scholarly journals Flagellar adhesion-dependent regulation of Chlamydomonas adenylyl cyclase in vitro: a possible role for protein kinases in sexual signaling.

1994 ◽  
Vol 125 (3) ◽  
pp. 617-624 ◽  
Author(s):  
Y Zhang ◽  
W J Snell
Keyword(s):  
Protein Kinase ◽  
Adenylyl Cyclase ◽  
Kinase Inhibitor ◽  
Present Report ◽  
Cyclase Activity ◽  
Adenylyl Cyclase Activity ◽  
Vitro Assay ◽  
Free System

Interactions between adhesion molecules, agglutinins, on the surfaces of the flagella of mt+ and mt- gametes in Chlamydomonas rapidly generate a sexual signal, mediated by cAMP, that prepares the cells for fusion to form a zygote. The mechanism that couples agglutinin interactions to increased cellular levels of cAMP is unknown. In previous studies on the adenylyl cyclase in flagella of a single mating type (i.e., non-adhering flagella) we presented evidence that the gametic form of the enzyme, but not the vegetative form, was regulated by phosphorylation and dephosphorylation (Zhang, Y., E. M. Ross, and W. J. Snell. 1991. J. Biol. Chem. 266:22954-22959; Zhang, Y., and W. J. Snell. 1993. J. Biol. Chem. 268:1786-1791). In the present report we describe studies on regulation of flagellar adenylyl cyclase during adhesion in a cell-free system. The results show that the activity of gametic flagellar adenylyl cyclase is regulated by adhesion in vitro between flagella isolated from mt+ and mt- gametes. After mixing mt+ and mt- flagella together for 15 s in vitro, adenylyl cyclase activity was increased two- to threefold compared to that of the non-mixed (non-adhering), control flagella. This indicates that the regulation of gametic flagellar adenylyl cyclase during the early steps of fertilization is not mediated by signals from the cell body, but is a direct and primary response to interactions between mt+ and mt- agglutinins. By use of this in vitro assay, we discovered that 50 nM staurosporine (a protein kinase inhibitor) blocked adhesion-induced activation of adenylyl cyclase in vitro, while it had no effect on adenylyl cyclase activity of non-adhering gametic flagella. This same low concentration of staurosporine also inhibited adhesion-induced increases in vivo in cellular cAMP and blocked subsequent cellular responses to adhesion. Taken together, our results indicate that flagellar adenylyl cyclase in Chlamydomonas gametes is coupled to interactions between mt+ and mt- agglutinins by a staurosporine-sensitive activity, probably a protein kinase.

Analysis of the function of the 70-kilodalton cyclase-associated protein (CAP) by using mutants of yeast adenylyl cyclase defective in CAP binding

1993 ◽  
Vol 13 (7) ◽  
pp. 4087-4097
Author(s):  
J Wang ◽  
N Suzuki ◽  
Y Nishida ◽  
T Kataoka
Keyword(s):  
Heat Shock ◽  
Adenylyl Cyclase ◽  
Gene Replacement ◽  
Yeast Cells ◽  
Cyclase Activity ◽  
In Vitro Mutagenesis ◽  
Wild Type ◽  
Adenylyl Cyclase Activity

In Saccharomyces cerevisiae, adenylyl cyclase forms a complex with the 70-kDa cyclase-associated protein (CAP). By in vitro mutagenesis, we assigned a CAP-binding site of adenylyl cyclase to a small segment near its C terminus and created mutants which lost the ability to bind CAP. CAP binding was assessed first by observing the ability of the overproduced C-terminal 150 residues of adenylyl cyclase to sequester CAP, thereby suppressing the heat shock sensitivity of yeast cells bearing the activated RAS2 gene (RAS2Val-19), and then by immunoprecipitability of adenylyl cyclase activity with anti-CAP antibody and by direct measurement of the amount of CAP bound. Yeast cells whose chromosomal adenylyl cyclase genes were replaced by the CAP-nonbinding mutants possessed adenylyl cyclase activity fully responsive to RAS2 protein in vitro. However, they did not exhibit sensitivity to heat shock in the RAS2Val-19 background. When glucose-induced accumulation of cyclic AMP (cAMP) was measured in these mutants carrying RAS2Val-19, a rapid transient rise indistinguishable from that of wild-type cells was observed and a high peak level and following persistent elevation of the cAMP concentration characteristic of RAS2Val-19 were abolished. In contrast, in the wild-type RAS2 background, similar cyclase gene replacement did not affect the glucose-induced cAMP response. These results suggest that the association with CAP, although not involved in the in vivo response to the wild-type RAS2 protein, is somehow required for the exaggerated response of adenylyl cyclase to activated RAS2.

scholarly journals Analysis of the function of the 70-kilodalton cyclase-associated protein (CAP) by using mutants of yeast adenylyl cyclase defective in CAP binding.

