Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The binding of cyclic AMP to the proximal tubule luminal (brush border) membrane isolated from the rabbit renal cortex was studied. The rate of binding was dependent on temperature; at 37 degrees equilibrium was attained in 45 min, whereas at 0 degrees 120 min was required. The final levels of binding were identical. The binding of 3H-cyclic AMP was reversed by dilution or addition of unlabeled cyclic nucleotide. Debinding was markedly temperature sensitive. Binding was only partially saturable with respect to cyclic AMP concentration, apparently with more than one binding site. The cyclic AMP bound to the membrane was recovered unchanged. When bound to the membrane cyclic AMP was resistant to hydrolysis by endogenous membrane or exogenously added phosphodiesterase. The binding to the membranes was relatively specific for cyclic AMP, although other cyclic purine nucleotides inhibited, cyclic IMP greater than dibutyryl cyclic AMP greater than cyclic GMP. The renal membranes did bind cyclic GMP, but this binding was relatively non-specific. Hormones and drugs, that mediate cyclic AMP generation or renal function, as well as other compounds common to the proximal tubule were without significant effect on cyclic AMP binding. Binding was inhibited by sulfhydryl reacting agents and this inhibition could be blocked and partially reversed by mercaptoethanol.
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PMID:The binding of cyclic AMP to renal brush border membranes. 17 56

Previous findings suggest that alkaline phosphatase (Alk Pase) may be involved in phosphate transport. Since phosphate reabsorption is enhanced in the kidney and duodenum of animals stabilized on a low-phosphorus diet (LPD), Alk Pase was measured in the kidney, small intestine, and other tissues in LPD rats. In particulate fractions from the renal cortex, intestine, renal medulla, liver, and heart ventricle from LPD rats the activity of Alk Pase was significantly increased but the activities of other plasma membrane enzymes were not different between control and LPD groups. The increased Alk Pase in the renal cortex was localized to the brush border of the proximal tubule histochemically and by measurement of Alk Pase in brush-border preparations. Also in the renal cortex, typical enzymes associated with mitochondria, lysosomes, and cytosol were unchanged with the exception of cytosolic adenosine 3',5' cyclic-monophosphate phosphodiesterase, which was increased in LPD rats. Alk Pase in the renal cortex and intestine may play a role in the enhanced phosphate reabsorption in LPD animals.
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PMID:Alkaline phosphatase in adaptation to low dietary phosphate intake. 49 49

During placental development cytotrophoblast stem cells fuse to form the syncytiotrophoblast, a multinucleate cytoplasm with a brush border in contact with the maternal blood. Biochemical differentiation including the expression of placental-specific proteins and hormones accompanies this maturation. However, the biochemical mechanisms responsible for these events are unknown. We have defined a system in which single cytotrophoblast-like cells of the human choriocarcinoma (BeWo) cell line undergo fusion and extensive morphological differentiation following their treatment with effectors of cyclic AMP metabolism. Forskolin incubation caused a dose-dependent increase in intracellular and secreted cyclic AMP and a coordinate fusion of cells which yielded syncytia containing hundreds of nuclei per cytoplasm and a mature dense "placental-like" brush border. These fused cells also synthesized and secreted large amounts of both subunits of chorionic gonadotropin. However, they continued to synthesize several other placenta-specific proteins--placental-like alkaline phosphatase, placental lactogen, and SP1--at rates similar to those in control cells. Other reported effectors of cyclic AMP metabolism also induced cell fusion, although theophylline, an inhibitor of phosphodiesterase, induced fusion by a cyclic AMP-independent mechanism. Additionally, unlike the case with forskolin, treatment of BeWo cells with theophylline did not induce other morphological features of mature syncytiotrophoblasts. Thus, this system will allow one to examine the biochemical mechanism of placental cell fusion in the absence of other variables of cell differentiation.
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PMID:Modulators of cyclic AMP metabolism induce syncytiotrophoblast formation in vitro. 215 59

