1 Division of Nephrology, Department of Medicine, Kidney Research Center, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada K1H 8L6; and 2 Department of Medicine, Vanderbilt University, Nashville, Tennessee 37232
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ABSTRACT |
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Angiotensin IV
(ANG IV), the COOH-terminal hexapeptide fragment of angiotensin II (ANG
II), binds to specific sites in the kidney, distinct from type 1 (AT1) and type 2 (AT2) receptors and designated
type 4 (AT4) receptors. We determined signaling pathways
for ANG IV in a proximal tubular cell line,
LLC-PK1/Cl4. In these cells, we found no
specific binding of [125I]-ANG II. In contrast, ANG IV
dose dependently competed for [125I]-labeled ANG IV
binding, with no displacement by either ANG II, the AT1
receptor antagonist losartan, or the AT2 antagonist PD-123319. Saturation binding indicated the presence of AT4
receptors of high affinity [dissociation constant
(Kd) = 1.4 nM]. ANG IV did not affect cAMP
or cGMP production and did not increase cytosolic calcium concentration
in these cells. In contrast, immunoprecipitation and immunoblotting
studies revealed that ANG IV caused dose-dependent tyrosine
phosphorylation of p125-focal adhesion kinase (p125-FAK) and
p68-paxillin within 2 min, with maximal stimulation at 30 min. ANG
IV-stimulated tyrosine phosphorylation of p125-FAK and paxillin was not
affected by pretreatment with either losartan or PD-123319, and ANG II
(107 M) did not induce protein tyrosine phosphorylation.
Our results indicate that LLC-PK1/Cl4 cells
express ANG IV receptors, which we demonstrate for the first time are
linked to tyrosine phosphorylation of focal adhesion-associated
proteins. This suggests that ANG IV, a product of ANG II metabolism,
may regulate function of the focal adhesion complex in proximal tubule cells.
renin-angiotensin system; receptor; signaling; tyrosine kinase; renal proximal tubular epithelial cells
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INTRODUCTION |
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THE CLASSIC INTRARENAL FUNCTIONS of angiotensin II (ANG II) are primarily mediated by binding to G protein-coupled type 1 (AT1) receptors (43, 46), whereas the type 2 (AT2) receptors may be involved in natriuresis, growth inhibition, and apoptosis (19, 30, 50). In contrast, much less attention has been paid to the COOH-terminal 3-8 hexapeptide (Val-Tyr-Ile-His-Pro-Phe) fragment of ANG II, known as ANG IV, which is generated from successive cleavage of ANG II by aminopeptidases A and N, and potentially from ANG I-(3-10) by an angiotensin-converting enzyme (ACE)-dependent pathway (21, 48). Until 1992, ANG IV was believed to be an inactive metabolic fragment of ANG II, but in that year it was reported to possess biological activity in the central nervous system by interacting with distinct binding sites (29, 31, 42).
With the use of autoradiography and radioligand binding studies, specific receptors for ANG IV, termed AT4 receptors (29, 31, 42), have been detected in cerebral cortex, hippocampus, basal ganglia, cerebellum, and spinal cord, as well as in several peripheral tissues including kidney, bladder, heart, spleen, prostate, adrenal, and colon (48, 49). The function of AT4 receptors remains incompletely understood, although several lines of evidence suggest that ANG IV is an important regulator of blood flow. When infused into the renal artery, ANG IV increased endothelium-dependent renal cortical blood flow without altering systemic blood pressure (14, 42). Similarly, when added to pulmonary arterial rings, ANG IV caused endothelium-dependent vasorelaxation, which was linked to activation of nitric oxide (NO) synthase and generation of cGMP by pulmonary arterial endothelial cells (34), and when topically applied in the brain, ANG IV potentiated L-arginine-dependent vasodilation of rabbit cerebral arterioles (24). In contrast, ANG IV has also been reported to cause renal, mesenteric, and pulmonary vasoconstrictor effects that were inhibited by the AT1 receptor antagonist losartan (13, 20), suggesting that ANG IV is a weak agonist of AT1 receptors.
ANG IV may also regulate cell growth responses. ANG IV promotes cell growth in rabbit cardiac fibroblasts (47), bovine coronary endothelial cells (25), and rat anterior pituitary cells (35). Interestingly, Kakinuma et al. (32) reported an antiapoptotic role for ANG IV in neuronal cells, but the mechanism for this effect remains unclear.
The kidney expresses abundant AT4 receptors, localized to the proximal convoluted and straight tubules in the cortex and outer stripe of the outer medulla (28). In fresh suspensions of rat proximal tubules, ANG IV inhibits energy-dependent transcellular Na+ transport by direct activation of AT4 receptors (28), and, in an immortalized human proximal tubular cell line, ANG IV stimulates expression of plasminogen activator inhibitor-1 (23). The physiological functions of ANG IV in proximal tubule and the intracellular signaling mechanisms associated with AT4 receptors remain incompletely understood. Accordingly, in the present studies we utilized a well-characterized proximal tubule-like cell line, LLC-PK1/Cl4, to determine signaling responses mediated by ANG IV. Abundant, specific binding of ANG IV was detected in these cells, with no effect of ANG IV on cellular levels of cAMP, cGMP, calcium, or on DNA synthesis. However, ANG IV causes a significant stimulation of tyrosine phosphorylation of two focal adhesion-associated proteins, p125 focal adhesion kinase (p125-FAK), and paxillin.
