Project description:We employed a gene complementation strategy combined with microarray screening to identify miRNAs involved in the formation of erythroid (red blood) cells. To search for GATA-1-regulated erythroid miRNAs, we used the Gata-1– erythroblast line G1E. These cells proliferate in culture as immature erythroid precursors and undergo terminal maturation when GATA-1 activity is restored. G1E-ER4 is a sub-line stably expressing an estrogen-activated form of GATA-1 (GATA-1 fused to the ligand binding domain of the estrogen receptor). Treatment of G1E-ER4 cells with estradiol induces a GATA-1-regulated program of gene expression with concomitant cellular maturation. We used a microarray to evaluate the expression of 292 different miRNAs in G1E-ER4 cells at 0 versus 24 hours after GATA-1 activation. Affymetrix gene expression profiling has previously been deposited (GEO accession no. GSE628). Keywords: microRNA analysis of a cell-line model of erythroid maturation
Project description:The development and function of stem and progenitor cells that produce blood cells are vital in physiology. GATA2 mutations cause immunodeficiency, myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). GATA-2 physiological activities necessitate that it be strictly regulated and cell type-specific enhancers fulfill this role. The +9.5 intronic enhancer harbors multiple conserved cis-elements, and germline mutations of these cis-elements are pathogenic in humans. Since mechanisms underlying how GATA2 enhancer disease mutations impact hematopoiesis and pathology are unclear, we generated mouse models of the enhancer mutations. While a multi-motif mutant was embryonic lethal, a single-nucleotide Ets motif mutant was viable and steady-state hematopoiesis was normal. However, the Ets motif mutation abrogated stem/progenitor cell regeneration following stress. These results reveal a new mechanism in human genetics in which a disease mutation inactivates enhancer regenerative activity, while sparing developmental activity. Mutational sensitization to stress that instigates hematopoietic failure constitutes a paradigm for GATA-2-dependent pathogenesis.
