Cellular processes such as growth, death and differentiation are regulated by interactions between proteins in the cell. Disruption of a protein-protein interaction (PPI) is a useful tool to study its significance in a given cellular context. The goal of this project is to develop a class of compounds that specifically inhibit PPIs of interest. Specifically, inhibitor compounds targeting a model PPI of relevance in cancer and human embryonic stem cells (hESCs) will be developed. If successful, the results from this project will have significant broader scientific impact as an enabling tool for cell biology, and applications involving stem cells in particular. Furthermore, inhibitor compounds may be attractive as drug candidates. Research activities undertaken will also be integrated with a plan for education and K-12 outreach, including hosting a high school teacher in the PI's lab and engaging with high school students through a stem cell themed workshop to create general awareness of the science, technology, ethics and regulation of stem cell research.
Cell-permeable small molecules represent a powerful tool for inhibiting PPIs. However, the use of these compounds is often limited by insufficient target specificity and potential toxicity. Furthermore, the identification of a small molecule capable of specifically inhibiting a given PPI in the intracellular milieu is not trivial. To overcome these limitations, it is proposed to design bi-cyclic peptides for specific inhibition of intracellular PPIs, wherein one cyclic moiety enables cell penetration, and the second moiety selectively binds a specific region on the target protein. In Objective 1, mRNA display libraries will be screened to identify cyclic moieties that mediate cell penetration. In mRNA display, each peptide is linked to its coding sequence. Peptides with desired properties are selected from the library of nucleic acid-peptide hybrids and identified by DNA sequencing. In Objective 2, a mRNA-display library of bi-cyclic peptides containing a cell penetrating moiety will be screened to identify cyclic peptide moieties that disrupt a PPI mediated by beta-catenin. Finally, under Objective 3, the bi-cyclic peptide inhibitors will be validated through experiments in HEK293T cells. Subsequently, the validated inhibitor will be used to investigate the role of the target PPI in hESCs. To facilitate K-12 outreach, the PI will host a high school teacher as part of the Kenan Fellows Program - a prestigious year-long fellowship program for North Carolina K-12 public school teachers designed to advance and retain exceptional science, technology, engineering and mathematics (STEM) educators. Additionally, the PI will engage with high school students through a stem cell themed workshop. Key aspects of the proposed research will be incorporated into courses currently offered by the PI and undergraduate students will be actively involved in targeted research projects that contribute to the overall goals of this project. Participation of women and minority students will be particularly encouraged.
This award by the Biotechnology and Biochemical Engineering Program of the CBET Division is co-funded by the Cellular Dynamics and Function Program of the Division of Molecular and Cellular Biology.
