Localizing transcriptional regulatory elements at the mouse Dlk1 locus

Area of Science:

• Genomics
• Developmental Biology
• Gene Regulation

Background:

• Genomic imprinting controls allele-specific gene expression, but tissue-specific regulation is also critical.
• Proper expression of the imprinted Delta-like 1 (Dlk1)-Maternally expressed gene 3 (Meg3) gene pair is essential for mammalian fetal development.
• Mechanisms governing tissue-specific Dlk1 expression remain largely unknown.

Purpose of the Study:

• To identify cis-regulatory elements responsible for tissue-specific Dlk1 expression in the mouse embryo.
• To understand how these elements interact with imprinting mechanisms for precise gene control.

Main Methods:

• Utilized bacterial artificial chromosome (BAC) transgenes encompassing the Dlk1 gene and flanking regions.
• Performed in vivo and in vitro expression assays in mouse embryos.
• Employed cross-species sequence conservation analysis to pinpoint potential regulatory regions.
• Conducted luciferase and lacZ reporter assays to validate enhancer function.

Main Results:

• A large BAC transgene conferred expression in most endogenous Dlk1-expressing tissues.
• The majority of Dlk1 cis-regulatory elements were localized to a 41 kb region upstream of the gene.
• Cross-species conservation identified functional enhancer elements.
• Two specific elements drove lacZ reporter expression in Dlk1-expressing tissues.

Conclusions:

• The sequence upstream of Dlk1 contains at least two discrete regions regulating its tissue-specific expression.
• These findings contribute to understanding the complex regulation of imprinted genes.
• Elucidating these mechanisms is vital for understanding normal fetal development.