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TISSUE-SPECIFIC STEM CELLS

Ribosomal Protein S19 Deficiency Leads to Reduced Proliferation and Increased Apoptosis but Does Not Affect Terminal Erythroid Differentiation in a Cell Line Model of Diamond-Blackfan Anemia

^aMolecular Medicine and Gene Therapy, Lund University, Lund, Sweden;
^bDepartment of Biochemistry and Molecular Biology, Nippon Medical School, Tokyo, Japan;
^cClinic for Internal Medicine C, Department of Hematology and Oncology, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany;
^dDepartment of Safety Research on Blood and Biologics, National Institute of Infectious Diseases, Tokyo, Japan

Key Words. Anemia • Apoptosis • Erythropoiesis • Lentiviral vector

Correspondence: Stefan Karlsson, M.D., Ph.D., Molecular Medicine and Gene Therapy, Lund University, BMC A12, 221 84, Lund, Sweden. Telephone: 46-222-05-77; Fax: 46-222-05-78; e-mail: stefan.karlsson{at}med.lu.se

Received July 18, 2007; accepted for publication October 22, 2007.
First published online in STEM CELLS EXPRESS   October 25, 2007.



Diamond-Blackfan anemia (DBA) is a congenital red-cell aplasia in which 25% of the patients have a mutation in the ribosomal protein (RP) S19 gene. It is not known how the RPS19 deficiency impairs erythropoiesis and proliferation of hematopoietic progenitors. To elucidate molecular mechanisms in RPS19-deficient DBA, we analyzed the effects of RPS19 deficiency on erythropoietin (EPO)-induced signal transduction, cell cycle, and apoptosis in RPS19-deficient TF-1 cells. We did not find any abnormality in EPO-induced signal transduction. However, RPS19-deficient TF-1 cells showed G0/G1 arrest (82% vs. 58%; p < .05) together with accumulation of p21 and p27. The fraction of apoptotic cells detected by Annexin V analysis also increased compared with control cells (13% vs. 3.1%; p < .05). Western blot analysis of apoptosis-related proteins showed that the level of bcl-2 and Bad was decreased and Bax was increased in RPS19-deficient TF-1 cells. Moreover, primary CD34-positive cells from DBA patients detected by Annexin V analysis also generated a higher number of apoptotic cells compared with normal CD34-positive cells during in vitro culture (38% vs. 8.9%; n = 5; p < .001). Finally, we show that although RPS19 silencing reduces EPO-induced development of erythroid progenitors expressing glycophorin A (GPA), RPS19 silencing in cells already expressing GPA does not affect GPA expression. These findings indicate that RPS19 deficiency causes apoptosis and accelerated loss of erythroid progenitors in RPS19-deficient DBA.

Disclosure of potential conflicts of interest is found at the end of this article.