Role of citrullination and proteolysis in cancer and viral infection.
We are focused on understanding how post-translational modifications (citrullination, methylation, and proteolysis) alter the regulation of biological pathways in diseases and infection and develop novel diagnostics and therapeutic strategies targeting these post-translational modifications (PTMs). We utilize a combination of chemical biology, molecular biology, chemoproteomics, enzymology, and biochemical approaches to understand these complex biological questions.
The current projects are focused on mainly two areas: 1) understanding how protein citrullination disrupts the regulation of key protease cascades leading to thrombosis and inflammation in multiple pathologies; and 2) understanding how viral proteases interfere with host protease cascades to invade into the host system.
The Role of Protein Citrullination in Pathological Thrombosis Thrombosis is the formation of blood clots inside the blood vessel, obstructing the blood from flowing naturally through the circulatory system. Thrombosis is commonly seen in patients with cancers and autoimmune diseases. More than 2 million people die each year of thrombosis or its consequences in the united states. Despite this, the mechanism of pathological thrombosis remains poorly understood.
Recent studies suggest that protein citrullination—a post-translational modification (PTM) of arginine-- plays a role in thrombus formation. Notably, the coagulation cascade that maintains proper blood flow in the body is regulated by arginine-specific serine proteases. How protein citrullinated alters the regulation of arginine-specific serine proteases during thrombosis remains unknown, mainly because of the technical challenges associated with identifying citrullinated proteins, i. e., the mass change upon citrullination is only 0.98 Da. Our lab is pioneering in developing innovative proteomic techniques to study this tiny but essential PTM. The ultimate goal of this project is to understand how protein citrullination alters the coagulation cascade protease signaling. Our studies are likely to open new directions to study the regulation of arginine-specific proteases in health and diseases.
Host Substrate Profiling of SARS-CoV-2 Virus Protease Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the viral pneumonia outbreak of coronavirus disease 2019 (COVID-19), causing widespread morbidity and mortality. Main protease (Mpro) encoded by SARS-CoV-2 processes the viral polyproteins and facilitate viral replication. Once activated, this enzyme can evade the host innate immune responses by cleaving host proteins. The host protein substrates of SARS-CoV-2 Mpro are not well characterized because the direct detection of host protein targets remains challenging due to is their low abundance and technical limitations with the specificity and sensitivity of the current methods. We are developing a more specific and sensitive N-terminomics approach to discover unique protein fragments generated by Mpro during SARS CoV-2 infection. The ultimate goal of this project is to understand the impact of Mpro proteolytic events on the coronavirus invasion. Our studies are likely to open new directions to study host cellular pathways hijacked by pathogens to invade the host system.
- Tilvawala R*, Nguyen SH*, Maurais AJ*, Nemmara VV, Nagar M, Salinger AJ, Nagpal S, Weerapana E and Thompson PR. The Rheumatoid-arthritis Associated Citrullinome. Cell Chem Biol., 2018, 25, 1-14. (*Co-first authors).
- Tilvawala R and Thompson PR. Protein Arginine Deiminase: Detection and Functional Analysis of Protein Citrullination. Curr. Opin. Stru. Bio., 2019, 20, 1-11.
- Nemmara VV, Tilvawala R, Salinger AJ, Nguyen SH, Miller L, Weerapana E and Thompson PR. Citrullination Inactivates Nicotinamide-N- methyltransferases. ACS Chem Biol., 2018, 13, 2663-2672.
- Sorvillo N, Mizurini DM, Martinod K, Coxon C, Tilvawala R, Cherpokova D, Salinger AJ, Staudinger C, Seward RJ, Costello CE, Thompson PR and Wagner DD. Plasma Peptidyl Arginine Deiminase IV Promotes VWF Platelet String Formation and Accelerate Thrombosis after Injury. Circ. Res., 2019, 125, 507-519.
- Nagar M, Tilvawala R and Thompson PR. Thioredoxin Modulates Protein Arginine Deiminase 4 (PAD4)-Catalyzed Citrullination. Front. Immunol., 2019, 10, 1-10.