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)

Basic fibroblast growth factor (bFGF) is a potent mitogen for human bone marrow stromal cells and stimulates haematopoiesis in vitro. We report here that primary human bone marrow cultures contain bFGF and express heparin-like bFGF binding sites on the cell surface and in the extracellular matrix (ECM). bFGF bound predominantly to a 200-kD cell surface heparan sulfate proteoglycan (HSPG), which was also found in conditioned medium. bFGF was released from bone marrow cultures by incubation with phosphatidylinositol-specific phospholipase C (PI-PLC) and, less efficiently, by plasmin. Solubilized bFGF was found as a complex with the 200-kD HSPG. The complex was biologically active as shown by its ability to stimulate plasminogen activator production in bovine aortic endothelial cells. bFGF-HSPG complexes of bovine endothelial cells, however, were not released by PI-PLC. While only trace amounts of the bFGF-binding 200-kD HSPG were released spontaneously from bone marrow cultures, incubation with PI-PLC solubilized almost all of the 200-kD HSPG. The HSPG could be metabolically labeled with ethanolamine or palmitate, which was partially removed by treatment with PI-PLC. These findings indicate linkage of the HSPG to the cell surface via a phosphatidylinositol anchor. Plasmin released the 200-kD HSPG less efficiently than PI-PLC. We conclude that HSPGs of human bone marrow serve as a reservoir for bFGF, from which it can be released in a biologically active form via a dual mechanism; one involving a putative endogenous phospholipase, the other involving the proteolytic cascade of plasminogen activation.
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PMID:Phospholipase C release of basic fibroblast growth factor from human bone marrow cultures as a biologically active complex with a phosphatidylinositol-anchored heparan sulfate proteoglycan. 165 37

Arachidonic acid increased the outputs of prostaglandin (PG) F-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 and Day-15 guinea-pig uterus superfused in vitro. Similar increases in PG output were observed when the arachidonic acid treatment was repeated after an interval of 1, 3 or 5 h. Phospholipase (PL) A-2 increased the outputs of PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 guinea-pig uterus, but repeating the PLA-2 treatment 1 h later failed to stimulate PG output. The increase in outputs of PGF-2 alpha and PGE-2 caused by PLA-2 were partly restored after 3 h and were fully restored after 5 h, whereas the increase in 6-keto-PGF-1 alpha output produced by PLA-2 was only partly restored after 3 and 5 h. PLA-2 had little or no effect on PGF-2 alpha and PGE-2 outputs from the Day-15 guinea-pig uterus initially, and when repeated after 1, 3 and 5 h. This was probably due to the output of these two PGs, particularly of PGF-2 alpha, being stimulated in vivo before removal of the uterus. PLA-2 increased 6-keto-PGF-1 alpha output from the Day-15 uterus initially, but failed to cause a response when administered again 1 h later. After 3 and 5 h, the increase in 6-keto-PGF-1 alpha output from the Day-15 uterus caused by PLA-2 was partly restored. A23187 and PLC increased the outputs of PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 and Day-15 guinea-pig uterus. These responses to A23187 and PLC were reduced (but not abolished) when the two compounds were administered again 1 h later. After 3 and 5 h, the increases in output of PGF-2 alpha and PGE-2 produced by A23187 and PLC had returned to the initial values. The increases in output of 6-keto-PGF-1 alpha from the Day-7 and Day-15 guinea-pig uterus produced by A23187 and PLC were partly restored after 3 and 5 h, except for the response to PLC on Day 7 which was fully restored after 5 h. The results show that there is no failure with time in the mechanism which converts arachidonic acid into PGF-2 alpha in the guinea-pig uterus.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:A possible explanation for the refractoriness of uterine prostaglandin production. 199 60

