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Cytotoxic T lymphocyte antigen 4 (CTLA-4) interferes with extracellular signal-regulated kinase (ERK) and Jun NH2-terminal kinase (JNK) activation, but does not affect phosphorylation of T cell receptor zeta and ZAP70.

Calvo CR, Amsen D, Kruisbeek AM - J. Exp. Med. (1997)

Bottom Line: We here report that CTLA-4 engagement strikingly selectively shuts off activation of downstream T cell receptor (TCR)/CD28 signaling events, i.e., activation of the microtubule-associated protein kinase (MAPKs) ERK and JNK.In sharp contrast, proximal TCR signaling events such as ZAP70 and TCR-zeta chain phosphorylation are not affected by CTLA-4 engagement on activated T cells.Since activation of the ERK and JNK kinases is required for stimulation of interleukin (IL)-2 transcription, these data provide a molecular explanation for the block in IL-2 production imposed by CTLA-4.

View Article: PubMed Central - PubMed

Affiliation: Division of Immunology, The Netherlands Cancer Institute, Amsterdam.

ABSTRACT
Cytotoxic T lymphocyte antigen 4 (CTLA-4) is an important regulator of T cell homeostasis. Ligation of this receptor leads to prominent downregulation of T cell proliferation, mainly as a consequence of interference with IL-2 production. We here report that CTLA-4 engagement strikingly selectively shuts off activation of downstream T cell receptor (TCR)/CD28 signaling events, i.e., activation of the microtubule-associated protein kinase (MAPKs) ERK and JNK. In sharp contrast, proximal TCR signaling events such as ZAP70 and TCR-zeta chain phosphorylation are not affected by CTLA-4 engagement on activated T cells. Since activation of the ERK and JNK kinases is required for stimulation of interleukin (IL)-2 transcription, these data provide a molecular explanation for the block in IL-2 production imposed by CTLA-4.

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Combined triggering of CD3 and CD28 delays  downregulation of ERK2 activity by CTLA-4. Preactivated T  cells were coated with different  combinations of antibodies as in  Fig. 1 and lysed 1, 5, or 10 min  after addition of warm cross-linking antibody. ERK2 was immunoprecipitated and in vitro  kinase reactions were performed  (top). The same lysates were  tested for ERK2 protein abundance (middle). ERK2 activities  were quantified using a phosphorimager and represented as  relative values compared to  ERK2 activities from unstimulated cells (unstimulated = 1;  bottom).
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Figure 2: Combined triggering of CD3 and CD28 delays downregulation of ERK2 activity by CTLA-4. Preactivated T cells were coated with different combinations of antibodies as in Fig. 1 and lysed 1, 5, or 10 min after addition of warm cross-linking antibody. ERK2 was immunoprecipitated and in vitro kinase reactions were performed (top). The same lysates were tested for ERK2 protein abundance (middle). ERK2 activities were quantified using a phosphorimager and represented as relative values compared to ERK2 activities from unstimulated cells (unstimulated = 1; bottom).

Mentions: In contrast to earlier published results that suggest that ERK2 activity is not affected by CD28 triggering (20, 27), we consistently found that in cells stimulated with anti-CD3 and anti-CD28, ERK2 activity is somewhat higher (Fig. 1). Moreover, we found that ERK2 activity induced in the presence of anti-CD28 usually persisted longer than ERK2 activity induced by TCR triggering alone, reaching its peak by 10 min after activation (Fig. 2). Interestingly, an effect of CD28 signaling on ERK2 activity is also revealed by the finding that 1 min after stimulation the inhibition of ERK2 activity/activation by CTLA-4 is prevented by anti-CD28 (compare Figs. 1 A and 2). At later time points, however, anti-CD3– and anti-CD28–induced ERK2 activity is also downregulated by CTLA-4 (Fig. 2) with almost complete inhibition at 10 min. Together, these results demonstrate that CTLA-4 on preactivated T cells downregulates TCR-induced ERK2 activity, either by interfering with activation of this kinase or by directly modulating ERK2 kinase activity.