1993 ◽  
Vol 13 (7) ◽  
pp. 4087-4097 ◽  
Author(s):  
J Wang ◽  
N Suzuki ◽  
Y Nishida ◽  
T Kataoka
Keyword(s):  
Heat Shock ◽  
Adenylyl Cyclase ◽  
Gene Replacement ◽  
Yeast Cells ◽  
Cyclase Activity ◽  
In Vitro Mutagenesis ◽  
Wild Type ◽  
Adenylyl Cyclase Activity

In Saccharomyces cerevisiae, adenylyl cyclase forms a complex with the 70-kDa cyclase-associated protein (CAP). By in vitro mutagenesis, we assigned a CAP-binding site of adenylyl cyclase to a small segment near its C terminus and created mutants which lost the ability to bind CAP. CAP binding was assessed first by observing the ability of the overproduced C-terminal 150 residues of adenylyl cyclase to sequester CAP, thereby suppressing the heat shock sensitivity of yeast cells bearing the activated RAS2 gene (RAS2Val-19), and then by immunoprecipitability of adenylyl cyclase activity with anti-CAP antibody and by direct measurement of the amount of CAP bound. Yeast cells whose chromosomal adenylyl cyclase genes were replaced by the CAP-nonbinding mutants possessed adenylyl cyclase activity fully responsive to RAS2 protein in vitro. However, they did not exhibit sensitivity to heat shock in the RAS2Val-19 background. When glucose-induced accumulation of cyclic AMP (cAMP) was measured in these mutants carrying RAS2Val-19, a rapid transient rise indistinguishable from that of wild-type cells was observed and a high peak level and following persistent elevation of the cAMP concentration characteristic of RAS2Val-19 were abolished. In contrast, in the wild-type RAS2 background, similar cyclase gene replacement did not affect the glucose-induced cAMP response. These results suggest that the association with CAP, although not involved in the in vivo response to the wild-type RAS2 protein, is somehow required for the exaggerated response of adenylyl cyclase to activated RAS2.

scholarly journals Cell adhesion-dependent inactivation of a soluble protein kinase during fertilization in Chlamydomonas.

1996 ◽  
Vol 7 (4) ◽  
pp. 515-527 ◽  
Author(s):  
Y Zhang ◽  
Y Luo ◽  
K Emmett ◽  
W J Snell
Keyword(s):  
Protein Kinase ◽  
Adenylyl Cyclase ◽  
Protein Tyrosine Kinase ◽  
Tyrosine Phosphatase ◽  
Protein Kinase Activity ◽  
Vitro Assay ◽  
Protein Tyrosine ◽  
Flagellar Protein

Within seconds after the flagella of mt+ and mt- Chlamydomonas gametes adhere during fertilization, their flagellar adenylyl cyclase is activated several fold and preparation for cell fusion is initiated. Our previous studies indicated that early events in this pathway, including control of adenylyl cyclase, are regulated by phosphorylation and dephosphorylation. Here, we describe a soluble, flagellar protein kinase activity that is regulated by flagellar adhesion. A 48-kDa, soluble flagellar protein was consistently phosphorylated in an in vitro assay in flagella isolated from nonadhering mt+ and mt- gametes, but not in flagella isolated from mt+ and mt- gametes that had been adhering for 1 min. Although the 48-kDa protein was present in the flagella isolated from adhering gametes, we demonstrate that its protein kinase was inactivated by flagellar adhesion. Immunoblot analysis and inhibitor studies indicate that the 48-kDa protein in nonadhering gametes is phosphorylated by a protein tyrosine kinase. In vivo experiments showing that the protein tyrosine phosphatase inhibitor sodium orthovanadate inhibits fertilization suggest that protein dephosphorylation may be required for signal transduction. The 48-kDa protein and its protein kinase may be among the first elements of a novel signalling pathway that couples interaction of flagellar adhesion molecules to gamete activation.