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MATERIALS AND METHODS |
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Reagents and antibodies. 1:1 Bicarbonate-buffered mixture of DMEM and Ham's F-12 nutrient medium (DMEM/F-12) was purchased from GIBCO-BRL (Burlington, ON, Canada). ANG IV and ANG II were from Peninsula Laboratories (San Carios, CA). Losartan was generously provided by DuPont-Merck Pharmaceutical (Wilmington, DE), and PD-123319 was provided by Parke-Davis Pharmaceutical Research (Ann Arbor, MI). Fura 2-acetoxymethyl ester (fura 2-AM) and Pluronic-F127 were obtained from Molecular Probes, (Eugene, OR). Polyclonal and monoclonal (PY-20) anti-PY antibodies were purchased from Zymed Laboratories (San Francisco, CA). Monoclonal anti-paxillin and anti-FAK antibodies were from Transduction Laboratories (Lexington, KY). Polyclonal rabbit anti-FAK, anti-paxillin antibodies, and Protein A/G PLUS-Agarose beads were from Santa Cruz Biotechnology (Santa Cruz, CA). [125I]-labeled ANG IV (specific activity: 2,000 Ci/mmol), [125I]-labeled ANG II (specific activity: 2,200 Ci/mmol), the cGMP assay kit (containing [3H]cGMP), and enhanced chemiluminescence Hyperfilm were from Amersham Canada (Oakville, ON, Canada). The cAMP assay kit (containing [3H]cAMP) was from Intermedico, Markham, ON, Canada. All other chemicals were from Sigma (St. Louis, MO).
Cell culture. LLC-PK1/Cl4, an established proximal tubule epithelial cell line derived from pig kidney (1), was routinely cultured as previously described (11).
Ligand binding studies on cultured cells.
LLC-PK1/Cl4 cells were seeded at a density of
2 × 104 cells/well in 24-well plastic plates. The
cells were allowed to grow to subconfluence and made serum free
14-16 h before study. The cells were initially washed three times
with PBS supplemented with 0.1% BSA and then exposed to 0.1 nM
[125I]-ANG IV or [125I]-ANG II, in the
presence or absence of unlabeled ligands at selected concentrations, in
PBS-0.1% BSA containing EDTA (5 mM) and phenanthroline (1.25 mM) at
37°C for 1 h, followed by four washes with ice-cold PBS plus
0.1% BSA. After lysis in 0.05 M NaOH, cell-associated
radioactivity was measured in a gamma counter (Beckman 5500B). Specific
binding was determined by subtracting the nonspecific binding component
measured in the presence of 106 M unlabeled ANG IV or ANG
II from total [125I]-ANG IV or [125I]-ANG
II binding, respectively. To estimate maximal binding capacity and the
dissociation constant of AT4 receptors, saturation binding curves were generated by incubating the cells with increasing concentrations of [125I]-ANG IV (0.01-4 nM), in the
presence or absence of 10
6 M unlabeled ANG IV. Protein
concentration was measured with the Bio-Rad protein assay kit (Bio-Rad,
Montreal, Canada) according to the manufacturer's instructions.
Determination of cAMP and cGMP concentrations. LLC-PK1/Cl4 cells were grown to confluence on 24-well dishes and then incubated for 16 h in serum-free DMEM/F-12 medium. For assays of cAMP or cGMP, cells were incubated at 37°C for 15 min in DMEM/F-12, supplemented with the phosphodiesterase inhibitor, IBMX (0.5 mM) and 0.5% BSA, in the presence or absence of ANG IV or other agonists. Medium was then aspirated and replaced with ice-cold 10% TCA (vol/vol). After 30 min, samples were extracted four times with 4 vol of water-saturated ether and brought to pH 7 with Tris. Aliquots were assayed for cAMP or cGMP, using radioligand competitive binding assay kits, as we have performed (6, 7).
Measurements of cytosolic calcium concentration ([Ca2+]i) in LLC-PK1/Cl4 cells. Subconfluent cells grown on round glass coverslips were serum starved for 24 h and loaded for 45 min at 37°C with 5 µM fura 2-AM in the presence of 0.005% Pluronic-F127 in serum-free DMEM. The coverslip was mounted in a thermally controlled chamber and continuously perfused with a buffer containing (in mM) 105 NaCl, 24 NaHCO3, 5 KCl, 2 Na2HPO4, 1 MgSO4, 1.5 CaCl2, 4 lactic acid, 5 glucose, 1 alanine, and 10 HEPES (pH 7.3) as well as 0.2% BSA. Fluorescence was measured from dual monochromators set at 340 and 380 nm, using a computer-linked analytical system (Photon Technology International, South Brunswick, NJ), coupled to a Nikon Diaphot TMD-inverted fluorescence microscope equipped with a CF ×100 objective (Nikon, Tokyo, Japan). Single cells or clusters of two to three cells were studied with a ×100 oil-immersion lens. The emissions at the excitation wavelengths of 340 and 380 nm were collected by a photomultiplier at 510 nm and used to calculate the fluorescence ratio (R340/380), which was used as an indicator of [Ca2+]i.
