Article

Deficiency of ribosomal protein S19 during early embryogenesis leads to reduction of erythrocytes in a zebrafish model of Diamond-Blackfan anemia.

Frontier Science Research Center, University of Miyazaki, Miyazaki 889-1692, Japan.
Human Molecular Genetics (Impact Factor: 7.69). 10/2008; 17(20):3204-11. DOI: 10.1093/hmg/ddn216
Source: PubMed

ABSTRACT Ribosomes are responsible for protein synthesis in all cells. Ribosomal protein S19 (RPS19) is one of the 79 ribosomal proteins (RPs) in vertebrates. Heterozygous mutations in RPS19 have been identified in 25% of patients with Diamond-Blackfan anemia (DBA), but the relationship between RPS19 mutations and the pure red-cell aplasia of DBA is unclear. In this study, we developed an RPS19-deficient zebrafish by knocking down rps19 using a Morpholino antisense oligo. The RPS19-deficient animals showed a dramatic decrease in blood cells as well as deformities in the head and tail regions at early developmental stages. These phenotypes were rescued by injection of zebrafish rps19 mRNA, but not by injection of rps19 mRNAs with mutations that have been identified in DBA patients. Our results indicate that rps19 is essential for hematopoietic differentiation during early embryogenesis. The effects were specific to rps19, but knocking down the genes for three other RPs, rpl35, rpl35a and rplp2, produced similar phenotypes, suggesting that these genes might have a common function in zebrafish erythropoiesis. The RPS19-deficient zebrafish will provide a valuable tool for investigating the molecular mechanisms of DBA development in humans.

0 Bookmarks
 · 
69 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ribosomal proteins (RPs) have gained much attention for their extraribosomal functions particularly with respect to p53 regulation. To date, about fourteen RPs have shown to bind to MDM2 and regulate p53. Upon binding to MDM2, the RPs suppress MDM2 E3 ubiquitin ligase activity resulting in the stabilization and activation of p53. Of the RPs that bind to MDM2, RPL5 and RPL11 are the most studied and RPL11 appears to have the most significant role in p53 regulation. Considering that more than 17% of RP species have been shown to interact with MDM2, one of the questions remains unresolved is why so many RPs bind MDM2 and modulate p53. Genes encoding RPs are widely dispersed on different chromosomes in both mice and humans. As components of ribosome, RP expression is tightly regulated to meet the appropriate stoichiometric ratio between RPs and rRNAs. Once genomic instability (e.g. aneuploidy) occurs, transcriptional and translational changes due to change of DNA copy number can result in an imbalance in the expression of RPs including those that bind to MDM2. Such an imbalance in RP expression could lead to failure to assemble functional ribosomes resulting in ribosomal stress. We propose that RPs have evolved ability to regulate MDM2 in response to genomic instability as an additional layer of p53 regulation. Full understanding of the biological roles of RPs could potentially establish RPs as a novel class of therapeutic targets in human diseases such as cancer.
    Oncotarget 02/2014; · 6.64 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Diamond Blackfan anemia (DBA) is an inherited bone marrow failure syndrome. As with the other rare inherited bone marrow failure syndromes, the study of these disorders provides important insights into basic biology and, in the case of DBA, ribosome biology; the disruption of which characterizes the disorder. Thus DBA serves as a paradigm for translational medicine in which the efforts of clinicians to manage DBA have informed laboratory scientists who, in turn, have stimulated clinical researchers to utilize scientific discovery to provide improved care. In this review we describe the clinical syndrome Diamond Blackfan anemia and, in particular, we demonstrate how the study of DBA has allowed scientific inquiry to create opportunities for progress in its understanding and treatment.
    Expert Review of Hematology 03/2014; · 2.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ribosomal biogenesis involves processing of pre-rRNA in assembly with ribosomal proteins (RPs). Deficiency of some RPs impairs processing and causes Diamond Blackfan Anemia (DBA) associated with anemia, congenital malformations, and cancer. p53 mediates many features of DBA but the mechanism of p53 activation remains unclear. Another hallmark of DBA is upregulation of adenosine deaminase (ADA) suggesting changes in nucleotide metabolism. In RP-deficient zebrafish, we found activation of both nucleotide catabolism and biosynthesis consistent with the need to break and replace the faulty rRNA. We also found upregulation of dNTP synthesis, a typical response to replication stress and DNA damage. Both RP-deficient zebrafish and human hematopoietic cells showed activation of the ATR/ATM/CHK1/2/p53 pathway. Other features of RP deficiency included an imbalanced dNTP pool, ATP depletion, and AMPK activation. Replication stress and DNA damage in cultured cells in non-DBA models can be decreased by exogenous nucleosides. Therefore, we treated RP-deficient zebrafish embryos with exogenous nucleosides and observed decreased activation of p53 and AMPK, reduced apoptosis, and rescue of hematopoiesis. Our data suggest that DNA damage response contributes to p53 activation in cellular and zebrafish models of DBA. Furthermore, rescue of RP-deficient zebrafish with exogenous nucleosides suggests that nucleoside supplements may be beneficial in DBA.
    Disease Models and Mechanisms 05/2014; · 4.96 Impact Factor

Full-text

Download
0 Downloads