A molecular switch for Cdc48 activity and localization during oxidative stress and aging

The cellular redox status has long been linked to many different cellular functions and behaviors, including protein homeostasis and aging. Accordingly, the cell has developed highly regulated systems that contribute to the maintenance of both the global redox status and protein homeostasis, as correlated with aging. One of the major proteins involved in protein degradation is the essential and highly conserved protein Cdc48 (p97/VCP in mammals). Cdc48 serves as a shuttle bus of sorts, extracting and delivering misfolded proteins from the ER, mitochondria, nucleus, cytosol, etc. to the proteasome for degradation.

In this project, we define a crosstalk between redox regulation and protein homeostasis and quality control through the yeast Cdc48. Using a combination of redox proteomics, cell biology, and genetics, we discovered a potential regulatory site for Cdc48 activity and localization which affects growth and the cellular response to oxidative stress. Imaging reveals that mutation of this site also significantly alters Cdc48 localization, while proteomic analysis confirms changes in its interactome. This mutation further disrupts Cdc48’s redox regulation and interaction with the ER, as seen through the unfolded protein response (UPR), association with mitochondria, and lipid biogenesis pathways during aging. In addition, this project led to the development of a methodology based on in-vivo encoded redox sensors to identify changes to the cellular redox status and thus investigate native redox-dependent heterogeneity during chronological aging.