[3H]thymidine incorporation assay. Subconfluent cells in 24-well plates were made quiescent with serum-free medium. Agents were routinely added to the quiescent cells in triplicate or duplicate and incubated for 16 h, followed by the addition of 2 µCi/ml of [3H]thymidine to pulse the cells for an additional 2 h. Cells were then washed five times with ice-cold PBS plus 0.5% BSA and incubated with ice-cold 10% TCA, twice for 30 min each time. The TCA precipitates were washed with ice-cold 100% ethanol and then lysed in 0.25 N NaOH-0.1% SDS, and DNA-incorporated thymidine was counted by liquid scintillation spectrometry (11). Results were plotted as the number of counts per minute per well. Each experimental data point represents the mean value from triplicate or duplicate wells.
Immunoprecipitation and immunoblotting. Immunoprecipitation and immunoblotting procedures were performed as previously described (10). Briefly, subconfluent LLC-PK1/Cl4 cells were made quiescent and treated with the indicated agents, washed twice with ice-cold Ca2+/Mg2+-free PBS, and lysed on ice for 30 min in a lysis buffer containing 0.5% Nonidet P-40, 50 mM NaCl, 10 mM Tris · HCl (pH 7.4), 2 mM EDTA, 2 mM EGTA, 0.5% sodium deoxycholate, 0.1% SDS, 100 µM Na3VO4, 100 mM NaF, 30 mM sodium pyrophosphate, 1 mM phenylmethylsulfonyl fluoride, 10 µg/ml aprotinin, and 10 µg/ml leupeptin. Cell lysates were clarified at 10,000 g for 15 min at 4°C, and protein concentrations were measured. Target proteins were immunoprecipitated at 4°C for 2 h with appropriate antibodies. Immune complexes were captured with Protein A/G PLUS-Agarose beads, washed four times with wash buffer, and eluted by boiling in sample buffer, as previously described (12).
Immunoprecipitates were subjected to 7-15% SDS-PAGE, transferred onto polyvinylidene difluoride membranes, probed with the indicated primary antibody and the appropriate secondary antibody conjugated with biotin, and incubated with preformed avidin-biotin-horseradish peroxidase complex using a commercially available kit (ABC kit; Intermedico, Markham, ON), and the immune complexes were detected by a peroxidase-catalyzed enhanced chemiluminescence detection system. Statistics. Data are presented as means ± SE for at least three separate experiments (each in triplicate or duplicate). Unpaired Student's t-test was used for statistical analysis. For multiple group comparisons, ANOVA and Bonferroni t-tests were used. A value of P < 0.05 was considered statistically significant. ![]() |
RESULTS |
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Binding studies.
In LLC-PK1/Cl4 cells at 37°C, ANG IV dose
dependently competed for [125I]-labeled ANG IV binding,
and 106 M ANG IV almost completely abolished
[125I]-labeled ANG IV binding (98.8% displacement) (Fig.
1A). In cells incubated with
[125I]-labeled ANG IV for 16 h at 4°C, unlabeled
ANG IV (10
6 M) still caused significant displacement of
binding (88.5 ± 1.3% displacement; n = 4). At
4°C, saturation of specific binding was observed after ~4 h.
Displacement binding experiments were performed further at 37°C to
determine the ligand specificity of the receptors. ANG II
(10
6-10
8 M) did not significantly displace
[125I]-ANG IV binding, and neither the AT1
receptor antagonist, losartan (10
5-10
7 M),
nor the AT2 receptor antagonist, PD-123319
(10
5-10
7 M) displaced
[125I]-ANG IV binding (Fig. 1A). There was
virtually no specific binding of [125I]-ANG II in these
cells (n = 6, data not shown).
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ANG IV does not increase [Ca2+]i in
LLC-PK1/Cl4 cells.
ANG IV has been shown to cause a transient rise in
[Ca2+]i in cultured opossum kidney cells
(17) and cultured rat mesangial cells (9),
and recently, Handa et al. (27) reported that ANG IV
induced a sustained elevation in [Ca2+]i in
Mardin-Darby bovine kidney epithelial cells. In fura 2-AM-loaded LLC-PK1/Cl4 cells, ANG IV had no effect on
[Ca2+]i, although exposure of the cells to
arginine vasopressin (AVP, 106 M), used as a positive
control, caused increases in [Ca2+]i
(Fig. 2).
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Effects of ANG IV on cAMP and cGMP levels in
LLC-PK1/Cl4 cells.
