Proteomics and Cell Signaling

Jürgen Kast, Ph.D.
Department of Chemistry UBC, Professor
Centre for Blood Research, Member

Research Summary

Panta rhei – everything flows. Indeed, most cells in the human body are subject to perpetual change. Old or dysfunctional cells are replaced on a regular basis. In addition, each cell is constantly sensing its environment, and can adapt in response to specific cues, if necessary. This is essential to ascertain proper physiological function. For example, proteins and small molecules guide the migration of leukocytes to sites of infection or injury. Some of these factors are released by platelets upon activation, initiated by proteins that are exposed in the vasculature after injury. Conversely, endothelial cells lining the vasculature continuously release signaling molecules to keep platelets in their resting state. This prevents untimely activation and aggregation, which could lead to blood clot formation and blocked blood vessels. Disturbing this delicate balance will inevitably result in the onset of severe illnesses. For platelets, this can range from stroke and myocardial infarction to compromised blood clotting and bleeding disorders, including ulcers. For leukocytes, chronic inflammation, autoimmune diseases, or compromised immune systems may be set off.

Current treatment strategies to restore balance typically involve administration of drugs. For example, aspirin is a non-steroidal anti-inflammatory drug that chemically modifies and irreversibly blocks cyclooxygenase, an enzyme involved in the synthesis of thromboxanes and prostaglandins. The suppressed production of these signaling molecules results in pain relief, reduction of fever, increased release of nitric oxide to regulate inflammation, but also suppression of blood clotting, hence prolonged bleeding and ulcers are unwanted side effects of this classic blockbuster drug. In cases such as this, knowing the changes that cause the imbalance, or the targets of existing drugs that are used for treatment, will benefit the development of improved interventions. Detailed knowledge of how these changes come about often also reveals unexpected links. Platelet activation and leukocyte migration rely on essentially identical basic processes to convert external into internal signals that ultimately result in the modulation of the cytoskeleton, an essential step for any change of cell shape. Remarkably, similar processes also govern the migration of cancer cells in and out of tissue in metastasis. Understanding what controls these mechanisms is therefore key to developing optimized treatments not only for inflammation, stroke and infarction, but also cancer metastasis.

All signal transduction processes consist of individual protein-protein interactions, which are assembled into pathways and networks. They are regulated by protein abundance and localization, and modulated by post-translational modifications. Any drug intervention therefore must alter at least of these features in order for it to be effective. Moreover, an analytical technique capable of obtaining this information has to be used to detect the method of action of a drug. Mass spectrometry-based proteomics is a powerful and versatile tool that can be used for protein identification, but also to characterize global and local protein expression patterns, protein interaction environments, and protein modifications, as well as to quantitatively compare different cellular states. We are relying heavily on this analytical technique to determine how cells are set up and work, what changes they undergo that impair their function, and how drugs can reconcile them. We also employ protein and peptide fractionation and enrichment strategies, protein chemistry applications, and computational data processing. Our current subjects of study are the interaction of platelets with their environment and the organization of GTPase interaction networks.

We are interested in training graduate students and post-graduate fellows.

Selected Publications

Thon JN, Schubert P, Duguay M, Serrano K, Lin S, Kast J, Devine DV. Comprehensive proteomic analysis of protein changes during platelet storage requires complementary proteomic approaches. Transfusion. 2007 Dec 7; [Epub ahead of print]

Schubert P, Hoffman MD, Sniatynski MJ, Kast J. Advances in the analysis of dynamic protein complexes by proteomics and data processing. Anal Bioanal Chem. 386(3):482-93 (2006)

Hoffman MD, Sniatynski MJ, Rogalski JC, Le Blanc JC, Kast J. Multiple neutral loss monitoring (MNM): a multiplexed method for post-translational modification screening. J Am Soc Mass Spectrom. 17(3):307-17 (2006)

Sniatynski MJ, Rogalski JC, Hoffman MD, Kast J. Correlation and convolution analysis of Peptide mass spectra. Anal Chem. 78(8):2600-7 (2006)

Rogalski, J.C., Lin, M.S., Sniatynski, M.J., Taylor, R.J., Youhnovski, N., Przybylski, M., Kast, J. Statistical Evaluation of Electrospray Tandem Mass Spectra for Optimized Peptide Fragmentation. J. Am Soc. Mass Spectrom 16, 505-514 (2005)

Vasilescu, J, Guo, X, and Kast, J. Identification of Protein-Protein Interactions Using In Vivo Cross-linking and Mass Spectrometry, Proteomics. 4: 3845-54 (2004)

Lab Members