(Hypertension. 1995;26:899-904.)
© 1995 American Heart Association, Inc.
Articles |
Vasoactive Diadenosine Polyphosphates Promote Growth of Cultured Renal Mesangial Cells
From Medizinische Klinik IV and Institut für Biochemie, Universität Erlangen-Nürnberg (Germany).
Correspondence to Dr Eckhard Schulze-Lohoff, Medizinische Klinik IV, Universität Erlangen-Nürnberg, Loschgestr 8
, D-91054 Erlangen, FRG.
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Abstract Diadenosine polyphosphates (diadenosine triphosphate, Ap3A; diadenosine tetraphosphate, Ap4A; diadenosine pentaphosphate, Ap5A; diadenosine hexaphosphate, Ap6A) are potent vasoactive molecules stored and released by platelets. We examined whether these dinucleotides might contribute to the glomerular inflammatory response by stimulating the proliferation of mesangial cells. In cultured rat mesangial cells all four tested dinucleotides (10 to 100 µmol/L) significantly stimulated DNA synthesis as measured by [3H]thymidine uptake at 48 hours (x-fold increase compared with unstimulated control cells: Ap3A, 1.5; Ap4A, 1.8; Ap5A, 1.6; Ap6A, 1.6). In combination with the platelet products platelet-derived growth factor, epidermal growth factor, and serotonin, the dinucleotides synergistically increased DNA synthesis. Dinucleotides by themselves increased cell counts by 23% to 43% at day 2 and augmented mesangial cell growth induced by platelet-derived growth factor, epidermal growth factor, and serotonin. Furthermore, dinucleotides (100 µmol/L) rapidly induced a modest increase in expression of the early growth response gene Egr-1 at 30 minutes (x-fold increase over baseline control: Ap3A, 1.9; Ap4A, 2.8; Ap5A, 2.2; Ap6A, 2.1). We found that extracellular Ap4A was metabolized by mesangial cell ectoenzymes to mononucleotides and adenosine, which also have been shown to be mitogenic for mesangial cells. The combination of Ap4A with mononucleotides or adenosine failed to cause additive stimulation of DNA synthesis in mesangial cells. We conclude that diadenosine polyphosphates stimulate proliferation of cultured mesangial cells and augment mesangial cell growth induced by other mitogens released from platelets. Different molecular mechanisms may be involved in dinucleotide-induced mitogenesis of mesangial cells. Direct effects of dinucleotides on cultured mesangial cells appear to play a role because dinucleotides rapidly caused activation of Egr-1. On the other hand, independent or additional effects of the mitogenic metabolites ATP, ADP, AMP, and adenosine may contribute to dinucleotide-induced mesangial cell replication.
Key Words: dinucleotides • cell division • glomerular mesangium
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Introduction |
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The diadenosine polyphosphates (Ap3A, Ap4A, Ap5A, and Ap6A) are recently described vasoactive mediators.1 2 3 4 Large amounts of these dinucleotides are stored and released by the dense granules of platelets1 5 and by the secretory granules of chromaffin cells of the adrenal gland.6 In lower concentrations diadenosine polyphosphates are found in most eukaryotic cells. It was calculated that the extracellular concentrations of diadenosine polyphosphates on degranulation of platelets are at least in the micromolar range.1 Because dinucleotides are less susceptible to degradation, their half-life in the extracellular milieu is considerably longer than that of mononucleotides.1 It is well established that Ap3A and Ap4A regulate platelet aggregation in an autocrine manner. Ap3A is a stimulator and Ap4A an inhibitor of platelet aggregation.5 7 There is increasing evidence that diadenosine polyphosphates function as neurotransmitters in chromaffin cells of the adrenal gland and in the central nervous system.6 8
