Protein Phosphatase 2A Is Involved in the Regulation of Protein Kinase A Signaling Pathway during in Vitro Chondrogenesis

2002 ◽  
Vol 275 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Róza Zákány ◽  
Kornélia Szűcs ◽  
Éva Bakó ◽  
Szabolcs Felszeghy ◽  
Gabriella Czifra ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Signaling Pathway ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Phosphatase 2A ◽  
Kinase A

scholarly journals Protein kinase A activates protein phosphatase 2A by phosphorylation of the B56  subunit

2007 ◽  
Vol 104 (8) ◽  
pp. 2979-2984 ◽  
Author(s):  
J.-H. Ahn ◽  
T. McAvoy ◽  
S. V. Rakhilin ◽  
A. Nishi ◽  
P. Greengard ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Phosphatase 2A ◽  
Kinase A

scholarly journals B56α/Protein Phosphatase 2A Inhibits Adipose Lipolysis in High-Fat Diet-Induced Obese Mice

Endocrinology ◽  
2010 ◽  
Vol 151 (8) ◽  
pp. 3624-3632 ◽  
Author(s):  
Brice P. Kinney ◽  
Liping Qiao ◽  
Justin M. LeVaugh ◽  
Jianhua Shao
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Phosphatase ◽  
High Fat Diet ◽  
Protein Phosphatase 2A ◽  
High Fat ◽  
Protein Levels ◽  
Epididymal Fat ◽  
Phosphatase 2A ◽  
Kinase A

Lipolysis and lipogenesis are two opposite processes that control lipid storage in adipocytes. Impaired adipose lipolysis has been observed in both obese human subjects and animal models. This study investigated the mechanisms underlying impaired adipose lipolysis in a high-fat diet-induced obese (DIO) mouse model. DIO models were created using male C57BL/6 mice. Our results show that β3 adrenergic receptor-specific agonist BRL37344 induced adipose lipolysis was significantly blunted in DIO mice. The levels of Ser660 phosphorylation of hormone-sensitive lipase (HSL) were significantly decreased in the epididymal fat of DIO mice. However, protein levels of HSL, adipose triglyceride lipase and its coactivator comparative gene identification-58 were similar between DIO and control mice. It is known that upon lipolytic hormone stimulation, protein kinase A phosphorylates HSL Ser660 and activates HSL, whereas protein phosphatase 2A (PP2A) dephosphorylates and inactivates HSL. Interestingly, our study shows that high-fat feeding did not alter epididymal fat cAMP and protein kinase A protein levels but significantly increased the expression of the α-isoform of PP2A regulatory subunit B′ (B56α). To study the role of B56α in obesity-associated lipolytic defect, B56α was overexpressed or knocked down by adenovirus-mediated gene transduction in cultured 3T3-L1CARΔ1 adipocytes. Overexpression of B56α significantly decreased HSL Ser660 phosphorylation. In contrast, knocking down B56α increased hormone-stimulated HSL activation and lipolysis in mature 3T3-L1CARΔ1 adipocytes. These results strongly suggest that elevated B56α/PP2A inhibits HSL and lipolysis in white adipose tissue of DIO mice.

scholarly journals Regulation of Organelle Movement in Melanophores by Protein Kinase A (PKA), Protein Kinase C (PKC), and Protein Phosphatase 2A (PP2A)

1998 ◽  
Vol 142 (3) ◽  
pp. 803-813 ◽  
Author(s):  
Amy R. Reilein ◽  
Irina S. Tint ◽  
Natalia I. Peunova ◽  
Grigori N. Enikolopov ◽  
Vladimir I. Gelfand
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Organelle Transport ◽  
Pigment Dispersion ◽  
Kinase C ◽  
Phosphatase 2A ◽  
Kinase A

We used melanophores, cells specialized for regulated organelle transport, to study signaling pathways involved in the regulation of transport. We transfected immortalized Xenopus melanophores with plasmids encoding epitope-tagged inhibitors of protein phosphatases and protein kinases or control plasmids encoding inactive analogues of these inhibitors. Expression of a recombinant inhibitor of protein kinase A (PKA) results in spontaneous pigment aggregation. α-Melanocyte-stimulating hormone (MSH), a stimulus which increases intracellular cAMP, cannot disperse pigment in these cells. However, melanosomes in these cells can be partially dispersed by PMA, an activator of protein kinase C (PKC). When a recombinant inhibitor of PKC is expressed in melanophores, PMA-induced pigment dispersion is inhibited, but not dispersion induced by MSH. We conclude that PKA and PKC activate two different pathways for melanosome dispersion. When melanophores express the small t antigen of SV-40 virus, a specific inhibitor of protein phosphatase 2A (PP2A), aggregation is completely prevented. Conversely, overexpression of PP2A inhibits pigment dispersion by MSH. Inhibitors of protein phosphatase 1 and protein phosphatase 2B (PP2B) do not affect pigment movement. Therefore, melanosome aggregation is mediated by PP2A.

