Project description:The second messenger cAMP acts via protein kinase A (PKA) to induce apoptosis by mechanisms that are poorly understood. Here, we assessed a role for mitochondria and analyzed gene expression in cAMP/PKA-promoted apoptosis by comparing wild-type (WT) S49 lymphoma cells and the S49 variant, D- (cAMP-deathless), which lacks cAMP-promoted apoptosis but has wild-type levels of PKA activity and cAMP-promoted G1 growth arrest. Treatment of WT, but not D-, S49 cells with 8-CPT-cAMP for 24 h induced loss of mitochondrial membrane potential, mitochondrial release of cytochrome c and Smac and increase in caspase-3 activity. Gene expression analysis (using Affymetrix 430 2.0 Arrays) revealed that WT and D- cells incubated with 8-CPT-cAMP have similar, but non-identical, extents of cAMP-regulated gene expression at 2h (~800 transcripts) and 6h (~1000 transcripts) (|Fold|>2, P<0.06); by contrast, at 24h ~2500 and ~1100 transcripts were changed in WT and D- cells, respectively. Using an approach that combined regression analysis, clustering and functional annotation to identify transcripts that showed differential expression between WT and D- cells, we found differences in cAMP-mediated regulation of mRNAs involved in transcriptional repression, apoptosis, the cell cycle, RNA splicing, Golgi and lysosomes. The 2 cell lines differed in CREB phosphorylation and expression of the transcriptional inhibitor Icer and in cAMP-regulated expression of genes in the Inhibitor of apoptosis (IAP) and Bcl families. The findings indicate that cAMP/PKA-promoted apoptosis of lymphoid cells occurs via mitochondrial-mediated events and imply that such apoptosis involves gene networks in multiple biochemical pathways. Experiment Overall Design: S49 D- cells were treated with 8-CPT-cAMP over the course of 24 hours. Cells were prepared for hybridization to microarrays at times 0-untreated, 2h, 6h, and 24h after treatment with 8-CPT-cAMP. Experimental replicates were as follows n=4 for time 0 and n=3 for 2, 6, and 24h post treatment.
Project description:The second messenger cAMP acts via protein kinase A (PKA) to induce apoptosis by mechanisms that are poorly understood. Here, we assessed a role for mitochondria and analyzed gene expression in cAMP/PKA-promoted apoptosis by comparing wild-type (WT) S49 lymphoma cells and the S49 variant, D- (cAMP-deathless), which lacks cAMP-promoted apoptosis but has wild-type levels of PKA activity and cAMP-promoted G1 growth arrest. Treatment of WT, but not D-, S49 cells with 8-CPT-cAMP for 24 h induced loss of mitochondrial membrane potential, mitochondrial release of cytochrome c and Smac and increase in caspase-3 activity. Gene expression analysis (using Affymetrix 430 2.0 Arrays) revealed that WT and D- cells incubated with 8-CPT-cAMP have similar, but non-identical, extents of cAMP-regulated gene expression at 2h (~800 transcripts) and 6h (~1000 transcripts) (|Fold|>2, P<0.06); by contrast, at 24h ~2500 and ~1100 transcripts were changed in WT and D- cells, respectively. Using an approach that combined regression analysis, clustering and functional annotation to identify transcripts that showed differential expression between WT and D- cells, we found differences in cAMP-mediated regulation of mRNAs involved in transcriptional repression, apoptosis, the cell cycle, RNA splicing, Golgi and lysosomes. The 2 cell lines differed in CREB phosphorylation and expression of the transcriptional inhibitor Icer and in cAMP-regulated expression of genes in the Inhibitor of apoptosis (IAP) and Bcl families. The findings indicate that cAMP/PKA-promoted apoptosis of lymphoid cells occurs via mitochondrial-mediated events and imply that such apoptosis involves gene networks in multiple biochemical pathways. Keywords: time course
Project description:Signal transduction plays a crucial role in defending against external environmental challenges, which can modulate the cellular response to external stimuli. cAMP/PKA signaling pathway is one of the most important signaling circuits and is evolutionarily conserved in eukaryotes. A. oligospora is a typical nematode-trapping fungi that can specialize adhesive network traps to kill nematodes after sensing the signals. To elucidate the biological roles of cAMP-PKA signaling pathway, we characterized an adenylate cyclase orthologous protein, AoAcy, a cAMP-dependent protein kinase regulator, AoPKaR, and two cAMP-dependent protein kinase catalytic subunits, AoPKaCs in A. oligospora. Furthermore, phenotypic analysis of the gene disruption strains showed that the deletion of AoAcy resulted in a significant decrease in the content of cAMP and arthrobotrisins, and the results indicated that AoAcy, AoPKaR and AoPKaC1 were involved in the hyphae growth, trap morphogenesis, sporulation, stress resistance and autophagy. In addition, AoAcy and AoPKaC1 were also participated in the regulation of mitochondria, thereby affecting energy metabolism. While AoPKaC2 only affected sporulation, the number of nuclei and autophagy. Collectively, these findings highlight the essential role of cAMP/PKA signaling pathway in A. oligospora and provide insights into the regulation mechanisms of signaling pathways in trap formation and sporulation.
