RAPID: What is the role of extracellular vimentin in SARS2 host cell entry?

This project will determine the mechanisms by which cell surface vimentin modulates the cellular uptake of the novel virus SARS-CoV-2 (SARS2). Vimentin is an intermediate filament that forms part of the cellular cytoskeleton. New evidence indicates that vimentin is present on the extracellular surface of cells and plays a critical role in the binding and uptake of multiple viruses; yet, the mechanisms by which this happens remain unclear. Identifying the factors that regulate cell surface vimentin and how it interacts with SARS2 will provide new insight into new functions of cell surface vimentin and the fundamental mechanisms by which viruses infect cells. There is an urgent need for this information as we have an incomplete understanding of how this virus enters the cell. This project integrates techniques from physics, engineering, chemistry, and biology and will broaden participation in the field of biophysics by providing interdisciplinary training for graduate students and postdocs.

Host cell entry of SARS2 is not yet fully characterized, but inhibition of both endocytosis and direct fusion are known to be preventative. SARS2 makes use of a spike protein to interact with the angiotensin converting enzyme 2 (ACE2) cellular receptor to drive host cell entry via membrane fusion. The membrane fusion pathway for SARS2 is, therefore, similar to SARS-CoV (SARS), the virus that genetically most closely resembles SARS2. Endocytosis is another dominant pathway for host cell entry, but the mechanisms involved remains largely unknown. Previous studies indicate that SARS host cell entry via endocytosis critically involves cell surface vimentin. This project aims to determine the role of cell surface vimentin in SARS2 cellular uptake. This project pursues the following three objectives: 1) determine the presence and the factors that regulate extracellular vimentin using fibroblasts and lung epithelial cells; 2) study the effect of extracellular vimentin on SARS2 viral uptake and determine whether viral uptake can be blocked by anti-vimentin antibodies; and 3) quantify the molecular interaction between vimentin and the spike protein of SARS2. These studies will be conducted using SARS2 virus-like particles. Results from molecular dynamics simulations will provide an interpretative framework for the experimental results.

This RAPID award is made by the Cellular Dynamics and Functionl Program in the Division of Molecular and Cellular Biosciences, using funds from the Coronavirus Aid, Relief, and Economic Security (CARES) Act.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.