ERM-dependent movement of CD43 defines a novel protein complex distal to the immunological synapse

E J Allenspach1, P Cullinan, J Tong

  • 1Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.

Immunity
|December 1, 2001
PubMed

Insights

The large mucin CD43 moves away from T cell interaction sites, organized by ERM proteins. This movement is crucial for T cell activation, impacting cytokine production like IL-2 and IFN-gamma.

Area of Science:

  • Immunology
  • Cell Biology
  • Cytoskeletal Dynamics

Background:

  • CD43 (leukosialin) is a large mucin expressed on T cells.
  • Immune cell interactions involve dynamic protein organization at the cell surface.
  • The role of CD43 localization in T cell activation is not fully understood.

Purpose of the Study:

  • To investigate the mechanism of CD43 exclusion from the T cell/APC immunological synapse.
  • To determine the role of ERM proteins in CD43 localization and T cell activation.

Main Methods:

  • Immunofluorescence microscopy to track CD43 and ERM protein localization.
  • Expression of dominant-negative ERM mutants in T cells.
  • Measurement of cytokine production (IL-2, IFN-gamma) and cell surface marker upregulation (CD69).

Main Results:

  • CD43 actively accumulates in a membrane domain distal to the T cell receptor engagement site.
  • The cytoplasmic tail of CD43 is essential for this distal localization.
  • ERM proteins colocalize with CD43 and are required for its distal accumulation.
  • Inhibition of ERM function impairs IL-2 and IFN-gamma production but not CD69 upregulation or PKC(theta) focusing.

Conclusions:

  • ERM proteins organize a protein complex distal to the immunological synapse.
  • The exclusion of CD43 from the synapse, mediated by ERM proteins, is important for full T cell activation.
  • This suggests that removing inhibitory proteins from the immunological synapse is a key aspect of T cell activation.

Related Concept Videos

Contact-dependent Signaling01:19

Contact-dependent Signaling

Contact-dependent signaling, as the name suggests, requires that communicating cells be in direct contact with each other. This is achieved either through receptor-ligand interactions or by specialized cytoplasmic channels that allow the flow of small molecules between cells. In animal cells, channels called gap junctions facilitate contact-dependent signaling in certain tissues, whereas, plasmodesmata perform a similar function in plants.
Gap Junctions
In animal cells, gap junctions are formed...
Protein Translocation Machinery on the ER Membrane01:28

Protein Translocation Machinery on the ER Membrane

The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Assembly of Signaling Complexes01:30

Assembly of Signaling Complexes

Multiprotein signaling complexes are formed in a dynamic process involving protein-protein interactions at the cytoplasmic domain of transmembrane receptors or enzymatic and non-enzymatic proteins associated with the receptor. These complexes ensure the activation and propagation of intracellular signals that regulate cell functions.
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
Selectins01:25

Selectins

Cell adhesion is  an essential aspect of multicellularity. While stable cell interactions usually occur between cells of the same type, transient cell interactions occur between cells of different tissue types, such as between neutrophils and endothelial cells. Selectins are one class of cell adhesion molecules (CAMs) that bind carbohydrate ligands to form transient cell adhesion. They are rod-like proteins with a long extracellular part of variable length ending with the lectin domain, which...
Immunoglobulin-like Cell Adhesion Molecules01:31

Immunoglobulin-like Cell Adhesion Molecules

Immunoglobulin-like cell adhesion molecules or Ig-CAMs are a versatile group of cell surface glycoproteins belonging to the immunoglobulin protein superfamily. Ig-CAMs possess the characteristic immunoglobulin protein domains and other domains such as the fibronectin type III domain. The Ig domains are glycosylated to varying degrees in different Ig-CAMs.
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...
T Cell Activation and Clonal Selection01:22

T Cell Activation and Clonal Selection

T cells are integral to our adaptive immune system, recognizing and effectively responding to foreign antigens. T cell activation and clonal selection are pivotal in orchestrating this immune response. This article elucidates these mechanisms, detailing the roles of cluster of differentiation (CD) markers, major histocompatibility complex (MHC) molecules, costimulatory signals, and the process of clonal selection.
Naive T cells that have not yet encountered an antigen express two primary CD...