Recently, Ap5A and Ap6A isolated from human platelets were identified as potent vasoconstrictors.2 Both dinucleotides have a vasopressor action in the isolated perfused rat kidney and aortic rings.2 Intra-aortic injection in the rat caused a prolonged increase in blood pressure.2 By contrast, Ap3A and Ap4A were found to be vasodilators, as shown previously in coronary and mesenteric arteries of the rabbit.3 4 This effect partially depended on nitric oxide and prostacyclin. However, when the endothelial layer was removed from mesenteric arteries, Ap4A acted as a vasoconstrictor under these experimental conditions.3
Glomerulonephritis leading to destruction of the glomerular capillary tuft, ie, the ultrafiltration apparatus, is a main cause of end-stage renal disease.9 The pathogenesis of the chronic inflammatory process in glomeruli is still largely unknown. High blood pressure has been shown to aggravate the clinical course of glomerulonephritis. A characteristic finding in the early phase of most forms of glomerulonephritis is the proliferation of MCs.9 In animal models of glomerulonephritis platelet products have been shown to contribute to the proliferative response of intrinsic glomerular cells.10 11 In addition to the platelet-borne mitogens,12 such as PDGF-BB, EGF, and 5-HT, we recently demonstrated that extracellular mononucleotides such as ATP are potent mitogens for cultured rat MCs.13 Poelstra et al11 14 reported that additional injections of a stable ATP analogue increased proteinuria and oxygen radical production by glomerular neutrophils in anti–Thy-1 glomerulonephritis in the rat. Since the naturally occurring mononucleotides are short-lived molecules, we examined whether the more stable diadenosine polyphosphates—Ap3A, Ap4A, Ap5A, and Ap6A—might contribute to glomerular inflammation in response to injury, eg, by stimulating MC proliferation. We found that all examined dinucleotides are strong comitogens in MCs when used in combination with other platelet-derived mitogens such as PDGF, EGF, and 5-HT. In addition, we observed a stimulatory effect of the diadenosine polyphosphates on the expression of Egr-1, which is thought to be involved in MC mitogenesis. Furthermore, we considered that degradation products of dinucleotides (eg, ATP, ADP, AMP, and adenosine) might contribute to MC replication in culture.
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Methods |
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Materials
[3H]Thymidine and myo-2-[3H]inositol were purchased from Amersham Buchler. DMEM was from Biochrom, FCS from Boehringer, bovine insulin from Sigma Chemical Co, and all plastic articles from Becton Dickinson. Ap3A, Ap4A, Ap5A, and Ap6A were from Sigma. Adenosine 5'-O (3 thio)triphosphate (ATP
S),
adenosine 5'-(
,ß-methylene)triphosphate, adenosine
5'-(ß,-methylene)triphosphate, UTP, adenosine, and
5-HT were also from Sigma. 2-Methylthio-ATP was from Research
Biochemicals Inc. ATP (free of pyrogens), PDGF-BB, and EGF were from
Boehringer.
Cell Culture
Rat MCs were isolated and cultured as
described.15 16 Briefly, kidneys were excised from male
Sprague-Dawley rats (150 to 200 g), and the cortex was
separated from the medulla and homogenized with razor
blades. Glomeruli were isolated from the homogenate by
sequential sieving and collected on a 75-µm sieve. Glomeruli were
seeded in tissue culture flasks (30 000 per 75-cm2 flask)
containing DMEM supplemented with 20% FCS, 5 µg/mL bovine insulin,
100 U/mL penicillin, and 100 µg/mL streptomycin. Primary outgrowth
consisted predominantly of MCs and epithelial cells. After three to
four passages with the use of 0.05% trypsin/0.02% EDTA,
homogeneous cultures of MCs were obtained. Cells showed
typical stellate morphology and uniformly exhibited positive
immunocytochemical staining for Thy-1 (Boehringer) and smooth
muscle cell actin (Serotec). Presence of macrophages,
endothelial cells, and epithelial cells was excluded by
negative staining with antibodies against macrophage antigen
ED-1 (Serotec), factor VIII (Dako), and cytokeratin (Progen). MCs were
frozen in liquid nitrogen at passage 4 and used for experiments at
passages 5 through 25. After passage 5 to 6, the FCS concentration was
reduced to 10%.
