scholarly journals Identification of a clinically homogenous subgroup of benign cortisol-secreting adrenocortical tumors characterized by alterations of the protein kinase A (PKA) subunits and high PKA activity.

2008 ◽  
Vol 158 (6) ◽  
pp. 829-839 ◽  
Author(s):  
C Vincent-Dejean ◽  
L Cazabat ◽  
L Groussin ◽  
K Perlemoine ◽  
G Fumey ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Carney Complex ◽  
Catalytic Subunits ◽  
Regulatory Subunits ◽  
Adrenocortical Tumors ◽  
Camp Pathway ◽  
Adrenocortical Adenomas ◽  
Pka Pathway ◽  
Kinase A

ObjectiveThe cAMP/protein kinase A (PKA) pathway plays an important role in endocrine tumorigenesis. PKA is a heterotetramer with two regulatory subunits (four genes:PRKAR1A,PRKAR1B,PRKAR2A,PRKAR2B) and two catalytic subunits. InactivatingPRKAR1Amutations have been observed in Carney complex and a subset of adrenocortical tumors (ACT). This study was designed to search for other alterations of PKA in ACT, and to establish their correlation with the clinical characteristics.MethodsIn this study, 35 ACT (10 non-secreting adrenocortical adenomas (ACA-NS), 13 cortisol-secreting adenomas (ACA-S), and 12 malignant s (ACC)) were studied. PKA subunits were studied by western blot and RT-qPCR. The PKA activity was measured.ResultsA subgroup of ACA-S with a 96% R2B protein decrease by comparison with normal adrenal (4.1%±4 vs 100%±19,P<0.001) was identified, ACA-S2 (6/13). By contrast, no differences were observed in ACC and ACA-NS. The level of R1A mRNA was decreased in ACA-S (P<0.001), but not the level of R2B mRNA. No mutation of the R2B gene was detected in ACA-S2. The ACA-S2 group with loss of R2B protein showed a threefold higher basal PKA activity than the ACA with normal R2B protein (3.37±0.31 vs 1.00±0.20,P<0.0001). The ACA-S2 tumors with the loss of the R2B protein presented a homogenous phenotype and were all small benign cortisol-secreting tumors.ConclusionThis loss of PRKAR2B protein due to a post-transcriptional mechanism in ACA-S is a new mechanism of cAMP pathway dysregulation in adrenocortical tumorigenesis. It defines a new subtype of secreting adenomas with high basal PKA activity presenting a homogenous clinical phenotype.

scholarly journals Noncanonical protein kinase A activation by oligomerization of regulatory subunits as revealed by inherited Carney complex mutations

2021 ◽  
Vol 118 (21) ◽  
pp. e2024716118
Author(s):  
Naeimeh Jafari ◽  
Jason Del Rio ◽  
Madoka Akimoto ◽  
Jung Ah Byun ◽  
Stephen Boulton ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Molecular Mechanisms ◽  
Carney Complex ◽  
Regulatory Subunit ◽  
Regulatory Subunits ◽  
Inhibitory Function ◽  
Wide Range ◽  
Liver Cancers ◽  
Kinase A

Familial mutations of the protein kinase A (PKA) R1α regulatory subunit lead to a generalized predisposition for a wide range of tumors, from pituitary adenomas to pancreatic and liver cancers, commonly referred to as Carney complex (CNC). CNC mutations are known to cause overactivation of PKA, but the molecular mechanisms underlying such kinase overactivity are not fully understood in the context of the canonical cAMP-dependent activation of PKA. Here, we show that oligomerization-induced sequestration of R1α from the catalytic subunit of PKA (C) is a viable mechanism of PKA activation that can explain the CNC phenotype. Our investigations focus on comparative analyses at the level of structure, unfolding, aggregation, and kinase inhibition profiles of wild-type (wt) PKA R1α, the A211D and G287W CNC mutants, as well as the cognate acrodysostosis type 1 (ACRDYS1) mutations A211T and G287E. The latter exhibit a phenotype opposite to CNC with suboptimal PKA activation compared with wt. Overall, our results show that CNC mutations not only perturb the classical cAMP-dependent allosteric activation pathway of PKA, but also amplify significantly more than the cognate ACRDYS1 mutations nonclassical and previously unappreciated activation pathways, such as oligomerization-induced losses of the PKA R1α inhibitory function.

scholarly journals Protein Kinase A Catalytic and Regulatory Subunits Interact Differently in Various Areas of Mouse Brain

2020 ◽  
Vol 21 (9) ◽  
pp. 3051
Author(s):  
Carla Mucignat-Caretta ◽  
Antonio Caretta
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Mouse Brain ◽  
Stria Terminalis ◽  
Interaction Patterns ◽  
Brain Areas ◽  
Catalytic Subunits ◽  
Regulatory Subunits ◽  
Multiple Interaction ◽  
Kinase A

