Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.12 (PKG)
 2,515 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphorylation of the cAMP response element binding protein (CREB) by the catalytic subunit of cAMP-dependent protein kinase (cAK) has been implicated in the cAMP-dependent stimulation of gene transcription. delta-CREB, a spliced variant of CREB, and CREBtide (KRREILSRRPSYR), a synthetic peptide based on the phosphorylation sequence in delta-CREB, were tested as substrates of cAK. Phosphorylation of delta-CREB (0.17 microM) was stoichiometric within 30 s when using a concentration of cAK which approximated the intracellular level (0.2 microM). The rate of phosphorylation of delta-CREB was comparable to the rates of the best physiological substrates of cAK tested. The rate of CREBtide phosphorylation was at least as great as that of delta-CREB, indicating that the peptide retained the determinants of delta-CREB which were responsible for substrate efficacy. The apparent Km of CREBtide phosphorylation by cAK was 3.9 microM, which is 10-fold lower than that of kemptide (Km = 39 microM), the synthetic peptide substrate most often employed for cAK measurement. The Vmax values were 12.4 mumol/(min.mg) for CREBtide and 9.8 mumol/(min.mg) for kemptide. The apparent Km of CREBtide phosphorylation by cGMP-dependent protein kinase (cGK) was 2.9 microM and the Vmax value was 3.2 mumol/(min.mg). Both delta-CREB and CREBtide were phosphorylated at a much slower rate by cGK as compared with cAK, implying that the high cAK/cGK specificity exhibited by delta-CREB was retained by the peptide. Taken together, the results indicated that delta-CREB and CREBtide are among the best substrates tested for cAK and suggested that phosphorylation of CREB by this enzyme could occur in intact cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:cAMP-dependent protein kinase, but not the cGMP-dependent enzyme, rapidly phosphorylates delta-CREB, and a synthetic delta-CREB peptide. 133 14

We have evaluated the importance of the Ser/Thr protein phosphorylation and dephosphorylation for chondrogenesis in high-density chicken limb bud mesenchymal cell cultures (HDCs) by using H89, a cell-permeable protein kinase inhibitor, and okadaic acid (OA), a phosphoprotein phosphatase (PP)-specific inhibitor molecule. When 20 nM OA was applied to the HDCs on Days 2 and 3 of culturing, it significantly inhibited protein phosphatase 2A (PP2A), enhanced cartilage formation, and elevated the activity of cAMP-dependent protein kinase (PKA). Application of 20 microM H89 significantly decreased the activity of PKA and blocked the chondrogenesis in HDCs. Furthermore, OA enhanced cartilage formation and elevated the suppressed activity of PKA even in the H89-pretreated HDCs. cGMP-dependent protein kinase was not detected in HDCs, while protein kinase Cmu (PKCmu), which is also inhibited by nanomolar concentrations of H89, was present throughout the culturing period. Neither OA nor H89 influenced the expression of the catalytic subunit of PKA or the cAMP response element binding protein, CREB. However, a significantly elevated amount of Ser-133-phosphorylated-CREB (P-CREB) was detected following addition of OA, while H89 treatment resulted in a decrease of the amount of P-CREB. Our results demonstrate that PP2A plays a role in the regulation of the PKA signaling pathway and that the phosphorylation level of CREB is influenced by the activity of both enzymes during in vitro chondrogenesis.
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PMID:Protein phosphatase 2A is involved in the regulation of protein kinase A signaling pathway during in vitro chondrogenesis. 1192

The transcription factor NF-kappaB is activated in cellular stress responses. This requires rapid regulation of its function, which is accomplished, in part, by various modes of phosphorylation. Even though diverse DNA binding subunits of NF-kappaB proteins may transactivate from distinct recognition sequences, the differential regulation of transcription from the large number of NF-kappaB responsive sites in various gene promoters and enhancers has been incompletely understood. The cyclic GMP-dependent kinase (PKG) is an important mediator of signal transduction that may induce gene expression through cAMP response element binding protein (CREB) and through other, yet undefined, mechanisms. We have previously characterized a signal transduction pathway that leads to activation-induced cell death in T-lymphocytes and involves the activation of PKG. Here we demonstrate that the NF-kappaB proteins p65, p49 (also called p52), and p50 are specific substrates for this kinase. PKG dose-dependently increases the transactivating activity of p65 from the NF-kappaB consensus sequence. It also mediates dose-dependently an increase in transcriptional activity by p49 or p50 from a unique CCAAT/enhance binding protein (C/EBP)-associated NF-kappaB site, but not from the consensus site. Phosphorylation of p65, p50, or p49 does not alter their subcellular distribution. Because the release of cytosolic p65/p50 heterodimers into the nucleus is by itself insufficient to differentiate all the numerous NF-kappaB promoter sequences, phosphorylation of the DNA-binding subunits reveals a form of differential regulation of NF-kappaB activity and it implies a novel pathway for PKG-induced gene transcription. These observations may bear on mechanisms of programmed cell death in T-lymphocytes. They may also be relevant to ongoing efforts to induce cancer cell apoptosis through activation of PKG.
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PMID:Phosphorylation of NF-kappaB proteins by cyclic GMP-dependent kinase. A noncanonical pathway to NF-kappaB activation. 1275 37

