Carota, I. and Theilig, F. and Oppermann, M. and Kongsuphol, P. and Rosenauer, A. and Schreiber, R. and Jensen, B. L. and Walter, S. and Kunzelmann, K. and Castrop, H. (2010) Localization and functional characterization of the human NKCC2 isoforms. ACTA PHYSIOLOGICA, 199 (3). pp. 327-337. ISSN 1748-1708,
Full text not available from this repository. (Request a copy)Abstract
Aim: Salt reabsorption across the apical membrane of cells in the thick ascending limb (TAL) of Henle is primarily mediated by the bumetanide-sensitive Na+/K+/2Cl- cotransporter NKCC2. Three full-length splice variants of NKCC2 (NKCC2B, NKCC2A and NKCC2F) have been described. The NKCC2 isoforms have specific localizations and transport characteristics, as assessed for rabbit, rat and mouse. In the present study, we aimed to address the localization and transport characteristics of the human NKCC2 isoforms. Methods: RT-PCR, in situ hybridization and uptake studies in Xenopus oocytes were performed to characterize human NKCC2 isoforms. Results: All three classical NKCC2 isoforms were detected in the human kidney; in addition, we found splice variants with tandem duplicates of the variable exon 4. Contrary to rodents, in which NKCC2F is the most abundant NKCC2 isoform, NKCC2A was the dominant isoform in humans; similarly, isoform-specific in situ hybridization showed high expression levels of human NKCC2A along the TAL. Compared to NKCC2B and NKCC2F, human NKCC2A had the lowest Cl- affinity as determined by 86Rb+ uptake studies in oocytes. All NKCC2 isoforms were more efficiently inhibited by bumetanide than by furosemide. A sequence analysis of the amino acids encoded by exon 4 variants revealed high similarities between human and rodent NKCC2 isoforms, suggesting that differences in ion transport characteristics between species may be related to sequence variations outside the highly conserved sequence encoded by exon 4. Conclusion: The human NKCC2 is an example of how differential splicing forms the basis for a diversification of transporter protein function.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | THICK ASCENDING LIMB; K-CL COTRANSPORTER; NA-K-2CL COTRANSPORTER; BARTTERS-SYNDROME; SPLICE VARIANTS; TRANSPORT; BUMETANIDE; RAT; AFFINITIES; MECHANISMS; differential splicing; human NKCC2; loop diuretics |
| Subjects: | 500 Science > 570 Life sciences 600 Technology > 610 Medical sciences Medicine |
| Divisions: | Medicine > Lehrstuhl für Kinder- und Jugendmedizin Biology, Preclinical Medicine > Institut für Physiologie > Prof. Dr. Karl Kunzelmann Biology, Preclinical Medicine > Institut für Physiologie > Prof. Dr. Wolf Hayo Castrop |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 27 Jul 2020 07:19 |
| Last Modified: | 27 Jul 2020 07:19 |
| URI: | https://pred.uni-regensburg.de/id/eprint/24471 |
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