title: Preformed reggie/flotillin caps: stable priming platforms for macrodomain assembly in T cells.
abstract: T cell activation after contact with an antigen-presenting cell depends on the regulated assembly of the T cell receptor signaling complex, which involves the polarized assembly of a stable, raft-like macrodomain surrounding engaged T cell receptors. Here we show that the preformed reggie/flotillin caps present in resting T cells act as priming platforms for macrodomain assembly. Preformed reggie-1/flotillin-2 caps are exceptionally stable, as shown by fluorescence recovery after photobleaching (FRAP). Upon T cell stimulation, signaling molecules are recruited to the stable reggie/flotillin caps. Importantly, a trans-negative reggie-1/flotillin-2 deletion mutant, which interferes with assembly of the preformed reggie/flotillin cap, impairs raft polarization and macrodomain formation after T cell activation. Accordingly, expression of the trans-negative reggie-1 mutant leads to the incorrect positioning of the guanine nucleotide exchange factor Vav, resulting in defects in cytoskeletal reorganization. Thus, the preformed reggie/flotillin caps are stable priming platforms for the assembly of multiprotein complexes controlling actin reorganization during T cell activation.
authors.affiliation: Developmental Neurobiology Group, Department of Biology, University of Konstanz, Konstanz, Germany. matthiaslanghorst@email.de
authors.forename: Matthias F
authors.initials: MF
authors.lastname: Langhorst
authors.forename: Alexander
authors.initials: A
authors.lastname: Reuter
authors.forename: Georg
authors.initials: G
authors.lastname: Luxenhofer
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Boneberg
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Legler
authors.forename: Helmut
authors.initials: H
authors.lastname: Plattner
authors.forename: Claudia A O
authors.initials: CA
authors.lastname: Stuermer
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D003599:Cytoskeleton / Q000378:metabolism; D017353:Gene Deletion; D005786:Gene Expression Regulation; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D021962:Membrane Microdomains / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D016716:PC12 Cells; D051381:Rats; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*
chemical_list: D000199:Actins; D008565:Membrane Proteins; C106354:flotillins