RT Journal Article
A1 Lysechko, Tara L.
A1 Ostergaard, Hanne L.
T1 Differential Src Family Kinase Activity Requirements for CD3ζ Phosphorylation/ZAP70 Recruitment and CD3ε Phosphorylation1
JF The Journal of Immunology
JO J Immunol
YR 2005
DO 10.4049/jimmunol.174.12.7807
VO 174
IS 12
SP 7807
OP 7814
SN 0022-1767
AB The current model of T cell activation is that TCR engagement stimulates Src family tyrosine kinases (SFK) to phosphorylate CD3ζ. CD3ζ phosphorylation allows for the recruitment of the tyrosine kinase ZAP70, which is phosphorylated and activated by SFK, leading to the phosphorylation of downstream targets. We stimulated mouse CTLs with plate-bound anti-CD3 and, after cell lysis, recovered proteins that associated with the CD3 complex. The protein complexes were not preformed, and a number of tyrosine-phosphorylated proteins were inducibly and specifically associated with the TCR/CD3 complex. These results suggest that complex formation only occurs at the site of TCR engagement. The recruitment and tyrosine phosphorylation of most proteins were abolished when T cells were stimulated in the presence of the SFK inhibitor PP2. Surprisingly, CD3ζ, but not CD3ε, was inducibly tyrosine phosphorylated in the presence of PP2. Furthermore, ZAP70 was recruited, but not phosphorylated, after TCR stimulation in the presence of PP2, thus confirming the phosphorylation status of CD3ζ. These data suggest that there is a differential requirement for SFK activity in phosphorylation of CD3ζ vs CD3ε. Consistent with this possibility, ZAP70 recruitment was also detected with anti-CD3-stimulated, Lck-deficient human Jurkat T cells. We conclude that TCR/CD3-induced CD3ζ phosphorylation and ZAP70 recruitment do not absolutely require Lck or other PP2-inhibitable SFK activity, but that SFK activity is absolutely required for CD3ε and ZAP70 phosphorylation. These data reveal the potential for regulation of signaling through the TCR complex by the differential recruitment or activation of SFK.
RD 4/19/2024
UL https://doi.org/10.4049/jimmunol.174.12.7807