Localized Effects of cAMP Mediated by Distinct Routes of Protein Kinase A

2004 ◽  
Vol 84 (1) ◽  
pp. 137-167 ◽  
Author(s):  
KJETIL TASKÉN ◽  
EINAR MARTIN AANDAHL
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Biological Effects ◽  
Organ Specificity ◽  
Complex Signal ◽  
Signal Pathways ◽  
Pka Pathway ◽  
Kinase A

Taskén, Kjetil, and Einar Martin Aandahl. Localized Effects of cAMP Mediated by Distinct Routes of Protein Kinase A. Physiol Rev 84: 137–167, 2004; 10.1152/physrev.00021.2003.—More than 20% of the human genome encodes proteins involved in transmembrane and intracellular signaling pathways. The cAMP-protein kinase A (PKA) pathway is one of the most common and versatile signal pathways in eukaryotic cells and is involved in regulation of cellular functions in almost all tissues in mammals. Various extracellular signals converge on this signal pathway through ligand binding to G protein-coupled receptors, and the cAMP-PKA pathway is therefore tightly regulated at several levels to maintain specificity in the multitude of signal inputs. Ligand-induced changes in cAMP concentration vary in duration, amplitude, and extension into the cell, and cAMP microdomains are shaped by adenylyl cyclases that form cAMP as well as phosphodiesterases that degrade cAMP. Different PKA isozymes with distinct biochemical properties and cell-specific expression contribute to cell and organ specificity. A kinase anchoring proteins (AKAPs) target PKA to specific substrates and distinct subcellular compartments providing spatial and temporal specificity for mediation of biological effects channeled through the cAMP-PKA pathway. AKAPs also serve as scaffolding proteins that assemble PKA together with signal terminators such as phosphatases and cAMP-specific phosphodiesterases as well as components of other signaling pathways into multiprotein signaling complexes that serve as crossroads for different paths of cell signaling. Targeting of PKA and integration of a wide repertoire of proteins involved in signal transduction into complex signal networks further increase the specificity required for the precise regulation of numerous cellular and physiological processes.

scholarly journals Specificity and spatial dynamics of protein kinase A signaling organized by A-kinase-anchoring proteins

2010 ◽  
Vol 44 (5) ◽  
pp. 271-284 ◽  
Author(s):  
Guillaume Pidoux ◽  
Kjetil Taskén
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Biological Effects ◽  
Spatial Dynamics ◽  
Signal Pathways ◽  
Post Translational Modification ◽  
Anchoring Proteins ◽  
High Level ◽  
Pka Pathway ◽  
Kinase A

Protein phosphorylation is the most common post-translational modification observed in cell signaling and is controlled by the balance between protein kinase and phosphatase activities. The cAMP–protein kinase A (PKA) pathway is one of the most studied and well-known signal pathways. To maintain a high level of specificity, the cAMP–PKA pathway is tightly regulated in space and time. A-kinase-anchoring proteins (AKAPs) target PKA to specific substrates and distinct subcellular compartments providing spatial and temporal specificity in the mediation of biological effects controlled by the cAMP–PKA pathway. AKAPs also serve as scaffolding proteins that assemble PKA together with signal terminators such as phosphoprotein phosphatases and cAMP-specific phosphodiesterases as well as components of other signaling pathways into multiprotein-signaling complexes.

scholarly journals Cooperative Activation of Lipolysis by Protein Kinase A and Protein Kinase C Pathways in 3T3-L1 Adipocytes

Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 4940-4947 ◽  
Author(s):  
Katrin Fricke ◽  
Aleksandra Heitland ◽  
Erik Maronde
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Hormone Sensitive Lipase ◽  
Glycerol Release ◽  
Kinase C ◽  
Lipolytic Effect ◽  
Pka Pathway ◽  
Kinase A

