Project description:Although a substantial number of hormones and drugs increase cellular cAMP levels, the global impact of cAMP and its major effector mechanism, protein kinase A (PKA), on gene expression is not known. Here we show that treatment of wild-type S49 lymphoma cells for 24 h with 8-(4-chlorophenylthio)-cAMP (CPT-cAMP), a PKA-selective cAMP analog, alters the expression of ~4500 of ~13,600 unique genes. By contrast, gene expression was unaltered in Kin- S49 cells (that lack PKA) incubated with CPT-cAMP. Changes in mRNA and protein expression of several cell-cycle regulators accompanied cAMP-induced G1-phase cell-cycle arrest of wild-type S49 cells. Within 2 h, CPT-cAMP altered expression of 152 genes that contain evolutionarily conserved cAMP-response elements (CRE) within 5 kb of transcriptional start sites, including the circadian clock gene Per1. Thus, cAMP through its activation of PKA produces extensive transcriptional regulation in eukaryotic cells. These transcriptional networks include a primary group of CRE-containing genes and secondary networks that include the circadian clock.
Project description:Abstract Although a substantial number of hormones and drugs increase cellular cAMP levels, the global impact of cAMP and its major effector mechanism, protein kinase A (PKA), on gene expression is not known. Here we show that treatment of wild-type S49 lymphoma cells for 24 h with 8-(4-chlorophenylthio)-cAMP (CPT-cAMP), a PKA-selective cAMP analog, alters the expression of ~4500 of ~13,600 unique genes. By contrast, gene expression was unaltered in Kin– S49 cells (that lack PKA) incubated with CPT-cAMP. Changes in mRNA and protein expression of several cell-cycle regulators accompanied cAMP-induced G1-phase cell-cycle arrest of wild-type S49 cells. Within 2 h, CPT-cAMP altered expression of 152 genes that contain evolutionarily conserved cAMP-response elements (CRE) within 5 kb of transcriptional start sites, including the circadian clock gene Per1. Thus, cAMP through its activation of PKA produces extensive transcriptional regulation in eukaryotic cells. These transcriptional networks include a primary group of CRE-containing genes and secondary networks that include the circadian clock. Keywords: time-course
Project description:Regulation of neurons by circadian clock genes is thought to contribute to the maintenance of neuronal functions that ultimately underlie animal behavior. However, the impact of circadian genes on cellular and molecular mechanisms that influnce synaptic plasticity and cognitive function remain to be identified. Here, we show that conditional deletion of the circadian gene Timeless in the adult forebrain leads to an impairment in working and fear memory in mice. These cognitive phenotypes were accompanied with LTP attenuation of hippocampal Schaffer-collateral synapses. We discovered TIMELESS protein acts as a transcriptional factor regulating phosphodiesterase 4B (PDE4B) expression. Through Pde4b transcription, TIMELESS negatively regulates cAMP signaling to modulate AMPA receptor GluA1 function and fine-tune synaptic plasticity. Our data provide insights into the neuron-specific function of mammalian TIMELESS by defining a mechanism that regulates synaptic plasticity and cognitive function.
Project description:Yapo2017- cAMP/PKA signalling in D1 dopamine receptor expressing medium-spiny neurons
This model is described in the article:
Detection of phasic dopamine
by D1 and D2 striatal medium spiny neurons.
Yapo C, Nair AG, Clement L, Castro
LR, Hellgren Kotaleski J, Vincent P.
J. Physiol. (Lond.) 2017 Aug; :
Abstract:
The phasic release of dopamine in the striatum determines
various aspects of reward and action selection, but the
dynamics of dopamine effect on intracellular signalling remains
poorly understood. We used genetically-encoded FRET biosensors
in striatal brain slices to quantify the effect of transient
dopamine on cAMP or PKA-dependent phosphorylation level, and
computational modelling to further explore the dynamics of this
signalling pathway. Medium-sized spiny neurons (MSNs), which
express either D1 or D2 dopamine receptors, responded to
dopamine by an increase or a decrease in cAMP, respectively.
Transient dopamine showed similar sub-micromolar efficacies on
cAMP in both D1 and D2 MSNs, thus challenging the commonly
accepted notion that dopamine efficacy is much higher on D2
than on D1 receptors. However, in D2 MSNs, the large decrease
in cAMP level triggered by transient dopamine did not translate
in a decrease in PKA-dependent phosphorylation level, owing to
the efficient inhibition of Protein Phosphatase 1 by DARPP-32.
Simulations further suggested that D2 MSNs can also operate in
a "tone-sensing" mode, allowing them to detect transient dips
in basal dopamine. Overall, our results show that D2 MSNs may
sense much more complex patterns of dopamine than previously
thought. This article is protected by copyright. All rights
reserved.
This model is hosted on
BioModels Database
and identified by:
MODEL1701170000.
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:Yapo2017 - A2AR/cAMP/PKA signalling in D2 dopamine receptor expressing medium-spiny neurons
This model is described in the article:
Detection of phasic dopamine
by D1 and D2 striatal medium spiny neurons.
Yapo C, Nair AG, Clement L, Castro
LR, Hellgren Kotaleski J, Vincent P.