Protein kinase A (PKA) are tetramers of two catalytic and two regulatory subunits, docked at precise intracellular sites to provide localized phosphorylating activity, triggered by cAMP binding to regulatory subunits and subsequent dissociation of catalytic subunits. It is unclear whether in the brain PKA dissociated subunits may also be found. PKA catalytic subunit was examined in various mouse brain areas using immunofluorescence, equilibrium binding and western blot, to reveal its location in comparison to regulatory subunits type RI and RII. In the cerebral cortex, catalytic subunits colocalized with clusters of RI, yet not all RI clusters were bound to catalytic subunits. In stria terminalis, catalytic subunits were in proximity to RI but separated from them. Catalytic subunits clusters were also present in the corpus striatum, where RII clusters were detected, whereas RI clusters were absent. Upon cAMP addition, the distribution of regulatory subunits did not change, while catalytic subunits were completely released from regulatory subunits. Unpredictably, catalytic subunits were not solubilized; instead, they re-targeted to other binding sites within the tissue, suggesting local macromolecular reorganization. Hence, the interactions between catalytic and regulatory subunits of protein kinase A consistently vary in different brain areas, supporting the idea of multiple interaction patterns.

scholarly journals Peroxiredoxin promotes longevity and H2O2-resistance in yeast through redox-modulation of protein kinase A

2019 ◽  
Author(s):  
Friederike Roger ◽  
Cecilia Picazo ◽  
Wolfgang Reiter ◽  
Marouane Libiad ◽  
Chikako Asami ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Significant Proportion ◽  
Catalytic Subunits ◽  
Kinase Activation ◽  
H2o2 Resistance ◽  
Nutrient Signaling ◽  
Scavenging Enzymes ◽  
Pka Pathway ◽  
Kinase A

AbstractPeroxiredoxins are H2O2scavenging enzymes that also carry H2O2signaling and chaperone functions. In yeast, the major cytosolic peroxiredoxin, Tsa1 is required for both promoting resistance to H2O2and extending lifespan upon caloric restriction. We show here that Tsa1 effects both these functions not by scavenging H2O2, but by repressing the nutrient signaling Ras-cAMP-PKA pathway at the level of the protein kinase A (PKA) enzyme. Tsa1 stimulates sulfenylation of cysteines in the PKA catalytic subunit by H2O2and a significant proportion of the catalytic subunits are glutathionylated on two cysteine residues. Redox modification of the conserved Cys243 inhibits the phosphorylation of a conserved Thr241 in the kinase activation loop and enzyme activity, and preventing Thr241 phosphorylation can overcome the H2O2sensitivity of Tsa1-deficient cells. Results support a model of aging where nutrient signaling pathways constitute hubs integrating information from multiple aging-related conduits, including a peroxiredoxin-dependent response to H2O2.

Differential expression of protein kinase A catalytic and regulatory subunits in adrenocortical adenomas

2016 ◽  
Author(s):  
Isabel Weigand ◽  
Cristina Ronchi ◽  
Marthe Rizk-Rabin ◽  
Dalmazi Guido Di ◽  
Davide Calebiro ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Differential Expression ◽  
Regulatory Subunits ◽  
Adrenocortical Adenomas ◽  
Kinase A

scholarly journals Peroxiredoxin promotes longevity and H2O2-resistance in yeast through redox-modulation of protein kinase A

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Friederike Roger ◽  
Cecilia Picazo ◽  
Wolfgang Reiter ◽  
Marouane Libiad ◽  
Chikako Asami ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Significant Proportion ◽  
Catalytic Subunits ◽  
Kinase Activation ◽  
H2o2 Resistance ◽  
Nutrient Signaling ◽  
Scavenging Enzymes ◽  
Pka Pathway ◽  
Kinase A

Peroxiredoxins are H2O2 scavenging enzymes that also carry out H2O2 signaling and chaperone functions. In yeast, the major cytosolic peroxiredoxin, Tsa1 is required for both promoting resistance to H2O2 and extending lifespan upon caloric restriction. We show here that Tsa1 effects both these functions not by scavenging H2O2, but by repressing the nutrient signaling Ras-cAMP-PKA pathway at the level of the protein kinase A (PKA) enzyme. Tsa1 stimulates sulfenylation of cysteines in the PKA catalytic subunit by H2O2 and a significant proportion of the catalytic subunits are glutathionylated on two cysteine residues. Redox modification of the conserved Cys243 inhibits the phosphorylation of a conserved Thr241 in the kinase activation loop and enzyme activity, and preventing Thr241 phosphorylation can overcome the H2O2 sensitivity of Tsa1-deficient cells. Results support a model of aging where nutrient signaling pathways constitute hubs integrating information from multiple aging-related conduits, including a peroxiredoxin-dependent response to H2O2.

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.

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