Activation of MAP-2 kinase activity by the CD2 receptor in Jurkat T cells can be reversed by CD45 phosphatase
Department of Molecular Genetics and Microbiology
Medical Subject Headings
Antibodies, Monoclonal; Antigens, CD; Antigens, CD2; Antigens, CD3; Antigens, CD45; Antigens, Differentiation, T-Lymphocyte; Blotting, Western; Calcium-Calmodulin-Dependent Protein Kinases; Cell Line; Histocompatibility Antigens; Humans; Kinetics; Leukemia, T-Cell; Phosphorylation; Phytohemagglutinins; Protein Kinases; Receptors, Antigen, T-Cell; Receptors, Immunologic; T-Lymphocytes
Microbiology | Molecular genetics
We have recently characterized a serine kinase in T lymphocytes which phosphorylates microtubule-associated protein-2 (MAP-2) in vitro. This kinase is activated in a rapidly reversible fashion during ligation of CD3/Ti by a process which involves tyrosine phosphorylation of the enzyme itself. We show that the stimulatory anti-CD2 mAb combination, anti-(T11(2) + T11(3), stimulates MAP-2K activity in Jurkat cells with kinetics that are more prolonged than during anti-CD3 treatment. The principal difference is not in the rate of response induction, but in the decline of the response beyond the peak, to which end anti-CD2 stimulation resembles the sustained phytohaemagglutin (PHA) response. Parallel immunoblotting, utilizing anti-phosphotyrosine antibodies, also revealed differences in the rate at which tyrosine phosphorylation of pp43 (MAP-2K) disappears after induction. In spite of these differences, CD2 was absolutely dependent on the presence of CD3 for inducing a MAP-2K response in Jurkat cells. These results indicate that, even though CD2 and CD3 are using a common signalling pathway in Jurkat cells, additional differences such as the involvement of a tyrosine phosphatase may have to be considered in response generation. We also demonstrate that the common CD45 isoform, when cross-linked to CD2 by mAb, could inhibit the MAP-2K response during both induction as well as the disappearing phase of the response.
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Citation: Immunology. 1991 Jun;73(2):129-33.