title: Missense mutations associated with Diamond-Blackfan anemia affect the assembly of ribosomal protein S19 into the ribosome.
abstract: RPS19 has been identified as the first gene associated with Diamond-Blackfan anemia (DBA), a rare congenital hypoplastic anemia that includes variable physical malformations. It is mutated in approximately 25% of the patients although doubts remain as to whether DBA clinical phenotype depends on the ribosomal function of RPS19 or on an extra-ribosomal role or on both. RPS19 mRNAs with mutations that introduce premature stop codons or eliminate it are rapidly turned over by the surveillance mechanisms possibly causing a decrease in the RPS19 protein level. A decrease in RPS19 level has been shown to cause a defect in the maturation of 18S ribosomal RNA. Less clear is the effect of missense mutations in RPS19. With the aim of analyzing the functional features of mutated RPS19, we prepared cDNA constructs expressing RPS19 containing 11 missense mutations and a trinucleotide insertion found in DBA patients. After transfection, we analyzed the following properties of the mutated proteins: (i) protein stability, (ii) subcellular localization and (iii) assembly into ribosomes. Our results indicate that some RPS19 mutations alter the capacity of the protein to localize in nucleolar structure and these mutated RPS19 are very unstable. Moreover, none of the mutated RPS19 analyzed in this study, including those proteins that appear localized into the nucleolus, is able to be assembled into mature ribosome.
authors.affiliation: Department of Biology, University 'Tor Vergata', Roma, Italy 00133.
authors.forename: Mara
authors.initials: M
authors.lastname: Angelini
authors.forename: Stefano
authors.initials: S
authors.lastname: Cannata
authors.forename: Valentina
authors.initials: V
authors.lastname: Mercaldo
authors.forename: Luisa
authors.initials: L
authors.lastname: Gibello
authors.forename: Claudio
authors.initials: C
authors.lastname: Santoro
authors.forename: Irma
authors.initials: I
authors.lastname: Dianzani
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Loreni
mesh_terms: D029503:Anemia, Diamond-Blackfan / Q000235:genetics*; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D018076:DNA, Complementary / Q000378:metabolism; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008954:Models, Biological; D009154:Mutation; D020125:Mutation, Missense; D011506:Proteins / Q000737:chemistry; D012269:Ribosomal Proteins / Q000235:genetics*; D012270:Ribosomes / Q000378:metabolism*; D013347:Subcellular Fractions; D013395:Sucrose / Q000494:pharmacology
chemical_list: D018076:DNA, Complementary; D011506:Proteins; D012269:Ribosomal Proteins; C040343:ribosomal protein S19; D013395:Sucrose