Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Inhibition of foetal pulmonary choline-phosphate cytidylyltransferase under conditions favouring protein phosphorylation.

ABSTRACT: Choline-phosphate cytidylyltransferase (EC 2.7.7.15) activity from 25- and 29-day-foetal rabbit lungs was inhibited in both the cytosolic and the microsomal fractions by preincubation with MgATP. The inhibition of the cytosolic enzyme was greater when measured with added phosphatidylglycerol (PG) than without (78-89% versus 50-55%), whereas the inhibition of the microsomal enzyme did not exhibit this distinction (66-72% versus 60-70%). When preincubated with the buffer alone, the cytosolic enzyme was activated to a greater extent by added PG than was the microsomal enzyme (13-14-fold versus 2-3-fold). However, after preincubation with MgATP, the cytosolic enzyme was activated to a smaller extent by added PG (3-6-fold). The inhibition of the enzyme by MgATP required a preincubation and was absent when ADP or AMP was substituted for ATP. Moreover, ATP analogues such as adenosine 5'-[beta, gamma-methylene]triphosphate and adenosine 5'-[gamma-thio]triphosphate also failed to inhibit the enzyme when substituted for ATP in the preincubation. The inhibition by MgATP was not affected by including cyclic AMP in the preincubation, but Ca2+ ions alone or plus diacylglycerol in the preincubation increased the inhibition slightly. The inhibition was abolished by including an inhibitor of cyclic-AMP-dependent protein kinase in the preincubation. These observations, taken collectively, point to the inhibition of foetal pulmonary cytidylyltransferase through the phosphorylation of a protein and suggest that this key enzyme in lung surfactant production may be regulated through this mechanism.

SUBMITTER: Radika K

PROVIDER: S-EPMC1152958 | biostudies-other | 1985 Dec

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

The control of CTP:choline-phosphate cytidylyltransferase activity in pea (Pisum sativum L.).

Project description:Several possible control mechanisms for CTP:choline-phosphate cytidylyltransferase (EC 2.7.7.15) activity in pea (Pisum sativum L.) stems were investigated. Indol-3-ylacetic acid (IAA) treatment of the pea stems decreased total cytidylyltransferase activity but did not affect its subcellular distribution. Oleate (2 mM) caused some stimulation of enzyme activity by release of activity from the microsomal fraction into the cytosol, but neither phosphatidylglycerol nor monoacyl phosphatidylethanolamine had an effect on activity or subcellular distribution. A decrease in soluble cytidylyltransferase protein concentrations was found in IAA-treated pea stems, but this was not sufficient to account for all of the decrease in cytidylyltransferase activity. A 50% inhibition of enzyme activity could be obtained with 0.2 mM-CMP, which indicated possible allosteric regulation. Similar inhibition was obtained with 1.5 mM-ATP, but other nucleotides had no effect. The cytidylyltransferase enzyme protein was not directly phosphorylated, and the inhibition with 1.5 mM-ATP occurred with the purified enzyme, thus excluding an obligatory mediation via a modulator protein. The results indicate that the cytosolic form of cytidylyltransferase is the most important in pea stem tissue and that the decrease in cytidylyltransferase activity in IAA-treated material appears to be brought about by several methods.

| S-EPMC1147495 | biostudies-other

Maternal administration of dexamethasone stimulates choline-phosphate cytidylyltransferase in fetal type II cells.

Project description:Administration of dexamethasone to pregnant rats at 19 days gestation increased phosphatidylcholine synthesis (45%) from radioactive choline in type II cells. This enhanced synthesis of phosphatidylcholine was accompanied by an increased conversion of choline phosphate into CDP-choline. Similar results were obtained by incubating organotypic cultures of 19-day-fetal rat lung with cortisol. The increased conversion of choline phosphate into CDP-choline correlated with an enhanced choline-phosphate cytidylyltransferase activity (31% after dexamethasone treatment; 47% after cortisol exposure) in the cell homogenates. A similar increase (26% after dexamethasone treatment; 39% after cortisol exposure) was found in the microsomal-associated enzyme. No differences in cytosolic enzyme activity were observed. The specific activity of the microsomal enzyme was 3-4 times that of the cytosolic enzyme. Most of the enzyme activity was located in the microsomal fraction (58-65%). The treatments had no effect on the total amount of enzyme recovered from the cell homogenates. These results, taken collectively, are interpreted to indicate that the active form of cytidylyltransferase in type II cells is the membrane-bound enzyme and that cytidylyltransferase activation in type II cells from fetal rat lung after maternal glucocorticoid administration occurs by binding of inactive cytosolic enzyme to endoplasmic reticulum.

| S-EPMC1147555 | biostudies-other

ADAM15 protein amplifies focal adhesion kinase phosphorylation under genotoxic stress conditions.

