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Xing Z, Pan L, Yu A, Zhang J, Dong C, Chen J, Xing W, He X, Zhang Z. Value of ultra-high b-value diffusion-weighted imaging for the evaluation of renal ischemia-reperfusion injury. Magn Reson Imaging 2024; 111:1-8. [PMID: 38574980 DOI: 10.1016/j.mri.2024.03.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/26/2024] [Accepted: 03/26/2024] [Indexed: 04/06/2024]
Abstract
To explore the feasibility of ultra-high b-value diffusion-weighted imaging (ubDWI) in assessment of renal IRI. Thirty-five rabbits were randomized into a control group (n = 7) and a renal IRI group (n = 28). The rabbits in the renal IRI group underwent left renal artery clamping for 60 min. Rabbits underwent axial ubDWI before and at 1, 12, 24, and 48 h after IRI. Apparent diffusion coefficient (ADCst) were calculated from ubDWI with two b-values (b = 0, 1000 s/mm2). Triexponential fits were applied to calculate the pure diffusion coefficients (D), perfusion-related diffusion coefficient (D⁎), and ultra-high ADC (ADCuh). The interobserver reproducibility were evaluated. The repeated measurement analysis of variance and Spearman correlation analysis was used for statistical analysis. The ADCst, D, and ADCuh values showed good reproducibility. The ADCst, D, and D⁎ values of renal Cortex (CO) and outer medulla (OM) significantly decreased after IRI (all P < 0.05). The ADCuh values significantly increased from pre-IRI to 1 h after IRI (P < 0.05) and significantly declined at 24 h and 48 h after IRI (all P < 0.05). ADCuh was strongly positively correlated with AQP-1 in the renal CO and OM (ρ = 0.643, P < 0.001; ρ = 0.662, P < 0.001, respectively). ubDWI can be used to non-invasively evaluate early renal IRI, ADCuh may be adopted to reflect AQP-1 expression.
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Affiliation(s)
- Zhaoyu Xing
- Department of Urology, Third Affiliated Hospital of Soochow University, Changzhou 213003, China
| | - Liang Pan
- Department of Radiology, Third Affiliated Hospital of Soochow University, Changzhou, China
| | - Anding Yu
- Department of Radiology, Third Affiliated Hospital of Soochow University, Changzhou, China
| | - Jinggang Zhang
- Department of Radiology, Third Affiliated Hospital of Soochow University, Changzhou, China
| | - Congsong Dong
- Department of Radiology, Affiliated Hospital 6 of Nantong University (Yancheng Third People's Hospital), Yancheng, China
| | - Jie Chen
- Department of Radiology, Third Affiliated Hospital of Soochow University, Changzhou, China
| | - Wei Xing
- Department of Radiology, Third Affiliated Hospital of Soochow University, Changzhou, China
| | - Xiaozhou He
- Department of Urology, Third Affiliated Hospital of Soochow University, Changzhou 213003, China.
| | - Zhiping Zhang
- Department of Radiology, Affiliated Hospital 6 of Nantong University (Yancheng Third People's Hospital), Yancheng, China.
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Barin-Le Guellec C, Largeau B, Bon D, Marquet P, Hauet T. Ischemia/reperfusion-associated tubular cells injury in renal transplantation: Can metabolomics inform about mechanisms and help identify new therapeutic targets? Pharmacol Res 2018; 129:34-43. [PMID: 29309901 DOI: 10.1016/j.phrs.2017.12.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/29/2017] [Accepted: 12/29/2017] [Indexed: 12/31/2022]
Abstract
Tubular cells are central targets of ischemia-reperfusion (I/R) injury in kidney transplantation. Inflammation and metabolic disturbances occurring within these cells are deleterious by themselves but also favor secondary events, such as activation of immune response. It is critical to have an in depth understanding of the mechanisms governing tubular cells response to I/R if one wants to define pertinent biomarkers or to elaborate targeted therapeutic interventions. As oxidative damage was shown to be central in the patho-physiological mechanisms, the impact of I/R on proximal tubular cells metabolism has been widely studied, contrary to its effects on expression and activity of membrane transporters of the proximal tubular cells. Yet, temporal modulation of transporters over ischemia and reperfusion periods appears to play a central role, not only in the induction of cells injury but also in graft function recovery. Metabolomics in cell models or diverse biofluids has the potential to provide large pictures of biochemical consequences of I/R. Metabolomic studies conducted in experimental models of I/R or in transplanted patients indeed retrieved metabolites belonging to the pathways known to be particularly affected. Interestingly, they also revealed that metabolic disturbances and transporters activities are in very close mutual interplay. As well as helping to select diagnostic biomarkers, such analyses could also contribute to identify new pharmacological targets and to set up innovative nephroprotective strategies for the future. Even if various therapeutic approaches have been evaluated for a long time to prevent or treat I/R injuries, metabolomics has helped identifying new ones, those related to membrane transporters seeming to be of particular interest. However, considering the very complex and multifactorial effects of I/R in the context of kidney transplantation, all tracks must be followed if one wants to prevent or limit its deleterious consequences.
