Anno2014
AutoriGradogna, Antonella; Imbrici, Paola; Zifarelli, Giovanni; Liantonio, Antpnella; Camerino, Diana Conte; Pusch, Michael
AbstractCLC-K chloride channels and their subunit, barttin, are crucial for renal NaCl reabsorption and for inner ear endolymph production. Mutations in CLC-Kb and barttin cause Bartter syndrome. Here, we identified two adjacent residues, F256 and N257, that when mutated hugely alter in Xenopus oocytes CLC-Ka's biphasic response to niflumic acid, a drug belonging to the fenamate class, with F256A being potentiated 37-fold and N257A being potently blocked with a KD similar to 1 mu M. These residues are localized in the same extracellular I-J loop which harbors a regulatory Ca2+ binding site. This loop thus can represent an ideal and CLC-K specific target for extracellular ligands able to modulate channel activity. Furthermore, we demonstrated the involvement of the barttin subunit in the NFA potentiation. Indeed the F256A mutation confers onto CLC-K1 a transient potentiation induced by NFA which is found only when CLC-K1/F256A is co-expressed with barttin. Thus, in addition to the role of barttin in targeting and gating, the subunit participates in the pharmacological modulation of CLC-K channels and thus represents a further target for potential drugs. (C) 2014 The Authors. Published by Elsevier B.V.
RivistaBiochimica Et Biophysica Acta. Biomembranes
ISSN0005-2736
Impact factor0
Volume1838
Pagina inizio2745
Pagina fine2756
Autori IBFMichael PUSCH, Giovanni ZIFARELLI, Antonella GRADOGNA
Linee di Ricerca IBFMD.P01.009.001
Sedi IBFIBF.GE