A dynamic, cytoplasmic tryacylglycerol pool in enterocytes revealed by ex vivo and in vivo coherent anti-Stokes Raman scattering imaging .

摘要

Obesity results from an imbalance between energy uptake and metabolic expenditure of energy. Dietary fat absorption (DFA) via the small intestine is a key step in the mechanism of obesity. Understanding how environmental factors and molecular pathways affect the process of DFA could provide various clues for tackling the obesity epidemic. In specific, in mammals, the absorptive cells of the small intestine, enterocytes, are not generally thought of as a cell type that stores triacylglycerols (TGs) in cytoplasmic lipid droplets. We revisit TG metabolism in enterocytes by ex vivo and in vivo coherent anti-Stokes Raman scattering (CARS) imaging of small intestine of mice during DFA. We directly visualized the presence of lipid droplets (LDs) in enterocytes and the LDs were confirmed to be primarily TG by biochemical analysis. Combined CARS and fluorescence imaging showed that the large LDs were located in the cytoplasm, associated with the tail-interacting protein of 47 kDa (TIP47). Furthermore, intravital CARS imaging showed real-time variation in the amount of TG stored in LDs through the process of DFA. Our results highlight a dynamic, cytoplasmic TG pool in enterocytes which may play previously unexpected roles in processes such as regulating postprandial blood TG concentrations.