Expression analysis of BM cells of ASXL-MT induced MDS mice

ABSTRACT: Recurrent mutations in ASXL1 are found in various hematological malignancies and are associated with poor prognosis. In particular, ASXL1 mutations are frequently found in patients with hematological malignancies associated with myelodysplasia including myelodysplastic syndromes (MDS), and chronic myelomonocytic leukemia. Although loss-of-function ASXL1 mutations promote myeloid transformation, a large subset of ASXL1 mutations is thought to result in stable truncation of ASXL1. Here we demonstrate that C-terminal truncating ASXL1 mutations (ASXL1-MT) inhibit myeloid differentiation and induce MDS-like disease in mice, displaying all the features of human MDS including multi-lineage myelodysplasia, pancytopenia and occasional progression to overt leukemia. Concerning the molecular mechanisms, ASXL1-MT derepressed expression of Hoxa9 and miR-125a through inhibiting PRC2-mediated methylation of H3K27. miR-125a targeted expression of a surface receptor Clec5a, which was found to supports for myeloid differentiation. In addition, HOXA9 expression was high in MDS patients with ASXL1 mutations while Clec5a expression was generally low in MDS patients. Thus, ASXL1-MT induced MDS-like disease in mice via derepression of Hoxa9 and miR-125a, and Clec5a downregulation. Our data provide evidence for a novel axis of MDS pathogenesis (ASXL1 mutations-upregulation of HoxA9 and miR-125a-downregulation of Clec5a) and implicate both ASXL1 mutants and miR-125a as therapeutic targets in MDS. BM cells derived from mock-transplanted mice and ASXL1-MT transplanted mice were incubated with biotinylated antibodies for CD3e, B220, and TER-119, followed by incubation with streptavidin Micro Beads (Miltenyi Biotec). The marker-negative fraction was separated with LS Columns (Miltenyi Biotec). Using the sorted-BM cells, we compared the expression proliles between 3 sorted-BM cells with mock and 3 sorted-BM cells with ASXL1-MT. Total RNA was extracted by Trizol reagent (Invitrogen) according to the manufacturer’s protocol. Double-stranded cDNA was synthesized from 5 μg of total RNA with oligo (dT)24 T7 primer, amplified with T7 RNA polymerase up to approximately 50 μg of cRNA, and hybridized to Affymetrix Mouse Expression array 430A, which contains 45000 probe sets for 39000 transcripts and variants from over 34000 well-characterized mouse genes (Affymetrix). After washing and staining, the arrays were scanned on the GeneChip system confocal scanner (Affymetrix). The intensity for each feature of the array was captured with Affymetrix Microarray Suite (MAS) Version 5.0 software. Gene set enrichment analysis was performed by using Gene Ontology gene sets from the Molecular Signatures Database (http://www.broad.mit.edu/gsea/msigdb/).

ORGANISM(S): Mus musculus

SUBMITTER: Daichi Inoue 

PROVIDER: E-GEOD-49118 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress