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The transmembrane adaptor protein TRIM regulates T cell receptor (TCR) expression and TCR-mediated signaling via an association with the TCR zeta chain.

Kirchgessner H, Dietrich J, Scherer J, Isomäki P, Korinek V, Hilgert I, Bruyns E, Leo A, Cope AP, Schraven B - J. Exp. Med. (2001)

Bottom Line: T cell receptor (TCR)-interacting molecule (TRIM) is a recently identified transmembrane adaptor protein, which is exclusively expressed in T cells.Here we demonstrate that in mature T cells, TRIM preferentially interacts with the TCR via the TCR-zeta chains and to a lesser extent via the CD3-straightepsilon/gamma heterodimer.Collectively, our data identify TRIM as a novel integral component of the TCR complex and suggest that one function of TRIM might be to modulate the strength of signals transduced through the TCR through regulation of TCR expression on the cell surface.

View Article: PubMed Central - PubMed

Affiliation: Institute for Immunology, Ruprecht-Karls University Heidelberg, D-69120 Heidelberg, Germany.

ABSTRACT
T cell receptor (TCR)-interacting molecule (TRIM) is a recently identified transmembrane adaptor protein, which is exclusively expressed in T cells. Here we demonstrate that in mature T cells, TRIM preferentially interacts with the TCR via the TCR-zeta chains and to a lesser extent via the CD3-straightepsilon/gamma heterodimer. Transient or stable overexpression of TRIM in Jurkat T cells results in enhancement of TCR expression on the cell surface and elevated induction of Ca(2+) mobilization after T cell activation. TRIM-mediated upregulation of TCR expression results from inhibition of spontaneous TCR internalization and stabilization of TCR complexes on the cell surface. Collectively, our data identify TRIM as a novel integral component of the TCR complex and suggest that one function of TRIM might be to modulate the strength of signals transduced through the TCR through regulation of TCR expression on the cell surface.

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Inhibition of spontaneous TCR internalization by TRIM. (A) Vector transfectants or TRIM transfectants were treated for 90 min with BFA at 37°C. Subsequently, the expression of the TCR-α/β heterodimer was determined by indirect immunofluorescence. ctrl., control. (B and C) Vector transfectants or TRIM transfectants were externally labeled on ice with PE-labeled CD3ε mAb UCHT-1. After washing the temperature was shifted to 37°C for the indicated periods of time. After incubation at 37°C, the temperature was again lowered to 4°C and cells were externally labeled with the anti-TCR mAb C305 (IgM) followed by FITC-labeled goat anti–mouse IgM serum. Cells were then analyzed by flow cytometry (B) or by confocal laserscanning analysis (C). sTCR, surface TCR. (D) TCR internalization is only downregulated in Jurkat T cells overexpressing TRIM. Jurkat T cells transfected with a plasmid encoding TRIM were labeled on ice with UCHT1-PE as described above. After washing, cells were either incubated on ice (left) or incubated for 15 min at 37°C (right). Cells were then permeabilized and stained with biotinylated TRIM-4 mAb followed by detection using streptavidin Cy2.
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Figure 4: Inhibition of spontaneous TCR internalization by TRIM. (A) Vector transfectants or TRIM transfectants were treated for 90 min with BFA at 37°C. Subsequently, the expression of the TCR-α/β heterodimer was determined by indirect immunofluorescence. ctrl., control. (B and C) Vector transfectants or TRIM transfectants were externally labeled on ice with PE-labeled CD3ε mAb UCHT-1. After washing the temperature was shifted to 37°C for the indicated periods of time. After incubation at 37°C, the temperature was again lowered to 4°C and cells were externally labeled with the anti-TCR mAb C305 (IgM) followed by FITC-labeled goat anti–mouse IgM serum. Cells were then analyzed by flow cytometry (B) or by confocal laserscanning analysis (C). sTCR, surface TCR. (D) TCR internalization is only downregulated in Jurkat T cells overexpressing TRIM. Jurkat T cells transfected with a plasmid encoding TRIM were labeled on ice with UCHT1-PE as described above. After washing, cells were either incubated on ice (left) or incubated for 15 min at 37°C (right). Cells were then permeabilized and stained with biotinylated TRIM-4 mAb followed by detection using streptavidin Cy2.

Mentions: As reported previously 28, BFA treatment of vector-transfected Jurkat T cells induced only an ∼20% downregulation of TCR expression (Fig. 4 A). This contrasts the situation in T cell hybridomas in which BFA treatment has been reported most recently to induce a much stronger downregulation of TCR expression 29. Nevertheless, in Jurkat T cells overexpressing TRIM, BFA had almost completely lost its capability to induce downregulation of TCR expression. This suggests that the higher levels of TCR expression in Jurkat T cells overexpressing TRIM likely result from TRIM-mediated inhibition of spontaneous TCR internalization rather than from facilitating transport of newly synthesized receptors to the cell surface.


