Project 2: Regulation of Endocytic Trafficking of CFTR

Dr. Swiatecka-Urban

Dr. Swiatecka-Urban is an Instructor in Pediatrics and Research Assistant Professor of Physiology

Dr. Swiatecka-Urban's long-term goal is to elucidate the endocytic trafficking pathway of the cystic fibrosis transmembrane conductance regulator (CFTR) in order to develop a strategy to correct defective endocytic trafficking of F508-CFTR in individuals with Cystic Fibrosis (CF). F508, the most common mutation in CF causes: (1) retention of CFTR in the endoplasmic reticulum (ER), (2) reduced open probability of the CFTR Cl channel, and (3) decreased plasma membrane half-life of CFTR. Thus, correction of the defects caused by the F508 mutation will require a combination therapy that includes: (1) increased exit from the ER (2) increased Cl channel activity, and (3) increased plasma membrane half-life. Of these points, particularly little is known about the mechanisms that regulate the plasma membrane half-life of 508-CFTR. The hypothesis to be tested in this proposal is that the short plasma membrane half-life of F508-CFTR compared to wt-CFTR results from altered regulation of endocytic trafficking of F508-CFTR. To test this hypothesis we propose three specific aims: Specific Aim #1. Test the hypothesis that the short plasma membrane half-life of F508-CFTR compared to wt-CFTR results from altered endocytic trafficking (increased endocytosis and/or decreased endocytic recycling) of F508-CFTR. The goal of this specific aim is to determine whether the decreased plasma membrane half-life of F508-CFTR is caused by alterations in endocytosis and/or endocytic recycling of CFTR; Specific Aim #2. Test the hypothesis that Rab5a and Rab4 regulate endocytic trafficking of CFTR. The goals of this specific aim are to determine whether these proteins regulate the endocytic trafficking of CFTR and whether altered expression of Rab5a and Rab4 is responsible for the short plasma membrane half-life of F508-CFTR; Specific Aim #3. To characterize the interactions between Rab5a and Rab4 with CFTR. The goals of this specific aim are to determine if Rab5a and/or Rab4 interact directly with CFTR, whether the F508 mutation alters the binding affinities between the Rab5a and Rab4 and CFTR, and to identify the Rab5a and Rab4 interacting proteins that may regulate the endocytic trafficking of CFTR. We anticipate that these studies will elucidate the cellular mechanisms that control the plasma membrane half-life of F508-CFTR. Furthermore, we anticipate that understanding these mechanisms will lead to novel therapeutic strategies for CF and other common diseases that, similar to CF, result from abnormal regulation of protein trafficking.

Dr. Swiatecka-Urban will interact with and collaborate with Drs. Madden (Project 3) and O’Toole (Project 1). In addition, she will interact closely with the other Project PIs who use proteomic approaches and she will be a major user of the Proteomics Core. Dr. Swiatecka-Urban will also interact with Dr. Shi (Project 5) to determine the feasibility of applying the Geographic Imaging Systems approach to study the spatial relationship of subcellular structures in airway epithelial cells.

Dr. Swiatecka-Urban's mentor is George Langford, Ph.D., Department of Biological Sciences.