Project description:ADAM15, a disintegrin and metalloproteinase, is capable of counteracting genotoxic stress-induced apoptosis by the suppression of caspase-3 activation. A cell line expressing the membrane-bound ADAM15 without its cytoplasmic tail, however, lost this anti-apoptotic property, suggesting a crucial role of the intracellular domain as a scaffold for recruitment of survival signal-transducing kinases. Accordingly, an enhanced phosphorylation of FAK at Tyr-397, Tyr-576, and Tyr-861 was detected upon genotoxic stress by camptothecin in ADAM15-transfected T/C28a4 cells, but not in transfectants expressing an ADAM15 mutant without the cytoplasmic tail. Accordingly, a specific binding of the cytoplasmic ADAM15 domain to the C terminus of FAK could be shown by mammalian two-hybrid, pulldown, and far Western studies. In cells expressing full-length ADAM15, a concomitant activation of Src at Tyr-416 was detected upon camptothecin exposure. Cells transfected with a chimeric construct consisting of the extracellular IL-2 receptor α-chain and the cytoplasmic ADAM15 domain were IL-2-stimulated to prove that the ADAM15 tail can transduce a percepted extracellular signal to enhance FAK and Src phosphorylation. Our studies further demonstrate Src binding to FAK but not a direct Src interaction with ADAM15, suggesting FAK as a critical intracellular adaptor for ADAM15-dependent enhancement of FAK/Src activation. Moreover, the apoptosis induction elicited by specific inhibitors (PP2, FAK 14 inhibitor) of FAK/Src signaling was significantly reduced by ADAM15 expression. The newly uncovered counter-regulatory response to genotoxic stress in a chondrocytic survival pathway is potentially also relevant to apoptosis resistance in neoplastic growth.

| S-EPMC3375543 | biostudies-literature

Phosphorylation of Human Choline Kinase Beta by Protein Kinase A: Its Impact on Activity and Inhibition.

Project description:Choline kinase beta (CK?) is one of the CK isozymes involved in the biosynthesis of phosphatidylcholine. CK? is important for normal mitochondrial function and muscle development as the lack of the ck? gene in human and mice results in the development of muscular dystrophy. In contrast, CK? is implicated in tumorigenesis and has been extensively studied as an anticancer target. Phosphorylation of human CK? was found to regulate the enzyme's activity and its subcellular location. This study provides evidence for CK? phosphorylation by protein kinase A (PKA). In vitro phosphorylation of CK? by PKA was first detected by phosphoprotein staining, as well as by in-gel kinase assays. The phosphorylating kinase was identified as PKA by Western blotting. CK? phosphorylation by MCF-7 cell lysate was inhibited by a PKA-specific inhibitor peptide, and the intracellular phosphorylation of CK? was shown to be regulated by the level of cyclic adenosine monophosphate (cAMP), a PKA activator. Phosphorylation sites were located on CK? residues serine-39 and serine-40 as determined by mass spectrometry and site-directed mutagenesis. Phosphorylation increased the catalytic efficiencies for the substrates choline and ATP about 2-fold, without affecting ethanolamine phosphorylation, and the S39D/S40D CK? phosphorylation mimic behaved kinetically very similar. Remarkably, phosphorylation drastically increased the sensitivity of CK? to hemicholinium-3 (HC-3) inhibition by about 30-fold. These findings suggest that CK?, in concert with CK?, and depending on its phosphorylation status, might play a critical role as a druggable target in carcinogenesis.

| S-EPMC4858151 | biostudies-literature

Isoform-specific and protein kinase C-mediated regulation of CTP:phosphoethanolamine cytidylyltransferase phosphorylation.

