DAVID HO

Home Department
Cell and Developmental Biology

Thesis Advisor
Lee Bardwell - Cell and Developmental Biology

Co-thesis Advisor
Pierre Baldi - Information and Computer Science

Email


Mitogen-Activated Protein Kinase (MAPK) pathways enable cells to respond appropriately to extracellular signals and stresses. Specificity of interaction between MPKs and their respective upstream activator MAPK kinases (MKKs, or MEKs) is crucial to assure accurate signal transmission. Previous work has demonstrated the important role of a docking site on the N-terminus of MEK1 and MEK2 in binding ERK. The MEK docking sites provide another level of specificity in addition to the interaction with the active site of the substrate MAPK. Based on sequence homology, putative docking sites have been proposed for other mammalian MKKs, including MKK4 and MKK7, which both activate the JNK family of MAPKs and also p38 in the case of MKK4. The focus of my project has been to test these putative docking sites for their ability to promote specific, high-affinity interactions with the respective MAPKs.

Through in vitro binding assays, David Ho’s work has demonstrated that the MKK4 docking site is both sufficient and necessary for binding to downstream MPKs JNK and p38. In addition, he has used in vitro kinase assays to show that the MKK4 docking site is important for optimal phosphorylation of JNK. Currently, he is performing experiments to demonstrate this role of the MKK4 docking site in vivo.
As opposed to the single docking site in MKK4, MKK7 appears to have three putative N-terminal docking sites. David’s in vitro experimentation has shown that all three collectively seem to promote specific interaction with JNk. However, the putative docking sites do not seem to be able to bind JNK individually. Thus, he will examine the possibility that the three docking motifs work together in a synergistic way.

Publications

Ho, D., Bardwell, A.J., Abdollahi M., and Bardwell, L. A docking site in MKK4 mediates high-affinity binding to JNK MAP kinases and competes with similar docking sites in JNK substrates. Journal of Biological Chemistry (submitted).