Cytotoxic T lymphocyte antigen 4 (CTLA-4) interferes with extracellular signal-regulated kinase (ERK) and Jun NH2-terminal kinase (JNK) activation, but does not affect phosphorylation of T cell receptor zeta and ZAP70.

Calvo CR, Amsen D, Kruisbeek AM - J. Exp. Med. (1997)

Combined triggering of CD3 and CD28 delays  downregulation of ERK2 activity by CTLA-4. Preactivated T  cells were coated with different  combinations of antibodies as in  Fig. 1 and lysed 1, 5, or 10 min  after addition of warm cross-linking antibody. ERK2 was immunoprecipitated and in vitro  kinase reactions were performed  (top). The same lysates were  tested for ERK2 protein abundance (middle). ERK2 activities  were quantified using a phosphorimager and represented as  relative values compared to  ERK2 activities from unstimulated cells (unstimulated = 1;  bottom).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199134&req=5

Figure 2: Combined triggering of CD3 and CD28 delays downregulation of ERK2 activity by CTLA-4. Preactivated T cells were coated with different combinations of antibodies as in Fig. 1 and lysed 1, 5, or 10 min after addition of warm cross-linking antibody. ERK2 was immunoprecipitated and in vitro kinase reactions were performed (top). The same lysates were tested for ERK2 protein abundance (middle). ERK2 activities were quantified using a phosphorimager and represented as relative values compared to ERK2 activities from unstimulated cells (unstimulated = 1; bottom).
Mentions: In contrast to earlier published results that suggest that ERK2 activity is not affected by CD28 triggering (20, 27), we consistently found that in cells stimulated with anti-CD3 and anti-CD28, ERK2 activity is somewhat higher (Fig. 1). Moreover, we found that ERK2 activity induced in the presence of anti-CD28 usually persisted longer than ERK2 activity induced by TCR triggering alone, reaching its peak by 10 min after activation (Fig. 2). Interestingly, an effect of CD28 signaling on ERK2 activity is also revealed by the finding that 1 min after stimulation the inhibition of ERK2 activity/activation by CTLA-4 is prevented by anti-CD28 (compare Figs. 1 A and 2). At later time points, however, anti-CD3– and anti-CD28–induced ERK2 activity is also downregulated by CTLA-4 (Fig. 2) with almost complete inhibition at 10 min. Together, these results demonstrate that CTLA-4 on preactivated T cells downregulates TCR-induced ERK2 activity, either by interfering with activation of this kinase or by directly modulating ERK2 kinase activity.

Bottom Line: We here report that CTLA-4 engagement strikingly selectively shuts off activation of downstream T cell receptor (TCR)/CD28 signaling events, i.e., activation of the microtubule-associated protein kinase (MAPKs) ERK and JNK.In sharp contrast, proximal TCR signaling events such as ZAP70 and TCR-zeta chain phosphorylation are not affected by CTLA-4 engagement on activated T cells.Since activation of the ERK and JNK kinases is required for stimulation of interleukin (IL)-2 transcription, these data provide a molecular explanation for the block in IL-2 production imposed by CTLA-4.

View Article: PubMed Central - PubMed

Affiliation: Division of Immunology, The Netherlands Cancer Institute, Amsterdam.

ABSTRACT
Cytotoxic T lymphocyte antigen 4 (CTLA-4) is an important regulator of T cell homeostasis. Ligation of this receptor leads to prominent downregulation of T cell proliferation, mainly as a consequence of interference with IL-2 production. We here report that CTLA-4 engagement strikingly selectively shuts off activation of downstream T cell receptor (TCR)/CD28 signaling events, i.e., activation of the microtubule-associated protein kinase (MAPKs) ERK and JNK. In sharp contrast, proximal TCR signaling events such as ZAP70 and TCR-zeta chain phosphorylation are not affected by CTLA-4 engagement on activated T cells. Since activation of the ERK and JNK kinases is required for stimulation of interleukin (IL)-2 transcription, these data provide a molecular explanation for the block in IL-2 production imposed by CTLA-4.

Show MeSH