title: Multiple physical stresses induce γ-globin gene expression and fetal hemoglobin production in erythroid cells.
abstract: Increased fetal hemoglobin (HbF) expression is beneficial for β-hemoglobinopathy patients; however, current inducing agents do not possess the ideal combination of efficacy, safety and ease of use. Better understanding the mechanisms involved in γ-globin gene induction is critical for designing improved therapies, as no complete mechanism for any inducing agent has been identified. Given the cytotoxic nature of most known inducing drugs, we hypothesized that γ-globin is a cell stress response gene, and that induction occurs via activation of cell stress signaling pathways. We tested this hypothesis by investigating the ability of physical stresses including heat-shock (HS), UV- and X-irradiation and osmotic shock to increase γ-globin gene expression in erythroid cells. Experiments in K562 and KU812 cells showed that each of these stresses increased steady-state γ-globin mRNA levels, but only after 3-5days of treatments. HS and UV also increased γ-globin mRNA and HbF levels in differentiating primary human erythroid cells. Mechanistic studies showed that HS affects γ-globin mRNA at multiple levels, including nascent transcription and transcript stability, and that induction is dependent on neither the master regulator of the canonical HS response, HSF1, nor p38 MAPK. Inhibitor panel testing identified PI3K inhibitor LY294002 as a novel inducing agent and revealed potential roles for NFκB and VEGFR/PDGFR/Raf kinases in HS-mediated γ-globin gene induction. These findings suggest that cell stress signaling pathways play an important role in γ-globin gene induction and may provide novel targets for the pharmacologic induction of fetal hemoglobin.
authors: Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Department of Pharmacology and Toxicology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Program in Experimental and Molecular Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.
authors: Emily K
authors: EK
authors: Schaeffer
authors: Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Department of Pharmacology and Toxicology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Program in Experimental and Molecular Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.
authors: Rachel J
authors: RJ
authors: West
authors: Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Department of Pharmacology and Toxicology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Program in Experimental and Molecular Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.
authors: Sarah J
authors: SJ
authors: Conine
authors: Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Department of Pharmacology and Toxicology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Program in Experimental and Molecular Medicine, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA. Electronic address: Christopher.H.Lowrey@dartmouth.edu.
authors: Christopher H
authors: CH
authors: Lowrey
mesh_terms: D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D041905:Erythroid Cells / Q000378:metabolism*; D004920:Erythropoiesis / Q000235:genetics; D005319:Fetal Hemoglobin / Q000096:biosynthesis* / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D000076249:Heat Shock Transcription Factors; D006453:Hemoglobinopathies / Q000235:genetics; D006358:Hot Temperature; D006801:Humans; D020014:K562 Cells; D009997:Osmotic Pressure; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014466:Ultraviolet Rays; D014965:X-Rays; D055545:gamma-Globins / Q000096:biosynthesis* / Q000235:genetics*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors; D047428:Protein Kinase Inhibitors; D014157:Transcription Factors; D055545:gamma-Globins; D005319:Fetal Hemoglobin; D048051:p38 Mitogen-Activated Protein Kinases
keywords: Erythropoiesis; Fetal hemoglobin; Sickle cell disease; Stress signaling