An in vivo model for analysis of developmental erythropoiesis and globin gene regulation.
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.
2Cell and Gene Therapy Group, Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Parkville, VIC, 3052, Australia. jim.vadolas@mcri.edu.au.
Bradley
B
McColl
Betty R
BR
Kao
Preeyachan
P
Lourthai
Kasey
K
Chan
Hady
H
Wardan
Mark
M
Roosjen
Orane
O
Delagneau
Linden J
LJ
Gearing
Marnie E
ME
Blewitt
Saovaros
S
Svasti
Suthat
S
Fucharoen
Jim
J
Vadolas
D000818:Animals; D015254:DNA Modification Methylases / Q000378:metabolism; D004195:Disease Models, Animal; D044127:Epigenesis, Genetic; D041905:Erythroid Cells / Q000378:metabolism; D004920:Erythropoiesis / Q000502:physiology*; D005260:Female; D005319:Fetal Hemoglobin / Q000378:metabolism; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D013997:Time Factors; D019076:Transgenes; D055544:beta-Globins / Q000378:metabolism; D055545:gamma-Globins / Q000378:metabolism*
D055544:beta-Globins; D055545:gamma-Globins; D049452:Green Fluorescent Proteins; D005319:Fetal Hemoglobin; D015254:DNA Modification Methylases
BAC transgenics; chromatin modification; epigenetics; hemoglobin switching