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Affiliation(s)
- Chantal Barin-Le Guellec
- INSERM UMR 1248, IPPRITT, Limoges, France; CHU Tours, Laboratory of Biochemistry and Molecular Biology, Tours, France; FHU SUPORT, Limoges, Poitiers, Tours, France.
| | - Bérenger Largeau
- CHU Tours, Laboratory of Biochemistry and Molecular Biology, Tours, France
| | - Delphine Bon
- FHU SUPORT, Limoges, Poitiers, Tours, France; University of Poitiers, Poitiers, France; INSERM UMR 1082, IRTOMIT, Poitiers, France; CHU Poitiers, Laboratory of Biochemistry, Poitiers, France
| | - Pierre Marquet
- INSERM UMR 1248, IPPRITT, Limoges, France; FHU SUPORT, Limoges, Poitiers, Tours, France; University of Limoges, Faculty of Medicine, Limoges, France; CHU Limoges, Department of Pharmacology, Toxicology & Pharmacovigilance, Limoges, France
| | - Thierry Hauet
- FHU SUPORT, Limoges, Poitiers, Tours, France; University of Poitiers, Poitiers, France; INSERM UMR 1082, IRTOMIT, Poitiers, France; CHU Poitiers, Laboratory of Biochemistry, Poitiers, France
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Cha SA, Park BM, Jung YJ, Kim SM, Kang KP, Kim W, Kim SH. Regional heterogeneity of expression of renal NPRs, TonEBP, and AQP-2 mRNAs in rats with acute kidney injury. Peptides 2015; 69:33-9. [PMID: 25858778 DOI: 10.1016/j.peptides.2015.03.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 03/21/2015] [Accepted: 03/30/2015] [Indexed: 12/13/2022]
Abstract
To understand the pathophysiology of ischemia/reperfusion (I/R) - induced acute kidney injury (AKI), the present study defined changes in renal function, plasma renotropic hormones and its receptors in the kidney 2, 5, or 7 days after 45 min-renal ischemia in rats. Blood urea nitrogen, plasma creatinine, and osmolarity increased 2 days after I/R injury and tended to return to control level 7 days after I/R injury. Decreased renal function tended to return to control level 5 days after I/R injury. However, plasma concentrations of atrial natriuretic peptide and renin did not change. In control kidney, natriuretic peptide receptor (NPR)-A, -B and -C mRNAs were highly expressed in medulla (ME), inner cortex (IC), and outer cortex (OC), respectively, and tonicity-responsive enhancer binding protein (TonEBP), auqaporin-2 (AQP-2) and eNOS mRNAs were highly expressed in ME. NPR-A and -B mRNA expressions were markedly decreased 2 days after I/R injury. On 5 days after I/R injury, NPR-A mRNA expression increased in OC and recovered to control level in IC but not in ME. NPR-B mRNA expression was increased in OC, and recovered to control level in IC and ME. NPR-C mRNA expression was markedly decreased in OC 2 and 5 days after I/R injury. TonEBP, APQ-2 and eNOS mRNA expressions were markedly decreased 2 days after I/R injury and did not recover in ME 7 days after I/R injury. Therefore, we suggest that there is a regional heterogeneity of regulation of renal NPRs, TonEBP, and APQ-2 mRNA in AKI.
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Affiliation(s)
- Seung Ah Cha
- Department of Physiology, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Byung Mun Park
- Department of Physiology, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Yu Jin Jung
- Internal Medicine, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Soo Mi Kim
- Department of Physiology, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Kyung Pyo Kang
- Internal Medicine, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Won Kim
- Internal Medicine, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Suhn Hee Kim
- Department of Physiology, Chonbuk National University Medical School, Jeonju, Republic of Korea.