Abstract In the present study, we investigate the coherence of signaling pathways leading to lipolysis in 3T3-L1 adipocytes. We observe two linear signaling pathways: one well known, acting via cAMP and protein kinase A (PKA) activation, and a second one induced by phorbol 12-myristate 13-acetate treatment involving protein kinase C (PKC) and MAPK. We demonstrate that both the PKA regulatory subunits RIα and RIIβ are expressed in 3T3-L1 adipocytes and are responsible for the lipolytic effect mediated via the cAMP/PKA pathway. Inhibition of the PKA pathway by the selective PKA inhibitor Rp-8-CPT-cAMPS does not impair lipolysis induced by PKC activation, and neither PD98059 nor U0126, as known MAPK kinase inhibitors, changes the level of glycerol release caused by PKA activation, indicating no cross-talk between these two pathways when only one is activated. However, when both are activated, they act synergistically on glycerol release. Additional experiments focusing on this synergy show no involvement of MAPK phosphorylation and cAMP formation. Phosphorylation of hormone-sensitive lipase is similar upon stimulation of either pathway, but we demonstrate a difference in the ability of both PKA and the PKC pathway activation to phosphorylate perilipin, which in turn may be an explanation for the different maximal lipolytic effect of both pathways.

scholarly journals The activation of the chymotrypsin-like activity of the proteasome is regulated by soluble adenyl cyclase/cAMP/protein kinase A pathway and required for human sperm capacitation

2019 ◽  
Vol 25 (10) ◽  
pp. 587-600 ◽  
Author(s):  
Héctor Zapata-Carmona ◽  
Lina Barón ◽  
Lidia M Zuñiga ◽  
Emilce Silvina Díaz ◽  
Milene Kong ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Current Knowledge ◽  
Human Sperm ◽  
Adenyl Cyclase ◽  
Sperm Capacitation ◽  
Time Treatment ◽  
Proteasome Subunits ◽  
Pka Pathway ◽  
Kinase A

Abstract One of the first events of mammalian sperm capacitation is the activation of the soluble adenyl cyclase/cAMP/protein kinase A (SACY/cAMP/PKA) pathway. Here, we evaluated whether the increase in PKA activity at the onset of human sperm capacitation is responsible for the activation of the sperm proteasome and whether this activation is required for capacitation progress. Viable human sperm were incubated with inhibitors of the SACY/cAMP/PKA pathway. The chymotrypsin-like activity of the sperm proteasome was evaluated using a fluorogenic substrate. Sperm capacitation status was evaluated using the chlortetracycline assay and tyrosine phosphorylation. To determine whether proteasomal subunits were phosphorylated by PKA, the proteasome was immunoprecipitated and tested on a western blot using an antibody against phosphorylated PKA substrates. Immunofluorescence microscopy analysis and co-immunoprecipitation (IPP) were used to investigate an association between the catalytic subunit alpha of PKA (PKA-Cα) and the proteasome. The chymotrypsin-like activity of the sperm proteasome significantly increased after 5 min of capacitation (P < 0.001) and remained high for the remaining incubation time. Treatment with H89, KT5720 or KH7 significantly decreased the chymotrypsin-like activity of the proteasome (P < 0.001). IPP experiments indicated that PKA inhibition significantly modified phosphorylation of proteasome subunits. In addition, PKA-Cα colocalized with the proteasome in the equatorial segment and in the connecting piece, and co-immunoprecipitated with the proteasome. This is the first demonstration of sperm proteasome activity being directly regulated by SACY/PKA-Cα. This novel discovery extends our current knowledge of sperm physiology and may be used to manage sperm capacitation during assisted reproductive technology procedures.

scholarly journals Role of Calcium and EPAC in Norepinephrine-Induced Ghrelin Secretion

Endocrinology ◽  
2014 ◽  
Vol 155 (1) ◽  
pp. 98-107 ◽  
Author(s):  
Bharath K. Mani ◽  
Jen-Chieh Chuang ◽  
Lilja Kjalarsdottir ◽  
Ichiro Sakata ◽  
Angela K. Walker ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Intracellular Signaling ◽  
Endocrine Cells ◽  
Molecular Mechanisms ◽  
Phosphodiesterase Inhibitor ◽  
Intracellular Signaling Pathways ◽  
Ghrelin Secretion ◽  
Kinase A