The transmembrane adaptor protein TRIM regulates T cell receptor (TCR) expression and TCR-mediated signaling via an association with the TCR zeta chain.

Kirchgessner H, Dietrich J, Scherer J, Isomäki P, Korinek V, Hilgert I, Bruyns E, Leo A, Cope AP, Schraven B - J. Exp. Med. (2001)

Inhibition of spontaneous TCR internalization by TRIM. (A) Vector transfectants or TRIM transfectants were treated for 90 min with BFA at 37°C. Subsequently, the expression of the TCR-α/β heterodimer was determined by indirect immunofluorescence. ctrl., control. (B and C) Vector transfectants or TRIM transfectants were externally labeled on ice with PE-labeled CD3ε mAb UCHT-1. After washing the temperature was shifted to 37°C for the indicated periods of time. After incubation at 37°C, the temperature was again lowered to 4°C and cells were externally labeled with the anti-TCR mAb C305 (IgM) followed by FITC-labeled goat anti–mouse IgM serum. Cells were then analyzed by flow cytometry (B) or by confocal laserscanning analysis (C). sTCR, surface TCR. (D) TCR internalization is only downregulated in Jurkat T cells overexpressing TRIM. Jurkat T cells transfected with a plasmid encoding TRIM were labeled on ice with UCHT1-PE as described above. After washing, cells were either incubated on ice (left) or incubated for 15 min at 37°C (right). Cells were then permeabilized and stained with biotinylated TRIM-4 mAb followed by detection using streptavidin Cy2.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2193385&req=5

Figure 4: Inhibition of spontaneous TCR internalization by TRIM. (A) Vector transfectants or TRIM transfectants were treated for 90 min with BFA at 37°C. Subsequently, the expression of the TCR-α/β heterodimer was determined by indirect immunofluorescence. ctrl., control. (B and C) Vector transfectants or TRIM transfectants were externally labeled on ice with PE-labeled CD3ε mAb UCHT-1. After washing the temperature was shifted to 37°C for the indicated periods of time. After incubation at 37°C, the temperature was again lowered to 4°C and cells were externally labeled with the anti-TCR mAb C305 (IgM) followed by FITC-labeled goat anti–mouse IgM serum. Cells were then analyzed by flow cytometry (B) or by confocal laserscanning analysis (C). sTCR, surface TCR. (D) TCR internalization is only downregulated in Jurkat T cells overexpressing TRIM. Jurkat T cells transfected with a plasmid encoding TRIM were labeled on ice with UCHT1-PE as described above. After washing, cells were either incubated on ice (left) or incubated for 15 min at 37°C (right). Cells were then permeabilized and stained with biotinylated TRIM-4 mAb followed by detection using streptavidin Cy2.
Mentions: As reported previously 28, BFA treatment of vector-transfected Jurkat T cells induced only an ∼20% downregulation of TCR expression (Fig. 4 A). This contrasts the situation in T cell hybridomas in which BFA treatment has been reported most recently to induce a much stronger downregulation of TCR expression 29. Nevertheless, in Jurkat T cells overexpressing TRIM, BFA had almost completely lost its capability to induce downregulation of TCR expression. This suggests that the higher levels of TCR expression in Jurkat T cells overexpressing TRIM likely result from TRIM-mediated inhibition of spontaneous TCR internalization rather than from facilitating transport of newly synthesized receptors to the cell surface.

Bottom Line: T cell receptor (TCR)-interacting molecule (TRIM) is a recently identified transmembrane adaptor protein, which is exclusively expressed in T cells.Here we demonstrate that in mature T cells, TRIM preferentially interacts with the TCR via the TCR-zeta chains and to a lesser extent via the CD3-straightepsilon/gamma heterodimer.Collectively, our data identify TRIM as a novel integral component of the TCR complex and suggest that one function of TRIM might be to modulate the strength of signals transduced through the TCR through regulation of TCR expression on the cell surface.

View Article: PubMed Central - PubMed

Affiliation: Institute for Immunology, Ruprecht-Karls University Heidelberg, D-69120 Heidelberg, Germany.

ABSTRACT
T cell receptor (TCR)-interacting molecule (TRIM) is a recently identified transmembrane adaptor protein, which is exclusively expressed in T cells. Here we demonstrate that in mature T cells, TRIM preferentially interacts with the TCR via the TCR-zeta chains and to a lesser extent via the CD3-straightepsilon/gamma heterodimer. Transient or stable overexpression of TRIM in Jurkat T cells results in enhancement of TCR expression on the cell surface and elevated induction of Ca(2+) mobilization after T cell activation. TRIM-mediated upregulation of TCR expression results from inhibition of spontaneous TCR internalization and stabilization of TCR complexes on the cell surface. Collectively, our data identify TRIM as a novel integral component of the TCR complex and suggest that one function of TRIM might be to modulate the strength of signals transduced through the TCR through regulation of TCR expression on the cell surface.

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