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Abstract
Renal ischaemia/reperfusion (I/R) injury is a common problem that occurs when blood flow is interrupted to the kidney in case of kidney transplantation, aortic cross-clamping and shock with subsequent resuscitation. Renal I/R injury is a complex conditions which includes the onset of an inflammatory process, which is associated with impairment of concentrating ability of the kidney and impairment of solute transport. Characteristically, renal I/R injury is associated with marked reduction in the protein expression of renal aquaporins (AQPs) mainly (AQP1, AQP2 and AQP3), and solute transporters were observed in this condition and could account for the impaired urinary concentration that observed in this condition. Recently, many agents were tested for a possible protective effect against this insult such as erythropoietin (EPO), α-melanocyte-stimulating hormone (α-MSH) and α-lipoic acid which were proved to prevent downregulation of AQPs and solute transporters. The aim of this short review is to outline the potential pathophysiological role of AQPs in renal I/R injury and to put a spotlight on the modulation of renal functions impairment in renal ischaemia by new drugs that prevent downregulation of AQPs.
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Affiliation(s)
- A-A M Hussein
- Department of Physiology, Faculty of Medicine, Mansoura University, Egypt.
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Khan MR, Siddiqui S, Parveen K, Javed S, Diwakar S, Siddiqui WA. Nephroprotective action of tocotrienol-rich fraction (TRF) from palm oil against potassium dichromate (K2Cr2O7)-induced acute renal injury in rats. Chem Biol Interact 2010; 186:228-38. [DOI: 10.1016/j.cbi.2010.04.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 04/19/2010] [Accepted: 04/20/2010] [Indexed: 11/24/2022]
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Kang SW, Kim YW, Kim YH, Sohn HS, Joo H, Kim E. Study of the Association of -667 Aquaporin-2 (AQP-2) A/G Promoter Polymorphism with the Incidence and Clinical Course of Chronic Kidney Disease in Korea. Ren Fail 2009; 29:693-8. [PMID: 17763164 DOI: 10.1080/08860220701460079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
BACKGROUND Impaired urinary concentration is uniformly present with advanced disease in chronic renal failure. Aquaporin-2 (AQP-2) is known to be expressed in the renal collecting duct cells and participates in urinary concentration in response to vasopressin. Recently, the study of AQP expression in various forms of chronic kidney disease (CKD) demonstrated a reduction in AQP-2 expression associated with a loss of nephrons and the presence of chronic interstitial fibrosis. No information on aquaporin genetic variations in CKD is available to date. The aim of our study was to evaluate the possible impact of aquaporin-2 genotype on the development and clinical course of CKD. METHODS Blood samples from 259 patients with CKD and 106 ethnicity-, age-, and sex-matched healthy controls were collected, and genomic DNA was extracted. AQP-2 -667 genotype was assessed by PCR, followed by restriction fragment length polymorphism analysis. RESULTS There were no significant differences in genotype and allele frequencies between the patients and healthy controls (p = 0.3936, p = 0.2941, respectively). In all, 79 (30.5%) patients had the AQP-2 -667 wild-type A/A, 123 (47.5%) were heterozygous for the G allele, and 57 (22.0%) patients showed homozygosity. After subclassification of CKD according to underlying disease, no significant differences were observed between those patients and controls (p = 0.72 for diabetic nephropathy, p = 0.52 for hypertensive nephropathy, p = 0.27 for chronic glomerulonephritis, and p = 0.80 for unknown etiology). Genotype and allele frequencies of the AQP-2 gene polymorphism (rs3759126) of hypertensive patients in pre-ESRD did not show a noticeable difference compared with normal blood pressure patients in pre-ESRD (p = 0.50). No correlation was found to exist between the AQP-2 gene polymorphism (rs3759126) and serum electrolyte levels in pre-ESRD patients (p = 0.38 for serum sodium level and p = 0.44 for serum potassium level). CONCLUSION Our data indicate that no association exists between the -667 AQP-2 A/G polymorphism and susceptibility to CKD or its clinical course.
