In patients with sickle cell disease (SCD), hydroxyurea (HU) ameliorates the symptoms by re-activating the fetal y-globin gene in adult erythroid cells. The molecular mechanism of HU in reactivating y-globin gene is not fully understood. In this application, we propose to test the hypothesis that a GATA switch mechanism underlies the mechanism of y-globin gene re-activation by HU: In adult erythroid progenitor cells of SCD patients, in which GATA-2 is non-detectable and GATA-1 is highly expressed, NF-Y binds to GATA-1 in forming a NFY/GATA-1 complex that represses y-globin gene. Treatment by HU drastically increases the level of GATA-2, so NF-Y through its higher affinity for GATA-2 then forms the NF-Y/GATA-2 complex that activates y-globin gene.
In Aim 1, we will determine by real-time RT-PCR and Western blots whether the level of y-globin gene re-activation is positively correlated with the level of GATA-2 inducible by HU in the erythroid progenitor cells of transgenic mice and SCD patients.
In Aim 2, we will use chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA) to determine whether the level of y-globin gene re-activation induced by HU is correlated with the level of GATA-2 bound to the y-globin promoter in the erythroid progenitor cells of transgenic mice and SCD patients.
In Aim 3, we will use transduction assays to determine whether over-expressing NF-Y and/or GATA-2 enhances y-globin gene re-activation in the erythroid progenitor cells of low HU-responders. It is anticipated that this project will provide insight into the molecular mechanisms involved in the transcriptional reactivation of the y-globin gene. At the translational level, this will lead to a refinement of HU usage in clinical therapeutics by identifying novel and early markers of response (increase in GATA-2) and thus differentiate responders from non-responders. The resultant targeted utilization of HU will not only address an important question of the mechanism of HU (as identified in the recent NIH HU consensus conference) but will also help alleviate a health disparity by allowing a more rational choice between HU and other anti-switching agents and avoiding unnecessary toxicities.
Understanding the activities of the NF-Y/GATA complexes assembled on the y-globin promoter may lead to development of a new generation of small chemical drugs that can specifically activate the y-globin gene without affecting other genes in adult erythroid cells of SCD patients. Such globin gene-specific drugs may avoid producing the wide-ranging, cytotoxic side effects of HU.
|Zhu, Xingguo; Hu, Tianxiang; Ho, Meng Hsuan et al. (2017) Hydroxyurea differentially modulates activator and repressors of ?-globin gene in erythroblasts of responsive and non-responsive patients with sickle cell disease in correlation with Index of Hydroxyurea Responsiveness. Haematologica 102:1995-2004|
|Piel, Frédéric B; Adamkiewicz, Thomas V; Amendah, Djesika et al. (2016) Observed and expected frequencies of structural hemoglobin variants in newborn screening surveys in Africa and the Middle East: deviations from Hardy-Weinberg equilibrium. Genet Med 18:265-74|
|Anea, Ciprian B; Lyon, Matthew; Lee, Itia A et al. (2016) Pulmonary platelet thrombi and vascular pathology in acute chest syndrome in patients with sickle cell disease. Am J Hematol 91:173-8|
|Ikuta, Tohru; Sellak, Hassan; Odo, Nadine et al. (2016) Nitric Oxide-cGMP Signaling Stimulates Erythropoiesis through Multiple Lineage-Specific Transcription Factors: Clinical Implications and a Novel Target for Erythropoiesis. PLoS One 11:e0144561|
|Baker, Charlotte; Grant, Althea M; George, Mary G et al. (2015) Contribution of Sickle Cell Disease to the Pediatric Stroke Burden Among Hospital Discharges of African-Americans-United States, 1997-2012. Pediatr Blood Cancer 62:2076-81|
|Jaja, Cheedy; Bowman, Latanya; Wells, Leigh et al. (2015) Preemptive Genotyping of CYP2C8 and CYP2C9 Allelic Variants Involved in NSAIDs Metabolism for Sickle Cell Disease Pain Management. Clin Transl Sci 8:272-80|
|Jaja, Cheedy; Patel, Niren; Scott, Stuart A et al. (2014) CYP2C9 allelic variants and frequencies in a pediatric sickle cell disease cohort: implications for NSAIDs pharmacotherapy. Clin Transl Sci 7:396-401|
|Gutsaeva, Diana R; Montero-Huerta, Pedro; Parkerson, James B et al. (2014) Molecular mechanisms underlying synergistic adhesion of sickle red blood cells by hypoxia and low nitric oxide bioavailability. Blood 123:1917-26|
|Ghoshal, Pushpankur; Rajendran, Mythilypriya; Odo, Nadine et al. (2014) Glycosylation inhibitors efficiently inhibit P-selectin-mediated cell adhesion to endothelial cells. PLoS One 9:e99363|
|Ikuta, Tohru; Kuroyanagi, Yuichi; Odo, Nadine et al. (2013) A common signaling pathway is activated in erythroid cells expressing high levels of fetal hemoglobin: a potential role for cAMP-elevating agents in ?-globin disorders. J Blood Med 4:149-59|
Showing the most recent 10 out of 19 publications