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Shashar M, Zubkov A, Chernichovski T, Hershkovitz R, Hoffman E, Grupper A, Weinstein T, Schwartz IF. Profound Decrease in Glomerular Arginine Transport by CAT (Cationic Amino Acid Transporter)-1 Contributes to the FLT-1 (FMS-Like Tyrosine Kinase 1) Induced Preeclampsia in the Pregnant Mice. Hypertension 2019; 73:878-884. [PMID: 30798662 DOI: 10.1161/hypertensionaha.118.12372] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Endothelial dysfunction because of nitric oxide inactivation has been suggested to play a role in the pathogenesis of preeclampsia. During pregnancy, L-arginine transport by CAT-1 (cationic amino acid transporter 1), the only transporter for eNOS (endothelial nitric oxide synthase) is inhibited. We hypothesize that maternal arginine deficiency contributes to the development of preeclampsia. Adenovirus-mediated overexpression of sFlt-1 (soluble fms-like tyrosine kinase 1) in virgin and pregnant mice resulted in glomerular endotheliosis, hypertension, and albuminuria. L-arginine prevented the increase in blood pressure and albuminuria in Flt-1 pregnant but not in Flt-1 virgin mice. Flt-1 augmented arginine transport in pregnant but not in virgin dames. Ex vivo inhibition of CAT-2 leaving exclusively CAT-1 activity, decreased arginine transport velocities in Flt-1 animals more prominently in pregnant dames. Phosphorylated CAT-1/CAT-1 increased in pregnant, sFlt-1-pregnant, and sFlt-1 virgin mice. CAT-2 increased in Flt-1-pregnant and Flt-1-virgin dames. L-arginine augmented arginine transport in pregnant and Flt-pregnant mice and prevented the increase in pCAT-1 and CAT-2 expression. Glomerular cGMP (cyclic guanosine monophosphate) generation as a measure of eNOS activity was decreased in all Flt-1 treated animals. L-arginine abolished the decrease in cGMP levels only in Flt-1-pregnant mice. In conclusion, glomerular endothelial NO generation is compromised in Flt-1-pregnant mice because of CAT-1 inhibition induced by a combined effect of pregnancy and preeclampsia which involves: phosphorylation of CAT-1 and induction of CAT-2. These processes contribute to the clinical syndrome of preeclampsia in mice and are prevented by L-arginine.
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Affiliation(s)
- Moshe Shashar
- From the Departments of Nephrology (M.S., T.C., E.H., A.G., T.W., I.F.S.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Asia Zubkov
- Pathology (A.Z.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Tamara Chernichovski
- From the Departments of Nephrology (M.S., T.C., E.H., A.G., T.W., I.F.S.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Rami Hershkovitz
- Internal Medicine "T" (R.H., I.F.S.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Elinoar Hoffman
- From the Departments of Nephrology (M.S., T.C., E.H., A.G., T.W., I.F.S.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Ayelet Grupper
- From the Departments of Nephrology (M.S., T.C., E.H., A.G., T.W., I.F.S.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Talia Weinstein
- From the Departments of Nephrology (M.S., T.C., E.H., A.G., T.W., I.F.S.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Idit F Schwartz
- From the Departments of Nephrology (M.S., T.C., E.H., A.G., T.W., I.F.S.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel.,Internal Medicine "T" (R.H., I.F.S.), Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
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Shashar M, Hod T, Chernichovski T, Angel A, Kazan S, Grupper A, Naveh S, Kliuk-Ben Bassat O, Weinstein T, Schwartz IF. Mineralocorticoid receptor blockade improves arginine transport and nitric oxide generation through modulation of cationic amino acid transporter-1 in endothelial cells. Nitric Oxide 2018; 80:24-31. [PMID: 30056252 DOI: 10.1016/j.niox.2018.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 07/12/2018] [Accepted: 07/25/2018] [Indexed: 11/27/2022]
Abstract