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Affiliation(s)
- Sun Woo Kang
- Department of Nephrology, Inje University, College of Medicine, Busan, Korea
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Di Giusto G, Anzai N, Endou H, Torres AM. Elimination of organic anions in response to an early stage of renal ischemia-reperfusion in the rat: role of basolateral plasma membrane transporters and cortical renal blood flow. Pharmacology 2007; 81:127-36. [PMID: 17971680 DOI: 10.1159/000110555] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Accepted: 07/12/2007] [Indexed: 01/11/2023]
Abstract
BACKGROUND/AIMS The knowledge of molecular mechanisms determining drug pharmacokinetics in pathological states is relevant for the development of new therapeutic approaches. This study was undertaken to evaluate the cortical renal blood flow (cRBF) and the renal protein expression of the organic anion transporters (OAT1 and OAT3) in association with the elimination of organic anions in an early stage of renal ischemia-reperfusion. METHODS Ischemic acute renal failure (ARF) was induced in adult male Wistar rats by occlusion of both renal pedicles during 60 min, followed by 60 min of reperfusion (ARF group). Pair-fed sham-operated rats served as controls. The renal protein expression of OAT1 and OAT3 was evaluated by immunohistochemistry techniques and by Western blotting in renal cortex homogenates and in basolateral plasma membranes. A pharmacokinetic study of p-aminohippurate (PAH, a prototypical organic anion) was performed. cRBF was determined using fluorescent microspheres. RESULTS ARF rats displayed a significant decrease in systemic clearance and in renal excretion of PAH. OAT1 and OAT3 protein abundance showed a statistically significant reduction both in homogenates and in basolateral plasma membranes from ARF rats. Immunohistochemical studies confirmed the changes in the cortical renal expression of these transporters. ARF animals also showed a decrease in cRBF. CONCLUSIONS The decrease in PAH elimination observed in an early stage of renal ischemia-reperfusion in male Wistar rats might be explained by the sum of the lower OAT1 and OAT3 expression in renal basolateral plasma membranes plus the decrease in cRBF. These findings might have significant implications in the development of novel pharmacological strategies to be applied in the initial stages of ischemic ARF.
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Affiliation(s)
- Gisela Di Giusto
- Farmacología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, CONICET, Rosario, Argentina
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Han KH, Kim HY, Croker BP, Reungjui S, Lee SY, Kim J, Handlogten ME, Adin CA, Weiner ID. Effects of ischemia-reperfusion injury on renal ammonia metabolism and the collecting duct. Am J Physiol Renal Physiol 2007; 293:F1342-54. [PMID: 17686949 DOI: 10.1152/ajprenal.00437.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute renal injury induces metabolic acidosis, but its specific effects on the collecting duct, the primary site for urinary ammonia secretion, the primary component of net acid excretion, are incompletely understood. We induced ischemia-reperfusion (I/R) acute renal injury in Sprague-Dawley rats by clamping the renal pedicles bilaterally for 30 min followed by reperfusion for 6 h. Control rats underwent sham surgery without renal pedicle clamping. I/R injury decreased urinary ammonia excretion significantly but did not persistently alter urine volume, Na+, K+, or bicarbonate excretion. Histological examination demonstrated cellular damage in the outer and inner medullary collecting duct, as well as in the proximal tubule and the thick ascending limb of the loop of Henle. A subset of collecting duct cells were damaged and/or detached from the basement membrane; these cells were present predominantly in the outer medulla and were less frequent in the inner medulla. Immunohistochemistry identified that the damaged/detached cells were A-type intercalated cells, not principal cells. Both TdT-mediated dUTP nick-end labeling (TUNEL) staining and transmission electron microscopic examination demonstrated apoptosis but not necrosis. However, immunoreactivity for caspase-3 was observed in the proximal tubule, but not in collecting duct intercalated cells, suggesting that mechanism(s) of collecting duct intercalated cell apoptosis differ from those operative in the proximal tubule. We conclude that I/R injury decreases renal ammonia excretion and is associated with intercalated cell-specific detachment and apoptosis in the outer and inner medullary collecting duct. These effects likely contribute to the metabolic acidosis frequently observed in acute renal injury.
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Affiliation(s)
- Ki-Hwan Han
- Department of Anatomy, Ewha Womans University, Seoul, Korea
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Wang Y, Chen WM, Gao LL, Liu JG. Dopamine modulates perioperative renal medulla aquaporin 2 expression in experimental obstructive jaundice. Shijie Huaren Xiaohua Zazhi 2007; 15:2714-2717. [DOI: 10.11569/wcjd.v15.i25.2714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the changes in aquaporin 2 expression after bile duct recanalization and the effects of low-dose dopamine on perioperative renal aquaporin 2 expression.