Nitric oxide (NO) is known to affect synaptic plasticity in various regions of the brain via the cGMP-cGMP-dependent protein kinase (PKG) pathway. We found that a novel compound 3-(5-hydroxymethyl-2-furyl)-1-benzyl-indazole (YC-1), a drug known to modulate the response of soluble guanylyl cyclase to NO, greatly potentiates long-term potentiation (LTP). This compound markedly enhanced the induction of LTP in rat hippocampal and amygdala slices by weak tetanic stimulation. The potentiation of LTP by YC-1 was greatly reduced by NO synthase inhibitor Ng-nitro-l-arginine-methylester, guanylyl cyclase inhibitor 1 H-[1,2,4]-oxadiazolo(4,3-a)-quinoxalin-1-one, and PKG inhibitor (9S,10R,12R)-2,3,9,10,11,12, hexahydro-10-methoxy-2,9-dimethyl-1-ox0-9.12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-I][1,6]benzodiazocine-10-carboxylic acid methyl ester (KT5823). In addition, mitogen-activated protein kinase kinase inhibitor 2'-amino-3'-methoxyflavone (PD98059) also markedly inhibited LTP potentiating action of YC-1. Intracellular increase of Ca2+ concentration derived from N-methyl-d-aspartate and glutamate metabotropic receptors contributes to the potentiating action of YC-1. Concurrent perfusion of YC-1 and NO donor sodium nitroprusside for a short time period resulted in the induction of LTP by stimuli at a frequency as low as 0.02 Hz. Incubation of unstimulated hippocampal slices with YC-1 plus nitroprusside increased the immunofluorescence of phospho-extracellular signal-regulated kinase (ERK) and phospho-cAMP response element binding protein (CREB). Furthermore, the Western blot shows that the phosphorylation of ERKs 1 and 2 and CREB of unstimulated hippocampal slices was increased by YC-1 plus nitroprusside, which was inhibited by KT5823. The NO-cGMP-PKG-ERK signaling pathway thus plays important role in the potentiation of LTP by YC-1.
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PMID:Enhancement of long-term potentiation by a potent nitric oxide-guanylyl cyclase activator, 3-(5-hydroxymethyl-2-furyl)-1-benzyl-indazole. 1276 28

It is known that the nitric oxide (NO)/cGMP pathway affects neuronal development and the expression of the different proteins is developmentally dependent in several brain areas. However, so far there are no data on the expression of the proteins involved in this signalling system during the development of the cerebellar granule cell, one of the most widely used models of neuronal development. This study was accordingly designed to analyse the developmental regulation of neuronal nitric oxide synthase (nNOS), soluble guanylyl cyclase subunits (alpha1, alpha2 and beta1) and cGMP-dependent protein kinases (cGK I and cGK II) in cerebellar granule cells through real time-polymerase chain reaction (RT-PCR) and Western blotting. We were able to detect guanylyl cyclase subunits and cGK I and cGK II in cerebellar granule cells at every stage of development examined (cells freshly isolated from 7-day-old rat pups, and cells cultured for 7 days or 14 days). Expression levels, nevertheless, varied significantly at each stage. nNOS, alpha2 and beta1 and cGK II levels increased during granule cell development, while alpha1 and cGK I showed an opposite behaviour pattern; the levels of these latter proteins diminished as the cells matured. The functionality of this pathway was assessed by stimulating cells kept in culture for 7 days with DEA/NO or with N-methyl-D-aspartate (NMDA). Cells responded by increasing intracellular cGMP and activating cGMP-dependent protein kinase activity, which effectively phosphorylated two well-known substrates of this activity, the vasodilator stimulated phosphoprotein (VASP) and the cAMP response element binding protein (CREB). In summary, through both functional and biochemical tests, this is the first demonstration of a complete NO/cGMP signalling transduction pathway in cerebellar granule cells. Our results also indicate the developmental regulation of the proteins in this system.
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PMID:Elements of the nitric oxide/cGMP pathway expressed in cerebellar granule cells: biochemical and functional characterisation. 1531 77

Although it is well established that cyclic adenosine monophosphate (cAMP) signalling via cAMP-dependent protein kinase (PKA)within neurons plays an important role in depression and antidepressant treatment, the importance of several newly discovered targets that function independently from PKA, such as exchange protein activated by cAMP (Epac), remains unexplored in this regard. In this study we used a cAMP analogue that inhibits PKA but not Epac (Rp-8-Br-cAMP), to explore the modifying actions of these two targets on immobility in the forced swim test (FST) and cerebellar cAMP response element binding protein (CREB) phosphorylation in rats. In addition, we assessed central cAMP and cGMP levels and investigated the involvement of cGMP-dependent protein kinase (PKG) on any observed effects by using a selective PKG inhibitor (Rp-8-Br-PET-cGMPS).Interestingly, Rp-8-Br-cAMPS strongly reduced immobility in the FST and induced an increase in the phosphorylation of CREB in the cerebellum, effects that were unaltered by the co-administration of Rp-8-Br-PET-cGMPS. Furthermore, Rp-8-Br-cAMPS increased the accumulation of cAMP and cGMP in the hippocampus, frontal cortex and cerebellum of these rats. Together, these results suggest that in addition to activating PKA, elevated cAMP may also stimulate other targets that mediate antidepressant activity. According to the pharmacodynamic profile of Rp-8-Br-cAMPS and taking into consideration what has recently been discovered regarding the cAMP signalling system, a likely candidate is the guanine nucleotide exchange factor, Epac.
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PMID:An inhibitor of cAMP-dependent protein kinase induces behavioural and neurological antidepressant-like effects in rats. 2159 96