Blockade of the mineralocorticoid receptor (MCR) has been shown to improve endothelial function far beyond blood pressure control. In the current studies we have looked at the effect of MCR antagonists on cationic amino acid transporter-1 (CAT-1), a major modulator of endothelial nitric oxide (NO) generation. Using radio-labeled arginine, {[3H] l-arginine} uptake was determined in human umbilical vein endothelial cells (HUVEC) following incubation with either spironolactone or eplerenone with or without silencing of MCR. Western blotting for CAT-1, PKCα and their phosphorylated forms were performed. NO generation was measured by using Griess reaction assay. Both Spironolactone and eplerenone significantly increased endothelial arginine transport, an effect which was further augmented by co-incubation with aldosterone, and blunted by either silencing of MCR or co-administration of amiloride. Following MCR blockade, we identified two bands for CAT-1. The addition of tunicamycin (an inhibitor of protein glycosylation) or MCR silencing resulted in disappearance of the extra band and prevented the increase in arginine transport. Only spironolactone decreased CAT-1 phosphorylation through inhibition of PKCα (CAT-1 inhibitor). Subsequently, incubation with either MCR antagonists significantly augmented NO2/NO3 levels (stable NO metabolites) and this was attenuated by silencing of MCR or tunicamycin. GO 6076 (PKCα inhibitor) intensified the increase of NO metabolites only in eplerenone treated cells. In conclusion spironolactone and eplerenone augment arginine transport and NO generation through modulation of CAT-1 in endothelial cells. Both MCR antagonists activate CAT-1 by inducing its glycosylation while only spironolactone inhibits PKCα.
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Affiliation(s)
- Moshe Shashar
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel; Nephrology Section, Sanz Medical Center, Laniado Hospital, Netanya, Israel
| | - Tamar Hod
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
| | - Tamara Chernichovski
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
| | - Avital Angel
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
| | - Shaul Kazan
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
| | - Ayelet Grupper
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
| | - Sivan Naveh
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
| | - Orit Kliuk-Ben Bassat
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
| | - Talia Weinstein
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
| | - Idit F Schwartz
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel.
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Shashar M, Chernichovski T, Pasvolsky O, Levi S, Grupper A, Hershkovitz R, Weinstein T, Schwartz IF. Vascular Endothelial Growth Factor Augments Arginine Transport and Nitric Oxide Generation via a KDR Receptor Signaling Pathway. Kidney Blood Press Res 2017; 42:201-208. [PMID: 28478454 DOI: 10.1159/000476016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 01/17/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Vascular endothelial growth factor (VEGF) is an endothelium-specific peptide that stimulates angiogenesis via two receptor tyrosine kinases, Flt-1 and KDR. Endothelial nitric oxide synthase (eNOS) plays a major role in VEGF signaling. Delivery of arginine to membrane bound eNOS by the cationic amino acid transporter-1 (CAT-1) has been shown to modulate eNOS activity. The current studies were designed to test the hypothesis that VEGF enhances eNOS activity via modulation of arginine transport by CAT-1. METHODS Using radio-labeled arginine, {[3H] L-arginine} uptake was determined in human umbilical vein endothelial cells (HUVEC) following incubation with VEGF with and without silencing the VEGF receptors Flt-1 or KDR. Subsequently, western blotting for CAT-1, PKCα, ERK 1/2, JNK, and their phosphorylated forms were performed. NO generation was measured by the Griess reaction. RESULTS VEGF (50 and 100 ng/ml) significantly augmented endothelial arginine transport in a time dependent manner, an effect which was prevented by Sunitinib (2 µM), a multi targeted receptor tyrosine kinase inhibitor. The increase in arginine transport velocities by VEGF was not affected by silencing Flt-1 while silencing KDR abrogated VEGF effect. Furthermore, incubating cells with 50 and 100 ng of VEGF for 30 minutes significantly augmented CAT-1 abundance. The expression of PKC-α, JNK, and ERK1/2 and their phosphorylated forms were unchanged following incubation of HUVEC with VEGF. The concentration of NO2/NO3 following incubation with VEGF was significantly higher than from untreated cells. This increase was significantly attenuated by silencing KDR. CONCLUSIONS VEGF increases arginine transport via modulation of CAT-1 in endothelial cells. This effect is exclusively dependent on KDR rather than Flt-1.