ANG IV has been shown to stimulate cAMP production by human
collecting duct cells in the presence of forskolin (15),
and Patel et al. (34) have shown that ANG IV increased
cGMP production in porcine pulmonary arterial endothelial cells. In
LLC-PK1/Cl4 cells, ANG IV had no significant
effect on either cAMP or cGMP levels, with positive controls (AVP for
cAMP, atrial natriuretic peptide, and sodium nitroprusside for cGMP)
demonstrating significant increases in levels of these second
messengers (Fig. 3).
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Effect of ANG IV on [3H]thymidine incorporation in
LLC-PK1/Cl4 cells.
It is well established that ANG II-induced activation of
AT1 receptors promotes proliferation in a number of cell
types (43, 46). In contrast, recent studies suggest that
AT2 receptors may inhibit cell growth, or cause
apoptosis (19). To characterize the potential
physiological roles of ANG IV in proximal tubule cells, we examined the
effect of ANG IV on DNA synthesis in
LLC-PK1/Cl4 cells. ANG IV (107 M)
did not stimulate [3H]thymidine incorporation in
quiescent cells (control: 11,104 ± 2,036 vs. ANG IV: 11,023 ± 1,950 dpm/well; n = 5, P = NS).
ANG IV induces protein tyrosine phosphorylation.
Protein tyrosine phosphorylation represents a common mechanism of
growth control in many cells. To examine if ANG IV could activate
protein tyrosine kinase cascades after binding to its AT4
receptor, confluent LLC-PK1/Cl4 cells were
rendered quiescent by incubation in serum-free medium for 72 h,
and then treated with ANG IV (107 M) for different time
periods. After solubilization, cell lysates were subjected to
immunoprecipitation with polyclonal anti-phosphotyrosine (PY) and
immunoblotting with monoclonal anti-phosphotyrosine (PY-20). Administration of ANG IV stimulated marked increases in tyrosine phosphorylation of several proteins, with two predominant bands, one at
~125 kDa, and the other at ~68 kDa. This effect was observed within
2 min, and peaked at 30 min after exposure to 10
7 M ANG
IV (Fig. 4).
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DISCUSSION |
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Specific binding sites for ANG IV have been identified in several mammalian tissues, including brain, spinal cord, colon, heart, lung, bladder, adrenal gland, and kidney, often by [125I]-ANG IV binding assays on isolated cell membranes (29, 31, 34). In the present study, we performed [125I]-ANG IV binding in intact LLC-PK1/Cl4 cells, a porcine renal proximal tubule cell line expressing no detectable ANG II AT1 and AT2 receptors (3, 6), and identified the presence of AT4 receptors of high affinity, with high specificity for ANG IV. Our data do not exclude the possibility of receptor subtypes for ANG IV in these cells of uniform affinity. These receptors have a maximal amount of binding sites of 609.6 fmol/mg of cellular proteins, reflecting a high concentration of AT4 receptors in these cells. Therefore, this is an ideal cell model to investigate the potential physiological functions and mechanisms of action of ANG IV.
To study AT4 receptor-mediated intracellular signaling mechanisms in these cells, we examined a number of classical second messengers. Our results indicate that ANG IV had no effect on [Ca2+]i or on intracellular levels of cAMP or cGMP in these cells. In certain tissues, ligand binding to plasma membrane AT4 receptors has been shown to increase [Ca2+]i (16, 17, 27). Enhanced cAMP production (15), and elevated nitric oxide synthase activity leading to increased cGMP production, have also been reported to be induced by AT4 receptor activation (34). This suggests that after ANG IV binding, activation of AT4 receptors initiates intracellular signaling events in a cell type- or species-specific fashion. This notion is supported by the observation that ANG IV did not exert any effect on [Ca2+]i in embryonic chick cardiac myocytes (2) or neuroblastoma cells (36), and ANG IV did not alter either [Ca2+]i or cGMP production in human collecting duct cells (15). Similarly, ANG IV had no effect on [Ca2+]i or cAMP production in bovine aortic endothelial cells (5). Although our data revealed no significant effect of ANG IV on DNA synthesis in LLC-PK1/Cl4 cells, a cell growth-promoting effect of ANG IV has been observed in other cell types (25, 35, 47), although the mitogenic signaling mechanisms of ANG IV remain undefined.
Protein tyrosine phosphorylation by activation of tyrosine kinases is
one of the most common and important regulatory mechanisms in signal
transmission. Accordingly, we examined the possibility that
AT4 receptors might be linked to tyrosine kinase
phosphorylation pathways. The present studies are the first
demonstration that binding of ANG IV to its AT4 receptor
stimulates marked increases in tyrosine phosphorylation of the focal
adhesion-associated proteins, p125-FAK and paxillin, in a time- and
concentration-dependent manner. In the radioligand binding studies,
107 M ANG IV almost completely abolished
[125I]-labeled ANG IV binding, and ANG IV-stimulated
tyrosine phosphorylation was detectable at 10
9 M, and
reached a maximum at 10
7 M, with no additional
stimulation at 10
6 M. This effect of ANG IV was not
altered by the AT1 receptor antagonist, losartan or the
AT2 receptor antagonist, PD-123319. In addition, the
precursor of ANG IV, ANG II, had no significant effect on tyrosine
phosphorylation of either p125-FAK or paxillin, and, indeed, there was
no specific binding of [125I]-ANG II in these cells.
