Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

In isolated rat hepatocytes PMA, angiotensin II and to a lesser extent other hormones induce an early genetic response (increased expression of c-fos, c-mos, c-myc and beta-actin) without altering the expression of the glyceraldehyde 3-phosphate dehydrogenase gene. PMA, PDB and O-met-PMA, but not alpha-phorbol, stimulated c-fos expression. The effect of angiotensin II was inhibited by the AT1 antagonist, Losartan (DuP 753) (Ki approx. 25 nM), but not by the AT2 antagonist PD123177. Angiotensin II was much more effective than vasopressin or epinephrine in inducing proto-oncogene expression which suggests that angiotensin II receptors may exert actions in addition to those shared with the receptors for the other calcium-mobilizing hormones. The effect of PMA and angiotensin II on c-fos expression took place rapidly, with half times of 7 and 12 min, respectively. Actinomycin D markedly diminished basal c-fos expression whereas cycloheximide had the opposite effect. Actinomycin D diminished the effect of PMA and angiotensin II but it did not block them. PMA and the calcium-mobilizing hormones increased c-fos expression above the level observed with cycloheximide alone. These data suggest that PMA and the calcium-mobilizing hormones increased both transcription of the c-fos gene and stabilization of the proto-oncogene mRNA.
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PMID:Angiotensin II and active phorbol esters induce proto-oncogene expression in isolated rat hepatocytes. 152 Jul 5

Angiotensin II (AII)- and Arg8-vasopressin (AVP)-regulated gene expression in vascular cells has been reported to contribute to vascular homeostasis and hypertrophy. In this report, AVP-induced expression of plasminogen activator inhibitor (PAI)-2 mRNA in rat microvessel endothelial (RME) cells was identified using differential mRNA display. Further characterization of vasoactive peptide effects on PAI expression revealed that AII stimulated a 44.8 +/- 25.2-fold and a 12.4 +/- 3.2-fold increase in PAI-2 mRNA in RME cells and rat aortic smooth muscle cells (RASMC), respectively. AII also stimulated a 10- and 48-fold increase in PAI-1 mRNA in RME cells and RASMC, respectively. These AII effects were inhibited by either Sar1, Ile8-angiotensin or the AT1 antagonist DuP 735, but were not significantly altered in the presence of the AT2 antagonist PD123319. AII stimulation of RASMC and RME cells also significantly increased both PAI-1 protein and PAI activity released to the culture medium. Inhibition of protein kinase C completely blocked PMA-stimulated induction of PAI-2 mRNA in both cell types and inhibited the AII-stimulated increase in RASMC by 98.6 +/- 2.8%. In contrast, protein kinase C inhibition only partially decreased the AII-stimulated PAI-2 expression in RME cells by 68.8 +/- 11.1%, suggesting that a protein kinase C-independent mechanism contributes to a 6.9 +/- 1.5-fold AII induction of PAI-2 expression in endothelial cells. AII and PMA also stimulated protein tyrosine phosphorylation in RME cells, and the tyrosine kinase inhibitor genistein partially blocked their induction of PAI-2 mRNA. These findings suggest that AII may regulate plasminogen activation in the vasculature by inducing both PAI-1 and PAI-2 expression.
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PMID:Angiotensin II induces plasminogen activator inhibitor-1 and -2 expression in vascular endothelial and smooth muscle cells. 788 82

So far, two angiotensin receptor subtypes, called AT1 and AT2, have been described in an animal model and in human. AT1 mediates almost all known effects of angiotensin II and its gene sequence and regulation is well studied. In contrast, only few data on function and regulation of AT2 are available. The complete mRNA sequence of AT2 has only recently been cloned and sequenced. The angiotensin receptors' receptor density and subtype distribution is organ specific. In the rat, lowest densities are found in the myocardium, followed by kidney, liver, adrenal medulla and cortex. The percentage of AT1 in the different organs amounts to 80, 85, 90, 57 and 10%. Angiotensin receptor subtypes have also been quantitated in human myocardium. There, the relatively unknown subtype AT2 dominates (67%). Myocardial receptor density is low, amounting to about 11 fmol/mg protein corresponding to 1/20-1/50 of the density of beta-adrenergic receptors. Angiotensin receptors in the human heart are present on cardiac fibroblasts and induce proliferation of these cells. Blockade of the renin angiotensin system by ACEI and AT1 antagonists in the rat downregulates angiotensin receptors in liver, kidney and adrenals to about 50% in an organ- and subtype specific manner, whereas cyclosporin A upregulates receptors twice. In end-stage human heart failure, but not in early stages, angiotensin receptors are downregulated to 1/3 of control values. Regulator mechanisms at transcriptional level have been elucidated by reporter gene assays; PMA, an activator of proteinkinase C, stimulates the transcription of the AT1 gene. The organ- and subtypespecific regulation of angiotensin receptors by pharmacological agents and/or cardiovascular diseases can contribute to the understanding of these drugs and of the pathophysiology of the corresponding diseases.
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PMID:[Angiotensin receptors--organ and subtype specific regulation in cardiovascular diseases by modulation of the renin-angiotensin system. Studies of the rat model and in human myocardium]. 858 75