Project description:CTP:phosphoethanolamine cytidylyltransferase (Pcyt2) is the main regulatory enzyme for de novo biosynthesis of phosphatidylethanolamine by the CDP-ethanolamine pathway. There are two isoforms of Pcyt2, -? and -?; however, very little is known about their specific roles in this important metabolic pathway. We previously demonstrated increased phosphatidylethanolamine biosynthesis subsequent to elevated activity and phosphorylation of Pcyt2? and -? in MCF-7 breast cancer cells grown under conditions of serum deficiency. Mass spectroscopy analyses of Pcyt2 provided evidence for isoform-specific as well as shared phosphorylations. Pcyt2? was specifically phosphorylated at the end of the first cytidylyltransferase domain. Pcyt2? was phosphorylated within the ?-specific motif that is spliced out in Pcyt2? and on two PKC consensus serine residues, Ser-215 and Ser-223. Single and double mutations of PKC consensus sites reduced Pcyt2? phosphorylation, activity, and phosphatidylethanolamine synthesis by 50-90%. The phosphorylation and activity of endogenous Pcyt2 were dramatically increased with phorbol esters and reduced by specific PKC inhibitors. In vitro translated Pcyt2? was phosphorylated by PKC?, PKC?I, and PKC?II. Pcyt2? Ser-215 was also directly phosphorylated with PKC?. Mapping of the Pcyt2?- and -?-phosphorylated sites to the solved structure of a human Pcyt2? showed that they clustered within and flanking the central linker region that connects the two catalytic domains and is a novel regulatory segment not present in other cytidylyltransferases. This study is the first to demonstrate differences in phosphorylation between Pcyt2 isoforms and to uncover the role of the PKC-regulated phosphorylation.

| S-EPMC3979399 | biostudies-literature

Choline dihydrogen phosphate.

Project description:In the cystal structure of the title compound, (2-hy-droxy-ethyl)trimethylammonium dihydrogen phosphate, C(5)H(14)NO(+)·H(2)PO(4) (-), two anions create dimeric structures via two O-H⋯O hydrogen bonds. The hydrogen-bonded dimers are connected by another O-H⋯O hydrogen bond with the hydroxyl groups of the cations, constructing a columner structure along the a axis. A number of C-H⋯O interactions are also present.

| S-EPMC2969078 | biostudies-literature

N-[2-bromocinnamyl(amino)ethyl]-5-isoquinolinesulphonamide (H-89) inhibits incorporation of choline into phosphatidylcholine via inhibition of choline kinase and has no effect on the phosphorylation of CTP:phosphocholine cytidylyltransferase.

Project description:We have shown previously that N-[2-bromocinnamyl(amino)-ethyl]-5-isoquinolinesulphonamide (H-89), a selective inhibitor of cyclic-AMP-dependent protein kinase (PKA), inhibits phosphatidylcholine biosynthesis in HeLa cells. In the present study, we elucidated the mechanism underlying the described inhibition. Treatment of cells with 10 microM H-89 had no effect on the phosphorylation of CTP:phosphocholine cytidylyltransferase. However, H-89 slightly affected the distribution of cytidylyltransferase between cytosol and membranes, but the cellular 1,2-diacylglycerol content was not influenced. Furthermore, pulse-chase experiments revealed that H-89 did not affect cytidylyltransferase activity. Instead, H-89 inhibited choline kinase, the enzyme catalysing the first step in the CDP-choline pathway. In the presence of 10 microM H-89, choline kinase activity was inhibited by 36 +/- 7.6% in vitro. Additionally, the phosphorylation of choline to phosphocholine was inhibited by 30 +/- 3% in cell-culture experiments. This inhibitory effect could be partly prevented by simultaneous addition of 10 microM forskolin, indicating that choline kinase is regulated in part by PKA activity.

| S-EPMC1137816 | biostudies-other

Regulation of calcium phosphate formation by amelogenins under physiological conditions.

