Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Compared to the wild-type parental line of S49 mouse lymphoma cells, intact cells of a mutant line (kin.A) are 10-fold less sensititive to biologic effects of exogenous cyclic adenosine 3':5'-monophophosphate (cAMP), such as induction of cAMP phosphodiesterase, cell cycle-specific growth inhibition, and cytolysis. The cAMP-dependent protein kinase (ATP:protein phosphotransferase; EC 2.7.1.37) activity of kin.A cells exhibits an apparent Ka for activation by cAMP 10-fold greater than that of wild type, and is much more resistant to inactivation by heat. These differences between the wild-type and mutant enzymes persist through a high degree of purification, suggesting a structural alteration in the kin.A holoenzyme. Heterologous reconstitution experiments, using separated R and C subunits of the wild-type and kin.A cAMP-dependent kinases, show that the altered cAMP affinity and thermolability are conferred by the R component of the kin.A enzyme. These results are most consistent with a structural mutation in the kin.A gene coding for the R subunit of cAMP-dependent protein kinase. Evidence for a structural mutation helps to define one mechanism of heritable variation in cultured somatic cells. The phenotype produced by the kin.A structural mutation also greatly strengthens the conslusion that cAMP-dependent protein kinase is essential for cAMP regulation of growth and enzyme induction in intact S49 cells.
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PMID:A structural gene mutation affecting the regulatory subunit of cyclic AMP-dependent protein kinase in mouse lymphoma cells. 17 91

Experiments with cold exposure confirmed previous studies indicating that the endogenous protein acitvator of phosphodiesterase (PDEA) isolated by Cheung participates in the in vivo regulation of 3':5'-cyclic adenosine monophosphate (cAMP) in adrenal medulla. This activator of cAMP phosphodiesterase (PDE) (3':5'-cyclic-AMP 5'-nucleotidohydrolase, EC 3.1.4.17) is present in the particulate as well as the soluble fractions of rat brain. It was found that a purified cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37), in the presence of ATP and cAMP, stimulates 3-fold the release of PDEA from the particulate fraction of rat brain and adrenal medulla. The substrate for this phosphorylation could be either a membrane protein that binds PDEA or PDEA itself. In vivo evidence, however, obtained by injecting rats intraventricularly with [gamma-32P]ATP, indicates that the PDEA does not contain radioactive phosphate in its structure. Also, PDEA could not be phosphorylated by protein kinase in vitro. The following mechanism is postulated: when the intracellular content of cAMP increases it activates a protein kinase which phosphorylates a PDEA-binding membrane protein and releases PDEA. In turn this binds to activator-deficient high Km PDE and decreases its Km to facilitate the hydrolysis of the increased concentration of cAMP.
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PMID:Regulation of transsynaptically elicited increase of 3':5'-cyclic AMP by endogenous phosphodiesterase activator. 17 3

The ability of cyclic AMP to inhibit growth, cause cytolysis and induce synthesis of cyclic AMP-phosphodiesterase in S49.1 mouse lymphoma cells is deficient in cells selected on the basis of their resistance to killing by 2 mM dibutyryl cyclic AMP. The properties of the cyclic AMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) in the cyclic AMP-sensitive (S) and cyclic AMP-resistant (R) lymphoma cells were comparatively studied. The cyclic AMP-dependent protein kinase activity or R cells cytosol exhibits an apparent Ka for activation by cyclic AMP 100-fold greater than that of the enzyme from the parental S cells. The free regulatory and catalytic subunits from both S and R kinase are thermolabile, when associated in the holoenzyme the two subunits are more stable to heat inactivation in R kinase than in S kinase. The increased heat stability of R kinase is observed however only for the enzyme in which the catalytic and cyclic AMP-binding activities are expressed at high cyclic AMP concentrations (10(-5)--10(-4) M), the activities expressed at low cyclic AMP concentrations (10(-9)--10(-6) M) being thermolabile. The regulatory subunit of S kinase can be stabilized against heat inactivation by cyclic AMP binding both at 2-10(-7) and 10(-5) M cyclic AMP concentrations. In contrast, the regulatory subunit-cyclic AMP complex from R kinase is stable to heat inactivation only when formed in the presence of high cyclic AMP concentrations (10(-5)M). The findings indicate that the transition from a cyclic AMP-sensitive to a cyclic AMP-resistant lymphoma cell phenotype is related to a structural alteration in the regulatory subunit of the cyclic AMP-dependent protein kinase which has affected the protein's affinity for cyclic AMP and its interaction with the catalytic subunit.
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PMID:Altered regulation of cyclic AMP-dependent protein kinase in a mouse lymphoma cell line. 19 71

2-Methoxyethanol (ME) and its metabolite, methoxyacetic acid (MAA), produce testicular lesions characterized by pachytene spermatocyte degeneration. To understand the molecular basis of this action on meiotic prophase cells, mRNA differential display was used to identify gene expression changes in control and treated cells. When pachytene spermatocytes were cultured with 5 mM ME or 5 mM MAA for 24 h, two complementary DNAs (cDNAs), of 557 nucleotides (clone 5) and 388 nucleotides (clone 6), were up-regulated; and a cDNA of 648 nucleotides (clone 1) was down-regulated. The altered expression pattern shown by differential display was confirmed by Northern blotting. Sequence analyses indicate that clones 1 and 6 have 83% and 79% homology at the nucleotide level to a polo-like kinase and a thiol-specific antioxidant, respectively. Clone 5 shows no homology to any known gene in the database. Messenger RNAs (mRNAs) encoding the thiol-specific antioxidant and clone 5 are up-regulated within 30 min of the addition of MAA, whereas the polo-like kinase mRNA decreased to undetectable levels after 6 h. Changes in Sertoli cell gene expression were also detected when Sertoli cells were cultured with 5 mM ME or MAA for 24 h. Two cDNAs, of 367 nucleotides (clone 2) and 676 nucleotides (clone 3), were up-regulated; and a cDNA of 538 nucleotides (clone 4) was down-regulated. Homology searches revealed that clones 3 and 4 have 90 and 91% homology at the nucleotide level to an oxidative stress protein and a phosphodiesterase (PDE), respectively. Northern blotting confirmed the differential display expression pattern for the PDE and oxidative stress protein. mRNAs for the latter were induced within 30 min, and PDE mRNAs were down-regulated within one h, after the addition of MAA. To determine whether the changes in gene expression seen with cells in culture also occur in vivo, rats were given a single oral dose of 250 mg/kg ME or MAA. After 24 h, total testis RNAs from control and treated rats were purified and hybridized. The expression patterns seen in vivo for the differentially expressed cDNAs were identical to those seen in vitro. We conclude that, although pachytene spermatocytes seem to be selectively affected by ME and MAA, changes in gene expression are also detected in Sertoli cells, suggesting that the action(s) of ME or MAA on pachytene spermatocytes could be mediated through Sertoli cells.
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PMID:Rat pachytene spermatocytes down-regulate a polo-like kinase and up-regulate a thiol-specific antioxidant protein, whereas sertoli cells down-regulate a phosphodiesterase and up-regulate an oxidative stress protein after exposure to methoxyethanol and methoxyacetic acid. 968 1