scholarly journals Protein Kinase A-Mediated Septin7 Phosphorylation Disrupts Septin Filaments and Ciliogenesis

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 361
Author(s):  
Han-Yu Wang ◽  
Chun-Hsiang Lin ◽  
Yi-Ru Shen ◽  
Ting-Yu Chen ◽  
Chia-Yih Wang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Primary Cilia ◽  
Cell Growth And Migration ◽  
Filament Dynamics ◽  
Gtp Binding ◽  
Cilia Formation ◽  
And Migration ◽  
Septin Filament ◽  
Kinase A

Septins are GTP-binding proteins that form heteromeric filaments for proper cell growth and migration. Among the septins, septin7 (SEPT7) is an important component of all septin filaments. Here we show that protein kinase A (PKA) phosphorylates SEPT7 at Thr197, thus disrupting septin filament dynamics and ciliogenesis. The Thr197 residue of SEPT7, a PKA phosphorylating site, was conserved among different species. Treatment with cAMP or overexpression of PKA catalytic subunit (PKACA2) induced SEPT7 phosphorylation, followed by disruption of septin filament formation. Constitutive phosphorylation of SEPT7 at Thr197 reduced SEPT7‒SEPT7 interaction, but did not affect SEPT7‒SEPT6‒SEPT2 or SEPT4 interaction. Moreover, we noted that SEPT7 interacted with PKACA2 via its GTP-binding domain. Furthermore, PKA-mediated SEPT7 phosphorylation disrupted primary cilia formation. Thus, our data uncover the novel biological function of SEPT7 phosphorylation in septin filament polymerization and primary cilia formation.

Protein kinase A-mediated septin7 phosphorylation disrupts septin filaments and ciliogenesis

2020 ◽  
Author(s):  
Chun-Hsiang Lin ◽  
Ting-Yu Chen ◽  
Yi-Ru Shen ◽  
Chia-Yih Wang ◽  
Pao-Lin Kuo
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Primary Cilia ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Cell Growth And Migration ◽  
Gtp Binding ◽  
Cilia Formation ◽  
Septin Filament ◽  
Kinase A

Abstract Septins are GTP-binding proteins that form heteromeric filaments for proper cell growth and migration. Among these septins, septin7 (SEPT7) is an important component of all septin filaments. Here we showed that protein kinase A (PKA) phosphorylates SEPT7 at Thr197 thus disrupting septin filament dynamics and ciliogenesis. The PKA targeting site at Thr197 of SEPT7 was conserved among species. Treatment of cAMP or overexpression of PKA catalytic subunit (PKACA2) induced SEPT7 phosphorylation. SEPT7 phosphorylation at Thr197 disrupted septin filament formation by reducing SEPT7-SEPT7 interaction, but not affected SEPT7-SEPT6-SEPT2 or SEPT4 interaction. Besides, overexpression of phosphomimetic SEPT7 mutant (T197E) disrupted endogenous SEPT7 filaments suggesting T197E had dominant negative effect on septin filament polymerization. We also identified SEPT7 interacted with the PKACA2 via the GTP-binding domain. Furthermore, PKA-mediated SEPT7 phosphorylation disrupted primary cilia formation. Thus, our data uncover the novel biological function of SEPT7 phosphorylation in septin filament polymerization and primary cilia formation.

scholarly journals A tripartite cooperative mechanism confers resistance of the protein kinase A catalytic subunit to dephosphorylation

2020 ◽  
Vol 295 (10) ◽  
pp. 3316-3329
Author(s):  
Tung O. Chan ◽  
Roger S. Armen ◽  
Santosh Yadav ◽  
Sushrut Shah ◽  
Jin Zhang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Catalytic Subunit ◽  
Site Directed Mutagenesis ◽  
Airway Smooth Muscle Cells ◽  
Activation Loop ◽  
Allosteric Sites ◽  
And Migration ◽  
Kinase A ◽  
In Cells

Phosphorylation of specific residues in the activation loops of AGC kinase group (protein kinase A, G, and C families) is required for activity of most of these kinases, including the catalytic subunit of PKA (PKAc). Although many phosphorylated AGC kinases are sensitive to phosphatase-mediated dephosphorylation, the PKAc activation loop uniquely resists dephosphorylation, rendering it “constitutively” phosphorylated in cells. Previous biophysical experiments and structural modeling have suggested that the N-terminal myristoylation signal and the C-terminal FXXF motif in PKAc regulate its thermal stability and catalysis. Here, using site-directed mutagenesis, molecular modeling, and in cell-free and cell-based systems, we demonstrate that substitutions of either the PKAc myristoylation signal or the FXXF motif only modestly reduce phosphorylation and fail to affect PKAc function in cells. However, we observed that these two sites cooperate with an N-terminal FXXW motif to cooperatively establish phosphatase resistance of PKAc while not affecting kinase-dependent phosphorylation of the activation loop. We noted that this tripartite cooperative mechanism of phosphatase resistance is functionally relevant, as demonstrated by changes in morphology, adhesion, and migration of human airway smooth muscle cells transfected with PKAc variants containing amino acid substitutions in these three sites. These findings establish that three allosteric sites located at the PKAc N and C termini coordinately regulate the phosphatase sensitivity of this enzyme. This cooperative mechanism of phosphatase resistance of AGC kinase opens new perspectives toward therapeutic manipulation of kinase signaling in disease.

scholarly journals The regulatory 1α subunit of protein kinase A modulates renal cystogenesis

2017 ◽  
Vol 313 (3) ◽  
pp. F677-F686 ◽  
Author(s):  
Hong Ye ◽  
Xiaofang Wang ◽  
Megan M. Constans ◽  
Caroline R. Sussman ◽  
Fouad T. Chebib ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Primary Cilia ◽  
Control Cell ◽  
Carney Complex ◽  
Regulatory Subunit ◽  
Renal Cystic Disease ◽  
Kinase A

