1
|
Xu Y, Zhang H, Li N, Ma W, Wang S, Sun J, Yang B. Preclinical Pharmacokinetic Studies of a Novel Diuretic Inhibiting Urea Transporters. Molecules 2022; 27:2451. [PMID: 35458649 PMCID: PMC9027532 DOI: 10.3390/molecules27082451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 04/02/2022] [Accepted: 04/07/2022] [Indexed: 11/16/2022] Open
Abstract
Urea transporter (UT) inhibitors are a class of promising novel diuretics that do not cause the imbalance of Na+, K+, Cl-, and other electrolytes. In our previous studies, 25a, a promising diuretic candidate inhibiting UT, was discovered and showed potent diuretic activities in rodents. Here, a sensitive liquid chromatography-tandem mass spectrometry method for the quantitation of 25a in rat plasma, urine, feces, bile, and tissue homogenates was developed and validated to support the preclinical pharmacokinetic studies. The tissue distribution, excretion, and plasma protein binding were investigated in rats. After a single oral dose of 25a at 25, 50, and 100 mg/kg, the drug exposure increased linearly with the dose. The drug accumulation was observed after multiple oral doses compared to a single dose. In the distribution study, 25a exhibited a wide distribution to tissues with high blood perfusion, such as kidney, heart, lung, and spleen, and the lowest distribution in the brain and testis. The accumulative excretion rate of 25a was 0.14%, 3.16%, and 0.018% in urine, feces, and bile, respectively. The plasma protein binding of 25a was approximately 60% in rats and 40% in humans. This is the first study on the preclinical pharmacokinetic profiles of 25a.
Collapse
Affiliation(s)
- Yue Xu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.X.); (H.Z.); (N.L.); (S.W.)
| | - Hang Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.X.); (H.Z.); (N.L.); (S.W.)
| | - Nannan Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.X.); (H.Z.); (N.L.); (S.W.)
| | - Wen Ma
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China;
| | - Shuyuan Wang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.X.); (H.Z.); (N.L.); (S.W.)
| | - Jianguo Sun
- Key Lab of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, 24 Tongjiaxiang Street, Nanjing 210009, China;
| | - Baoxue Yang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.X.); (H.Z.); (N.L.); (S.W.)
| |
Collapse
|
2
|
Zhang S, Zhao Y, Wang S, Li M, Xu Y, Ran J, Geng X, He J, Meng J, Shao G, Zhou H, Ge Z, Chen G, Li R, Yang B. Discovery of novel diarylamides as orally active diuretics targeting urea transporters. Acta Pharm Sin B 2021; 11:181-202. [PMID: 33532188 PMCID: PMC7838058 DOI: 10.1016/j.apsb.2020.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/14/2020] [Accepted: 05/26/2020] [Indexed: 12/17/2022] Open
Abstract
Urea transporters (UT) play a vital role in the mechanism of urine concentration and are recognized as novel targets for the development of salt-sparing diuretics. Thus, UT inhibitors are promising for development as novel diuretics. In the present study, a novel UT inhibitor with a diarylamide scaffold was discovered by high-throughput screening. Optimization of the inhibitor led to the identification of a promising preclinical candidate, N-[4-(acetylamino)phenyl]-5-nitrofuran-2-carboxamide (1H), with excellent in vitro UT inhibitory activity at the submicromolar level. The half maximal inhibitory concentrations of 1H against UT-B in mouse, rat, and human erythrocyte were 1.60, 0.64, and 0.13 μmol/L, respectively. Further investigation suggested that 8 μmol/L 1H more powerfully inhibited UT-A1 at a rate of 86.8% than UT-B at a rate of 73.9% in MDCK cell models. Most interestingly, we found for the first time that oral administration of 1H at a dose of 100 mg/kg showed superior diuretic effect in vivo without causing electrolyte imbalance in rats. Additionally, 1H did not exhibit apparent toxicity in vivo and in vitro, and possessed favorable pharmacokinetic characteristics. 1H shows promise as a novel diuretic to treat hyponatremia accompanied with volume expansion and may cause few side effects.