β-Adrenergic and antiadrenergic modulation of cardiac adenylyl cyclase is influenced by phosphorylation

2003 ◽  
Vol 285 (4) ◽  
pp. H1471-H1478 ◽  
Author(s):  
James G. Dobson ◽  
Lynne G. Shea ◽  
Richard A. Fenton
Keyword(s):  
Protein Kinase ◽  
Adenylyl Cyclase ◽  
Adrenergic Receptor ◽  
Kinase Inhibitor ◽  
Cyclase Activity ◽  
Adenylyl Cyclase Activity ◽  
Protein Substrates ◽  
Membrane Phosphorylation ◽  
Mediated Reduction ◽  
Kinase A

Adenosine protects the myocardium of the heart by exerting an antiadrenergic action via the adenosine A1 receptor (A1R). Because β1-adrenergic receptor (β1R) stimulation elicits myocardial protein phosphorylation, the present study investigated whether protein kinase A (PKA) catalyzed rat heart ventricular membrane phosphorylation affects the β1R adrenergic and A1R adenosinergic actions on adenylyl cyclase activity. Membranes were either phosphorylated with PKA in the absence/presence of a protein kinase inhibitor (PKI) or dephosphorylated with alkaline phosphatase (AP) and assayed for adenylyl cyclase activity (AC) in the presence of the β1R agonist isoproterenol (ISO) and/or the A1R agonist 2-chloro- N6-cyclopentyladenosine (CCPA). 32P incorporation into the protein substrates of 140–120, 43, and 29 kDa with PKA increased both the ISO-elicited activation of AC by 51–54% and the A1R-mediated reduction of the ISO-induced increase in AC by 29–50%, thereby yielding a total antiadrenergic effect of ∼78%. These effects of PKA were prevented by PKI. AP reduced the ISO-induced increase in AC and eliminated the antiadrenergic effect of CCPA. Immunoprecipitation of the solubilized membrane adenylyl cyclase with the use of a polyclonal adenylyl cyclase VI antibody indicated that the enzyme is phosphorylated by PKA. These results indicate that the cardioprotective effect of adenosine afforded by its antiadrenergic action is facilitated by cardiac membrane phosphorylation.

Impaired G-protein-stimulated adenylyl cyclase activity in Alzheimer's disease brain is not accompanied by reduced cyclic-AMP-dependent protein kinase A activity

1996 ◽  
Vol 737 (1-2) ◽  
pp. 155-161 ◽  
Author(s):  
Willy L Bonkale ◽  
Johan Fastbom ◽  
Birgitta Wiehager ◽  
Rivka Ravid ◽  
Bengt Winblad ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Adenylyl Cyclase ◽  
G Protein ◽  
Cyclase Activity ◽  
Adenylyl Cyclase Activity ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Kinase A

Abstract 212: Inhibition of Protein Phosphatase 2A (PP2A) Leads to Beta-adrenergic Receptor Dysfunction With Cardiac Stress Following Pressure-overload Hypertrophy

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Arunachal Chatterjee ◽  
Neelakantan Vasudevan ◽  
Maradumane Mohan ◽  
Elizabeth Martelli ◽  
John George ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Adenylyl Cyclase ◽  
Cardiac Dysfunction ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Cyclase Activity ◽  
Adenylyl Cyclase Activity ◽  
Cardiac Stress ◽  
Phosphatase 2A

Beta-Adrenergic receptors (bARs) play a key role in regulating cardiac function. Loss of surface receptors and desensitization (impaired G-protein coupling) of bARs are hallmarks of a failing heart. Desensitization occurs by phosphorylation of bARs. The bARs are resensitized by protein phosphatase 2A (PP2A) mediated dephosphorylation in the endosomes before recycling to the plasma membrane. While mechanisms of desensitization are well understood, little is known about mechanisms regulating resensitization. Our previous work has shown that PI3Kg phosphorylates an endogenous inhibitor of PP2A (I2PP2A) on serine 9 & 93, which then robustly binds to PP2A inhibiting bAR resensitization. Since it is not known whether resensitization is altered in response to cardiac stress or whether altered bAR resensitization contributes to cardiac hypertrophy and failure, we generated transgenic mice with cardiomyocyte specific overexpression of wild type I2PP2A (WT I2PP2A Tg), I2PP2A phospho-mimetic mutants S9, 93D and mutants with constitutively dephosphorylated S9, 93A state. To test whether resensitization is critical in the development of bAR dysfunction during cardiac hypertrophy, WT I2PP2A Tg mice were subjected to transverse aortic constriction (TAC) for 8 weeks. Echocardiographic analysis post-TAC showed that WT I2PP2A Tg mice had accelerated cardiac dysfunction compared to their littermate controls [HW (mg)/BW(g): Sham: WT - 4.83, WT I2PP2A Tg - 4.82, TAC: WT- 6.47, WT I2PP2A Tg - 7.61; %EF: Sham: WT - 83.53, WT I2PP2A Tg - 74.72, TAC: WT - 70.47, WT I2PP2A Tg - 49.62]. To directly test whether resensitization mechanisms are altered, plasma membranes and endosomes were isolated and in vitro Adenylyl Cyclase activity assessed. Our studies show that compared to littermate controls, WT I2PP2A Tg had altered in vitro adenylyl cyclase activity showing that resensitization mechanisms in the endosomes may in part, contribute to cardiac dysfunction. Mechanistic underpinnings of the resensitization pathways using the I2PP2A S9, 93A and S9, 93D will be presented showing that bAR resensitization a process considered passive is altered in conditions of cardiac stress that in part may contribute to bAR dysfunction leading to cardiac hypertrophy and heart failure.

