During my career, I dedicated myself to the study of genetics, molecular biology and physiology of yeast, with particular interest on the defects of mitochondrial metabolism due to mutations in genes which are the cause of mitochondrial diseases in humans.
During my PhD course and my post-doc fellowship, both held at the University of Parma (Italy) under the supervision of Tiziana Lodi and Ileana Ferrero, I studied, with the help of molecular approaches, several aspects linked to replication of mitochondrial DNA (mtDNA) in yeast. My main interest concerned the creation of a yeast model system for the analysis of pathological mutations in the POLG gene, encoding the catalytic subunit of the mitochondrial DNA polymerase, whose mutations are associated to a wide range of mitochondrial disorders. Yeast was chosen because mtDNA replication apparatus is conserved between yeast and man and yeast can be easily manipulated thanks to the well-known techniques of molecular genetics and genetic engineering used in this organism.
This yeast model allowed me to study four main aspects linked to mutations in the yeast gene encoding for Polg, called MIP1:
1. validation of potentially pathological human mutations, i.e. evaluation, through study of the equivalent mutations in MIP1, of the effects of these mutations related to OXPHOS function and to extended and point mutability of mitochondrial DNA;
2. chemical rescue of the phenotype induced by MIP1 mutations, i.e. identification of molecules, in particular antioxidants, capable to reduce the effects on mitochondrial DNA instability induced by mutations;
3. genetic rescue of the pathological phenotype by means of overexpression of RNR1 gene, encoding the ribonucleotide reductase subunit R1;
4. understanding the molecular mechanisms underlying the pathology. This goal has been reached during the one-year stage at the FYSA Department in Louvain-la-Neuve (Belgium), under the supervision of Francoise Foury. There I studied the interactions between pathological MIP1 mutations located in cis or in trans and the molecular mechanisms of MIP1 mutations by means of measurement of mitochondrial protein levels and of in vitro polymerase activity of mutant variants of Mip1p.
In the last years, thanks to national and international collaborations, I studied mutations affecting genes involved in the modification/maturation of mitochondrial tRNAs, such as MTO1, encoding the mitochondrial tRNA uridine 5-carboxymethylaminomethylase, human ELAC2/yeast TRZ1, encoding the mitochondrial RNase Z, hTRIT1/yMOD5, encoding the A37 tRNA adenylate isopentenyltransferase, in the aminoacylation of mitochondrial tRNAs, such as hAARS2/yALA1 and hVARS2/yVAS1, encoding the mitochondrial alanyl-tRNA synthetase and valyl-tRNA synthetase, respectively, and hDNM1L,yDNM1, encoding a dynamin like protein involved in mitocjodnrial fission.
In 2013 Tiziana Lodi and me, toghether with our collaborators Agnes Delahodde, Laras Pitayu and Agnes Rotig from University of Paris-Sud (France), discovered, by the meaning of a high-throughput screening of FDA-approved drugs on yeast mip1 mutants, a molecule able to reduced the frequency of deletions in mtDNA for which a France patent has been filed and an EU patent is pending.
Since 2013, I’m working, as unit leader, on the study of pathological mutations in OPA1 in a proper yeast model constructed in our lab where human OPA1, unable by itself to complement the deletion in the yeast orthologous gene MGM1, was fused with a region of MGM1, leading to the construction of a functional chimera.