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Role of CLC-5 in renal endocytosis is unique among CLC exchangers and does not require py-motif-dependent ubiquitylation

Item Type:Article
Title:Role of CLC-5 in renal endocytosis is unique among CLC exchangers and does not require py-motif-dependent ubiquitylation
Creators Name:Rickheit, G., Wartosch, L., Schaffer, S., Stobrawa, S., Novarino, G., Weinert, S. and Jentsch, T.J.
Abstract:Inactivation of the mainly endosomal 2Cl-/H+-exchanger ClC-5 severely impairs endocytosis in renal proximal tubules and underlies the human kidney stone disorder Dent's disease. In heterologous expression systems, interaction of the E3 ubiquitin ligases WWP2 and Nedd4-2 with a 'PY-motif' in the cytoplasmic carboxy-terminus of ClC-5 stimulates its internalization from the plasma membrane and may influence receptor-mediated endocytosis. We asked whether this interaction is relevant in vivo and generated mice in which the 'PY-motif' was destroyed by a point mutation. Unlike ClC-5 knock-out mice, these knock-in mice displayed neither low-molecular weight proteinuria nor hyperphosphaturia and both receptor-mediated and fluid-phase endocytosis were normal. The abundances and localizations of the endocytic receptor megalin and of the Na+-coupled phosphate transporter NaPi-2a (Npt2) were not changed, either. To explore whether the discrepancy to results from heterologous expression studies might be due to heteromerization of ClC-5 with ClC-3 or ClC-4 in vivo, we studied knock-in mice additionally deleted for those related transporters. Disruption of neither ClC-3 nor ClC-4 led to proteinuria or impaired proximal tubular endocytosis by itself, nor in combination with the PY-mutant of ClC-5. Endocytosis of cells lacking ClC-5 was not impaired further when ClC-3 or ClC-4 were additionally deleted. We conclude that ClC-5 is unique among CLC proteins in being crucial for proximal tubular endocytosis and that PY-motif-dependent ubiquitylation of ClC-5 is dispensable for this role.
Keywords:Chloride Channels, Endocytosis, Kidney Metabolism, Membrane Trafficking, Mouse Genetics, WW-Domain, Anion/Proton Antiporter, Endosomal Acidification, Animals, Mice
Source:Journal of Biological Chemistry
Publisher:American Society for Biochemistry and Molecular Biology
Page Range:17595-17603
Date:4 June 2010
Official Publication:https://doi.org/10.1074/jbc.M110.115600
PubMed:View item in PubMed

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