Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phospholipase D (PLD) is present in human placental tissue. Since purinergic receptor agonists activate PLD in many different cell types, we evaluated the purinergic activation of the enzyme in cultured trophoblasts from the placenta. We found that P(2) receptor agonists stimulate PLD. The preferred ligand for P(2X7) (P(2Z)) receptor subtype, BzBz-ATP (10(-3)M ), induced the enzyme more than ten times over basal (unstimulated) activity, while ATP caused a much smaller increase. ATPgammaS, ADP and UTP were even less effective, compared to BzBz-ATP or ATP. AMP and alpha,beta-methyl-ATP, a P(2X) agonist that is uniquely inactive on the P(2X7) subtype, had no effect. This represents the first suggestion of the presence of the P(2X7) type of receptor in human trophoblasts that was directly confirmed by immunoblot detection. The action of BzBz-ATP was dependent upon the presence of calcium in the culture medium and was inhibited by high (5m M ) Mg(++) concentration. P(2X7) receptor subtype specific antagonists, ATP-2',3'-dialdehyde (o-ATP), CBB and the broad specificity P(2) inhibitor PPADS inhibited the effect of BzBz-ATP. Pertussis toxin treatment did not inhibit the effect. Down-regulation of cPKC/nPKC isoforms by prolonged PMA treatment (36 h, 10(-7)M ) prevented the stimulation of PLD by P(2) agonists or the calcium ionophore A-23187. PLA(2) inhibitors did not block the effect of BzBz-ATP. The possibility for a calcium influx related interdependence of PLC and PLD was evaluated. For PLC activation, UTP and ATP surpassed BzBz-ATP, while ionophore did not elevate PLC (assessed by IP(3) measurements). This suggested the predominance of a P(2Y2) receptor in the whole cell in gross activation of PLC. PLD was affected with a reversed order of potency. These results and the dependence of PLD on PKC activity implies that a restricted, membrane localized calcium flux activates PKC and in turn, mediates the P(2X7) dependent stimulation of PLD. This may have implications for physiologic regulation of trophoblast function.
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PMID:Regulation of phospholipase D in human placental trophoblasts by the P(2) purinergic receptor. 1236 78

Basolateral transport of organic anions (OAs) into mammalian renal proximal tubule cells is a tertiary active transport process. The final step in this process involves movement of OA into the cells against its electrochemical gradient in exchange for alpha-ketoglutarate (alphaKG) moving down its electrochemical gradient. Two homologous transport proteins (OAT1 and OAT3) that function as basolateral OA/alphaKG exchangers have been cloned and sequenced. We are in the process of determining the functional distribution and regulation of OAT1 and OAT3 in renal tubules. We are using rabbit OAT1 (rbOAT1) and OAT3 (rbOAT3) expressed in heterologous cell systems to determine substrate specificity and putative regulatory steps and isolated rabbit proximal renal tubule segments to determine functional distribution and physiological regulation of these transporters within their native epithelium. Rabbit OAT1 and OAT3 differ distinctly in substrate specificity. For example, rbOAT1 has a high affinity for the classical renal OA transport substrate, p-aminohippurate (PAH), whereas rbOAT3 has no affinity for PAH. In contrast, rbOAT3 has a high affinity for estrone sulfate (ES), whereas rbOAT1 has only a very slight affinity for ES. Both rbOAT1 and rbOAT3 appear to have about the same affinity for fluorescein (FL). These differences and similarities in substrate affinities make it possible to functionally map transporters along the renal tubules. Initial data indicate that OAT1 predominates in S2 segments of the rabbit proximal tubules, but studies of other segments are just beginning. Transport of a given substrate in any tubule segment depends on both the affinity of each transporter which can accept that substrate as well as the level of expression of each of those processes in that particular tubule segment. Basolateral PAH transport (presumably OAT1 activity) appears to be down-regulated by activation of protein kinase C (PKC) and up-regulated via mitogen-activated protein kinase (MAPK) through phospholipase A(2) (PLA(2)), prostaglandin E(2) (PGE(2)), cyclic AMP, and protein kinase A (PKA) activation.
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PMID:The molecular and cellular physiology of basolateral organic anion transport in mammalian renal tubules. 1472 55