Collapse
Key Words
- AQP1, aquaporin 1
- BCRP, breast cancer resistance protein
- CCK-8, cell counting kit-8
- CMC-Na, carboxymethylcellulose sodium
- DMF, N,N-dimethylformamide
- Diuretic
- Fa, fraction absorbance
- GFR, glomerular filtration rate
- HDL-C and LDL-C, high- and low-density lipoprotein
- IC50, half maximal inhibitory concentration
- IMCD, inner medulla collecting duct
- Oral administration
- P-gp, P-glycoprotein
- PBS, phosphate buffered saline
- Papp, apparent permeability
- Structure optimization
- THF, tetrahydrofuran
- UT, urea transporter
- Urea transporter inhibitor
- r.t., room temperature
Collapse
|
3
|
Kabutomori J, Pina-Lopes N, Musa-Aziz R. Water transport mediated by murine urea transporters: implications for urine concentration mechanisms. Biol Open 2020; 9:bio051805. [PMID: 32661130 PMCID: PMC7438002 DOI: 10.1242/bio.051805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 06/30/2020] [Indexed: 12/01/2022] Open
Abstract
Urea transporters (UTs) facilitate urea diffusion across cell membranes and play an important role in the urinary concentration mechanisms in the kidney. Herein, we injected cRNAs encoding for c-Myc-tagged murine UT-B, UT-A2 or UT-A3 (versus water-injected control) in Lithobates oocytes and evaluated oocyte surface protein expression with biotinylation and immunoblotting, urea uptake using [14C] counts and water permeability (P f ) by video microscopy. Immunoblots of UT-injected oocyte membranes revealed bands with a molecular weight consistent with that of a UT monomer (34 kDa), and UT-injected oocytes displayed significantly increased and phloretin-sensitive urea uptake and P f when compared to day-matched control oocytes. Subtracting the water-injected urea uptake or P f values from those of UT-injected oocytes yielded UT-dependent values*. We demonstrate for the first time that UT-A2 and UT-A3 can transport water, and we confirm that UT-B is permeable to water. Moreover, the [14C] urea*/P f * ratios fell in the sequence mUT-B>mUT-A2>mUT-A3, indicating that UTs can exhibit selectivity to urea and/or water. It is likely that specific kidney regions with high levels of UTs will exhibit increased urea and/or water permeabilities, directly influencing urine concentration. Furthermore, UT-mediated water transport activity must be considered when developing UT-inhibitors as novel diuretics.This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- J Kabutomori
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil 05508-900
| | - N Pina-Lopes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil 05508-900
| | - R Musa-Aziz
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil 05508-900
| |
Collapse
|
4
|
Geng X, Zhang S, He J, Ma A, Li Y, Li M, Zhou H, Chen G, Yang B. The urea transporter UT-A1 plays a predominant role in a urea-dependent urine-concentrating mechanism. J Biol Chem 2020; 295:9893-9900. [PMID: 32461256 PMCID: PMC7380188 DOI: 10.1074/jbc.ra120.013628] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/22/2020] [Indexed: 12/12/2022] Open
Abstract
Urea transporters are a family of urea-selective channel proteins expressed in multiple tissues that play an important role in the urine-concentrating mechanism of the mammalian kidney. Previous studies have shown that knockout of urea transporter (UT)-B, UT-A1/A3, or all UTs leads to urea-selective diuresis, indicating that urea transporters have important roles in urine concentration. Here, we sought to determine the role of UT-A1 in the urine-concentrating mechanism in a newly developed UT-A1-knockout mouse model. Phenotypically, daily urine output in UT-A1-knockout mice was nearly 3-fold that of WT mice and 82% of all-UT-knockout mice, and the UT-A1-knockout mice had significantly lower urine osmolality than WT mice. After 24-h water restriction, acute urea loading, or high-protein (40%) intake, UT-A1-knockout mice were unable to increase urine-concentrating ability. Compared with all-UT-knockout mice, the UT-A1-knockout mice exhibited similarly elevated daily urine output and decreased urine osmolality, indicating impaired urea-selective urine concentration. Our experimental findings reveal that UT-A1 has a predominant role in urea-dependent urine-concentrating mechanisms, suggesting that UT-A1 represents a promising diuretic target.
