TCR-induced T cell activation leads to simultaneous phosphorylation at Y505 and Y394 of p56(lck) residues.
Cytometry A
; 81(9): 797-805, 2012 Sep.
Article
en En
| MEDLINE
| ID: mdl-22674786
ABSTRACT
Biochemical studies have demonstrated that phosphorylation of lymphocyte cell kinase (p56(lck) ) is crucial for activation of signaling cascades following T cell receptor (TCR) stimulation. However, whether phosphorylation/dephosphorylation of the activating or inhibitory tyrosine residues occurs upon activation is controversial. Recent advances in intracellular staining of phospho-epitopes and cytometric analysis, requiring few cells, have opened up novel avenues for the field of immunological signaling. Here, we assessed p56(lck) phosphorylation, using a multiparameter flow-cytometric based detection method following T cell stimulation. Fixation and permeabilization in conjunction with zenon labeling technology and/or fluorescently labeled antibodies against total p56(lck) or cognate phospho-tyrosine (pY) residues or surface receptors were used for detection purposes. Our observations showed that activation of Jurkat or primary human T cells using H(2) O(2) or TCR-induced stimulation led to simultaneous phosphorylation of the activating tyrosine residue, Y394 and the inhibitory tyrosine residue, Y505 of p56(lck) . This was followed by downstream calcium flux and expression of T cell activation markers; CD69 and CD40 ligand (CD40L). However, the extent of measurable activation readouts depended on the optimal stimulatory conditions (temperature and/or stimuli combinations). Treatment of cells with a p56(lck) -specific inhibitor, PP2, abolished phosphorylation at either residue in a dose-dependent manner. Taken together, these observations show that TCR-induced stimulation of T cells led to simultaneous phosphorylation of p56(lck) residues. This implies that dephosphorylation of Y505 is not crucial for p56(lck) activity. Also, it is clear that cytometric analysis provides for a rapid, sensitive, and quantitative method to supplement biochemical studies on p56(lck) signaling pathways in T cells at single cell level.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Tirosina
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Receptores de Antígenos de Linfocitos T
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Linfocitos T CD4-Positivos
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Procesamiento Proteico-Postraduccional
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Proteína Tirosina Quinasa p56(lck) Específica de Linfocito
Límite:
Adolescent
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Adult
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Humans
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Middle aged
Idioma:
En
Año:
2012
Tipo del documento:
Article