Determination of DNA Synthesis and Cell Replication
Cell proliferation was assessed by counting MCs in triplicate
wells (24-well plate) in an automated cell counter (Coulter
Electronics) and by [3H]thymidine uptake as
described.17 Briefly, [3H]thymidine uptake
was performed by seeding of MCs in 96-well microplates (3000 cells per
well). At subconfluency MCs were growth-arrested in DMEM containing
0.5% FCS and 5 µg/mL insulin for 4 days. After agonists were added
to the MCs, DNA synthesis was followed by labeling the cells with
[3H]thymidine (1 µCi/mL) from 0 to 24, 24 to 48, and 48
to 72 hours. At the end of each labeling period MCs were washed twice,
trypsinized, and harvested onto cellulose filters with an automated
cell harvester (Cambridge Technology Inc). Finally, the filters were
counted in a liquid scintillation counter (Beckman Instruments Inc).
These assays were performed in fourfold replicates. The data shown in
the figures were obtained at day 2 when the increase in DNA synthesis
was maximal.
Northern Blot Analysis
Subconfluent MCs in Petri dishes were growth-arrested for 4
days in DMEM containing 0.5% FCS and 5 µg/mL insulin. Agonists were
added to the culture dishes with concentrated stock solutions. After 30
minutes MCs were washed two times with ice-cold PBS. RNA was
isolated from MCs by the guanidinium thiocyanate/phenol/chloroform
extraction method according to Chomczynski and Sacchi.18
The RNA samples (20 µg per lane) were separated by agarose-gel
electrophoresis, transferred to a nylon membrane (Pall Biodyne A), and
fixed by incubation at 80°C for 2 hours. The membrane was hybridized
with a cDNA encoding for Egr-1 (obtained from Dr V.P. Sukhatme, Boston,
Mass) and GAPDH (cDNA obtained from Dr A. Hartner, Erlangen, FRG). For
hybridization, inserts were labeled by random primer
extension.19 The filters were prehybridized for 2 hours at
40°C in a solution containing 50% formamide, 5x SSC (3 mol/L NaCl,
0.3 mol/L trisodium citrate, pH 7.0), 5x Denhardt's solution, 0.1%
SDS, and 200 µg/mL sheared denatured salmon sperm DNA. The filters
were then hybridized for 15 to 20 minutes at 40°C in the same
solution containing approximately 5x106 cpm/mL
32P-labeled cDNA probe. After hybridization membranes were
washed twice with 2x SSC/0.1% SDS at 40°C for 15 minutes and twice
with 0.2x SSC/0.1% SDS at 40°C for 15 minutes. The filters were
air-dried and autoradiographed. The mRNA sizes of Egr-1 and GAPDH
were 3.4 and 1.4 kb, respectively. Quantification of the bands was
performed by densitometry (Laser Scan Densitometer, LKB), and the
intensity of the bands was related to the density of control
hybridization bands of GAPDH.
Analysis of Metabolite Formation From
Diadenosine Polyphosphates
Degradation of tritiated Ap4A was measured as described
previously.20 Briefly, subconfluent MCs in 96-well plates
were washed twice with PBS and incubated with tritiated Ap4A in Hanks'
balanced salt solution buffer for different time periods. After gentle
mixing of the supernatant, aliquots (3 µL) were withdrawn, mixed with
3 µL of unlabeled nucleotides plus adenosine as
markers, and spotted on polyethyleneimine cellulose thin-layer
sheets (Merck). The plates were developed in H2O/LiCl (0.75
mol/L), resulting in a clear separation of all degradation products
concerned (ATP, ADP, AMP, and adenosine). The
nucleotide and adenosine spots were marked under UV
light, cut out, and counted in a liquid scintillation counter. Baseline
counts were subtracted from each experimental value.
Statistical Analysis
Data were analyzed by Student's t test or
ANOVA, as appropriate. A value of P<.05 was considered
statistically significant.