J. Physiol. (Lond.) 2017 Aug; :
Abstract:
The phasic release of dopamine in the striatum determines
various aspects of reward and action selection, but the
dynamics of dopamine effect on intracellular signalling remains
poorly understood. We used genetically-encoded FRET biosensors
in striatal brain slices to quantify the effect of transient
dopamine on cAMP or PKA-dependent phosphorylation level, and
computational modelling to further explore the dynamics of this
signalling pathway. Medium-sized spiny neurons (MSNs), which
express either D1 or D2 dopamine receptors, responded to
dopamine by an increase or a decrease in cAMP, respectively.
Transient dopamine showed similar sub-micromolar efficacies on
cAMP in both D1 and D2 MSNs, thus challenging the commonly
accepted notion that dopamine efficacy is much higher on D2
than on D1 receptors. However, in D2 MSNs, the large decrease
in cAMP level triggered by transient dopamine did not translate
in a decrease in PKA-dependent phosphorylation level, owing to
the efficient inhibition of Protein Phosphatase 1 by DARPP-32.
Simulations further suggested that D2 MSNs can also operate in
a "tone-sensing" mode, allowing them to detect transient dips
in basal dopamine. Overall, our results show that D2 MSNs may
sense much more complex patterns of dopamine than previously
thought. This article is protected by copyright. All rights
reserved.
This model is hosted on
BioModels Database
and identified by:
MODEL1701170001.
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:Disrupted circadian activity is associated with many neuropsychiatric disorders. A major coordinator of circadian biological systems is adrenal glucocorticoid secretion which exhibits a pronounced pre-awakening peak that regulates metabolic, immune, and cardiovascular processes, as well as mood and cognitive function. Loss of this circadian rhythm during corticosteroid therapy is often associated with memory impairment. Surprisingly the mechanisms that underlie this deficit are not understood. In this study, in rats, we report that circadian regulation of the hippocampal transcriptome integrates crucial functional networks that link corticosteroid-inducible gene regulation to synaptic plasticity processes via an intra-hippocampal circadian transcriptional clock. Further, these circadian hippocampal functions were significantly impacted by corticosteroid treatment delivered in a five day oral dosing treatment protocol. Rhythmic expression of the hippocampal transcriptome, as well as the circadian regulation of synaptic plasticity were misaligned with the natural light/dark circadian entraining cues, resulting in memory impairment in hippocampal-dependent behavior. These findings provide mechanistic insights into how the transcriptional clock machinery within the hippocampus is influenced by corticosteroid exposure, leading to adverse effects on critical hippocampal functions, as well as identifying a molecular basis for memory deficits in patients treated with long-acting synthetic corticosteroids.
Project description:Disrupted circadian activity is associated with many neuropsychiatric disorders. A major coordinator of circadian biological systems is adrenal glucocorticoid secretion which exhibits a pronounced pre-awakening peak that regulates metabolic, immune, and cardiovascular processes, as well as mood and cognitive function. Loss of this circadian rhythm during corticosteroid therapy is often associated with memory impairment. Surprisingly the mechanisms that underlie this deficit are not understood. In this study, in rats, we report that circadian regulation of the hippocampal transcriptome integrates crucial functional networks that link corticosteroid-inducible gene regulation to synaptic plasticity processes via an intra-hippocampal circadian transcriptional clock. Further, these circadian hippocampal functions were significantly impacted by corticosteroid treatment delivered in a five day oral dosing treatment protocol. Rhythmic expression of the hippocampal transcriptome, as well as the circadian regulation of synaptic plasticity were misaligned with the natural light/dark circadian entraining cues, resulting in memory impairment in hippocampal-dependent behavior. These findings provide mechanistic insights into how the transcriptional clock machinery within the hippocampus is influenced by corticosteroid exposure, leading to adverse effects on critical hippocampal functions, as well as identifying a molecular basis for memory deficits in patients treated with long-acting synthetic corticosteroids.
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:The circadian system influences many different biological processes, including memory performance. While the suprachiasmatic nucleus (SCN) functions as the brain’s central pacemaker, downstream “satellite clocks” may also regulate local functions based on the time of day. Within the dorsal hippocampus (DH), for example, local molecular oscillations may contribute to time-of-day effects on memory. Here, we used the hippocampus-dependent Object Location Memory task to determine how memory is regulated across the day/night cycle in mice. First, we systematically determined which phase of memory (acquisition, consolidation, or retrieval) is modulated across the 24h day. We found that mice show better long-term memory performance during the day than at night, an effect that was specifically attributed to diurnal changes in memory consolidation, as neither memory acquisition nor memory retrieval fluctuated across the day/night cycle. Using RNA-sequencing we identified the circadian clock gene Period1 (Per1) as a key mechanism capable of supporting this diurnal fluctuation in memory consolidation, as Per1 oscillates in tandem with memory performance. We then show that local knockdown of Per1 within the DH has no effect on either the circadian rhythm or sleep behavior, although previous work has shown this manipulation impairs memory. Thus, Per1 may independently function within the DH to regulate memory in addition to its known role in regulating the circadian system within the SCN. Per1 may therefore exert local diurnal control over memory consolidation within the DH.
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.