Collapse
Affiliation(s)
- Xiaoqiang Geng
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Shun Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Jinzhao He
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Ang Ma
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Yingjie Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Min Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Hong Zhou
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Guangping Chen
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Baoxue Yang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
- Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, China
| |
Collapse
|
5
|
Kuma A, Wang XH, Klein JD, Tan L, Naqvi N, Rianto F, Huang Y, Yu M, Sands JM. Inhibition of urea transporter ameliorates uremic cardiomyopathy in chronic kidney disease. FASEB J 2020; 34:8296-8309. [PMID: 32367640 PMCID: PMC7302978 DOI: 10.1096/fj.202000214rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/09/2020] [Accepted: 04/09/2020] [Indexed: 02/07/2023]
Abstract
Uremic cardiomyopathy, characterized by hypertension, cardiac hypertrophy, and fibrosis, is a complication of chronic kidney disease (CKD). Urea transporter (UT) inhibition increases the excretion of water and urea, but the effect on uremic cardiomyopathy has not been studied. We tested UT inhibition by dimethylthiourea (DMTU) in 5/6 nephrectomy mice. This treatment suppressed CKD-induced hypertension and cardiac hypertrophy. In CKD mice, cardiac fibrosis was associated with upregulation of UT and vimentin abundance. Inhibition of UT suppressed vimentin amount. Left ventricular mass index in DMTU-treated CKD was less compared with non-treated CKD mice as measured by echocardiography. Nephrectomy was performed in UT-A1/A3 knockout (UT-KO) to further confirm our finding. UT-A1/A3 deletion attenuates the CKD-induced increase in cardiac fibrosis and hypertension. The amount of α-smooth muscle actin and tgf-β were significantly less in UT-KO with CKD than WT/CKD mice. To study the possibility that UT inhibition could benefit heart, we measured the mRNA of renin and angiotensin-converting enzyme (ACE), and found both were sharply increased in CKD heart; DMTU treatment and UT-KO significantly abolished these increases. Conclusion: Inhibition of UT reduced hypertension, cardiac fibrosis, and improved heart function. These changes are accompanied by inhibition of renin and ACE.
Collapse
Affiliation(s)
- Akihiro Kuma
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
- Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Xiaonan H. Wang
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Janet D. Klein
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Lin Tan
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Nawazish Naqvi
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Fitra Rianto
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Ying Huang
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Manshu Yu
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
- Renal Division, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Jeff M. Sands
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| |
Collapse
|
6
|
Rianto F, Kuma A, Ellis CL, Hassounah F, Rodriguez EL, Wang XH, Sands JM, Klein JD. UT-A1/A3 knockout mice show reduced fibrosis following unilateral ureteral obstruction. Am J Physiol Renal Physiol 2020; 318:F1160-F1166. [PMID: 32174141 PMCID: PMC7294340 DOI: 10.1152/ajprenal.00008.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/24/2020] [Accepted: 03/12/2020] [Indexed: 12/23/2022] Open
Abstract
Renal fibrosis is a major contributor to the development and progression of chronic kidney disease. A low-protein diet can reduce the progression of chronic kidney disease and reduce the development of renal fibrosis, although the mechanism is not well understood. Urea reabsorption into the inner medulla is regulated by inner medullary urea transporter (UT)-A1 and UT-A3. Inhibition or knockout of UT-A1/A3 will reduce interstitial urea accumulation, which may be beneficial in reducing renal fibrosis. To test this hypothesis, the effect of unilateral ureteral obstruction (UUO) was compared in wild-type (WT) and UT-A1/A3 knockout mice. UUO causes increased extracellular matrix associated with increases in transforming growth factor-β, vimentin, and α-smooth muscle actin (α-SMA). In WT mice, UUO increased the abundance of three markers of fibrosis: transforming growth factor-β, vimentin, and α-SMA. In contrast, in UT-A1/A3 knockout mice, the increase following UUO was significantly reduced. Consistent with the Western blot results, immunohistochemical staining showed that the levels of vimentin and α-SMA were increased in WT mice with UUO and that the increase was reduced in UT-A1/A3 knockout mice with UUO. Masson's trichrome staining showed increased collagen in WT mice with UUO, which was reduced in UT-A1/A3 knockout mice with UUO. We conclude that reduced UT activity reduces the severity of renal fibrosis following UUO.