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Results |
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The dinucleotides Ap3A, Ap4A, Ap5A, and Ap6A increased DNA synthesis in cultured rat MCs as measured by [3H]thymidine uptake at 48 hours (Fig 1). The relative increases were Ap3A (100 µmol/L), 1.5-fold; Ap4A (100 µmol/L), 1.8-fold; Ap5A (100 µmol/L), 1.6-fold; and Ap6A (100 µmol/L), 1.6-fold. The dose-response relationship for the mitogenic effect of the dinucleotides alone revealed a maximal effect at 10 to 100 µmol/L (Fig 1). The P2X receptor agonists [adenosine 5'-(
,ß-methylene)triphosphate and
adenosine 5'-(ß,-methylene)triphosphate], the
P2Y agonist (2-methylthio-ATP), and the P2U
agonist (UTP) had no effect, as shown previously.13
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, A), Ap4A (
), 20 ng/mL EGF (
), or 1 µmol/L 5-HT (
).
DNA synthesis measured by [3H]thymidine
(3H-TdR) uptake is shown at 48 hours when maximal
mitogenic responses occurred. DNA synthesis of MCs treated
with solvent buffer alone (PBS/0.1% bovine serum albumin) or
growth factors alone can be read at 0 µmol/L ApnA. Values are
mean±SD (n=6). *P<.05, experimental value compared with
baseline control; +P<.05, experimental value (combined
stimulation) exceeds additive effect of ApnA plus growth factors
(synergistic effect).Because diadenosine polyphosphates are stored in and released from platelets together with other growth factors and are unlikely to act alone in vivo, we examined whether these molecules show cooperative effects on DNA synthesis of MCs when used in combination with the platelet products PDGF-BB, EGF, and 5-HT (Fig 1). All tested dinucleotides exhibited a strong and more than additive stimulation of DNA synthesis when combined with PDGF-BB, EGF, and 5-HT, a phenomenon referred to as synergism21 (PDGF-BB [25 ng/mL], 2.1-fold; PDGF-BB plus Ap3A [100 µmol/L], 4.1-fold; PDGF-BB plus Ap4A [100 µmol/L], 5.2-fold; PDGF-BB plus Ap5A [100 µmol/L], 3.7-fold; PDGF-BB plus Ap6A [100 µmol/L], 4.4-fold; EGF [20 ng/mL], 2.1-fold; EGF plus Ap3A, 4.9-fold; EGF plus Ap4A, 5.9-fold; EGF plus Ap5A, 4.0-fold; EGF plus Ap6A, 4.8-fold; 5-HT [1 µmol/L], 1.9-fold; 5-HT plus Ap3A, 4.5-fold; 5-HT plus Ap4A, 5.8-fold; 5-HT plus Ap5A, 4.5-fold; and 5-HT plus Ap6A, 5.8-fold). For all dinucleotides the synergistic effect on DNA synthesis occurred with a maximal effect at 10 µmol/L. We could not find a statistically significant difference in the mitogenic and comitogenic effects of the various dinucleotides.
We performed direct cell counting to confirm that dinucleotides stimulate both DNA synthesis and MC multiplication (Table 1). At 48 hours Ap3A (100 µmol/L) increased cell counts by 37±12%, Ap4A (100 µmol/L) by 43±8%, Ap5A (100 µmol/L) by 23±4%, and Ap6A (100 µmol/L) by 35±8%. PDGF-BB (25 ng/mL) increased cell counts by 84±6%, EGF (20 ng/mL) by 78±6%, and 5-HT (1 µmol/L) by 75±11%. When combined with PDGF, EGF, or 5-HT, the dinucleotides augmented MC growth induced by these mitogens. However, combined stimulation with growth factors plus dinucleotides resulted in additive but not synergistic increases in cell counts.
