Localization of NBC-1 variants in human kidney and renal cell carcinoma.
The Na(+)-HCO(3)(-) cotransporter (NBC-1) plays a major role in bicarbonate absorption from proximal tubules. However, which NBC-1 variant mediates proximal bicarbonate absorption has not been definitely determined. Moreover, the localization of this cotransporter in human kidney and renal cell carcinoma (RCC) tissues has not been clarified. To clarify these issues, immunohistochemical analysis was performed using the specific antibodies against kidney type (kNBC-1) and pancreatic type (pNBC-1) transporters. In Western blot analysis the expression of kNBC-1 but not of pNBC-1 was detected in both normal human kidney and RCC tissues. In immunofluorescence analysis on normal renal tissues the anti-kNBC-1 antibody strongly and exclusively labeled the basolateral membranes of proximal tubules, which was confirmed by electron microscopic observation. In RCC cells, the anti-kNBC-1 antibody labeled both plasma membranes and intracellular organelles. The labeling by anti-pNBC-1 antibody was not detected in both normal kidney and RCC tissues. These results indicate that kNBC-1 is the dominant variant that mediates bicarbonate absorption from human renal proximal tubules. They also suggest that NBC-1 may have distinct roles in cancer cells.
Yamada
Hideomi
H
Department of Internal Medicine, Faculty of Medicine, Tokyo University, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Yamazaki
Satoru
S
Moriyama
Nobuo
N
Hara
Chiaki
C
Horita
Shoko
S
Enomoto
Yutaka
Y
Kudo
Akihiko
A
Kawakami
Hayato
H
Tanaka
Yoshinori
Y
Fujita
Toshiro
T
Seki
George
G
D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D002292:Carcinoma, Renal Cell / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism* / Q000648:ultrastructure; D007680:Kidney Neoplasms / Q000378:metabolism*; D008854:Microscopy, Electron; D008875:Middle Aged; D027982:Sodium-Bicarbonate Symporters / Q000378:metabolism*
C498898:SLC4A4 protein, human; D027982:Sodium-Bicarbonate Symporters