NR ARDB
AU Stuermer,C.A.O.; Langhorst,M.F.; Wiechers,M.F.; Legler,D.; Hannbeck,S.; Guse,A.H.; Plattner,H.
TI PrPc capping in T cells promotes its association with the lipid raft proteins reggie-1 and reggie-2 and leads to signal transduction
QU TSE-Forum, 4. Kongress - Nationale TSE-Forschungsplattform, Düsseldorf 28.10.-29.10.2004, Vortrag V-18
PT Konferenz-Vortrag
AB
The cellular prion protein (PrPc) is a GPI-anchored protein in neurons and lymphocytes which resides in lipid rafts. We are interested in the physiological function of PrPc and the type of raft PrPc employs for signaling across the plasma membrane. Lymphocytes and neurons express the non-caveolar lipid raft proteins reggie-1 and reggie-2 in distinct patterns which manifests itself as preformed cap in T lymphocytes. The reggies apparently associate into oligomeric structures and scaffolds that promote the focal assembly of interacting proteins and signal transduction. We have analyzed if PrPc cross-linking in T cells leads to capping of PrPc, and more specifically, to the association of PrPc with the preformed reggie caps and signal transduction.
Here, we report that AB-mediated PrPc cross-linking in Jurkat T cells and peripheral blood T lymphocytes leads to capping of PrPc and its association with the reggies. We demonstrate further that cross-linked PrPc coclusters with Thy-1, TCR/CD3 complex, fyn, lck, and LAT (linker of activated T cells) in the cap region where an increase of tyrosine phosphorylation and actin polymerization is indicative of signal transduction. This is substantiated by our results showing a brief elevation of [Ca2+]i in response to PrPc cross-linking, and increased phosphorylation of the MAP kinases ERK 1/2 (extracellular regulated kinases 1/2). Moreover, suppression of the increase in [Ca2+]i by a membrane permeable Ca2+ chelator interferes with PrPc capping. Thus, PrPc capping induces the reorganization of actin and the recruitment of raft-associated signaling molecules. Moreover, PrPc association with reggie rafts triggers distinct transmembrane signal transduction events in T cells that promote the focal concentration of PrPc itself by guiding activated PrPc into preformed reggie caps and then to the recruitment of important interacting signaling molecules as well as TCR/CD3 to the cap. Furthermore, cross-linked PrPc and the reggies are incorporated together in globular intracellular structures, including limp-2 positive late endosomes/lysosomes showing the close association of PrPc and reggie at the plasma membrane and during internal trafficking.
Supported by the TSE program, MWK, Baden-Württemberg, and TR SFB 11 (DFG)
AD C.A.O. Stuermer, M. Langhorst, M. Wiechers, D. Legler; S. Hannbeck, A. Guse* and H. Plattner, Department of Biology, University of Konstanz, 78457 Konstanz; *UKE, Hamburg, Germany
SP englisch
PO Deutschland
OR Tagungsband