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Next, we examined whether dinucleotides might induce expression of genes that are thought to regulate cell growth. Egr-1 has been shown to be rapidly induced by various mitogens, and its expression correlates with mitogenic activity.22 23 We found that the dinucleotides rapidly induced expression of Egr-1 mRNA levels at 30 minutes. The increases were (x-fold increases compared with unstimulated control; mean±SD of four experiments) Ap3A (100 µmol/L), 1.9±0.4 (P<.05); Ap4A (100 µmol/L), 2.8±0.7 (P<.05); Ap5A (100 µmol/L), 2.2±0.5 (P<.05); and Ap6A (100 µmol/L), 2.1±0.6 (P<.05) (Fig 2). Peak Egr-1 mRNA levels were found at 30 minutes, and the maximal effect was observed at 10 to 100 µmol/L of each dinucleotide (data not shown).
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It has been reported for several cell types that dinucleotides are degraded by cell surface ectonucleotidases that may be of importance for the biological effects of extracellular dinucleotides.1 20 Therefore, we examined Ap4A degradation by cultured MCs. After incubation of MCs with tritiated Ap4A and subsequent thin-layer chromatographic analysis, we found that Ap4A is degraded with a variable half-life of 0.5 to 8 hours, depending on the dinucleotide concentration and experimental conditions. We identified adenosine, AMP, ADP, and ATP as metabolites of Ap4A in the cell culture supernatant (Table 2).
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Mitogens that costimulate DNA synthesis in a synergistic manner are
assumed to use different signaling pathways.21 Therefore,
we examined whether Ap4A (100 µmol/L) exhibits synergism with its
metabolites ATP and adenosine or with the stable ATP analogue
ATPS (Table 3). Ap4A in combination
with maximal concentrations of its metabolites did not augment DNA
synthesis further.
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The results of this study demonstrate that Ap3A, Ap4A, Ap5A, and Ap6A stimulate DNA synthesis and cell replication of cultured rat renal MCs, which are smooth muscle–like contractile cells of the glomerulus. This effect was most striking when dinucleotides were combined with other growth factors released from platelets such as PDGF, EGF, or 5-HT. Coincubation of MCs with these growth factors and dinucleotides resulted in increases of DNA synthesis usually evoked in MCs only by high FCS concentrations.
At least three different concepts may explain the mitogenic effect of diadenosine polyphosphates in cultured MCs. First, dinucleotides by themselves may directly stimulate MC proliferation either via specific dinucleotide receptors or via one of the known ATP receptors. Second, dinucleotides are extracellularly metabolized, generating mononucleotides such as ATP, ADP, AMP, and adenosine, which have been shown to be mitogenic for cultured rat MCs.13 24 Third, both mechanisms may contribute to MC mitogenesis.
The first concept, that dinucleotides by themselves may directly stimulate MC proliferation, is supported by our observation that dinucleotides rapidly (at 30 minutes) induced activation of Egr-1 (Fig 2), which is thought to be involved in growth control.22 23 However, one cannot rule out the possibility that this effect may be mediated by mononucleotides because significant release of these metabolites is observed within 20 minutes (Table 2). Furthermore, it is suggested that dinucleotides act by themselves because the dose-response relationship of the mitogenic effect of dinucleotides revealed a maximum at 10 µmol/L, whereas ATP showed no significant mitogenic effect at this concentration when used alone.13 If dinucleotides act by themselves, they may promote growth by stimulating either one of the known ATP receptors or a specific dinucleotide receptor. The first interpretation appears unlikely because we have previously shown that the classic agonists for P2Y, P2X, and P2U receptors do not induce mitogenesis.13 The second hypothesis is difficult to test because our knowledge of this putative receptor is very limited. A dinucleotide or P2D receptor has been proposed by several groups.25 26 27 Hilderman et al25 isolated a putative Ap4A receptor from mouse brain membranes. This receptor is a 30-kD protein expressed on the cell surface of cardiac myocytes.28 The highest levels of this molecule were found in heart tissue, but it is also present in brain, liver, and kidney. At present, specific and metabolically stable agonists and antagonists for the dinucleotide or P2D receptor are lacking, hindering a more detailed study of the role of this putative receptor in dinucleotide-induced mitogenesis in MCs.
