Ensuring that proteins acquire and maintain their proper conformation is essential as unfolded proteins not only are inactive but also tend to form toxic aggregates. The quality control of proteins is mediated by chaperones which help protein folding as well as proteases which degrade unfolded proteins. While protein quality control occurs at all time, it can be transcriptionally up-regulated in response to increased stress. This stress response, also called unfolded protein response (UPR), has been shown to exist in several cellular compartments, allowing the cell to respond to unfolded protein stress locally. While UPRs have been identified in the cytosol, the ER and the mitochondria, the existence of such a response in peroxisomes remains elusive.
Peroxisomes participate in several key biological processes (such as breakdown of fatty acids for energy production and degradation of toxic hydrogen peroxide). These organelles are essential as defects in their biogenesis have been associated with a group of fatal diseases, the Zellweger Syndrome Disorders. Understanding how quality control of peroxisomal proteins is achieved is therefore not only a very important basic biological question but it may also help to get a better understanding of these diseases. Using the model Caenorhabditis elegans and a combination of genetic and cell biological approaches, we want to understand how peroxisomes communicate with the nucleus in the context of peroxisomal protein quality control.
Peroxisomes in C. elegans hypodermal cells
visualized using a GFP::PTS1 reporter