Effect of the protein phosphatase inhibitors, okadaic acid and calyculin A, on dexamethasone-mediated inhibition of neutrophil apoptosis

1997 ◽  
Vol 25 (2) ◽  
pp. 246S-246S ◽  
Author(s):  
JOANNE M. COUSIN ◽  
CHRISTOPHER HASLETT ◽  
ADRIANO G. ROSSI
Keyword(s):  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Neutrophil Apoptosis ◽  
Calyculin A ◽  
Phosphatase Inhibitors ◽  
Protein Phosphatase Inhibitors

Regulation of mammalian ribonucleotide reductase by the tumor promoters and protein phosphatase inhibitors okadaic acid and calyculin A

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1081-1087 ◽  
Author(s):  
Robert A. R. Hurta ◽  
Jim A. Wright
Keyword(s):  
Okadaic Acid ◽  
Ribonucleotide Reductase ◽  
Protein Phosphatase ◽  
Reductase Activity ◽  
Tumor Promoter ◽  
Calyculin A ◽  
Tumor Promoters ◽  
Phosphatase Inhibitors ◽  
Protein Phosphatase Inhibitors ◽  
Ribonucleotide Reductase Activity

A rapid elevation of ribonucleotide reductase activity was observed with BALB c/3T3 fibroblasts treated with 10 nM okadaic acid, a nonphorbol ester tumor promoter and protein phosphatase inhibitor. Northern blot analysis of the two components of ribonucleotide reductase (R1 and R2) showed a marked elevation of R1 and R2 mRNA expression. Western blot analysis with R1 and R2 specific monoclonal antibodies indicated that the increase in ribonucleotide reductase activity was primarily due to the elevation of the R2 rather than the R1 protein during treatment with okadaic acid. The okadaic acid induced elevations in R1 and R2 message levels occurred without a detectable change in the proportion of cells in S phase and were blocked by treatment of cells with actinomycin D, indicating the importance of the reductase transcriptional process in responding to the action of okadaic acid. Furthermore, down-regulation of protein kinase C with 12-O-tetradecanoylphorbol-13-acetate pretreatment abrogated the okadaic acid mediated elevation of ribonucleotide reductase mRNAs, consistent with the involvement of this signal pathway in the regulation of ribonucleotide reductase and the effects of okadaic acid. Treatment of cells with 2.5 nM calyculin A, another non-phorbol ester tumor promoter and protein phosphatase inhibitor, resulted in a rapid elevation of both R1 and R2 mRNA levels within 10 min of treatment. This first demonstration that the non-phorbol ester tumor promoters and protein phosphatase inhibitors can cause rapid alterations in ribonucleotide reductase gene expression suggests that (i) ribonucleotide reductase, particularly the R2 component, plays a fundamental role in the critical early events involved in the process of tumor promotion, and (ii) illustrates a role for cellular protein phosphatases in the regulation of ribonucleotide reductase and, through this process, the regulation of DNA synthesis.Key words: ribonucleotide reductase, DNA synthesis, okadaic acid, calyculin A, tumor promoter, protein phosphatase.

scholarly journals Effects of the Protein Phosphatase Inhibitors Okadaic Acid and Calyculin A on Insulin Release from Rat Pancreatic Islets.

1992 ◽  
Vol 39 (3) ◽  
pp. 325-329 ◽  
Author(s):  
TATSUO TAMAGAWA ◽  
AKIHISA IGUCHI ◽  
KAZUMASA UEMURA ◽  
HISAYUKI MIURA ◽  
KATSUNORI NONOGAKI ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Insulin Release ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Calyculin A ◽  
Phosphatase Inhibitors ◽  
Rat Pancreatic Islets ◽  
Protein Phosphatase Inhibitors

scholarly journals Colorimetric Immuno-Protein Phosphatase Inhibition Assay for Specific Detection of Microcystins and Nodularins of Cyanobacteria

2001 ◽  
Vol 67 (2) ◽  
pp. 904-909 ◽  
Author(s):  
James S. Metcalf ◽  
Steven G. Bell ◽  
Geoffrey A. Codd
Keyword(s):  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Cyclic Peptide ◽  
Calyculin A ◽  
Inhibition Assay ◽  
Specific Detection ◽  
Phosphatase Inhibitors ◽  
Protein Phosphatase Inhibitors ◽  
Protein Phosphatase Inhibition ◽  
Phosphatase Inhibition

ABSTRACT A novel immunoassay was developed for specific detection of cyanobacterial cyclic peptide hepatotoxins which inhibit protein phosphatases. Immunoassay methods currently used for microcystin and nodularin detection and analysis do not provide information on the toxicity of microcystin and/or nodularin variants. Furthermore, protein phosphatase inhibition-based assays for these toxins are not specific and respond to other environmental protein phosphatase inhibitors, such as okadaic acid, calyculin A, and tautomycin. We addressed the problem of specificity in the analysis of protein phosphatase inhibitors by combining immunoassay-based detection of the toxins with a colorimetric protein phosphatase inhibition system in a single assay, designated the colorimetric immuno-protein phosphatase inhibition assay (CIPPIA). Polyclonal antibodies against microcystin-LR were used in conjunction with protein phosphatase inhibition, which enabled seven purified microcystin variants (microcystin-LR, -D-Asp3-RR, -LA, -LF, -LY, -LW, and -YR) and nodularin to be distinguished from okadaic acid, calyculin A, and tautomycin. A range of microcystin- and nodularin-containing laboratory strains and environmental samples of cyanobacteria were assayed by CIPPIA, and the results showed good correlation (R 2 = 0.94, P< 0.00001) with the results of high-performance liquid chromatography with diode array detection for toxin analysis. The CIPPIA procedure combines ease of use and detection of low concentrations with toxicity assessment and specificity for analysis of microcystins and nodularins.

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