The second concept includes the possibility that dinucleotides by themselves have no effect on the proliferation of cultured MCs but act through their mitogenic metabolites, such as mononucleotides and adenosine. This concept is based on the observation that MCs are exposed to mononucleotides and adenosine during stimulation with Ap4A (Table 2). This hypothesis is supported by the finding that Ap4A and mononucleotides failed to produce a synergistic effect on DNA synthesis in MCs (Table 3) and, therefore, appear to use a common mitogenic mechanism.21 However, the concentrations of mononucleotides and adenosine reached on degradation of Ap4A by MCs appear to be lower than the concentrations reported to be required for mononucleotide-induced mitogenesis.13 24 On the other hand, it is possible that mononucleotides continuously released from dinucleotides may be more efficient stimulators of DNA synthesis than mononucleotides given as a bolus in cell culture. In this concept, dinucleotides may play an important role as proagonists or extracellular precursors for mononucleotides and adenosine.
The relative contributions of the discussed mechanisms cannot be determined with certainty until metabolically stable analogues of dinucleotides and specific antagonists for dinucleotide and ATP receptors are available.
Since the dinucleotides exhibit a strong comitogenic effect in the presence of PDGF, which functions as a competence factor in MC mitogenesis,12 15 it is possible that dinucleotides may act as progression factors. Our previous observations have indicated that ATP is a progression factor promoting MC proliferation.13 The fact that dinucleotides and ATP failed to produce additive effects on DNA synthesis of MCs is compatible with this notion.
Diadenosine polyphosphates are found not only in storage vesicles of platelets and chromaffin cells but also in the cytosol of all eukaryotic cell types that have been investigated.1 Their cellular content increases rapidly on oxidative stress and heat shock. Therefore, these molecules have been named "alarmones" and are thought to coordinate the adaptive and self-protective mechanisms of the cell.29 While this potentially critical role of cytosolic diadenosine polyphosphates has not been definitively proved, growing evidence suggests that extracellular dinucleotides function as regulators of platelet aggregation, neurotransmitters, and vasoactive mediators.1 Our study supports the concept that extracellular dinucleotides may also function as modulators of cell growth. In a very recent report30 it was observed that two dinucleotides, Ap5A and Ap6A, stimulate proliferation of cultured MCs and act as progression factors similar to insulin–like growth factor–1. This effect was associated with an increase in intracellular calcium on stimulation with Ap5A and Ap6A. The results of our experiments clearly demonstrate that Ap3A and Ap4A are as potent as Ap5A and Ap6A with respect to mitogenicity. Moreover, we found that the four dinucleotides also synergized with the platelet products EGF and 5-HT and induced an increased expression of Egr-1.
Recently, the role of extracellular mononucleotides as
possible inflammatory and vasoactive mediators in vitro and in vivo has
attracted much attention.31 32 ATP has been shown to be a
mitogen for endothelial cells, vascular smooth muscle
cells, MCs, and several other cell types.13 31 In the rat
model of anti–Thy-1 glomerulonephritis, additional injections of the
ATP analogue ATPS increased proteinuria and oxygen radical
production by glomerular
neutrophils.14 Since mononucleotides are
short-lived molecules in the extracellular space, the more stable
dinucleotides33 are of considerable
interest with regard to the regulation of arterial blood
pressure2 and various processes, such as inflammation,
atherosclerosis, and tissue repair.1 The
dual role of the dinucleotides as regulators in their
own right and as precursors for other mediator molecules, such as ATP
and adenosine, may be of particular importance.
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Selected Abbreviations and Acronyms |
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Acknowledgments |
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This work was supported by the Deutsche Forschungsgemeinschaft, Klinische Forschergruppe "Molekulare Regulationsmechanismen in glomerulären Zellen der Niere." The expert technical assistance of Sandra Reichel is gratefully acknowledged.