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Dimethyl sulfoxide attenuates nitric oxide generation via modulation of cationic amino acid transporter-1 in human umbilical vein endothelial cells. Cryobiology 2016; 73:226-31. [DOI: 10.1016/j.cryobiol.2016.07.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 07/02/2016] [Accepted: 07/05/2016] [Indexed: 11/18/2022]
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Bentur OS, Schwartz D, Chernichovski T, Ingbir M, Weinstein T, Chernin G, Schwartz IF. Estradiol augments while progesterone inhibits arginine transport in human endothelial cells through modulation of cationic amino acid transporter-1. Am J Physiol Regul Integr Comp Physiol 2015; 309:R421-7. [PMID: 26062636 DOI: 10.1152/ajpregu.00532.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Accepted: 06/04/2015] [Indexed: 01/03/2023]
Abstract
Decreased generation of nitric oxide (NO) by endothelial NO synthase (eNOS) characterizes endothelial dysfunction (ECD). Delivery of arginine to eNOS by cationic amino acid transporter-1 (CAT-1) was shown to modulate eNOS activity. We found in female rats, but not in males, that CAT-1 activity is preserved with age and in chronic renal failure, two experimental models of ECD. In contrast, during pregnancy CAT-1 is inhibited. We hypothesize that female sex hormones regulate arginine transport. Arginine uptake in human umbilical vein endothelial cells (HUVEC) was determined following incubation with either 17β-estradiol (E2) or progesterone. Exposure to E2 (50 and 100 nM) for 30 min resulted in a significant increase in arginine transport and reduction in phosphorylated CAT-1 (the inactive form) protein content. This was coupled with a decrease in phosphorylated MAPK/extracellular signal-regulated kinase (ERK) 1/2. Progesterone (1 and 100 pM for 30 min) attenuated arginine uptake and increased phosphorylated CAT-1, phosphorylated protein kinase Cα (PKCα), and phosphorylated ERK1/2 protein content. GO-6976 (PKCα inhibitor) prevented the progesterone-induced decrease in arginine transport. Coincubation with both progesterone and estrogen for 30 min resulted in attenuated arginine transport. While estradiol increases arginine transport and CAT-1 activity through modulation of constitutive signaling transduction pathways involving ERK, progesterone inhibits arginine transport and CAT-1 via both PKCα and ERK1/2 phosphorylation, an effect that predominates over estradiol.
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Affiliation(s)
- Ohad S Bentur
- Department of Nephrology, Sackler School of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Doron Schwartz
- Department of Nephrology, Sackler School of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Tamara Chernichovski
- Department of Nephrology, Sackler School of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Merav Ingbir
- Department of Nephrology, Sackler School of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Talia Weinstein
- Department of Nephrology, Sackler School of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Gil Chernin
- Department of Nephrology, Sackler School of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Idit F Schwartz
- Department of Nephrology, Sackler School of Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
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Grupper A, Shashar M, Bahry D, Pri-Paz Y, Ben Tur O, Levi S, Chernichovski T, Chernin G, Schwartz IF. Cyclosporine attenuates arginine transport, in human endothelial cells, through modulation of cationic amino acid transporter-1. Am J Nephrol 2013; 37:613-9. [PMID: 23796541 DOI: 10.1159/000350614] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 03/10/2013] [Indexed: 11/19/2022]
Abstract
BACKGROUND The spectrum of cardiovascular toxicity by cyclosporine (CsA) includes hypertension, accelerated atherosclerosis, and thrombotic microangiopathy, all of which are the result of endothelial cell dysfunction. Endothelial cell dysfunction is characterized by decreased endothelial nitric oxide synthase (eNOS) activity. Cationic amino acid transporter-1 (CAT-1) is the specific arginine transporter for eNOS. CsA has been shown to attenuate nitric oxide (NO) generation. However, the mechanism remains elusive. We hypothesize that CsA inhibits eNOS activity through modulation of its selective arginine supplier CAT-1. METHODS We studied the effect of CsA on arginine uptake, NO2/NO3 generation, and CAT-1, protein kinase Cα (PKCα), and phosphorylated PKCα protein expression in human umbilical vein endothelial cell cultures (HUVEC) in the absence and presence of L-arginine. RESULTS CsA (0.5-2 μg/ml) significantly attenuated arginine transport in a dose- and time-dependent manner, a phenomenon which was prevented by co-incubation with L-arginine (1 mM). The aforementioned findings were accompanied by increased protein nitration, a measure for peroxynitrite accumulation. In contrast, no changes were observed in NO2/NO3 generation. CsA significantly decreased the abundance of CAT-1 protein, an effect that was attenuated by L-arginine. PKCα and phosphorylated PKCα (CAT-1 inhibitors) protein contents were not affected by CsA. CONCLUSION CsA inhibits arginine transport and induces protein nitration in HUVEC through modulation of CAT-1.
