Hydroxyurea generates nitric oxide in human erythroid cells: mechanisms for gamma-globin gene activation.

Pubmed ID: 19657070

Pubmed Central ID: PMC3827858

Journal: Experimental biology and medicine (Maywood, N.J.)

Publication Date: Nov. 1, 2009

Affiliation: University of Texas at Dallas, Department of Molecular and Cell Biology, Richardson, Texas 75080, USA.

MeSH Terms: Humans, Fetal Hemoglobin, Signal Transduction, Stem Cells, Cyclic GMP, Erythroid Cells, Hydrogen Peroxide, Hydroxyurea, K562 Cells, Nitrates, Nitric Oxide, Nitric Oxide Synthase, Nitrites, Transcription, Genetic, Transcriptional Activation, gamma-Globins, omega-N-Methylarginine

Grants: HL69234, R01 HL069234

Authors: Lou TF, Singh M, Mackie A, Li W, Pace BS

Cite As: Lou TF, Singh M, Mackie A, Li W, Pace BS. Hydroxyurea generates nitric oxide in human erythroid cells: mechanisms for gamma-globin gene activation. Exp Biol Med (Maywood) 2009 Nov;234(11):1374-82. Epub 2009 Aug 5.

Studies:

Abstract

Hydroxyurea (HU) induces fetal hemoglobin synthesis through activation of cyclic guanine monophosphate (cGMP) signaling. Studies in sickle cell patients demonstrated increased circulating nitric oxide (NO) levels after oral HU treatment. However, the direct measurement of NO in erythroid cells and its role in fetal hemoglobin induction have not been defined. Therefore, we quantified the level of nitrate and nitrite (NOx) generated by HU in human erythroid progenitors in the presence of three nitric oxide synthase inhibitors (NOS), including N(G)-monomethyl-L-arginine (L-NMMA). In addition, cGMP levels were measured in the presence or absence of the pathway inhibitor 1H-(1,2,4)ox-adiazolo(4,3-a)quinoxalin-1-one, which blocks soluble guanylyl cyclase formation. HU treatment increased NOx levels and gamma-globin transcription in K562 and primary erythroid cells, which was augmented when HU was combined with L-NMMA. Pretreatment with the cGMP pathway inhibitor reversed gamma-gene activation by HU. These data demonstrate the direct stimulation of cellular NO and cGMP signaling in erythroid progenitors by HU as a possible mechanism for gamma-globin gene activation.