Our previous studies demonstrated that a synthetic peptide encompassing residues 185-203 of the noncollagenous (NC1) domain of the alpha3 chain of type IV collagen, named tumstatin, inhibits in vitro melanoma cell proliferation and migration. In the present study, B16F1 melanoma cells were stably transfected to overexpress the complete tumstatin domain (Tum 1-232) or its C-terminal part, encompassing residues 185-203 (Tum 183-232). Tumstatin domain overexpression inhibited B16F1 in vitro cell proliferation, anchorage-independent growth, and invasive properties. For studying the in vivo effect of overexpression, representative clones were subcutaneously injected into the left side of C57BL6 mice. In vivo tumor growth was decreased by -60% and -56%, respectively, with B16F1 cells overexpressing Tum 1-232 or Tum 183-232 compared to control cells. This inhibitory effect was associated with a decrease of in vivo cyclin D1 expression. We also demonstrated that the overexpression of Tum 1-232 or Tum 183-232 induced an in vivo down-regulation of proteolytic cascades involving matrix metalloproteinases (MMPs), especially the production or activation of MMP-2, MMP-9, MMP-13, as well as MMP-14. The plasminogen activation system was also altered in tumors with a decrease of urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA) and a strong increase of plasminogen activator inhibitor-1 (PAI-1). Collectively, our results demonstrate that tumstatin or its C-terminal antitumor fragment, Tum 183-232, inhibits in vivo melanoma progression by triggering an intracellular transduction pathway, which involves a cyclic AMP (cAMP)-dependent mechanism.
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PMID:In vivo overexpression of tumstatin domains by tumor cells inhibits their invasive properties in a mouse melanoma model. 1553 Aug 61

Lysophosphatidylcholine (lysoPC) is implicated in the development of atherosclerosis and certain autoimmune diseases, and is reported to induce tissue-type plasminogen activator (tPA) at the protein level in endothelial cells. This study was designed to investigate the effect of lysoPC on tPA gene expression and the underlying molecular mechanisms in cultured endothelial cells. LysoPC transiently induced the mRNA expression of tPA in endothelial cells. LysoPC also induced the mRNA expression of urokinase-type plasminogen activator (uPA), uPA receptor, and plasminogen activator inhibitor-1, but the kinetics were different from that of tPA. Promoter analysis revealed that the cyclic AMP-responsive element of the tPA gene (tPACRE) is required for lysoPC-induced tPA expression. Furthermore, an electrophoresis mobility shift assay showed that lysoPC increased the binding activity of CRE binding protein to tPACRE. These results indicated that lysoPC transcriptionally upregulated the gene expression of tPA in endothelial cells, at least in part, via tPACRE activation.
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PMID:Lysophosphatidylcholine induces tPA gene expression through CRE-dependent mechanism. 1572 Dec 75

Previous studies have suggested that cathepsin B participates in the joint destruction associated with rheumatoid arthritis (RA). This study examined the activity of cathepsin B (a lysosomal cysteine protease) in human osteoblasts along with its regulation by cyclic AMP and Interleukin-6 (IL-6). Cyclic AMP elevating agents activate cathepsin B and stimulate the secretion of cathepsin B via the secretion of IL-6, a potent mediator of RA. This study investigated the induction of cathepsin B using the proinflammatory cytokine in human osteoblasts (MG-63) in relation to p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappa B transcription factor. When added to MG-63 cells, IL-6 stimulated the production of cathepsin B, which was reduced significantly by the addition of SB203580, a specific p38 MAPK inhibitor. In addition, the release of IL-6 was also inhibited by either pyrrolidine dithiocarbamate (PDTC) or NF-kappaB SN50, which are potent NF-kappaB inhibitors. Both NF-kappaB inhibitors had a larger inhibitory effect on the activity of cathepsin B in the presence of SB203580. IL-6 stimulated the NF-kappaB binding affinity as well as the activation of p38 MAP kinase, leading to the release of cathepsin B. However, SB203580 had no effect on the IL-6-induced activation of NF-kappaB, and neither of the NF-kappaB inhibitors decreased the level of p38 MAPK activation in the IL-6-stimulated osteoblasts. Moreover, IL-6 increased the activity of urokinase type plasminogen activator (uPA) in MG-63 cells, which was inhibited by SB203580, PDTC and NF-kappaB SN50. This strongly suggests that p38 MAPK and NF-kappaB are essential to the IL-6-induced activation of cathepsin B or uPA and that these two IL-6-activated pathways can act independently.
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PMID:Interleukin-6 and cyclic AMP stimulate release of cathepsin B in human osteoblasts. 1784 65

