Proteostasis in Aging and Disease (Janine Kirstein)

Utilizing a roGFP based folding sensor to access the redox status (green) in a nematode that is challenged with the expression of an aggregation-prone polyglutamine stretch (red) in muscle cells.

Research Overview

Our research goal is to advance our understanding of the mechanisms to maintain a functional proteome during the lifespan of a metazoan. We use a model organism that has a long-standing history as an excellent genetic model and more recently cell biology tools became available. However, any biochemical or biophysical studies were few and far in between in the literature of C. elegans research. On the other hand our understanding of chaperones and proteolytic machines, how they work, how they recognize a substrate and contribute to protein folding, are almost entirely based on in vitro or ex vivo data. Our research approach will bridge this gap and provide with C. elegans an excellent model utilizing biochemical, cell biology and genetic techniques addressing important biological questions on the management of protein misfolding and aggregation in a metazoan in vivo.

Specifically, we employ novel proteostasis sensors to analyze the chaperone and proteolytic capacity of distinct tissues and the whole organism during development and aging and upon chronic stress conditions in vivo in real-time. This extensive analysis will allow for an identification of the key chaperone and proteolytic complexes maintaining protein quality control and their interplay upon imbalance of proteostasis during aging and in neurodegenerative disease models (Huntington’s disease, Alzheimer’s disease, Parkinson’s disease etc.).

Our research will use a variety of complementary model systems. In addition to C. elegans we will also utilize mammalian cell tissue culture models as well as biochemical and biophysical in vitro techniques to gain mechanistic insight into the proteostasis network maintaining a healthy and functional proteome.

On the left: Luciferase-GFP as protein folding sensor. Luciferase is a meta-stable protein and requires the attention of molecular chaperone for its correct fold and function. A fusion to GFP allows for a visual read-out of its aggregation propensity in vivo. On the right: Luciferase-GFP (green) expressed in neurons of C. elegans reports on the chaperone capacity during neuronal aging. Shown here is the head region of the nematode and phalloidin (red) is used as a co-stain for muscle cells.
This cartoon summarizes our most recent findings of the relationship between proteostasis and redox homeostasis (Kirstein et al., 2015 EMBO J). Here we could demonstrate that imbalances of protein folding conditions provoked by the expression of amyloidogenic proteins, inhibition of the proteasome or aging trigger a loss of redox control in the ER and the cytosol. Whereas the cytosolic redox state changes from reducing towards oxidizing conditions, the ER shifts the opposite way and becomes reducing during aging and in response to proteotoxic challenges. This has detrimental consequences for the physiology of the cell and proteins of the secretory path.

Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP)
Campus Berlin-Buch
Robert-Roessle-Str. 10
13125 Berlin, Germany
+4930 94793 - 100 
+4930 94793 - 109 (Fax)

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