ABSTRACT
We identified a subset of genes involved in chromatin remodeling whose mRNA expression changes in differentiating mouse erythroleukemia (MEL) cells. We furthermore tested their mRNA expression patterns in normal and malignant CD34+ bone marrow cells. SMARCA5, imitation switch gene homologue, was rapidly silenced during in vitro erythroid differentiation of MEL cells whereas it was up-regulated in CD34+ hematopoietic progenitors of acute myeloid leukemia (AML) patients. Moreover, SMARCA5 mRNA levels decreased in AML CD34+ progenitors after the patients achieved complete hematologic remission. We detected high levels of SMARCA5 mRNA in murine bone marrow and spleen and monitored its expression in these hematopoietic tissues during accelerated hematopoiesis following hemolytic anemia induced by phenylhydrazine. SMARCA5 expression levels decreased after the onset of accelerated erythropoiesis. Our data suggest that both in vitro and in vivo induction of differentiation is followed by down-regulation of SMARCA5 expression. In CD34+ AML progenitors over-expression of SMARCA5 may thus dysregulate the genetic program required for normal differentiation.
Subject(s)
Chromatin/metabolism , Gene Expression Regulation, Leukemic , Hematopoiesis/genetics , Hematopoietic Stem Cells/metabolism , Leukemia, Myeloid/genetics , Neoplasm Proteins/genetics , Neoplastic Stem Cells/metabolism , Acute Disease , Anemia, Hemolytic/chemically induced , Anemia, Hemolytic/metabolism , Anemia, Hemolytic/pathology , Animals , Bone Marrow/metabolism , Bone Marrow/pathology , Cell Differentiation/drug effects , Cell Differentiation/genetics , DNA Topoisomerases, Type II/biosynthesis , DNA Topoisomerases, Type II/genetics , Erythroid Precursor Cells/metabolism , Erythroid Precursor Cells/pathology , Gene Expression Profiling , Hematopoietic Stem Cells/pathology , High Mobility Group Proteins/biosynthesis , High Mobility Group Proteins/genetics , Humans , Leukemia, Erythroblastic, Acute/genetics , Leukemia, Erythroblastic, Acute/metabolism , Leukemia, Erythroblastic, Acute/pathology , Leukemia, Myeloid/metabolism , Leukemia, Myeloid/pathology , Mice , Mice, Inbred C3H , Neoplasm Proteins/biosynthesis , Neoplastic Stem Cells/pathology , Phenylhydrazines/toxicity , RNA, Messenger/biosynthesis , RNA, Neoplasm/biosynthesis , Spleen/metabolism , Spleen/pathology , Subtraction Technique , Tumor Cells, CulturedABSTRACT
Diamond-Blackfan anemia (DBA) is a rare congenital pure red cell hypoplasia characterized by a selective defect of erythropoiesis with a normochromic macrocytic anemia and reticulocytopenia often accompanied by various congenital anomalies. The critical region responsible for the pathogenesis of DBA has been mapped in some patients to chromosome 19q13.2 (P Gustavsson, E Garelli, N Draptchinskaia, et al. Am. J. Hum. Genet. 63:1388-1395, 1998) and the gene encoding ribosomal protein S19 (RPS19) is believed to be the candidate gene. Here we present molecular analysis of the RPS19 gene in DBA patients from the Czech National DBA Registry. We found that the RPS19 gene was mutated in 25% (5/20) of DBA patients (insertion, deletion, and point mutations, but no nonsense or splice site mutations). Point mutations were localized to hot spots defined by Willig (TN Willig, N Draptchinskaia, I Dianzani, et al. Blood 94:4294-4306, 1999). Moreover, we describe two processed RPS19 pseudogenes, which were not expressed. Possible models of the DBA pathogenesis in the view of RPS19 mutations are discussed.
