Affiliation:
1. Laboratory of Experimental Hematology, Institute for Medical Research, Belgrade
2. Genetic Laboratory, Clinic of Endocrinology, Diabetes and Metabolic Diseases, Clinical Center of Serbia, Belgrade
Abstract
Introduction. Hydroxycarbamide, used in therapy of hemoglobinopathies,
enhances nitric oxide (NO) production both in primary human umbilical vein
endothelial cells (HUVECs) and human bone marrow endothelial cell line
(TrHBMEC). Moreover, NO increases ?-globin and fetal hemoglobin levels in
human erythroid progenitors. Objective. In order to find out whether simple
physiologic stimulation of NO production by components of hematopoietic
microenvironment can increase ?-globin gene expression, the effects of
NO-inducer bradykinin were examined in endothelial cells. Methods. The study
was performed in co-cultures of human erythroid progenitors, TrHBMEC and
HUVECs by ozone-based chemiluminescent determination of NO and real-time
quantitative RT-PCR. Results. In accordance with previous reports, the
endogenous factor bradykinin increased endothelial cell production of NO in a
dose- and time-dependent manner (0.1-0.6 ?M up to 30 minutes). This induction
of NO in HUVECs and TrHBMEC by bradykinin was blocked by competitive
inhibitors of NO synthase (NOS), demonstrating NOS-dependence. It has been
shown that bradykinin significantly reduced endothelial NOS (eNOS) mRNA level
and eNOS/?-actin ratio in HUVEC (by twofold). In addition, bradykinin failed
to increase ?-globin mRNA expression in erythroid progenitors only, as well
as in co-culture studies of erythroid progenitors with TrHBMEC and HUVEC
after 24 hours of treatment. Furthermore, bradykinin did not induce ?/?
globin ratio in erythroid progenitors in co-cultures with HUVEC. Conclusion.
Bradykinin mediated eNOS activation leads to short time and low NO production
in endothelial cells, insufficient to induce ?-globin gene expression. These
results emphasized the significance of elevated and extended NO production in
augmentation of ?-globin gene expression.
Funder
Ministry of Education, Science and Technological Development of the Republic of Serbia
Publisher
National Library of Serbia
Cited by
1 articles.
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