Gene expression levels and immunolocalization of organic ion transporters in the human kidney.
Renal excretion of organic anions and cations is mediated by the organic ion transporter family (SLC22A). In this study, the mRNA levels of the organic ion transporters were quantified by real-time PCR in normal parts of renal tissues from seven nephrectomized patients with renal cell carcinoma, and the distributions and localization of human (h)OAT1, hOAT3, and hOCT2 proteins were investigated by immunohistochemical analyses in the human kidney. The expression level of hOAT3 mRNA was the highest among the organic ion transporter family, followed by that of hOAT1 mRNA. The hOCT2 mRNA level was the highest in the human OCT family, and the level of hOCTN2 mRNA was higher than that of hOCTN1. hOCT1 mRNA showed the lowest level of expression in organic ion transporter family. hOAT1, hOAT3, and hOCT2 proteins were detected in crude membranes from the kidney of all patients by Western blot analyses, whereas hOCT1 protein could not be detected. Immunohistochemical analyses showed that both hOAT1 and hOAT3 were localized to the basolateral membrane of the proximal tubules in the cortex, and hOCT2 was localized to the basolateral membrane of the proximal tubules in both the cortex and medullary ray. Immunohistochemical analyses of serial sections indicated that hOAT1, hOAT3, and hOCT2 were coexpressed in a portion of the proximal tubules. These results suggest that hOAT1, hOAT3, and hOCT2 play predominant roles in the transport of organic ions across the basolateral membrane of human proximal tubules.
Motohashi
Hideyuki
H
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Sakurai
Yuji
Y
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Saito
Hideyuki
H
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Masuda
Satohiro
S
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Urakami
Yumiko
Y
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Goto
Maki
M
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Fukatsu
Atsushi
A
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Ogawa
Osamu
O
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Inui
Ken-Ichi
KI
*Department of Pharmacy, Division of Artificial Kidneys, and Department of Urology, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto, Japan.
D000368:Aged; D015153:Blotting, Western; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D027361:Organic Anion Transporters / Q000235:genetics* / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014018:Tissue Distribution
D027361:Organic Anion Transporters; D020033:Protein Isoforms; D012333:RNA, Messenger