Inhibition of T cell activation by cyclic adenosine 5'-monophosphate requires lipid raft targeting of protein kinase A type I by the A-kinase anchoring protein ezrin

Anja Ruppelt; Randi Mosenden; Mikaela Grönholm; Einar M Aandahl; Derek Tobin; Cathrine R Carlson; Hilde Abrahamsen; Friedrich W Herberg; Olli Carpén; Kjetil Taskén

doi:10.4049/jimmunol.179.8.5159

Inhibition of T cell activation by cyclic adenosine 5'-monophosphate requires lipid raft targeting of protein kinase A type I by the A-kinase anchoring protein ezrin

J Immunol. 2007 Oct 15;179(8):5159-68. doi: 10.4049/jimmunol.179.8.5159.

Authors

Anja Ruppelt¹, Randi Mosenden, Mikaela Grönholm, Einar M Aandahl, Derek Tobin, Cathrine R Carlson, Hilde Abrahamsen, Friedrich W Herberg, Olli Carpén, Kjetil Taskén

Affiliation

¹ The Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway.

PMID: 17911601
DOI: 10.4049/jimmunol.179.8.5159

Abstract

cAMP negatively regulates T cell immune responses by activation of type I protein kinase A (PKA), which in turn phosphorylates and activates C-terminal Src kinase (Csk) in T cell lipid rafts. Using yeast two-hybrid screening, far-Western blot, immunoprecipitation and immunofluorescense analyses, and small interfering RNA-mediated knockdown, we identified Ezrin as the A-kinase anchoring protein that targets PKA type I to lipid rafts. Furthermore, Ezrin brings PKA in proximity to its downstream substrate Csk in lipid rafts by forming a multiprotein complex consisting of PKA/Ezrin/Ezrin-binding protein 50, Csk, and Csk-binding protein/phosphoprotein associated with glycosphingolipid-enriched microdomains. The complex is initially present in immunological synapses when T cells contact APCs and subsequently exits to the distal pole. Introduction of an anchoring disruptor peptide (Ht31) into T cells competes with Ezrin binding to PKA and thereby releases the cAMP/PKA type I-mediated inhibition of T cell proliferation. Finally, small interfering RNA-mediated knockdown of Ezrin abrogates cAMP regulation of IL-2. We propose that Ezrin is essential in the assembly of the cAMP-mediated regulatory pathway that modulates T cell immune responses.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

A Kinase Anchor Proteins / chemistry
A Kinase Anchor Proteins / metabolism
A Kinase Anchor Proteins / physiology*
Actins / metabolism
Cells, Cultured
Cloning, Molecular
Cyclic AMP / pharmacology*
Cyclic AMP-Dependent Protein Kinase Type I / antagonists & inhibitors
Cyclic AMP-Dependent Protein Kinase Type I / genetics
Cyclic AMP-Dependent Protein Kinase Type I / metabolism*
Cytoskeletal Proteins / antagonists & inhibitors
Cytoskeletal Proteins / genetics
Cytoskeletal Proteins / physiology*
Cytoskeleton / immunology
Cytoskeleton / metabolism
Humans
Immunosuppressive Agents / pharmacology*
Jurkat Cells
Membrane Microdomains / metabolism
Membrane Microdomains / physiology*
Peptide Mapping
Phosphoproteins / physiology
Protein Binding
RNA, Small Interfering / pharmacology
Receptor-CD3 Complex, Antigen, T-Cell / metabolism
Signal Transduction / immunology
Sodium-Hydrogen Exchangers / physiology
T-Lymphocytes / enzymology
T-Lymphocytes / immunology*
T-Lymphocytes / metabolism*

Substances

A Kinase Anchor Proteins
Actins
Cytoskeletal Proteins
Immunosuppressive Agents
Phosphoproteins
RNA, Small Interfering
Receptor-CD3 Complex, Antigen, T-Cell
Sodium-Hydrogen Exchangers
ezrin
sodium-hydrogen exchanger regulatory factor
Cyclic AMP
Cyclic AMP-Dependent Protein Kinase Type I