Phospholipases (PL) A-2 and C stimulated the outputs of prostaglandin (PG) F-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 and Day-15 guinea-pig uterus superfused in vitro. PLC had a more pronounced effect than PLA-2, particularly on the output of PGE-2. The ratios of the outputs of PGF-2 alpha and PGE-2 were similar after stimulation by A23187 and PLA-2, but this ratio was lower after stimulation by PLC. It appears that the stimulation of endometrial PGF-2 alpha synthesis by Ca2+ is via activation of PLA-2 rather than via activation of PLC, although the PLC used was of bacterial origin (which uses phosphatidylcholine as substrate) rather than of mammalian origin (which uses phosphatidylcholine as substrate). Forskolin (which increased endometrial and myometrial cyclic AMP levels) and phorbol 12-myristate-13-acetate had no effect on uterine PG output, indicating that cyclic AMP and protein kinase C are not involved in the stimulation of endometrial PGF-2 alpha synthesis in the guinea-pig. Uterine PG output was not stimulated by 54 mM-KCl, which shows that the pulsatile nature of endometrial PGF-2 alpha synthesis and release is not due to an intermittent, synchronous depolarization of the endometrial cells.
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PMID:Effects of various factors on prostaglandin synthesis by the guinea-pig uterus. 311 14

The activities of microsomal phospholipase A(2) (PLA(2)) and C (PLC) from mouse brain, heart and liver were determined using the substrate 1-palmitoyl-2-N-(4-nitrobenzo-2-oxa-1,3-diazole amino caproyl-phosphatidylcholine (NBD-PC), and the effects of chronic ethanol treatment (ethanol) as well as in vitro addition of various n-alcohols including ethanol on these activities were evaluated. Microsomal membrane fluidity was estimated by diphenylhexatriene anisotropy (gamma). The microsomes from the brain and heart of ethanol-treated mice showed significantly higher PLA(2) activity than those from controls. The brains of ethanol group showed significantly higher PLC activity, while the heart showed significantly lower PLC activity than those of controls. The microsomes from the brain and heart of ethanol-treated mice showed significantly reduced gamma values compared to those of controls. The addition of ethanol in vitro to microsomes was found to increase PLC activity in these tissues, while it decreased PLA(2) activity in a dose-dependent manner. The other n-alcohols showed similar effects on PLA(2) and PLC activity in the live microsomes, while decreases were observed the gamma values in a dose-dependent manner. These results suggest that the change in the membrane fluidity associated with addition of alcohols is a prerequisite for the changes in PLA(2) and PLC activities. In addition, our findings suggest that these changes may play a major role in the cellular injury associated with chronic ethanol treatment in the mouse.
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PMID:Effects of ethanol on phospholipases in the mouse brain, heart and liver. 886 Sep 51

We characterized a new iodinated, high affinity, linear V1a vasopressin antagonist, phenylacetylD-Tyr(Et)Phe-Gln-Asn-Lys-Pro-Arg-Tyr-NH2. The antagonist bound specifically to the V1a vasopressin receptor in crude rat liver membranes with an apparent Kd value of 0.168 nM. This affinity is approximately 1 order of magnitude greater than that of the natural agonist, vasopressin. The inhibitory activity of the antagonist can be demonstrated by its inability to elicit activation and uncoupling of G proteins from the receptor. Thus, after occupancy of receptor sites in rat liver membranes with labeled antagonist and detergent solubilization, the labeled receptor (approximately 60 kDa) was eluted as a stable 400-kDa complex on size-exclusion chromatography. In contrast, when the receptor sites were occupied by the agonist [3H]vasopressin, the receptor eluted as a 60-kDa peak. Coincubation of membranes with iodinated antagonist and an excess of unlabeled vasopressin caused both reduced antagonist binding and a complete shift from the 400-kDa to the 60-kDa peak. The addition of vasopressin to unliganded 400-kDa fractions resulted in a 75% increase in [35S]guanosine-5'-O-(3-thio)triphosphate binding activity, indicating that the 400-kDa fraction contains complexes between the V1a receptor and G proteins. The vasopressin-elicited increase was inhibited by antagonist. Using specific antibodies and immunoadsorption to protein A/Sepharose columns, we found that G protein isotypes G(alpha q/11), G(alpha i3), and G(alpha s), and effector enzymes PLC-beta1, PLC-gamma2 and PLA-2 were associated with the antagonist-labeled receptor in the 400-kDa fraction. Because the 400-kDa complex was found in the absence of ligand, the V1a receptor and the appropriate G proteins and effector enzymes are likely preassociated with each other and do not aggregate after antagonist addition. The association of V1a receptor with the different specific G proteins and effector enzymes is consistent with the multiple actions of vasopressin on liver cells. Antibodies directed against a portion of the carboxyl-terminal domain of the V1a receptor interacted with 60-kDa antagonist-occupied receptor but not with receptor in the 400-kDa complex. These results suggest that the carboxyl-terminal region of the receptor is sterically hindered when coupled to G proteins. The iodinated linear vasopressin antagonist therefore allows stable receptor/G protein complexes and can be an important tool (along with the antisera) for use in the study of factors that control V1a receptor/G protein coupling.
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PMID:A new linear V1A vasopressin antagonist and its use in characterizing receptor/G protein interactions. 920 26