Together, these results indicate that ANG IV induces tyrosine
phosphorylation of these two focal adhesion-associated proteins via
functional coupling to specific AT4 receptors.
Our study did not focus on the upstream or downstream signaling pathways of p125-FAK or paxillin in the ANG IV-induced tyrosine kinase cascade in LLC-PK1/Cl4 cells. In this regard, p125-FAK and paxillin have been shown to colocalize with integrins, transmembrane receptors that engage extracellular matrix ligands such as fibronectin, to the focal adhesion complex, where p125-FAK plays a central role in the regulation of cell signaling, proliferation, apoptosis, migration, spreading, and oncogenic transformation (8, 41). p125-FAK associates with a number of signaling and cytoskeletal molecules, including Src kinases, PI 3-kinase, Shc, Grb2, p130Cas (crk-associated substrate), talin, and paxillin (41). On integrin-dependent cell adhesion, p125-FAK becomes autophosphorylated on Tyr-397, creating a high affinity Src SH2-binding site, and becomes enzymatically activated (18, 38). On binding to Tyr-397 of p125-FAK, Src can phosphorylate p125-FAK on a number of additional tyrosine residues, thereby resulting in enhanced catalytic activity of p125-FAK and inducing the formation of docking sites on p125-FAK for additional SH2-containing binding partners, such as Grb2 (40). Formation of the p125-FAK-Src complex can direct tyrosine phosphorylation of additional focal adhesion-associated substrates such as paxillin and p130Cas, which results in the recruitment of additional SH2 domain-containing signaling molecules such as Crk (39, 41). Thus Src acts upstream of p125-FAK and plays an essential role in p125-FAK tyrosine phosphorylation of paxillin and p130Cas in these complexes. In addition, although its predominant role is in integrin signal transduction, p125-FAK is also tyrosine phosphorylated in response to a variety of other extracellular stimuli that act either on specific membrane receptors or on intracellular signaling molecules, such as protein kinase C or Rho (8, 37, 41), and initiation of the Ras/mitogen-activated protein kinase pathway has been suggested to be a downstream signaling event of p125-FAK activation (40, 41). Therefore, it is reasonable to speculate that binding of ANG IV to AT4 receptors in LLC-PK1/Cl4 cells might activate Src kinases and induce p125-FAK tyrosine phosphorylation, which then leads to tyrosine phosphorylation of paxillin, as well as extracellular signal-related kinase. Phosphorylation of p125-FAK and paxillin by ANG IV also suggests the possibility that ANG IV might influence a range of physiological parameters in proximal tubule cells, including cell adhesion, cell spreading, and cell motility.
Further studies characterizing the structure of the AT4
receptor should provide insight into these signaling pathways and the
biological effects of ANG IV. In this regard, it has been suggested
that unlike the AT1 or AT2 receptor, the
AT4 receptor is not a G protein-coupled receptor, because
guanosine 5'-O-(3-thiotriphosphate)S and polyvinyl
sulfate do not affect [125I]-ANG IV binding (4,
27). Cross-linking and photoaffinity-labeling studies
suggest that the AT4 receptor is a ~165-186 kDa
integral membrane glycoprotein with a very large extracellular domain, a single transmembrane domain, and a short intracellular tail (4,
5, 51). These properties, together with our demonstration of
activation of tyrosine phosphorylation pathways, suggest that the
AT4 receptor may be a member of the family of growth factor or cytokine receptors, which includes receptors for epidermal growth
factor (45), interleukin-11 (33), and
granulocyte-macrophage colony-stimulating factor (22).
The generation of ANG IV has been thought to occur via successive cleavage of ANG II by aminopeptidases A and N. Recently, a novel human zinc metalloprotease has been cloned, representing a homolog of ACE (44). This novel protein is highly expressed in kidney, heart, and testis and acts as a carboxypeptidase to cleave the COOH-terminal residues from ANG I and ANG II, forming ANG-(1-9) and ANG-(1-7), respectively. The role of this enzyme in regulating production of ANG IV in the proximal tubule remains to be clarified. Furthermore, the possibility of functional coupling of other locally generated peptide fragments to ANG IV receptors requires further study. In this regard, ANG-(1-7) has been shown to bind to ANG IV receptors in proximal tubule cells (26), although effects on protein tyrosine phosphorylation have not been reported.
In summary, we have demonstrated that LLC-PK1/Cl4 cells express functional AT4 receptors of uniform high affinity, and ligand-dependent activation of these receptors induces tyrosine phosphorylation of focal adhesion-associated proteins. The present studies suggest that in addition to activation of AT1 or AT2 receptors, ANG II may modulate function of the focal adhesion complex by metabolism to ANG IV and activation of AT4 receptors.
