Endothelial-specific overexpression of cationic amino acid transporter-1 prevents loss of kidney function in heart failure

Abstract Heart failure (HF) is associated with impaired L-arginine transport. In the present study, we tested the hypothesis that augmented L-arginine transport prevents the loss of kidney function in HF. Renal function was assessed in wildtype mice (WT), transgenic mice with HF (dilated cardiomyopathy, DCM) and double transgenic mice (double transgenic mice with DCM and CAT-1 overexpression, HFCAT-1) with HF and endothelial-specific overexpression of the predominant L-arginine transporter, cationic amino acid transporter-1 (CAT-1) (n=4-8/group). Cardiac function was assessed via echocardiography and left ventricular catheterisation. Renal function was assessed via quantification of albuminuria and creatinine clearance. Plasma nitrate and nitrite levels together with renal fibrosis and inflammatory markers were also quantified at study end. Albumin/creatinine ratio was two-fold greater in DCM mice than in WT mice (P=0.002), and tubulointerstitial and glomerular fibrosis were approximately eight- and three-fold greater, respectively, in DCM mice than in WT mice (P≤0.02). Critically, urinary albumin/creatinine ratio and tubulointerstitial and glomerular fibrosis were less in HFCAT-1 mice than in DCM mice (P<0.05). Renal CAT-1 expression and plasma nitrate and nitrite levels were less in DCM mice compared with WT (P≤0.03) but was greater in HFCAT-1 mice than in DCM mice (P≤0.009). Renal expression of IL-10 was less in DCM mice compared with WT (P<0.001) but was greater in HFCAT-1 mice compared with DCM mice (P=0.02). Our data provide direct evidence that augmented L-arginine transport prevents renal fibrosis, inflammation and loss of kidney function in HF.

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l-Arginine and Cationic Amino Acid Transporter 2B Regulate Growth and Survival of Leishmania amazonensis Amastigotes in Macrophages

Infection and Immunity ◽

10.1128/iai.00026-07 ◽

2007 ◽

Vol 75 (6) ◽

pp. 2802-2810 ◽

Cited By ~ 44

Author(s):

Nanchaya Wanasen ◽

Carol L. MacLeod ◽

Lesley G. Ellies ◽

Lynn Soong

Keyword(s):

Amino Acid ◽

Amino Acid Transporter ◽

Parasite Growth ◽

Leishmania Amazonensis ◽

Growth Enhancement ◽

Cationic Amino Acid Transporter ◽

Cationic Amino Acid ◽

Arginine Transport ◽

Ifn Γ ◽

Acid Transporter

ABSTRACT Leishmania spp. are obligate intracellular parasites, requiring a suitable microenvironment for their growth within host cells. We previously reported that the growth of Leishmania amazonensis amastigotes in murine macrophages (Mφs) was enhanced in the presence of gamma interferon (IFN-γ), a Th1 cytokine normally associated with classical Mφ activation and killing of intracellular pathogens. In this study, we provided several lines of evidence suggesting that IFN-γ-mediated parasite growth enhancement was associated with l-arginine transport via mouse cationic amino acid transporter 2B (mCAT-2B). (i) mRNA expression of Slc7A2, the gene encoding for mCAT-2B, as well as l-arginine transport was increased in IFN-γ-treated Mφs. (ii) Supplementation of l-arginine in Mφ cultures increased parasite growth. (iii) Parasite growth enhancement in wild-type Mφs was inhibited in the presence of nonmetabolized l-arginine analogues. (iv) IFN-γ-mediated parasite growth was absent in Mφs derived from mCAT-2B-deficient mice. Although we detected a clear upregulation of mCAT-2B and l-arginine transport, no measurable iNOS or arginase activities were observed in IFN-γ-treated, infected Mφs. Together, these data suggest an involvement of a novel l-arginine usage independent of iNOS and arginase activities during IFN-γ-mediated parasite growth enhancement. A possible role of mCAT-2B in supplying l-arginine directly to the parasites for their proliferation is discussed.

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Estradiol augments while progesterone inhibits arginine transport in human endothelial cells through modulation of cationic amino acid transporter-1

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00532.2014 ◽

2015 ◽

Vol 309 (4) ◽

pp. R421-R427 ◽

Cited By ~ 13

Author(s):

Ohad S. Bentur ◽

Doron Schwartz ◽

Tamara Chernichovski ◽

Merav Ingbir ◽

Talia Weinstein ◽

...

