Knockdown of Hspa9, a del(5q31.2) gene, results in a decrease in hematopoietic progenitors in mice.
Heterozygous deletions spanning chromosome 5q31.2 occur frequently in the myelodysplastic syndromes (MDS) and are highly associated with progression to acute myeloid leukemia (AML) when p53 is mutated. Mutagenesis screens in zebrafish and mice identified Hspa9 as a del(5q31.2) candidate gene that may contribute to MDS and AML pathogenesis, respectively. To test whether HSPA9 haploinsufficiency recapitulates the features of ineffective hematopoiesis observed in MDS, we knocked down the expression of HSPA9 in primary human hematopoietic cells and in a murine bone marrow-transplantation model using lentivirally mediated gene silencing. Knockdown of HSPA9 in human cells significantly delayed the maturation of erythroid precursors, but not myeloid or megakaryocytic precursors, and suppressed cell growth by 6-fold secondary to an increase in apoptosis and a decrease in the cycling of cells compared with control cells. Erythroid precursors, B lymphocytes, and the bone marrow progenitors c-kit(+)/lineage(-)/Sca-1(+) (KLS) and megakaryocyte/erythrocyte progenitor (MEP) were significantly reduced in a murine Hspa9-knockdown model. These abnormalities suggest that cooperating gene mutations are necessary for del(5q31.2) MDS cells to gain clonal dominance in the bone marrow. Our results demonstrate that Hspa9 haploinsufficiency alters the hematopoietic progenitor pool in mice and contributes to abnormal hematopoiesis.
Department of Medicine, Division of Oncology, Washington University School of Medicine, 660 South Euclid Ave., St Louis, MO 63110, USA.
Tim H-P
TH
Chen
Amal
A
Kambal
Kilannin
K
Krysiak
Mark A
MA
Walshauser
Gagan
G
Raju
Justin F
JF
Tibbitts
Matthew J
MJ
Walter
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000502:physiology*; D002478:Cells, Cultured; D002872:Chromosome Deletion; D033481:Chromosomes, Mammalian / Q000235:genetics*; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism; D005434:Flow Cytometry; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D057895:Haploinsufficiency; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000473:pathology*; D006413:Hematopoietic System / Q000502:physiology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009190:Myelodysplastic Syndromes / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000502:physiology
D002352:Carrier Proteins; D018840:HSP70 Heat-Shock Proteins; C083794:Hspa9 protein, mouse; D016159:Tumor Suppressor Protein p53