Figure 6.

Application of in vitro cellular intestinal models to study intestinal zinc transport. Schematic representation of the three-dimensional intestinal Caco-2/HT-29-MTX co-culture model. (A) Zinc is quantified in all three compartments (apical, cellular, basolateral) with conventional analytical approaches, such as inductively coupled mass spectrometry (ICP-MS) or flame atomic absorption spectrometry (FAAS). (B) The application of chemical-based or protein-based fluorescent zinc sensors in enterocytes provides additional information about the subcellular distribution of the micronutrient upon its uptake into the cell. These sensors bind intracellular free zinc and track small changes of this zinc moiety. Depending on the subcellular localization of the sensor, the cytoplasmic free zinc pool or free zinc in organelles, such as vesicles and the endoplasmic reticulum (circled in red) can be investigated.