scholarly journals PKA-RII subunit phosphorylation precedes activation by cAMP and regulates activity termination

2018 ◽  
Vol 217 (6) ◽  
pp. 2167-2184 ◽  
Author(s):  
Jörg Isensee ◽  
Melanie Kaufholz ◽  
Matthias J. Knape ◽  
Jan Hasenauer ◽  
Hanna Hammerich ◽  
...  
Keyword(s):  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Mechanistic Modeling ◽  
Type Ii ◽  
Dependent Protein Kinase ◽  
Catalytic Subunits ◽  
Dependent Protein ◽  
Inhibitory Domain ◽  
Activity Dependent

Type II isoforms of cyclic adenosine monophosphate (cAMP)–dependent protein kinase A (PKA-II) contain a phosphorylatable epitope within the inhibitory domain of RII subunits (pRII) with still unclear function. In vitro, RII phosphorylation occurs in the absence of cAMP, whereas staining of cells with pRII-specific antibodies revealed a cAMP-dependent pattern. In sensory neurons, we found that increased pRII immunoreactivity reflects increased accessibility of the already phosphorylated RII epitope during cAMP-induced opening of the tetrameric RII2:C2 holoenzyme. Accordingly, induction of pRII by cAMP was sensitive to novel inhibitors of dissociation, whereas blocking catalytic activity was ineffective. Also in vitro, cAMP increased the binding of pRII antibodies to RII2:C2 holoenzymes. Identification of an antibody specific for the glycine-rich loop of catalytic subunits facing the pRII-epitope confirmed activity-dependent binding with similar kinetics, proving that the reassociation is rapid and precisely controlled. Mechanistic modeling further supported that RII phosphorylation precedes cAMP binding and controls the inactivation by modulating the reassociation involving the coordinated action of phosphodiesterases and phosphatases.

Ufd1 phosphorylation at serine 229 negatively regulates endoplasmic reticulum-associated degradation by inhibiting the interaction of Ufd1 with VCP

2019 ◽  
Vol 476 (18) ◽  
pp. 2561-2577
Author(s):  
Quynh-Anh Thi Nguyen ◽  
Juyong Choi ◽  
Jin Kuk Yang ◽  
Sang Yoon Lee
Keyword(s):  
Endoplasmic Reticulum ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Calyculin A ◽  
Dependent Protein Kinase ◽  
Binding Ability ◽  
Dependent Protein ◽  
Cyclase Activator

Abstract Misfolded proteins in the endoplasmic reticulum (ER) are removed through multistep processes termed ER-associated degradation (ERAD). Valosin-containing protein (VCP) plays a crucial role in ERAD as the interaction of ubiquitin fusion degradation protein 1 (Ufd1) with VCP via its SHP box motif (228F-S-G-S-G-N-R-L235) is required for ERAD. However, the mechanisms by which the VCP–Ufd1 interaction is regulated are not well understood. Here, we found that the serine 229 residue located in the Ufd1 SHP box is phosphorylated in vitro and in vivo by cyclic adenosine monophosphate-dependent protein kinase A (PKA), with this process being enhanced by either forskolin (an adenylyl cyclase activator) or calyculin A (a protein phosphatase inhibitor). Moreover, a phosphomimetic mutant (S229D) of Ufd1 as well as treatment by forskolin, calyculin A, or activated PKA strongly reduced Ufd1 binding affinity for VCP. Consistent with this, the Ufd1 S229D mutant significantly inhibited ERAD leading to the accumulation of ERAD substrates such as a tyrosinase mutant (C89R) and 3-hydroxy-3-methylglutaryl coenzyme A reductase. However, a non-phosphorylatable Ufd1 mutant (S229A) retained VCP-binding ability and was less effective in blocking ERAD. Collectively, our results support that Ufd1 S229 phosphorylation status mediated by PKA serves as a key regulatory point for the VCP–Ufd1 interaction and functional ERAD.

PKA Cβ: a forgotten catalytic subunit of cAMP-dependent protein kinase opens new windows for PKA signaling and disease pathologies

2021 ◽  
Vol 478 (11) ◽  
pp. 2101-2119
Author(s):  
Susan S. Taylor ◽  
Maximilian Wallbott ◽  
Erik M. F. Machal ◽  
Kristoffer Søberg ◽  
Faihaa Ahmed ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Splice Variants ◽  
Large Family ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Dependent Protein Kinase ◽  
Catalytic Core ◽  
Catalytic Subunits ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

3′,5′-cyclic adenosine monophosphate (cAMP) dependent protein kinase or protein kinase A (PKA) has served as a prototype for the large family of protein kinases that are crucially important for signal transduction in eukaryotic cells. The PKA catalytic subunits are encoded by the two major genes PRKACA and PRKACB, respectively. The PRKACA gene encodes two known splice variants, the ubiquitously expressed Cα1 and the sperm-specifically expressed Cα2. In contrast, the PRKACB gene encodes several splice variants expressed in a highly cell and tissue-specific manner. The Cβ proteins are called Cβ1, Cβ2, Cβ3, Cβ4 and so-called abc variants of Cβ3 and Cβ4. Whereas Cβ1 is ubiquitously expressed, Cβ2 is enriched in immune cells and the Cβ3, Cβ4 and their abc variants are solely expressed in neuronal cells. All Cα and Cβ splice variants share a kinase-conserved catalytic core and a C-terminal tail encoded by exons 2 through 10 in the PRKACA and PRKACB genes, respectively. All Cα and Cβ splice variants with the exception of Cα1 and Cβ1 are hyper-variable at the N-terminus. Here, we will discuss how the PRKACA and PRKACB genes have developed as paralogs that encode distinct and functionally non-redundant proteins. The fact that Cα and Cβ splice variant mutations are associated with numerous diseases further opens new windows for PKA-induced disease pathologies.

scholarly journals Dibutyryl cyclic adenosine monophosphate reduces expression of c-myc during HL-60 differentiation

Blood ◽  
1986 ◽  
Vol 68 (2) ◽  
pp. 412-416
Author(s):  
SS Jr McCachren ◽  
J Nichols ◽  
RE Kaufman ◽  
JE Niedel
Keyword(s):  
Leukemia Cell ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Mechanisms Of Action ◽  
Promyelocytic Leukemia ◽  
Leukemia Cell Line ◽  
Dependent Protein Kinase ◽  
Rna Transcripts ◽  
Dependent Protein ◽  
Promyelocytic Leukemia Cell Line

The human promyelocytic leukemia cell line HL-60 is induced to differentiate along a myelocytic pathway by dibutyryl cyclic adenosine monophosphate (dbcAMP). Other cAMP analogs are ineffective as inducing agents. The effect of these compounds on expression of c-myc was investigated using a DNA probe for c-myc to detect RNA transcripts. The dose response and time to commitment for reduction in c-myc expression with dbcAMP was similar to the findings for phenotypic changes. Bromo- cyclic AMP and butyrate alone caused no changes in c-myc expression in 24 hours, but demonstrated dramatic synergism together, suggesting that butyrate contributes in part to the effects of dbcAMP. Evidence for mechanisms of action of cAMP other than activation of the cAMP- dependent protein kinase is reviewed.

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