Characterization of JNK Binding Proteins: A Dissertation

The JNK signal transduction pathway mediates a broad, complex biological process in response to inflammatory cytokines and environmental stress. These responses include cell survival and apoptosis, proliferation tumorigenesis and the immune response. The divergent cellular responses caused by the JNK signal transduction pathway are often regulated by spatial and cell type contexts , as well as the interaction with other cellular processes. The discovery of additional components of the JNK signal transduction pathway are critical to elucidate the stress response mechanisms in cells. This thesis first discusses the cloning and characterization of two novel members of the JNK signal transduction pathway. JIP1 and JMP1 were initially identified from a murine embryo library through a yeast Two-Hybrid screen to identify novel JNK interacting proteins. Full length cDNAs of both genes were cloned and analyzed. JIP1 represents the first member of the JIP group of JNK scaffold proteins which were characterized. The JNK binding domain (JBD) of JIP1 matches the D-domain consensus of other JNK binding proteins, and it demonstrates JNK binding both in vitro and in vivo. This JNK binding was demonstrated to inhibit JNK signal transduction and over-expression of JIP1 inhibits the JNK mediated preB cell transformation by bcr-abl Over-expressed JIP1 also sequesters JNK in the cytoplasm , which may be a mechanism of the inhibition of JNK signaling. A new, high-resolution digital imaging microscopy