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Affiliation(s)
- Ayelet Grupper
- Nephrology Department, Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv, Israel
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Schwartz IF, Grupper A, Soetendorp H, Hillel O, Laron I, Chernichovski T, Ingbir M, Shtabski A, Weinstein T, Chernin G, Shashar M, Hershkoviz R, Schwartz D. Attenuated glomerular arginine transport prevents hyperfiltration and induces HIF-1α in the pregnant uremic rat. Am J Physiol Renal Physiol 2012; 303:F396-404. [PMID: 22552935 DOI: 10.1152/ajprenal.00488.2011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pregnancy worsens renal function in females with chronic renal failure (CRF) through an unknown mechanism. Reduced nitric oxide (NO) generation induces renal injury. Arginine transport by cationic amino acid transporter-1 (CAT-1), which governs endothelial NO generation, is reduced in both renal failure and pregnancy. We hypothesize that attenuated maternal glomerular arginine transport promotes renal damage in CRF pregnant rats. In uremic rats, pregnancy induced a significant decrease in glomerular arginine transport and cGMP generation (a measure of NO production) compared with CRF or pregnancy alone and these effects were prevented by l-arginine. While CAT-1 abundance was unchanged in all experimental groups, protein kinase C (PKC)-α, phosphorylated PKC-α (CAT-1 inhibitor), and phosphorylated CAT-1 were significantly augmented in CRF, pregnant, and pregnant CRF animals; phenomena that were prevented by coadministrating l-arginine. α-Tocopherol (PKC inhibitor) significantly increased arginine transport in both pregnant and CRF pregnant rats, effects that were attenuated by ex vivo incubation of glomeruli with PMA (a PKC stimulant). Renal histology revealed no differences between all experimental groups. Inulin and p-aminohippurate clearances failed to augment and renal cortical expression of hypoxia inducible factor-1α (HIF-1α) significantly increased in CRF pregnant rat, findings that were prevented by arginine. These studies suggest that in CRF rats, pregnancy induces a profound decrease in glomerular arginine transport, through posttranslational regulation of CAT-1 by PKC-α, resulting in attenuated NO generation. These events provoke renal damage manifested by upregulation of renal HIF-1α and loss of the ability to increase glomerular filtration rate during gestation.
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Affiliation(s)
- Idit F Schwartz
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
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Vina-Vilaseca A, Bender-Sigel J, Sorkina T, Closs EI, Sorkin A. Protein kinase C-dependent ubiquitination and clathrin-mediated endocytosis of the cationic amino acid transporter CAT-1. J Biol Chem 2011; 286:8697-8706. [PMID: 21212261 DOI: 10.1074/jbc.m110.186858] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cationic amino acid transporter 1 (CAT-1) is responsible for the bulk of the uptake of cationic amino acids in most mammalian cells. Activation of protein kinase C (PKC) leads to down-regulation of the cell surface CAT-1. To examine the mechanisms of PKC-induced down-regulation of CAT-1, a functional mutant of CAT-1 (CAT-1-HA-GFP) was generated in which a hemagglutinin antigen (HA) epitope tag was introduced into the second extracellular loop and GFP was attached to the carboxyl terminus. CAT-1-HA-GFP was stably expressed in porcine aorthic endothelial and human epithelial kidney (HEK) 293 cells. Using the HA antibody internalization assay we have demonstrated that PKC-dependent endocytosis was strongly inhibited by siRNA depletion of clathrin heavy chain, indicating that CAT-1-HA-GFP internalization requires clathrin-coated pits. Internalized CAT-1-HA-GFP was accumulated in early, recycling, and late endosomes. PKC activation also resulted in ubiquitination of CAT-1. CAT-1 ubiquitination and endocytosis in phorbol ester-stimulated porcine aorthic endothelial and HEK293 cells were inhibited by siRNA knockdown of NEDD4-2 and NEDD4-1 E3 ubiquitin ligases, respectively. In contrast, ubiquitination and endocytosis of the dopamine transporter was dependent on NEDD4-2 in all cell types tested. Altogether, our data suggest that ubiquitination mediated by NEDD4-2 or NEDD4-1 leading to clathrin-mediated endocytosis is the common mode of regulation of various transporter proteins by PKC.
