Ets-dependent regulation of target gene expression during megakaryopoiesis.
Megakaryopoiesis is the process by which hematopoietic stem cells in the bone marrow differentiate into mature megakaryocytes. The expression of megakaryocytic genes during megakaryopoiesis is controlled by specific transcription factors. Fli-1 and GATA-1 transcription factors are required for development of megakaryocytes and promoter analysis has defined in vitro functional binding sites for these factors in several megakaryocytic genes, including GPIIb, GPIX, and C-MPL. Herein, we utilize chromatin immunoprecipitation to examine the presence of Ets-1, Fli-1, and GATA-1 on these promoters in vivo. Fli-1 and Ets-1 occupy the promoters of GPIIb, GPIX, and C-MPL genes in both Meg-01 and CMK11-5 cells. Whereas GPIIb is expressed in both Meg-01 and CMK11-5 cells, GPIX and C-MPL are only expressed in the more differentiated CMK11-5 cells. Thus, in vivo occupancy by an Ets factor is not sufficient to promote transcription of some megakaryocytic genes. GATA-1 and Fli-1 are both expressed in CMK11-5 cells and co-occupy the GPIX and C-MPL promoters. Transcription of all three megakaryocytic genes is correlated with the presence of acetylated histone H3 and phosphorylated RNA polymerase II on their promoters. We also show that exogenous expression of GATA-1 in Meg-01 cells leads to the expression of endogenous c-mpl and gpIX mRNA. Whereas GPIIb, GPIX, and C-MPL are direct target genes for Fli-1, both Fli-1 and GATA-1 are required for formation of an active transcriptional complex on the C-MPL and GPIX promoters in vivo. In contrast, GPIIb expression appears to be independent of GATA-1 in Meg-01 cells.
Department of Pathology and Laboratory Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina 29403, USA.
Pascale
P
Jackers
Gabor
G
Szalai
Omar
O
Moussa
Dennis K
DK
Watson
D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; D005786:Gene Expression Regulation; D005819:Genetic Markers; D006801:Humans; D039421:Integrin alpha2; D008533:Megakaryocytes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics; D009363:Neoplasm Proteins / Q000235:genetics; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000235:genetics; D011401:Promoter Regions, Genetic; D050784:Proto-Oncogene Protein c-ets-1; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D018121:Receptors, Cytokine / Q000235:genetics; D053628:Receptors, Thrombopoietin; D034061:Thrombopoiesis / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
D004268:DNA-Binding Proteins; C494041:ETS1 protein, human; D050981:Erythroid-Specific DNA-Binding Factors; C078433:FLI1 protein, human; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; D005819:Genetic Markers; C056564:ITGA2B protein, human; D039421:Integrin alpha2; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D019038:Platelet Glycoprotein GPIb-IX Complex; D050784:Proto-Oncogene Protein c-ets-1; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D018121:Receptors, Cytokine; D053628:Receptors, Thrombopoietin; D015534:Trans-Activators; D014157:Transcription Factors; C082218:MPL protein, human; D004247:DNA