Collapse
Affiliation(s)
- Fitra Rianto
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Akihiro Kuma
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
- Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Carla L Ellis
- Department of Pathology, Emory University School of Medicine, Atlanta, Georgia
| | - Faten Hassounah
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Eva L Rodriguez
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Xiaonan H Wang
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Jeff M Sands
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Janet D Klein
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| |
Collapse
|
7
|
Rogers RT, Sun MA, Yue Q, Bao HF, Sands JM, Blount MA, Eaton DC. Lack of urea transporters, UT-A1 and UT-A3, increases nitric oxide accumulation to dampen medullary sodium reabsorption through ENaC. Am J Physiol Renal Physiol 2019; 316:F539-F549. [PMID: 30539654 PMCID: PMC6459308 DOI: 10.1152/ajprenal.00166.2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 11/19/2018] [Accepted: 11/30/2018] [Indexed: 12/31/2022] Open
Abstract
Although the role of urea in urine concentration is known, the effect of urea handling by the urea transporters (UTs), UT-A1 and UT-A3, on sodium balance remains elusive. Serum and urinary sodium concentration is similar between wild-type mice (WT) and UT-A3 null (UT-A3 KO) mice; however, mice lacking both UT-A1 and UT-A3 (UT-A1/A3 KO) have significantly lower serum sodium and higher urinary sodium. Protein expression of renal sodium transporters is unchanged among all three genotypes. WT, UT-A3 KO, and UT-A1/A3 KO acutely respond to hydrochlorothiazide and furosemide; however, UT-A1/A3 KO fail to show a diuretic or natriuretic response following amiloride administration, indicating that baseline epithelial Na+ channel (ENaC) activity is impaired. UT-A1/A3 KO have more ENaC at the apical membrane than WT mice, and single-channel analysis of ENaC in split-open inner medullary collecting duct (IMCD) isolated in saline shows that ENaC channel density and open probability is higher in UT-A1/A3 KO than WT. UT-A1/A3 KO excrete more urinary nitric oxide (NO), a paracrine inhibitor of ENaC, and inner medullary nitric oxide synthase 1 mRNA expression is ~40-fold higher than WT. Because endogenous NO is unstable, ENaC activity was reassessed in split-open IMCD with the NO donor PAPA NONOate [1-propanamine-3-(2-hydroxy-2-nitroso-1-propylhydrazine)], and ENaC activity was almost abolished in UT-A1/A3 KO. In summary, loss of both UT-A1 and UT-A3 (but not UT-A3 alone) causes elevated medullary NO production and salt wasting. NO inhibition of ENaC, despite elevated apical accumulation of ENaC in UT-A1/A3 KO IMCD, appears to be the main contributor to natriuresis in UT-A1/A3 KO mice.