Phosphorylation of Argonaute 2 at serine-387 facilitates its localization to processing bodies

2008 ◽  
Vol 413 (3) ◽  
pp. 429-436 ◽  
Author(s):  
Yan Zeng ◽  
Heidi Sankala ◽  
Xiaoxiao Zhang ◽  
Paul R. Graves
Keyword(s):  
Protein Kinase ◽  
P38 Mapk ◽  
Kinase Inhibitor ◽  
Mapk Pathway ◽  
Phosphorylation Site ◽  
Mitogen Activated Protein Kinase ◽  
Processing Bodies ◽  
Mitogen Activated Protein

Ago (Argonaute) proteins are essential effectors of RNA-mediated gene silencing. To explore potential regulatory mechanisms for Ago proteins, we examined the phosphorylation of human Ago2. We identified serine-387 as the major Ago2 phosphorylation site in vivo. Phosphorylation of Ago2 at serine-387 was significantly induced by treatment with sodium arsenite or anisomycin, and arsenite-induced phosphorylation was inhibited by a p38 MAPK (mitogen-activated protein kinase) inhibitor, but not by inhibitors of JNK (c-Jun N-terminal kinase) or MEK [MAPK/ERK (extracellular-signal-regulated kinase) kinase]. MAPKAPK2 (MAPK-activated protein kinase-2) phosphorylated bacterially expressed full-length human Ago2 at serine-387 in vitro, but not the S387A mutant. Finally, mutation of serine-387 to an alanine residue or treatment of cells with a p38 MAPK inhibitor reduced the localization of Ago2 to processing bodies. These results suggest a potential regulatory mechanism for RNA silencing acting through Ago2 serine-387 phosphorylation mediated by the p38 MAPK pathway.

scholarly journals Cdc25 Inhibited In Vivo and In Vitro by Checkpoint Kinases Cds1 and Chk1

1999 ◽  
Vol 10 (4) ◽  
pp. 833-845 ◽  
Author(s):  
Beth Furnari ◽  
Alessandra Blasina ◽  
Michael N. Boddy ◽  
Clare H. McGowan ◽  
Paul Russell
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinases ◽  
In Vitro Assay ◽  
Vitro Assay ◽  
Replication Checkpoint ◽  
Checkpoint Kinases ◽  
Mitotic Kinase ◽  
Mitotic Delay

In the fission yeast Schizosaccharomyces pombe, the protein kinase Cds1 is activated by the S–M replication checkpoint that prevents mitosis when DNA is incompletely replicated. Cds1 is proposed to regulate Wee1 and Mik1, two tyrosine kinases that inhibit the mitotic kinase Cdc2. Here, we present evidence from in vivo and in vitro studies, which indicates that Cds1 also inhibits Cdc25, the phosphatase that activates Cdc2. In an in vivo assay that measures the rate at which Cdc25 catalyzes mitosis, Cds1 contributed to a mitotic delay imposed by the S–M replication checkpoint. Cds1 also inhibited Cdc25-dependent activation of Cdc2 in vitro. Chk1, a protein kinase that is required for the G2–M damage checkpoint that prevents mitosis while DNA is being repaired, also inhibited Cdc25 in the in vitro assay. In vitro, Cds1 and Chk1 phosphorylated Cdc25 predominantly on serine-99. The Cdc25 alanine-99 mutation partially impaired the S–M replication and G2–M damage checkpoints in vivo. Thus, Cds1 and Chk1 seem to act in different checkpoint responses to regulate Cdc25 by similar mechanisms.

Sign in / Sign up

Export Citation Format

Share Document