Angiotensin II (Ang II) is a potent regulator of proximal tubule functions, including transport, metabolism, and cell proliferation. The opossum kidney (OK) cell line is a useful model of renal proximal tubule. Mitogen-activated protein (MAP) kinases are rapidly phosphorylated and activated in response to various agonists. We investigated Ang II effects on serine/threonine kinase cascades in OK cells. The major findings of the present study are that Ang II stimulated MAP kinase kinase (MAPKK), MAP kinase (MAPK), and S6 kinase activities, and that it increased phosphorylation of Raf-1 kinase and p42 MAP kinase in OK cells. These stimulations of kinases were dose-dependent (from 10(-6) to 10(-11) M). The time course of activation was sequential; the peak stimulation was reached at 5 to 10 minutes for Raf-1 kinase, MAPKK and MAPK, and at 20 minutes for S6 kinase. The activation of MAPK was inhibited by approximately 70% with prolonged 24-hour PMA pretreatment or in the presence of calphostin C or H-7. Tyrosine kinase inhibitors (genistein and herbimycin) did not inhibit AngII-induced MAPK activity. This activation of MAPK was also inhibited via AT1 receptor antagonist, Dup753 and pertussis toxin. This evidence suggests that the activation of serine/threonine cascades by Ang II is largely dependent on PMA-sensitive PKC, and is not dependent on tyrosine kinase and pertussis toxin.
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PMID:Sequential activation of MAP kinase cascade by angiotensin II in opossum kidney cells. 858 39

Regulation of AT1 receptor mRNA expression is an important determinant of angiotensin II-induced steroidogenesis. We have PCR-amplified the bovine adrenal AT1 receptor coding region using primers designed from the published bovine AT1 receptor sequence. This has been used as a probe on Northern blots to detect changes in the levels of AT1 receptor mRNA in primary cultures of bovine zona fasciculata cells in response to activation of several different signal transduction mechanisms in addition to two major adrenal steroid products, cortisol and aldosterone. AT1 receptor mRNA decreased in response to 6hr AII (10 nM) treatment, but returned to basal levels following 48h AII treatment. This effect was mimicked by the phorbol ester PMA (1 microM) and the calcium ionophore A23187 (1 microM), both singly and in combination. Activation of the cAMP pathway by ACTH (1 nM) and 8-bromo-cAMP (0.1 microM) also decreased AT1 receptor mRNA levels. In contrast, both IGF-1 (10 ng/ml) and potassium ions (12 mM) increased the levels of AT1 receptor mRNA. Finally, cortisol (10 microM) but not aldosterone (100 nM) decreased AT1 receptor mRNA. We conclude that the regulation of AT1 receptor mRNA in bovine zona fasciculata cells could involve several different signal transduction systems in addition to adrenocortical steroids themselves.
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PMID:Multiple signal transduction systems regulate angiotensin II type 1 (AT1) receptor mRNA expression in bovine adrenocortical cells. 896 84

The simian virus 40 large tumor antigen (SV40 Tag) has been ascribed many functions critical to viral propagation, including binding to the mammalian tumor suppressor p53. Recent studies have demonstrated that SV40-transformed murine cells have functional p53. The status of p53 in SV40-immortalized human cells, however, has not been characterized. We have found that in response to ionizing radiation, p53-dependent p21 transactivation activity is present, albeit reduced, in SV40-immortalized cells and that this activity can be further reduced with either dominant negative p53 expression or higher SV40 Tag expression. Furthermore, overexpression of p53 in SV40-immortalized ataxia-telangiectasia (A-T) cells restores p53-dependent p21 induction to typical A-T levels. All SV40-immortalized cell lines exhibited an absence of G1 arrest. Moreover, all SV40-immortalized cell lines exhibited increased apoptosis relative to primary cells in response to ionizing radiation, suggesting that SV40 immortalization results in a unique phenotype with regard to DNA damage responses.
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PMID:The influence of SV40 immortalization of human fibroblasts on p53-dependent radiation responses. 1009 28