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Affiliation(s)
- Arnau Vina-Vilaseca
- From the Department of Pharmacology, Anschutz Medical Center, University of Colorado Denver, Aurora, Colorado 80010
| | - Julia Bender-Sigel
- the Department of Pharmacology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz 55101, Germany
| | - Tatiana Sorkina
- the Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, and
| | - Ellen Ildicho Closs
- the Department of Pharmacology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz 55101, Germany
| | - Alexander Sorkin
- From the Department of Pharmacology, Anschutz Medical Center, University of Colorado Denver, Aurora, Colorado 80010,; the Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, and.
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Characterization of the L-arginine-NO-cGMP pathway in spontaneously hypertensive rat platelets: the effects of pregnancy. Hypertens Res 2010; 33:899-904. [PMID: 20555333 DOI: 10.1038/hr.2010.102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Nitric oxide (NO) is a short-lived intercellular messenger that provides an efficient vascular regulatory mechanism to support homeostasis and prevent thrombosis. Endothelial dysfunction and reduced NO bioavailability have a central role in hypertension associated with pregnancy. The purpose of this study was to investigate the impact of pregnancy on the L-arginine-NO-cGMP pathway in platelets and its correlation to platelet function and blood pressure in normotensive rats and spontaneously hypertensive rats (SHRs). Platelets were obtained from blood on the 20th day of pregnancy from female SHRs (SHR-P) and normotensive controls (P) or age-matched nonpregnant rats (SHR-NP and NP). Intraplatelet NO synthase (NOS) activity was reduced in P compared to NP, despite unchanged L-arginine influx. The expression levels of endothelial NOS (eNOS) and inducible NOS (iNOS) were diminished during pregnancy in normotensive rats. Paradoxically, cyclic guanosine monophosphate (cGMP) levels were similar between NP and P, as were phosphodiesterase type 5 (PDE5) expression and platelet aggregation induced by adenosine diphosphate. In SHRs, L-arginine influx was reduced in SHR-P compared to SHR-NP. SHR-P exhibited impaired NOS activity and reduced iNOS expression compared with SHR-NP. Soluble guanylyl cyclase and PDE5 expression in platelets were lower in SHR-P than in SHR-NP, whereas no differences were noted between groups with respect to cGMP levels. However, increased levels of cGMP were observed in SHR-P compared to normotensive groups and platelet aggregability remained unaltered. In conclusion, these observations prompted the hypothesis that normal platelet aggregation in pregnant SHRs may be related to a reduction in PDE5 expression and consequently the maintenance of cGMP levels, independently of reduced platelet NO bioavailability.