Project description:Initiation of adipocyte differentiation is promoted by the synergistic action of insulin/insulin-like growth factor, glucocorticoids, and agents activating cAMP-dependent signaling. The action of cAMP is mediated via PKA and Epac, where at least part of the PKA function relates to strong repression of Rho kinase activity, whereas Epac counteracts the reduction in insulin/insulin-like growth factor signaling associated with complete repression of Rho kinase activity. However, detailed knowledge of the Epac-dependent branch and the interplay with PKA is still limited. In the present study, we present a comprehensive evaluation of Epac-mediated processes and their interplay with PKA during the initiation of 3T3-L1 preadipocyte differentiation using a combination of proteomics, molecular approaches and bioinformatics. Proteomic analyses revealed 7 proteins specifically regulated in response to Epac activation, 4 in response to PKA activation, and 11 in response to the combined activation by Epac and PKA during the initial phase of differentiation. Network analyses indicated that the identified proteins are involved in pathways of importance for glucose metabolism, inositol metabolism and calcium-dependent signaling thereby adding a novel facet to our understanding of cAMP-mediated potentiation of adipocyte differentiation.
Project description:Nair2015 - Interaction between
neuromodulators via GPCRs - Effect on cAMP/PKA signaling (D2
Neuron)
This model is described in the article:
Sensing Positive versus
Negative Reward Signals through Adenylyl Cyclase-Coupled GPCRs
in Direct and Indirect Pathway Striatal Medium Spiny
Neurons.
Nair AG, Gutierrez-Arenas O,
Eriksson O, Vincent P, Hellgren Kotaleski J.
J. Neurosci. 2015 Oct; 35(41):
14017-14030
Abstract:
Transient changes in striatal dopamine (DA) concentration
are considered to encode a reward prediction error (RPE) in
reinforcement learning tasks. Often, a phasic DA change occurs
concomitantly with a dip in striatal acetylcholine (ACh),
whereas other neuromodulators, such as adenosine (Adn), change
slowly. There are abundant adenylyl cyclase (AC) coupled GPCRs
for these neuromodulators in striatal medium spiny neurons
(MSNs), which play important roles in plasticity. However,
little is known about the interaction between these
neuromodulators via GPCRs. The interaction between these
transient neuromodulator changes and the effect on cAMP/PKA
signaling via Golf- and Gi/o-coupled GPCR are studied here
using quantitative kinetic modeling. The simulations suggest
that, under basal conditions, cAMP/PKA signaling could be
significantly inhibited in D1R+ MSNs via ACh/M4R/Gi/o and an
ACh dip is required to gate a subset of D1R/Golf-dependent PKA
activation. Furthermore, the interaction between ACh dip and DA
peak, via D1R and M4R, is synergistic. In a similar fashion,
PKA signaling in D2+ MSNs is under basal inhibition via
D2R/Gi/o and a DA dip leads to a PKA increase by disinhibiting
A2aR/Golf, but D2+ MSNs could also respond to the DA peak via
other intracellular pathways. This study highlights the
similarity between the two types of MSNs in terms of high basal
AC inhibition by Gi/o and the importance of interactions
between Gi/o and Golf signaling, but at the same time predicts
differences between them with regard to the sign of RPE
responsible for PKA activation.Dopamine transients are
considered to carry reward-related signal in reinforcement
learning. An increase in dopamine concentration is associated
with an unexpected reward or salient stimuli, whereas a
decrease is produced by omission of an expected reward. Often
dopamine transients are accompanied by other neuromodulatory
signals, such as acetylcholine and adenosine. We highlight the
importance of interaction between acetylcholine, dopamine, and
adenosine signals via adenylyl-cyclase coupled GPCRs in shaping
the dopamine-dependent cAMP/PKA signaling in striatal neurons.
