2003 Fiscal Year Final Research Report Summary
The role of Na-HCO_3 cotransporter in metastasis of renal cell carcinoma
| Project/Area Number |
14571486
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Urology
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| Research Institution | Fukuoka Prefectural University (2003)
The University of Tokyo (2002) |
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Principal Investigator |
MORIYAMA Nobuo Fukuoka Prefectural University, Experimental Nursing, Professor, 看護学部, 教授 (80143501)
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| Co-Investigator(Kenkyū-buntansha) |
SEKI George The University of Tokyo, Urology, Assistant Professor, 医学部附属病院, 講師 (30206619)
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| Project Period (FY) |
2002 – 2003
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| Keywords | renal tubules / Na-HCO3-cotransporter / renal tubular acidosis / SLC4A4 / Xenopus oocyte |
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| Research Abstract |
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 determined. Moreover, the localization of this cotransporter in human kidney, renal cell carcinoma (RCC) tissues, and rat kidney has not been clarified. To clarify them, 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 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. 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.
Then, we determined the localization of NBC-1 variants in rat kidney. In Western blot analysis of rat kidney both anti-kNBC-1 and anti-pNBC-1 antibodies yielded a 130 kDa band. In immunohistochemical analysis the anti-kNBC-1 antibody produced a strong and exclusively basolateral labeling in proximal tubules. On the other hand, the occasional pNBC-1 labeling was detected in the apical membranes of proximal tubules. The basolateral localization of kNBC-1 as well as the localization of pNBC-1 on the basis of the brush border was further supported by electron microscopic observation.
These results are consistent with a view that kNBC-1 is the dominant variant that mediates bicarbonate reabsorption from human and rat renal proximal tubules. They also suggest that NBC-1 may have distinct roles in cancer cells.
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