(a) Schematic drawing of two murine ADAR1 mRNA and protein species. ADAR1 p150 protein is encoded by an mRNA transcribed from an interferon-inducible promoter (Pi), and ADAR1 p110 protein is encoded by an mRNA transcribed from a constitutively active promoter (PC). Translation start sites (AUG) within transcripts are indicated. White boxes, 5’-untranslated region (UTR); thick black horizontal lines, regions amplified by real-time PCR, broken horizontal lines, 3’-UTR; dark-grey boxes, putative Z-DNA binding domains (α and β); black boxes, RNA binding domains (I-III); closed circles, conserved residues within deaminase domain. (b) Real-time PCR analysis of ADAR1 mRNA expression in ES cells (ESC), long-term (LKS+CD34lo) and short-term (LKS+CD34hi) HSCs, total HSCs (LKS+), and multipotent progenitors (LKS−) using oligonucleotides specific for the IFN-inducible ADAR1 p150 (dark grey bars) and the constitutive ADAR1 p110 (light grey bars) transcripts. ADAR1 mRNA expression was normalized to YWHAZ (GenBank™/EBI accession number 22631) mRNA expression using the ΔΔCt method. Data are expressed as mean ± s.d. (c) Gene set enrichment analysis of genome-wide transcriptome expression data from ADAR1−/− (KO) relative to control HSCs. Among 1247 curated gene sets (represented by green dots), those that were annotated as upregulated by interferon signaling are colored in red, whereas those downregulated by interferon signaling are represented by blue dots. Positive net enrichment scores denote gene sets that were upregulated in KO cells. Negative scores reflect downregulated gene sets. The yellow area contains significantly altered gene sets with a false-discovery rate (FDR) of <0.05. (d) Heat map of the most significantly deregulated genes (FDR<0.1), ranked by t test score. Red color reflects high expression, and blue color indicates low expression. Black dots label genes known to be inducible by interferons (IFN) α, β, or γ. (e) Validation of gene array data by quantitative PCR. The graph shows mRNA expression of representative genes normalized to YWHAZ mRNA expression in lineage-depleted CD150+CD48−CD244− (HSC) and CD150−CD48+ (MPP) cells from early-E11 wild-type (+/+), Adar+/− (+/−), and ADAR1-deficient (−/−) FL. Data are expressed as mean ± s.e.m. (2−6 samples per group). White column tops indicate statistically significant differences (p value < 0.03) between Adar−/− and control cells, as determined by unpaired t test. Names of known interferon-inducible genes are in red color.