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ACKNOWLEDGEMENTS |
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This work was supported by a grant from the Kidney Foundation of Canada (to K. D. Burns).
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FOOTNOTES |
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Address for reprint requests and other correspondence: K. D. Burns, Div. of Nephrology, Univ. of Ottawa and The Ottawa Hospital, 501 Smyth Rd., Rm. LM-18, Ottawa, Ontario, Canada K1H 8L6 (E-mail: kburns{at}ottawahospital.on.ca).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Received 28 September 2000; accepted in final form 26 January 2001.
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REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1.
Amsler, K,
and
Cook JS.
Development of Na+-dependent hexose transport in a cultured line of porcine kidney cells.
Am J Physiol Cell Physiol
242:
C94-C101,
1982
2.
Baker, KM,
and
Aceto JF.
Angiotensin II stimulation of protein synthesis and cell growth in chick heart cells.
Am J Physiol Heart Circ Physiol
259:
H610-H618,
1990
3.
Becker, BN,
Kondo S,
Chen JK,
and
Harris RC.
Tyrosine kinase inhibition affects type 1 angiotensin II receptor internalization.
J Recept Signal Transduct Res
19:
975-993,
1999[ISI][Medline].
4.
Bernier, SG,
Bellemare JM,
Escher E,
and
Guillemette G.
Characterization of AT4 receptor from bovine aortic endothelium with photosensitive analogues of angiotensin IV.
Biochemistry
37:
4280-4287,
1998[ISI][Medline].
5.
Briand, SI,
Bellemare JM,
Bernier SG,
and
Guillemette G.
Study on the functionality and molecular properties of the AT4 receptor.
Endocr Res
24:
315-323,
1998[ISI][Medline].
6.
Burns, KD,
and
Harris RC.
Signaling and growth responses of LLC-PK1/Cl4 cells transfected with the rabbit AT1 ANG II receptor.
Am J Physiol Cell Physiol
268:
C925-C935,
1995
7.
Burns, KD,
Regnier L,
Roczniak A,
and
Hebert RL.
Immortalized rabbit cortical collecting duct cells express AT1 angiotensin II receptors.
Am J Physiol Renal Fluid Electrolyte Physiol
271:
F1147-F1157,
1996
8.
Cary, LA,
and
Guan JL.
Focal adhesion kinase in integrin-mediated signaling.
Front Biosci
4:
D102-D113,
1999[Medline].
9.
Chansel, D,
Czekalski S,
Vandermeersch S,
Ruffet E,
Fournie-Zaluski MC,
and
Ardaillou R.
Characterization of angiotensin IV-degrading enzymes and receptors on rat mesangial cells.
Am J Physiol Renal Physiol
275:
F535-F542,
1998
10.
Chen, JK,
Capdevila J,
and
Harris RC.
Overexpression of C-terminal Src kinase blocks 14,15-epoxyeicosatrienoic acid-induced tyrosine phosphorylation and mitogenesis.
J Biol Chem
275:
13789-13792,
2000
11.
Chen, JK,
Falck JR,
Reddy KM,
Capdevila J,
and
Harris RC.
Epoxyeicosatrienoic acids and their sulfonimide derivatives stimulate tyrosine phosphorylation and induce mitogenesis in renal epithelial cells.
J Biol Chem
273:
29254-29261,
1998
12.
Chen, JK,
Wang DW,
Falck JR,
Capdevila J,
and
Harris RC.
Transfection of an active cytochrome P-450 arachidonic acid epoxygenase indicates that 14,15-epoxyeicosatrienoic acid functions as an intracellular second messenger in response to epidermal growth factor.
J Biol Chem
274:
4764-4769,
1999
13.
Cheng, DY,
DeWitt BJ,
Dent EL,
Nossaman BD,
and
Kadowitz PJ.
Analysis of responses to angiotensin IV in the pulmonary vascular bed of the cat.
Eur J Pharmacol
261:
223-227,
1994[ISI][Medline].
14.
Coleman, JK,
Krebs LT,
Hamilton TA,
Ong B,
Lawrence KA,
Sardinia MF,
Harding JW,
and
Wright JW.
Autoradiographic identification of kidney angiotensin IV binding sites and angiotensin IV-induced renal cortical blood flow changes in rats.
Peptides
19:
269-277,
1998[ISI][Medline].
15.
Czekalski, S,
Chansel D,
Vandermeersch S,
Ronco P,
and
Ardaillou R.
Evidence for angiotensin IV receptors in human collecting duct cells.
Kidney Int
50:
1125-1131,
1996[ISI][Medline].
16.
Dostal, DE,
Murahashi T,
and
Peach MJ.
Regulation of cytosolic calcium by angiotensins in vascular smooth muscle.
Hypertension
15:
815-822,
1990[Abstract].
17.
Dulin, N,
Madhun ZT,
Chang CH,
Berti-Mattera L,
Dickens D,
and
Douglas JG.
