Post-translational modifications of proteins in neutrophil immune responses

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The long-term objective of my research program is to understand how neutrophils facilitate the immune response. The NSERC-DG program focuses on the direct (Obj 1) and indirect (Obj 2) role of post-translational modifications on neutrophil protein function. Neutrophils are responsible for the initial response to an invading pathogen. Neutrophils form proteins that are stored within the cell that are released rapidly upon stimulation (degranulation). These proteins function primarily through their potent, short-lived enzymatic activity. Post-translational modifications (PTM) of proteins are single amino-acid alterations that leads to functional changes in proteins and represent an elegant method of maintaining protein homeostasis. Neutrophils can induce many of these changes, particularly when they encounter pathogens. An example of a PTM that is mediated by neutrophils is citrullination, which alters an amino acid called arginine. This modification leads to a change in the charge of the amino acid, which can have significant impact on the way a protein folds and ultimately functions. Regulation of the immune response occurs at many different levels. For example, gene transcription can be altered through proteins (transcription factors) or by modifying the structure of DNA (epigenetics). After protein translation, PTMs can play a similar role, however the precise changes that immune cells use to tune their immune responses via PTMs are not well understood. We will investigate how neutrophils introduce protein alterations to efficiently neutralize pathogens. The proposed methods use recombinant neutrophil proteins, which are then exposed to conditions that facilitate PTMs, activity-based proteomics is then used to profile alterations in function. Key alterations are profiled using site-specific mass spectrometry. In addition, we will determine the mechanisms by which modified neutrophil proteins can facilitate crosstalk with other immune cells or proteins. My NSERC-DG program aims to uncover novel immunological mechanisms using proteomic approaches. This is representative of a new approach to studying the immune system. Fundamental knowledge generated from this proposal will provide opportunities for me to train HQP in interdisciplinary techniques and enhance the understanding of the mechanisms that neutrophils use to neutralize pathogens, communicate with other cells, and ultimately mediate inflammation to protect the host. The impact of this work will be felt amongst immunologists and biochemists, who also aim to understand how proteomic alterations, in this case those generated on neutrophil proteins, impacts the functionality of enzymes. Conclusions generated from this program will offer new insights into how molecular alterations help maintain the extracellular environment and protection of the host. I plan to train 1 MSc student, 1 PhD student and 5 undergraduate students in this cycle of my program.