The phosphodiesterase-inhibitor 3-isobutyl-1-methylxanthine (IBMX) was able to elevate rat small intestinal cyclic AMP levels to 300% of basal values. Active jejunal D-glucose transport was enhanced parallel to the rise of intracellular cyclic AMP levels to 140% of control values at 100 mumol/l IBMX. Transport parameters, as determined in a three compartment model in vitro using a dual label method, indicate increased 'uphill' glucose transport at the site of the brush border membrane, higher intracellular accumulation of the sugar, with unchanged passive permeabilities. Phlorizin-inhibited D-glucose transport and L-glucose transfer in the rat were not affected by the persisting cyclic AMP elevation produced by IBMX. Stimulating effects could also be demonstrated with D-galactose as a substrate. IBMX 100 mumol/l also increased active D-glucose as well as 3-O-methylglucose transport in mouse jejunum. Stimulatory effects on intestinal hexose transport and mucosal cyclic AMP levels were also found with the adenylate-cyclase activator forskolin. In the present study, forskolin effects on jejunal mucosal cyclic AMP levels were enhanced in the presence of 100 mumol/l IBMX, resulting in a 20-fold increase compared to controls at 20 mumol/l forskolin. The concentration response for the effect of forskolin in the presence of 100 mumol/l IBMX on D-glucose transport did not produce a significant increase compared to transport stimulation with IBMX alone. At higher concentrations of forskolin however, glucose transport decreased to levels well below the IBMX controls. The elevation of cellular cyclic AMP levels had no effects on passive permeability.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Response of rat small intestinal active aldohexose transport to elevation of mucosal cyclic AMP by forskolin and 3-isobutyl-1-methylxanthine in vitro. 241 72

Six different monoclonal antibodies were generated after immunization of mice with a partially purified enzyme preparation of rat liver, containing nucleotide-sugar hydrolase (NSH) I and II. These enzymes are also known under the names phosphodiesterase I and CMP-sialic acid hydrolase respectively [11]. In the enzyme-immunoassay the antibodies directed against NSH I displayed some cross-reactivity with the enzyme preparation of NSH II, and to a much lower extent the reverse was also true. Two antibodies, C and D highly reactive with NSH II and NSH I respectively, were used for immunocytochemical studies on sections of various rat tissues, which were known to contain high activities of both enzymes. Both antibodies were shown to be highly specific domain markers for different sides of the various cells. Antibody C was bound exclusively to the sinusoidal side of liver hepatocytes and to the basal side of cells from kidney tubule and epididymis. For antibody D the binding pattern was completely different, showing exclusive binding to the canalicular side of the hepatocytes and to the brush border membranes of kidney tubule cells, whereas in epididymis only binding to connective tissues was observed. Our studies clearly demonstrate, at least for liver and kidney, that NSH I and II are located at different cellular sides and that the monoclonal antibodies C and D can be used as domain markers for basal and apical sides of these cells respectively.
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PMID:Detection of different cellular sides in rat liver and kidney by two monoclonal antibodies raised against the nucleotide-sugar hydrolyzing enzymes phosphodiesterase I and CMP-sialic acid hydrolase. 298 96

Purified brush border membrane of Cotugnia digonopora showed the presence of a number of phosphohydrolases. Among these, alkaline phosphatase was extremely active. Other enzymes such as glucose-6-phosphatase, fructose-1,6-diphosphatase, cAMP-phosphodiesterase, 5'-nucleotidase and adenosine-triphosphatase were also active. Observations were made on the activities of various ATPases; whereas the enzyme was activated by Ca++ and Mg++ in an additive manner, its sensitivity to ouabain was negligible. Furthermore, in the presence of EDTA the enzyme activity was quite significant. The treatment of isolated brush border membrane with mebendazole, niclosamide and praziquantel in vitro did not alter the activity of these enzymes. However, treatment of intact worms drastically affected the integrity of the membrane.
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PMID:Enzymes of isolated brush border membrane of Cotugnia digonopora, and their insensitivity to anthelmintics in vitro. 299 11

Phosphodiesterase I (PDE I) is an exonuclease capable of hydrolyzing a variety of phosphate ester and pyrophosphate bonds. Cell fractionation and histochemical studies in animal tissues have localized PDE I in the plasma membrane of various epithelia. This suggests a role for the enzyme in active transport. Distribution of PDE I in human tissues has not previously been studied. We have produced a polyclonal antiserum to bovine intestinal PDE I and have demonstrated crossreactivity with the human intestinal enzyme. This polyclonal antiserum was used in PAP immunocytochemistry to localize immunoreactive PDE I in a variety of human tissues. Localization was prominent in the gastrointestinal tract, including the cytoplasm of gastric mucosa parietal cells, cytoplasm of surface epithelium and isolated crypt cells in small intestine, and the colonic epithelial cytoplasm and brush border. Parotid gland acinar cells and scattered ductal cells showed positive cytoplasmic staining. Acinar and scattered pancreatic islet cells contained immunoreactive PDE I, as did Kupffer cells of the liver sinusoids. Immunoreactive PDE I was found in all vascular endothelia. The epithelium of the urinary tract showed extensive immunoreactivity. This included the distal convoluted and collecting tubules of the kidney, and ureteral and bladder urothelium. In previous histochemical studies of animal tissues, no evidence of PDE I activity was noted in male or female reproductive tract. In this study, immunoreactive PDE I was localized to human Sertoli cells and to basal epithelium of the epididymis and prostate acini. Fallopian tube epithelium of female reproductive tract also demonstrated immunoreactive PDI I, as did several cell types in term placenta. Our immunocytochemical results with human tissues differ significantly from previous histochemical studies in animal tissues, principally in the genitourinary system. This may be due in part to the different detection systems employed as well as the higher sensitivity of the immunoperoxidase technique. This underscores the importance of adjunct techniques in tissue surveys. The widespread epithelial distribution of immunoreactive PDE I detected by this polyclonal antibody implies an integral role in cell function, probably in active transport.
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PMID:Distribution of phosphodiesterase I in normal human tissues. 302 90

