Differentiating the biological effects of individual fatty acids in single cells

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Background. The long-term objective of my research program is to advance our basic understanding of how fatty acids (FA) contribute to mammalian cell biology. Based on our work, it is increasingly clear that two fundamental knowledge gaps remain: the role of individual FA, and how their effects differ across specific cell types. Thus, the proposed research combines modern molecular and knock out (KO) mouse approaches to advance our foundational knowledge regarding the biological role of individual FA, a topic that has historically remained elusive due to limitations in methodologies and models. My research program has revealed how families of FA impact cell biology, including cell membrane composition, signalling through lipid rafts and caveolae, and metabolism mediated by fatty acid desaturases. This work has also provided increasing evidence that individual FA have unique biological properties. FA are viewed as large families that include polyunsaturated fatty acids (PUFA), saturated (SAFA), monounsaturated (MUFA), and trans (TFA) despite marked structural differences (e.g., chain length, no. of double bonds, cis & trans geometry) that likely confer unique functional properties. As well, our work sparked a critical discussion about how, as a field, we have relied on overly simplistic approaches to the study of tissues that do not account for the diversity of cell types contained within these tissues. In pilot work, we established methods to isolate specific adult mammary cells and show distinct signalling responses to n-3 PUFA. Unexpectedly, we also observed that n-3 PUFA influences the ratio of luminal and myoepithelial daughter cells, suggesting a role for n-3 PUFA in stem cell biology. Thus, while studying individual FA within specific cell types was not previously possible, models and technology now exists to pursue these questions. Therefore, my short-term objectives are to examine the precise effects of major individual FA at the level of individual cell types. Objectives and Approach. Using cutting edge in vivo animal model systems, our short-term objectives are to investigate the effect of major individual PUFA, SAFA, MUFA and TFA on membrane lipid composition, signalling and gene expression in adult and stem cells. This work will be conducted in mouse KO models capable of isolating the effects of individual fatty acids. Mechanisms of action will be assessed from isolated cells at multiple levels including the cell membrane, cell signalling and gene expression. Significance. The proposed research will address basic gaps in our understanding of how individual fatty acids affect single cell types. This work is at the forefront of lipid nutrition research in Canada while also contributing to fields of metabolism and physiology. This research program will also significantly contribute to HQP training, providing 25 trainees with advanced technical and professional skills and making them highly competitive for a wide range of careers.