METHODS: Seventy wistar rats were randomly allocated to 4 groups. Sixty rats underwent common bile duct ligation, while the other 10 underwent sham operation. The common duct was ligated on a silicon tube of 2 mm external diameter. Seven days later, the experimental rats were randomly allocated into another 3 groups. Rats in the obstructive jaundice group were injected with 9 g/L normal saline (NS), while those in the other 2 groups were injected with dopamine at 5 or 10 µg/(kg•min), respectively. After 2 h treatment, half in each group were killed and the others were killed 24 h later. Serum was collected from each rat to assess hepatic and renal functions. The right renal medulla was separated and kept at -80℃ until used to measure aquaporin 2 expressions by Western blotting.
RESULTS: In the early period of bile duct recanalization, serum bilirubin levels decreased. There were no significant changes in blood urine or creatine. Renal aquaporin 2 expression was detected by Western blotting. Aquaporin 2 expression in the experimental group treated with dopamine 5 µg/(kg•min) was nearly the same as that in the normal group, both at 0 and 24 h (16 010 ± 646 and 22 715 ± 575 vs 21 966 ± 1544 and 21 917 ± 2661), and better than the group treated with dopamine 10 µg/(kg•min).
CONCLUSION: Low-dose dopamine injection appears to modulate expression of aquaporin 2 in the renal collective tubule epithelium, and to have a positive effect on perioperative renal function in obstructive jaundice.
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Iacobas DA, Fan C, Iacobas S, Spray DC, Haddad GG. Transcriptomic changes in developing kidney exposed to chronic hypoxia. Biochem Biophys Res Commun 2006; 349:329-38. [PMID: 16934745 DOI: 10.1016/j.bbrc.2006.08.056] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 08/10/2006] [Accepted: 08/10/2006] [Indexed: 01/12/2023]
Abstract
cDNA arrays compared gene expression in kidneys of neonatal mice subjected to 1, 2, and 4 weeks of chronic constant (CCH) or intermittent (CIH) hypoxia with normoxic littermates. Five to twenty percent of genes were regulated in each condition, with greater changes in CCH. Up-regulation of 42% of the solute carriers after 1 week of CCH suggests a strong activation of pH controlling pathways. Significant reduction in expression change of genes important in growth, development, and aging as a function of time indicates reduced maturation rate in CIH and CCH treatments. Regulated genes showed gender dependence in CCH, being higher in females than males at 1 week and higher in males than females thereafter. Transcriptional control was enhanced in CCH but not in CIH. Thus, CCH and CIH both alter gene expression and retard maturation with the more profound changes occurring in CCH than in CIH.
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Affiliation(s)
- Dumitru A Iacobas
- Department of Neuroscience, Kennedy Center, Room #915C, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, New York, NY 10461, USA.
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Jiang W, Prokopenko O, Wong L, Inouye M, Mirochnitchenko O. IRIP, a new ischemia/reperfusion-inducible protein that participates in the regulation of transporter activity. Mol Cell Biol 2005; 25:6496-508. [PMID: 16024787 PMCID: PMC1190334 DOI: 10.1128/mcb.25.15.6496-6508.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the identification and characterization of a new ischemia/reperfusion-inducible protein (IRIP), which belongs to the SUA5/YrdC/YciO protein family. IRIP cDNA was isolated in a differential display analysis of an ischemia/reperfusion-treated kidney RNA sample. Mouse IRIP mRNA was expressed in all tissues tested, the highest level being in the testis, secretory, and endocrine organs. Besides ischemia/reperfusion, endotoxemia also activated the expression of IRIP in the liver, lung, and spleen. The transporter regulator RS1 was identified as an IRIP-interacting protein in yeast two-hybrid screening. The interaction between IRIP and RS1 was further confirmed in coimmunoprecipitation assays. A possible role of IRIP in regulating transporter activity was subsequently investigated. IRIP overexpression inhibited endogenous 1-methyl-4-phenylpyridinium (MPP+) uptake activity in HeLa cells. The activities of exogenous organic cation transporters (OCT2 and OCT3), organic anion transporter (OAT1), and monoamine transporters were also inhibited by IRIP. Conversely, inhibition of IRIP expression by small interfering RNA or antisense RNA increased MPP+ uptake. We measured transport kinetics of OCT2-mediated uptake and demonstrated that IRIP overexpression significantly decreased V(max) but did not affect K(m). On the basis of these results, we propose that IRIP regulates the activity of a variety of transporters under normal and pathological conditions.