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Sankaralingam S, Xu H, Davidge ST. Arginase contributes to endothelial cell oxidative stress in response to plasma from women with preeclampsia. Cardiovasc Res 2010; 85:194-203. [PMID: 19684035 DOI: 10.1093/cvr/cvp277] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
AIMS Preeclampsia is a hypertensive disorder characterized by vascular oxidative stress. Decreased availability of the vasodilator nitric oxide (NO) has been postulated to be involved in the pathophysiology of this disorder. Arginase, an enzyme that competes with nitric oxide synthase (NOS) for l-arginine, not only reduces NO formation but also increases superoxide production by NOS. In placenta of preeclamptic women, arginase upregulation has been shown to be increased and contributes to superoxide formation via uncoupling of NOS. However, the role of arginase in the maternal vasculature is not clear. We hypothesized that arginase would be upregulated in the maternal vasculature of women with preeclampsia and contribute to oxidative stress within the endothelium. METHODS AND RESULTS We observed increased arginase expression in the maternal vasculature of women with preeclampsia compared with normotensive pregnant women. Furthermore, human umbilical vein endothelial cells treated with 2% plasma from preeclamptic women show increased arginase II expression and activity that was reduced by a peroxynitrite scavenger. Also, both 3-morpholino sydnonimine and exogenous peroxynitrite increased arginase expression and activity. Preeclamptic plasma treatment increased superoxide and peroxynitrite levels. Superoxide levels were significantly reduced after arginase and NOS inhibition with [(S)-(2-boronoethyl)-l-cysteine] and N(omega)-nitro-l-arginine methyl ester, respectively, but peroxynitrite levels were in fact increased after arginase inhibition. Moreover, in the presence of preeclamptic plasma, l-arginine supplementation increased peroxynitrite formation during arginase inhibition. CONCLUSION Increased arginase expression in preeclampsia can induce uncoupling of NOS as a source of superoxide in the maternal vasculature in preeclampsia. However, l-arginine supplementation in the face of oxidative stress could lead to a further increase in peroxynitrite.
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Schwartz IF, Chernichovski T, Schwartz D. Aortic arginine transport is attenuated, through post-translational modulation of CAT-1 by PKCalpha, in old male rats. Vasc Med 2009; 15:55-9. [PMID: 19843630 DOI: 10.1177/1358863x09346659] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Experimental models using rats suggest that decreased endothelial nitric oxide synthase (eNOS) activity in old males promotes renal atherosclerosis, whereas females are protected. We aimed to explore whether aging alters aortic arginine uptake by CAT-1, the selective arginine supplier to eNOS in rats. Arginine uptake by freshly harvested aortic rings from young males (9 weeks) was significantly higher than in young females. Old males (18 months) exhibited a significant decrease in arginine transport compared to young males, whereas no differences were observed between old and young females. Cationic amino acid transporter-1 (CAT-1) abundance remained unchanged in all experimental groups. The abundance of protein kinase C alpha (PKCalpha), a CAT-1 inhibitor, was significantly augmented in old versus young males while no differences were detected between old and young females. Phosphorylated PKCalpha was significantly increased in old rats of both sexes. alphaTocopherol, a PKC inhibitor, produced a significant increase in arginine transport in old males only. In conclusion, aortic arginine transport by CAT-1 is attenuated in old male rats through upregulation of PKCalpha. In old females, aortic arginine transport is protected from the effects of PKCalpha by an unknown mechanism.
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Affiliation(s)
- Idit F Schwartz
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine, Tel Aviv, Israel
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Schwartz IF, Chernichovski T, Krishtol N, Grupper A, Laron I, Schwartz D. Sexual dimorphism in glomerular arginine transport affects nitric oxide generation in old male rats. Am J Physiol Renal Physiol 2009; 297:F80-4. [PMID: 19420114 DOI: 10.1152/ajprenal.00020.2009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Animal models suggest that decreased renal endothelial nitric oxide synthase (eNOS) activity in old males promotes renal injury, whereas females are protected. We aimed to explore whether aging alters glomerular arginine uptake by CAT-1, the selective arginine supplier to eNOS in rats. Arginine uptake by glomeruli from young males (3 mo) was significantly higher than in young females. Old males (19 mo) exhibited a significant decrease in arginine transport compared with young males, whereas no differences were observed between old and young females. CAT-1 abundance remained unchanged in all experimental groups. The abundance of PKCalpha (CAT-1 inhibitor) was significantly augmented in young females vs. young males, old vs. young males, and in old females vs. old males. No differences in PKCalpha content were detected between old and young females. Phosphorylated PKCalpha was significantly increased in old rats from both genders. alphaTocopherol, a PKC inhibitor, produced a significant increase in arginine transport and restored NO generation in old males only. Ex vivo incubation of glomeruli from old males with PMA (PKC stimulant) significantly attenuated the effect of tocopherol on arginine uptake. In conclusion, attenuated glomerular arginine transport by CAT-1 contributes to the age-dependent, NO-deficient state in old male rats through upregulation of PKCalpha. In old females glomerular arginine transport is protected from the effects of PKCalpha by an unknown mechanism.
