Urate transport via human PAH transporter hOAT1 and its gene structure.
BACKGROUND
We recently cloned the human organic anion transporter 1 (hOAT1) as a p-aminohippurate (PAH) transporter. Whether urate is transported by the PAH transporter in humans remains unclear. Familial juvenile gouty nephropathy (FJGN) is thought to develop as a result of an abnormality in the urate transporter.


METHODS
To determine if hOAT1 transported urate, the cellular uptakes of PAH and urate were determined, as were the inhibition profiles of inorganic anions, and uricosuric and antiuricosuric agents using a mouse S2 cell line expressing hOAT1. The hOAT1 gene was cloned from a genomic library using full-length hOAT1-1 cDNA as a probe. The coding regions of the hOAT1 genes of two sisters with FJGN were sequenced. Also, immunohistochemical fluorescence analysis of hOAT1 in the kidney of the younger sister with FJGN was performed.


RESULTS
The Km and Vmax values of urate transport via hOAT1 were 943 +/- 84 micromol/L and 1286 +/- 162 pmol/mg protein/min, respectively. The order of the IC50 of urate transport via hOAT1 was benzbromarone < probenecid < salicylate or pyrazine carboxylic acid. The 10.9 kb hOAT1 gene was found to be interrupted by nine introns. Mutations in the coding region of the hOAT1 gene from the two sisters with FJGN were undetectable. Immunohistochemical fluorescent staining showed that hOAT1 in the kidney of the younger sister was similar to that of control individuals.


CONCLUSIONS
Our data show that hOAT1 transports urate, and the inhibition profiles of uricosuric and antiuricosuric agents are defined. hOAT1 is not responsible for FJGN in the two sisters examined in this study.
Ichida
Kimiyoshi
K
Department of Internal Medicine, Jikei University School of Medicine, Kyorin University School of Medicine, Tokyo, Japan.
Hosoyamada
Makoto
M
Kimura
Hiroaki
H
Takeda
Michio
M
Utsunomiya
Yasunori
Y
Hosoya
Tatsuo
T
Endou
Hitoshi
H
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001553:Benzbromarone / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D002250:Carbon Radioisotopes; D002460:Cell Line; D003001:Cloning, Molecular; D005091:Exons; D005260:Female; D015723:Gene Library; D006073:Gout / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000378:metabolism; D007674:Kidney Diseases / Q000235:genetics* / Q000378:metabolism; D027362:Organic Anion Transport Protein 1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011339:Probenecid / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D011718:Pyrazinamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D012980:Sodium Salicylate / Q000494:pharmacology; D014527:Uric Acid / Q000378:metabolism*; D014528:Uricosuric Agents / Q000494:pharmacology; D010130:p-Aminohippuric Acid / Q000493:pharmacokinetics
D000894:Anti-Inflammatory Agents, Non-Steroidal; D002250:Carbon Radioisotopes; D027362:Organic Anion Transport Protein 1; D014528:Uricosuric Agents; D014527:Uric Acid; D011718:Pyrazinamide; C005296:pyrazinoic acid; D001553:Benzbromarone; D011339:Probenecid; D012980:Sodium Salicylate; D010130:p-Aminohippuric Acid