CFTR Degradation and Aggregation

Defective protein folding is becoming increasingly recognized as a significant cause of human disease, and cystic fibrosis (CF) is a prime example. A number of CF-causing mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) result in a CFTR protein that does not reach the plasma membrane but is instead retained by the cellular quality control system and degraded by the ubiquitin-proteasome system. Misfolded CFTR that cannot be degraded accumulates in the cell as centrosome-associated inclusions of aggregated protein that are replete with proteasome components. In fact, the centrosomal region is a significant site of proteasome concentration in resting cells, suggesting a novel role for this subcellular location in the quality control of protein expression. This chapter gives an overview of CFTR misfolding, degradation, and aggregation, and provides details of methods used in our laboratory to study these processes.