Abstract LB036: Back and forth from structure to functional target: The interplay between Vimentin and non-canonical nucleic acid arrangements
Authors: Sissi Claudia , Cozzaglio Marta , Rigo Riccardo , Dal Ponte Nicolo , Rotondo Martina , Ceschi Silvia , BIondi Barbara , Spolaore Barbara 
Published: April 2024

Abstract
Vimentin, a member of type III intermediate filaments (IFs), is a cytoskeletal protein that covers multiple architectural and functional roles, including the maintenance of organelle positioning in the cytoplasm, the regulation of cytoskeletal rearrangements, while more recently its potential involvement as a regulatory factor in gene expression emerged. Additionally, it is involved in cell migration and epithelial-to-mesenchymal transition (EMT). In previous works, we identified Vimentin as the first known protein that selectively binds G-quadruplexes repeats (G4-repeats). This DNA folding consists of repeated units of nucleic acid sequences arranged into G-quadruplex (G4s). Their three-dimensional features largely differ from the most common single-stranded or double-helix nucleic acids as well as from the isolated G4 modules. Noteworthy, they occur at a small subset of genomic sites, associated with cell proliferation and migration, where they can recruit the soluble nuclear pool of Vimentin. Altogether, this information led us to consider the Vimentin-DNA complex as a promising target for developing small molecule binders capable of inhibiting cell migration and, eventually, EMT. To properly set up a rational drug-design approach, we integrated different advanced biophysical tools (Hydrogen-Deuterium Exchange, Cryo-Electron Microscopy) to derive a comprehensive picture of the protein-DNA complex at the molecular level. This approach allowed us to map the interaction surface between the soluble tetrameric form of Vimentin and a G4-repeat. Based on this data, we initiated a screening campaign using focused libraries of small molecules and peptides, which were rationally designed according to the structural features of the Vimentin-G4-repeats complex. The capability of the identified hits to prevent the recognition of the nucleic acid by Vimentin has been investigated This approach allowed us to identify attractive novel entities that prevent the Vimentin-G4-repeat complex formation according to different molecular mechanisms. These systems are now under further refinement moving from the test tube to the cellular environment, where the dynamic behavior of these nucleic acid domains as well as the recruitment of different proteins by Vimentin might alter the architectural features of the target.
References: Ceschi S, Berselli M, Cozzaglio M, Giantin M, Toppo S, Spolaore B, Sissi C (2022) Vimentin binds to G-quadruplex repeats found at telomeres and gene promoters Nucleic Acid Res, 50(3):1370-1381 Buglione E, Salerno D, Marrano CA, Cassina V, Vesco G, Nardo L, Dacasto M, Rigo R, Sissi C, Mantegazza F (2021) Nanomechanics of G-quadruplexes within the promoter of the c-kit oncogene. Nucleic Acid Res, 49, 4564-4573
Citation Format: Claudia Sissi, Marta Cozzaglio, Riccardo Rigo, Nicolo Dal Ponte, Martina Rotondo, Silvia Ceschi, Barbara BIondi, Barbara Spolaore. Back and forth from structure to functional target: The interplay between Vimentin and non-canonical nucleic acid arrangements [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB036.