Project description:Amelogenin is essential for proper enamel formation. The present in vitro study extends our previous work at low (10 mM) ionic strength (IS) by examining the effect of amelogenin on mineralization under higher (162 mM) IS conditions found in developing enamel. Full-length phosphorylated (P173) and non-phosphorylated (rP172) amelogenins were examined, along with P148 and rP147 that lack the hydrophilic C-terminus. Calcium phosphate formation was assessed by pH change, while the minerals formed were characterized using transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy. Amelogenin self-assembly was also studied using dynamic light scattering and TEM. The results indicate that IS does not influence the effects of rP147, rP172, and P173 on mineralization. However, in contrast to the findings for low IS, where both P173 and P148 stabilize initially formed amorphous calcium phosphate (ACP) nanoparticles for >1 d, elongated hydroxyapatite crystals were observed after 24 h using P148 at high IS, unlike that seen with P173. Differences in self-assembly help explain these findings, which suggest that P173 and P148 may play different roles in regulating enamel mineral formation. The present data support the notion that proteolytic processing of P173 is required in vivo to induce the transformation of initial ACP phases to apatitic enamel crystals.

| S-EPMC3448280 | biostudies-literature

Possible dissolution mechanism of alkali lignin in lactic acid-choline chloride under mild conditions.

Project description:In this study, several representative deep eutectic solvents (DESs) were designed to evaluate the solubility for alkali lignin (AL). It was found that DESs with lactic acid (LA) as hydrogen bond donors (HBDs) had good solubility for AL, in which lactic acid(LA) : choline chloride(ChCl) 10 : 1 showed excellent solubility with more than 17 wt% under a relatively mild condition of 60 °C. The results of gel permeation chromatography (GPC), FTIR and 1H and HSQC NMR spectroscopies revealed an important possible dissolution mechanism of AL in LA-ChCl, that is, AL could be depolymerized under the action of LA when dissolved in LA-ChCl. Then, a new connection would form between the phenolic groups on the lignin fragments and ChCl, which is similar to that between ChCl and LA in DES, leading to an increase in the molecule weight of lignin. The new connections could be easily broken under the action of heat (150 °C) or microwave to the redispersion of lignin fragments. The results would provide a theoretic base for the high-value application of lignin in bioresources.

| S-EPMC9057700 | biostudies-literature

Choline phosphate cytidylyltransferase-? is a novel antigen detected by the anti-ERCC1 antibody 8F1 with biomarker value in patients with lung and head and neck squamous cell carcinomas.

Project description:BACKGROUND:The determination of in situ protein levels of ERCC1 with the 8F1 monoclonal antibody is prognostic of survival in patients with non-small cell lung cancer (NSCLC). The authors previously demonstrated that 8F1 recognizes a second nuclear antigen. This antigen was identified and its value as a biomarker of clinical outcomes analyzed. METHODS:The second antigen was identified by mass spectrometry. Protein identity and antibody specificity were confirmed through knockdown and overexpression experiments. Immunohistochemistry of 187 early-stage NSCLC samples and 60 head and neck squamous cell carcinomas (HNSCCs) was used to examine the influence of the second antigen on 8F1 immunoreactivity and its association with patient outcomes. RESULTS:Choline phosphate cytidylyltransferase-? (CCT?, also known as phosphate cytidylyltransferase 1 choline alpha [PCYT1A], a phospholipid synthesis enzyme regulated by RAS) is the second antigen recognized by 8F1. In NSCLC samples, CCT? contributed (rho, 0.38) to 8F1 immunoreactivity. In samples of squamous cell carcinomas of the lung, CCT? was found to be the dominant determinant of 8F1 immunoreactivity, whereas its contribution in other subtypes of lung cancer was negligible. High expression of CCT?, but not ERCC1, was found to be prognostic of longer disease-free survival (log-rank P?=?.002) and overall survival (log-rank P?=?.056). Similarly, in patients with HNSCC, CCT? contributed strongly to 8F1 immunoreactivity (rho, 0.74), and high CCT? expression was found to be prognostic of survival (log-rank P?=?.022 for disease-free survival and P?=?.027 for overall survival). CONCLUSIONS:CCT? is the second antigen detected by 8F1. High CCT? expression appears to be prognostic of survival in patients with NSCLC who are treated by surgery alone and patients with HNSCC. CCT? is a promising biomarker of patient survival and deserves further study.

| S-EPMC4047200 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data