The inhibition of functional expression of calcium channels by prion protein demonstrates competition with ?2? for GPI-anchoring pathways.

ABSTRACT: It has been shown recently that PrP (prion protein) and the calcium channel auxiliary ?2? subunits interact in neurons and expression systems [Senatore, Colleoni, Verderio, Restelli, Morini, Condliffe, Bertani, Mantovani, Canovi, Micotti, Forloni, Dolphin, Matteoli, Gobbi and Chiesa (2012) Neuron 74, 300-313]. In the present study we examined whether there was an effect of PrP on calcium currents. We have shown that when PrP is co-expressed with calcium channels formed from CaV2.1/? and ?2?-1 or ?2?-2, there is a consistent decrease in calcium current density. This reduction was absent when a PrP construct was used lacking its GPI (glycosylphosphatidylinositol) anchor. We have reported previously that ?2? subunits are able to form GPI-anchored proteins [Davies, Kadurin, Alvarez-Laviada, Douglas, Nieto-Rostro, Bauer, Pratt and Dolphin (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 1654-1659] and show further evidence in the present paper. We have characterized recently a C-terminally truncated ?2?-1 construct, ?2?-1?C, and found that, despite loss of its membrane anchor, it still shows a partial ability to increase calcium currents [Kadurin, Alvarez-Laviada, Ng, Walker-Gray, D'Arco, Fadel, Pratt and Dolphin (2012) J. Biol. Chem. 1287, 33554-33566]. We now find that PrP does not inhibit CaV2.1/? currents formed with ?2?-1?C, rather than ?2?-1. It is possible that PrP and ?2?-1 compete for GPI-anchor intermediates or trafficking pathways, or that interaction between PrP and ?2?-1 requires association in cholesterol-rich membrane microdomains. Our additional finding that CaV2.1/?1b/?2?-1 currents were inhibited by GPI-GFP, but not cytosolic GFP, indicates that competition for limited GPI-anchor intermediates or trafficking pathways may be involved in PrP suppression of ?2? subunit function.

SUBMITTER: Alvarez-Laviada A 

PROVIDER: S-EPMC3924758 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature