1. Uncoupling endosomal CLC chloride/proton exchange causes severe neurodegeneration.
- Author
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Weinert, Stefanie, Gimber, Niclas, Deuschel, Dorothea, Stuhlmann, Till, Puchkov, Dmytro, Farsi, Zohreh, Ludwig, Carmen F, Novarino, Gaia, López‐Cayuqueo, Karen I, Planells‐Cases, Rosa, and Jentsch, Thomas J
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HETERODIMERS , *SYNAPTIC vesicles , *CENTRAL nervous system , *NEURODEGENERATION , *CHLORIDES - Abstract
CLC chloride/proton exchangers may support acidification of endolysosomes and raise their luminal Cl− concentration. Disruption of endosomal ClC‐3 causes severe neurodegeneration. To assess the importance of ClC‐3 Cl−/H+ exchange, we now generate Clcn3unc/unc mice in which ClC‐3 is converted into a Cl− channel. Unlike Clcn3−/− mice, Clcn3unc/unc mice appear normal owing to compensation by ClC‐4 with which ClC‐3 forms heteromers. ClC‐4 protein levels are strongly reduced in Clcn3−/−, but not in Clcn3unc/unc mice because ClC‐3unc binds and stabilizes ClC‐4 like wild‐type ClC‐3. Although mice lacking ClC‐4 appear healthy, its absence in Clcn3unc/unc/Clcn4−/− mice entails even stronger neurodegeneration than observed in Clcn3−/− mice. A fraction of ClC‐3 is found on synaptic vesicles, but miniature postsynaptic currents and synaptic vesicle acidification are not affected in Clcn3unc/unc or Clcn3−/− mice before neurodegeneration sets in. Both, Cl−/H+‐exchange activity and the stabilizing effect on ClC‐4, are central to the biological function of ClC‐3. Synopsis: The importance of intracellular ClC‐3 channel conductance versus chloride/proton exchange activity for endosome and synaptic vesicle function remain unclear. Here, study of a new ClC‐3 uncoupling mouse mutant (Clcn3unc/unc) reveals that proton transport by ClC‐3/ClC‐4 heterodimers is crucial for central nervous system integrity. Clcn3unc/unc mice devoid of channel function do not exhibit neurodegeneration.ClC‐3 forms heterodimers with ClC‐4 and stabilizes it.Depletion of ClC‐4 in Clcn3unc/unc mice causes severe neurodegeneration.ClC‐3 has no functional role in synaptic vesicles. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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