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Cl - and H + coupling properties and subcellular localizations of wildtype and disease-associated variants of the voltage-gated Cl - /H + exchanger ClC-5
Ist Teil von
The Journal of biological chemistry, 2020-02, Vol.295 (6), p.1464
Ort / Verlag
United States
Erscheinungsjahr
2020
Quelle
Electronic Journals Library
Beschreibungen/Notizen
Dent disease 1 (DD1) is caused by mutations in the CLCN5 gene encoding a voltage-gated electrogenic nCl
/H
exchanger ClC-5. Using ion-selective microelectrodes and Xenopus oocytes, here we studied Cl
/H
coupling properties of WT ClC-5 and four DD1-associated variants (S244L, R345W, Q629*, and T657S), along with trafficking and localization of ClC-5. WT ClC-5 had a 2Cl
/H
exchange ratio at a V
of +40 mV with a [Cl
]
of 104 mm, but the transport direction did not reverse with a [Cl
]
of 5 mm, indicating that ClC-5-mediated exchange of two Cl
out for one H
in is not permissible. We hypothesized that ClC-5 and H
-ATPase are functionally coupled during H
-ATPase-mediated endosomal acidification, crucial for ClC-5 activation by depolarizing endosomes. ClC-5 transport that provides three net negative charges appeared self-inhibitory because of ClC-5's voltage-gated properties, but shunt conductance facilitated further H
-ATPase-mediated endosomal acidification. Thus, an on-and-off "burst" of ClC-5 activity was crucial for preventing Cl
exit from endosomes. The subcellular distribution of the ClC-5:S244L variant was comparable with that of WT ClC-5, but the variant had a much slower Cl
and H
transport and displayed an altered stoichiometry of 1.6:1. The ClC-5:R345W variant exhibited slightly higher Cl
/H
transport than ClC-5:S244L, but co-localized with early endosomes, suggesting decreased ClC-5:R345W membrane trafficking is perhaps in a fully functional form. The truncated ClC-5:Q629* variant displayed the lowest Cl
/H
exchange and was retained in the endoplasmic reticulum and cis-Golgi, but not in early endosomes, suggesting the nonsense mutation affects ClC-5 maturation and trafficking.
Sprache
Englisch
Identifikatoren
eISSN: 1083-351X
Titel-ID: cdi_pubmed_primary_33485541
Format
–
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