Publication Date:
2011-11-18
Description:
Abstract 550 Lysine specific demethylase 1 (LSD1) is a demethylase that acts on mono- and dimethylated H3K4 (H3K4me1/2). Consistent with H3K4me2 (an active marker of transcription) as a substrate, LSD1 is part of a core complex with the co-repressor, CoREST and HDAC1/2. Previously our lab demonstrated that regulation of hematopoietic differentiation depends in part on the interaction of the growth factor independent transcription factors (= Gfi1 and Gfi1b) with the LSD1/CoREST/HDAC complex. We generated a conditional knock out mouse for LSD1 (LSD1fl/fl) to study its roles in hematopoiesis. Inducible deletion of LSD1fl/fl mice in all hematopoietic lineages with Mx-Cre resulted in severe neutropenia. Flow cytometric analysis showed that LSD1fl/fl Mx-Cre mice lacked Gr-1high Mac-1high double positive mature neutrophilic granulocytes in the bone marrow and the peripheral blood; however, the frequency of Gr-1dim Mac-1high (mainly consisting of promyelocytes and myeloblasts but not mature neutrophils) increased in frequency. To reveal the mechanism responsible for the observed neutropenia, we performed global mRNA expression profiling and chromatin immunoprecipitation sequencing (ChIPSeq) for H3K4 methylation states in Gr-1dim Mac-1high cells from LSD1fl/fl Mx-Cre and LSD1fl/fl mice. Five hundred ninety-eight genes (412 up / 186 down; p≤0.01, 2-fold cutoff) were differentially expressed in the absence of LSD1. Although we did not detect changes in expression of established myeloid transcription factors, including Pu.1, C/EBPα, C/EBPε or Gfi1, gene set enrichment analysis (GSEA) of Gr-1dim Mac-1high cells from LSD1fl/fl Mx-Cre using gene signatures for mature myeloid cells clearly showed that LSD1 deficient Gr-1dim Mac-1high cells failed to display a gene signature of differentiated myeloid cells (NES: 1.88; p≤0.003). Among the most highly upregulated genes, we observed genes highly expressed in hematopoietic stem and progenitor cells (HSPCs; i.e.: CD34 36.2-fold; HoxA9 26.3-fold; Sca-1 10.8-fold; Meis 1 2.6-fold). Therefore we performed GSEA using signatures from HSPCs (encompassing over 200 genes); the stem/progenitor gene set was highly significantly enriched (NES: −1.9; p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
Permalink