Hemoglobinopathies including sickle cell disease (SCD) and ?-thalassemia are the most common genetic disorders in the United States. SCD patients benefit from fetal hemoglobin (HbF;?2?2) induction to ameliorate clinical symptoms, decrease mortality and prolonged survival and quality of life. Treatment options for SCD are insufficient because therapeutic approaches to correct nitric oxide depletion and endothelium dysfunction attempted and failed at reversing the downstream negative effects of SCD. The FDA approved Hydroxyurea therapy was HbF inducing along with anti-inflammatory properties;unfortunately, Hydroxyurea is effective in only half of SCD patients. A critical barrier to progres in developing new and additional effective treatment options for SCD are gaps in knowledge and understanding of molecular mechanisms involved in ?-globin gene regulation. Our goal is to design novel molecular treatment strategies for SCD by beginning to address the gap in knowledge and understanding of molecular mechanisms involved in ?-globin gene regulation. Our central hypothesis is that alteration in stage-specific DNA-binding protein motifs mediated by heritable genetic mutations, produced chromatin modifications conducive to persistent HbF expression after birth. Our approach to the problem is built upon knowledge gleaned from naturally occurring mutations producing hereditary persistence of HbF (HPFH) expression phenotypes. Our objectives are to 1) determine the genomic interplay among known enhancers and a newly identified fetal chromatin domain and novel DNA- binding proteins in ?-globin regulation during human hemoglobin switching;and 2) discover plasma protein biomarkers and inherited genetic modifiers associated with HPFH in SCD. Our expected outcomes include: 1) development of molecular strategies for HbF induction for the treatment of SCD;2) generation of experimental data to fill knowledge gaps about ?-globin regulation;3) discovering novel plasma protein biomarkers and inherited genetic modifiers associated with HPFH in SCD that can act as an in vitro predictive surrogate of response to HbF inducing agents. Our impact on SCD medicine will include 1) creation of a new paradigm of molecular mechanisms involved in globin gene regulation during development;2) characterization of a novel fetal chromatin domain and its interaction with other known regulatory regions and 3) discovery of transcription factors that can be targeted for therapeutic intervention.
Aim 1 will test the hypothesis there exist a fetal chromatin domain involved in ?-globin regulation during erythropoiesis.
Aim 2 will test the hypothesis that plasma proteins associated with HPFH are expressed at different levels in SCD and that transcription factors mediating HPFH have altered expression to modulate HbF production.
Aim 3 will test the hypothesis that KLF1 activates negative transcriptional regulators of ?-globin expression during fetal erythropoiesis.
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