Angiotensin IV receptors and signaling in opossum kidney cells.
Am J Physiol Renal Fluid Electrolyte Physiol
269:
F644-F652,
1995
18.
Eide, BL,
Turck CW,
and
Escobedo JA.
Identification of Tyr-397 as the primary site of tyrosine phosphorylation and pp60src association in the focal adhesion kinase, pp125FAK.
Mol Cell Biol
15:
2819-2827,
1995[Abstract].
19.
Gallinat, S,
Busche S,
Raizada MK,
and
Sumners C.
The angiotensin II type 2 receptor: an enigma with multiple variations.
Am J Physiol Endocrinol Metab
278:
E357-E374,
2000
20.
Gardiner, SM,
Kemp PA,
March JE,
and
Bennett T.
Regional haemodynamic effects of angiotensin II (3-8) in conscious rats.
Br J Pharmacol
110:
159-162,
1993[Abstract].
21.
Garrison, EA,
and
Kadowitz PJ.
Analysis of responses to angiotensin I-(3-10) in the hindlimb vascular bed of the cat.
Am J Physiol Heart Circ Physiol
270:
H1172-H1177,
1996
22.
Gearing, DP,
King JA,
Gough NM,
and
Nicola NA.
Expression cloning of a receptor for human granulocyte-macrophage colony-stimulating factor.
EMBO J
8:
3667-3676,
1989[Abstract].
23.
Gesualdo, L,
Ranieri E,
Monno R,
Rossiello MR,
Colucci M,
Semeraro N,
Grandaliano G,
Schena FP,
Ursi M,
and
Cerullo G.
Angiotensin IV stimulates plasminogen activator inhibitor-1 expression in proximal tubular epithelial cells.
Kidney Int
56:
461-470,
1999[ISI][Medline].
24.
Haberl, RL,
Decker PJ,
and
Einhaupl KM.
Angiotensin degradation products mediate endothelium-dependent dilation of rabbit brain arterioles.
Circ Res
68:
1621-1627,
1991[Abstract].
25.
Hall, KL,
Venkateswaran S,
Hanesworth JM,
Schelling ME,
and
Harding JW.
Characterization of a functional angiotensin IV receptor on coronary microvascular endothelial cells.
Regul Pept
58:
107-115,
1995[ISI][Medline].
26.
Handa, RK.
Angiotensin-(1-7) can interact with the rat proximal tubule AT(4) receptor system.
Am J Physiol Renal Physiol
277:
F75-F83,
1999
27.
Handa, RK,
Harding JW,
and
Simasko SM.
Characterization and function of the bovine kidney epithelial angiotensin receptor subtype 4 using angiotensin IV and divalinal angiotensin IV as receptor ligands.
J Pharmacol Exp Ther
291:
1242-1249,
1999
28.
Handa, RK,
Krebs LT,
Harding JW,
and
Handa SE.
Angiotensin IV AT4-receptor system in the rat kidney.
Am J Physiol Renal Physiol
274:
F290-F299,
1998
29.
Harding, JW,
Cook VI,
Miller-Wing AV,
Hanesworth JM,
Sardinia MF,
Hall KL,
Stobb JW,
Swanson GN,
Coleman JK,
Wright JW,
and
Harding EC.
Identification of an AII(3-8) [AIV] binding site in guinea pig hippocampus.
Brain Res
583:
340-343,
1992[ISI][Medline].
30.
Horiuchi, M,
Hayashida W,
Kambe T,
Yamada T,
and
Dzau VJ.
Angiotensin type 2 receptor dephosphorylates Bcl-2 by activating mitogen-activated protein kinase phosphatase-1 and induces apoptosis.
J Biol Chem
272:
19022-19026,
1997
31.
Jarvis, MF,
Gessner GW,
and
Ly CQ.
The angiotensin hexapeptide 3-8 fragment potently inhibits [125I] angiotensin II binding to non-AT1 or -AT2 recognition sites in bovine adrenal cortex.
Eur J Pharmacol
219:
319-322,
1992[ISI][Medline].
32.
Kakinuma, Y,
Hama H,
Sugiyama F,
Goto K,
Murakami K,
and
Fukamizu A.
Anti-apoptotic action of angiotensin fragments to neuronal cells from angiotensinogen knock-out mice.
Neurosci Lett
232:
167-170,
1997[ISI][Medline].
33.
Nandurkar, HH,
Hilton DJ,
Nathan P,
Willson T,
Nicola N,
and
Begley CG.
The human IL-11 receptor requires gp130 for signalling: demonstration by molecular cloning of the receptor.
Oncogene
12:
585-593,
1996[ISI][Medline].
34.
Patel, JM,
Martens JR,
Li YD,
Gelband CH,
Raizada MK,
and
Block ER.
Angiotensin IV receptor-mediated activation of lung endothelial NOS is associated with vasorelaxation.
Am J Physiol Lung Cell Mol Physiol
275:
L1061-L1068,
1998
35.