Ghrelin is an orexigenic hormone secreted principally from a distinct population of gastric endocrine cells. Molecular mechanisms regulating ghrelin secretion are mostly unknown. Recently, norepinephrine (NE) was shown to enhance ghrelin release by binding to β1-adrenergic receptors on ghrelin cells. Here, we use an immortalized stomach-derived ghrelin cell line to further characterize the intracellular signaling pathways involved in NE-induced ghrelin secretion, with a focus on the roles of Ca2+ and cAMP. Several voltage-gated Ca2+ channel (VGCC) family members were found by quantitative PCR to be expressed by ghrelin cells. Nifedipine, a selective L-type VGCC blocker, suppressed both basal and NE-stimulated ghrelin secretion. NE induced elevation of cytosolic Ca2+ levels both in the presence and absence of extracellular Ca2+. Ca2+-sensing synaptotagmins Syt7 and Syt9 were also highly expressed in ghrelin cell lines, suggesting that they too help mediate ghrelin secretion. Raising cAMP with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine also stimulated ghrelin secretion, although such a cAMP-mediated effect likely does not involve protein kinase A, given the absence of a modulatory response to a highly selective protein kinase A inhibitor. However, pharmacological inhibition of another target of cAMP, exchange protein-activated by cAMP (EPAC), did attenuate both basal and NE-induced ghrelin secretion, whereas an EPAC agonist enhanced basal ghrelin secretion. We conclude that constitutive ghrelin secretion is primarily regulated by Ca2+ influx through L-type VGCCs and that NE stimulates ghrelin secretion predominantly through release of intracellular Ca2+. Furthermore, cAMP and its downstream activation of EPAC are required for the normal ghrelin secretory response to NE.

scholarly journals Role of vaspin in porcine ovary: effect on signaling pathways and steroid synthesis via GRP78 receptor and protein kinase A†

2020 ◽  
Vol 102 (6) ◽  
pp. 1290-1305 ◽  
Author(s):  
Patrycja Kurowska ◽  
Ewa Mlyczyńska ◽  
Monika Dawid ◽  
Joelle Dupont ◽  
Agnieszka Rak
Keyword(s):  
Protein Kinase ◽  
Western Blot ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Dependent Manner ◽  
Steroid Synthesis ◽  
Ovarian Cells ◽  
Vitro Effect ◽  
Kinase A

Abstract Vaspin, visceral-adipose-tissue-derived serine protease inhibitor, is involved in the development of obesity, insulin resistance, inflammation, and energy metabolism. Our previous study showed vaspin expression and its regulation in the ovary; however, the role of this adipokine in ovarian cells has never been studied. Here, we studied the in vitro effect of vaspin on various kinase-signaling pathways: mitogen-activated kinase (MAP3/1), serine/threonine kinase (AKT), signal transducer and activator of transcription 3 (STAT3) protein kinase AMP (PRKAA1), protein kinase A (PKA), and on expression of nuclear factor kappa B (NFKB2) as well as on steroid synthesis by porcine ovarian cells. By using western blot, we found that vaspin (1 ng/ml), in a time-dependent manner, increased phosphorylation of MAP3/1, AKT, STAT3, PRKAA1, and PKA, while it decreased the expression of NFKB2. We observed that vaspin, in a dose-dependent manner, increased the basal steroid hormone secretion (progesterone and estradiol), mRNA and protein expression of steroid enzymes using real-time PCR and western blot, respectively, and the mRNA of gonadotropins (FSHR, LHCGR) and steroids (PGR, ESR2) receptors. The stimulatory effect of vaspin on basal steroidogenesis was reversed when ovarian cells were cultured in the presence of a PKA pharmacological inhibitor (KT5720) and when GRP78 receptor was knocked down (siRNA). However, in the presence of insulin-like growth factor type 1 and gonadotropins, vaspin reduced steroidogenesis. Thus, vaspin, by activation of various signaling pathways and stimulation of basal steroid production via GRP78 receptor and PKA, could be a new regulator of porcine ovarian function.