Vascular endothelial growth factor (VEGF) and placenta growth factor (PIGF) are structurally related growth factors for endothelial cells. VEGF binds to the related receptor tyrosine kinases Flt 1 and KDR/Flk 1 with high affinity, whereas PlGF binds only to Flt 1. Ligand-stimulated KDR is known to transduce signals for cellular activity such as proliferation and migration, whereas weak or no responses have been recorded for Flt 1. We examined VEGF and PlGF for their capacity to stimulate signal transduction in porcine aortic endothelial cells expressing Flt 1 or KDR. VEGF had essentially no effect on Flt 1 expressing cells, but induced DNA synthesis and migration of KDR expressing cells. PIGF on the other hand induced DNA synthesis but not migration of the Flt 1 cells. In agreement, MAP kinase, examined as a marker for DNA synthesis, was activated both by VEGF-stimulation of the KDR cells and by PlGF-stimulation of the Flt 1 cells. In contrast, phospholipase C-gamma (PLC-gamma), was tyrosine phosphorylated only in VEGF stimulated KDR cells, and not in the PlGF-stimulated Flt 1 cells, which is in agreement with a role for PLC-gamma in cellular migration. We furthermore examined induction of protein levels of plasminogen activator (PA), which was evident in the PlGF-stimulated Flt 1 cells, but not in the VEGF-stimulated KDR cells. These data show that Flt 1 is able to mediate an array of biological signals when appropriately stimulated and that the pattern of responses of PlGF-stimulation of Flt 1 is distinct from the pattern of responses to VEGF-stimulation of KDR.
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PMID:Placenta growth factor stimulates MAP kinase and mitogenicity but not phospholipase C-gamma and migration of endothelial cells expressing Flt 1. 946 61

