Distinct T cell developmental consequences in humans and mice expressing identical mutations in the DLAARN motif of ZAP-70.
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Elder ME, Skoda-Smith S, Kadlecek TA, Wang F, Wu J, Weiss A
Distinct T cell developmental consequences in humans and mice expressing identical mutations in the DLAARN motif of ZAP-70.
J Immunol. 2001 Jan 1;166(1):656-61.
- PubMed ID
- 11123350 [ View in PubMed]
- Abstract
The protein tyrosine kinase, ZAP-70, is pivotally involved in transduction of Ag-binding signals from the TCR required for T cell activation and development. Defects in ZAP-70 result in SCID in humans and mice. We describe an infant with SCID due to a novel ZAP-70 mutation, comparable with that which arose spontaneously in an inbred mouse colony. The patient inherited a homozygous missense mutation within the highly conserved DLAARN motif in the ZAP-70 kinase domain. Although the mutation only modestly affected protein stability, catalytic function was absent. Despite identical changes in the amino acid sequence of ZAP-70, the peripheral T cell phenotypes of our patient and affected mice are distinct. ZAP-70 deficiency in this patient, as in other humans, is characterized by abundant nonfunctional CD4(+) T cells and absent CD8(+) T cells. In contrast, ZAP-70-deficient mice lack both major T cell subsets. Although levels of the ZAP-70-related protein tyrosine kinase, Syk, may be sufficiently increased in human thymocytes to rescue CD4 development, survival of ZAP-70-deficient T cells in the periphery does not appear to be dependent on persistent up-regulation of Syk expression.