Moises Chavez

Research Summary

Regulation of CFTR by Disabled-2 (Dab2). Cystic Fibrosis is a genetic disorder that is caused by a loss of function in cystic fibrosis trans-membrane conductance regulator (CFTR), a key chloride channel. CFTR is responsible for transporting chloride across the apical membrane of bronchial epithelial cells in order to maintain an airway surface liquid in the lungs. Functional loss of CFTR results in an extra-thick mucus environment in the lungs that prevents mucociliary clearance, thus promoting chronic bacterial infection. The Madden Lab investigates the regulation of CFTR in the model of Cystic Fibrosis. I am researching the interaction between CFTR and human Disabled-2 (Dab2), a clathrin-associated sorting protein. The CFTR:Dab2 interaction exemplifies a central aspect of the life cycle of membrane proteins: endocytic uptake. Previous research in the Madden lab, and others, demonstrates that the CFTR undergoes numerous rounds of clathrin-mediated endocytosis (CME), while maintaining a relatively long half-life. The Dab2 DAB Homology domain (Dab2DH) has been shown to be critical in an essential endocytic pathway, the assembly polypeptide-2 complex (AP-2) independent CME of CFTR. Dab2 functions to recruit CFTR to clathrin-coated vesicles, (CCV), as is demonstrated in a series of experiments of siRNA knockdown of Dab2 and AP-2 subunits that CFTR stability is increased in the former but not in the latter. Further, Dab2 confers preferential uptake of CFTR as inferred through a 10-fold knockdown of CCV that only decreases CFTR CCV recruitment 2-fold. I am interested in piercing the veil that is Dab2's stereospecific and functional role in CFTR's privileged cargo loading by developing acute small molecule inhibitors. These selective competitive inhibitors of the Dab2DH will help me to elucidate Dab2's role in CFTR cargo loading and endocytosis. By understanding the mechanisms of one adaptor protein, Dab2, in the context of CME of a membrane protein, CFTR, I hope to gain a strong understanding both of this specific mechanism, and a basis for investigating other adaptor and trafficking proteins.