Three ataxia telangiectasia (AT) patients have been characterized immunologically and molecularly. Patient 1 presents two nondescribed splicing mutations which affect exons 15 and 21 of the ATM gene. The maternal defect consists of a G > A transition in the first nucleotide of the intron 21 donor splicing site which results in a complete deletion of exon 21. The paternal mutation consists of an A > C transversion in the intron 14 acceptor splicing site which produces a partial skipping of exon 15. Two abnormal alternative transcripts were found, respectively, 17 and 41 nucleotides shorter. Patient 2 presents a homozygous genomic deletion of 28 nucleotides in the last exon of the gene. This deletion changes the normal reading frame after residue 3003 of the protein and introduces a premature stop codon at residue 3008 that could originate a truncated ATM protein. Patient 3, a compound heterozygote, presents a defect which consists of a G > A transition in the first nucleotide of intron 62 donor splicing site which results in a complete deletion of exon 62. The results obtained during a three year period in the proliferation assays show an impaired PMA (phorbol myristate acetate) activation in specific T lymphocyte activation pathways (CD69, CD26, CD28, CD3, PHA, PWM and Con A mediated) but not in others (CD2, ionomycin, and Ig surface receptor). The possible link among specific ATM mutations and abnormal immune responses is unknown.
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PMID:Novel mutations and defective protein kinase C activation of T-lymphocytes in ataxia telangiectasia. 1129 36

Plasma membrane anion exchangers (AEs) regulate myocardial intracellular pH (pH(i)) by Na(+)-independent Cl(-)/HCO(3)(-) exchange. Angiotensin II (Ang II) activates protein kinase C (PKC) and increases anion exchange activity in the myocardium. Elevated anion exchange activity has been proposed to contribute to the development of cardiac hypertrophy. Our Northern blots showed that adult rat heart expresses AE1, AE2, AE3fl, and AE3c. Activity of each AE isoform was individually measured by following changes of pH(i), associated with bicarbonate transport, in transfected HEK293 cells. Exposure to the PKC activator, PMA (150 nmol/L), increased the transport activity of only the AE3fl isoform by 50+/-11% (P<0.05, n=6), consistent with the increase observed in intact myocardium. Cotransfection of HEK293 cells with AE3fl and AT1(a)-Ang II receptors conferred sensitivity of anion transport to Ang II (500 nmol/L), increasing the transport activity by 39+/-3% (P<0.05, n=4). PKC inhibition by chelerythrine (10 micromol/L) blocked the PMA effect. To identify the PKC-responsive site, 7 consensus PKC phosphorylation sites of AE3fl were individually mutated to alanine. Mutation of serine 67 of AE3 prevented the PMA-induced increase of anion transport activity. Inhibition of MEK1/2 by PD98059 (50 micromol/L) did not affect the response of AE3fl to Ang II, indicating that PKC directly phosphorylates AE3fl. We conclude that following Ang II stimulation of cells, PKCepsilon phosphorylates serine 67 of the AE3 cytoplasmic domain, inducing the Ang II-induced increase in anion transport observed in the hypertrophic myocardium.
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PMID:Molecular basis for angiotensin II-induced increase of chloride/bicarbonate exchange in the myocardium. 1173 92

In the present paper the effect of Ang-(1-7) on the distal tubule (Na(+)+K+)ATPase activity was evaluated by using MDCK cells as a model. Confluent cell monolayers were incubated with increasing concentrations of Ang-(1-7) for 30 min. Thereafter, the (Na(+)+K+)ATPase activity was evaluated and a dose-dependent (from 10(-12) to 10(-7) M) inhibition was observed. The maximal inhibitory effect (54%) was reached at the concentration of 10(-8) M. The inhibitory effect of Ang-(1-7) was not affected by the AT2 receptor selective antagonist PD123319 (from 10(-10) to 10(-7) M) but was blocked in a dose-dependent manner by the AT1 receptor selective antagonists losartan (10(-10) M), candesartan (10(-17) M), irbesartan (2 x 10(-12) M) and telmisartan (2 x 10(-16) M). The signaling pathway triggered by stimulation of the AT(1) receptor was also investigated. The PI-phospholipase C (PI-PLC) inhibitor U73122 (5 x 10(-8) M) blocked the inhibitory effect elicited by Ang-(1-7). Involvement of the protein kinase C (PKC) was evidenced by the sensitivity of the inhibitory effect of Ang-(1-7) to calphostin C (6.32 x 10(-7) M) and the lack of additive effects when the cells were co-incubated with Ang-(1-7) and 3.2 x 10(-8) M PMA. Altogether, these results demonstrate that Ang-(1-7) inhibits the (Na(+)+K+)ATPase activity of the prototypic distal tubule cell MDCK through the AT1 receptor-mediated stimulation of PI-PLC/PKC signaling pathway.
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PMID:Modulation of the (Na(+)+K+)ATPase activity by Angiotensin-(1-7) in MDCK cells. 1592 19


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