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Affiliation(s)
- Wei Jiang
- Department of Biochemistry, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA
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Abstract
The expression of aquaporin-2 (AQP2) is decreased in rats with bilateral ureteral obstruction (BUO) and unilateral ureteral obstruction (UUO). Therefore, the expression of additional renal aquaporins (AQP1-4) and phosphorylated AQP2 (p-AQP2), known to play a role in urinary concentration, was examined in a Wistar rat model with 24 h of UUO. In obstructed kidneys, immunoblotting revealed a significant decrease in the expression of inner medullary AQP2 to 42 +/- 4, p-AQP2 to 23 +/- 5, AQP3 to 19 +/- 6, AQP4 to 11 +/- 5, and AQP1 to 64 +/- 8% of sham levels. AQP1 expression located in the proximal tubule decreased to 74 +/- 4% of sham levels (P < 0.05). Immunocytochemistry confirmed the downregulation of AQP3, AQP4, and p-AQP2. In contralateral nonobstructed kidneys, immunoblotting also revealed significant reductions of AQP1 in the inner medulla, outer medulla, and cortex, whereas expression of AQP2, AQP3, AQP4, and p-AQP2 was unchanged. Furthermore, we collected the urine from both obstructed and nonobstructed kidneys for 2 h, respectively, after 24 h of UUO. Urine collection from obstructed kidneys during 2 h after release of UUO revealed a significant reduction in urine osmolality and solute-free water reabsorption (T(c)H(2)O). Moreover, an increase in urine production and T(c)H(2)O was observed in contralateral kidneys. To examine whether vasopressin-independent mechanisms are involved in AQP2 regulation, vasopressin-deficient Brattleboro (BB) rats with 24 h of UUO were examined. Immunoblotting revealed downregulation of AQP2, p-AQP2, AQP3, and AQP1 in obstructed kidneys and downregulation of p-AQP2 and AQP1 in nonobstructed kidneys. In conclusion, 1) UUO is associated with severe downregulation of AQP2, AQP3, AQP4, and AQP1; thus all of these AQPs may play important roles in the impaired urinary concentrating capacity in the obstructed kidney; 2) the reduced levels of AQP1 in the nonobstructed kidney may contribute to the compensatory increase in urine production; and 3) downregulation of AQPs in BB rats supports the view that vasopressin-independent pathways may be involved in AQP2 and AQP3 regulation in the obstructed kidney.
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Affiliation(s)
- Chunling Li
- The Water and Salt Research Center, University of Aarhus, DK-8000 Aarhus C, Denmark
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Nakamura T, Saito T, Kusaka I, Higashiyama M, Nagasaka S, Ishibashi S, Ishikawa SE. Decrease in urinary excretion of aquaporin-2 associated with impaired urinary concentrating ability in diabetic nephropathy. Nephron Clin Pract 2002; 92:445-8. [PMID: 12218327 DOI: 10.1159/000063285] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Aquaporin-2 (AQP-2) is known to be expressed in the renal collecting duct cells and participates in urinary concentration in response to arginine vasopressin (AVP). The present study was undertaken to determine whether progression of renal dysfunction affects urinary excretion of AQP-2 in diabetic nephropathy. The study was composed of 8 control subjects and 14 patients with type 2 diabetes classified into two groups according to serum creatinine level (cut-off point; 1.5 mg/dl). After an 8-hour water deprivation, both urinary osmolality (U(osm)) and urinary excretion of AQP-2 significantly decreased in the diabetic patients with chronic renal failure as compared to the control subjects (p < 0.0001, p < 0.05, respectively). After a water load (10 ml/kg), no differences were found in plasma osmolality (P(osm)), AVP levels and U(osm), whereas urinary excretion of AQP-2 significantly decreased in the patients with chronic renal failure as compared to the control subjects (p < 0.05). These results indicate that the decreased urinary excretion of AQP-2 in diabetic nephropathy is due to the impaired cellular signaling of AVP in collecting duct cells, which may be partly involved in the urinary concentrating defect in renal failure.
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Affiliation(s)
- Tomoatsu Nakamura
- Department of Medicine, Division of Endocrinology and Metabolism, Jichi Medical School, Tochigi, Japan
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