A 191-kb genomic fragment containing the human alpha-globin locus can rescue alpha-thalassemic mice.
A 191-kb human bacterial artificial chromosome (BAC) containing the human alpha-globin genomic locus was used to generate transgenic mice that express, exclusively, human alpha-globin ((hu)alpha-globin). Expression of (hu)alpha-globin reaches a level of 36% of that of endogenous mouse alpha-globin ((mu)alpha-globin) on a heterozygous mouse alpha-thalassemia background ((mu)alpha-globin knockout, (mu)alpha(+/-)). Hemizygous transgenic mice carrying the (hu)alpha-globin locus on a heterozygous knockout background ((hu)alpha(+/0), (mu)alpha(++/--)) demonstrated complementation of most hematologic parameters. By crossing (hu)alpha(+/0), (mu)alpha(++/--) mice, we were able to generate mice entirely dependent on (hu)alpha-globin synthesis. Breeding and fluorescent in situ hybridization studies demonstrate that only mice homozygous for the transgene were able to rescue embryonic lethal homozygous (mu)alpha-globin knockout embryos ((mu)alpha(--/--)). Adult rescued mice produce hemoglobin at levels similar to wild-type mice, with partial red cell complementation based on mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and red cell distribution width (RDW) measurements. Significant erythrocythemia above wild-type levels seems to be the main compensatory mechanism for the normalization of the hemoglobin levels in the rescued animals. Our studies demonstrate that the (hu)alpha-globin locus in the 191-kb transgene contains all the necessary elements for the regulated expression of (hu)alpha-globin in transgenic mice. This animal model should be valuable for studying the mechanisms regulating (hu)alpha-globin production and for development of therapeutic strategies for beta-thalassemia based on downregulation of alpha-globin expression.
Al-Hasani
Keith
K
The CAGT Research Group, University of Melbourne Department of Paediatrics, The Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Melbourne, Victoria, Australia. Keith.Al-Hasani@med.monash.edu.au
Vadolas
Jim
J
Knaupp
Anja S
AS
Wardan
Hady
H
Voullaire
Lucille
L
Williamson
Robert
R
Ioannou
Panayiotis A
PA
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics*; D033481:Chromosomes, Mammalian / Q000235:genetics; D003433:Crosses, Genetic; D004195:Disease Models, Animal; D005914:Globins / Q000172:deficiency / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D019076:Transgenes / Q000235:genetics*; D017085:alpha-Thalassemia / Q000235:genetics*
D005914:Globins