Establishment and Analysis of SLC22A12 (URAT1) Knockout Mouse

Nucleosides, Nucleotides and Nucleic Acids

Takiue

Saito

et al. 2011

To elucidate the mechanism of obesity/metabolic syndrome-related hyperuricemia, this study aimed to determine the expression levels of transport systems for urate absorption (Urat1, Smct1, Glut9) and urate secretion (Abcg2). The kidneys of two obesity models in mice were used: 1) leptin-deficient mice (ob/ob mice) and 2) Quick fat diet model. 1) 8-week-old male ob/ob mice demonstrated the increased protein levels of Slc22a12 (Urat1), Slc2a9 (Glut9), and Abcg2 (Abcg2) and a decreased protein level of Slc5a8 (Smct1). However, no significant changes in the mRNA levels of these genes were observed. 2) C57BL/6 mice were fed with a Quick fat diet (crude fat content: 13.6%) from the age of 24 to 28 weeks (Quick fat diet group). The average body weights of the Quick fat diet group were heavier than those of the control group fed with a normal diet (crude fat content: 4.8%). The mRNA levels of Slc22a12, Slc2a9, Abcg2, or Slc5a8 did not change significantly in both groups. The protein levels of Slc22a12 (Urat1) and Abcg2 (Abcg2) increased significantly in the Quick fat diet group. Those of Slc2a9 (Glut9) and Slc5a8 (Smct1) were not changed significantly in the Quick fat diet group. In conclusion, the Quick fat diet enhanced the protein levels of Urat1 and Abcg2 without any changes in their mRNA transcription levels. The cause of obesity/metabolic syndrome-associated hyperuricemia appears to be associated with the urate reabsorption transporter Urat1 protein enhanced by fat.

Section: Methodsmentioning

confidence: 99%

The Increased Protein Level of URAT1 was Observed in Obesity/Metabolic Syndrome Model Mice

Nucleosides, Nucleotides and Nucleic Acids

Takiue

Saito

et al. 2011

“…Male C57BL/6 J mice (Sankyo Laboratories, Tokyo, Japan) and homozygous URAT1 knockout mice [17] were maintained under a 14:10 light cycle with free access to food and water. For this study, 8–10 mice were used in each group.…”

Section: Methodsmentioning

confidence: 99%

“…In the present study, we investigated the distribution of URAT1 in mouse brain by immunohistochemical analysis using an anti-URAT1 antibody [17], the specificity of which was confirmed using a URAT1 knockout mouse.…”

Section: Introductionmentioning

confidence: 99%

Ependymal cells of the mouse brain express urate transporter 1 (URAT1)

Tomioka

Deguchi

et al. 2013

Fluids Barriers CNS

BackgroundElevated uric acid (UA) is commonly associated with gout and it is also a known cardiovascular disease risk factor. In contrast to such deleterious effects, UA possesses neuroprotective properties in the brain and elucidating the molecular mechanisms involved may have significant value regarding the therapeutic treatment of neurodegenerative disease. However, it is not yet fully established how UA levels are regulated in the brain. In this study, we investigated the distribution of mouse urate transporter 1 (URAT1) in the brain. URAT1 is a major reabsorptive urate transporter predominantly found in the kidney.MethodsImmunohistochemistry of wild type and URAT1 knockout mouse brain using paraffin or frozen sections and a rabbit polyclonal anti-mouse URAT1 antibody were employed.ResultsAntibody specificity was confirmed by the lack of immunostaining in brain tissue from URAT1 knockout mice. URAT1 was distributed throughout the ventricular walls of the lateral ventricle, dorsal third ventricle, ventral third ventricle, aqueduct, and fourth ventricle, but not in the non-ciliated tanycytes in the lower part of the ventral third ventricle. URAT1 was localized to the apical membrane, including the cilia, of ependymal cells lining the wall of the ventricles that separates cerebrospinal fluid (CSF) and brain tissue.ConclusionIn this study, we report that URAT1 is expressed on cilia and the apical surface of ventricular ependymal cells. This is the first report to demonstrate expression of the urate transporter in ventricular ependymal cells and thus raises the possibility of a novel urate transport system involving CSF.

“…Serum and urinary creatinine was assayed using HPlC as described previously. 5) All animal experiments were carried out in accordance with Teikyo University Guide for the Care and Use of laboratory Animals.…”

Section: Methodsmentioning

confidence: 99%

Macrophage Migration Inhibitory Factor Is a Possible Candidate for the Induction of Microalbuminuria in Diabetic db/db Mice

Watanabe

Tomioka

Biological & Pharmaceutical Bulletin

et al. 2013

Preventing the onset of microalbuminuria in diabetic nephropathy is a problem that needs urgent rectification. The use of a mouse model for diabetes is vital in this regard. For example, db/db mice exhibit defects in the leptin receptor Ob-Rb sub-type, while the ob/ob strain exhibits defects in the leptin ligand. These mouse strains demonstrate type 2 diabetes, either with or without microalbuminuria, respectively. The purpose of the present study was to use DNA microarray technology to screen for the gene responsible for the onset of diabetic microalbuminuria. Using Affymetrix Mouse Gene ST 1.0 arrays, microarray analysis was performed using total RNA from the kidneys of ob control, ob/ob, db/m, and db/db mice. Microarray and quantitative reverse transcription-polymerase chain reaction (RT-PCR) indicated that transcription of the macrophage migration inhibitory factor (MIF) gene was significantly enhanced in the kidneys of db/db mice. Western blotting showed that levels of MIF protein was enhanced in the kidneys of both diabetic db/db and ob/ob mice. On the other hand, elevation of urinary MIF excretion detected by enzyme-linked immunosorbent assay (ELISA) was only in db/db mice and preceded the onset of microalbuminuria. Immunofluorescence studies revealed that MIF was expressed in mouse kidney glomeruli. While MIF expression was enhanced in the diabetic kidneys of both mouse strains, the elevated secretion from db/db mouse kidneys may be responsible for initiating the onset of microalbuminuria in diabetic nephropathy.Key words macrophage migration inhibitory factor; diabetic nephropathy; microalbuminuria; db/db mouse; ob/ob mouse Diabetic nephropathy is the primary causative disease leading to dialysis in Japan.1) The cumulative incidence of nephropathy after 30 years of post-pubertal diabetes was reported to be significantly higher in type 2 diabetic patients (44.4%) than in type 1 diabetic patients (20.2%).2) However, diabetic nephropathy does not occur in all patients with type 2 diabetes mellitus, implying that there might be an unknown underlying mechanism to prevent the onset of diabetic nephropathy. Establishing the identity of such a mechanism is of vital importance.It is thought that the onset of microalbuminuria, considered to be a marker of early diabetic nephropathy, must be suppressed in order to inhibit the onset and aggravation of nephropathy in type 2 diabetes. Two murine strains are available as an animal model for type 2 diabetes: db/db mice in which microalbuminuria develops at 8 weeks of age 3); and ob/ob mice that do not develop microalbuminuria at all. It is thought that a gene cluster associated with the onset of microalbuminuria could therefore be identified by comparing differences in gene expression between these two mouse strains, without considering a specific disease-developing mechanism underlying microalbuminuria.The purpose of this study was therefore to identify a gene associated with the onset of microalbuminuria in the type 2 diabetic model mouse using a DNA microarray appro...