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Affiliation(s)
- Idit F Schwartz
- Department of Nephrology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Sackler School of Medicine,Tel Aviv, Israel.
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Abstract
Preeclampsia, a pregnancy-specific syndrome characterized by hypertension, proteinuria and edema, resolves on delivery of the placenta. Normal pregnancy is itself characterized by systemic inflammation, oxidative stress and alterations in levels of angiogenic factors and vascular reactivity. This is exacerbated in preeclampsia with an associated breakdown of compensatory mechanisms, eventually leading to placental and vascular dysfunction. The underlying pathology of preeclampsia is thought to be a relatively hypoxic or ischemic placenta. Both the placenta and maternal vasculatures are major sources of reactive oxygen and nitrogen species which can interact to produce peroxynitrite a powerful prooxidant that covalently modifies proteins by nitration of tyrosine residues, to possibly alter vascular function in preeclampsia. The linkage between placental hypoxia and maternal vascular dysfunction has been proposed to be via placental syncytiotrophoblast basement membranes shed by the placenta or via angiogenic factors which include soluble flt1 and endoglin secreted by the placenta that bind vascular endothelial growth factor (VEGF) and placental growth factor (PIGF) in the maternal circulation. There is also abundant evidence of altered reactivity of the maternal and placental vasculature and of the altered production of autocoids in preeclampsia. The occurrence of preeclampsia is increased in women with preexisting vascular disease and confers a long-term risk for development of cardiovascular disease. The vascular stress test of pregnancy thus identifies those women with a previously unrecognized at risk vascular system and promotes the development of preeclampsia. Preexisting maternal vascular dysfunction intensified by placental factors is possibly responsible for the individual pathologies of preeclampsia.
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Affiliation(s)
- L Myatt
- Department of Obstetrics & Gynecology, University of Cincinnati, College of Medicine, Cincinnati, OH 45267-0526, USA
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Ingbir M, Schwartz IF, Shtabsky A, Filip I, Reshef R, Chernichovski T, Levin-Iaina N, Rozovski U, Levo Y, Schwartz D. Rosiglitazone improves aortic arginine transport, through inhibition of PKCα, in uremic rats. Am J Physiol Renal Physiol 2008; 295:F471-7. [DOI: 10.1152/ajprenal.00619.2007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Peroxisome proliferator-activated receptor (PPAR) agonists were shown to inhibit atherosclerosis through augmentation of endothelial nitric oxide synthase (eNOS) activity. In addition, rosiglitazone exerts a beneficial effect in chronic renal failure (CRF). Since l-arginine transport by CAT-1 (the specific arginine transporter for eNOS) is inhibited in uremia, we aimed to explore the effect of rosiglitazone on arginine transport in CRF. Arginine uptake by aortic rings was studied in control animals, rats, 6 wk following 5/6 nephrectomy (CRF) and rats with CRF treated with rosiglitazone. The decrease of arginine transport in CRF was prevented by rosiglitazone. Immunobloting revealed that CAT-1 protein was decreased in CRF but remained unchanged following rosiglitazone administration. Protein content of the membrane fraction of PKCα and phosphorylated CAT-1 increased significantly in CRF, effects that were prevented by rosiglitazone. PKCα phosphorylation was unchanged but significantly attenuated by rosiglitazone in CRF. Ex vivo administration of phorbol-12-myristate-13-acetate to rosiglitazone-treated CRF rats significantly attenuated the effect of rosiglitazone on arginine uptake. The decrease in cGMP response to carbamyl-choline (eNOS agonist) was significantly attenuated by rosiglitazone in CRF. Western blotting and immunohistochemistry analysis revealed that protein nitration was intensified in the endothelium of CRF rats and this was attenuated by rosiglitazone. In conclusion, rosiglitazone prevents the decrease in arginine uptake in CRF through both depletion and inactivation of PKCα. These findings are associated with restoration of eNO generation and attenuation of protein nitration and therefore may serve as a novel mechanism to explain the beneficial effects of rosiglitazone on endothelial function in uremia.
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