NR ANUS
AU Lorca,R.A.; Chacon,M.A.; Barria,M.I.; Inestrosa,N.C.; Huidobro-Toro,J.P.
TI The human prion octarepeat fragment prevents and reverses the inhibitory action of copper in the P2X4 receptor without modifying the zinc action
QU Journal of Neurochemistry 2003 May; 85(3): 709-16
PT journal article
AB Human prion protein fragments (PrP60-67 or PrP59-91) prevented and reversed the inhibition elicited by 5 micro m copper on the P2X4 receptor expressed in Xenopus laevis oocytes. A 60-s pre-application of 5 micro m copper caused a 69.2 +/- 2.6% inhibition of the 10 micro m adenosine triphosphate (ATP)-evoked currents, an effect that was prevented by mixing 5 micro m copper with 0.01-10 micro m of the PrP fragments 1-min prior to application. This interaction was selective, as PrP59-91 did not alter the facilitatory action of zinc. The EC50 of PrP60-67 and PrP59-91 for the reduction of the copper inhibition were 4.6 +/- 1 and 1.3 +/- 0.4 micro m, respectively. A synthetic PrP59-91 variant in which all four His were replaced by Ala was inactive. However, the replacement of Trp in each of the four putative copper-binding domains by Ala slightly decreased its potency. Furthermore, the application of 10 micro m PrP59-91 reversed the copper-evoked inhibition, restoring the ATP concentration curve to the same level as the non-inhibited state. Fragment 139-157 of betaA4 amyloid precursor protein also prevented the action of copper; its EC50 was 1.6 +/- 0.1 micro m; the metal chelator penicillamine was equipotent with PrP60-67, but carnosine was significantly less potent. Our findings highlight the role of PrP in copper homeostasis and hint at its possible role as a modulator of synapses regulated by this trace metal.
MH Adenosine Triphosphate/pharmacology; Amino Acid Substitution; Amyloid beta-Protein Precursor/pharmacology; Animal; Binding Sites/genetics; Chelating Agents/pharmacology; Copper/*antagonists & inhibitors/pharmacology; Dose-Response Relationship, Drug; Human; Microinjections; Oocytes/drug effects/metabolism; Patch-Clamp Techniques; Peptide Fragments/*pharmacology; *Prions/*pharmacology; Receptors, Purinergic P2/*antagonists & inhibitors/metabolism; Repetitive Sequences, Amino Acid/*physiology; Structure-Activity Relationship; Support, Non-U.S. Gov't; Xenopus laevis; Zinc/*pharmacology
AD Centro de Regulación Celular y Patología, J. V. Luco Instituto MIFAB, Departamentos de Fisiología (Ramón A. Lorca, J. Pablo Huidobro-Toro) y Biología Celular y Molecular (Marcelo Chacón, María Inés Barría, Nibaldo C. Inestrosa), Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
SP englisch
PO England