Interactions between RPS19, mutated in Diamond-Blackfan anemia, and the PIM-1 oncoprotein.
OBJECTIVE
Diamond Blackfan anemia (DBA) is a congenital disease characterized by defective erythroid progenitor maturation. Patients' bone marrow progenitor cells do not respond to erythropoietic growth factors, such as erythropoietin. Mutations in the gene encoding for ribosomal protein (RP) S19 account for 25% of cases of DBA. The link between defective erythropoiesis and RPS19 is still unclear. Two not mutually exclusive hypotheses have been proposed: altered protein synthesis and loss of unknown extraribosomal functions.


METHODS
We used yeast two-hybrid screening and a human liver cDNA library obtained at 19-24 weeks of gestation, when hepatic erythropoiesis is efficient, to search for proteins interacting with RPS19.


RESULTS
We found that RPS19 binds PIM-1, an ubiquitous serine-threonine kinase whose expression can be induced in erythropoietic cells by several growth factors, such as erythropoietin. The PIM-1/RPS19 interaction was demonstrated both in vitro and in living cells and led to phosphorylation of RPS19 in an in vitro kinase assay. We also showed that in human 293T cells PIM-1 interacts with ribosomes and may be involved in translational control. Three DBA-associated RPS19 mutations alter the binding between RPS19 and PIM-1.


CONCLUSIONS
A link between erythropoietic growth factor signaling and RPS19 has been identified for the first time.
Chiocchetti
Annalisa
A
IRCAD, Dipartimento di Scienze Mediche, Università del Piemonte Orientale, Novara, Italy.
Gibello
Luisa
L
Carando
Adriana
A
Aspesi
Anna
A
Secco
Paola
P
Garelli
Emanuela
E
Loreni
Fabrizio
F
Angelini
Mara
M
Biava
Alessandra
A
Dahl
Niklas
N
Dianzani
Umberto
U
Ramenghi
Ugo
U
Santoro
Claudio
C
Dianzani
Irma
I
D000595:Amino Acid Sequence / Q000502:physiology; D029503:Anemia, Diamond-Blackfan / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D004920:Erythropoiesis / Q000502:physiology; D015723:Gene Library; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding / Q000502:physiology; D025941:Protein Interaction Mapping; D051573:Proto-Oncogene Proteins c-pim-1 / Q000235:genetics / Q000378:metabolism*; D011817:Rabbits; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D015003:Yeasts
D012269:Ribosomal Proteins; C040343:ribosomal protein S19; C496634:PIM1 protein, human; D051573:Proto-Oncogene Proteins c-pim-1