An in vivo model for analysis of developmental erythropoiesis and globin gene regulation.

Abstract

Expression of fetal γ-globin in adulthood ameliorates symptoms of β-hemoglobinopathies by compensating for the mutant β-globin. Reactivation of the silenced γ-globin gene is therefore of substantial clinical interest. To study the regulation of γ-globin expression, we created the GG mice, which carry an intact 183-kb human β-globin locus modified to express enhanced green fluorescent protein (eGFP) from the Gγ-globin promoter. GG embryos express eGFP first in the yolk sac blood islands and then in the aorta-gonad mesonephros and the fetal liver, the sites of normal embryonic hematopoiesis. eGFP expression in erythroid cells peaks at E9.5 and then is rapidly silenced (>95%) and maintained at low levels into adulthood, demonstrating appropriate developmental regulation of the human β-globin locus. In vitro knockdown of the epigenetic regulator DNA methyltransferase-1 in GG primary erythroid cells increases the proportion of eGFP(+) cells in culture from 41.9 to 74.1%. Furthermore, eGFP fluorescence is induced >3-fold after treatment of erythroid precursors with epigenetic drugs known to induce γ-globin expression, demonstrating the suitability of the Gγ-globin eGFP reporter for evaluation of γ-globin inducers. The GG mouse model is therefore a valuable model system for genetic and pharmacologic studies of the regulation of the β-globin locus and for discovery of novel therapies for the β-hemoglobinopathies.

• Authors: Bradley McColl, Betty R Kao, Preeyachan Lourthai, Kasey Chan, Hady Wardan, Mark Roosjen, Orane Delagneau, Linden J Gearing, Marnie E Blewitt, Saovaros Svasti, Suthat Fucharoen, Jim Vadolas
• Journal: FASEB journal : official publication of the Federation of American Societies for Experimental Biology (FASEB J) Vol. 28 Issue 5 Pg. 2306-17 (May 2014) ISSN: 1530-6860 [Electronic] United States
• PMID: 24443374 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• beta-Globins
• gamma-Globins
• Green Fluorescent Proteins
• Fetal Hemoglobin
• DNA Modification Methylases

Topics

• Animals
• DNA Modification Methylases (metabolism)
• Disease Models, Animal
• Epigenesis, Genetic
• Erythroid Cells (metabolism)
• Erythropoiesis (physiology)
• Female
• Fetal Hemoglobin (metabolism)
• Gene Expression Regulation
• Green Fluorescent Proteins (metabolism)
• Male
• Mice
• Mice, Inbred C57BL
• Mice, Transgenic
• Mutation
• Promoter Regions, Genetic
• RNA Interference
• Time Factors
• Transgenes
• beta-Globins (metabolism)
• gamma-Globins (metabolism)