Keyword(s):

Endothelial Cells ◽

Amino Acid ◽

Protein Content ◽

Amino Acid Transporter ◽

Female Rats ◽

Cationic Amino Acid Transporter ◽

Cationic Amino Acid ◽

Arginine Transport ◽

Arginine Uptake ◽

Acid Transporter

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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Association of l-arginine transporters with fodrin: implications for hypoxic inhibition of arginine uptake

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.2000.278.1.l111 ◽

2000 ◽

Vol 278 (1) ◽

pp. L111-L117 ◽

Cited By ~ 38

Author(s):

S. I. Zharikov ◽

E. R. Block

Keyword(s):

Plasma Membranes ◽

Calpain Inhibitor ◽

Cationic Amino Acid Transporter ◽

Transport Activity ◽

Cationic Amino Acid ◽

Arginine Transport ◽

Arginine Uptake ◽

Hydrolysis Of ◽

Expression And Activity

In this study, we investigated the possible interaction between the cationic amino acid transporter (CAT)-1 arginine transporter and ankyrin or fodrin. Because ankyrin and fodrin are substrates for calpain and because hypoxia increases calpain expression and activity in pulmonary artery endothelial cells (PAEC), we also studied the effect of hypoxia on ankyrin, fodrin, and CAT-1 contents in PAEC. Exposure to long-term hypoxia (24 h) inhibited l-arginine uptake by PAEC, and this inhibition was prevented by calpain inhibitor 1. The effects of hypoxia and calpain inhibitor 1 were not associated with changes in CAT-1 transporter content in PAEC plasma membranes. However, hypoxia stimulated the hydrolysis of ankyrin and fodrin in PAEC, and this could be prevented by calpain inhibitor 1. Incubation of solubilized plasma membrane proteins with anti-fodrin antibodies resulted in a 70% depletion of CAT-1 immunoreactivity and in a 60% decrease in l-arginine transport activity in reconstituted proteoliposomes (3,291 ± 117 vs. 8,101 ± 481 pmol ⋅ mg protein−1 ⋅ 3 min−1 in control). Incubation with anti-ankyrin antibodies had no effect on CAT-1 content or l-arginine transport in reconstituted proteoliposomes. These results demonstrate that CAT-1 arginine transporters in PAEC are associated with fodrin, but not with ankyrin, and that long-term hypoxia decreases l-arginine transport by a calpain-mediated mechanism that may involve fodrin proteolysis.

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Binding specificity of the l-arginine transport systems in mouse macrophages and human cells overexpressing the cationic amino acid transporter hCAT-1

Amino Acids ◽

10.1007/s00726-008-0106-x ◽

2008 ◽

Vol 36 (3) ◽

pp. 483-492 ◽

Cited By ~ 4

Author(s):

Dániel Erős ◽

László Őrfi ◽

Ildikó Csuka ◽

György Kéri ◽

András Hrabák

Keyword(s):

Amino Acid ◽

Binding Specificity ◽

Amino Acid Transporter ◽

Human Cells ◽

Transport Systems ◽

Cationic Amino Acid Transporter ◽

Cationic Amino Acid ◽

Arginine Transport ◽

Mouse Macrophages ◽

Acid Transporter

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Abstract 234: Reduction of LpX and Improvement in Kidney Function in LCAT-KO Mice by Enzyme Replacement Therapy

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.36.suppl_1.234 ◽

2016 ◽

Vol 36 (suppl_1) ◽

Author(s):

Boris L Vaisman ◽

Edward B Neufeld ◽

Lita A Freeman ◽

Maureen L Sampson ◽

Milton Pryor ◽

...

Keyword(s):

Mouse Model ◽

Renal Disease ◽

Kidney Function ◽

Chow Diet ◽

Creatinine Ratio ◽

Kidney Dysfunction ◽

Albumin Creatinine Ratio ◽

Normal Chow ◽

Lcat Deficiency ◽

Normal Chow Diet

Familial LCAT Deficiency (FLD) is associated with the gradual development of severe kidney dysfunction from the renal deposition of LpX, an abnormal lipoprotein that accumulates in this disorder. The aim of our study was to develop an efficient mouse model of FLD in which elevated plasma LpX and kidney dysfunction can be rapidly induced in order to test whether recombinant human LCAT (rhLCAT) injections can prevent renal disease. We used the previously described LCAT-Ko x SREBP1a transgenic mouse model (Zhu et al., 2004) with the transgene placed under control of PEPCK promoter, which can be induced by high protein diets. We demonstrate that high levels of LpX plasma particles appeared within 5-7 days after 2-3 month old mice were switched to a protein rich carbohydrate low diet (PRCL). Kidney dysfunction measured by albumin/creatinine ratio after 9 days on PRCL diet increased by 32±12 fold. On the PRCL diet, plasma VLDL-C and LDL-C fractions of LCAT-Ko x SREBP1a mice increased 2-4 fold compared to mice on a normal chow diet. Transmission electron microscopy clearly demonstrated the presence of multilamellar LpX particles in plasma and renal glomeruli, as well as robust accumulation lipid droplets in hepatocytes of mice kept on the PRCL diet for 7 days. All these changes were reversible; when mice were returned to the normal chow diet their plasma lipid characteristics and kidney function quickly returned within days to the level observed before the diet was initiated. When LCAT-Ko x SREBP1a mice were placed on PRCL diet and simultaneously treated with rhLCAT (x 3 per week IV injection 30 mg/kg for 2 weeks) plasma LpX was eliminated and a normal mouse lipoprotein profile was observed and most notably HDL-C increased from 5.6 g/dL to 54.1 mg/dL. Treatment with rhLCAT decreased the albumin/creatinine ratio 5±1 fold. Conclusions: LCAT-Ko and SREBP1a mice on a PRCL diet can be used as efficient model for investigating potential therapies for LCAT deficiency. Results show the feasibility of rhLCAT treatment for preventing renal disease in patients with FLD.