Horizontal gene transfer events followed by proper regulatory integration of a gene drive rapid evolution of bacterial pathogens. A key event in the evolution of the highly virulent plague bacterium Yersinia pestis was the acquisition of plasmid pPCP1, which carries the plasminogen activator gene, pla. This promoted the bubonic form of the disease by increasing bacterial dissemination from flea bite sites and incidentally enhanced replication in respiratory airways during pneumonic infection. We determined that expression of pla is controlled by the global regulator cyclic AMP (cAMP) receptor protein (Crp). This transcription factor is well conserved among distantly related bacteria, where it acts as a soluble receptor for the ubiquitous signaling molecule cAMP and controls a global network of metabolic and stress-protective genes. Crp has a similar physiological role in Y. pestis since loss of its function resulted in an inability to metabolize a variety of nonglucose substrates. Activation of pla expression requires a transcription activation element of the pla promoter that serves as a Crp binding site. Crp interaction with this site was demonstrated to occur only in the presence of cAMP. Alteration of the Crp binding site nucleotide sequence prevented in vitro formation of Crp-DNA complexes and inhibited in vivo expression of pla. The placement of pla under direct regulatory control of Crp highlights how highly adapted pathogens integrate laterally acquired genes to coordinate virulence factor expression with global gene networks to maintain homeostasis through the infectious life cycle.
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PMID:Direct transcriptional control of the plasminogen activator gene of Yersinia pestis by the cyclic AMP receptor protein. 1793 99

The phospholipase A(2) (PLA(2))-prostanoid cascade is involved in cannabinoid receptor-mediated neuronal functions. We investigated the signaling mechanism for the release of arachidonic acid by cannabinoids, 2-arachidonoyl glycerol (2-AG) and HU210, in rat PC12 cells and in primary cultured cells from the mouse cerebellum. The effect of selective inhibitors for signaling pathways and/or enzymes (alpha type cytosolic PLA(2) (cPLA(2)alpha), G protein, Src kinases, phospholipase C, protein kinase C) was assessed. Methods included translocation of the chimeric protein GFP-cPLA(2)alpha, the activities of Src family kinases, Ca(2+)-dependent fluorescence and cyclic AMP accumulation. Treatment with 2-AG and HU210 at greater concentrations than 3 muM caused the release of arachidonic acid, and the response was inhibited by AM251 (an antagonist of cannabinoid CB(1) receptor) and by pyrrophenone (a selective inhibitor of cPLA(2)alpha) in PC12 cells. The cannabinoid treatment caused the intracellular translocation of cPLA(2)alpha and an increase in the intracellular Ca(2+) level. Treatment with HU210 caused tyrosine phosphorylation of Src and Fyn, and increased their kinase activities. Pretreatment with inhibitors of tyrosine kinases or phospholipase C abolished the cannabinoids-induced release of arachidonic acid and Ca(2+) response, and protein kinase C inhibitor reduced the release of arachidonic acid. 2-AG caused the release of arachidonic acid from cultured cells of the mouse cerebellum via similar mechanisms. These data reveal that cannabinoids activated cPLA(2)alpha in a Src-phospholipase C-protein kinase C-dependent manner probably via cannabinoid CB(1) receptor and/or CB(1)-like receptor in neuronal cells.
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PMID:Release of arachidonic acid by 2-arachidonoyl glycerol and HU210 in PC12 cells; roles of Src, phospholipase C and cytosolic phospholipase A(2)alpha. 1853 71