scholarly journals Protein Kinase A, Ca2+/Calmodulin-Dependent Kinase II, and Calcineurin Regulate the Intracellular Trafficking of Myopodin between the Z-Disc and the Nucleus of Cardiac Myocytes

2007 ◽  
Vol 27 (23) ◽  
pp. 8215-8227 ◽  
Author(s):  
Christian Faul ◽  
Ashwini Dhume ◽  
Alison D. Schecter ◽  
Peter Mundel
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Cardiac Myocytes ◽  
Nuclear Import ◽  
Intracellular Signaling ◽  
Intracellular Signaling Pathway ◽  
Signaling Complex ◽  
Importin Α ◽  
Stress Dependent ◽  
Kinase A

ABSTRACT Spatial and temporal resolution of intracellular signaling can be achieved by compartmentalizing transduction units. Myopodin is a dual-compartment, actin-bundling protein that shuttles between the nucleus and the Z-disc of myocytes in a differentiation- and stress-dependent fashion. Importin α binding and nuclear import of myopodin are regulated by serine/threonine phosphorylation-dependent binding of myopodin to 14-3-3. Here we show that in the heart myopodin forms a Z-disc signaling complex with α-actinin, calcineurin, Ca2+/calmodulin-dependent kinase II (CaMKII), muscle-specific A-kinase anchoring protein, and myomegalin. Phosphorylation of myopodin by protein kinase A (PKA) or CaMKII mediates 14-3-3 binding and nuclear import in myoblasts. Dephosphorylation of myopodin by calcineurin abrogates 14-3-3β binding. Activation of PKA or inhibition of calcineurin in adult cardiac myocytes releases myopodin from the Z-disc and induces its nuclear import. The identification of myopodin as a direct target of PKA, CaMKII, and calcineurin defines a novel intracellular signaling pathway whereby changes in Z-disc dynamics may translate into compartmentalized signal transduction in the heart.

scholarly journals Genetic Analysis of the Kinetochore DASH Complex Reveals an Antagonistic Relationship with the Ras/Protein Kinase A Pathway and a Novel Subunit Required for Ask1 Association

2005 ◽  
Vol 25 (2) ◽  
pp. 767-778 ◽  
Author(s):  
Ju-mei Li ◽  
Yumei Li ◽  
Stephen J. Elledge
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Chromosome Segregation ◽  
Biochemical Analysis ◽  
Genetic Interaction ◽  
Negative Regulator ◽  
Ras Protein ◽  
Sister Chromatids ◽  
Pka Pathway ◽  
Kinase A

ABSTRACT DASH is a microtubule- and kinetochore-associated complex required for proper chromosome segregation and bipolar attachment of sister chromatids on the mitotic spindle. We have undertaken a genetic and biochemical analysis of the DASH complex and uncovered a strong genetic interaction of DASH with the Ras/protein kinase A (PKA) pathway. Overexpression of PDE2 or deletion of RAS2 rescued the temperature sensitivity of ask1-3 mutants. Ras2 negatively regulates DASH through the PKA pathway. Constitutive PKA activity caused by mutation of the negative regulator BCY1 is toxic to DASH mutants such as ask1 and dam1. In addition, we have discovered two novel subunits of DASH, Hsk2 and Hsk3 (helper of Ask1), which are microproteins of fewer than 75 amino acids, as dosage suppressors of ask1 mutants. These are essential genes that colocalize with DASH components on spindles and kinetochores and are present in the DASH complex. Mutants in hsk3 arrest cells in mitosis with short spindles and broken spindle structures characteristic of other DASH mutants. Hsk3 is critical for the integrity of the DASH complex because in hsk3 mutants the association of Dam1, Duo1, Spc34, and Spc19 with Ask1 is greatly diminished. We propose that Hsk3 acts to incorporate Ask1 into the DASH complex.

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