title: Characterization of transcription factor networks involved in umbilical cord blood CD34+ stem cells-derived erythropoiesis.
abstract: Fetal stem cells isolated from umbilical cord blood (UCB) possess a great capacity for proliferation and differentiation and serve as a valuable model system to study gene regulation. Expanded knowledge of the molecular control of hemoglobin synthesis will provide a basis for rational design of therapies for β-hemoglobinopathies. Transcriptome data are available for erythroid progenitors derived from adult stem cells, however studies to define molecular mechanisms controlling globin gene regulation during fetal erythropoiesis are limited. Here, we utilize UCB-CD34+ stem cells induced to undergo erythroid differentiation to characterize the transcriptome and transcription factor networks (TFNs) associated with the γ/β-globin switch during fetal erythropoiesis. UCB-CD34+ stem cells grown in the one-phase liquid culture system displayed a higher proliferative capacity than adult CD34+ stem cells. The γ/β-globin switch was observed after day 42 during fetal erythropoiesis in contrast to adult progenitors where the switch occurred around day 21. To gain insights into transcription factors involved in globin gene regulation, microarray analysis was performed on RNA isolated from UCB-CD34+ cell-derived erythroid progenitors harvested on day 21, 42, 49 and 56 using the HumanHT-12 Expression BeadChip. After data normalization, Gene Set Enrichment Analysis identified transcription factors (TFs) with significant changes in expression during the γ/β-globin switch. Forty-five TFs were silenced by day 56 (Profile-1) and 30 TFs were activated by day 56 (Profile-2). Both GSEA datasets were analyzed using the MIMI Cytoscape platform, which discovered TFNs centered on KLF4 and GATA2 (Profile-1) and KLF1 and GATA1 for Profile-2 genes. Subsequent shRNA studies in KU812 leukemia cells and human erythroid progenitors generated from UCB-CD34+ cells supported a negative role of MAFB in γ-globin regulation. The characteristics of erythroblasts derived from UCB-CD34+ stem cells including prolonged γ-globin expression combined with unique TFNs support novel mechanisms controlling the γ/β-globin switch during UCB-derived erythropoiesis.
authors.affiliation: Department of Pediatrics, Hematology/Oncology Division, Georgia Regents University, Augusta, Georgia, United States of America.
authors.forename: Biaoru
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology and Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.
authors.forename: Lianghao
authors.initials: L
authors.lastname: Ding
authors.affiliation: Department of Radiation Oncology and Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.
authors.forename: Chinrang
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Pediatrics, Hematology/Oncology Division, Georgia Regents University, Augusta, Georgia, United States of America.
authors.forename: Baolin
authors.initials: B
authors.lastname: Kang
authors.affiliation: Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, Texas, United States of America.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Radiation Oncology and Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Story
authors.affiliation: Department of Pediatrics, Hematology/Oncology Division, Georgia Regents University, Augusta, Georgia, United States of America.
authors.forename: Betty S
authors.initials: BS
authors.lastname: Pace
mesh_terms: D018952:Antigens, CD34 / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics*; D004900:Erythroblasts / Q000166:cytology / Q000378:metabolism; D015672:Erythroid Precursor Cells / Q000166:cytology; D004920:Erythropoiesis / Q000235:genetics; D005312:Fetal Blood / Q000166:cytology* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D000090062:Kruppel-Like Factor 4; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D055544:beta-Globins / Q000096:biosynthesis / Q000235:genetics; D055545:gamma-Globins / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D014157:Transcription Factors; D055544:beta-Globins; D055545:gamma-Globins