Collapse
Affiliation(s)
- Richard T Rogers
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Michael A Sun
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Qiang Yue
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| | - Hui-Fang Bao
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| | - Jeff M Sands
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| | - Mitsi A Blount
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| | - Douglas C Eaton
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| |
Collapse
|
8
|
Cherezova A, Tomilin V, Buncha V, Zaika O, Ortiz PA, Mei F, Cheng X, Mamenko M, Pochynyuk O. Urinary concentrating defect in mice lacking Epac1 or Epac2. FASEB J 2019; 33:2156-2170. [PMID: 30252533 PMCID: PMC6338637 DOI: 10.1096/fj.201800435r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 08/27/2018] [Indexed: 11/11/2022]
Abstract
cAMP is a universal second messenger regulating a plethora of processes in the kidney. Two downstream effectors of cAMP are PKA and exchange protein directly activated by cAMP (Epac), which, unlike PKA, is often linked to elevation of [Ca2+]i. While both Epac isoforms (Epac1 and Epac2) are expressed along the nephron, their relevance in the kidney remains obscure. We combined ratiometric calcium imaging with quantitative immunoblotting, immunofluorescent confocal microscopy, and balance studies in mice lacking Epac1 or Epac2 to determine the role of Epac in renal water-solute handling. Epac1-/- and Epac2-/- mice developed polyuria despite elevated arginine vasopressin levels. We did not detect major deficiencies in arginine vasopressin [Ca2+]i signaling in split-opened collecting ducts or decreases in aquaporin water channel type 2 levels. Instead, sodium-hydrogen exchanger type 3 levels in the proximal tubule were dramatically reduced in Epac1-/- and Epac2-/- mice. Water deprivation revealed persisting polyuria, impaired urinary concentration ability, and augmented urinary excretion of Na+ and urea in both mutant mice. In summary, we report a nonredundant contribution of Epac isoforms to renal function. Deletion of Epac1 and Epac2 decreases sodium-hydrogen exchanger type 3 expression in the proximal tubule, leading to polyuria and osmotic diuresis.-Cherezova, A., Tomilin, V., Buncha, V., Zaika, O., Ortiz, P. A., Mei, F., Cheng, X., Mamenko, M., Pochynyuk, O. Urinary concentrating defect in mice lacking Epac1 or Epac2.
Collapse
Affiliation(s)
- Alena Cherezova
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Viktor Tomilin
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Vadym Buncha
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Pablo A. Ortiz
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA; and
| | - Fang Mei
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
- Texas Therapeutics Institute, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Mykola Mamenko
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
| |
Collapse
|
9
|
Nawata CM, Pannabecker TL. Mammalian urine concentration: a review of renal medullary architecture and membrane transporters. J Comp Physiol B 2018; 188:899-918. [PMID: 29797052 PMCID: PMC6186196 DOI: 10.1007/s00360-018-1164-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 04/23/2018] [Accepted: 05/14/2018] [Indexed: 01/10/2023]
Abstract
Mammalian kidneys play an essential role in balancing internal water and salt concentrations. When water needs to be conserved, the renal medulla produces concentrated urine. Central to this process of urine concentration is an osmotic gradient that increases from the corticomedullary boundary to the inner medullary tip. How this gradient is generated and maintained has been the subject of study since the 1940s. While it is generally accepted that the outer medulla contributes to the gradient by means of an active process involving countercurrent multiplication, the source of the gradient in the inner medulla is unclear. The last two decades have witnessed advances in our understanding of the urine-concentrating mechanism. Details of medullary architecture and permeability properties of the tubules and vessels suggest that the functional and anatomic relationships of these structures may contribute to the osmotic gradient necessary to concentrate urine. Additionally, we are learning more about the membrane transporters involved and their regulatory mechanisms. The role of medullary architecture and membrane transporters in the mammalian urine-concentrating mechanism are the focus of this review.
Collapse
Affiliation(s)
- C Michele Nawata
- Department of Physiology, Banner University Medical Center, University of Arizona, 1501 N. Campbell Avenue, Tucson, AZ, 85724-5051, USA.
