Date of Award
Doctor of Philosophy (PhD)
Cell Biology and Biochemistry
Jie J. Zheng, Ph.D.
Taosheng Chen, Ph.D. Eric J. Enemark, Ph.D. David R. Nelson, Ph.D. Susan E. Senogles, Ph.D.
Cell migration is an integrated multistep process accompanying us throughout life, from birth to death. It contributes to a variety of biological activities and has been implicated in many pathological conditions, including cancer, primary immunodeficiency diseases, vascular diseases, and mental retardation. Cell migration has been considered to be a three-step cyclic process including polarization, protrusion and retraction. The initiation and extension of the protrusion is driven by actin polymerization, and is stabilized by attaching to the extracellular matrix (ECM) or adjacent cells. The cell-ECM attachment sites are named focal adhesions (FAs), which are dynamic, large protein complexes containing more than 100 proteins. p130cas is a Src substrate localized in FAs that functions in integrin signaling to promote cell motility, invasion, proliferation and survival. The Src homology 3 (SH3) domain of p130Cas can directly interact with Focal Adhesion Kinase (FAK), which is a non-receptor tyrosine kinase that prominently locates in FAs. FAK serves the dual functions of recruiting p130Cas to FAs and recruiting Src kinase to phosphorylate the p130Cas substrate domain (SD) to promote downstream signaling. p130Cas targeting to focal adhesions and undergoing tyrosine phosphorylation in responding to adhesion signal plays an important role in cell motility, invasion and survival. Mice lacking p130Cas revealed embryonic lethality due to defects associated with the disorganized actin cytoskeleton. Although the importance of p130Cas localization and phosphorylation is well established, how it targets FAs has not been elucidated. Previous study demonstrated that, the N-terminal SH3 domain is critical for p130Cas localization through interacting with FAK. Deletion of SH3 domain and Cas-family C-terminal homology domain (CCHD) impairs p130Cas FA localization ability. The C-terminal region of p130Cas has been proposed as a Cas family homology domain, which may adopt a similar folding formation to the FAK C-terminal Focal Adhesion Targeting (FAT) domain. The nature of the target protein for the p130Cas CCHD in promoting FAs localization is unclear. In this dissertation we study the FAs localization of both FAK and p130Cas for understanding the detailed mechanisms. I proposed to develop the helical constrained peptidomimetics for targeting the FAT domain of FAK as inhibitor in order to address how FAK interacts with paxillin through its FAT domain associating with LD motifs of paxillin. The peptidomimetic inhibitors provide opportunity as potential therapeutic targets to regulate FAK activity in FAs. In the second part I identified the binding partner of p130Cas CCHD in FAs and solved the structure of p130Cas CCHD complex with paxillin LD1 that first demonstrated the detailed mechanism of CCHD playing an important role in p130Cas FAs targeting.
Zhang, Chi , "Structural-based Investigation of FAK and P130Cas in Focal Adhesion" (2015). Theses and Dissertations (ETD). Paper 313. http://dx.doi.org/10.21007/etd.cghs.2015.0373.