Specifically, a dopamine peak and an acetylcholine dip must
interact, via D1 and M4 receptor, and a dopamine dip must
interact with adenosine tone, via D2 and A2a receptor, in
direct and indirect pathway neurons, respectively, to have any
significant downstream PKA activation.
This model is hosted on
BioModels Database
and identified by:
BIOMD0000000636.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
Project description:Nair2015 - Interaction between
neuromodulators via GPCRs - Effect on cAMP/PKA signaling (D1
Neuron)
This model is described in the article:
Sensing Positive versus
Negative Reward Signals through Adenylyl Cyclase-Coupled GPCRs
in Direct and Indirect Pathway Striatal Medium Spiny
Neurons.
Nair AG, Gutierrez-Arenas O,
Eriksson O, Vincent P, Hellgren Kotaleski J.
J. Neurosci. 2015 Oct; 35(41):
14017-14030
Abstract:
Transient changes in striatal dopamine (DA) concentration
are considered to encode a reward prediction error (RPE) in
reinforcement learning tasks. Often, a phasic DA change occurs
concomitantly with a dip in striatal acetylcholine (ACh),
whereas other neuromodulators, such as adenosine (Adn), change
slowly. There are abundant adenylyl cyclase (AC) coupled GPCRs
for these neuromodulators in striatal medium spiny neurons
(MSNs), which play important roles in plasticity. However,
little is known about the interaction between these
neuromodulators via GPCRs. The interaction between these
transient neuromodulator changes and the effect on cAMP/PKA
signaling via Golf- and Gi/o-coupled GPCR are studied here
using quantitative kinetic modeling. The simulations suggest
that, under basal conditions, cAMP/PKA signaling could be
significantly inhibited in D1R+ MSNs via ACh/M4R/Gi/o and an
ACh dip is required to gate a subset of D1R/Golf-dependent PKA
activation. Furthermore, the interaction between ACh dip and DA
peak, via D1R and M4R, is synergistic. In a similar fashion,
PKA signaling in D2+ MSNs is under basal inhibition via
D2R/Gi/o and a DA dip leads to a PKA increase by disinhibiting
A2aR/Golf, but D2+ MSNs could also respond to the DA peak via
other intracellular pathways. This study highlights the
similarity between the two types of MSNs in terms of high basal
AC inhibition by Gi/o and the importance of interactions
between Gi/o and Golf signaling, but at the same time predicts
differences between them with regard to the sign of RPE
responsible for PKA activation.Dopamine transients are
considered to carry reward-related signal in reinforcement
learning. An increase in dopamine concentration is associated
with an unexpected reward or salient stimuli, whereas a
decrease is produced by omission of an expected reward. Often
dopamine transients are accompanied by other neuromodulatory
signals, such as acetylcholine and adenosine. We highlight the
importance of interaction between acetylcholine, dopamine, and
adenosine signals via adenylyl-cyclase coupled GPCRs in shaping
the dopamine-dependent cAMP/PKA signaling in striatal neurons.
Specifically, a dopamine peak and an acetylcholine dip must
interact, via D1 and M4 receptor, and a dopamine dip must
interact with adenosine tone, via D2 and A2a receptor, in
direct and indirect pathway neurons, respectively, to have any
significant downstream PKA activation.
This model is hosted on
BioModels Database
and identified by:
BIOMD0000000635.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
Project description:Specific functions for different cyclic nucleotide phosphodiesterases (PDEs) have not yet been identified in most cell types. Conventional approaches to study PDE function typically rely on global cAMP measurements, general increases in cAMP- dependent protein kinase (PKA) activity, or activity of exchange protein activated by cAMP (EPAC). Although newer approaches utilizing subcellularly-targeted FRET reporter sensors have helped to define more compartmentalized regulation of cAMP, PKA, and EPAC, they have limited ability to link this regulation to downstream effector molecules and biological functions. To address this problem, we have begun to use an unbiased, mass spectrometry-based approach coupled with treatment using PDE isozyme-selective inhibitors to characterize the phosphoproteome of the "functional pools" of cAMP/PKA/EPAC that are regulated by specific cAMP-PDEs (the PDE-regulated phosphoproteomes).
