A chemical and synthetic biology approach for post-trancriptional gene regulatory networks and therapeutic generation

• Applicant: Yollete Guillen Schlippe, Ph.D.
• Subject Area: Biochemistry ; Biological and Biomimetic Chemistry
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 396644804

There is abundant evidence that posttranscriptional gene regulation (PTGR) plays a central role in controlling gene output. At the heart of eukaryotic PTGR is one of the largest macromolecular assembly in the cell: the ribosome. Initiation is the rate-limiting step of translation and is frequently targeted for regulation, more so than any other steps in the gene expression pathway. Most translation initiates with the eIF4F complex recruiting the small subunit of the ribosome to the cap structure at the 5-prime end of mRNA, a process termed cap-dependent initiation. During key biological processes including development, the cell cycle, and apoptosis, the eIF4F complex is disrupted, resulting in a mechanistic shift to cap-independent initiation and the preferential translation of certain key mRNAs. Proper regulation of cap-dependent translation is, therefore, essential for normal cell function such that high levels of eIF4F results in malignant transformation while decreasing levels of eIF4F have anti-tumor activity. Importantly, the discovery of molecules that modulate the activity of eIF4F could provide an effective therapy against a wide array of cancers, potentially overcoming the challenges of chemoresistance and intra-tumor heterogeneity. Furthermore, translation initiation regulation is poorly understood due to a lack of tools capable of dissecting the complex, intertwined interactions between canonical and non-canonical initiation factors, RNA structures, and RNA modifications. To interrogate such systems, I have developed a highly efficient and powerful discovery technology platform that allows for the rapid enzymatic synthesis, selection, and evolution of bioactive peptides from extremely diverse libraries containing over a trillion different molecules. With the bipartite goal of dissecting molecular mechanisms of PTGR and generating therapeutic lead molecules that alter the PTGR network, we will 1) further develop this technology for the convenient chemo-enzymatic synthesis of stapled alpha-helical peptide libraries amenable for selections on RNA-binding proteins 2) screen the stapled peptide libraries for modulators of eIF4F activity and perform mechanistic characterizations of these peptides for their effect on cap-dependent and independent translation in vitro, and 3) test the synthetic peptide modulators to selectively kill cancer cells and use the peptides as molecular tools to disentangle in vivo features of PTGR networks. Achieving these goals will allow us to combine mechanistic investigations with genome-wide approaches, thereby bridging new biological insights to drug discovery.

• DFG Programme: Research Grants