Phd in CELL AND DEVELOPMENTAL BIOLOGY

Thesis title: Study of molecules of pharmaceutical interest on mitochondrial functionality in S. cerevisiae

The Cop9 Signalosome complex (CSN) plays a key role in many cellular processes, including the modulation of transcription of genes involved in ergosterol biosynthesis. Saccharomyces cerevisiae is an excellent model for the study of this complex and its catalytic subunit, Csn5. Our interest is mainly focused on the role of the Csn5 enzyme in ergosterol biosynthesis and its relationship with mitochondrial respiration. By studying the drugs that act on the biosynthesis of cholesterol / ergosterol, we first evaluated the effects of statins on yeast cells. The 3-hydroxy-3methylglutaryl-CoA (HMG-CoA) reductase enzyme is the key enzyme in cholesterol production and it is also the target of action of statins. By inhibiting this enzyme, statins block the production of cholesterol in the cell. We demonstrated that statins are active in S. cerevisiae, as they lower ergosterol levels also in yeast cell, and that statin treatment causes the loss of mitochondrial DNA. Previously, we identified two inhibitors of the Csn5 enzyme, and our study has shown that these inhibitors are active in reducing the levels of ergosterol in the cell. However, the low ergosterol levels induced by the treatment with inhibitors doesn’t result in mitochondrial damages or in a loss of mitochondrial DNA, since the mechanism of action is different from that of the statins. In the second part of my thesis, in collaboration with the group of prof. Tata, we tested the Csn5 inhibitors on immortalized glioblastoma cell lines; preliminary data showed that the action of the molecules has an influence on cell viability. As part of a broader collaboration between our laboratories, we have used the yeast S. cerevisiae to test two molecules synthesised and studied by Prof. Ada Maria Tata's group (Guerriero et al., 2021). The molecules Arecaidine Propargyl Ester (APE) and N8-Iper, designed as M2 muscarinic receptor agonists, influence tumour cell viability; in particular, N8-Iper causes an abnormal mitochondrial phenotype in glioblastoma cells. These molecules were then tested in yeast cells to verify if N8-Iper had a direct effect on mitochondrial function. The data show that N8-Iper causes alterations in mitochondrial function in yeast.