Abnormal glucose handling in the proximal tubule may play an important role in the development of diabetic nephropathy. Thus, the present study was designed to examine the effect of high glucose on alpha-methyl-D-glucopyranoside (alpha-MG) uptake and its signaling pathways in the primary cultured rabbit renal proximal tubule cells (PTCs). When PTCs were preincubated with 25 or 50 mM glucose for 4 h, 25 or 50 mM glucose significantly inhibited alpha-MG uptake, while 25 or 50 mM mannitol and L-glucose did not affect. Actinomycin D and cycloheximide did not block the effect of high glucose on alpha-MG uptake. Twenty-five millimoles glucose-induced inhibition of alpha-MG uptake was blocked by mepacrine and AACOCF(3), phospholipase A(2) (PLA(2)) inhibitors. Twenty-five millimoles of glucose, not mannitol or L-glucose, significantly increased the [(3)H]-arachidonic acid (AA) release compared to control. In addition, the 25 mM glucose-induced [(3)H]-AA release was completely blocked by mepacrine or AACOCF(3). Indomethacin, a cyclooxygenase inhibitor, blocked the high glucose-induced inhibition of alpha-MG uptake, although econazole, cytochrome P-450 a epoxygenase inhibitor, and nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, did not. On the other hand, staurosporine and bisindolylmaleimide I, protein kinase C (PKC) inhibitors, blocked 25 mM glucose-induced increase of [(3)H]-AA release and inhibition of alpha-MG uptake. However, neomycin, U 73122, and phospholipase c(PLC) inhibitors did not block the effect of 25 mM glucose on [(3)H]-AA release and alpha-MG uptake. Pretreatment of methoxyverapamil, an L-type Ca(2+) channel blocker, abolished 25 mM glucose-induced increase of [(3)H]-AA release. Indeed, 25 mM glucose increased translocation of cPLA(2) from cytosolic fraction to membrane fraction. In conclusion, the present results demonstrate that high glucose inhibits alpha-MG uptake by the increase of AA release via the activation of PKC.
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PMID:High glucose-induced inhibition of alpha-methyl-D-glucopyranoside uptake is mediated by protein kinase C-dependent activation of arachidonic acid release in primary cultured rabbit renal proximal tubule cells. 1079 10

We have constructed a cell line of 3T3-L1 which can efficiently express human GHR (3T3-L1-hGHR) after differentiation to adipocytes. The expressed hGHR was detected as two bands with approximate molecular sizes of 120K by Western analysis using hGHR specific monoclonal antibody. Maximum lipolytic activity induced by hGH in the 3T3-L1-hGHR was enhanced 10-fold as compared to that in 3T3-L1, suggesting that expressed hGHR is functionally active. Comparative analysis using bGH and hGH revealed that 70% of lipolysis stimulation by 1-10 ng/ml hGH could be attributed to hGHR-mediated response. Analyses on inhibition and phosphorylation of signaling molecules suggested that GH-induced lipolysis stimulation is dependent on gene expression and not mediated through PKA-, PKC-, PLA-, PLC-, nor MAPK-pathway but possibly through JAK-STATs pathway. Duration of STAT5 activation by hGH continued up to 48 h. We also revealed that 22 K hGH isoform, 20K hGH which has been reported as a weaker agonist for GH-induced lipolysis stimulation, possesses equipotent activity and shows stronger action in the presence of hGHBP as compared to 22 K hGH. Taken together we conclude that the hGH-induced lipolysis was not mediated through MAP-, PKA-, PKC-, nor PLA-pathway but might be mediated through STAT pathway and that 20K hGH might show higher lipolytic activity than 22 K hGH in adipose tissue that produces a large amount of GHBP.
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PMID:GH induced lipolysis stimulation in 3T3-L1 adipocytes stably expressing hGHR: analysis on signaling pathway and activity of 20K hGH. 1085 5