The cyclic AMP receptor protein (CRP) is a bacterial regulator that controls more than 100 promoters, including those involved in catabolite repression. In the present study, a null deletion of the crp gene was constructed for Yersinia pestis bv. microtus strain 201. Microarray expression analysis disclosed that at least 6% of Y. pestis genes were affected by this mutation. Further reverse transcription-PCR and electrophoretic mobility shift assay analyses disclosed a set of 37 genes or putative operons to be the direct targets of CRP, and thus they constitute the minimal CRP regulon in Y. pestis. Subsequent primer extension and DNase I footprinting assays mapped transcriptional start sites, core promoter elements, and CRP binding sites within the DNA regions upstream of pla and pst, revealing positive and direct control of these two laterally acquired plasmid genes by CRP. The crp disruption affected both in vitro and in vivo growth of the mutant and led to a >15,000-fold loss of virulence after subcutaneous infection but a <40-fold increase in the 50% lethal dose by intravenous inoculation. Therefore, CRP is required for the virulence of Y. pestis and, particularly, is more important for infection by subcutaneous inoculation. It can further be concluded that the reduced in vivo growth phenotype of the crp mutant should contribute, at least partially, to its attenuation of virulence by both routes of infection. Consistent with a previous study of Y. pestis bv. medievalis, lacZ reporter fusion analysis indicated that the crp deletion resulted in the almost absolute loss of pla promoter activity. The plasminogen activator encoded by pla was previously shown to specifically promote Y. pestis dissemination from peripheral infection routes (subcutaneous infection [flea bite] or inhalation). The above evidence supports the notion that in addition to the reduced in vivo growth phenotype, the defect of pla expression in the crp mutant will greatly contribute to the huge loss of virulence of this mutant strain in subcutaneous infection.
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PMID:The cyclic AMP receptor protein, CRP, is required for both virulence and expression of the minimal CRP regulon in Yersinia pestis biovar microtus. 1871 Aug 63

Latitudinal comparisons of the Southern Ocean limpet, Nacella concinna, and clam, Laternula elliptica, acclimated to 0.0 degrees C, were used to assess differences in thermal response to two regimes, 0.0, 5.1 to 10.0 degrees C and 2.5, 7.5 to 12.5 degrees C, raised at 5.0 degrees C per week. At each temperature, tissue energy status was measured through a combination of O(2) consumption, intracellular pH, cCO(2), citrate synthase (CS) activity, organic acids (succinate, acetate, propionate), adenylates (ATP, ADP, AMP, ITP, PLA (phospho-L-arginine)) and heart rate. L. elliptica from Signy (60 degrees S) and Rothera (67 degrees S), which experience a similar thermal regime (-2 to +1 degrees C) had the same lethal (7.5-10.0 degrees C), critical (5.1-7.5 degrees C) and pejus (<5.1 degrees C;=getting worse) limits with only small differences in biochemical response. N. concinna, which experiences a wider thermal regime (-2 to +15.8 degrees C), had higher lethal limits (10.0-12.5 degrees C). However, at their Northern geographic limit N. concinna, which live in a warmer environment (South Georgia, 54 degrees S), had a lower critical limit (5.1-10.0 degrees C; O(2), PLA and organic acids) than Rothera and Signy N. concinna (10.0-12.5 degrees C). This lower limit indicates that South Georgia N. concinna have different biochemical responses to temperatures close to their thermal limit, which may make them more vulnerable to future warming trends.
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PMID:Geographical variation in thermal tolerance within Southern Ocean marine ectotherms. 1953 33

The effects of Na-butyrate on the physiological behaviour and on the specific productivity of recombinant tissue plasminogen activator (t-PA) Chinese Hamster Ovary (CHO) cells were characterized. Batch cultures were performed in a 3.5-L bioreactor. Na-butyrate was added either at the mid-exponential growth phase (48 h) or at the end of the exponential growth phase (74 h). The cultures with Na-butyrate showed higher net specific productivity of t-PA and lower final cell density and viability. Maximum specific productivity of t-PA for all cultures coincided with the early plateau phase (84 h). The cell's specific oxygen uptake rate (qO2) increased after the Na-butyrate addition and remained higher than that of the controlled culture. Triphosphate nucleotides, ADP, AMP and UDP-sugars all increased after 84 h in the cultures with Na-butyrate, showing different behaviours when Na-butyrate was added at 48 h or 74 h. Na-butyrate did not affect the cell's adenylate energy charge until the cell's viability started to decrease (156-168 h). The controlled culture and the culture with Na-butyrate addition, showed at 74 h, similar time trends as for purine and nucleotide ratios ((ATP+GTP)/(UTP+CTP) and UTP/ATP) with clear shifts in behaviour at 84 h and 168 h. However, the addition of Na-butyrate at 48 h resulted in damped variations of purine and nucleotide ratios in comparison to both the control culture and the culture with Na-butyrate addition at 74 h.
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PMID:Na-butyrate sustains energetic states of metabolism and t-PA productivity of CHO cells. 1961 65


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