Loss of ASXL1 triggers an apoptotic response in human hematopoietic stem and progenitor cells.
ASXL1 is frequently mutated in myelodysplastic syndrome and other hematological malignancies. It has been reported that a loss of ASXL1 leads to a reduction of H3K27me3 via the polycomb repressive complex 2 (PRC2). To determine the role of ASXL1 loss in normal hematopoietic stem and progenitor cells, cord blood CD34+cells were transduced with independent small hairpin interfering RNA lentiviral vectors against ASXL1 and cultured under myeloid and erythroid permissive conditions. Knockdown of ASXL1 led to a significant reduction in stem-cell frequency and a reduced cell expansion along the myeloid lineage. Cell expansion along the erythroid lineage was also reduced significantly and was accompanied by an increase in apoptosis of erythroid progenitor cells throughout differentiation and by an accumulation of cells in the G0/G1phase. Bone marrow stromal cells supported the growth of immature erythroid cells, but did not alter the adverse phenotype of ASXL1 knockdown. Chromatin immunoprecipitation revealed no loss of H3K27me3 in myeloid progenitor cells, but demonstrated a loss of H3K27me3 on the HOXA and the p21 locus in erythroid progenitors. We conclude that ASXL1 is essential for erythroid development and differentiation and that the aberrant differentiation is, at least in part, facilitated via PRC2.
Department of Experimental Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Susan
S
Hilgendorf
Department of Experimental Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Hendrik
H
Folkerts
Department of Experimental Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Jan Jacob
JJ
Schuringa
Department of Experimental Hematology, Cancer Research Center Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. Electronic address: e.vellenga@umcg.nl.
Edo
E
Vellenga
D018952:Antigens, CD34 / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics*; D015415:Biomarkers; D002450:Cell Communication; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D015672:Erythroid Precursor Cells / Q000378:metabolism; D017353:Gene Deletion; D055785:Gene Knockdown Techniques; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism; D023461:Myeloid Progenitor Cells / Q000166:cytology / Q000378:metabolism; D012097:Repressor Proteins / Q000172:deficiency* / Q000235:genetics
C473949:ASXL1 protein, human; D018952:Antigens, CD34; D015415:Biomarkers; D006657:Histones; D012097:Repressor Proteins