Files and links (2)
Published VersionCC BY V4.0, Open Access
Published VersionCC BY V4.0, Open
Journal article
Regulation of albumin endocytosis by PSD95/Dlg/ZO-1 (PDZ) scaffolds: Interaction of Na-H exchange regulatory factor-2 with ClC-5
Journal of Biological Chemistry, Vol.281(23), pp.16068-16077
2006
PMID: 16601121
Abstract
The constitutive reuptake of albumin from the glomerular filtrate by receptor-mediated endocytosis is a key function of the renal proximal tubules. Both the Cl- channel ClC-5 and the Na+-H+ exchanger isoform 3 are critical components of the macromolecular endocytic complex that is required for albumin uptake, and therefore the cell-surface levels of these proteins may limit albumin endocytosis. This study was undertaken to investigate the potential roles of the epithelial PDZ scaffolds, Na+-H+ exchange regulatory factors, NHERF1 and NHERF2, in albumin uptake by opossum kidney (OK) cells. We found that ClC-5 co-immunoprecipitates with NHERF2 but not NHERF1 from OK cell lysate. Experiments using fusion proteins demonstrated that this was a direct interaction between an internal binding site in the C terminus of ClC-5 and the PDZ2 module of NHERF2. In OK cells, NHERF2 is restricted to the intravillar region while NHERF1 is located in the microvilli. Silencing NHERF2 reduced both cell-surface levels of ClC-5 and albumin uptake. Conversely, silencing NHERF1 increased cell-surface levels of ClC-5 and albumin uptake, presumably by increasing the mobility of NHE3 in the membrane and its availability to the albumin uptake complex. Surface biotinylation experiments revealed that both NHERF1 and NHERF2 were associated with the plasma membrane and that NHERF2 was recruited to the membrane in the presence of albumin. The importance of the interaction between NHERF2 and the cytoskeleton was demonstrated by a significant reduction in albumin uptake in cells overexpressing an ezrin binding-deficient mutant of NHERF2. Thus NHERF1 and NHERF2 differentially regulate albumin uptake by mechanisms that ultimately alter the cell-surface levels of ClC-5.
Details
- Title
- Regulation of albumin endocytosis by PSD95/Dlg/ZO-1 (PDZ) scaffolds: Interaction of Na-H exchange regulatory factor-2 with ClC-5
- Authors
- Deanne H. Hryciw - The University of QueenslandJenny Ekberg - The University of QueenslandCharles Ferguson - The University of QueenslandAven Lee - The University of QueenslandDongsheng Wang - Emory UniversityRobert G. Parton - The University of QueenslandCarol A. Pollock - UNSW SydneyChris C. Yun - Emory UniversityPhilip Poronnik (Corresponding Author) - The University of Queensland
- Publication details
- Journal of Biological Chemistry, Vol.281(23), pp.16068-16077
- Publisher
- Elsevier Inc.
- Date published
- 2006
- DOI
- 10.1074/jbc.M512559200
- ISSN
- 1083-351X; 0021-9258
- PMID
- 16601121
- Copyright note
- © 2006 by The American Society for Biochemistry and Molecular Biology, Inc. This is an Open Access article under the CC BY license
- Grant note
- R01 DK061418/DK/NIDDK NIH HHS/United States. This work was supported by grants from the National Health and Medical Research Council of Australia (to P. P., C. A. P., and R. G. P.).
- Organisation Unit
- School of Health - Biomedicine
- Language
- English
- Record Identifier
- 991187227202621
- Output Type
- Journal article
Metrics
1 Record Views