| | - Thomas L Pannabecker
- Department of Physiology, Banner University Medical Center, University of Arizona, 1501 N. Campbell Avenue, Tucson, AZ, 85724-5051, USA
| |
Collapse
|
10
|
Lee S, Cil O, Diez-Cecilia E, Anderson MO, Verkman AS. Nanomolar-Potency 1,2,4-Triazoloquinoxaline Inhibitors of the Kidney Urea Transporter UT-A1. J Med Chem 2018; 61:3209-3217. [PMID: 29589443 PMCID: PMC5976253 DOI: 10.1021/acs.jmedchem.8b00343] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Urea transporter A (UT-A) isoforms encoded by the Slc14a2 gene are expressed in kidney tubule epithelial cells, where they facilitate urinary concentration. UT-A1 inhibition is predicted to produce a unique salt-sparing diuretic action in edema and hyponatremia. Here we report the discovery of 1,2,4-triazoloquinoxalines and the analysis of 37 synthesized analogues. The most potent compound, 8ay, containing 1,2,4-triazolo[4,3- a]quinoxaline-substituted benzenesulfonamide linked by an aryl ether, rapidly and reversibly inhibited UT-A1 urea transport by a noncompetitive mechanism with IC50 ≈ 150 nM; the IC50 was ∼2 μM for the related urea transporter UT-B encoded by the Slc14a1 gene. Molecular modeling suggested a putative binding site on the UT-A1 cytoplasmic domain. In vitro metabolism showing quinoxaline ring oxidation prompted the synthesis of metabolically stable 7,8-difluoroquinoxaline analogue 8bl, which when administered to rats produced marked diuresis and reduced urinary osmolality. 8bl has substantially improved UT-A1 inhibition potency and metabolic stability compared with prior compounds.
Collapse
Affiliation(s)
- Sujin Lee
- Departments of Medicine and Physiology, University of California, San Francisco, California 94143-0521, United States
| | - Onur Cil
- Departments of Medicine and Physiology, University of California, San Francisco, California 94143-0521, United States
- Department of Pediatrics, Division of Nephrology, University of California, San Francisco, California 94143-0521, United States
| | - Elena Diez-Cecilia
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, California 94132-1722, United States
| | - Marc O. Anderson
- Departments of Medicine and Physiology, University of California, San Francisco, California 94143-0521, United States
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, California 94132-1722, United States
| | - Alan S. Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, California 94143-0521, United States
| |
Collapse
|
11
|
Jiang T, Li Y, Layton AT, Wang W, Sun Y, Li M, Zhou H, Yang B. Generation and phenotypic analysis of mice lacking all urea transporters. Kidney Int 2017; 91:338-351. [PMID: 27914708 PMCID: PMC5423716 DOI: 10.1016/j.kint.2016.09.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 08/30/2016] [Accepted: 09/08/2016] [Indexed: 01/22/2023]
Abstract
Urea transporters (UT) are a family of transmembrane urea-selective channel proteins expressed in multiple tissues and play an important role in the urine concentrating mechanism of the mammalian kidney. UT inhibitors have diuretic activity and could be developed as novel diuretics. To determine if functional deficiency of all UTs in all tissues causes physiological abnormality, we established a novel mouse model in which all UTs were knocked out by deleting an 87 kb of DNA fragment containing most parts of Slc14a1 and Slc14a2 genes. Western blot analysis and immunofluorescence confirmed that there is no expression of urea transporter in these all-UT-knockout mice. Daily urine output was nearly 3.5-fold higher, with significantly lower urine osmolality in all-UT-knockout mice than that in wild-type mice. All-UT-knockout mice were not able to increase urinary urea concentration and osmolality after water deprivation, acute urea loading, or high protein intake. A computational model that simulated UT-knockout mouse models identified the individual contribution of each UT in urine concentrating mechanism. Knocking out all UTs also decreased the blood pressure and promoted the maturation of the male reproductive system. Thus, functional deficiency of all UTs caused a urea-selective urine-concentrating defect with little physiological abnormality in extrarenal organs.
Collapse
Affiliation(s)
- Tao Jiang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Yingjie Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina, USA
| | - Weiling Wang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Yi Sun
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Min Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Hong Zhou
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Baoxue Yang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China; Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, China.
