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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-18876

Reining, S; Gisler, S M; Fuster, D; Moe, O; O'Sullivan, G A; Betz, H; Biber, J; Murer, H; Hernando, N (2009). GABARAP deficiency modulates expression of NaPi-IIa in renal brush-border membranes. American Journal of Physiology. Renal Physiology, 296(5):F1118-F1128.

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Abstract

Renal reabsorption of inorganic phosphate (P(i)) is mainly mediated by the Na(+)-dependent P(i)-cotransporter NaPi-IIa that is expressed in the brush-border membrane (BBM) of renal proximal tubules. Regulation and apical expression of NaPi-IIa are known to depend on a network of interacting proteins. Most of the interacting partners identified so far associate with the COOH-terminal PDZ-binding motif (TRL) of NaPi-IIa. In this study GABA(A) receptor-associated protein (GABARAP) was identified as a novel interacting partner of NaPi-IIa applying a membrane yeast-two-hybrid system (MYTH 2.0) to screen a mouse kidney library with the TRL-truncated cotransporter as bait. GABARAP mRNA and protein are present in renal tubules, and the interaction of NaPi-IIa and GABARAP was confirmed by using glutathione S-transferase pulldowns from BBM and coimmunoprecipitations from transfected HEK293 cells. Amino acids 36-68 of GABARAP were identified as the determinant for the described interaction. The in vivo effects of this interaction were studied in a murine model. GABARAP(-/-) mice have reduced urinary excretion of P(i), higher Na(+)-dependent (32)P(i) uptake in BBM vesicles, and increased expression of NaPi-IIa in renal BBM compared with GABARAP(+/+) mice. The expression of Na(+)/H(+) exchanger regulatory factor (NHERF)1, an important scaffold for the apical expression of NaPi-IIa, is also increased in GABARAP(-/-) mice. The absence of GABARAP does not interfere with the regulation of the cotransporter by either parathyroid hormone or acute changes of dietary P(i) content.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
DDC:570 Life sciences; biology
Language:English
Date:2009
Deposited On:02 Jun 2009 13:13
Last Modified:28 Nov 2013 00:38
Publisher:American Physiological Society
ISSN:0363-6127
Publisher DOI:10.1152/ajprenal.90492.2008
PubMed ID:19225049

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