title: SBDS-Deficient Cells Have an Altered Homeostatic Equilibrium due to Translational Inefficiency Which Explains their Reduced Fitness and Provides a Logical Framework for Intervention.
abstract: Ribosomopathies are a family of inherited disorders caused by mutations in genes necessary for ribosomal function. Shwachman-Diamond Bodian Syndrome (SDS) is an autosomal recessive disease caused, in most patients, by mutations of the SBDS gene. SBDS is a protein required for the maturation of 60S ribosomes. SDS patients present exocrine pancreatic insufficiency, neutropenia, chronic infections, and skeletal abnormalities. Later in life, patients are prone to myelodisplastic syndrome and acute myeloid leukemia (AML). It is unknown why patients develop AML and which cellular alterations are directly due to the loss of the SBDS protein. Here we derived mouse embryonic fibroblast lines from an SbdsR126T/R126T mouse model. After their immortalization, we reconstituted them by adding wild type Sbds. We then performed a comprehensive analysis of cellular functions including colony formation, translational and transcriptional RNA-seq, stress and drug sensitivity. We show that: 1. Mutant Sbds causes a reduction in cellular clonogenic capability and oncogene-induced transformation. 2. Mutant Sbds causes a marked increase in immature 60S subunits, limited impact on mRNA specific initiation of translation, but reduced global protein synthesis capability. 3. Chronic loss of SBDS activity leads to a rewiring of gene expression with reduced ribosomal capability, but increased lysosomal and catabolic activity. 4. Consistently with the gene signature, we found that SBDS loss causes a reduction in ATP and lactate levels, and increased susceptibility to DNA damage. Combining our data, we conclude that a cell-specific fragile phenotype occurs when SBDS protein drops below a threshold level, and propose a new interpretation of the disease.
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.
authors.forename: Piera
authors.identifier: 0000-0002-3780-1050
authors.initials: P
authors.lastname: Calamita
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.
authors.forename: Annarita
authors.initials: A
authors.lastname: Miluzio
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.|DiSIT, University of Eastern Piedmont, Alessandria, Italy.
authors.forename: Arianna
authors.initials: A
authors.lastname: Russo
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.
authors.forename: Elisa
authors.identifier: 0000-0003-4214-1904
authors.initials: E
authors.lastname: Pesce
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Ricciardi
authors.affiliation: School of Biosciences, University of Birmingham Edgbaston Birmingham, United Kingdom.
authors.forename: Farhat
authors.initials: F
authors.lastname: Khanim
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Cheroni
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Alfieri
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.
authors.forename: Marilena
authors.initials: M
authors.lastname: Mancino
authors.affiliation: Campbell Family Institute for Breast Cancer Research, University Health Network, Toronto, Ontario, Canada.|Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
authors.forename: Chiara
authors.initials: C
authors.lastname: Gorrini
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.
authors.forename: Grazisa
authors.identifier: 0000-0001-6361-311X
authors.initials: G
authors.lastname: Rossetti
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM)-Fondazione Telethon, Pozzuoli, Italy.
authors.forename: Ivana
authors.initials: I
authors.lastname: Peluso
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.|Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Pagani
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM)-Fondazione Telethon, Pozzuoli, Italy.
authors.forename: Diego L
authors.initials: DL
authors.lastname: Medina
authors.affiliation: SickKids Children Hospital, Toronto, Ontario, Canada.
authors.forename: Johanna
authors.identifier: 0000-0001-8732-825X
authors.initials: J
authors.lastname: Rommens
authors.affiliation: INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.|DBS, Università degli Studi di Milano, Milan, Italy.
authors.forename: Stefano
authors.identifier: 0000-0002-3780-1050
authors.initials: S
authors.lastname: Biffo
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D004249:DNA Damage; D005347:Fibroblasts / Q000378:metabolism; D006706:Homeostasis; D019344:Lactic Acid / Q000378:metabolism; D051379:Mice; D010641:Phenotype; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D054683:Ribosome Subunits, Large, Eukaryotic / Q000235:genetics* / Q000378:metabolism
chemical_list: D011506:Proteins; D012333:RNA, Messenger; C513661:Sbds protein, mouse; D019344:Lactic Acid; D000255:Adenosine Triphosphate