QuantiCl · Deconstructing the role of trans-cellular ion transport in organ formation and function

Solute transport across epithelial cells is of vital importance for the function and development of many organs, for instance, the pancreas, liver, and intestine. Within the pancreas, bicarbonate is secreted from the ducts in order to neutralize stomach acid in the duodenum. The secretion of bicarbonate over the epithelial membrane is coupled to chloride transport in the opposite direction. The mechanism of this transport is complex due to the redundancy of transporters, protein-protein interactions, and multiple regulation and signaling mechanisms. Thus far the field relies on either bulk measurements, for example using Ussing chambers, or studies on isolated individual proteins. A more profound and quantitative understanding of epithelial transport cannot be obtained solely by either of these strategies but requires a combination of both: addressing individual proteins within their native cellular environment. Therefore, I will establish the contribution of individual transporters in epithelial chloride transport in human pancreatic duct cells by using inhibiting nanobodies to perturb the system. Then I will determine the plasticity and response of the cells to these inhibitions by measuring protein expression using transcriptomics and quantitative mass-spectrometry. Next, I will perform quantitative chloride measurements across epithelial cells, simulating in-organ conditions by changing the composition of the apical solution. Finally, I will elucidate the role of chloride transport in pancreatic duct formation by inhibiting key chloride transporters in 3D pancreatic organoids. Taken together this project will yield quantitative insights into transcellular chloride transport, within the full complexity of the native cellular environment.