Pawlikowski, M,
and
Kunert-Radek J.
Angiotensin IV stimulates the proliferation of rat anterior pituitary cells in vitro.
Biochem Biophys Res Commun
232:
292-293,
1997[ISI][Medline].
36.
Ransom, JT,
Sharif NA,
Dunne JF,
Momiyama M,
and
Melching G.
AT1 angiotensin receptors mobilize intracellular calcium in a subclone of NG108-15 neuroblastoma cells.
J Neurochem
58:
1883-1888,
1992[ISI][Medline].
37.
Rodriguez-Fernandez, JL.
Why do so many stimuli induce tyrosine phosphorylation of FAK?
Bioessays
21:
1069-1075,
1999[ISI][Medline].
38.
Schaller, MD,
Hildebrand JD,
Shannon JD,
Fox JW,
Vines RR,
and
Parsons JT.
Autophosphorylation of the focal adhesion kinase, pp125FAK, directs SH2-dependent binding of pp60src.
Mol Cell Biol
14:
1680-1688,
1994[Abstract].
39.
Schaller, MD,
and
Parsons JT.
pp125FAK-dependent tyrosine phosphorylation of paxillin creates a high-affinity binding site for Crk.
Mol Cell Biol
15:
2635-2645,
1995[Abstract].
40.
Schlaepfer, DD,
Hanks SK,
Hunter T,
and
van der Geer P.
Integrin-mediated signal transduction linked to Ras pathway by GRB2 binding to focal adhesion kinase.
Nature
372:
786-791,
1994[ISI][Medline].
41.
Schlaepfer, DD,
Hauck CR,
and
Sieg DJ.
Signaling through focal adhesion kinase.
Prog Biophys Mol Biol
71:
435-478,
1999[ISI][Medline].
42.
Swanson, GN,
Hanesworth JM,
Sardinia MF,
Coleman JK,
Wright JW,
Hall KL,
Miller-Wing AV,
Stobb JW,
Cook VI,
Harding EC,
and
Harding JW.
Discovery of a distinct binding site for angiotensin II (3-8), a putative angiotensin IV receptor.
Regul Pept
40:
409-419,
1992[ISI][Medline].
43.
Timmermans, PB,
Wong PC,
Chiu AT,
Herblin WF,
Benfield P,
Carini DJ,
Lee RJ,
Wexler RR,
Saye JA,
and
Smith RD.
Angiotensin II receptors and angiotensin II receptor antagonists.
Pharmacol Rev
45:
205-251,
1993[ISI][Medline].
44.
Tipnis, SR,
Hooper NM,
Hyde R,
Karran E,
Christie G,
and
Turner AJ.
A human homologue of angiotensin-converting enzyme. Cloning and functional expression as a captopril-insensitive carboxypeptidase.
J Biol Chem
275:
33238-33243,
2000
45.
Ullrich, A,
Coussens L,
Hayflick JS,
Dull TJ,
Gray A,
Tam AW,
Lee J,
Yarden Y,
Libermann TA,
Schlessinger J,
Downward J,
Mayes ELV,
Whittle N,
Waterfield MD,
and
Seeburg PH.
Human epidermal growth factor receptor cDNA sequence and aberrant expression of the amplified gene in A431 epidermoid carcinoma cells.
Nature
309:
418-425,
1984[ISI][Medline].
46.
Unger, T,
Chung O,
Csikos T,
Culman J,
Gallinat S,
Gohlke P,
Hohle S,
Meffert S,
Stoll M,
Stroth U,
and
Zhu YZ.
Angiotensin receptors.
J Hypertens Suppl
14:
S95-S103,
1996[Medline].
47.
Wang, L,
Eberhard M,
and
Erne P.
Stimulation of DNA and RNA synthesis in cultured rabbit cardiac fibroblasts by angiotensin IV.
Clin Sci (Colch)
88:
557-562,
1995[ISI][Medline].
48.
Wright, JW,
Krebs LT,
Stobb JW,
and
Harding JW.
The angiotensin IV system: functional implications.
Front Neuroendocrinol
16:
23-52,
1995[ISI][Medline].
49.
Wright, JW,
Miller-Wing AV,
Shaffer MJ,
Higginson C,
Wright DE,
Hanesworth JM,
and
Harding JW.
Angiotensin II(3-8) (ANG IV) hippocampal binding: potential role in the facilitation of memory.
Brain Res Bull
32:
497-502,
1993[ISI][Medline].
50.
Yamada, T,
Horiuchi M,
and
Dzau VJ.
Angiotensin II type 2 receptor mediates programmed cell death.
Proc Natl Acad Sci USA
93:
156-160,
1996
51.
Zhang, JH,
Stobb JW,
Hanesworth JM,
Sardinia MF,
and
Harding JW.
Characterization and purification of the bovine adrenal angiotensin IV receptor (AT4) using [125I]benzoylphenylalanine-angiotensin IV as a specific photolabel.
J Pharmacol Exp Ther
287:
416-424,
1998