Received June 29, 1995; first decision July 25, 1995; accepted August 24, 1995.
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References |
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1. Ogilvie A. Extracellular functions for ApnA. In: McLennan AG, ed. Ap4A and Other Dinucleoside Polyphosphates. London, UK: CRC Press Inc; 1992:229-273.
2. Schlüter H, Offers E, Brüggemann G, van der Giet M, Tepel M, Nordhoff E, Karas M, Spieker C, Witzel H, Zidek W. Diadenosine phosphates and the physiological control of blood pressure. Nature. 1994;367:186-188. [Medline] [Order article via Infotrieve]
3.
Busse R, Ogilvie A, Pohl U. Vasomotor activity
of diadenosine triphosphate and diadenosine
tetraphosphate in isolated arteries. Am J Physiol. 1988;254:H828-H832.
4.
Pohl U, Ogilvie A, Lamontagne D, Busse R.
Potent effects of Ap3A and Ap4A on coronary resistance and
autocoid release of intact rabbit hearts. Am J
Physiol. 1991;260:H1692-H1697.
5. Lüthje J, Ogilvie A. Diadenosine triphosphate (Ap3A) mediates human platelet aggregation by liberation of ADP. Biochem Biophys Res Commun. 1984;118:704-709. [Medline] [Order article via Infotrieve]
6. Castro E, Torres M, Miras-Portugal MT, Gonzalez MP. Effect of diadenosine polyphosphates on catecholamine secretion from isolated chromaffin cells. Br J Pharmacol. 1990;100:360-400.[Medline] [Order article via Infotrieve]
7. Lüthje J, Baringer J, Ogilvie A. Effects of diadenosine triphosphate (Ap3A) and diadenosine tetraphosphate (Ap4A) on platelet aggregation in unfractionated human blood. Blut. 1985;51:405-413. [Medline] [Order article via Infotrieve]
8. Klishin A, Lozovaya N, Pintor J, Miras-Portugal MT, Krishtal O. Possible functional role of diadenosine polyphosphates: negative feedback for excitation in hippocampus. Neuroscience. 1994;58:235-236. [Medline] [Order article via Infotrieve]
9. Sterzel RB, Lovett DH. Interactions of inflammatory and glomerular cells in the response to glomerular injury. In: Wilson C, ed. Immunopathology of Renal Disease. New York, NY: Churchill Livingstone; 1988:137-173.
10. Johnson RJ, Garcia RL, Pritzl P, Alpers CE. Platelets mediate glomerular cell proliferation in immune complex nephritis induced by anti-mesangial cell antibodies in the rat. Am J Pathol. 1989;135:261-269. [Abstract]
11. Poelstra K, Hardonk MJ, Koudstaal J, Bakker WW. Intraglomerular platelet aggregation and experimental glomerulonephritis. Kidney Int. 1990;37:1500-1508. [Medline] [Order article via Infotrieve]
12. Sterzel RB, Schulze-Lohoff E, Marx M. Cytokines and mesangial cells. Kidney Int. 1993;43:S26-S31.
13.
Schulze-Lohoff E, Zanner S, Ogilvie A, Sterzel
RB. Extracellular ATP stimulates proliferation of cultured
mesangial cells via P2-purinergic receptors.
Am J Physiol. 1992;263:F374-F383.
14. Poelstra K, Heynen ER, Baller JFM, Hardonk MJ, Bakker WW. Modulation of anti-Thy-1 nephritis in the rat by adenine nucleotides. Lab Invest. 1992;66:555-563. [Medline] [Order article via Infotrieve]
15.
Méne P, Simonson MS, Dunn MJ. Physiology
of the mesangial cell. Physiol Rev. 1989;69:1347-1424.
