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:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Renin-angiotensin (RA) system plays an important role in cardiovascular homeostasis. Here, we have described the recent progress in our study of renin release as well as the cellular action of angiotensin II. (1) Microdissection of an isolated afferent artery with or without macula densa (MD) has revealed that renin release is regulated by NaCl exposure to MD. Furosemide, prostaglandins (PGE2 and PGI2) and adenosine modulate its function. (2) Angiotensin (ang) II increases cytosolic free calcium and induces the formation of inositolphosphates in vascular smooth muscle cells. Deduced protein structure of ang II receptor (AT1-R) cDNA has indicated the presumed link of AT1-R with phospholipase C. Through the cellular action, ang II has been reported to regulate gene expression.
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PMID:[Mechanism of renin release and cellular action of angiotensin II]. 129 35

Mesangial cells possess a variety of receptors for hormones and autacoids. They are also equipped with ectoenzymes whose function may be to control the availability of autacoids and hormones at their receptor sites. Several examples are considered. Receptors for angiotensin II (AII) are present both on murine and human mesangial cells. One single group of receptors has been demonstrated in each of these preparations. Mesangial cell AII receptors are linked to phospholipase C via a G protein. They belong to the AT1 subtype because (125I)AII is displaced from its binding sites preferentially by AT1 antagonists such as DUP 753 and EXP 3,174, whereas AT2 antagonists are much less potent. AT1 antagonists suppress the biological effects of AII in mesangial cells, including the stimulation of intracellular calcium concentration and the increase of prostaglandin synthesis and of (3H)leucine incorporation. Mesangial cells also have receptors for atrial natriuretic factor, but the distribution between B receptors with guanylate cyclase activity and clearance (C) receptors varies with the species. Both types are present in murine mesangial cells, whereas only C receptors are found in human mesangial cells. In contrast, human epithelial cells possess both B and C receptors. Ecto-5'-nucleotidase activity results in the production of adenosine, which acts on mesangial cells through A1 and A2 receptors. This enzyme is markedly induced in rat mesangial cells by interleukin-1, whose effect is mediated in part by prostaglandin E2 and cAMP. Various other cAMP-stimulating agents also induce 5'-nucleotidase expression in rat mesangial cells. Ectopeptidases are present in all glomerular cell types but essentially in epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cell surface receptors and ectoenzymes in mesangial cells. 131 10

To examine whether the subpopulation of the rat type 1 angiotensin II (AII) receptor (AT1A) couples with a single or multiple signal transduction pathways, we constructed Chinese hamster ovary (CHO) cell lines producing the recombinant receptor. The expressed AT1A receptor exhibits typical pharmacological characteristics of the AT1 receptor, known to mediate the main physiological function of AII. Addition of AII to the CHO cells induced a rapid, transient increase in intracellular free Ca2+ concentrations ([Ca2+]i) followed by a lower, sustained phase. Nicardipine, a blocker of voltage-dependent L-type Ca2+ channels, attenuated the transient [Ca2+]i response and abolished the sustained phase. The transient phase was also reduced dose-dependently by the phospholipase C inhibitor neomycin. Furthermore, AII inhibited forskolin-evoked cAMP accumulation. These data suggest, although another subpopulation named AT1B is present, that the rat AT1A receptor can independently couple with all three signal transduction pathways known to be induced by AII: i.e., i) activation of phospholipase C resulting in InsP3 generation with a subsequent release of intracellularly stored Ca2+, ii) activation of dihydropyridine-sensitive voltage-dependent Ca2+ channels, and iii) inhibition of adenylate cyclase activity.
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PMID:The rat angiotensin II AT1A receptor couples with three different signal transduction pathways. 137 99

