Artículo de revista
Putative ClC-2 chloride channel mediates inward rectification in Drosophila retinal photoreceptors
Fecha
2005-10Autor
Ugarte, G.
Delgado Arriagada, Ricardo
O'Day, P.M.
Farjah, F.
Cid, L. P.
Vergara Montecinos, Cecilia
Bacigalupo Vicuña, Juan
Institución
Resumen
We report that Drosohhila retinal photoreceptors express inwardly rectifying chloride channels that seem to be orthologous to mammalian CIC-2 inward rectifier channels. We measured inwardly rectifying Cl- currents in photoreceptor plasma membranes: Hyperpolarization under whole-cell tight-seal voltage clamp induced inward Cl- currents; and hyperpolarization of voltage-clamped inside-out patches excised from plasma membrane induced CI- currents that have a unitary channel conductance of similar to 3.7 pS. The channel was inhibited by 1 mM Zn2+ and by 1 mM 9-anthracene, but was insensitive to DIDS. Its anion permeability sequence is Cl- = SCN- > Br- > > I-, characteristic of CIC-2 channels. Exogenous polyunsaturated fatty acid, linolenic acid, enhanced or activated the inward rectifier Cl- currents in both whole-cell and excised patch-clamp recordings. Using RT-PCR, we found expression in Drosophila retina of a CIC-2 gene orthologous to mammalian CIC-2 channels. Antibodies to rat CIC-2 channels labeled Drosophila photoreceptor plasma membranes and synaptic regions. Our results provide evidence that the inward rectification in Drosophila retinal photoreceptors is mediated by CIC-2-like channels in the non-transducing (extra-rhabdomeral) plasma membrane, and that this inward rectification can be modulated by polyunsatturated fatty acid.