We previously described 3 bioactive oxidation products of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (PAPC) containing oxovaleroyl (POVPC), glutaroyl (PGPC), and epoxyisoprostane (PEIPC) groups at the sn-2 position that were increased in minimally modified/oxidized low density lipoprotein (MM-LDL) and rabbit atherosclerotic lesions. We demonstrated specific and contrasting effects of POVPC and PGPC on leukocyte-endothelial interactions and described an effect of PEIPC on monocyte binding. The major purpose of the present study was to determine the effects of structural changes on the bioactivities of these 3 lipids. We demonstrate herein that the group at the sn-2 position determines the specific bioactivity and that the substitution of stearoyl for palmitoyl at the sn-1 position or ethanolamine for choline at the sn-3 position of the phospholipid did not alter bioactivity. Oxidized PAPC, oxidized 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine, and oxidized 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphorylethanolamine stimulated monocyte binding and inhibited lipopolysaccharide-induced expression of the neutrophil-binding molecule E-selectin. Furthermore, all oxovaleroyl phospholipids but not the glutaroyl phospholipids induced monocyte binding without an increase in vascular cell adhesion molecule-1 (VCAM-1) expression and inhibited lipopolysaccharide-induced E-selectin expression. In contrast, glutaroyl phospholipids but not oxovaleroyl phospholipids stimulated E-selectin and VCAM-1 expression. We further demonstrate that all parts of the phospholipid molecules are required for these bioactivities. Hydrolysis with phospholipase (PL) A(1), PLA(2), and PLC strongly reduced the bioactivities of POVPC, PGPC, and mixed isomers of PEIPC. PLD had a smaller but still significant effect. The effects of POVPC and PEIPC could be abolished by sodium borohydride treatment, indicating the importance of the reducible groups (carbonyl and epoxide) in these molecules. In summary, these studies identify 6 new bioactive, oxidized phospholipids that are increased in MM-LDL and, where measured, in atherosclerotic lesions. They thus suggest that a family of phospholipid oxidation products containing oxovaleroyl, glutaroyl, and epoxyisoprostane at the sn-2 position play an important role in the regulation of leukocyte-endothelial interactions, bioactivity being in part controlled by several types of phospholipid hydrolases.
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PMID:Determinants of bioactivity of oxidized phospholipids. Specific oxidized fatty acyl groups at the sn-2 position. 1103 Dec 11

Growth plate chondrocytes from both male and female rats have nuclear receptors for 17beta-estradiol (E(2)); however, recent studies indicate that an alternative pathway involving a membrane receptor may also be involved in the female cell response. E(2) directly affects the fluidity of chondrocyte membranes derived from female, but not male, rats. In addition, E(2) activates PKC in a nongenomic manner in female cells, and chelerythrine, a specific inhibitor of PKC, inhibits E(2)-dependent alkaline phosphatase activity in these cells, indicating PKC is involved in the signal transduction mechanism. The aims of this study were: (1) to examine if PKC mediates the effect of E(2) on chondrocyte proliferation, differentiation, and matrix synthesis; and (2) to determine the pathway that mediates the membrane effect of E(2) on PKC. Confluent, fourth passage resting zone (RC) and growth zone (GC) chondrocytes from female rat costochondral cartilage were treated with 10(-10) to 10(-7) M E(2) in the presence or absence of the PKC inhibitor chelerythrine, and changes in alkaline phosphatase specific activity, proteoglycan sulfation, and [3H]thymidine incorporation were measured. To examine the pathway of PKC activation, chondrocyte cultures were treated with E(2) in the presence or absence of genistein (an inhibitor of tyrosine kinases), U73122 or D609 (inhibitors of phospholipase C [PLC]), quinacrine (an inhibitor of phospholipase A(2) [PLA(2)]), and melittin (an activator of PLA(2)). Alkaline phosphatase specific activity and proteoglycan sulfation were increased and [3H]thymidine incorporation was decreased by E(2). The effects of E(2) on all parameters were blocked by chelerythrine. Treatment of the cultures with E(2) produced a significant dose-dependent increase in PKC. U73122 dose-dependently inhibited the activation of PKC in E(2)-stimulated female chondrocyte cultures. However, the classical receptor antagonist ICI 182780 was unable to block the stimulatory effect of E(2) on PKC. Moreover, the classical receptor agonist diethylstilbestrol (DES) had no effect on PKC, nor did it alter the stimulatory effect of E(2). Inhibition of tyrosine kinase and PLA(2) had no effect on the activation of PKC by E(2). The PLA(2) activator also had no effect on PKC activation by E(2). E(2) stimulated PKC activity in membranes isolated from the chondrocytes, demonstrating a direct membrane effect for this steroid hormone. These data indicate that the rapid nongenomic effect of E(2) on PKC activity in chondrocytes from female rats is sex-specific and dependent upon a G-protein-coupled phospholipase C.
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PMID:The membrane effects of 17beta-estradiol on chondrocyte phenotypic expression are mediated by activation of protein kinase C through phospholipase C and G-proteins. 1107 Mar 50


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