| |
Collapse
|
12
|
Abstract
PURPOSE OF REVIEW Urea is transported by urea transporter proteins in kidney, erythrocytes, and other tissues. Mice in which different urea transporters have been knocked out have urine-concentrating defects, which has led to the development and testing of urea transporters Slc14A2 (UT-A) and Slc14A1 (UT-B) inhibitors as urearetics. This review summarizes the knowledge gained during the past year on urea transporter regulation and investigations into the clinical potential of urearetics. RECENT FINDINGS UT-A1 undergoes several posttranslational modifications that increase its function by increasing UT-A1 accumulation in the apical plasma membrane. UT-A1 is phosphorylated by protein kinase A, exchange protein activated by cyclic AMP, protein kinase Cα, and AMP-activated protein kinase, all at different serine residues. UT-A1 is also regulated by 14-3-3, which contributes to UT-A1 removal from the membrane. UT-A1 is glycosylated with various glycan moieties in animal models of diabetes mellitus. Transgenic expression of UT-A1 into UT-A1/UT-A3 knockout mice restores urine-concentrating ability. UT-B is present in descending vasa recta and urinary bladder, and is linked to bladder cancer. Inhibitors of UT-A and UT-B have been developed that result in diuresis with fewer abnormalities in serum electrolytes than conventional diuretics. SUMMARY Urea transporters play critical roles in the urine-concentrating mechanism. Urea transport inhibitors are a promising new class of diuretic agent.
Collapse
Affiliation(s)
- Janet D Klein
- Renal Division, Department of Medicine, and Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
| | | |
Collapse
|
13
|
Qian X, Sands JM, Song X, Chen G. Modulation of kidney urea transporter UT-A3 activity by alpha2,6-sialylation. Pflugers Arch 2016; 468:1161-1170. [PMID: 26972907 PMCID: PMC4945389 DOI: 10.1007/s00424-016-1802-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/16/2016] [Accepted: 02/23/2016] [Indexed: 10/22/2022]
Abstract
Two urea transporters, UT-A1 and UT-A3, are expressed in the kidney terminal inner medullary collecting duct (IMCD) and are important for the production of concentrated urine. UT-A1, as the largest isoform of all UT-A urea transporters, has gained much attention and been extensively studied; however, the role and the regulation of UT-A3 are less explored. In this study, we investigated UT-A3 regulation by glycosylation modification. A site-directed mutagenesis verified a single glycosylation site in UT-A3 at Asn279. Loss of the glycosylation reduced forskolin-stimulated UT-A3 cell membrane expression and urea transport activity. UT-A3 has two glycosylation forms, 45 and 65 kDa. Using sugar-specific binding lectins, the UT-A3 glycosylation profile was examined. The 45-kDa form was pulled down by lectin concanavalin A (Con A) and Galant husnivalis lectin (GNL), indicating an immature glycan with a high amount of mannose (Man), whereas the 65-kDa form is a mature glycan composed of acetylglucosamine (GlcNAc) and poly-N-acetyllactosame (poly-LacNAc) that was pulled down by wheat germ agglutinin (WGA) and tomato lectin, respectively. Interestingly, the mature form of UT-A3 glycan contains significant amounts of sialic acid. We explored the enzymes responsible for directing UT-A3 sialylation. Sialyltransferase ST6GalI, but not ST3GalIV, catabolizes UT-A3 α2,6-sialylation. Activation of protein kinase C (PKC) by PDB treatment promoted UT-A3 glycan sialylation and membrane surface expression. The PKC inhibitor chelerythrine blocks ST6GalI-induced UT-A3 sialylation. Increased sialylation by ST6GalI increased UT-A3 protein stability and urea transport activity. Collectively, our study reveals a novel mechanism of UT-A3 regulation by ST6GalI-mediated sialylation modification that may play an important role in kidney urea reabsorption and the urinary concentrating mechanism.
Collapse
Affiliation(s)
- Xiaoqian Qian
- Department of Physiology, Emory University, Atlanta, GA 30322, USA
- Cardiovascular Center, the 4 affiliated hospital, Harbin Medical University, Heilongjiang 150001, China
| | - Jeff M. Sands
- Department of Physiology, Emory University, Atlanta, GA 30322, USA
- Renal Division, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Xiang Song
- Cardiovascular Center, the 4 affiliated hospital, Harbin Medical University, Heilongjiang 150001, China
| | - Guangping Chen
- Department of Physiology, Emory University, Atlanta, GA 30322, USA
- Renal Division, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| |
Collapse
|