We have shown previously that angiotensin-II (A-II) controls proto-oncogene (c-fos, jun-B and c-jun) mRNA accumulation in bovine adrenal fasciculata cells (BAC). Since BAC contain both subtypes (AT-1 and AT-2) of the A-II receptor, we have investigated which subtype was involved in the effect of A-II on proto-oncogene mRNA by using a selective antagonist for AT-1 (DUP 753) and for AT-2 (CGP 42112A). DUP 753, but not CGP 42112A, inhibited the stimulatory effect of A-II on proto-oncogene mRNA, with ID50s of 4 x 10(-7) M, 7 x 10(-7) M and 2 x 10(-6) M for c-fos, jun-B and c-jun, respectively. Neither of the two antagonists by themselves had a direct effect on proto-oncogene mRNA. As the A-II AT-1 receptors are coupled to the phospholipase C system in BAC, we have investigated whether the A-II effects on the proto-oncogenes were mediated by protein kinase C (PKC) or by Ca2+ calmodulin. First, activation of PKC by the phorbol ester, PMA, increased the level of three proto-oncogene mRNAs, whereas calcium ionophore had no effect. Second, staurosporine, a specific inhibitor of PKC, reduced the stimulatory action of A-II on proto-oncogene mRNA by 80-90%, whereas trifluoroperazine, an inhibitor of calmodulin, had no significant effect. These results demonstrate that the effects of A-II on proto-oncogene mRNA are mediated by AT1 receptor subtypes, mainly through activation of the PKC pathway.
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PMID:Angiotensin-II-induced expression of proto-oncogene (c-fos, jun-B and c-jun) mRNA in bovine adrenocortical fasciculata cells (BAC) is mediated by AT-1 receptors. 142 67

The stimulatory effect of angiotensin II (AT) on the accumulation of inositol phosphates and on aldosterone production is abolished by the AT1 selective receptor antagonist DuP753 while PD123177, an AT2 antagonist, is ineffective. Similarly, a depolarizing effect of AT (inhibition of K+/86Rb efflux) is prevented by DuP753. While mediators derived from phospholipase C activation have a central role in the stimulation of aldosterone production by AT, the effect of AT on K+ permeability is mimicked neither by elevation of cytoplasmic [Ca2+] by ionomycin nor by kinase C activation with phorbol ester. Our results suggest that AT stimulates phospholipase C and the subsequent steroid production by glomerulosa cells through AT1 receptors. In addition some events induced by the activation of AT1 receptors may not be mediated by the activation of phospholipase C.
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PMID:Angiotensin II exerts its effect on aldosterone production and potassium permeability through receptor subtype AT1 in rat adrenal glomerulosa cells. 155 76

Angiotensin II AT1 receptor signal transduction has recently been shown to function through the phospholipase C isozyme, PLC-gamma. Since PLC-gamma is known to interact with phosphotyrosine containing proteins through SH2 domains, we examined the phosphorylation state of the AT1 receptor. Immunoprecipitation of the [32P] labeled AT1 receptor from rat aortic smooth muscle cells followed by alkali hydrolysis demonstrated the presence of tyrosine phosphorylation. Phosphoamino acid analysis of the excised bands demonstrated the presence of phosphoserine and phosphotyrosine residues. A fusion protein comprising the intracellular tail of the AT1 receptor was used to screen for candidate kinases, and the src kinase family displayed high activity. In summary, this study shows that the AT1 receptor is serine and tyrosine phosphorylated in vivo and suggests that a soluble kinase related to the src family may be responsible for the tyrosine phosphorylation.
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PMID:The angiotensin II AT1 receptor is tyrosine and serine phosphorylated and can serve as a substrate for the src family of tyrosine kinases. 751 59

Arginine-specific ADP-ribosyltransferase activity was detected in chicken spleen membrane fraction and the activity was extracted by phosphatidylinositol-specific phospholipase C but not by 1 M NaCl or 1% Triton X-100. The transferase activity extracted from the spleen membrane was thiol-independent and was not inhibited by 200 mM NaCl. Zymographic analysis of the transferase, under non-reducing conditions, showed two forms of active bands corresponding to a molecular mass of 46 and 42 kDa. Thus, the presence of this novel arginine-specific ADP-ribosyltransferase, anchored to the membrane through glycosylphosphatidylinositol and different from previously cloned chicken transferases, AT1 and AT2, is being given further attention.
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PMID:A newly identified GPI-anchored arginine-specific ADP-ribosyltransferase activity in chicken spleen. 757 41

