-type MEK-1. MEK-1 is the dual-specificity protein kinase that selectively phosphorylates MAP kinase on tyrosine and threonine, resulting in MAP kinase activation. B-Raf and Raf-1 are growth factor-regulated Raf family members which regulate MEK-1 and MAP kinase activity in PC12 cells. Protein kinase A activation in response to elevated cyclic AMP (cAMP) levels inhibited B-Raf and Raf-1 stimulation in response to growth factors. Ras.GTP loading in response to epidermal growth factor, nerve growth factor, or platelet-derived growth factor was unaffected by protein kinase A activation. Even though elevated cAMP levels inhibited Raf activation, the growth factor activation of MEK-1 and MAP kinase was unaffected in PC12 cells. The results demonstrate that tyrosine kinase receptor activation of MEK-1 and MAP kinase in PC12 cells is regulated by B-Raf and Raf-1, whose activation is inhibited by protein kinase A, and MEK activators, whose activation is independent of cAMP regulation.

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Pde1 Phosphodiesterase Modulates Cyclic AMP Levels through a Protein Kinase A-Mediated Negative Feedback Loop in Cryptococcus neoformans

Eukaryotic Cell ◽

10.1128/ec.4.12.1971-1981.2005 ◽

2005 ◽

Vol 4 (12) ◽

pp. 1971-1981 ◽

Cited By ~ 55

Author(s):

Julie K. Hicks ◽

Yong-Sun Bahn ◽

Joseph Heitman

Keyword(s):

Protein Kinase ◽

Cyclic Amp ◽

Protein Kinase A ◽

Cryptococcus Neoformans ◽

Mutant Strain ◽

Negative Feedback ◽

Feedback Loop ◽

Negative Feedback Loop ◽

Camp Levels ◽

Kinase A

ABSTRACT The virulence of the human pathogenic fungus Cryptococcus neoformans is regulated by a cyclic AMP (cAMP)-dependent protein kinase A (PKA) signaling cascade that promotes mating and the production of melanin and capsule. In this study, genes encoding homologs of the Saccharomyces cerevisiae low- and high-affinity phosphodiesterases, PDE1 and PDE2, respectively, were deleted in serotype A strains of C. neoformans. The resulting mutants exhibited moderately elevated levels of melanin and capsule production relative to the wild type. Epistasis experiments indicate that Pde1 functions downstream of the Gα subunit Gpa1, which initiates cAMP-dependent signaling in response to an extracellular signal. Previous work has shown that the PKA catalytic subunit Pka1 governs cAMP levels via a negative feedback loop. Here we show that a pde1Δ pka1Δ mutant strain exhibits cAMP levels that are dramatically increased (∼15-fold) relative to those in a pka1Δ single mutant strain and that a site-directed mutation in a consensus PKA phosphorylation site reduces Pde1 function. These data provide evidence that fluctuations in cAMP levels are modulated by both Pka1-dependent regulation of Pde1 and another target that comprise a robust negative feedback loop to tightly constrain intracellular cAMP levels.

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NO releases bombesin-like immunoreactivity from enteric synaptosomes by cross-activation of protein kinase A

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1999.276.6.g1521 ◽

1999 ◽

Vol 276 (6) ◽

pp. G1521-G1530 ◽

Cited By ~ 1

Author(s):

M. Kurjak ◽

R. Fritsch ◽

D. Saur ◽

V. Schusdziarra ◽

H. D. Allescher

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Dependent Protein Kinase ◽

No Donor ◽

Camp Dependent Protein Kinase ◽

Dependent Protein ◽

Camp Levels ◽

No Releases ◽

Kinase A

The effect of nitric oxide (NO) on the release of bombesin-like immunoreactivity (BLI) was examined in synaptosomes of rat small intestine. The NO donor S-nitroso- N-acetylpenicillamine (SNAP; 10−7 to 10−4 M) significantly stimulated BLI release. In the presence of the NO scavenger oxyhemoglobin (10−3 M) or the guanylate cyclase inhibitor ODQ (10−5 M), SNAP-induced BLI release was antagonized. In addition, SNAP increased the synaptosomal cGMP content and elevation of cGMP levels by zaprinast (3 × 10−5 M), an inhibitor of the cGMP-specific phosphodiesterase (PDE) type 5, and increased basal and SNAP-induced BLI release. NO-induced BLI release was blocked by Rp-adenosine 3′,5′-cyclic monophosphorothioate (3 × 10−5 M and 10−4 M), an inhibitor of the cAMP-dependent protein kinase A, whereas KT-5823 (3 × 10−6 M) and Rp-8-(4-chlorophenylthio)-cGMP (5 × 10−5M), inhibitors of the cGMP-dependent protein kinase G, had no effect. Because cGMP inhibits the cAMP-specific PDE3, thereby increasing cAMP levels, the role of PDE3 was investigated. Trequinsin (10−8 M), a specific blocker of PDE3, stimulated basal BLI release but had no additive effect on NO-induced release, suggesting a similar mechanism of action. These data demonstrate that because of a cross-activation of cAMP-dependent protein kinase A by endogenous cGMP BLI can be released by NO from enteric synaptosomes.

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Overexpression of Dd PK2 protein kinase causes rapid development and affects the intracellular cAMP pathway of Dictyostelium discoideum

Development ◽

10.1242/dev.115.3.785 ◽

1992 ◽

Vol 115 (3) ◽

pp. 785-790 ◽

Cited By ~ 13

Author(s):

C. Anjard ◽

S. Pinaud ◽

R.R. Kay ◽

C.D. Reymond

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Rapid Development ◽

Physiological Role ◽

Intracellular Camp ◽

Developmentally Regulated ◽

K Cells ◽

Frame Shift ◽

Camp Levels ◽

Kinase A

The Dd PK2 gene codes for a putative protein of 648 amino acids with a C-terminal half sharing high homology with protein kinase A catalytic subunits from other organisms. In order to find out more about the physiological role of the Dd PK2 kinase, its gene, and a version having a frame shift mutation in the middle of the catalytic region, were overexpressed in developing Dictyostelium cells. Both the intact gene (K-) and the frame shift mutant (Kdel-) caused rapid development with spores formed in 16–18 hours compared to the 24 hours required by their parent. This result was confirmed by the pattern of expression of some developmentally regulated genes. Other rapid developing strains (rde) are activated in the cAMP second messenger system. Both K- and Kdel-containing strains have lower cAMP levels than the parental strain during late development, thus resembling rdeC mutants. K-cells (but not Kdel-cells) produced bizarre fruiting bodies with many prostrate forms. The parallel with rde mutants was confirmed by demonstrating that K-cells are able to form spores in submerged monolayer culture. Furthermore, K-cells have about four times more protein kinase A (cAPK) activity than wild-type cells. These results indicate that the N-terminal domain of Dd PK2 is sufficient to influence cAMP levels and to provoke rapid development, whereas kinase activity seems to be required for the sporogenous phenotype. The association between elevated cAPK and Dd PK2 overexpression phenotype further indicates a role for cAPK in the formation of spores.

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