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Evaluation of methods for rapid microalbuminuria screening in kidney diseased patients

Srpski arhiv za celokupno lekarstvo ◽

10.2298/sarh1204173d ◽

2012 ◽

Vol 140 (3-4) ◽

pp. 173-178

Author(s):

Marijana Dajak ◽

Ana Bontic ◽

Svetlana Ignjatovic ◽

Jelena Pavlovic ◽

Nada Majkic-Singh ◽

...

Keyword(s):

Positive Predictive Value ◽

Kidney Function ◽

Predictive Value ◽

Kidney Diseases ◽

Test Strip ◽

Urine Specimen ◽

Albumin Concentration ◽

Creatinine Ratio ◽

Albumin Creatinine Ratio ◽

Spot Urine

Introduction. One of the criteria for chronic kidney disease detection is determination of microalbuminuria. Objective. This analysis was performed to evaluate accuracy of three useful methods for microalbuminuria detection in 24h urine collection and in the morning urine specimen calculated from urine albumin creatinine ratio, or with a dipstick in patients with different kidney diseases or kidney function. Methods. Microalbuminuria was detected in 74 patients referred to the Outpatient Nephrology Department for kidney function determination or regular nephrology checking. Albumin concentration determined using immunonephelometry was lower than 300 mg/day. Discriminates cutoff values for spot urine test strip and albumin creatinin ratio in predicting 24 h protein ?threshold? excretion were determined using ROC analysis. Results. Mean value of 24 h microalbuminuria was 80.3 mg/24 h, and value >30 mg/24 h was present in 71.8% of patient. Correlation coefficients between dipstick microalbuminuria or albumin/creatinine ratio in a spot urine specimen and 24 h microalbuminuria were 0.709 and 0.598 (p<0.0001). For pathological value of 24 h microalbuminuria >30 mg/24 h, the coresponding dipstick microalbuminuria value was ?20 mg/L (AUC 0.849, specificity 95%, positive predictive value 97.3%), and ?3.55 mg albumin/mmol creatinine ratio (AUC 0.914, specificity 90% and positive predictive value 95.5%). No difference was found between dipstick mikroalbuminuria and albumin/creatinine ratio value. In addition, albumin/creatinine ratio value from 24 h urine was similar to the value obtained from the spot urine sample. Conclusion. Obtained results indicated that albuminuria could be determined accurately in spot urine either with the Micral test strip or with albumin creatinine ratio.

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The Effect of Diabetes and the Diabetogenic TBC1D4 p.Arg684Ter Variant on Kidney Function in Inuit in Greenland

10.21203/rs.3.rs-1214858/v1 ◽

2022 ◽

Author(s):

Maria Overvad ◽

Lars Jorge Diaz ◽

Peter Bjerregaard ◽

Michael Lynge Pedersen ◽

Christina Viskum Lytken Larsen ◽

...

Keyword(s):

Kidney Function ◽

Population Based ◽

Longitudinal Analyses ◽

Creatinine Ratio ◽

Multivariable Model ◽

Albumin Creatinine Ratio ◽

Increased Risk ◽

Health Survey Data ◽

Design And Methods

Abstract ObjectiveDiabetes prevalence in Greenland is high and increasing. The aim of this study was to examine the effect of diabetes and the diabetogenic TBC1D4 variant on kidney function in Greenland in a population-based setting.Research Design and MethodsHealth survey data and TBC1D4 genotypes from 5,336 Greenlanders was used to estimate odds ratios (ORs) of albuminuria (>30 mg/g creatinine) and chronic kidney disease (CKD, eGFR<60 ml/min/1.73m2), comparing individuals with and without diabetes. Using baseline and follow-up data from individuals who participated in two surveys we examined the effect of diabetes on eGFR and urinary albumin creatinine ratio (UACR) at follow-up, stepwise adjusting for baseline confounders including the TBC1D4 variant.ResultsA total of 9.3% had diabetes of the 3,909 participants with complete data. Albuminuria and CKD was found in 27.6% and 9.5% among those with and without diabetes respectively. Diabetes was associated with increased risk of albuminuria (OR(95% CI) = 2.37 (1.69,3.33) p<0.001) and the TBC1D4 variant protected against albuminuria (OR(95% CI) = 0.44 (0.22,0.90) p=0.02) in a multivariable model. Neither diabetes nor the TBC1D4 variant significantly associated with CKD. Diabetes was not associated with changes in eGFR or UACR over a median of 11.3 years.ConclusionDiabetes conferred increased risk of albuminuria and the TBC1D4 variant was associated with decreased risk of albuminuria, but neither were associated with CKD. The presence/absence of diabetes did not predict changes in eGFR and UACR in longitudinal analyses. The potential renoprotective association of the TBC1D4 variant on albuminuria calls for further studies.

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