A 191-kb genomic fragment containing the human alpha-globin locus can rescue alpha-thalassemic mice

• Published in: Mammalian genome 2005-11, Vol.16 (11), p.847-853
• Main Authors: Al-Hasani, Keith, Vadolas, Jim, Knaupp, Anja S, Wardan, Hady, Voullaire, Lucille, Williamson, Robert, Ioannou, Panayiotis A
• Format: Article
• Language: English
• Subjects: alpha-Thalassemia - genetics; Animals; Chromatography, High Pressure Liquid; Chromosomes, Artificial, Bacterial - genetics; Chromosomes, Mammalian - genetics; Crosses, Genetic; Disease Models, Animal; Globins - deficiency; Globins - genetics; Humans; In Situ Hybridization, Fluorescence; Mice; Mice, Knockout; Mice, Transgenic; Transgenes - genetics
• ISSN: 0938-8990; 1432-1777
• DOI: 10.1007/s00335-005-0089-9

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.