The effects of the phenothiazine, Stelazine, on Hymenolepis diminuta were investigated. The cestode was incubated for 10 min at 37 degrees C with 1 mM trifluoperazine, in the presence and absence of Ca2+. Assay of brush border enzymes showed that drug treatment lowered the activities of alkaline phosphatase, Ca2+-ATP'ase, 5'-nucleotidase and type 1 phosphodiesterase. This occurred in parallel with a significant reduction in tegumental protein. Under these conditions gross changes in ultrastructural appearance and cellular organization were observed. There was a lack of ordered microtriches and the distal cytoplasm was absent. Glycogen granules were scattered throughout the cytoplasm within the subtegumental layer. The connective tissue also appeared to be in some disarray. The effects of Stelazine appeared to be dependent on time and were significantly increased when Ca2+ was included in the incubation medium. Incubation with the less hydrophobic phenothiazine trifluoperazine sulphoxide had minimal effect on the integrity of the cestode. The results reported here support the premise that certain phenothiazines may be considered as potential cestocidal agents.
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PMID:Biochemical and ultrastructural investigation of the effect of Stelazine (trifluoperazine) on Hymenolepis diminuta (Cestoda). 302 50

Ectoenzyme release from porcine intestinal brush border membranes by phosphatidylinositol-specific phospholipase C of Bacillus thuringiensis was studied. Alkaline phosphodiesterase I, alkaline phosphatase and 5'-nucleotidase were released from both slices and brush border membranes. The pattern of alkaline phosphodiesterase I release was the same as that of alkaline phosphatase. The release of alkaline phosphodiesterase I induced by phospholipase C was dependent on, or proportional to, the reaction time and the concentration of phospholipase C. The Arrhenius plot for phosphodiesterase I release showed a single break at 30 degrees C for brush border membranes. Only 40% of alkaline phosphodiesterase I present in the brush border membranes were solubilized by phosphatidylinositol-specific phospholipase C treatment. The data indicate the presence of two forms of phosphodiesterase I, which are different in their sensitivity to phospholipase C. The released alkaline phosphodiesterase I had a molecular weight of 240,000 and was activated by Mg2+ and Ca2+, but strongly inhibited by EDTA.
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PMID:Alkaline phosphodiesterase I release from eucaryotic plasma membranes by phosphatidylinositol-specific phospholipase C. II. The release from brush border membranes of porcine intestine. 302

Several hydrolase activities characteristic of the apical brush border membrane of renal proximal tubule, leucine aminopeptidase, gamma-glutamyl transpeptidase, alkaline phosphatase, maltase, and trehalase, were identified in cultures of the LLC-PK1 kidney epithelial cell line. A coordinate increase in activities of these enzymes was observed upon development of a confluent cell density and functional membrane polarization. Further large progressive increases in individual hydrolase activities were induced after the addition of compounds known as differentiation inducers. Hexamethylene bisacetamide preferentially induced increased trehalase and maltase activities. Induced trehalase activity exhibited an increased Vmax but a similar Km compared with activity in control extracts. Induction required protein synthesis and was dependent on inducer concentration and exposure time. Treatment of confluent cultures with N,N'-dimethylformamide triggered an induction of maltase, trehalase, alkaline phosphatase, and gamma-glutamyl transpeptidase activities, whereas dimethylsulfoxide induced trehalase and gamma-glutamyl transpeptidase activities. Increased leucine aminopeptidase and maltase activities were observed after addition of the phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine. Induction of trehalase activity by N,N'-dimethylformamide was reversible over a 4-day period after removal of inducer, but effects of hexamethylene bisacetamide were irreversible. These results suggest that the LLC-PK1 cell line reproducibly develops differentiation-specific characteristics under defined conditions in cell culture, which can be individually modulated by chemicals known as inducers of cell differentiation.
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PMID:Induction of microvillar hydrolase activities by cell density and exogenous differentiation inducers in an established kidney epithelial cell line (LLC-PK1). 609 Apr 80


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