title: Functional study in a yeast model of a novel succinate dehydrogenase subunit B gene germline missense mutation (C191Y) diagnosed in a patient affected by a glomus tumor.
abstract: Mutations of succinate dehydrogenase (SDH) subunits B, C and D are associated to pheochromocytoma/paraganglioma (PGL) development. The mechanisms linking SDH mutations to tumorigenesis are currently unknown. We report a novel germline missense SDHB mutation (C191Y) in a patient affected by a glomus tumor. The missense mutation hits an amino acid residue conserved from mammals to the yeast Saccharomyces cerevisiae. The pathogenic significance of the human mutation was validated in a yeast model. SDH2(C184Y) mutant allele equivalent to human SDHB(C191Y) did not restore the OXPHOS phenotype of the Deltasdh2 null mutant. In the mutant, SDH activity was also abolished along with a reduction in respiration. Sensitivity to oxidative stress was increased in the mutant, as revealed by reduced growth in the presence of menadione. Remarkably, the frequency of petite colony formation was increased in the mutant yeast strain, indicating an increased mtDNA mutability. Histochemistry demonstrates that SDH activity was selectively absent in the patient tumor tissue. Overall, our results demonstrate that the C191Y SDHB mutation suppresses SDH enzyme activity leading to increased ROS formation and mtDNA mutability in our yeast model. These findings further our understanding of the mechanisms underlying PGL development and point to the yeast model as a valid tool to investigate on the possible pathogenic relevance of SDH novel mutations and/or rare polymorphism.
authors.affiliation: Department of Genetics, Biology of Microorganisms, Anthropology and Evolution, University of Parma, Parma, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Goffrini
authors.forename: Tonino
authors.initials: T
authors.lastname: Ercolino
authors.forename: Elena
authors.initials: E
authors.lastname: Panizza
authors.forename: Valentino
authors.initials: V
authors.lastname: Giachè
authors.forename: Leonardo
authors.initials: L
authors.lastname: Cavone
authors.forename: Alberto
authors.initials: A
authors.lastname: Chiarugi
authors.forename: Veronica
authors.initials: V
authors.lastname: Dima
authors.forename: Iliana
authors.initials: I
authors.lastname: Ferrero
authors.forename: Massimo
authors.initials: M
authors.lastname: Mannelli
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D004252:DNA Mutational Analysis; D005260:Female; D018095:Germ-Line Mutation; D005918:Glomus Tumor / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D018384:Oxidative Stress; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013385:Succinate Dehydrogenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: C541941:SDH2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C108095:SDHB protein, human; D013385:Succinate Dehydrogenase