The failure of the polycystins (PCs) to function in primary cilia is thought to be responsible for autosomal dominant polycystic kidney disease (ADPKD). Primary cilia integrate multiple cellular signaling pathways, including calcium, cAMP, Wnt, and Hedgehog, which control cell proliferation and differentiation. It has been proposed that mutated PCs result in reduced intracellular calcium, which in turn upregulates cAMP, protein kinase A (PKA) signaling, and subsequently other proliferative signaling pathways. However, the role of PKA in ADPKD has not been directly ascertained in vivo, although the expression of the main regulatory subunit of PKA in cilia and other compartments (PKA-RIα, encoded by PRKAR1A) is increased in a mouse model orthologous to ADPKD. Therefore, we generated a kidney-specific knockout of Prkar1a to examine the consequences of constitutive upregulation of PKA on wild-type and Pkd1 hypomorphic ( Pkd1RC) backgrounds. Kidney-specific loss of Prkar1a induced renal cystic disease and markedly aggravated cystogenesis in the Pkd1RC models. In both settings, it was accompanied by upregulation of Src, Ras, MAPK/ERK, mTOR, CREB, STAT3, Pax2 and Wnt signaling. On the other hand, Gli3 repressor activity was enhanced, possibly contributing to hydronephrosis and impaired glomerulogenesis in some animals. To assess the relevance of these observations in humans we looked for and found evidence for kidney and liver cystic phenotypes in the Carney complex, a tumoral syndrome caused by mutations in PRKAR1A. These observations expand our understanding of the pathogenesis of ADPKD and demonstrate the importance of PRKAR1A highlighting PKA as a therapeutic target in ADPKD.

scholarly journals In spermatozoa, Stat1 is activated during capacitation and the acrosomal reaction

Reproduction ◽  
2007 ◽  
Vol 134 (3) ◽  
pp. 425-433 ◽  
Author(s):  
Yadira Bastián ◽  
Armando Zepeda-Bastida ◽  
Salvador Uribe ◽  
Adela Mújica
Keyword(s):  
Transcription Factors ◽  
Protein Kinase ◽  
Embryonic Development ◽  
Protein Kinase A ◽  
Signal Transducer ◽  
Acrosomal Reaction ◽  
Specific Proteins ◽  
Spatio Temporal ◽  
And Migration ◽  
Kinase A

A role for sperm-specific proteins during the early embryonic development has been suggested by a number of recent studies. However, little is known about the participation of transcription factors in that stage. Here, we show that the signal transducer and activator of transcription 1 (Stat1), but not Stat4, was phosphorylated in response to capacitation and the acrosomal reaction (AR). Moreover, Stat1 phosphorylation correlated with changes in its localization: during capacitation, Stat1 moved from the cytoplasm to the theca/flagellum fraction. During AR, Stat1 phosphorylation increased again. In addition, blocking protein kinase A (PKA) and PKC during capacitation abolished both phosphorylation and migration of Stat1. Our results show tight spatio–temporal rearrangements of Stat1, suggesting that after fertilization Stat1 participates in the first rounds of transcription within the male pronucleus.

scholarly journals Functional Roles of Protein Kinase A (PKA) and Exchange Protein Directly Activated by 3′,5′-Cyclic Adenosine 5′-Monophosphate (cAMP) 2 (EPAC2) in cAMP-Mediated Actions in Adrenocortical Cells

Endocrinology ◽  
2010 ◽  
Vol 151 (5) ◽  
pp. 2151-2161 ◽  
Author(s):  
Linda Aumo ◽  
Marte Rusten ◽  
Gunnar Mellgren ◽  
Marit Bakke ◽  
Aurélia E. Lewis
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Steroid Hormones ◽  
Steroid Hormone ◽  
Regulatory Protein ◽  
Adrenocortical Cancer ◽  
Hormone Production ◽  
Genes Encoding ◽  
And Migration ◽  
Kinase A

In the adrenal cortex, the biosynthesis of steroid hormones is controlled by the pituitary-derived hormone ACTH. The functions of ACTH are principally relayed by activating cAMP-dependent signaling pathways leading to the induction of genes encoding enzymes involved in the conversion of cholesterol to steroid hormones. Previously, protein kinase A (PKA) was thought to be the only direct effector of cAMP. However, the discovery of the cAMP sensors, exchange proteins directly activated by cAMP (EPAC1 and 2), has led to a reevaluation of this assumption. In the present study, we demonstrate the occurrence of the EPAC2 splicing variant EPAC2B in adrenocortical cancer cells. Immunocytochemistry demonstrated that EPAC2B is localized predominantly in the nucleus. EPAC2B is functional because it activates Rap1 in these cells. Using the cAMP analogs 8-p-chlorophenylthio-2′-O-methyl-cAMP and N6-benzoyl-cAMP, which specifically activate EPAC1/2 and PKA, respectively, we evaluated the contribution of these factors in steroid hormone production, cell morphology, actin reorganization, and migration. We demonstrate that the expression of cAMP-inducible factors involved in steroidogenesis (steroidogenic acute regulatory protein, cytochrome P450 11A1 and 17, and nerve growth factor-induced clone B) and the cAMP-induced biosynthesis of steroid hormones (cortisol and aldosterone) are mediated by PKA and not by EPAC2B. In contrast, both PKA- and EPAC-specific cAMP analogs induced cell rounding, loss of stress fibers, and blocked migration. Taken together, the presented data confirm PKA as the central cAMP mediator in steroid hormone production and reveal the involvement of EPAC2B in cAMP-induced effects on cytoskeleton integrity and cell migration.

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