Mitogenic activation, involvement

KC706 stabilizes the inactive conformation of the mitogen-activated protein kinase p38a, a protein kinase involved in inflammatory reactions and cardiovascular functions. KC706 therefore holds the potential to treat conditions such as rheumatoid arthritis, psoriasis, inflammatory bowel disease and cardiovascular disease. This compound is currently being tested in phase II clinical trials with patients suffering from rheumatoid arthritis. 

Ogilvie P, Thelen S, Moepps B, et al. Unusual chemokine receptor antagonism involving a mitogen-activated protein kinase pathway. J Immunol 2004 172 6715-6722. 

Fiebich, B. L., Schleicher, S., Spleiss, O., Czygan, M. and Hull, M. Mechanisms of prostaglandin E2-induced interleukin-6 release in astrocytes possible involvement of EP4-like receptors, p38 mitogen-activated protein kinase and protein kinase C. /. Neurochem. 5 950-958,2001. 

Figure 21.9 The mitogen-activated protein kinase cascade (MAP kinase cascade). The active protein Ras activates Raf by promoting its recruitment to a cell membrane. Through a series of phosphorylations MAP kinase is activated as follows MAP kinase kinase kinase (Raf) phosphorylates MAP kinase kinase which, in turn, phosphorylates MAP kinase, the final target enzyme. MAP kinase phosphorylates transcription factors for genes that express proteins involved in proliferation. Another nomenclature for the enzymes is also used raf is MEKK MAPKK is MEK and finally ERK is MAP kinase (ERK is the abbreviation for extracellular-signal-related kinase) For comparison, the reader is referred to the metabolic phosphorylase cascade, which is discussed in Chapter 12 (Figure 12.12).

The various organs of the immune system such as spleen, lymph nodes, thymus and bone marrow containing the cells involved in the various immune responses offer the possibility to harvest these cells and perform in vitro assays for evaluation of effects on the immune system. When part of an in vivo animal study this may indicate a direct toxic effect of pharmaceuticals, that is, immunosuppression (Table 18.2). So, it is feasible to obtain cell suspensions for further evaluation such as determination of cellular subsets of T and B leukocytes by fluorescent activated cell sorter analysis (FACS analysis), and determination of natural killer (NK) cell activity of the spleen cell population. An advantage of this approach is that it may lead to identification of a biomarker to be used in clinical studies. In addition, in vitro stimulation of spleen cells with mitogens activating specific subsets may indicate potential effects on the functionality of splenic cell populations. Concanavalin A (Con A) and phytohemagglutinin (PHA) activate Tcells, while lipopolysaccharide (LPS) activates primarily B cell populations. Blood is collected for total white blood cell (WBC) determination and blood cell differential count. In addition, serum can be obtained for determination of serum immunoglobulins. 

G5. Graves, J. D., Draves, K. E., Craxton, A., Saklatvala, J., Krebs, E. G., and Clark, E. A., Involvement of stress-activated protein kinase and p38 mitogen-activated protein kinase in mIgM-induced apoptosis of human B lymphocytes. Proc. Natl. Acad. Sci. U.S.A. 93, 13814— 13818 (1996). 

Kawasaki, H., Morooka, T., Shimohama, S., Kimura, J., Hirano, T., Gotoh, Y., and Nishida, E., Activation and involvement of p38 mitogen-activated protein kinase in glutamate-induced apoptosis in rat cerebellar granule cells. J. Biol. Chem. Ill, 18518-18521 (1997). 

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