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Research

Proteostasis in aging and neurodegenerative diseases

Our in vivo model systems: C. elegans and HeLa cells expressing HTTExon1Q97

C. elegans moving and feeding on a bacterial lawn.  C. elegans is completely transparent and is ideally suited to express fluorescently tagged proteins and to track the expression and aggregation of amyloid proteins or to measure turnover rates as depicted below using photo-convertible fluorophores.  The nematode has a lifespan of about 25 days and hence a great aging model to study late age of onset neurodegenerative diseases such as Alzheimer's and Huntington's disease.

We also employ cell culture models e.g. as depicted here HeLa cells that express HttExon1Q97-GFP that forms amyloid fibrils and can be visualized by fluorescence microscopy.  The video shows a collapsed z-stack and the Htt fibrils become visible as amyloid fibrils.  

Please, click on the videos to start them.

 

In addition, we study the amyloid fibrils formed by mutant Htt and Ab1-42 in vitro using FRET, AFM and EM. These in vitro analyses allow us to assess the effect of molecular chaperones to suppress the amyloid fibril formation or their capacity to disaggregate the fibrils. 

 

Photoconversion in vivo to measure the half-life time using the photo-convertible fluorophore Dendra-2

Phoconversion Dendra2 example
Depicted is Drebrin-Dendra-2 expressed in C.elegans before (left) and after (right) exposure to 405 nm that shifts the emission spectrum from the green to the red spectrum. The red moiety can be tracked over time to access the stability of the protein.

Confocal microscopy of neurons in the nematode C.elegans

Confocal microscopy of neurons of the nematode C. elegans
Analysis of neuronal proteins by fluorescent fusion proteins. Depicted in green is the actin-binding protein Drebrin and in red Abeta1-42 that is associated with Alzheimer disease.

Research goal

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.

Current Research

picture of FLIM to monitor protein aggregation in vivo
FLIM to monitor protein aggregation in vivo
Picture of EM analysis of Huntingtin fibils and chaperone binding
EM analysis of Huntingtin fibils and chaperone binding
HTT fibrils AFM
Atomic Force Microscopy (AFM) analysis of HTTExon1 fibrils