Okadaic Acid, RK682 and Calyculin Modulate TcR - Mediated Signaling Events.
- Author:
Sang Kyou LEE
;
Jung Hee LIM
;
Kyung Min CHO
;
Hyun Jung KIM
;
Sang Won KIM
;
Young Sup SONG
- Publication Type:Original Article
- Keywords:
Calyculin;
RK682;
Immunosuppressive Drug;
NF-AT
- MeSH:
Antigen-Presenting Cells;
Antigens, Viral, Tumor;
Binding Sites;
Cell Line;
Cytoplasm;
Gene Expression;
Humans;
Interleukin-2;
Jurkat Cells;
Okadaic Acid*;
Phosphorylation;
Receptors, Antigen, T-Cell;
T-Lymphocytes;
Tyrosine
- From:Korean Journal of Immunology
1997;19(3):327-336
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
The T cell antigen receptor (TcR) in combination with costimulatory signals triggered by accessory molecules present on the surface of the antigen-presenting cells (APC) regulates the activation and growth of T lymphocytes. Calyculin A and Okadaic acid is known to be an inhibitor of serine/threonine phosphatase and RK-682 specifically blocks functions of tyrosine phosphatase. To investigate roles of these inhibitors in TcR-mediated signaling cascade, chimeric molecule CD8-5 which contains the extracellular and transmembrane domains of the human CD8a molecule and the cytoplasmic tail of TcR 5 chain were stably expressed in Jurkat cell line. CD8-5 chimeric protein induced tyrosine phosphorylation of various cytoplasmic substrates and IL-2 gene expression in a NFAT dependent manner by stimulation with anti-CD8 mAb OKT8 as seen in TcR stimulation. When CD8-5 transfectants were preincubated with Okadaic acid, Calyculin or RK682, they differentially affected tyrosine phosphorylation of signaling mediators including CD8-5 molecule. When Jurkat Tag cell line was used where SV40 T antigen is stably expressed and the expression of p-galactosidase is driven by the multiple NFAT binding sites plus minimal IL-2 promoter, these phosphatase inhibitors -RK682, Calyculin A, Okadaic acid- effectively inhibited IL-2 gene expression at the concentration of 1.2832 x 10 ' M, 3.9924 x 10 M, 7.2707 x 10 M respectively. These results suggested that Okadaic acid, Calyculin or RK682 modulate TcR-proximal as well as TcR-distal signaling events during T cell activation.
