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
Impact factor0
Pagina inizio2745
Pagina fine2756
Autori IBFMichael PUSCH, Giovanni ZIFARELLI, Antonella GRADOGNA
Linee di Ricerca IBFMD.P01.009.001