Cellular and subcellular localization of the vasopressin-regulated urea transporter in rat kidney

被引:163
作者
Nielsen, S
Terris, J
Smith, CP
Hediger, MA
Ecelbarger, CA
Knepper, MA
机构
[1] NHLBI,KIDNEY & ELECTROLYTE METAB LAB,BETHESDA,MD 20892
[2] AARHUS UNIV,DEPT CELL BIOL,DK-8000 AARHUS C,DENMARK
[3] BRIGHAM & WOMENS HOSP,DIV RENAL,BOSTON,MA 02115
[4] HARVARD UNIV,SCH MED,BOSTON,MA 02115
[5] UNIFORMED SERV UNIV HLTH SCI,DEPT PHYSIOL,BETHESDA,MD 20814
关键词
D O I
10.1073/pnas.93.11.5495
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The renal urea transporter (RUT) is responsible for urea accumulation in the renal medulla, and consequently plays a central role in the urinary concentrating mechanism. To study its cellular and subcellular localization, we prepared affinity-purified, peptide-derived polyclonal antibodies against rat RUT based on the cloned cDNA sequence. Immunoblots using membrane fractions from rat renal inner medulla revealed a solitary 97-kDa band. Immunocytochemistry demonstrated RUT labeling of the apical and subapical regions of inner medullary collecting duct (IMCD) cells, with no labeling of outer medullary or cortical collecting ducts. Immunoelectron microscopy directly demonstrated labeling of the apical plasma membrane and of subapical intracellular vesicles of IMCD cells, but no labeling of the basolateral plasma membrane. Immunoblots demonstrated RUT labeling in both plasma membrane and intracellular vesicle-enriched membrane fractions from inner medulla, a subcellular distribution similar to that of the vasopressin-regulated water channel, aquaporin-2.In the outer medulla, RUT labeling was seen in terminal portions of short-loop descending thin limbs. Aside from IMCD and descending thin limbs, no other structures were labeled in the kidney. These results suggest that: (i) the RUT provides the apical pathway for rapid, vasopressin-regulated urea transport in the IMCD, (ii) collecting duct urea transport may be increased by vasopressin by stimulation of trafficking of RUT-containing vesicles to the apical plasma membrane, and (iii) the rat urea transporter may provide a pathway for urea entry into the descending limbs of short-loop nephrons.
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页码:5495 / 5500
页数:6
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