Requirement for Daxx in mature T-cell proliferation and activation

Leal-Sanchez J, Couzinet A, Rossin A, Abdel-Sater F, Chakrabandhu K, Luci C, Anjuere F, Stebe E, Hancock D, Hueber AO
Source: Cell Death Differ
Publication Date: (2007)
Issue: 14(4): 795-806
Research Area:
Immunotherapy / Hematology
Cells used in publication:
Species: human
Tissue Origin: blood
Nucleofectorâ„¢ I/II/2b
The protein Daxx promotes Fas-mediated cell death through activation of apoptosis signal-regulating kinase 1, leading to the activation of the MAPKs JNK and p38. Owing to the in utero lethality of daxx-deficient mice, the in vivo role of Daxx has been so far difficult to analyze. We have generated transgenic mice expressing a dominant-negative form of Daxx (Daxx-DN) in the T-cell lineage. We show that Daxx is recruited to the Fas receptor upon FasL engagement and that Daxx-DN expression protects activated T cells from Fas-induced cell death, by preventing the death-inducing signal complex to be properly formed. Normal lymphocyte development and homeostasis are nevertheless observed. Interestingly, we report that both in vitro and in vivo stimulation of Daxx-DN T-lymphocytes leads to increased proliferative T-cell responses. This increased proliferation is associated with a marked increase in tyrosine phosphorylation of LAT and ZAP70 as Daxx-DN favor their recruitment to the T-cell receptor (TCR) complex. These findings identify Daxx as a critical regulator of T-lymphocyte homeostasis by decreasing TCR-induced cell proliferation and by promoting Fas-mediated cell death.