Endocrine Abstracts (2013) 31 P3

Mutations in CLC-5 cause disturbances in cytoskeletal dynamics and solute transport in Dent's disease renal proximal tubule cell-lines

Caroline Gorvin1, Sian Piret1, Dilair Baban2, Martijn Wilmer3, Lambertus van den Heuvel4,5, Elena Levtchenko4,5 & Rajesh Thakker1


Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Oxford, UK, 2Genomics Group, The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK, 3Department of Pharmacology and Toxicology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Sciences, Nijmegen, The Netherlands, 4Laboratory of Genetic, Endocrine and Metabolic Disorders, Department of Paediatric Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands, 5Department of Development and Regeneration, Catholic University Leuven, Leuven, Belgium.


Dent’s disease is a renal proximal tubular Fanconi disorder characterised by generalised loss of solutes incuding insulin, glucose, PTH, amino acids and vitamin-D binding protein and is associated with rickets in 25% and phosphaturia in ~40% of patients. Dent’s disease is caused by mutations in the chloride/proton antiporter CLC-5, which, with megalin and cubilin has a role in receptor-mediated endocytosis and vesicle trafficking. To further elucidate the role of CLC-5 in endosomal trafficking, we performed gene expression profiling using Illumina’s Human-HT2v4 BeadChip utilising three human conditionally-immortalised proximal tubular epithelial cell-lines (ciPTECs) that harboured one of three CLC-5 mutations: an in-frame histidine insertion at codon 30 (30:insHis), a deletion of codons 132 to 241 (del132–241) and a nonsense mutation (Arg637Stop) (n=5 for each ciPTEC). Differentially expressed genes with a minimal fold-change of 1.5 and a P<0.05 were further analysed. Sixty-seven genes were differentially expressed in all three Dent’s disease ciPTECs, and individually, the ciPTECs had 107 (30:insHis), 272 (del132-241) and 375 (Arg637Stop) differentially expressed genes. Pathway analysis revealed that two functional pathways, which involved endocytosis/actin dynamics and solute transport, were commonly affected. Quantitative PCR and Western blot analysis confirmed that promoters of actin polymerization were upregulated and inhibitors of actin polymerisation were downregulated in Dent’s disease ciPTECs; these would lead to increased plasma membrane directed vesicular movement, and reduced trafficking from membrane to early endosome. In addition, several small GTPases that regulate early endosomal trafficking were downregulated. Furthermore, Dent’s disease ciPTECs had decreased expression of a number of solute transport genes including SLC38A5, an amino acid transporter, and glucose transporters, which may contribute to the observed aminoaciduria and glycosuria in patients. Investigation of these dysregulated pathways may help to elucidate the mechanisms by which CLC-5 mutations cause Dent’s disease.

Declaration of funding: Yes.

Details: This work was supported by the Medical Research Council (grants G9825289 and G1000467), Kidney Research UK (KRUK), EuFP6-EuReGene, (05085) and Fund for Scientific Research, Flanders (Fundamental Clinical Investigatorship, 1801110N).

DOI: 10.1530/endoabs.31.P3

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