MPK38 expression is upregulated in immature T cells activated by concanavalin A

Abstract

We have previously identified a cDNA clone from a murine teratocarcinoma PCC4 cDNA library, which we have termed MPK38 for murine protein kinase 38. MPK38 is a new member of the SNF1 serine/threonine kinase family. To understand the role of the MPK38 in thymocytes, we have investigated the level of MPK38 expression by Northern blot analysis. Interestingly, incubation of thymocytes at 37°C resulted in the loss of the MPK38 transcript, however the transcript could be reinduced by treatment with Con A or PHA, but not with PMA and growth factors such as IL-2, IL-7, TGF- β, TNF- α, and EGF. In addition, stimulation of mature T cells from the spleen with Con A failed to reinduce the MPK38 transcript, indicating a developmental regulation of MPK38 expression, whereas non-T cell populations significantly reinduced the transcript. These results suggest that MPK38 may play a functional role as one of the signal regulators in early T cell activation and, potentially, certain lineages of hematopoietic cell activation induced by Con A.