A composite transposon 3' to the cow fetal globin gene binds a sequence specific factor

Area of Science:

• Genomics
• Molecular Biology
• Comparative Genomics

Background:

• The beta-globin locus is crucial for oxygen transport and its regulation is complex.
• Repetitive DNA elements, such as Alu repeats, are abundant in mammalian genomes and can influence gene structure and function.
• Understanding the organization and evolution of gene loci provides insights into genomic regulation.

Purpose of the Study:

• To investigate novel sequence organizations within the bovine beta-globin locus.
• To characterize the structure and genomic distribution of identified repetitive elements.
• To explore the potential functional implications of these elements in gene regulation.

Main Methods:

• Southern blot analysis was employed to determine the copy number and genomic location of the identified sequences.
• Cloning and DNA sequencing were performed to analyze the precise structure of the lagan-Alu composite.
• Electrophoretic mobility shift assays (EMSA) were used to detect DNA-binding factors.

Main Results:

• Two unique composite sequences, termed lagan-Alu, were identified within the cow beta-globin locus.
• These composites, located near fetal and adult globin genes, were found to exist as two copies per haploid genome, with one copy outside the locus.
• Sequence analysis confirmed transposition of the lagan-Alu unit, and a lagan element near the fetal globin gene contained a binding site for a fetal-specific DNA-binding factor.

Conclusions:

• The bovine beta-globin locus harbors unusual composite repetitive elements (lagan-Alu) that have undergone transposition.
• The presence of a fetal-specific DNA-binding factor recognition site within a lagan element suggests a role in developmental gene regulation.
• These findings highlight the dynamic nature of mammalian genomes and the potential regulatory roles of interspersed repetitive elements.