Dataset Information

PDLIM5 links kidney anion exchanger 1 (kAE1) to ILK and is required for membrane targeting of kAE1.

ABSTRACT: Anion exchanger 1 (AE1) mediates Cl-/HCO3- exchange in erythrocytes and kidney intercalated cells where it functions to maintain normal bodily acid-base homeostasis. AE1's C-terminal tail (AE1C) contains multiple potential membrane targeting/retention determinants, including a predicted PDZ binding motif, which are critical for its normal membrane residency. Here we identify PDLIM5 as a direct binding partner for AE1 in human kidney, via PDLIM5's PDZ domain and the PDZ binding motif in AE1C. Kidney AE1 (kAE1), PDLIM5 and integrin-linked kinase (ILK) form a multiprotein complex in which PDLIM5 provides a bridge between ILK and AE1C. Depletion of PDLIM5 resulted in significant reduction in kAE1 at the cell membrane, whereas over-expression of kAE1 was accompanied by increased PDLIM5 levels, underscoring the functional importance of PDLIM5 for proper kAE1 membrane residency, as a crucial linker between kAE1 and actin cytoskeleton-associated proteins in polarized cells.

SUBMITTER: Su Y

PROVIDER: S-EPMC5206653 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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PDLIM5 links kidney anion exchanger 1 (kAE1) to ILK and is required for membrane targeting of kAE1.

Su Ya Y Hiemstra Thomas F TF Yan Yahui Y Li Juan J Karet Hannah I HI Rosen Lawrence L Moreno Pablo P Karet Frankl Fiona E FE

Scientific reports 20170103

Anion exchanger 1 (AE1) mediates Cl-/HCO3- exchange in erythrocytes and kidney intercalated cells where it functions to maintain normal bodily acid-base homeostasis. AE1's C-terminal tail (AE1C) contains multiple potential membrane targeting/retention determinants, including a predicted PDZ binding motif, which are critical for its normal membrane residency. Here we identify PDLIM5 as a direct binding partner for AE1 in human kidney, via PDLIM5's PDZ domain and t ...[more]

PMID: 28045035

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Project description:Kanadaptin (kidney anion exchanger adaptor protein) has recently been identified as a protein with binding activity to the cytoplasmic domain of the kidney Na(+)-independent Cl(-)/HCO(-)(3) anion exchanger 1 (kAE1). Since it is widely expressed in tissues devoid of kAE1, however, kanadaptin is likely to have additional cellular roles. This is supported by its multidomain structure, and possession of three clusters of basic amino acids exhibiting similarity to known nuclear localization sequences (NLSs). In the present study, we use immunofluorescence and subcellular fractionation approaches to demonstrate that kanadaptin is localized within the nuclei of various epithelial and non-epithelial cultured cell types. The role of the different NLSs is examined in transfection studies using plasmids encoding full-length kanadaptin with or without green fluorescent protein (GFP) as a fusion tag, as well as truncation derivatives thereof. Strong nuclear localization of fusion proteins containing amino acids 140-230 of kanadaptin, which include the sequence AVSRKRKA(193) (NLS1) was observed. Substitution of Arg(191) with a threonine residue resulted in a cytoplasmic location of the expressed protein, while NLS1 proved sufficient to target an otherwise cytoplasmically localized beta-galactosidase-GFP fusion protein to the nucleus. Using a direct binding assay we show that a fusion protein containing kanadaptin amino acids 1-231 (but not the Thr(191) substituted derivative) is recognized with nM affinity by the conventional NLS-binding importin alpha/beta heterodimer. Nuclear import studies on microinjected and permeabilized rat hepatoma cells demonstrated functionality of the NLS in nuclear targeting, with inhibition by antibodies demonstrating the requirement of both importin alpha and beta for nuclear import of kanadaptin. That kanadaptin possesses a functional importin-alpha/beta-recognized NLS explains the nuclear localization of kanadaptin in various cultured cell types, and opens up the possibility that kanadaptin may have a signalling role in the nucleus.

Dataset Information

PDLIM5 links kidney anion exchanger 1 (kAE1) to ILK and is required for membrane targeting of kAE1.

Publications

PDLIM5 links kidney anion exchanger 1 (kAE1) to ILK and is required for membrane targeting of kAE1.

Similar Datasets

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