title: The inhibition of functional expression of calcium channels by prion protein demonstrates competition with α2δ for GPI-anchoring pathways.
abstract: It has been shown recently that PrP (prion protein) and the calcium channel auxiliary α2δ 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/β and α2δ-1 or α2δ-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 α2δ 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 α2δ-1 construct, α2δ-1ΔC, 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/β currents formed with α2δ-1ΔC, rather than α2δ-1. It is possible that PrP and α2δ-1 compete for GPI-anchor intermediates or trafficking pathways, or that interaction between PrP and α2δ-1 requires association in cholesterol-rich membrane microdomains. Our additional finding that CaV2.1/β1b/α2δ-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 α2δ subunit function.
authors: *Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, U.K.
authors: Anita
authors: A
authors: Alvarez-Laviada
authors: *Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, U.K.
authors: Ivan
authors: I
authors: Kadurin
authors: *Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, U.K.
authors: Assunta
authors: A
authors: Senatore
authors: †Dulbecco Telethon Institute c/o Department of Neuroscience, IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri", Milano, Italy.
authors: Roberto
authors: R
authors: Chiesa
authors: *Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, U.K.
authors: Annette C
authors: AC
authors: Dolphin
mesh_terms: D000818:Animals; D001667:Binding, Competitive / Q000235:genetics; D015220:Calcium Channels / Q000378:metabolism*; D020864:Calcium Channels, N-Type / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011328:Prions / Q000096:biosynthesis*; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000235:genetics; D051381:Rats; D015398:Signal Transduction / Q000235:genetics; D014981:Xenopus
chemical_list: D015220:Calcium Channels; D020864:Calcium Channels, N-Type; D017261:Glycosylphosphatidylinositols; D011328:Prions; C512066:CACNA2D1 protein, mouse