Project description:Intrinsic abnormalities in transplanted eutopic endometrium are believed to contribute to the pathogenesis of pelvic endometriosis. Herein, we investigated transcriptomic differences in human endometrial stromal fibroblasts (hESF) from women with (hESFendo) versus without (hESFnon-endo) endometriosis, in response to activation of the PKA pathway with 8-Br-cAMP. hESFnon-endo (n=4) and hESFendo (mild endometriosis, n=4) were isolated from eutopic endometrium and treated +/- 0.5mM 8-Br-cAMP for 96 hours. Purified total RNA was subjected to microarray analysis using the whole genome Gene 1.0 ST Affymetrix platform. 733 genes were regulated in cAMP-treated hESFnon-endo versus 172 genes in hESFendo, suggesting a blunted response to cAMP/PKA pathway activation in women with disease. Real-time PCR and ELISA validated the decreased expression of decidualization markers in hESFendo compared to hESFnon-endo. In the absence of disease, 8-Br-cAMP down-regulated progression through the cell-cycle due to a decrease in Cyclin D1, cyclin-dependent kinase 6 and cell division cycle 2, and an increase in cyclin-dependent kinase inhibitor 1A. However, cell cycle components in hESFendo were not responsive to 8-Br-cAMP, resulting in persistence of a proliferative phenotype. hESFendo treated with 8-Br-cAMP exhibited altered expression of immune response, extracellular matrix, cytoskeleton, and apoptosis genes. Changes in phosphodiesterase expression and activity were not different among experimental groups. Thus, eutopic hESF with increased proliferative potential may seed the pelvic cavity via retrograde menstruation and promote establishment, survival, and proliferation of endometriosis lesions, independent of hydrolysis of cAMP and likely due to an inherent abnormality in the PKA pathway in the presence of disease.
Project description:Light controls control a vast array of biological processes, including cell and organelle motility, stress responses, organismal development and the entrainment of circadian rhythms, that maintain diurnal cycles of activity in organisms from cyanobacteria to humans. Recent studies indicate that a type of antioxidant and signaling proteins, peroxiredoxins, sustain circadian rhythms independent of characterized circadian pacemakers in organisms from all the three kingdoms of life, suggesting a role for H2O2 production in circadian clocks. Whereas many circadian clocks involve photosensitive pigments such as melanopsin and cryptochromes it is unclear whether peroxiredoxins can respond to light stimuli and how they interact with global signaling networks regulating e.g. clocks and aging, such as cyclic AMP (cAMP)/protein kinase A (PKA). In yeast, that lacks decidated photoreceptors, blue light induces cAMP-PKA-dependent, nuclear accumulation of a transcription factor, Msn2. However, the mechanism by which light represses pathway activity to stimulate Msn2 nuclear translocation is unknown. Here we identify increased H2O2–production via a conserved peroxisomal oxidase as the cause of light-induced Msn2 nuclear concentration. The H2O2 signal is transduced by the catalytic cysteines of the peroxiredoxin Tsa1 that relieve Msn2 from inhibitory PKA phosphorylation causing its nuclear accumulation. We propose that yeast senses light via H2O2 and a peroxiredoxin to inhibit cAMP/PKA activity and our data form a framework for the study of light responses in cells lacking dedicated light receptors and cAMP-controlled biological rhythms in multicellular organisms.
Project description:Osteogenic differentiation of human mesenchymal stromal cells (hMSCs) may potentially be used in cell-based bone tissue-engineering applications to enhance the bone-forming potential of these cells. Osteogenic differentiation and adipogenic differentiation are thought to be mutually exclusive, and although several signaling pathways and cues that induce osteogenic or adipogenic differentiation, respectively, have been identified, there is no general consensus on how to optimally differentiate hMSCs into the osteogenic lineage. Some pathways have also been reported to be involved in both adipogenic and osteogenic differentiation, as for example, the protein kinase A (PKA) pathway, and the aim of this study was to investigate the role of cAMP/PKA signaling in differentiation of hMSCs in more detail. We show that activation of this pathway with dibutyryl-cAMP results in enhanced alkaline phosphatase expression, whereas another cAMP analog induces adipogenesis in long-term mineralization cultures. Adipogenic differentiation, induced by 8-bromo-cAMP, was accompanied by stronger PKA activity and higher expression of cAMP-responsive genes, suggesting that stronger activation correlates with adipogenic differentiation. In addition, a whole-genome expression analysis showed an increase in expression of adipogenic genes in 8-br-cAMP-treated cells. Furthermore, by means of quantitative polymerase chain reaction, we show differences in peroxisome proliferator-activated receptor-gamma activation, either alone or in combination with dexamethasone, thus demonstrating differential effects of the PKA pathway, most likely depending on its mode of activation.