The perinatal switch from fetal to adult (gamma to beta) globin gene expression proceeds even in the presence of defective or absent adult beta globin genes, such as those producing sickle cell anemia and beta thalassemia. Preventing this developmental gene switch by maintaining expression of the fetal globin genes would prevent the clinical symptoms of the beta globin disorders from becoming manifest. This proposal is to confirm and extend our finding that administration of butyrate analogues, particularly during the switch period, can profoundly inhibit and reverse the globin gene switch and maintain fetal globin expression indefinitely. A long-term goal now is to develop a butyrate-based therapy for the beta globin disorders. We also propose to test the hypothesis, based on our preliminary data, that butyrate-like compounds increase and maintain gamma globin transcription by maintaining a chromatin structure that is accessible to positive regulatory elements and/or affecting binding of transcription factors in the gamma globin promoter region or distant upstream control region. We propose 1) to construct an effective, safe butyrate derivative with a long biologic half-life; 2) to further establish specificity of structure required for enhancing gamma globin expression without disrupting other developmental gene switches or affecting fetal growth; 3) to confirm that butyrate enhances gamma globin expression through an effect on the gamma globin promoter region and to investigate its effects on distant upstream control regions, and 4) to further define patterns of DNA binding proteins and nucleosomes in these regulatory regions in the presence of butyrate and 5) to determine any functional significance of these patterns using erythroid cells treated with butyrate analogues that are both effective and ineffective in stimulating gamma globin expression. This investigation may lead to a new therapy for the beta globin disorders and should provide further understanding of developmental globin gene switching.
