Stimulated stromal cells induce gamma-globin gene expression in erythroid cells via nitric oxide production.
OBJECTIVE
We have previously shown that nitric oxide (NO) is involved in the hydroxyurea-induced increase of gamma-globin gene expression in cultured human erythroid progenitor cells and that hydroxyurea increases NO production in endothelial cells via endothelial NO synthase (NOS). We have now expanded those studies to demonstrate that stimulation of gamma-globin gene expression is also mediated by NOS induction in stromal cells within the bone marrow microenvironment.


METHODS
Using NO analyzer, we measured NO production in endothelial and macrophage cell cultures. In coculture studies of erythroid and stromal cells, we measured globin gene expression during stimulation by NO inducers.


RESULTS
Hydroxyurea (30-100 microM) induced NOS-dependent production of NO in human macrophages (up to 1.2 microM). Coculture studies of human macrophages with erythroid progenitor cells also resulted in induction of gamma-globin mRNA expression (up to threefold) in the presence of hydroxyurea. NOS-dependent stimulation of NO by lipopolysaccharide (up to 0.6 microM) has been observed in human macrophages. We found that lipopolysaccharide and interferon-gamma together increased gamma-globin gene expression (up to twofold) in human macrophage/erythroid cell cocultures. Coculture of human bone marrow endothelial cells with erythroid progenitor cells also induced gamma-globin mRNA expression (2.4-fold) in the presence of hydroxyurea (40 microM).


CONCLUSIONS
These results demonstrate an arrangement by which NO and fetal hemoglobin inducers may stimulate globin genes in erythroid cells via the common paracrine effect of bone marrow stromal cells.
Cokić
Vladan P
VP
Laboratory of Experimental Hematology, Institute for Medical Research, University of Belgrade, 11129 Belgrade, Serbia. vl@imi.bg.ac.rs
Beleslin-Cokić
Bojana B
BB
Smith
Reginald D
RD
Economou
Antaeus P
AP
Wahl
Larry M
LM
Noguchi
Constance T
CT
Schechter
Alan N
AN
D000328:Adult; D000818:Animals; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D018920:Coculture Techniques; D004357:Drug Synergism; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D041905:Erythroid Cells / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D019899:Paracrine Communication / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D017154:Stromal Cells / Q000187:drug effects / Q000502:physiology*; D055545:gamma-Globins / Q000096:biosynthesis* / Q000235:genetics
D008070:Lipopolysaccharides; D012333:RNA, Messenger; D055545:gamma-Globins; D009569:Nitric Oxide; D007371:Interferon-gamma; D019331:NG-Nitroarginine Methyl Ester; D006918:Hydroxyurea