In bovine adrenal zona fasciculata (AZF) cells, angiotensin II (AII) may stimulate depolarization-dependent Ca2+ entry and cortisol secretion through inhibition of a novel potassium channel (IAC), which appears to set the resting potential of these cells. Aspects of the signaling pathway, which couples AII receptors to membrane depolarization and secretion, were characterized in patch clamp and membrane potential recordings and in secretion studies. AII-mediated inhibition of IAC, membrane depolarization, and cortisol secretion were all blocked by the AII type I (AT1) receptor antagonist losartan. These responses were unaffected by the AT2 antagonist PD123319. Inhibition of IAC by AII was prevented by intracellular application of guanosine 5'-O-2-(thio)-diphosphate but was not affected by pre-incubation of cells with pertussis toxin. Although mediated through an AT1 receptor, several lines of evidence indicated that AII inhibition of IAC occurred through an unusual phospholipase C (PLC)-independent pathway. Acetylcholine, which activates PLC in AZF cells, did not inhibit IAC. Neither the PLC antagonist neomycin nor PLC-generated second messengers prevented IAC expression or mimicked the inhibition of this current by AII. IAC expression and inhibition by AII were insensitive to variations in intracellular or extracellular Ca2+ concentration. AII-mediated inhibition of IAC was markedly reduced by the non-hydrolyzable ATP analog adenosine 5'-(beta, gamma-imino)triphosphate and by the non-selective protein kinase inhibitor staurosporine. The protein phosphatase antagonist okadaic acid reversibly inhibited IAC in whole cell recordings. These findings indicate that AII-stimulated effects on IAC current, membrane voltage, and cortisol secretion are linked through a common AT1 receptor. Inhibition of IAC in AZF cells appears to occur through a novel signaling pathway, which may include a losartan-sensitive AT1 receptor coupled through a pertussis-insensitive G protein to a staurosporine-sensitive protein kinase. Apparently, the mechanism linking AT1 receptors to IAC inhibition and Ca2+ influx in adrenocortical cells is separate from that involving inositol trisphosphate-stimulated Ca2+ release from intracellular stores. AII-stimulated cortisol secretion may occur through distinct parallel signaling pathways.
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PMID:Losartan-sensitive AII receptors linked to depolarization-dependent cortisol secretion through a novel signaling pathway. 767 18

Xenopus laevis and mammalian angiotensin AT1 receptors couple to the phospholipase C signal transduction pathway. However, amphibian AII receptors (xAT), unlike mammalian AT1 receptors, do not recognize the non-peptide antagonist Dup 753. To investigate the basis of this distinction, we have isolated a 3.0 kb Xenopus myocardial xAT cDNA that encodes a 41,039 MW protein containing 362 amino acids. The xAT receptor has 60% amino acid identity and 65% nucleotide homology with the coding regions of known mammalian AT1 receptors. xAT receptors expressed in Xenopus oocytes mediate AII-induced Ca2+ mobilization and are pharmacologically distinct from mammalian AT1 receptors. xAT transcripts are present in Xenopus lung, liver, kidney, spleen, and heart, but not in adrenal, intestine, and smooth muscle. Comparative analysis of xAT and AT1 receptors should facilitate elucidation of the structural basis of their binding and activation properties.
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PMID:Molecular cloning, sequencing and functional expression of an amphibian angiotensin II receptor. 768 27

Angiotensin II is an eight amino acid peptide which plays a major role in the regulation of cardiovascular homeostasis. The physiologic effects of angiotensin (Ang) II are mediated by a G-protein coupled receptor, termed AT1, which activates phospholipase C. A major factor regulating angiotensin II receptor function is the rapid desensitization following agonist stimulation. However, despite years of investigation, the mechanism by which the angiotensin receptor is regulated remains unclear. The cloning of the AT-1 receptor and the availability of cell lines which stabily express this receptor has helped elucidate these mechanisms. In this paper, we review the data from our laboratory concerning the post-translational regulation of the angiotensin receptor function.
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PMID:Desensitization of angiotensin receptor function. 769 89


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