16. Lovett D, Ryan JC, Sterzel RB. A thymocyte-activating factor derived from glomerular mesangial cells. J Immunol. 1983;130:1796-1801. [Abstract]
17. Schulze-Lohoff E, Brand K, Fees H, Netzker R, Sterzel RB. Role of ornithine decarboxylase for proliferation of mesangial cells in culture. Kidney Int. 1991;40:684-690. [Medline] [Order article via Infotrieve]
18. Chomczynski P, Sacchi N. Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem. 1987;162:156-157. [Medline] [Order article via Infotrieve]
19. Feinberg AP, Vogelstein B. A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal Biochem. 1983;132:6-13. [Medline] [Order article via Infotrieve]
20. Ogilvie A, Lüthje J, Pohl U, Busse R. Identification and partial characterization of an adenosine (5')tetraphospho(5')adenosine hydrolase on intact bovine aortic endothelial cells. Biochem J. 1989;259:97-103. [Medline] [Order article via Infotrieve]
21.
Rozengurt E. Early signals in the
mitogenic response. Science. 1986;234:161-166.
22. Sukhatme VP, Cao X, Chang LL, Tsai-Morris CH, Stamenkovich D, Ferreira PCP, Cohen DR, Edwards SA, Shows TB, Curran T, LeBeau MM, Adamson ED. A zinc-finger encoding gene corregulated with c-fos during growth and differentiation and after depolarisation. Cell. 1988;53:37-43. [Medline] [Order article via Infotrieve]
23. Rupprecht HD, Dann P, Sukhatme VP, Sterzel RB, Colemann DL. Effect of vasoactive agents on induction of Egr-1: correlation with mitogenicity. Am J Physiol. 1992;265:F623-F636.
24. Schulze-Lohoff E, Bitzer M, Ogilvie A, Sterzel RB. Mitogenic effect of extracellular ATP on cultured mesangial cells: role of the metabolites adenosine, purine nucleosides and purine bases. Kidney Int. 1995;47:1000. Abstract.
25.
Hilderman RH, Martin M, Zimmerman JK, Pivorun
EB. Identification of a unique membrane receptor for
adenosine 5',5'''-P1,P4-tetraphosphate. J
Biol Chem. 1991;266:6915-6918.
26. Pintor J, Diaz-Rey MA, Miras-Portugal MT. Ap4A and ADP-ß-S binding to P2 purinoceptors present on rat brain synaptic terminals. Br J Pharmacol. 1993;108:1094-1099. [Medline] [Order article via Infotrieve]
27. Fredholm BB, Abbracchio MP, Burnstock G, Daly JW, Harden TK, Jacobson KA, Leff P, Williams M. Nomenclature and classification of purinoceptors. Pharmacol Rev. 1994;46:143-156. [Medline] [Order article via Infotrieve]
28. Walker J, Bossman P, Lackey JK, Zimmerman JK, Dimmick MA, Hilderman RH. The adenosine 5',5''', P1,P4-tetraphosphate receptor is at the cell surface of heart cells. Biochemistry. 1993;32:14009-14014. [Medline] [Order article via Infotrieve]
29. Varshavsky A. Diadenosine 5',5''',-P1,P4-tetraphosphate: a pleiotropic acting alarmone? Cell. 1983;34:711-712. [Medline] [Order article via Infotrieve]
30. Heidenreich S, Tepel M, Schlüter H, Harrach B, Zidek W. Regulation of rat mesangial cell growth by diadenosine phosphates. J Clin Invest. 1995;95:2862-2867.
31.
Dubyak GR, El-Moatassim C. Signal transduction
via P2-purinergic receptors for extracellular ATP and other
nucleotides. Am J Physiol. 1993;265:C577-C606.
32. Inscho EW, Mitchell KD, Navar LG. Extracellular ATP in the regulation of renal microvascular function. FASEB J. 1994;8:319-328. [Abstract]
33. Lüthje J, Ogilvie A. Catabolism of Ap4A and Ap3A in whole blood: the dinucleotides are long-lived signal molecules in blood ending up as intracellular ATP in erythrocytes. Eur J Biochem. 1988;173:241-247.[Medline] [Order article via Infotrieve]
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