Identification and characterization of novel compounds that can alleviate mitochondrial dysfunction using yeast as a model

Mitochondrial dysfunction is related to various human pathologies including inborn errors of mitochondrial metabolism such as Lebers hereditary optic neuropathy, age-related neurodegenerative disorders such as Alzheimers disease and Parkinsons disease but also rare diseases such as Wilson disease and Niemann Pick disease type C1. In addition, mitochondrial dysfunction is not exclusively related to inborn/acquired mutations, but can also be caused by for instance drugs such as the chemotherapeutic agents cisplatin (Cp) or excess copper (Cu) as is the case for Wilson disease. Wilson disease is characterized by Cu accumulation in the liver, leading to acute liver failure or cirrhosis, but also causing neurodegeneration. Next to Cu-induced mitochondrial dysfunction, excess Cu is known to induce oxidative stress and apoptosis. In addition, mitochondrial dysfunction-related conditions are also often characterized by aberrancies in sphingolipid metabolism, a class of lipid species that are important membrane constituents, but also have crucial signaling roles in orchestrating a wide range of biological processes. Current treatment options for mitochondrial dysfunction-related disorders, however, are inadequate, emphasizing the need for novel treatment options. The major goal of this PhD was to identify and characterize novel compounds that can alleviate mitochondrial dysfunction upon treatment with excess Cu or Cp, thereby using the budding yeast Saccharomyces cerevisiae as a model eukaryote. To this end, we focused on the bioactive Arabidopsis thaliana-derived decapeptide OSIP108, which is characterized by anti-oxidant activity, and on a repositioning library (Pharmakon 1600 Repositioning library) that comprises 1600 off-patent drugs and bioactive agents. Such repositioned drugs are characterized by a well-known toxicity profile and mode of action of their primary aimed activity. This work shows that the OSIP108 peptide can prevent Cu-induced oxidative stress and apoptosis in yeast and human cells, and this effect is likely mediated by an effect on sphingolipid metabolism. Subsequently, we successfully translated these data to relevant in vitro and in vivo models applicable to Wilson disease. To this end we show that OSIP108 prevents Cu-induced cell death of human neuroglioblastoma cells and decreases Cu-induced changes in liver morphology (indicative for liver damage) of zebrafish larvae. Furthermore, we extrapolated our analysis of the bioactive properties of OSIP108 to Cp-induced toxicity, as we describe the protective effect of OSIP108 against Cp-induced toxicity in yeast and human cells, as well as a direct effect on basic cellular metabolism in human cells. Moreover, we describe the screening of the Pharmakon 1600 Repositioning library for agents that can prevent Cu-induced toxicity in yeast, resulting in the identification of the drug class of Angiotensin II Type 1 Receptor blockers. Moreover, in line with our research on OSIP108, we show that several Angiotensin II Type1 Receptor blockers can prevent Cu-induced toxicity in S. cerevisiae, as well as Cp-induced toxicity. In summary, the results of this PhD research indicate that OSIP108 and specific Angiotensin II Type 1 Receptor blockers show promise as therapeutic options in treatment of Wilson disease, or of mitochondrial dysfunction-related disorders in general. Furthermore, not only does our research shed light onto sphingolipids as a direct target in treatment of Wilson disease, knowledge of the pro-survival mode of action of OSIP108 and the Angiotensin II Type 1 Receptor blockers in S. cerevisiae will likely reveal putative novel therapeutic targets for treatment of human mitochondrial dysfunction-related disorders.

Jaar van publicatie:2014

Toegankelijkheid:Closed