Karin Hochrainer

Post-translational protein modifications (PTMs) essentially contribute to the complexity of a cell’s proteome, giving rise to more than 1,000,000 functionally different proteins from about 100,000 transcripts. PTMs are important modulators of protein function under physiological conditions, but become even more important under stress, when they are heavily regulated to adapt the cellular proteome to the arising challenges. Consequently, PTMs affect countless cellular pathways and play an important role in disease development and combat. Neurodegeneration research is mainly focused on PTMs impact on protein aggregation. The Hochrainer Lab is looking at other, novel ways by which PTMs influence brain cell function in neurological diseases, such as ischemic stroke and tauopathy. 

One line of research in the Hochrainer Lab focuses on the role of ubiquitination, a PTM with the small molecule ubiquitin known for its potent effect on cell survival, in ischemic stroke. They found that ubiquitination is highly induced by ischemia, but how this impacts post-ischemic protein function and in particular neuronal survival has yet to be discovered. To shed light on this, the Lab is currently identifying post-ischemic ubiquitination targets, which appear to be enriched at the postsynaptic density (PSD) of neurons and bear kinase activity. The Lab is also working on identifying strategies to modify the heightened ubiquitination response after ischemia, with focus on deubiquitinase inhibition. 

In another line of research, the Hochrainer Lab investigates the role of pathogenic Tau in synaptic function, which they believe involves dysregulated palmitoylation, a lipid-based PTM. The microtubule-associated protein Tau is mainly found in axons, but in tauopathies, such as in Alzheimer’s Disease and frontotemporal dementia, travels to dendrites, where it causes synaptic dysfunction. In collaboration with Iadecola and Park Labs, they found that synaptic Tau disrupts an important signaling complex at the PSD, which is responsible for the production of nitric oxide, an agent involved in critical brain functions. The goal of this research is to find ways to restore the complex in tauopathy as a therapeutic intervention.