Leukemia T Cells as a Model to Study the Activity of the Phosphatase PP4 in the Regulation of T Cell Response | Chapter 1 | Recent Developments in Medicine and Medical Research Vol. 13

 T cell cell lines derived from human leukaemia cells are useful tools for studying both basic and practical aspects of T cell biology. The leukaemia cells have several advantages, including the capacity to replicate the normal activity of T cells and the availability of similar cell material all over the world. They can also be cryopreserved. The phosphatase enzyme PP4 is a serine/threonine protein phosphatase that shares 65 percent amino acid similarity with PP2A and is okadaic acid-sensitive. Protein phosphatase has been implicated in the control of T-cell signalling and activation in numerous studies. In Jurkat leukaemia T cells that had previously been stimulated with UV, TPA, Ionomycin, and Okadaic acid, the effect of overexpression of PP4 on the expression of a member of the MAP kinase family was studied. In the absence of any form of stimulation, we discovered that overexpression of PP4 displayed relatively low activity. TPA, UV, or Ionomycin therapy, on the other hand, significantly boosts PP4 activity. Furthermore, Jurkat T cells transfected with various expression plasmids and/or treated with TPA, UV, or Ionomycin substantially trigger JNK and p38, whereas the ERK-1/2 kinase pathway is activated on a weekly basis. Treatment of Jurkat T cells with okadaic acid, a PP2 phosphatase inhibitor, also inhibits PP4-induced increases in JNK and p38 activity. The effect of okadaic acid on PP4 activity was comparable to that seen in Jurkat T cells treated with a c-Jun dominant negative (dn-jun). These findings suggest that the PP4 phosphatase activity in Jurkat leukemic T cells targets JNK and p38 activation but not ERK activation.

Author(S) Details

Eduardo Parra
Biomedical Experimental Laboratory, School of Medicine, Campus Saucache, University of Tarapaca, Avenida General Velázquez 1775, Arica, Chile.

Pedro Hecht
Biomedical Experimental Laboratory, School of Medicine, Campus Saucache, University of Tarapaca, Avenida General Velázquez 1775, Arica, Chile.

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