Globin gene expression in Hb Lepore-BAC transgenic mice

Area of Science:

• Genetics
• Molecular Biology
• Hematology

Background:

• The beta-globin gene cluster is crucial for hemoglobin production.
• Understanding gene regulation in this cluster is key for treating hemoglobinopathies like thalassemia.
• The Hb Lepore fusion gene offers a model to study complex globin gene interactions.

Purpose of the Study:

• To create and characterize transgenic mouse models for studying the Hb Lepore deltabeta fusion gene.
• To investigate the developmental regulation and expression levels of the human deltabeta transgene in mice.
• To assess the potential for fetal hemoglobin induction in these models.

Main Methods:

• Generation of five transgenic mouse lines using Bacterial Artificial Chromosomes containing the human beta-globin gene cluster.
• Analysis of transgene integration and copy number.
• Quantification of human globin chain expression during development.
• Evaluation of fetal hemoglobin (HbF) levels and response to pharmacologic induction.

Main Results:

• Transgenic mice successfully carried 1-3 copies of the Hb Lepore deltabeta fusion gene.
• Human globin genes exhibited normal developmental regulation, mirroring endogenous gene expression.
• Deltabeta transgene expression was detected in fetal life, reaching a mean of 13.0% in adults, comparable to human levels.
• Low levels of human gamma chains (F cells) were observed in adult mice, but did not increase with pharmacologic induction, even in a thalassemic background.

Conclusions:

• Transgenic mice with the Hb Lepore deltabeta fusion gene accurately model human beta-globin gene regulation.
• The deltabeta transgene achieves physiologically relevant expression levels in adult mice.
• These models demonstrate a lack of pharmacologic fetal hemoglobin induction, suggesting limitations in their utility for studying certain therapeutic strategies.