Inhibition of 5‐HT1Areceptor‐dependent cell survival by cAMP/protein kinase A: Role of protein phosphatase 2A and Bax

2008 ◽  
Vol 86 (10) ◽  
pp. 2326-2338 ◽  
Author(s):  
Shu‐chi Hsiung ◽  
Adrianne Tin ◽  
Hadassah Tamir ◽  
Thomas F. Franke ◽  
Kuo‐peing Liu
Keyword(s):  
Protein Kinase ◽  
Cell Survival ◽  
Protein Kinase A ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Phosphatase 2A ◽  
Dependent Cell ◽  
Kinase A

scholarly journals A tightly associated serine/threonine protein kinase regulates phosphoinositide 3-kinase activity.

1993 ◽  
Vol 13 (3) ◽  
pp. 1657-1665 ◽  
Author(s):  
C L Carpenter ◽  
K R Auger ◽  
B C Duckworth ◽  
W M Hou ◽  
B Schaffhausen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Phosphatase ◽  
Kinase Activity ◽  
Protein Phosphatase 2A ◽  
T Antigen ◽  
Serine Kinase ◽  
Phosphatase 2A ◽  
Phosphoinositide 3 Kinase

We identified a serine/threonine protein kinase that is associated with and phosphorylates phosphoinositide 3-kinase (PtdIns 3-kinase). The serine kinase phosphorylates both the 85- and 110-kDa subunits of PtdIns 3-kinase and purifies with it from rat liver and immunoprecipitates with antibodies raised to the 85-kDa subunit. Tryptic phosphopeptide maps indicate that p85 from polyomavirus middle T-transformed cells is phosphorylated in vivo at three sites phosphorylated in vitro by the associated serine kinase. The 85-kDa subunit of PtdIns 3-kinase is phosphorylated in vitro on serine at a stoichiometry of approximately 1 mol of phosphate per mol of p85. This phosphorylation results in a three- to sevenfold decrease in PtdIns 3-kinase activity. Dephosphorylation with protein phosphatase 2A reverses the inhibition. This suggests that the association of protein phosphatase 2A with middle T antigen may function to activate PtdIns 3-kinase.

Nuclear protein phosphatase 2A dephosphorylates protein kinase A-phosphorylated CREB and regulates CREB transcriptional stimulation

1993 ◽  
Vol 13 (5) ◽  
pp. 2822-2834
Author(s):  
B E Wadzinski ◽  
W H Wheat ◽  
S Jaspers ◽  
L F Peruski ◽  
R L Lickteig ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Nuclear Protein ◽  
Dibutyryl Camp ◽  
Nuclear Extracts ◽  
Phosphorylated Creb ◽  
Kinase A

Cyclic AMP (cAMP)-dependent protein kinase A (PKA) stimulates the transcription of many eucaryotic genes by catalyzing the phosphorylation of the cAMP-regulatory element binding protein (CREB). Conversely, the attenuation or inhibition of cAMP-stimulated gene transcription would require the dephosphorylation of CREB by a nuclear protein phosphatase. In HepG2 cells treated with the protein serine/threonine (Ser/Thr) phosphatase inhibitor okadaic acid, dibutyryl-cAMP-stimulated transcription from the phosphoenolpyruvate carboxykinase (PEPCK) promoter was enhanced over the level of PEPCK gene transcription observed in cells treated with dibutyryl-cAMP alone. This process was mediated, at least in part, by a region of the PEPCK promoter that binds CREB. Likewise, okadaic acid prevents the dephosphorylation of PKA-phosphorylated CREB in rat liver nuclear extracts and enhances the ability of PKA to stimulate transcription from the PEPCK promoter in cell-free reactions. The ability of okadaic acid to enhance PKA-stimulated transcription in vitro was entirely dependent on the presence of CREB in the reactions. The phospho-CREB (P-CREB) phosphatase activity present in nuclear extracts coelutes with protein Ser/Thr phosphatase type 2A (PP2A) on Mono Q, amino-hexyl Sepharose, and heparin agarose columns and was chromatographically resolved from nuclear protein Ser/Thr-phosphatase type 1 (PP1). Furthermore, P-CREB phosphatase activity in nuclear extracts was unaffected by the heat-stable protein inhibitor-2, which is a potent and selective inhibitor of PP1. Nuclear PP2A dephosphorylated P-CREB 30-fold more efficiently than did nuclear PP1. Finally, when PKA-phosphorylated CREB was treated with immunopurified PP2A and PP1, the PP2A-treated CREB did not stimulate transcription from the PEPCK promoter in vitro, whereas the PP1-treated CREB retained the ability to stimulate transcription. Nuclear PP2A appears to be the primary phosphatase that dephosphorylates PKA-phosphorylated CREB.

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